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Issue 1, Volume 7,
January 2008
Title
of the Paper: A Simple Adaptive p-persistent MAC Scheme for Service
Differentiation and Maximum Channel Utilization
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Authors:
Bai Xiang, Mao Yu-Ming
Abstract: In this paper, we propose an adaptive p-persistent MAC scheme,
named QDA-MAC (QoS differentiation based adaptive MAC scheme), for WLAN to
maximize the channel utilization and provide the service differentiation
among different traffic stations. Specifically, different from the previous
works, the proposed scheme does not need to estimate the number of active
stations for each priority class and still achieves the channel utilization
close to its optimal value by exploiting a new parameter, persistent factor,
whose optimal value can dynamically follow the change of the load based on a
simple estimation of the network status. At the same time, the transmission
probability of each priority class can be updated by optimal persistent
factor. Simulation and numerical results show that QDA-MAC can achieve much
higher channel utilization and shorter delay than standard IEEE 802.11 DCF
and IEEE 802.11e EDCA in all different WLAN environments.
Keywords: QoS differentiation; p-persistent; persistent factor;
adaptive scheme; transmission attempt
Title
of the Paper: New Algorithm for Power Control in Cellular Communication
with ANFIS
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Authors:
Shahab Asoodeh
Abstract: Transmitter power is an important resource in cellular mobile radio
systems. Effective power control can increase system capacity and quality of
service. A commonly used measure of the quality of service is the Carrier to
Interference Ratio (CIR) at the receiver. The main idea on power control
schemes is to maximize the minimum CIR in each channel of system. In this
paper a new adaptive neuro fuzzy distributed power control algorithm which
can be used to maximize the minimum CIR among all of co-channel users, has
been introduced. Simulations and results have been compared with classical
method and show that intelligent control system has better performance than
other existing methods.
Keywords: Cellular mobile communication, Power control, ANFIS, MF
Title
of the Paper: Design of Optimal Space-Time Codes in TDD/TDMA 4G
Systems
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Authors:
Zhaogan Lu, Jincang Han, Paul Fahamuel, Taiyi Zhang
Abstract: Under the scenarios of fast mobile frequency selective channels, it
is a very intractable issue to design the optimal space time codes (ST) that
can achieve the optimal diversity and multiplexing gains tradeoff with
full-diversity full-rate (FDFR) constrains. Therefore, an optimal space time
design scheme is given in this paper for one novel 4G cellular communication
systems with time division duplex (TDD) and time divisions multiple access
(TDMA). The system is designed to overcome the great channel estimation
overhead and the complexity of multiple user detectors in the cases of
multiple antennas at transceivers. Here, one FDFR code given in recent
literatures is adopted for the proposed TDD/TDMA 4G systems, which was proved
in this paper to achieve the optimal diversity-multiplexing gain tradeoff. In
typical cellular channel profiles, several space time schemes with optimal or
sub-optimal tradeoff are tested with TDD/TDMA 4G systems with 8x2 antenna
configurations at base and mobile stations respectively. Numerical results
show that the FDFR design could achieve the maximal system throughout with
better adaptive capacity to wireless link states than that of space time
block codes (STBC) and Diagonal Bell Laboratories Layered Spare-Time Codes
(D-BLAST). Furthermore, the performance of the proposed FDFR design for
TDD/TDMA 4G systems could achieve better tradeoff for throughput and system
symbol error rates than that of the cyclic-division-algebra (CDA) space time
codes.
Keywords: MIMO, diversity and multiplexing tradeoff, 4G, space time
codes, full-diversity and full-rate
Issue 2, Volume 7,
February 2008
Title
of the Paper: Energy Balancing by Combinatorial Optimization for
Wireless Sensor Networks
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Authors:
J. Levendovszky, A. Bojarszky, B. Karlocai, A. Olah
Abstract: In this paper novel protocols are developed for wireless sensor networks
(WSNs) in order to ensure reliable packet transmission and maximize lifespan
at the same time. The optimal transmission energies are derived which
guarantee that the packets are received by the Base Station (BS) with a given
reliability subject to achieving the longest possible lifespan. These
protocols can be applied in biomedical applications where energy consumption
and longevity is of crucial importance. The optimization has been carried out
for the chain protocol (when nodes are forwarding the packets toward the BS
via the neighbouring nodes) and for the shortcut type of protocols (when a
packet may get to the BS by being first transferred in the chain up to a
certain node which then sends it directly to the BS). The new results have
been tested by extensive simulations which also demonstrated that the
lifespan of WSN can significantly be increased by the new protocols.
Keywords: Communication systems, Communication system routing, Network
reliability, Protocols.
Title
of the Paper: Push-Pull Incentive-based P2P Live Media Streaming System
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Authors:
Poo Kuan Hoong, Hiroshi Matsuo
Abstract: Peer-to-peer (P2P) file sharing has become increasingly popular,
accounting for as much as 70% of Internet traffic by some estimates. Recently,
we have been witnessing the emergence of a new class of popular P2P
applications, namely, P2P audio and video streaming. While traditional P2P
file distribution applications target elastic data transfers, P2P streaming
focuses on the efficient delivery of audio and video content under tight
timing requirements. In these applications, each node independently selects
some other nodes as its neighbors and exchanges streaming data with
neighbors. In this paper, we propose and investigate a full distributed,
scalable, and cooperative protocol for live video streaming in an overlay
peer-to-peer network. Our protocol, termed P2P Unstructured Live Media
Streaming (PALMS), makes use of combination of push-pull score-based
incentive method to achieve high performance (in term of delay, stream
continuity, cooperation, etc.). The main contribution of PALMS is that it
reduces the end-to-end streaming delay and in turn results better delivered
quality. Furthermore, with the implementation of score-based incentive
mechanism, PALMS is resilient to existence of free-riders and encourage
cooperation among participating nodes. We have extensively evaluated the
performance of PALMS. Our experiments demonstrate that PALMS achieves good
streaming quality even under the existence of free-riders.
Keywords: peer-to-peer, streaming, free-riders, overlay, push-pull
Title
of the Paper: Diversity Techniques to
Combat
Fading in WiMAX
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Authors:
Anou Abderrahmane, Mehdi Merouane, Bensebti Messaoud
Abstract: The IEEE 802.16 standard is often referred to as WiMAX today. It
represents a distillation of the most advanced technology and an industry
consensus permitting equipment interoperability. It holds the promise of
delivering high speed internet access to business and residential customers
and to remote locations where traditional broadband services are unavailable.
In the present work, the PHY specified for the Wireless MAN-OFDM case is
studied and implemented. Various modulation techniques involved are explored
and each of the performances enhancing techniques is evaluated with regard to
its functionality in the system. The simulation results show that the
Space-Frequency Coded system coupled with Reed-Solomon codes and
Convolutional codes efficiently exploits diversity techniques.
Keywords: WiMAX, BWA, OFDM, MIMO, STBC, Convolutional Codes,
Reed-Solomon codes
Title
of the Paper: Information-Theoretic Comparison of Channel Capacity for
FDMA and DS-CDMA in a Rayleigh Fading Environment
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Authors:
Panagiotis Varzakas
Abstract: In this paper, a comparative estimate of the channel capacity
assigned to each user for frequency-division multiple-access (FDMA) and
direct-sequence code-division multiple-access (DS-CDMA) schemes operating in
a Rayleigh fading channel is presented. Then, the achievable channel capacity
per user (in the Shannon sense) is estimated in an average sense considering
the inherent diversity potential that both schemes provide in a Rayleigh
fading channel. The non-equal user rate for the DS-CDMA case is studied,
considering the ratio of two neighboring user channel capacities. Hence, it
is shown that, in contrast to the equal user rate, for non-equal user rate
case in DS-CDMA and under normalized conditions, the average channel capacity
per user, in FDMA, is higher than that of DS-CDMA and this result is
quantitatively evaluated in terms of a defined average capacity gain factor.
Keywords: Channel capacity, code-division multiple-access,
frequency-division multiple-access, Rayleigh fading.
Title
of the Paper: A New Group Mobility Model for Mobile Adhoc Network based on
Unified Relationship Matrix
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Authors:
S.
Gunasekaran, N.
Nagarajan
Abstract: is meaningful when they use realistic movement mobility models,
which directly impacts the performance of the protocols. Once the nodes have
been initially distributed, the mobility model dictates the movement of the
nodes within the network. If this movement is unrealistic, the simulation
results obtained may not correctly reflect the true performance of the
protocols. The majority of existing mobility models for adhoc networks do not
provide realistic movement. Mobility model based on social network theory
predicts the node movements more realistic. Our paper reinforces the model by
using Unified Relationship Matrix, which improves the movements of groups. Unified
Relationship Matrix helps to represent the relationships of inter and intra
type of nodes. Movements of nodes and groups are evaluated by keeping a small
distance between each node and maintaining each group velocity, direction and
movements. Group velocity is calculated by inter relationship matrix and
cumulative nodes velocity. Group movements are calculated and directed by
Unified Relationship Matrix.
Keywords: Adhoc networks, Mobility, Social Networks, Unified
Relationship Matrix, Mobile Nodes, Mobile Groups
Title
of the Paper: Performance Improvement of Clustered Mobile Ad hoc Networks
using a CDMA Single Channel and Based on Admission Control Approach
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Authors:
Zouhair El-Bazzal, Michel Kadoch, Basile Agba, Francois Gagnon
Abstract: Clustering has been proven to be a promising approach for mimicking
the operation of the fixed infrastructure and managing the resources in
multi-hop networks. In this paper, we propose an Efficient Clustering
Algorithm (ECA) in Mobile Ad hoc Networks based on the quality of service’s
(QoS) parameters (cluster throughput/delay, packet loss rate). The goals are
yielding low number of clusters, maintaining stable clusters, and minimizing
the number of invocations for the algorithm. The performance changes greatly
for small and large clusters and depends strongly on the formation and
maintenance procedures of clusters which should operate with minimum
overhead, allowing mobile nodes to join and leave without perturbing the
membership of the cluster and preserving current cluster structure as much as
possible. In this manner, while QoS does not perform well under high traffic
load conditions, admission control becomes necessary in order to provide and
support the QoS of existing members. Based on the results from the proposed
analytical model, we implement a new admission control algorithm that
provides the desired throughput and access delay performance in order to
determine the number of members inside an ECA cluster that can be
accommodated while satisfying the constraints imposed by the current
applications. Through numerical analysis and simulations, we have studied the
performance of our model and compared it with that of WCA. The results demonstrate
the superior performance of the proposed model.
Keywords: Clustering, Weight, Election, Throughput, Delay
Title
of the Paper: Channel Coding as a Cryptography Enhancer
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Authors:
Natasa Zivic, Christoph Ruland
Abstract: In this work, channel decoding is considered as a promising way for
improvement of cryptographic functions. Use of MAC/H-MAC values and digital
signatures is analyzed in a context of code concatenation, together with
convolutional codes using MAP decoding algorithm. Soft Input Decryption
method, which uses L-values from channel decoder, presents an efficient
method for integrating cryptography into decoding. The results of computer
simulations that implement this method have been also presented. Additionally,
the number of L-values verifications has been tested and compared with the
theoretical results.
Keywords: Soft Input Decryption, Code Concatenation, L-values,
MAC/H-MAC, MAP, Channel Decoding, Turbo Decoding, CCER
Title
of the Paper: Challenge of Channel Estimations and Its Way Out in MIMO
OFDM Systems for Mobile Wireless Channels
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Authors:
Zhaogan Lu, Taiyi Zhang, Zhengwei Gong, Liejun Wang
Abstract: In current common channel estimation schemes for MIMO OFDM systems,
channel state information is usually achieved by estimating channels
according to frequency domain pilot sequences. However, when the length of
MIMO OFDM symbols is larger than that of wireless channel delay, there are
two intractable issues in the case of cellular fast fading channel scenarios
with large numbers of users, i.e., the bandwidth overhead of channel
estimation and the difficulty to construct large numbers of orthogonal
training sequences. Inspired from the Steiner channel estimation method in
multi-user CDMA uplink wireless channels, we proposed a new design scheme of
training sequence in time domain to conduct channel estimation in MIMO OFDM
systems. According to the proposed schemes, training sequences of different
transmit antennas can be simply obtained by truncating the circular extension
of one basic training sequence, and the pilot matrix assembled by these
training sequences is one circular matrix with good reversibility. Furthermore,
when the length of channel profiles is less than that of MIMO OFDM symbols,
more bandwidth resources can be saved, as the training sequence only occupies
a part of MIMO OFDM symbols. At last, we analyze the classical common time
and frequency domain schemes in terms of channel overheads and computation
complexity, and the results disclose the proposed scheme can be one way out
for current common frequency domain channel estimation issues. For typical
ITU indoor, pedestrian and vehicular channel profiles, the corresponding
numerical results indicate the proposed method can save abundant bandwidth
and achieve good channel estimation accuracy when compared with classical
frequency and time domain approaches, respectively.
Keywords: channel estimation, wireless communications, MIMO, OFDM,
pilot sequences
Title
of the Paper: Yaw Phase Mode Attitude Control Using Z Wheel for LEO
Microsatellite
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Authors:
A.
M. SI Mohammed, M. Benyettou, A. Boudjemai Y. Hashida, M.
N. Sweeting
Abstract: A control system is proposed for a low Earth orbit gravity gradient
stabilised microsatellite using Z wheel. The microsatellite is 3-axis
stabilized using a yaw reaction wheel, with dual redundant 3-axis
magnetorquers. Two vector magnetometers and four dual sun sensors are carried
in order to determine the full attitude. The attitude was estimated using an
Euler angles (small libration version) on based extended Kalman filter (EKF).
After the satellite has been detumbled and deploy the gravity gradient boom,
in order to have the accurate Nadir pointing we will use the Z zero-bias mode
controller. The Z momentum wheel will be damped by the magnetorquers. This
paper describes the attitude determination and control system design of LEO
microsatellite using Z reaction wheel for yaw phase mode control.
Keywords: Modelling, Simulation, Microsatellite, LEO, Attitude, Yaw,
Control, Z Wheel, Magnetorquer.
Title
of the Paper: Two-Valued Integrand Coding Transmission of Multi-Rate
Quasi-Synchronous CDMA Signals Convolved by Real-Valued Self-Orthogonal
Finite-Length Sequences
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Authors:
Jiong Le, Yoshihiro Tanada
Abstract: The next generation mobile communication system is desired to
transmit multimedia information at multi-rate. Two-valued integrand codes are
applied to the realization of the multi-rate quasi-synchronous CDMA system
using real-valued self-orthogonal finite-length sequences with zero correlation
zone. Each user data of multi-level and multi-interval and a common
synchronizing sequence are convolved with the user sequence and converted to
two-valued integrand coding signal. The signal passes through low pass
filters in a transmitter and a receiver and is changed to a real-valued
signal. In the receiver, the desired data are detected by the correlation
processing with the respective code. This transmission system suppresses
distortion on amplitude limitation and quantization, and interchannel and
intersymbol interferences. Two-valued integrand coding contributes to easy
amplification and modulation.
Keywords: multi-rate transmission, two-valued integrand code,
self-orthogonal finite-length sequence, zero correlation zone, convolution,
amplitude distortion, quasi-synchronous CDMA.
Title
of the Paper: Identification of Communication Solution designated for
Transport Telematic Applications
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Authors:
Tomas Zelinka, Miroslav Svitek
Abstract: Communications solution represents one of the key parts of the
Intelligent Transport system (ITS). Goal of our research is to improve
over-ground traffic efficiency and security, specifically on the airport
territory, where pilot installation was set-up and tested with aim to confirm
its ability to improve conditions for efficient management of the over-ground
traffic of all moving object in area including moving aircrafts and all types
of service vehicles. ITS system requirements on the communications
environment are usually quantified indirectly by telematic sub-system
performance indicators. Correct selection and configuration of the
appropriate communication solution are achievable, if "transformation
matrix" between vectors of communications and telematic performance
indicators is correctly identified. Principles of developed method based on
such transformation matrix identification are introduced. Application of the
proposed methodology is demonstrated on the CaMNA communications system
identification and its parameters settings. Airport territory has got quite
complex arrangement and there are very different requirements on telematic
system performance in different parts of the airport area. This fact leads to
application core wireless access service securely combined with set of the
alternative technologies applied in areas, where the core service is not
available for technical or economical reason. Management of such system is
based on implementation of the CALM family of standards or its mutations with
implemented effective and safe decision processes. Correctly designed
decision processes supporting selection of the “best possible” alternative
represent one of key issues of the whole solution. Results of the
communication solution parameters tests processed within limited pilot
installation and relevant recommendations are presented as the last part of
this paper.
Keywords: Intelligent Transport Systems, Telecommunications
Performance Indicators, Telematic Performance Indicators, Global Navigation
Satellite System, handover, Quality of Service
Title
of the Paper: Middleware Design of Bandwidth Constrained QoS Model for
Multi Hop Ad Hoc Networks
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Authors:
M.
Sulleman Memon, Niaz A.
Memon,
Manzoor Hashmani
Abstract: Middleware is actually a resource manager that guarantees the implementation
of all policies, contracts to be satisfied, and it ensures that contracts do
not go beyond the limits of network capacity. It also authentication, so that
only the legitimate users could avail the network resources according to the
agreed format. The middleware is supposed to be the backbone for QoS
assurance and the system behavior depends on it. This paper proposes design
of a middleware based on a bandwidth constrained QoS model for multi hop ad
hoc networks. Our model is designed not only on the basis of
conceptualization but we have considered the basic functionalities available
in networking equipments like routers etc. The elements of QoS aware
middleware are admission control, resource reservation, policy control and a
feedback module. Finally we discuss our future work to find the primary and
alternative route to the destinations by keeping the bandwidth constraints in
mind.
Keywords: Multi hop, Ad hoc Networks, Packet Classifier, Resource
Reservation, Quality of Service, Real Time Applications
Issue 3, Volume 7,
March 2008
Title
of the Paper: Performance Evaluation of IEEE 802.1x Authentication Methods
and Recommended Usage
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Authors:
Monis Akhlaq, Baber Aslam, Muzammil A Khan, John Mellor, M Noman Jafri,
Irfan Awan
Abstract: The wide spread acceptance of IEEE WLANs is a result of industrial
standardization to ensure product compatibility and reliability among various
manufacturers. Several WLANs solutions are available with varying
characteristics and interoperability. The IEEE Standard 802.11 is one of the
most widely adopted mechanisms for wireless LANs. It defines both physical
(PHY) and medium access control (MAC) layer protocol however; it provides
limited data confidentiality and has cumbersome procedure for key exchange. In
response IEEE introduced a port based network access control standard 802.1x
to authenticate and authorize devices interconnected various IEEE 802 LANs.
802.1x only defines authentication not the actual authentication method which
allows the developers to construct their own algorithm and consequently a lot
of wireless vendors implemented their own 802.1x adaptation such as MD5
Message Digest 5 , TLS (Transport Layer Security) , TTLS (Tunneled TLS) ,
PEAP (Protected Extensible Authentication Protocol), LEAP (Lightweight
Extensible Authentication Protocol) and others. This versatility in 802.1x
adaptations has made it difficult for the WLANs users to choose an
appropriate mechanism in relation to performance and security of networks. An
effort has been made in [1] to carry out comparative analysis of IEEE
authentication methods in different security combinations. This work
supplements the efforts cited in [1] and incorporates more results in added
network configurations. The paper finally recommends the users an appropriate
IEEE authentication methods depending upon the need, requirements and
security concerns.
Keywords: Authentication, Packet, Round Trip Time, Security,
Throughput, Wireless LANs, 802.1x.
Title
of the Paper: Requirements for a New Resource Reservation Model in Hybrid
Access Wireless Network
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Authors:
Tudor Palade, Emanuel Puschita
Abstract: The wireless systems entered a phase characterized by the
integration of the existing platforms into hybrid access wireless IP
architectures. The requests of the real time applications ran in heterogeneous
environments need the presence of a mechanism for resource negotiation and
management. The paper suggests the design and implementation of an
inter-domain QoS mechanism in a hybrid access wireless IP architecture using
mobile agents. The hybrid access wireless IP architecture intends to
integrate wireless spatial and terrestrial wide area networks, and wireless
metropolitan and local area networks. The demands imposed to the inter-domain
QoS mechanism recommend the use of mobile agents as an alternative to the
classical method of resource reservation and QoS parameters transfer. In
order to provide the quality of services, mobile agents act on behalf of the
user. Inter-domain QoS support proposed by this mechanism needs the
accomplishment of three phases: resource negotiation, resource allocation,
and resource management. Each phase is associated to a corresponding specific
profile. The purpose of the mobile agents is to determine the selection of a
corresponding profile according to the negotiated set of QoS parameters.
Keywords: Resource Reservation, QoS Mechanisms, Hybrid Wireless Access
Title
of the Paper:
The System Transfering between Laser-Satellites
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Authors:
Marketa Smejkalova Mazalkova
Abstract: Laser inter-satellite communication is on the verge of becoming a
reality. It will be a key building block for wide-area space data networks of
the future. Design methodologies treating these as complex engineering
systems, and the technique to break down the systems into interacting but
logically separate subsystems for design and analysis, will be suggested. The
paper involves the introduction into laser inter-satellite communication
system. The paper includes briefly analysis, optimization and subsystems
design (three independent links) and system level development of signal
transferring between two GEO satellites. Research opportunities in this area
include development of laser beam acquisition, tracking and pointing
techniques and algorithms, development of computer aided analysis link budget
for the free space channel, systems engineering (analysis and design) of
optical transmission development of high efficiency flight qualifiable
solid-state lasers, fast fine-pointing mirrors high update-rate acquisition
and tracking cameras and very low-noise high-quantum efficiency receiver.
Keywords: Acquisition, tracking, data transfer, laser, satellite
systems, laser communication, space channel
Title of
the Paper: Network Architectures Exploiting Multiple HAP Constellations
for Load Balancing
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Authors:
Tine Celcer, Ales Svigelj, Mihael Mohorcic
Abstract: This paper addresses network architectures in a constellation of
high altitude platforms (HAPs) with overlapping coverage areas, focusing on
the additional network elements/functionalities required to make use of load
balancing mechanisms. According to the location within the network and the
complexity of additional equipment/ functionality the paper proposes two
different architectures. In the case of the basic utilisation of multiple
HAPs a new equipment/functionality is installed only at the user premises,
supporting load balancing only for the connections initialised from the HAP
user network to the Internet (i.e. the outbound connections). In the case of
advanced utilisation of multiple HAPs a new equipment/functionality is needed
both at the user premises and in the HAP network, thus supporting load
balancing in both directions. For the performance evaluation of load
balancing mechanisms we built a simulation model supporting typical
applications such as e-mail, file transfer, web browsing and IP telephony. Simulation
results confirm that in the case of traffic load close to the congestion load
balancing mechanism significantly improves the performance of selected
reference applications. In order to asses the feasibility of the proposed
network architectures in a multiple HAP system, and to confirm that carefully
designed and pointed directional user antennas allow establishment of
multiple access links for load balancing and to improve resilience of the
network, we also investigate HAP visibility distribution across the coverage
area for a single HAP system and a system comprising 4 HAPs.
Keywords: High Altitude Platforms, network architectures, load
balancing, multiple HAP constellation
Title
of the Paper: Using Randomized Association ID to Detect and Prevent
Spoofed PS-Poll Based Denial of Service Attacks in IEEE 802.11 WLANs
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Authors:
Zaffar I. Qureshi, Baber Aslam, Athar Mohsin, Yonus Javed
Abstract: Wireless Local Area Networks (WLAN) provide connectivity along with
flexibility at low cost. Appreciating the exponential growth in this area,
the Institute of Electrical and Electronics Engineers (IEEE) ratified IEEE
standard 802.11
in 1999 which was widely accepted as
the defacto industry standard for interconnection of portable devices. Due to
the scarcity of battery power in portable devices operating in WLANs, IEEE
802.11 directly addressed the issue of Power Saving (PS) and defined a whole
mechanism to allow stations (STA) to go into sleep mode without losing
information, as Access Point (AP) keeps buffering the messages directed to
the sleeping STA. Growing use of IEEE 802.11 lead to the identification of
flaws in security specifications of the standard known as Wired Equivalent
Privacy (WEP). These flaws were addressed by the introduction of
amendments/enhancements. However, IEEE‟s
security enhancements failed to achieve desired objectives especially
availability, which is the main concern of any network administrator. Identity
theft due to unauthenticated management and control frames left a window open
for hackers to launch successful Denial of Service (DoS) attacks. The PS
functions of 802.11 present several identity based vulnerabilities,
exploiting which, an attacker can spoof a polling message on behalf of STA
and cause AP to discard buffered packets of the client while it is asleep. As
a result, an attacker can block victim STA from receiving frames from AP,
thus launching a successful DoS attack. The mechanism proposed in [1]
addresses the issue of spoofed PS-Poll based DoS attack and proposes a robust
solution to this problem. Although the proposed solution was a novel idea;
however it was only a mathematical analysis, not verified or tested by
implementation on hardware or through simulation. In this extended version of
the paper, an endeavor has been made to implement the theoretical idea and
validate the mathematical calculations through simulation.
Keywords: Wireless security, Denial of service DoS, 802.11, Power
Saving PS, PS-Poll, Association ID
Title
of the Paper: Design of Broad-Beam Microstrip Reflectarray
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Authors:
Piyaporn Krachodnok, Rangsan Wongsan
Abstract: The reflectarray’s elements arrangement for generating an arbitrary
phase distribution in the antenna aperture and thus a wide beamwidth of the
far field pattern is presented. The desired phase delay of reflectarray
elements, which duplicated the same radiating aperture as backscatters, is
determined on the construction of the curvature of a shaped backscatter
surface with the help of Snell's law for beam forming to cover a broad area. The
Method of Moments (MoM) and the infinite-array are applied to calculate
reflection phase characteristics. The phase and radiation pattern synthesis
method for microstrip reflectarray that has to illuminate a predefined
circular area are presented by using a variety of discretization of
elementary geometrical functions such as, triangular, quadratic, circular,
gaussian, cosine, squared cosine, and parabolic distributions. These
backscatter functions are discussed in terms of merits and demerits to find
appropriate radiation characteristics such as radiation pattern, -3 dB
beamwidth, and maximum gain for utilization in Wireless Local Area Network
(WLAN) application. The optimized feed distance is calculated from the
aperture efficiency by considering feed blockage efficiency and the influence
of the feed position on the -3 dB beamwidth and gain performance has been
investigated. Having confirmed the validity of this approach, the X-band
antenna prototype is designed and developed. This reflectarray is tested
experimentally and shows good performance.
Keywords: reflectarray, phase array, broad-beam antenna
Title
of the Paper: Binomial and Monotonic Behavior of the Probability of
Undetected Error and the 2-r-Bound
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Authors:
Wacker H. D., Boercsoek J.
Abstract: Proper linear codes play an important role in error detection. They
are characterized by an increasing probability of undetected error pue(ε,C) and
are considered “good for error detection”. A lot of CRCs commonly used to
protect data transmission via a variety of field busses are known for being
proper. In this paper the weight distribution of proper linear codes on a
binary symmetric channel without memory is investigated. A proof is given
that its components are upper bounded by the binomial coefficients in a
certain sense. Secondly an upper bound of the tail of the binomial is given,
and the results are then used to derive estimates of pue(ε,C). If a
code is not proper, it would be desirable to have at least subintervals,
where pue(ε,C)
increases, or where it satisfies the 2-r-bound. It is for this
reason that next the range of monotonicity and of the 2-r-bound is
determined. Finally, applications on safety integrity levels are studied.
Keywords: Binary Symmetric Channel, Proper Linear Code, CRC,
Probability of Undetected Error, Weight Distribution, Binomiality,
Monotonicity, 2-r-bound, Dual Distance, Safety Integrity Level
Title
of the Paper: 802.11 Disassociation DoS
Attack Simulation
using Verilog
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Authors:
Baber Aslam, Monis Akhlaq, Shoab A. Khan
Abstract: A number of Denial of Service (DoS) attacks in IEEE 802.11 are due
to unauthenticated/ unencrypted management and control frames. Current IEEE
802.11 simulators deal with Physical and MAC layers and do not include the
exchange of management and control frames, thus making it difficult to
simulate an attack (DoS) and its possible solution. A basic IEEE 802.11
network simulator using Verilog is presented. Basic aim is to design a
simulator using a hardware description language (HDL) such as Verilog, since
the functions and protocols described in state machines are best simulated
using a HDL. Besides simulation of a simple wireless network, the paper also
presents simulation of a spoofed MAC disassociation DoS attack and one of its
possible solutions. The proposed simulator includes the communication setup
process and can be used for simulating other DoS attacks and their possible
solutions.
Keywords: Network Simulator, IEEE 802.11, Verilog, Wireless LAN, Link
layer simulation.
Title
of the Paper: An Efficient Scheduling Mechanism for Simulating Concurrent
Events in Wireless Communications Based on an Improved Priority Queue (PQ)
TDM Layered Multi-Threading Approach
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Authors:
P.
M.
Papazoglou, D.
A.
Karras, R.
C.
Papademetriou
Abstract: The physical activities of a real wireless network are represented
by events which are the main components of a discrete event simulation (DES)
system and are produced by its event generator during simulation time. Each
network service (e.g. voice, data and video) constitutes an event for a
particular mobile user. A critical component within the simulation system,
called scheduler, runs by selecting the next earliest event, executing it
till completion, and returning to execute the next event. Calendar queue is
the state of the art implementation of the scheduler among the most popular
networking simulation tools such as ns-2. However, Calendar queue
time-stamping mechanism presents drawbacks in the case of complex dynamical
systems, like wireless networks, where probability of events concurrency is
large. In such a case sequential time-stamping of calendar queue scheduling
does not reflect real network events occurrence and generation. It should be
remarked that there are very few reports if any in the literature concerning
research on events scheduling mechanisms in such real time systems. On the
other hand, multi-threading technology offers advanced capabilities for
modelling concurrent events. The main goal of this paper is to illustrate
that multithreading architectures provide the means for designing efficient
schedulers in the simulation of wireless networks resource allocation but,
also, several critical issues such as deadlocks, synchronization and
scheduling must be effectively faced. In this paper, a stable simulation
model is presented based on a novel layered thread architecture and on an
alternative network event scheduling mechanism, called the Priority Queue
(PQ) – Time Division Multiplexing (TDM) Layered Multithreading mechanism,
which supports concurrent events as compared to the state of the art approach
which supports only sequential events. Moreover, specific drawbacks of the
JVM multi-threading platform such as thread execution unpredictability are
also faced and presented.
Keywords: cellular network, simulation, event scheduling, concurrent
events, multi-threading
Title
of the Paper: Simulation for Different Order Solitons in Optical Fibers
and the Behaviors of Kink and Antikink Solitons
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Authors:
Mohammad Mehdi Karkhanehchi, Mohsen Oliaee
Abstract: Solitons are obtained by interaction effect of nonlinear effect and
dispersion, so that nonlinear differential equation, KDV, is indicated to
this matter. To understand how solitons are created and propagated, this
equation has to be solved. The solution describes first, second and third
order solitons family. Transmission relation is found by inverse scattering
transform (IST) method. Also, the dynamic behavior of the Kink and Antikink
solitons has been investigated by Sine- Gorden equation in physical systems. This
equation has significant role in various physical branches. In optical fiber,
Kink and Antikink solitons keep their forms when they propagate in fiber
length. Because of indirect loss effect on nonlinear higher order, numerical
simulation of those solitons is necessary. Therefore, Sine- Gorden equation
has to be solved analytically.
Keywords: solitons, optical fiber, nonlinear optics, KDV equation,
Sine-Gorden equation, optical communication
Issue 4, Volume 7, April 2008
Title
of the Paper: Automatic Extraction Method of Airport Object in Aerial
Imagery
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Authors:
Guang Yang, Bai Zhang, Xiaojuan Wang, Zongming Wang, Guoxin Wu
Abstract: Along with the progress of each basic theories in the picture
science, the numerical picture processing technique gets the extensive
application in each section of national economy, moreover, it has become
study hotspot that is automatic identify in panchromatic aerial image. A kind
of MF method to extract airport in aerial image was put forward on analysing
template match and characteristic extraction. It brought forward a template
match method to resolve that because of the information covering to have
great capacity in aviation photograph, the hair stabs ordering more, operating
great, and so on. It obtained the better result.
Keywords: Threshold segmentation, Remote sensing image, Panchromatic
aerial image, Airport object, Image segmentation, Template match,
Characteristic extraction.
Title
of the Paper:
Human Exposure Assessment in the Vicinity of 900 MHz GSM Base Station Antenna
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Authors:
Mimoza Ibrani-Pllana, Luan Ahma, Enver Hamiti,
Ruzhdi Sefa
Abstract: Daily exposure to GSM electromagnetic fields has raised public
concern of possible adverse health effects to people living in the vicinty of
base station antennas. International guidelines and standards established for
limiting human exposure to electromagnetic fields are given in two
categories: Basic restrictions (SAR, induced current density, and induced
power density) and Reference levels (free space electric field intensity,
magnetic field intensity and power density). In order to check compliance for
both categories, in this papers are presented measurements of incident
electric field and obtained results are used for numerical prediction of SAR.
Measurements of field strength and power flux density are performed on
locations few meters away from base station antenna, in different levels,
with and without usage of mobile phones, during day and in peak hours of GSM
system usage. Results are compared with ICNIPR Guidelines, IEEE and CENELEC
standards.
Keywords: base station antennas, field strength, power density, GSM,
measurement
Title
of the Paper: Analysis of Non-Linear Response in DS-CDMA Satellite Systems
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Authors:
Mario Reyes-Ayala, Edgar Alejandro Andrade-Gonzalez, Jose Alfredo Tirado-Mendez, Hildeberto Jardon Aguilar
Abstract: This paper shows an algorithm to calculate synchronous DS-CDMA
satellite links with non-linear response amplifiers, where the probability
error, active device parameters, harmonics, intermodulation products and
back-off compensation, are used to evaluate the performance of the system. The
analysis of carrier to interference ratio is carried out for N-carrier
up-link, where a single carrier uses DS-CDMA.
Keywords: Harmonics, Intermodulation, DS-CDMA, link budget, HPA,
carrier to interference ratio.
Title
of the Paper: Analytic Solution of Nadir Attitude Pointing for LEO
Microsatellite
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Authors:
A.
M. SI Mohammed, M. Benyettou, A. Boudjemai Y. Hashida, M.
N. Sweeting
Abstract: An Analytic solution of Nadir attitude pointing equation of gravity
gradient satellite stabilised is presented. The attitude equation is Euler linearised
equation for near Nadir pointing axially symmetric satellite including only
gravity gradient torque and assuming other torques such as magnetic torque,
aerodynamic torque, solar radiation pressure torque and controller are
constants. The obtained analytical solution was compared to numerical
solution of satellite attitude equation.
Keywords: LEO, Microsatellite, Alsat-1, Analytic, Nadir, Attitude,
Simulation.
Title
of the Paper: An Adaptive Weighted Cluster Based Routing (AWCBRP) Protocol
for Mobile Ad-hoc Networks
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Authors:
S.
Karunakaran, P.
Thangaraj
Abstract: Nodes of Wireless Adhoc networks have restricted bandwidth resource,
and comprise high mobility. It has a high link breakage rate and so
partitioning rate of the network is considerably high. Routing in MANET’s is
very complex because of node mobility and limited communication resource. Topology
changes and breakage of exiting paths occurs repeatedly due to the mobility
of nodes. A routing protocol should quickly adapt to the topology changes and
efficiently search for new paths with minimal power consumption. We propose
an adaptive weighted cluster based routing for mobile ad-hoc networks which
amends swiftly to the topological changes and establishes the routing
efficiently. In our proposed approach, the cluster head selection is
performed by assigning a weight value based on the factors Energy Level,
Connectivity and Stability. We show by simulations, that the performance of
our proposed protocol surpasses the existing adhoc routing protocols in all
aspects.
Keywords: Ad-hoc networks, MANETs, Clustering, Multipath, Routing.
Title
of the Paper: Combination of Service Learning and Pre-Service Teacher
Training via Online Tutoring
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Authors:
Chun Hung Lin, Eric Zhi Feng Liu, Hwa Wei Ko, Shan Shan Cheng
Abstract: During the teacher training process, service learning is an
important element which can improve per-service teachers’ teaching skills and
increase their understanding about their students. This study integrated the
concept of service learning into pre-service teacher training via online
instruction. Fifty-four pre-service teachers participated in this program.
X-learning system, an online tutoring system was provided by Chunghwa
Telecom. Each pre-service teacher taught one rural area student by X-learn
system. Through video record, interviews, and reflective journal, this study
demonstrated how the pre-service teachers taught their students in online
instruction, and what benefit the pre-service teachers gained from
participating in this program.
Keywords: Online instruction, Service learning, Pre-service teacher
training, E-tutor, One-on-one tutoring, X-learn system
Title
of the Paper: Bandwidth Management Method for Heterogeneous Wireless
Network
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Authors:
Hui-Min Huang, Ying-Hong Wang
Abstract: The integration of heterogeneous networks is a trend of Fourth
Generation (4G) systems. But with more integrating network technologies,
bandwidth management is more complicated. This paper proposes a bandwidth
management method, called Bandwidth Management and Disposition (BMD). The BMD
calculates the Reword Point (RP) to quantify the Mobile Host’s (MH) requests,
and calculates the Upgrade Rank (UR) or Downgrade Rank (DR) to quantify the
upgraded or downgraded sequence of bandwidth, respectively. In the future,
when a new service type or network technology is created, the proposed system
functions also can be directly applied. This paper analyzes the BMD is more
feasible than the other existed methods. The simulated results also
demonstrate the functionality of the BMD. The incremental rate of achieved
request is 12.52% and rate of bandwidth usage is 2.4% when the system with
BMD. We conclude that the proposed system facilitates further development of
wireless communication networks.
Keywords: bandwidth management, heterogeneous wireless network,
hierarchical mobility management, Radio Access Technology (RAT), Reword Point
(RP), Bandwidth Management and Disposition (BMD)
Title
of the Paper: Modified Pulse 2.45 Fractal Microstrip Antenna
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Authors:
M. Ismail, H. Elsadek, E. A. Abdallah, A. A. Ammar
Abstract: In this paper, the idea of space-filling properties of the fractal
is used to minimize the area of a microstrip rectangular patch antenna
operating at 2.45GHz. The first iteration is in the form of a pulse and the
study includes the first four iterations. It is found that the second
iteration is the most suitable one because the third and fourth iterations
have inferior antenna parameters. The size reduction in this case is about
15.1%. In order to further reduce the antenna size many trials have been
carried out. These trials include adding a shorting wall, adding an air gap,
adding a shorting wall and an air gap together, adding a shorting wall (or
pins) together with an air gap and inverting the patch. As a consequence
46.12 % reduction in size is obtained with reasonable antenna gain. The
designed antennas were fabricated on Teflon dielectric substrates and good
agreement is found between simulated and measured results.
Keywords: Fractal, Microstrip antenna, Space-filling, and Size
reduction.
Title
of the Paper: Using TETRA for Remote Control, Supervision and Electricity
Metering in an Electric Power Distribution System
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Authors:
Igor Ozimek, Tomaz Javornik, Gorazd Kandus, Milan Svajger
Abstract: An important part of the communication infrastructure in systems
that cover large geographic areas and require maintenance and management of
devices on remote locations - such as electric power distribution systems -
is mobile radio communication. This is especially important on remote
locations with no other communication means available. Besides the
traditional voice communication, the new digital PMR systems also support
various modes of data communication including the IP protocol. This offers
new possibilities for remote data applications. In our paper, the
possibilities of using a TETRA system for remote data applications such as
remote control and supervision of breakers and disconnectors, and remote
electric meter reading, are analyzed for the case of the electric power
distribution company Elektro Ljubljana, d.d.
Keywords: electric power distribution, remote metering, automated
circuit breakers, PMR, TETRA
Title
of the Paper: Collaborative Middleware on Symbian OS via Bluetooth MANET
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Authors:
Feng Gao,
Martin Hope
Abstract: In this paper we explore the possibility of using Bluetooth in the
development of a Mobile Ad-Hoc Network (MANET) suitable for transmitting data
between Symbian OS based Smartphone’s. We also analyse the problems that
Bluetooth presents when considering existing MANET routing protocols. Then,
we present the design of a collaborative application engine by making
allowances for the restrictions associated with Bluetooth and finally we
review our current progress and consider future work.
Keywords: Bluetooth, Wireless, Collaboration, Symbian OS, MANET
Title
of the Paper: A Channel Model of Atmospheric Impairment for the Design of
Adaptive Coding and Modulation in Stratospheric Communication
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Authors:
Gorazd Kandus, Mihael Mohorcic, Miha Smolnikar, Erich Leitgeb,
Tomaz
Javornik
Abstract: Wireless communication in the millimetre frequency bands is subject
to severe atmospheric impairment caused by rain and scintillation, which may
occasionally cause deep fades and thus needs to be mitigated by an efficient
countermeasure such as adaptive coding and modulation (ACM). In this paper we
focus on stratospheric communication and propose appropriate rain and
scintillation fading channel models, which we use to describe the conceptual
design of adaptive coding and modulation on four reference theoretical ACM
schemes. Rain fading is modelled according to the modified DLR segment
approach for generating channel attenuation time series, taking into
consideration the specifics of stratospheric communication systems, namely
the variable elevation angle and different carrier frequency. Additional
fading due to scintillation, which may be harmful in deep fades caused by the
rain, is modelled by adjusting the satellite scintillation channel model so
that the amount of scintillation fading is correlated to the attenuation
caused by the rain. We describe two extreme approaches to the ACM design
process, one for maximizing the system reliability and the other for
maximizing the system throughput. We present simulation results for four
representative theoretical ACM schemes with different SNR ranges as the
variation of bandwidth efficiency in time, and as system outage probability. Finally
we show that, for a given SNR range, increasing system complexity by
increasing the number of different coding-modulation (CM) modes beyond a
certain optimum value does not yield a notable increase in bandwidth
efficiency. In other words, there is a trade off between the system
complexity and bandwidth efficiency that needs to be taken into account when
designing the ACM scheme. Finally, two standards with ACM schemes applicable
for stratospheric communications are proposed and analyzed, namely IEEE
standard 802.16 for single carrier transmission and ETSI standard for digital
video broadcasting over satellites DVB-S2.
Keywords: rain fading, scintillation fading, millimetre frequency
band, stratospheric communication system, propagation channel model, adaptive
coding and modulation
Title
of the Paper: Indoor Information Support System Using Optical Wireless
Communications Technique
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Authors:
Xin Lin, Kazutaka Kosugi, Hideo Itoh
Abstract: Optical wireless communications system with a corner-reflecting
terminal and a distance image camera is proposed for location-based
information support. By using the corner-reflecting terminal and the distance
image camera, the user location can be tracked and detected, and the distance
from the camera to the user who is tracked can be obtained real-timely. Therefore,
the information support of users can be implemented based only on their
physical locations and without the private data such as an address or ID
number. We also performed several experiments based on the proposed system
and method, and their effectiveness is demonstrated in multi-terminal
location detection and indoor data communications.
Keywords: Optical wireless communication; Location based;
Corner-reflecting terminal; Distance image camera; Three-dimensional location
detection; User information support.
Title
of the Paper: The Dual Distance of a CRC and Bounds on the Probability of
Undetected Error, the Weight Distribution, and the Covering Radius
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Authors:
H. D.
Wacker,
J.
Boercsoek
Abstract: Dual codes play an important role in the field of error detecting
codes on a binary symmetric channel. Via the MacWilliams Identities they can
be used to calculate the original code’s weight distribution and its
probability of undetected error. Moreover, knowledge of the minimum distance
of the dual code provides insight in the properties of the weights of a code.
In this paper firstly the order of growth of the dual distance of a CRC as a
function of the block length n is investigated, and a new lower bound is
proven. Then this bound is used to derive a weaker version of the 2-rbound on
the probability of undetected error, and the relationship of this bound to
the 2-r-bound is discussed. Estimates of the range of binomiality and the
covering radius are given, depending only on the code rate R and the degree r
of the generating polynomial of the CRC. In the case of a CRC, two results of
Tietäväinen are improved. Furthermore, wit is shown that there is binomial
behavior of the weight distribution, if only n is large enough. Then, by
means of an estimate of the tail of the binomial, another bound on the
probability of undetected error is verified. Finally a new version of
Sidel’nikov’s theorem on the normality of the cumulative distribution
function of the weights of a code is presented, where the dual distance is
replaced by an expression depending on n and the degree r. In this way the
conclusions of the present paper may attribute a new meaning to some well
known results about codes with known dual distance and give some new insight
in this kind of problems.
Keywords: CRC, Binary Symmetric Channel, Probability of Undetected
Error, Weight Distribution, MacWilliams Identities, Binomiality, Dual
Distance, Gaussian Distribution, Covering Radius, Sidel’nikov’s theorem.
Issue 5, Volume 7, May 2008
Title
of the Paper:
The Importance of Location on Trust in Mobile Networks
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Authors:
Dagmara Spiewak, Volker Fusenig, Thomas Engel
Abstract: Mobile wireless networks introduce new challenges regarding
security and privacy of data. On the other hand self-organization and
independence of fixed infrastructure make these networks, such as mobile
adhoc networks (MANETs) very attractive for military but also civilian
application areas. They allow to extend the wireless link into areas with no
readily available communication infrastructure. Additionally, these networks
can also be used as a subsequent to the common communication environment in
order to assure communication on-the-fly even if the regular network is
overwhelmed, like for instance during emergency situation or during major
sports or cultural events. With the purpose to overcome the security problem
accompaingned with these networks, more and more research is launched in the
area of Trust establishment in mobile wireless networks. However Trust in
mobile network settings introduces new challenges compared to the
conventional notions for infrastructure networks. Especially mobile behavior,
which is enabled by wireless links, diversifies Trust research in multiple
ways. Hence unfortunately, traditional security concepts, such as Public Key
Infrastructures are no accurate solutions to protect sensitive communication
and data in these autonomous network environments. Our paper discusses the
Trust establishment in mobile wireless networks. We introduce the idea of
TrustRings which enables the calculation of Trust-Values for nodes in mobile
wireless networks based on an egocentric network model. Furthermore, the
model takes the location and distance between communicating entities into
account in order to obtain the accurate Trust-value.
Keywords: Trust, Security, Mobility, MANETs, Network Model
Title
of the Paper: High K Dielectric Resonator Antenna
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Authors:
Nicolaescu Ioan, Ioachim Andrei, Toacsan Irina, Radu Ionut, Banciu
Gabriel, Nedelcu Liviu
Abstract: The microwaves are used for both civilian and military applications
for communications and detection. In the communication area, the endeavours
of the scientist are focused to increase both the quantity and the quality of
the data send over a communication link. The need to increase the amount of
data that can be handled by a communication system is requested by the desire
to use a communication device not only for voice but also for data, images,
pictures and video transmission. Sending video over a communication link
needs more bandwidth, which may be provided by increasing the operational
frequency. In this way the frequency range of communications systems have
extend from hundreds of KHz to MHz and now to microwaves (ISM band, IEEE
802.11 standard, Wi-MAX etc). The quality of the data is assured by improving
the processing methods such as modulation, different methods of coding for
digital systems, spatial processing (MIMO systems etc) etc. In addition to
increased demand for bandwidth and quality there is a strong requirement for
multifunction and miniaturised communication devices, which can be provided
by using special designed microwave materials. In the field of detection
devices the applications range from radar systems to microwave imaging
systems, anti-collision systems, ground penetrating radar etc. In this case,
the miniaturisation is a very important issue, too. As it is know the size of
different kind of microwave components is in a certain relation with the
wavelength divided by root square of the dielectric permittivity. Therefore,
the size of the microwave component can be decreased by increasing the
dielectric permittivity. Dielectric materials based on TiO2 are suited for
applications in electromagnetism and optics due to their nonlinear
properties, their high value of the dielectric permittivity and their
temperature behaviour. The paper describes very shortly the technology
applied to manufacture high dielectric permittivity materials based on TiO2
and a dielectric resonator antenna manufactured with these materials. The
experimental data measured for dielectric antenna are presented.
Keywords: high K dielectric materials, dielectric resonators, antennas
Title
of the Paper: Association between Facial Expressions and Symbolic Images
among Different Educational Backgrounds
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Authors:
I-Tsen Liu, Chung-Shan Sun
Abstract: A series of biological changes happens when people have emotions,
such as short breath, sweating, blush, rapid heartbeat, increasing blood
pressure. Thus, many areas could be evolved in studying emotions, and this
study proposed to investigate the relationships between facial expressions
and visual images. This study proposed to investigate the effect of different
educations in the cognition of facial expressions and symbolic expressions of
emotion. Four hundred students with different genders from four departments
were recruited in this study. The results suggested some facial expressions
could be perceived differently because of different gender or educational
background. The most important difference between facial expressions and
symbolic expressions of emotion is that facial expression is more imitated
and more accurately deliver the real mind states. However, the symbolic
expressions of emotion are more stereotypic and hard to represent the details
of a facial expression.
Keywords: facial expressions, symbolic expression of emotion, symbolic
image.
Title
of the Paper: Analysis of Burst Acknowledgement Mechanisms for IEEE
802.11e WLANs over Fading Wireless Channels
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Authors:
Jain-Shing Liu
Abstract: Transmission opportunity, or TXOP, is a channel control method
introduced in the IEEE 802.11e wireless local area network (WLAN) standard. The
control method includes some new operations developed for improving channel
efficiency. In this paper, we propose an analytical model to evaluate these
TXOP operations under fading channels. With this model, we calculate the
maximum achievable throughput for the IEEE 802.11 DCF with RTS/CTS access
mode. In addition, we quantify in the experiments how these operations can
affect the system efficiency for different environments. The experiment
results well confirm the theoretical model that provides new insights on
design criterion for a WLAN in the real world.
Keywords: WLAN, TXOP, Burst Transmission, Acknowledgment Aggregation,
Performance Analysis.
Title
of the Paper: Cell Planning in GSM Mobile
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Authors:
Jalal Jamal Hamad-Ameen
Abstract: Cell planning in GSM mobile system is one of the most important
operations must be done before the installation of the system, cell planning
means studying the geographic area where the system will be installed and the
radius of each BTS coverage and the frequencies used. Like other
communication systems the GSM mobile has the frequency band used in the
systems depends on the type of the GSM system, cellular system means dividing
the area region the system installed in it in to many cells, each cell and
each channel must has it’s own frequency, so the frequency planning is very
important to the future of the system installed because of continuously
expanding the area of each city and increasing the users of GSM system, the
frequency band for the system is limited, so it must be taken account the
number of frequencies using, in this paper, cell planning before installing
the system has been studied and the advantages of this process for system
future installed in that area has been shown by some examples.
Keywords: GSM Mobiles, Cellular system, Clusters, Frequency reuse.
Title
of the Paper: Analysis,
Design, and
Simulation of a Log Periodic Antenna
for Mobile Communication
Bands
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Authors:
Jaleel Azeez Hamadameen
Abstract: The Log-Periodic Loop Antenna (LPA) is investigated as a new type
of antenna, whose properties vary periodically with the logarithm of
frequency, and provides wide bandwidth, broad beam width, and high gain. This
antenna has smaller transverse dimensions than another antenna types. In this
paper the analysis, design, and simulation of log periodic dipole antenna
(LPDA) is presented, which is suitable and particular for mobile
communication bands from 1150 MHz up to 2450 MHz. ZPLOTS simulation program
shows acceptable results and confirm the theoretic basics.
Keywords: Log periodic antenna, mobile communication.
Title
of the Paper: A Routing Protocol for
Throughput Enhancement and Extend
Network Lifetime in MANET
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Authors:
GunWoo Park, SangHoon Lee
Abstract: Unlike a cellular network, MANET(Mobile Ad-hoc Networks) is
constructed only by mobile nodes without access point. Since MANET has
certain constraints, including power shortages, an unstable wireless
environment, and node mobility, more power-efficient and reliable routing
protocols are needed. Namely, it is very important that we consider Residual
Battery Capacity and also Link Stability at the same time in MANET. Accordingly,
this paper proposes RPTnE(A Routing Protocol for Throughput Enhancement and
Extend Network Lifetime in MANET). The RPTnE considers Residual Battery
Capacity and Link Stability. The RPTnE is based on AODV(Ad-hoc On-demand
Distance Vector Routing). We use ns-2 for simulation. This simulation result
shows that RPTnE is able to enhance throughput and extend network lifetime
through the reduction of power consumption and distribution of traffic load
that is centralized into special node.
Keywords: Throughput, Network Lifetime, Residual Battery, Signal
Strength, Distance
Title
of the Paper: Research of the ARP Spoofing Principle and a Defensive
Algorithm
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Authors:
Yang Liu, Kaikun Dong, Lan Dong, Bin Li
Abstract: During the network communication process, attacker carry on ARP
spoofing by using the disadvantage of the ARP(Address Resolution Protocol)
protocol, this phenomenon is seriously threaten the LAN security. This paper
will introduce the commonly used ARP spoofing methods such as
internal/external network sniffing, interception, malicious attack and so on.
It presents the Matching IP method, Data monitor method, Echo time method,
ARP response analysis method, software tools detecting method as well as the
new method of ARP cache updating, using switching equipment to control and
other strategy and presents the algorithm to keep ARP spoofing away and
maintain network security.
Keywords: ARP spoofing, interception, monitor, MAC, sniffing, guarding
algorithm
Title
of the Paper: Distributed Video Coding in Wireless Multimedia Sensor
Network for Multimedia Broadcasting
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Authors:
Zhuo Xue, K.
K. Loo, J. Cosmas, P.
Y. Yip
Abstract: Recently the development of Distributed Video Coding (DVC) has
provided the promising theory support to realize the infrastructure of
Wireless Multimedia Sensor Network (WMSN), which composed of autonomous
hardware for capturing and transmission of quality audio-visual content. The
implementation of DVC in WMSN can better solve the problem of energy
constraint of the sensor nodes due to the benefit of lower computational
encoder in DVC. In this paper, a practical DVC scheme, pixel-domain Wyner-Ziv(PDWZ)
video coding, with slice structure and adaptive rate selection(ARS) is
proposed to solve the certain problems when applying DVC into WMSN. Firstly,
the proposed slice structure in PDWZ has extended the feasibility of PDWZ to
work with any interleaver size used in Slepian-wolf turbo codec for
heterogeneous applications. Meanwhile, based on the slice structure, an
adaptive code rate selection has been proposed aiming at reduce the system
delay occurred in feedback request. The simulation results clearly showed the
enhancement in R-D performance and perceptual quality. It also can be
observed that system delay caused by frequent feedback is greatly reduced,
which gives a promising support for WMSN with low latency and facilitates the
QoS management.
Keywords: Wireless Multimedia Sensor Network, Distributed Video
Coding, Wyner-Ziv video coding, Laplacial Distribution, RCPT.
Title
of the Paper: Feedback in Soft Input Decryption
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Authors:
Natasa Zivic, Christoph Ruland
Abstract: This paper develops further the idea of use of Soft Input
Decryption. The function of Soft Input Decryption is to integrate decryption
into the decoding process. In this paper it is shown how Soft Input
Decryption can be enhanced using feedback from the channel decoder. In this
way, the cooperation between channel coding and cryptography is further
develops. The effect of the feedback is explained on an example of the
trellis diagram. Like in Soft Input Decryption, also in feedback method is
the usage of reliability L-values of SISO channel decoder of great
importance. Theoretical analysis, as well as results of computer simulations
have been presented and discussed.
Keywords: Soft Input Decryption, feedback, L-values, cryptographic
check values, MAP, SISO Channel Decoding, trellis
Title
of the Paper: Probability Density Function of M-ary FSK Signal in the
Presence of Noise, Interference and Fading
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Authors:
Dragana Krstic, Mihajlo Stefanovic, Natasa Kapacinovic, Srdjan Jovkovic,
Dusan Stefanovic
Abstract: In this paper the receiver for the demodulation of M-FSK signals in
the presence of Gaussian noise, intersymbol interference, impulse
interference and fading is considered. The probability density function of
M-ary FSK signal in the presence of noise, interference and fading is
derived. These interferences can seriously degrade the communication system
performances.
Keywords: M-ary Frequency Shift Keying, Gaussian Noise, Intersymbol
Interference, Impulse Interference, Rayleigh Fading, Nakagami Fading,
Probability Density Function, Joint Probability Density Function
Title
of the Paper: Performance Evaluation of SIP Based Handover in
Heterogeneous Access Networks
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Authors:
Rok Libnik, Ales Svigelj, Gorazd Kandus
Abstract: Wireless technologies evolve very fast in last years. In the future
operators will need to enable users to use communication's services
independent from access technologies, thus they will need to support
handovers between different networks. In this paper we presented simulation
results for handover from WLAN network to HSDPA network and vice versa. We
used IP telephony application with SIP signalization. We proposed new
approach, which is more applicable to real operator environment as assures
proper billing during handover. The handover was executed using simple
decision function, based on received signal measurement. To achieve more
credible results we used characteristics of real operator's networks. Simulation
results show that both handovers i.e. from WLAN to HSDPA network and from
HSDPA to WLAN network have some limitations which can affect the quality of
service especially for real-time application, like VoIP. With result we also
shoved that characteristics of today’s networks are not good enough to offer
seamless handover using SIP protocol and that mobile packet wireless networks
will need to improve to offer lower latencies.
Keywords: Heterogeneous networks, SIP, Seamless handover, Mobility
management, Performance evaluation, Real-time applications
Title
of the Paper: A Review
for Uniqueness
and Variations
in Throughput
of MANET Routing Protocol
due
to Performance Metrics, Characteristics
and
Simulation Environments
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Authors:
M.
Sulleman Memon, Manzoor Hashmani, Niaz A.
Memon
Abstract: Very prestigious work has been performed in the field of mobile ad
hoc networks (MANETS) with respect to their routing protocols. Researchers
have developed and designed so many protocols for these networks, but due to
the dynamic change in topology, decentralization, power management, bandwidth
and many other factors like these no specific routing protocol is exclusively
recommended, up to today, which comply and fulfill all the needs and
requirements of users for ad hoc networks in all situations of network
variation statuses and traffic overhead. This paper contributes an effort
towards anthology of one of the major segment of routing protocols i.e.
unicast, their categories and the main type of unicast routing protocols such
as DSDV from proactive plus DSR from reactive. The protocols and their
performances are evaluated on the basis of some metrics commonly used in support
of simulation environment for getting simulation results acquired by
simulation of certain model with some parameters with the help of NS-2, OPNET
and GloMoSim like simulators. The performance evaluations are declared on the
basis of those simulations results, but all the results peter out when
magnitudes of those attributes or load of network changes (increased or
decreased ) with respect to bandwidth, power management, end to end delay,
data errors, packet dropping ratio or even with distance. Here in this paper
we have scrupulously reviewed the work done on these protocols and majority
of the simulated results are examined and finally suggest few common
uniqueness and differences with respect to their properties which remain
unchanged in all the situations and scenarios.
Keywords: Multicasting Capability, Route Metric, Beaconing, QoS
Support, Structure, Security Support
Title
of the Paper: Reverse Shortest Path for Dataflow Optimization of
Hierarchically Structure Data Networks
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Authors:
Prawat Chaiprapa, Kajornsak Kantapanit
Abstract: In the routing process to select the data paths for Hierarchically
Aggregation/Disaggregation and Composition/ Decomposition,(HAD) networks, a
fast algorithm for finding optimum paths for dataflow is needed. In this
research we propose an algorithm called the Reverse Shortest Path algorithm
to improve the speed in the calculating procedure for finding the shortest
paths. This algorithm performs the reversed calculation in stead of the
forward calculation used in conventional algorithms. The demand in each
original destination pair (OD pair) has been distributed to the sub OD pairs
in each relevant subnetwork r(u;v) = r(u;l) = ::: = r(l;k) = r(k;v) with l
and k, the gateways and ancestors in the active path. For each different
commodities, the parallel processing is carried out with the shared shortest
path processing time of O(log(n)) which less than O(mlog(n)) of HAD
algorithm[1] where, n is the number of nodes in the networks, M is the number
of commodities in each cluster and m is a positive integer which is less than
M. The proposed algorithms have been developed and tested on a simulated
network of 200 nodes clustered into 20 groups. Each group uses a personal
computer as the processor for the group. Ten data Monte Carlo simulation
patterns were generated for the test. The first five patterns represent
typical normal dataflows which largely consist of short distance
communications. The other five patterns represent the worst case data
communication scenario. Test results on the proposed Reverse Shortest Path
algorithm show that, for the tested network, the algorithm has improves the
speed in finding the shortest paths by 20% as compared to the conventional
shortest path algorithm.
Keywords: Optimal routing,distributed computation, gradient projection
method, hierarchically structure network
Title
of the Paper: Target Detection and Offline
Analysis of RADAR
Data from
MIL-STD-1553B
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Authors:
N.
K. Srinath,
P.
Ramakanthkumar, G. Prabhushankar
Abstract: The proposed system entitled ‘‘Target Detection and Offline
analysis of RADAR data from MILSTD- 1553B’’ will detect the target, plots the
position on the screen and help the pilots, test engineers and RADAR
evaluation team during offline. The path of the TARGET and HOST/HACK
aircrafts are analyzed along with navigation specific parameters. The system
has the mechanism to save the HOST/HACK and TARGET information during flight.
The system will also work in on-line mode. During the on-line mode the TARGET
information is detected by the RADAR and is available on MIL-STD-1553B Bus. Using
the Bus Monitor (BM) mode the relevant data is extracted. Using this data the
flight position of the TARGET aircrafts are calculated. In off-line the
recorded data’s are used to calculate the positions of the aircrafts and the
paths of the aircrafts. It is plotted on the map in a graphical window. All
the navigation details of the aircraft are displayed on a tote window for
RADAR data analysis purpose.
Keywords: RADAR, MIL-STD-1553B, UHF, TDMA, TARGET
Title
of the Paper: Analysis of Opposing Stream Effect on the Non-uniform
Optical Fiber Communication Lines
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Authors:
Mohammed Yousef Al-Gawagzeh,
Amjad Yousef Hendi
Abstract: In this paper we define the expression for definition the opposing
stream in optical fiber lines with N heterogeneities. The opposing stream
dependence on the values and number of heterogeneities has been carried out. It
was found that, the calculation of opposing stream in optical fiber lines
with N heterogeneities can be limited by four-five heterogeneities which are
nearest to the transmitting end.
Keywords: Optical fiber, Opposing stream, Heterogeneity, Non-uniform,
Wave reflection,
Title
of the Paper: Web 2.0 Proxy: Upgrading Websites from Web 1.0 to Web 2.0
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Authors:
Yung-Wei Kao, Ming-Chih Hsieh, Sheau-Ling Hsieh, Shyan-Ming Yuan
Abstract: Since the term “Web 2.0” appears,
a new generation of Web is coming. There are many articles referring to how
to design a Web 2.0 website. However, the traditional Web 1.0 websites are
still multitudinous currently. The developers of the traditional Web 1.0
website may not have adequate techniques to reconstruct the websites into Web
2.0 timely. Rebuilding a website often takes tremendous efforts. A simple and
effective strategy to upgrade the websites is essential. The paper attempts
to provide a flexible framework, by introducing the Web 2.0 Proxy, to upgrade
websites from Web 1.0 to Web 2.0. The Web 2.0 Proxy combines the original Web
1.0 web page with the additional Web 2.0 information together on the fly. Therefore,
the developers need not to rewrite their websites, and the users are able to
experience the additional Web 2.0 functions. In the paper, we have
implemented the tag and comment functionalities of Web 2.0.
Keywords: Web 2.0, Proxy,
web page
Title
of the Paper: On Coexistence and Spectrum Sharing between IMT-Advanced and
Existing Fixed Systems
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Authors:
Zaid A. Shamsan, Lway Faisal, Tharek Abd Rahman
Abstract: This paper looks into coexistence and sharing between systems as a
recently critical issue due to emerging new technologies and spectrum
scarcity. At WRC-07, ITU-R allocated 3400-3600 MHz band for the coming fourth
generation (4G) or IMT-Advanced on a co-primary basis along with existing
Fixed Wireless Access (FWA) systems. Therefore, coexistence and sharing
requirements like separation distance and frequency separation coordination
must be achieved in terms of both co-channel and adjacent channel
frequencies. Co-sited the two base stations antennas and non co-sited
coexistence of the twos systems are investigated. The interference analysis
models, adjacent channel interference ratio ACIR and spectrum emission mask
are applied in the mentioned band to extract the additional isolation needed
to protect adjacent channel interference. Also interference to noise ratio as
a standard interference criteria is introduced and possible engineering
solutions are suggested and explained at last.
Keywords: ACIR, ACLR, ACS, Additional isolation, Co-sited and non
co-sited coexistence, FWA systems, IMT-Advanced system, Interference.
Title
of the Paper: Research of the ARP Spoofing Principle and a Defensive
Algorithm
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Authors:
Yang Liu, Kaikun Dong, Lan Dong, Bin Li
Abstract: During the network communication process, attacker carry on ARP
spoofing by using the disadvantage of the ARP(Address Resolution Protocol)
protocol, this phenomenon is seriously threaten the LAN security. This paper
will introduce the commonly used ARP spoofing methods such as
internal/external network sniffing, interception, malicious attack and so on.
It presents the Matching IP method, Data monitor method, Echo time method,
ARP response analysis method, software tools detecting method as well as the
new method of ARP cache updating, using switching equipment to control and
other strategy and presents the algorithm to keep ARP spoofing away and
maintain network security.
Keywords: ARP spoofing, interception, monitor, MAC, sniffing, guarding
algorithm
Title
of the Paper: Time Synchronizing Signal by GPS Satellites
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Authors:
Maryam Sadeghi, Majid Gholami
Abstract: In many industrial and trading activities such as navigation,
mapping, power distribution, telecommunication, weather station, digital
radio, industrial control systems and research centers,… one of the main
exchanged information which has been transferred between different parts is
time tag, indicats the precise time of action taking place. Synchronization
between these tags is the main portion of these systems. With transmitting
the time synchronizer signal in determined timing intervals to all of these
sections by one common reference, synchronization will be done. This common
reference could be accessed by GPS Satellites. In this approach GPS
satellite, timing signals, Golden Code, methods of coding and decoding of GPS
satellite signals will be introdused. Synchronizing time with precise time
calculation on GPS receivers, system simulation in MATLAB from GPS satellite
transmitter to receiver and implementing the receiver hardware will be
discussed.
Keywords: PRN Code, QPSK, Synchronization, Spread Spectrum, Almanac,
Ephemeris, C/A & P(Y) code
Issue 6, Volume 7, June 2008
Title
of the Paper: Radiation Pattern Synthesis from Various Shaped Reflectors
Base on PO and PTD Methods for Point-to-Multipoint Applications
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Authors:
Vanvisa Thaivirot, Piyaporn Krachodnok, Rangsan Wongsan
Abstract: This paper presents the shaped reflector antenna by using
backscattering technique to achieve the completely broad-beam radiation
pattern. The radiation synthesis method for shaped reflector that has to
illuminate a predefined circular area are presented by using a variety of
discretization of elementary geometrical functions such as, triangular,
quadratic, circular, guassian, cosine, squared cosine, parabolic and
hyperbolic distributions. The antenna characteristics i.e., maximum ripple
level, maximum gain, and half-power beamwidth (HPBW) of the variety of shaped
reflectors are analytically determined by using physical optics (PO). These
shapes reflector will be discussed on merit and demerit to choose for utilization
in wireless local area network (wireless LAN). The reflector which has
appropriate characteristics for indoor wireless LAN in very large room will
be analyzed detail by introducing the fringe wave (FW) in physical theory of
diffraction (PTD). Having confirmed the validity of this approach, the X-band
antenna prototype is designed and developed. The proposed antenna is tested
experimentally and shows good performance.
Keywords: Vanvisa Thaivirot, Piyaporn Krachodnok, and Rangsan Wongsan
Title
of the Paper: Data Expression Methods in Enterprise
Application using J2EE
Architecture
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Authors:
Zhang Xiaoshuan,
Chen Peijun, Zhao Ming
Abstract: With use of the Internet, web browser-enabled software applications
are developed rapidly. Nowadays enterprises are paying more attention than
ever on developing their business on the Web. The demand for rapidly
delivering high quality web enabled software applications to the end users is
high. The enterprise software developers are making efforts to develop the
enterprise software applications that not only satisfy the business needs but
also achieve the high quality within a short development process. However,
the enterprise software development is normally complicated. For example,
factors like the different enterprise environment, the critical business
demand, the lack of knowledge and experience from the developers and so on
can make the enterprise software development become rather hard work. Under
such circumstances, something is needed to simplify the enterprise software
development and also enable the sharing of the knowledge and experiences
among the different developers. J2EE architecture is becoming the mainstream
framework to develop the more complex enterprise application. The important
problem arises, which is how to manage to each layer in J2EE and control the
interior business data and the customer data, given that J2EE architecture
has many complicated layers. There is respective data presentation in
relevant layer of J2EE, with strictly rules to access and transform data
objects between these layers. This paper adopts the case study method to
discuss the data expression of J2EE and the detailed data expressing methods
in corresponding layer with some instances. According to the Façade pattern
of J2EE, it should control the access to data persistence layer seriously to
protect important enterprise data and avoid showing database pattern to
client directly. The data persistence layer hides behind the business logic
layer and provide business interfaces via the business logic layer to
communicate with the presentation layer to package the data persistence
layer, separates the data persistence layer from the presentation layer.
Keywords: Zhang Xiaoshuan,Chen Peijun, Zhao Ming
Title
of the Paper: Mobile Devices and Data Synchronization Assisting Medical
Diagnosis
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Authors:
Adrian Sergiu Darabant, Horea Todoran
Abstract: In order to be able to establish the most accurate diagnostics as
quick as possible, medical doctors need fast access not only to the current
patient state and test results but also to its historical medical data. With
the diversity of the malady symptoms today a correct diagnostic often
requires a valuable time that is not always available due to the patient’s
condition. Even more, after finishing his/her investigation, the medical
doctor should be able to immediately forward the relevant results to other
medical personnel (doctors, nurses, hospital administration). In this paper
we propose a mobile solution for assisting medical doctors with complete
information about their patients even when outside of the medical centers. The
software aim is assist medical doctors in two main directions: consult
patient data and update the patient’s file and propose early in time new
countermeasures for improving its status. The first direction deals with
providing complete information on the patient’s history, current status, test
results and similar symptomatic cases with their solutions. The second
direction deals with patient information updates. All this will be
implemented in a mobile solution using handheld devices. The goal of our
paper is to present a pilot implementation of a medical database system with
dynamic and efficient data synchronization using wireless technologies.
Keywords: mobile applications, wireless data synchronization, personal
digital assistants, medical applications.
Title
of the Paper: Location Aware Self-Adapting Firewall Policies
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Authors:
Tugkan Tuglular
Abstract: Private access to corporate servers from Internet can be achieved
using various security mechanisms. This article presents a network access
control mechanism that employs a policy management architecture empowered
with dynamic firewalls. With the existence of such an architecture, system
and/or network administrators do not need to reconfigure firewalls when there
is a location change in user settings, reconfiguration will be automatic and
seamless. The proposed architecture utilizes dynamic firewalls, which adapt
their policies according to user locations through the guidance of a policy
server. This architecture is composed of a VPN client at user site, a domain
firewall with VPN capabilities, a policy server containing a policy decision
engine, and policy agents residing in dynamic firewalls, which map policy
server decisions to firewall policy rules, at server site.
Keywords: Network Access Control, Firewalls, Firewall Policies, VPN,
Location Awareness, XACML, Policy Agents.
Title
of the Paper: A Diameter-Constrained Network Reliability model to
determine the Probability that a Communication Network meets Delay
Constraints
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Authors:
Louis Petingi
Abstract: In this paper we provide a summary of results and applications
pertaining a Diameter-constrained Network reliability model. Classical
network reliability models measure the probability that there exist end-toend
paths between network nodes, not taking into account the length of these
paths. For many applications this is inadequate because the connection will
only be established or attain the required quality if the distance between
the connecting nodes does not exceed a given value. The Diameter-constrained
reliability of a network (DCR) introduced recently considers not only the
underlying topology, but also imposes a bound on the diameter, which is the
maximum distance between the nodes of the network. We present a synopsis of
the known results and applications of the DCR for networks that can either be
modeled by directed as well as undirected graphs. Moreover important
combinatorial and computational properties of this reliability measure are
discussed. As the DCR subsumes the classical reliability measure (i.e., where
no distance constraints are imposed on the paths connecting the nodes), as a
by-product we prove well-known classical results.
Keywords: Reliability, networks, diameter, computational complexity,
delay constraints, domination.
Title
of the Paper:
Image Transmission Quality Analysis over Adaptive BCH Coding
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Authors:
Lamia Chaari, Mohamed Fourati, Nouri Masmoudi, Lotfi Kamoun
Abstract: Image communication over telephone wireline and wireless networks
is becoming a standard way of communication due to very efficient compression
algorithms for reducing the required channel capacity. However, all standard
compression techniques are strongly sensitive to channel noise. For noisy
channels it is necessary to investigate in order to select the appropriate
channel coding method as a tradeoff between the image quality and the ability
to control errors caused by noise. BCH (Bose, Chaudhuri, Hocquenghem) codes
are becoming more frequently used due to the availability of VLSI components.
BCH codes have a powerful random and burst correcting ability. BCH codes also
leave the data in its original form which allows image and video decoders to
be specified with "optional" error correction. In order to overcome
the outlined drawbacks of fixed channel protection, Adaptive Protection is
needed. AP adds redundancy as a function of the current channel
characteristics. The BCH code can be adapted towards the burst error
correcting capabilities and this will be shown in the contribution. This
paper investigates the effects of noiseinduced transmission errors on the
performance of BCH coding methods for different errors correction capability.
First, the relations among the bit error rate, signal-to-noise ratio (SNR),
and code lengths are analyzed. Further, the transmission performance of BCH
codes association with different modem schemes are analyzed. QCIF image
transmission quality over BCH codes for different errors capability are
simulated, discussed and compared. The results listed in this article denote
the effects of the using BCH codes in a selected method. Based on this
analysis an adaptive BCH scheme is proposed to pick the correcting
capabilities that offers the best reconstructed image quality for each
average SNR.
Keywords: BCH , QCIF image, transmission, AWGN, PSNR performance,
adaptive.
Title
of the Paper: Redundant Data Transmission and Nonlinear Codes
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Authors:
H. D. Wacker, J. Boercsoek, H. Hillmer
Abstract: In their paper the authors investigate redundant data transmission
protected by arbitrary (not necessarily linear) codes. They generalize
results known so far for linear codes, in particular for cyclic redundancy
checks (CRCs). They use the concept of the Generalized Erasure Channel (GEC)
to determine the probability of undetected error for some binary symmetric
and non-symmetric channels protected by appropriate encoding procedures. In
detail, they investigate communication via different Binary Symmetric
Channels (BSCs), Generalized Erasure Channels and Symmetrized Binary Non
Symmetric Channels (BNSCs). Simple upper bounds are given, relating the new
formulas to that one of the BSC, and the channel capacities are calculated. Finally
the results in connection with an inequality for proper codes are applied to
multi channel coloured transmission via laser beams propagating through Polymer
Optical Fiber (POF).
Keywords: nonlinear code, CRC, Binary Symmetric Channel, Erasure
Channel, Non Symmetric Channel, Probability of Undetected Error, Weight
Distribution, Channel Capacity, Proper Code, Wavelength Division
Multiplexing, Semiconductor Lasers
Title
of the Paper: Achieving
Weighted Fairness in IEEE 802.11-based WLANs:
Models and Analysis
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Authors:
Jain-Shing
Liu
Abstract: In this paper, we consider the problem of providing weighted
fairness among multiple priority classes in a IEEE 802.11-based wireless
local area network (WLAN). An enhanced DCF method is proposed to properly
control the transmission probability of a node that can reflect the weighted
fair share among the data traffic flows in the multi-class environment. For
this method, we present an analytical model to obtain its throughput
performance and the transmission probability capable for the fairness. We
numerically evaluate the method with different simulation scenarios. The
results well validate the proposed method that can actually fulfill the
design aim of weighted fairness, and can provide the differentiation service
in the WLAN.
Keywords: Weighted Fairness, Quality of Service, IEEE 802.11 DCF,
Multiple Classes, Performance Analysis.
Title
of the Paper: The
Perspectives of the Amateur University Networks – AMUNETs (Part 2)
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Authors:
Miroslav Skoric
Abstract: This paper discusses results of the recent experiments, which
intention was to test security in accessing e-mail servers and radio relay
systems within the amateur radio digital infrastructure. There are many
opportunities in available safety measures, which support the integrity of
user's and system administrator's credentials. This work suggests various
methods which aim is to bridge the gap between the improved safety and
comfort in regular end user's and system administrator's activities within an
amateur radio computer network.
Keywords: amateur radio, AMUNET, communication, computer, security,
privacy, university, education
Title
of the Paper: Spectrum Emission Mask for Coexistence between Future WiMAX
and Existing Fixed Wireless Access Systems
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Authors:
Zaid A. Shamsan, Lway Faisal, S. K. Syed-Yusof, Tharek Abd. Rahman
Abstract: This paper introduces a new coexistence study of the future WiMAX
system and existing fixed wireless access (FWA) systems and investigates its
feasibility. Spectrum emission mask as an interference mitigation technique
is used as well as interference to noise ratio (I/N) of -6 dB as one of
standard sharing criterion value at FWA systems recommended by international
telecommunication union radio sector ITU-R. Three channel bandwidths of (3.5,
7, and 10 MHz) of WiMAX system in the band 3500 MHz are selected to be
studied with 7 MHz FWA channel in dense urban area. All parameters of the two
systems are presented and methodology is explained. It is well known that
frequency distance rules are an important of frequency coordination process
in most radio services, so frequency and distance separations are determined
and analyzed for both terms co-channel interference and adjacent channel
interference in the different interference scenarios which are supposed. This
coexistence and spectrum sharing study is considered as an initial step
toward beyond 3G or IMT-Advanced coexistence with FWA systems.
Keywords: Coexistence, Sharing, WiMAX systems, Fixed wireless access
systems, Interference-to-noise ratio, Spectrum emission mask.
Title
of the Paper: Potential Penalty Distance between FSS Receiver and FWA for
Malaysia
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Authors:
Zaid A. Shamsan, Lway Faisal, S. K. Syed-Yusof, Tharek Abd. Rahman
Abstract: This paper deals with the Interference between Fixed Satellite
Service Earth Station (FSS-ES) receiver and Fixed Wireless Access (FWA) in
term of possible separation distance, for Malaysian environment. The study
began with detailed clarification of worldwide regulatory and C-Band user
history. Subsequently, detailed calculations of the current and most useful
formulas for path loss effect and clutter loss by using the existing
parameters of both services had been done. Thereafter, FSS axis receiving
gain and radiation pattern covered in term of maximum possible separation
reduction. Moreover, Site shielding, isolation, off-Axis, In-Band and out of
band have been discussed in several scenarios. Calculations, analysis and
simulation have been done by using Matlab software. Extracted conclusions
highlighted the subsistent situation and proposals for future work.
Keywords: Interference, FSS, FWA, Malaysia, LNB and Saturation.
Title
of the Paper: A new High-Speed Interconnect Crosstalk Fault Model and
Compression for Test Space
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Authors:
Shang Yuling, Li Yushan
Abstract: Signal integrity of high-speed interconnects has significant adverse
effect on the proper function and performance of VLSI. A new crosstalk fault
model is presented for testing glitch and delay in this paper. This model
takes odd and even mode transmission into account based on parasitic RLC
elements of interconnect. It can stimulate the maximal signal integrity loss
compared to maximal aggressor (MA) model and maximal dominant signal
integrity (MDSI) model. Then a compression algorithm for test space is
proposed. Several properties such as symmetry, decay and superimposition are
studied. Compression steps are explained in detail. Finally simulation is
performed and experimental results show that this model is more effective
than MA and MDSI models.
Keywords: crosstalk, compression algorithm, fault model, high-speed interconnect
Title
of the Paper: Effect of TCP and UDP Parameters on the Quality of Video
Streaming Delivery
over
the Internet
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Authors:
Mazhar B. Tayel, Ashraf A. Taha
Abstract: Delivering real-time video over the Internet is an important issue
for many Internet multimedia applications. Transmission of real-time video
has bandwidth, delay, and loss requirements. The application-level quality
for video streaming relies on continuous playback, which means that neither
buffer underflow nor buffer overflow should occur. Since the Best Effort
network such as the Internet does not provide any Quality of Service (QoS)
guarantees to video transmission over the Internet. Thus, mapping the
application-level QoS requirements into network-level requirements, namely,
limited delay jitters. End-to-end application level QoS has to be achieved
through adaptation. Since the QoS of video streams over IP networks depends
on several factors such as video transmission rate, packet loss rate, and
end-to-end transmission delay. The objectives of this paper are to simulate
an adaptation scheme to include the effect of User Datagram Protocol (UDP)
parameters on delay jitter and datagram loss values to increase the
efficiency of UDP protocol to prevent the network congestion and increase the
adaptivity and also, simulate an adaptation scheme to include the effect of
Transmission Control Protocol (TCP) parameters on the transmission rates to
increase the adaptivity of the transmission.
Keywords: Quality of Service, Video streaming, Internet, TCP Window,
UDP, Iperf.
Title
of the Paper: Multicast Survivability in Hierarchical Broadcast Networks
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Authors:
Azad Azadmanesh, Axel Krings, Daryush Laqab
Abstract: Despite the increasing number of applications that benefit from
multicasting, most reliable multicast protocols consider omission faults
only. This research is concerned with survivability of multicast
communication where the communication medium is shared among the hosts. The
approach presented specifies that a network with N nodes is resistant against
network omissions and malicious nodes if N >= 2t + b + 2, where t and b
are the number of malicious and benign faulty hosts, respectively. The
simulation results show that the network traffic is dynamically adapted to
the rate of faults and that the network performs well under omission and
malicious faults, unless the rate of faults is high. Furthermore, it is shown
that each additional network segment requires (2tg + 1) gateways, where tg
indicates the number of faulty gateways.
Keywords: Byzantine agreement, Hybrid fault models, Multicast,
Peer-to-Peer networks, Ad-hoc networks
Title
of the Paper: Record Path Header for Triangle Routing Attacks in IPv6
Networks
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Authors:
Su-Kit Tang, Kin-Yeung Wong, Kai-Hau Yeung
Abstract: Triangle routing is one of the serious attacks to the Internet
infrastructure. It can be caused by malicious routers which misroute packets
to wrong directions. This kind of attacks creates network problems such as
network congestion, denial of service and network partition and results in
degrade of network performance. This paper gives a comprehensive study on how
the path analysis combats the triangle routing attacks. We discuss the
method, implementation and limitation of path analysis to detect triangle
routing in IPv4 network. We also discuss the implementation of path analysis
in IPv6 by proposing a new extension header, called Record Path Header.
Keywords: IPv6,
Infrastructure, Routing, Attack
Issue 7, Volume 7, July 2008
Title
of the Paper: A Unified Approach for Heterogeneity and Node Fault
Robustness in Dynamic Sensor Networks
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Authors:
Simone Gabriele, Paolo Di Giamberardino
Abstract: The paper deals with the area coverage problem for a network of
mobile sensors. Continuous mobility is used for getting measures over the
area of interest with a reduced number of sensors units that do not cover all
the area at any time but, moving, assure the measure at any point within a
prefixed time interval. In addition, the case of heterogeneous network is
addressed, in the sense that each node can be equipped with a different set
of sensors. A centralized formulation of the control problem for the motion
of the agents is given. It is also shown that the same problem formulation
can be used to address the problem of nodes faults robust coverage for over
dimensioned networks. Constraints introduced by the actuator limits as,
communication connection and collision avoidance are clearly considered. A
global solution is proposed and some simulations are reported to show its
effectiveness.
Keywords: Sensor network, dynamic configuration, optimal motion,
network communications, heterogeneous sensors, robust coverage.
Title
of the Paper: Improving the Reliability of Ad-hoc on Demand Distance
Vector Protocol
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Authors:
Houssein Hallani,
Seyed A. Shahrestani
Abstract: Ad-hoc networks are a collection of mobile nodes that can be
deployed without the need for any centralized management infrastructure. As
such, the very basic operation of these networks is dependent on the
cooperation of their nodes to provide communication routes. Furthermore, such
networks are prone to several security risks. Consequently, when some nodes
behave maliciously or in a selfish manner, the operation of the whole network
can be severely affected. The behavior of such nodes can result in
degradation of the performance of the network or even disruption of its
operation altogether. This work reports the results of studying the Ad-hoc
network performance in the presence of malicious nodes. It also proposes an
approach that takes the behaviour history of member nodes into account, to
improve network reliability. The reported approach, namely Behavior Ad-hoc On
Demand Distance Vector approach, is based on discovery of communication paths
with minimal number of selfish or malicious nodes. Using OPNET simulator,
several situations of practical significance have been studied and analyzed. The
results of these studies show that by applying the proposed approach, marked
improvements in the performance and reliability of the Ad-hoc networks depend
on AODV protocol can be achieved.
Keywords: Ad-hoc networks, AODV, Behavior analysis, Malicious node,
Selfish node.
Title
of the Paper: Real Time Monitoring in Web Telerobotics
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Authors:
Ionut Resceanu, Marius Niculescu, Cristina Pana
Abstract: There is a growing need for humans to perform complex remote
operations and to extend the intelligence and experience of experts to
distant applications. A blending of human intelligence, modern information
technology, remote control, and intelligent autonomous systems is required. Telerobotics
goes beyond autonomous control in that it blends in human intelligence and
action as appropriate. It goes beyond teleoperation in that it incorporates
as much autonomy as is possible or reasonable. A new approach for solving one
of the fundamental problems facing teleautonomous systems is discussed: the
need to overcome time delays due to telemetry and signal propagation. Optimized
maintenance can reduce operating costs by demanding less resources and
avoiding equipment breakdown, hence ensuring that daily manufacturing and
production will not be interrupted. Web-based maintenance is one of the most
efficient methods for optimizing maintenance. The Web-based monitoring system
discussed provides remote sensing, monitoring, and on-line fault diagnosis
for equipment, together with a collaborative maintenance platform for
international experts to interactively share their experiences in
maintenance.
Keywords: Telerobotics, Web, Internet, Control, TCP/IP, UDP,
Real-Time, Monitoring
Title
of the Paper: OFDM System under the Combined Effect Analysis of the Phase
Noise, Carrier Frequency Offset, Doppler Spread, and Amplifier Nonlinearity
of the SEL
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Authors:
Mohammad Mahmoud, Mona Raid
Abstract: In this paper, we provide an exact closed-form expression of the
effective signal-to-noise ratio (SNR) for orthogonal frequency division
multiplexing (OFDM) performance under the combined effect of the phase noise,
frequency offset, and amplifier nonlinearities of the soft envelope limiter
(SEL). A simplified approximate expression is also obtained for the effective
SNR under certain conditions. This formula describes explicitly the various
parameters with the system performance. After deriving the effective SNR, we
evaluate the bit-error-rate (BER) for slowly fading Rayleigh channel for QPSK
and 16-QAM modulation formats. We also obtain the minimum total degradation
(TD) versus phase noise rate for different values of frequency offset rate as
a criterion of performance evaluation. We show that the degradation is
increased as the phase noise levels and frequency offset levels are
increased. For 16-QAM modulation format, we have obtained even worse results
compared with QPSK modulation format.
Keywords: OFDM, Phase Noise, CFO, Doppler Spread, and Nonlinear
Amplifier.
Title
of the Paper: Performance of Partial Parallel Interference Cancellation
With MCCDMA Transmission Techniques for Power Line Communication Systems
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Authors:
Yung-Fa Huang, Tan-Hsu Tan, Chia-Hsin Cheng, Neng-Chung Wang
Abstract: In this paper, we describe and evaluate multistage partial parallel
interference cancellation (PPIC) multiuser detectors to improve the
performance of multi-carrier direct-sequence code-division multiple-access
(MC-CDMA) power line communication (PLC) systems over frequency selective
fading channels with nonperfect power control. To improve the effectiveness
of PPIC, we examined the adequate partial cancellation weights (PCWs) for the
PPIC. Thus, the performance improvement in MC-CDMA based PLC systems using
PPIC multiuser detectors is investigated. The high data rate demanded in the
multimedia PLC systems can be offered by the MC-CDMA systems. However, the
multiple access interferences (MAIs) exist in the frequency selective fading
channels for the down link even though using an orthogonal pseudo-random
noise (PN) code and occur for the up link due to the non-orthogonal spreading
codes. In the high system load, the MAIs become the dominant factor degrading
the performance. Therefore, the performance of a multistage PPIC is further
investigated for the MC-CDMA PLC systems. Simulation results show that with
adequate cancellation weights, the PPIC scheme can obtain a superior
performance than the conventional PIC scheme, especially at heavy system
load. Furthermore, with the bit-error rate (BER) requirements of 0.001, the
five-stage PPIC with PCWs, 0.7, 0.8, 0.9 and 1 for stage 2, 3, 4 and 5,
respectively, increases the capacity from 15 of CPIC to 19 users with the
processing gain 32 over the power line channels.
Keywords: MC-CDMA, PLC, Multiuser detection, Multiple access
interference, Partial parallel interference cancellation, Partial
cancellation weight
Title
of the Paper: Efficient Mobile Communication Solutions for Remote Data
Acquisition, Supervisory and Control Systems
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Authors:
Mariana Jurian, Ioan Lita, Daniel Alexandru Visan
Abstract: Wireless technologies (mobile communications or other
radiofrequency transmission methods) represent reliable and efficient
solutions for remote data acquisition, supervisory and control systems. The
correct selection of the proper transmission method from the wide variety of
radio transmission methods and standards represents an important issue. For
this reason in the firs part of this paper are presented briefly, the newest
and most efficient wireless technologies suitable for remote data
acquisition, supervisory and control systems. After that, the paper is focus
on the GPRS method as solution for implementing such distributed systems. Are
presented in detail the GM862 GSM/GPRS modules and the development boards
used for tests. In the last part of the paper are listed few basic AT command
that shows the operation of presented modules.
Keywords: mobile communications, wireless sensor network, Bluetooth,
General Packet Radio Service, transmission distance, power consumption.
Title
of the Paper: Redundancy versus Video and Audio Human Perception
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Authors:
Michael Bank
Abstract: A proposal is put forward for an possible explanation of human
perception algorithm. The main conclusion of different kinds of art
perception examination is necessity of big part of signal redundancy. The
article illustrates the meaning of redundancy versus human perception. It
turned out, that there are common methods of redundancy creation in different
kinds of art like painting, architecture, music and speech.
Keywords: Painting, music, speech, perception, redundancy, Autism
Title
of the Paper: Viability of ISI-Based TETRA over Satellite
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Authors:
Roman Novak
Abstract: Satellite communications, by its very nature of providing wide-area
coverage, can play an important role in interconnecting TETRA networks. A
satellite link may be used to support any of the interfaces in TETRA network.
However, the selection of particular interface applies to specific scenarios
and provides different advantages and disadvantages. The viability of a
satellite link for the interconnection of two TETRA networks using the
Inter-System Interface (ISI) is studied with respect to desired functionality
and QoS. ISI-based TETRA over satellite can be used in emergency situations
when no terrestrial infrastructure exists between the two networks, as well
as in normal operations as an alternative to ground based interconnection
infrastructure. The response time of different services in a given network architecture
is of primary concern because large propagation delay is the main source of
service degradation. A modified version of critical path analysis, as it
applies to protocols, is used to estimate total propagation delays for a set
of ISI services. The appealing property of the critical path length is that
it gives an accurate estimate of total propagation delay for a given service
and thus represents a quantitative measure of QoS degradation as experienced
by the end user. The results presented show larger degradations of QoS for
the group call scenarios. The most disturbed are acknowledged group call
setup and group call maintenance. A Performance Enhancing Proxy (PEP) is
proposed to improve the performance of the TETRA services over the ISI if
satellite links are involved.
Keywords: TETRA, satellites, Inter-System Interface, propagation
delay, critical path, QoS
Title
of the Paper: The Benefits of PKI Application and Competitive Advantage
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Authors:
Chi-I Hsu, Yu-Ching Tung
Abstract: To understand the implementation advantages of Public Key
Infrastructure (PKI) applications, this study identified PKI benefits and
examined the effect of PKI benefits on competitive advantage. Four aspects of
benefits are identified including cost benefits, time benefits, security
benefits, and profit benefits. The CFA and regression analysis are used to
check the factor structure and test the hypothetical relationships. The
results suggest that the PKI benefits on saving cost, increasing security,
and making profit have significant effect on obtaining the competitive
advantage of corporate. A market survey is also reported to reveal the status
of PKI applications in Taiwan.
Keywords: Public Key Infrastructure, PKI Benefits, Security,
Competitive Advantage
Title
of the Paper: Developing Virtual Simulation Game for Authentic Learning:
Realizing Partnership between University and Industry
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Authors:
Andreja Istenic Starcic
Abstract: The paper describes the development of virtual
simulation-game-based learning environment. The key objective is to offer
students and lifelong learners simulation-game environment that preserves
real life authenticity. Presented is a simulation-game tailored for
diversified student groups in graduate courses and employees in the tourism
sector, aiming at giving them competences for international and global
business management. The constructivism theory provides the framework of the
simulation-game pedagogical approaches: learning by doing, learning with live
experiences, experiential learning, problem-based learning, and learning in
safety. The paper presents the partnership between university and industry in
the design process of simulation-game and virtual community for assisting
collaboration among users: entrepreneurs, students, teachers and trainers. Focus
groups were formed in the design process of simulation-game, engaging all
relevant stakeholders, and needs assessment was performed at the beginning of
the project.
Keywords: Virtual simulation game, Constructivism, Virtual community,
Lifelong learning, Business simulation, Hephaistos simulation software,
Higher education, Wiki
Issue 8, Volume 7, August 2008
Title
of the Paper: Subspace-based Blind Multi-user Detection for TH-UWB Systems
in Multi-path Channels
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Authors:
Chia-Hsin Cheng, Wen-Jun Lin,
Kai-Jie Chen
Abstract: A subspace-based blind adaptive linear minimum mean square
error (MMSE) detector has been proposed for multi-user detection in a direct
sequence code-division multiple-access (CDMA) system even when multi-path
channels are unknown. In this paper, the applicability of the subspace-based
blind adaptive algorithm in multiple access ultra-wideband (UWB) systems is
investigated. The problem of blind demodulation of multi-user information
symbols in a high-rate UWB network in the presence of both multiple access
interference (MAI) and inter-symbol interference (ISI) is also considered. Moreover,
the Rake receiver is adopted to collect multi-path gains. The performance of
the subspace-based blind techniques is shown under time-variant UWB
multi-path channels.
Keywords: Ultra-wideband, Blind adaptation, Multi-user detection,
Subspace tracking.
Title of
the Paper: Numerical and Experimental Analysis of Electromagnetic Field in
a Probe Coupled Cylindrical Metallic Cavity
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Authors:
Jugoslav Jokovic, Bratislav Milovanovic, Nebojsa Doncov
Abstract: The procedure for analysis of electromagnetic field in a
cylindrical metallic cavity, based on
reflection and transmission characteristic, is presented in the paper. An
analysis of procedure efficiency to resonant modes identification is
conducted numerically and experimentally verified. As a numerical tool, TLM
time-domain method, enhanced with the compact wire model to account for the
presence of feed and monitoring probes, is used. Conditions, in terms of
probe dimension, for achieving the best source matching and optimum coupling
between ports, are considered. Results obtained using reflection and
transmission procedures are also compared, in terms of modes identification
and resonant frequency dependence of probe dimensions.
Keywords: Cavity, Wire, Probe, TLM Time-Domain Method, Reflection,
Transmission
Title
of the Paper: Fusion of Technology in Analysis, Design and Comparison of
Numerical Techniques for Rectangular Microstrip Patch Antenna
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Authors:
S.
Raghavan, T.
Shanmuganantham
Abstract: In today’s scenario higher integration and smaller layout
size are the two major trends in RF and Microwave industry, lead to more
prominent role in electromagnetic high order effects. Recent years the
important in the development of numerical techniques has been the versatility
of the method. In this paper, we have present the various numerical techniques
to compute such effects in Microwave Integrated Circuit based designs,
highlighting their specific features with comparison of numerical techniques
for design of rectangular Microstrip Patch Antenna. Here we are compared few
numerical techniques, in this Finite Element Method is a more powerful and
versatile, more storage requirement, less CPU time. Numerical
characterizations and modelings of guided wave passive components have been
an important research topic in the recent years. This is due to increased
research and development in millimeter-wave integrated circuits and
monolithic integrated circuits. Another aspect important in the development
of numerical techniques has been the versatility of the
method. Higher integration and smaller layout size, two major trends in
today’s RF/microwave industry, lead to more prominent electromagnetic high
order effects. In this paper, the authors present a survey of existing
Numerical techniques to compute such effects in microwave integrated
circuits, highlighting their specific advantages/disadvantages and comparison
for a circuit designers and simulation results also compared.
Keywords: Microwave Integrated Circuits, Numerical Techniques,
Artificial Neural Networks.
Title
of the Paper: Network Design and Optimization for Quality of Services in
Wireless Local Area Networks using Multi-Objective Approach
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Authors:
Chutima Prommak, Naruemon Wattanapongsakorn
Abstract: A multi-objective wireless local area network (WLAN) design
models have been developed to optimize the network quality of services. The
proposed model combines three problems together, including the optimal access
point placement, the frequency channel assignment and the power level
assignment. In addition, it accounts for user population density in the
service area, traffic demand characteristics and the physical structure of
the service area. The design model aims to determine a network configuration
that optimizes the network quality of services in term of the radio signal
coverage and the data rate capacity to serve expected user traffic demand in
the service area. Numerical results and sensitivity analysis is performed to
analyze the improvement of the network performance. We found that when we
incorporate the issue of the user data rate capacity in the design model, we
can greatly improve the quality of service in term of data rate requirement
while slightly degrading the signal coverage availability. It is observed
that as the weight factor of the user data rate capacity objective increases
from 0 to 1, the user satisfaction level increases about 40% while the signal
coverage availability decreases about 10%.
Keywords: Multi-objective, Optimization, Network design, Wireless
Local Area Networks.
Title
of the Paper: Optimal Cluster Number Selection in Ad-hoc Wireless Sensor
Networks
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Authors:
Tung-Jung Chan, Ching-Mu Chen, Yung-Fa Huang, Jen-Yung Lin, Tair-Rong Chen
Abstract: In clustering-based wireless sensor networks (WSNs), a
certain sensing area is divided into many sub-areas. Cluster formation and
cluster head selection are well done in the setup phase. With the
predetermined probability and random, every round in the WSNs has the
different cluster numbers and cluster heads. However, the well known
technique in cluster-based WSN is especially the low energy adaptive cluster
hierarchy (LEACH) and its energy performance is improved due to the scheme of
clustering, probability, and random. The clustering-based WSN has sensor
nodes organized themselves with the pre-determined variable p to form
clusters. With the pre-determined p variable and probability, every round has
different cluster numbers which are not the optimal solution. Therefore, in
order to evenly consume nodes’ energy, this paper proposes a fixed optimal
cluster (FOC) numbers that is to analyze the entire network first to have the
optimal cluster numbers and then apply it to form the optimal cluster
numbers. Moreover, there are two different types of the
optimal cluster numbers depending on the location of the base station. One is
that the base station is setup at the center of the sensing area. The other
is that the base station is setup at the far way of the sensing area. Finally,
by the optimization analysis of cluster numbers applied to the ad-hoc WSN
before sensor nodes are randomly deployed, the simulation results show the
entire network lifetime can be extended very well.
Keywords: Ad-hoc Wireless sensor networks, Analysis, Optimal Cluster
numbers, Energy efficiency,
Clustering-based, Pre-determined variable, Random, Base station location.
Title
of the Paper: A Non_Ack Routing Protocol in Ad-hoc Wireless Sensor
Networks
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Authors:
Ching-Mu Chen, Tung-Jung Chan, Tair-Rong Chen
Abstract: A wireless sensor network contains many sensor nodes in a certain
sensing area. Every sensor node consists of a central processing unit,
transmitting unit, receiving unit and power supply unit. In order to have
efficient sensed messages, both the base station and sensor nodes have to
communicate for each others as well. Therefore, a certain sensing area is
divided into many sub-areas and every sensor node transmits its message to
cluster head which, normally, will integrate and forward these messages to
the base station. At the first step, set-up phase is applied to form clusters
and to select cluster heads. During the second phase, the transmission phase,
every sensor node received a message from another node has to transmit a
confirmed message, acknowledgement (ACK), to ensure whether or not the data
has been received which means every sensor node will dissipate much energy on
transmitting and receiving. However, this paper proposes an adaptive routing
protocol called Non_Ack in the Ad-hoc wireless sensor networks that is the
data for every sensor node is transmitted directly to the cluster head and
then forwards back to the base station. Some conditions for these sensor
nodes with the sensed data directly transmitted without any acknowledgement
may be failed so that this paper also considers as nodes fail to transmit the
data back, the base station will be taken over for the network. By the
consideration of these failure nodes, the base station will establish a
binary tree for fault tolerance. A binary tree in the base station is also a
big help for query-based routing protocol. Finally, simulation results reveal
the entire network lifetime can be extended well and the performance is much
better.
Keywords: Energy efficiency, Network lifetime, Ad-hoc wireless sensor
networks, Routing protocol, No acknowledgement, Binary tree, Query-based.
Title
of the Paper: A Study of Propagation Effects in a Wireless Test Bed
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Authors:
Albert A. Lysko, David L. Johnson
Abstract: The paper discusses several effects influencing the
propagation in a laboratory wireless test bed, and also aspects important for
designing and setting up the wireless test bed with space constraints. A
numerical electromagnetic model for the full scale 7×7 wireless mesh network
test-bed is discussed. The model includes the coupling and diffraction
effects, and is based on the method of moments. The results of numerical
simulations are validated with microwave, antenna and received signal
strength (RSSI) measurements. The methodology developed for the Wi-Fi card
based measurements and relying on the RSSI values is also discussed. The
findings from the simulations help to quantify errors and provide grounds for
suggestions towards improving design of test-beds.
Keywords: electromagnetic propagation, wireless mesh network, wireless
sensor network, wireless test-bed, wireless laboratory.
Title
of the Paper: The Laser Satellites Communications and Laser Noises
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Authors:
Marketa Mazalkova
Abstract: The gain of advanced optical communication systems is
reduced by the noise of optical source. Coherent optical communication
systems are in particular very sensitive to the noise transmitter and local
laser. Optical space communications is on the verge of being reality. The
paper involves the introduction into laser satellite communication system. The
paper includes briefly analysis, optimization, design and system level
development of signal transferring between satellites. Research opportunities
in this area include development of laser beam acquisition, tracking and
pointing techniques and algorithms, development of computer aided analysis
link budget for the free space channel, systems engineering (analysis and
design) of optical transmission development of high efficiency flight
qualifiable solid-state lasers, fast fine-pointing mirrors high update-rate
acquisition and tracking cameras and very low-noise high-quantum efficiency
receiver. It is focused
on the noises’ limits of the optical communication system. The paper solves
the problems with noises’ limits by various ways. There are mentioned the
optical energy output on an aperture’s spread of optical detector and
incoherent detection of optical carrier wave.
Keywords: laser, satellite systems, laser communication, space
channel, noise limits, optical communication, range loss, signal transfer
loss, satellite communications
Title
of the Paper: Cellular / Wireless LAN Repeater System by Wireless Optical
Link with Optical Power Supply
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Authors:
Nobuo Nakajima, Naohiro Yokota
Abstract: Wireless market, such as cellular systems and wireless LAN,
becomes huge and is still expanding. Since operational frequency and
transmission bit rate are increasing, much more base stations or access
points are necessary to overcome capacity and link budget problems. Most of
the places suitable for the base station were already occupied by the
existing systems. In the future, sometimes, new base station must be
installed at the places where power supply or transmission cable is not
available. The proposed repeater system is applicable for such case. The RF
signals are fed to the repeater through the air by optical beams. And
electrical power is fed by the optical beam, too. This paper describes the
design principle and experimental results of the proposed system.
For example, by using 26cm diameter optical beam for power transmission,
available forward link RF power at the repeater station is 10mW in the case that
the distance between the base station and the repeater station is 40 m.
If a diameter of the optical beam for power transmission is 48 cm,
100 mW RF output power is available for a forward link. Since micro cell
structure will become majority in the future high frequency and high bit rate
cellular and wireless LAN systems, these amount of RF output power may be
enough for many cases.
Keywords: RoF, Wireless, Optical Transmission, Optical Power
Transmission, Cellular System
Title
of the Paper: An IPSec-Based Key Management Algorithm for Mobile IP
Networks
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Authors:
Neng-Chung Wang, Jong-Shin Chen, Yung-Fa Huang, Tzu-Wei Chan
Abstract: The Mobile IP network environment for users is very
vulnerable to malicious attacks, such as denial-of-service,
man-in-the-middle, and other types of attacks. For protection, the IETF
standard Mobile IP protocol is modified with IP security (IPSec) primitives,
which control the packet flow from a mobile host through multiple security
gateways. In addition, IPSec uses strong cryptographic authentication and
encryption algorithms to protect the integrity and confidentiality of IP
traffic. In this paper, we proposed a key management algorithm for Mobile IP
networks based on IPSec. The proposed scheme includes two parts: a wired
network and a wireless network. In the wired network part, the proposed
scheme produce two keys in each security gateway, transfers a packet with an
encrypted key and receives a packet with a decrypted key. In the wireless
network part, we use AH to arrive at wireless segment packet security. By the
proposed scheme, we can enhance the security of Mobile IP networks.
Keywords: Key management, IPSec, Mobile IP, Network security, Private
key, Public key.
Issue 9, Volume 7, September 2008
Title of the Paper: On the Power Consumption of 802.16e Listening
State
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Authors:
Jia-Sheng R. Chen , Hsing Mei, Yuan-Chang Chang
Abstract: Energy consumption strategy is crucial to the future of Broadband
Wireless Access (BWA). In order to manage limited battery power efficiently,
the IEEE 802.16e standard defines the sleep mode operation in its MAC
protocol to maximize the lifetime of Mobile Station (MS) and to enhance the
network capability. In this paper, we analytically investigate the power
consumption of listening state and sleep state operations of IEEE 802.16e. A
Mobile Station goes to sleep mode when there is no data to send or receive
with the Base station (BS). After a Mobile Station stays in sleep state for a
pre-defined time, it wakes up and transits to listening state periodically to
check if the Base Station has any buffered downlink traffic destined to the
Mobile Station itself. Although the listening interval is shorter than sleep
interval, the power consumption should consider both listening state and
sleep state operations. Our proposed model and numerical results prove the
listening state may consume up to 90% of the total power consumption in some
case.
Keywords: WiMAX, Power consumption, Listening state, Sleep mode,
802.16e.
Title
of the Paper: Ad-hoc
on Demand Distance Vector (AODV) Performance
Enhancement with Active Route Time-Out parameter
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Authors:
Wadhah Al-Mandhari, Koichi Gyoda, Nobuo Nakajima
Abstract: The routing protocols play an important role in the performance of
the Ad-hoc mobile networks. The Ad-hoc On-Demand Distance Vector Routing
Protocol (AODV) is a reactive routing protocol for mobile networks. The route
discovery process in AODV is initiated only prior to link establishment for
data communication. This research focuses on the effect of the Route states
hold time parameter on the performance of the Ad-hoc mobile network which is
indicated by the Packet Delivery Rate (PDR). Our aim is to identify the
effect of varying Route states hold time parameters for Ad-hoc On Demand
Distance Vector (AODV) and measure the degree at which the number of stations
and their movement speeds affects the PDR. These factors are presented,
discussed and simulated using OPNET simulation software.
Keywords: Aodv, Opnet, Olsr, Rreq, Rrep, Active route timeout (ART),
Packet delivery rate (PDR)
Title
of the Paper: Gain and Pattern Improvements of Array Antenna using MSA
with Asymmetric T-shaped Slit Loads
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Authors:
S. Kampeephat, P. Krachodnok, M. Uthansakul, R.
Wongsan
Abstract: This paper presents a 1×4 array antenna using asymmetric T-shaped
slit loaded microstrip antenna (MSA). The antenna consists of four MSAs align
vertically on a dielectric substrate and ground plane. This antenna will be
utilized in WLAN applications as the commercial panel antenna. A modified
array configuration is proposed to further enhance the antenna radiation
characteristics and usable bandwidth. The desired patterns of array are
improved by adjusting the array element spacing from λ/2 down to
λ/3.
Moreover, alternating of the slit loads positions on each side of some patches
in array can control the directive patterns to be symmetric shapes. The
measured results of the radiation pattern, input impedance, return loss,
VSWR, directive gain, and are also conducted for verification of the
IE3D-based simulated results. With good agreement between the simulated and
measured results and accordance of the requirements, therefore, this proposed
panel antenna is appropriate for the wireless applications.
Keywords: Array Antenna, Directive Gain, Microstrip Antenna, Radiation
Patterns, Slit Load
Title
of the Paper: Implementation of the
Communication
System for
Clubfoot
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Authors:
Smaranda Cosma, Dan Cosma, Adina Negrusa , Madalina Valeanu , Grigor
Moldovan , Dana Vasilescu
Abstract: In view of finding out the size of and demand created by clubfoot
in our country, we have designed, created and implemented an integrated
communication system for the congenital idiopathic clubfoot. On the basis of
the information and data in this system, the parents have an information
resource at their disposal that enables them reach a decision concerning the
way in which the deformity of their child could be treated. The integrated
informational system for the congenital clubfoot has two components: the
medical component – dedicated to the medical staff – and the informative
component – dedicated to the parents and children suffering of clubfoot. The
system also, will generate positive economical implications.
Keywords: National Register, clubfoot, medical communication,
database, research
Title
of the Paper: Design and Performance Evaluation of an Indoor Ranging
System Using Audio Chirp and MUSIC Algorithms
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Authors:
Hamid Farrokhi
Abstract: In most existing indoor acoustic ranging systems, a range is
estimated based on measuring the TOA of an ultrasonic wave. Due to high
directivity of ultrasonic transducers and high attenuation of ultrasonic
waves with distance in air, these systems cannot provide a range in large
indoor environments. To achieve longer ranges, a TOA-based acoustic ranging
system that uses a low frequency audible signal is proposed. The audible
sound is a spread spectrum LFM signal, which is generated with a standard
speaker and received with a standard microphone. The indoor acoustic
environment is modeled with a multipath propagation channel whose
characteristics are different from those of outdoor environments. It is shown
that the classical ranging techniques used in traditional systems, such as
the GPS, Sonar, Radar, etc., may not provide the optimum performance in
indoor environments. The complexity and site-specific nature of indoor
acoustic propagation, when using traditional correlation techniques, often
lead to the creation of undetectable direct-line-of-sight situations. It is
shown in this paper that by using MUSIC super-resolution techniques, namely
the root-MUSIC, which is applied to the estimated frequency response of the
multipath indoor propagation channels, the substantial TOA errors can be
reduced significantly and the range accuracy improved by a factor of at least
3.
Keywords: KEYWORDS
Title
of the Paper: Scalable and High-Precision Function-Approximated Images and
Its Secure Coding
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Authors:
Yasuhiro Omiya, Mitsuteru Nakamura, Kazuki Katagishi, Yasuo Morooka, Kazuo
Toraichi, Hitomi Murakami
Abstract: Function-approximated images are suitable for transmission over the
networks, because they can be scaled on the sidelines of various resolutions
of network terminals with relatively small amount of information. In this
work, we use the Fluency function-approximation method that utilizes the
Fluency information theory. The theory can deal with images in scalable and
high-precision. Transmitted images may contain critical information that must
be protected from malicious information tapping. The security, however,
depends on the implementations of lower layers of the network protocol stack
that are not available in many circumstances. In this paper, we propose a new
image description format that applies security to functionapproximation
coding. It utilizes the structured properties of function-approximation
format to enhance its security by hiding the coordinates of components of
images. The proposed method is a secure mechanism for image coding itself;
therefore, it enables secure transmission of function-approximated images
without requiring any secure protocols in the lower layers. Furthermore,
being independent from the lower layers, it enables flexible combinations of
security mechanisms to enhance the security.
Keywords: Function-approximation, Security, Image coding, Fluency
information theory.
Title
of the Paper: Telemetry Data Transmission, Storage and Processing System
Supporting Ski-mountaineering Race
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Authors:
Oldrich Horak
Abstract: The article describes design of a new telemetry data transmission,
storage and processing system used to transmit, store and process data
measured during an overnight ski-mountaineering race. The proposed system has
to solve many problems connected to the data transmission in the
hard-accessible terrain, transmitted data storage and processing and some
more problems originated from specific conditions of such a race. Special
emphasis is given on the low-budget multi-platform solution and easily
accessible technologies.
Keywords: Telemetry, Transmission, Storage, Processing, Network,
Hard-accessible terrain, Agent, Multi-platform
Title
of the Paper: Inter-cell Interference for Reverse Link in WCDMA
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Authors:
Laura Garcia-Lopez, Mario Reyes-Ayala, Sergio Vidal-Beltran
Abstract: In this paper, the WCDMA inter-cell interference is carried-out for
both, soft and hard handovers. The main parameters used to evaluate the
proposed model were the other-cell interference factor and the outage
probability. The results of this work allow us to compare any sort of frequency
reuse schemes in this spreadspectrum multiple access technique.
Keywords: soft HO, hard HO, frequency reuse scheme, fading, inter-cell
interference, WCDMA.
Title
of the Paper: Optimization of Application QoS Protocols for 3G/4G Mobile
Networks
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Authors:
Gordana Gardasevic, Milojko Jevtovic, Philip Constantinou
Abstract: The importance of Quality of Service (QoS) provisioning has become
one of the central issues of 3G/4G mobile network design and analysis. Mobile
multimedia applications have high demands in terms of available network
resources, equipment design and QoS performances. The variety of new
applications (TV program distribution, tele-engineering, high definition
video telephony, medical applications, location-based services, etc.)
deployed in modern mobile networks implies the necessity for precise and
consistent analysis. Most of the research activities in this field have been
oriented to the areas of system, network, transport and middleware support
for QoS. On the other side, there is a lack of proposed architectures and
protocols for implementing an overall adaptive application QoS support. The
challenging task for research activities is the creation of an adaptive
application QoS protocol suit in order to obtain optimal QoS performance. The
selection of the appropriate metrics for performance evaluation represents an
important step for establishing the application QoS profile. In this paper we
identify key adaptation issues and propose the architectural framework for
application level QoS adaptation.
Keywords: Mobile Networks, Quality of Service, Application, Protocols,
Performance evaluation, Optimization .
Issue 10, Volume 7, October 2008
Title of the Paper: Control of Multimedia Wireless Communication
Network
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Authors:
Marius-Cristian Niculescu, Ionut Resceanu
Abstract: - This paper presents a new management technique aimed at
increasing the energy efficiency of client-server multimedia applications
running on wireless portable devices. Multimedia communication can be defied
as the field pertaining to the formation, storage, retrieval, dissemination
and usages of multiple “media” such as images, texts, graphics, animation,
video and audio. The recent explosive growths of the Internet and multimedia
research have raised the interest in distributed multimedia systems over
Internet. In this paper, we propose an architecture for capturing,
distributing and displaying multimedia content through existing Internet and
Intranet infrastructures. An objectoriented architecture for the building of
customized multimedia clients and servers facilitates software maintenances
and updates as application requirements evolve and code reuse. The
architecture is consisted of client/ server model.
Key-Words: - WLAN, MPEG4, 802.11b
PM, Server PM, Internet..
Title of the Paper: Fair Sharing Using Real-time Polling Service to
Adaptive VBR Stream Transmission in a 802.16 Wireless Networks
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Authors:
Chih-Peng Lin,
Hsing-Lung Chen
Abstract: The Worldwide
Interoperability for Microwave Access system’s (WIMAX, IEEE 802.16) broadband
networks is an attractive solution for high-bandwidth wireless access
network. In the context of a wireless broadband access network, the term open
real-time access implies the ability of multiple service BS (base station) to
share the deployed access network infrastructure to make available to the SSs
(subscribe Station). This paper contains brief variable rate control
strategies for real-time multimedia VBR (Variable Bit Rate) service frame
over IEEE 802.16 broadband networks. A data rate control mechanism is derived
for the case where the downlink channel provides real time polling bandwidth
allocation service while keeping the traffic rate parameter constant. The
paper shows that common queue scheduling algorithms have some bandwidth
allocation fairness problems for real time polling under the WIMAX system
(IEEE 802.16) MAC layer. In other words, the use of a VBR real-time polling
service by a WIMAX system results in additional access latency jitter and
bandwidth allocation disorder in the transmitted variable data rate of a
multimedia stream, during the base station’s regular time interval polling of
Subscribe Station (SSs) for the contention bandwidth request period. However,
this scheduling algorithm solves SSs contented bandwidth resource problems,
depending on the real-time polling service (rtPS) quality of service function
under ranging response non-contention polling period, as the adopted fairness
bandwidth allocation max-min algorithm is the only time constraint condition
for transmitting real-time multimedia video or VOIP in the 802.16 wireless
broadband environment. In addition, we utilized an NS2 simulation to analyze
VBR stream capacity, and show that the extended-rtPS by fairness Max-Min
algorithm can support more multimedia stream users than other rtPS scheduler
algorithms.
Key–Words: WIMAX, extend-rtPS,
rtPS, MAC, fairness Max-Min algorithm, VBR, base station, subscribe Station.
Title of the Paper: Improved Integral Channel Allocation Algorithms
in Cellular Communication Systems Enabling Multimedia QoS Services
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Authors:
P. M. Papazoglou, D. A. Karras, R. C. Papademetriou
Abstract – While bandwidth management in cellular communication systems has
been thoroughly examined for voice channel admission by developing several
DCA (Dynamic Channel Assignment) strategies, there are a few only efforts
investigating assignment and management of multimedia enabling channels in
wireless communications. However, the increasing demand for these advanced
services in cellular networks such as data, MMS and video transfers raises
the problem of efficient bandwidth management in terms of channel assignment
meeting QoS criteria. Several algorithms for supporting QoS services have
been presented in the literature based mainly on bandwidth reservation and
capacity management for enabling efficient handoff over cellular networks. The
goal of this paper is to develop and investigate, however, novel integral DCA
algorithms for supporting data (e.g. files) and video (video viewing, video
conference) transmission with Quality of Service (QoS), and their evaluation
through a prototype advanced statistical simulation environment for cellular
communications. Moreover, we analyze the dynamic and distributed channel
allocation strategies for enabling advanced multimedia services based on
signal purity measures and interference measurements. Finally, the
performance of these suggested algorithms evaluated through a proposed
prototype simulation environment is discussed.
Key-words: Cellular network, DCA,
Quality of Service, signal measurements, multimedia services, simulation.
Title of the Paper: On a New Generation of Event Scheduling
Algorithms and Evaluation Techniques for Efficient Simulation Modelling of
Large Scale Cellular Networks Bandwidth Management Based on Multitasking
Theory
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Authors:
P. M. Papazoglou, D. A. Karras, R. C. Papademetriou
Abstract – There are many research efforts for improving bandwidth management
in wireless communication systems based mainly on DCA (Dynamic Channel
Allocation) Schemes designed and evaluated through various Simulation models
which, however, use a common simulation model architecture coming from
queuing theory. Although much attention has been paid to Channel Allocation
Mechanisms there are few only efforts related to the corresponding simulation
models. These models consist of various critical components including network
services models and the simulation model architecture organizing network
events scheduling, network events handling and network performance
evaluation. One of the most critical components is the event scheduling
mechanism, which reflects network events as they happen in a real network and
which has not been investigated in depth regarding its performance. The state
of the art event scheduling mechanism called Calendar Queue (CQ) schedules
events for later execution based on the corresponding time stamps of each
generated event. The major drawback of this approach is that the generated
events are executed only sequentially due to progressive time stamps. On the
other hand, events in a real wireless network happen concurrently and so the
state of the art mechanism can not reflect such conditions. The goal of this
paper is to propose an alternative novel real time scheduling mechanism based
on a synthesis of multitasking theory and queuing theory techniques, which
could be involved in generating and investigating a new generation of event
scheduling algorithms suitable for simulation modelling of cellular networks
bandwidth management. This mechanism is analyzed through multitasking theory
tools and is shown to face effectively the concurrent nature of the generated
network events providing an efficient solution to the Calendar Queue problem.
Key-words: Multitasking, Network events,
Scheduling, Simulation, Cellular network, Bandwidth Management.
Title of the Paper: Fractal Superlattice Cover with Variable
Lacunarity For Patch Antenna Directivity Enhancement Analysis and Design
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Authors:
Ahmed Ali, Herve Aubert
Abstract: - The transmission spectrum of fractal polyadic Cantor super
lattice exhibits sharp peaks within forbidden frequency gaps. This property
has been exploited by placing such self-similar multi-slab structure in the
far field radiation region above a radiating element such as a patch antenna
to maximize its directivity at the corresponding transmission peak. A patch
antenna having directivity of 30 dBi is developed. The design and
optimization of the multi-slab structure is achieved using a doubly recursive
algorithm. The effect of changing the fractal lacunarity and/or the stage of
growth on the transmission characteristics has been studied in both the spectral
and spatial domains. Based on accurate analytical expressions for the cover
spectral and spatial transmission coefficient, a novel interpretation for the
antenna radiation pattern is presented. The antenna including the cover
structure is simulated using the moment method-based software tool IE3D. The
effect of varying the lacunarity and stage of growth on the spectral and
spatial transmission characteristics has been studied analytically using a
Matlab program.
Key-Words: - transmission
spectrum, self-similar structures, fractal lacunarity, fractal dimension,
stage of growth, antenna directivity, Computer-Aided Design (CAD), radiation
pattern.
Title of the Paper: Enhancing Medication Safety and Reduce Adverse
Drug Events on Inpatient Medication Administration using RFID
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Authors:
Chun-Liang Lai, Shou-Wei Chien,
Shiu-Ching Chen, Kwoting Fang
Abstract: - At any time, over 1.4
million people worldwide are suffering from infections acquired in hospital. Approximate
380,000 to 450,000 preventable Adverse drug events (ADEs) occurring annually
in the United States. Therefore, patient safety has become a serious global
public health issue. The purpose of this paper attempts to improve medication
safety and reduce ADEs using RFID technology. For improvement of medical
service quality in hospitals and reducing medication error, adopting RFID
technologies has progressively become a trend. Medication errors and ADEs
could be prevented by building a safer healthcare system. Accordingly, we
developed the RFID on Inpatient Medication Administration System (RIMAS) and
reengineering the inpatient medication processes. The RIMAS system
integrating RFID into the existing Hospital Information Systems (HIS) may
improve the efficiency of hospital management and medication safety, as well
as decrease the risk of adverse drug events thereby increase higher quality
of patient care.
Key-Words: - RFID, Patient safety, Medication
safety, Medication error, Adverse drug events.
Title of the Paper: Adjacent Channel Interference Analyses in TETRA
Direct Mode Operation
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Authors:
Andrej Hrovat, Tomaz Javornik, Gorazd Kandus
Abstract: - The present paper
analyzes adjacent channel interference in TETRA Direct Mode Operation (DMO)
for indoor and outdoor environments. To determine minimal stay-away distance
and interference area propagation model is used. Thus, a brief overview of
free space, Bacon and CEPT SE21 propagation models, mentioned in the TETRA
DMO standard is given and two-ray and multi-wall models are described and
evaluated by field measurements. We found out, that the two-ray model is
suitable for fast estimation of the TETRA DMO signal coverage in open flat
area while the multi-wall model, taking into account the attenuation of walls
between transmitter and receiver, gives good estimate of the signal levels
for indoor applications. Those two models were used for the interference
analyses. According to the calculated results two-ray model gives rather
pessimistic values of the stay away distance and interference area in open
flat areas while multi-wall model is appropriate for the interference
calculation inside buildings that are not surrounded with the high structures
causing additional ray reflections back into the interior of the analyzed
building.
Key-Words: interference,
propagation, path loss, TETRA Direct Mode Operation, two-ray model,
multi-wall model, radio signal coverage, stay-away distance
Issue 11, Volume 7, November 2008
Title of the Paper: Performance Analysis of Hybrid SCM/OSCDM System
using the Khazani-Syed (KS) Code
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Authors:
R. K. Z. Sahbudin, M. K. Abdullah
Abstract: - This paper proposes a hybrid subcarrier multiplexing/optical
spectrum code division multiplexing (SCM/OSCDM) system for the purpose of
combining the advantages of both techniques. Optical spectrum code division
multiple access (OSCDMA) is one of the multiplexing techniques that is
becoming popular because of the flexibility in the allocation of channels,
ability to operate asynchronously, enhanced privacy and increased capacity in
bursty nature networks. On the other hand, subcarrier multiplexing (SCM)
technique is able to enhance the channel data rate of OSCDMA systems. The
system utilizes a new unified code construction named KS (Khazani-Syed) code
based on the Double Weight (DW) and Modified Double Weight (MDW) codes. This
paper also presents a new detection technique called Spectral Direct Decoding
(SDD) detection technique for the OSCDM. SDD is effective in rejecting the
unwanted signals that interfere with the wanted signals. This results in
reduced receiver complexity and improved the performance of the hybrid system
significantly.
Key-Words: - Hybrid SCM/OSCDM,
Khazani-Syed (KS) code, multiple access interference, phase-induced intensity
noise.
Title of the Paper:
Cortical Signal Recording using an Economical Microelectrode Fabricated on
Printed Circuit Board
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Authors:
Yao-Ming Yu, Rong-Chin Lo
Abstract: - This work presents a simple, flexible and economical microwire
array electrode for extracellular cortical recordings. The proposed procedure
is relatively simple, even for a novice worker to implement in-house. These
main steps include design and sculpturing PCB, straightening microwires,
connecting PCB pattern, arraying and soldering microwires and packaging the
microelectrode. A practiced researcher can assemble the microelectrode in
about two hours and implant it in approximately three. The mass of this
assembled microelectrode is 1.96g. The cost of the materials in the entire
array is less than US$1.5, and the array is suitable for implantation in the
cortex of rats for neurophysiology studies. In this study, electrochemical
impedance spectroscopy is also applied to measure the impedance and the phase
between the electrode and the electrolyte, and then to obtain an equivalent
circuit. The improved microwire array electrode is adopted to record the
extracellular cortical signal of cerebrum. The microwire array electrode can
be fabricated and used for multi-site, multiple single-unit recording
experiments.
Key-Words: - Microelectrode, Printed circuit board, Flexible flat
cable, Extracellular, Electrochemical impedance spectroscopy
.
Title of the Paper: Optimum
Control Using Signal Processing in Integrated Aerospace navigation systems
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Authors:
Ayman Al-Lawama, Abdel-Rahman Al-Qawasmi, Omar Al-Ayasrah
Abstract:-The global – air – navigation telecommunication network is an integrated
system which joins telecommunication, navigation, and observation. This
integrated system provides communication in real-time scale between any two
inverse points .Direct and indirect measurement ( DIM ) of basic navigational
parameters of aircraft movement ( position , velocity , acceleration ,….. etc
) should be done accurately and precision . This paper provides general
theoretical fundamentals of Optimum Control (OC) of processed signal in
integrated navigational systems to obtain relatively simple and practically
convenient relations for calculating maximum accuracy. The well known maximum
probability method is used to obtain Optimum Complex Evaluation (OCE) for the
processed results of Unequal Accuracy (UA) measurements .Two lemmas are considered
for absolute concepts and ratio errors in DIM. Features of the proposed
method are illustrated using the simplest case of two measurement (m=2) and
then generalized using the method of induction for (m>2). The essential
conditions of existence theorem of optimum integration (OI) are proved for
these problems. Theoretical regulations of OI are illustrated using the
results of experiment, numerical examples and graphics. Through the results
of investigations, conclusions are formulated and practical recommendations
are developed for the use of OI.
Key-Words: - aerospace navigation
systems, Optimum control, DIM measurements, complex evaluation.
Title of the Paper: Radiation
Conductance and Pattern of Array Antenna on a Non-Confocal Dielectric-Coated
Elliptic Cylinder
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Authors:
A. Helaly, A. Sebak
Abstract- The formulation for the radiation pattern and conductance of axial
slots array antenna on a dielectriccoated elliptic cylinder is presented. The
coating is assumed to be non-confocal. The analytical solution, given here,
is based on the eigen function technique and the addition theorem of Mathieu
functions. The excited apertures are assumed to generate a TM polarized wave.
Accordingly, the obtained series solution is truncated to generate numerical
results. Sample of calculated azimuthal radiation patterns and radiation
conductance are presented for different antenna and coating parameters. The
elliptic cylinder has one extra degree of freedom compared to a circular
cylinder to control the radiation pattern and conductance. The computed
results show the flexibility of the antenna to control the shape and direction
of its radiation pattern by changing the frequency, the excitation, the
coating thickness of the cylinder, and the constitutive parameters of the
coating.
Key-Words: Axial slot antennas,
non-confocal coating, analytical methods.
Title of the Paper: Developing Multimedia Instructional Material
for Robotics Education
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Authors:
Eric Zhi Feng Liu, Chan Hsin Kou, Chun Hung Lin, Shan Shan Cheng, Wen Ting
Chen
Abstract: - To develop the multimedia instructional material for robotics
education, this study tried to develop a multimedia instructional material
for robotics education and applied to a course to figure out the usability
and utility. In this multimedia instructional material, there are four main
sessions: adventure of the robot, assembly, programming, and demonstration
video. The multimedia instructional material was designed to motivate
students by an interesting adventure story, to introduce the assembly of a
robot to complete the mission introduced in the adventure story, to introduce
the programming of the operations of a robot to command the robot to complete
the mission introduced in the adventure story, and to demonstrate the process
of completing a mission. Finally, triangulation method was applied in this
study to assess the user perception of the multimedia instructional material
for robotics education. The triangulation data was obtained by observation,
qualitative analysis of feedback generated by a class blog, and quantitative
analysis of student perception of the multimedia instructional material for
robotics education. Accordingly, the analysis results indicated that the
multimedia instructional material for robotics education was effective and
achieved high student satisfaction.
Key-Words: - LEGO, MINDSTORMS NXT,
Robot, Robotics education, Programming, Assembly.
Title of the Paper: Defected Ground Structures (DGS) and Uniplanar
Compact- Photonic Band Gap (UC-PBG) Structures for Reducing the Size and
Enhancing the Out-of-Band Rejection of Microstrip Band pass Ring Resonator
Filters
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Authors: Heba
B.
El-Shaarawy, Fabio
Coccetti, Robert
Plana, Mostafa El-Said, Essam
A.
Hashish
Abstract: - This paper addresses a modified bandpass ring resonator filter
providing compact size, low insertion-loss, wide bandwidth, sharp rejection
and suppressed higher order modes. Typically, ring resonator filters suffer
from large occupation area and limited out of band rejection. These
limitations are tackled in this work by means of a threefold approach. On the
one hand, the use of internal folded stubs allows the exploitation of the
internal ring area yielding more than 70% of overall size reduction with
respect to conventional orthogonal straight stubs solution. On the other
hand, the introduction of Defected Ground Structures (DGS) and Uniplanar
Compact-Photonic Bandgap (UC-PBG) structures, formed by etching patterns in
the ground plane of the filter, enhances by great extends the rejection of
higher order modes providing a stopband that reaches 4.7 GHz beside offering
a further advantage in terms of size reduction. The two approaches are first separately
validated and then simultaneously combined to provide an optimized filter
design. Finally, a solution employing via holes to replace the tuning stubs
is explored in order to extend the lower stopband. EM simulation, equivalent
circuit model, as well as measurement results validate the followed design
approach and are in excellent agreement within each other.
Key-Words:
- photonic bandgap, ring resonator, bandpass filter, fractional bandwidth,
stopband, insertion loss.
Issue 12, Volume 7, December 2008
Title of the Paper: A Perfect QoS Routing Algorithm for Finding the
Best Path for Dynamic Networks
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Authors:
Hazem M. El-Bakry, Nikos Mastorakis
Abstract: It is highly desirable to
protect data traffic from unexpected changes as well as provide effective
network utilization in the internetworking era. In this paper the QoS
management issue that utilizing the active network technology is discussed.
Such algorithm is based on the proposed work presented in [15]. Active
networks seem to be particularly useful in the context of QoS support. The
Active QoS Routing (AQR) algorithm which is based on On-demand routing is
implemented incorporating the product of available bit rate and delay for
finding the best path for dynamic networks using the active network test bed
ANTS. It is inferred that with background traffic, the AQR finds alternative
paths very quickly and the delay and subsequently the jitter involved are
reduced significantly. In this paper the variant of AQR implemented is
demonstrated to be more useful in reducing the jitter when the overall traffic
in the network is heavy and has useful application in finding effective QoS
routing in ad-hoc networks as well as defending DDoS attacks by identifying
the attack traffic path using QoS regulations. The main achievement of this
paper is the fast attack detection algorithm. Such algorithm based on
performing cross correlation in the frequency domain between data traffic and
the input weights of fast time delay neural networks (FTDNNs). It is proved
mathematically and practically that the number of computation steps required
for the presented FTDNNs is less than that needed by conventional time delay
neural networks (CTDNNs). Simulation results using MATLAB confirm the
theoretical computations.
Key-Words: Routing Algorithm, Data
Protection, Best Path, Dynamic Networks, Fast Attack Detection, Neural
Networks
Title of the Paper: Improving Performance on Mobile Ad Hoc Networks
by Using Proxy Service
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Authors:
G. E. Rizos, D. C. Vasiliadis, E. Stergioy
Abstract: In this paper, we present
the role of proxy service in a MANET environment. MANET is specifically
characterized by high mobility of network nodes and frequent changes of direct
visibility. High dynamicity affects the design and implementation of
distributed applications by significantly increasing their complexity, to
consider not only routing and node configuration issues, but also the possible
mobility of software components and the loss of direct connectivity during
service provisioning. The proxy role is assigned dynamically in a completely
decentralized way. Proxies exploit code mobility to install only when and
where needed. In this work, we estimate and compare the performance of routing
protocols for ad-hoc networks, namely Ad Hoc On-Demand Distance Vector
protocol (AODV) and Dynamic Source Routing (DSR). We use the file transfer
protocol to measure the performance of our model. The protocol provides file
downloading from a dynamically discovered service component available in a
MANET locality, even if the server moves during file transfer
Key-Words: Mobile Ad Hoc Networks (MANET),
routing protocols, AODV, DSR, Service PROXY, file transfer protocol
Title of the Paper: Evaluating Multicast Routing Algorithms'
Performance and Execution Time
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Authors:
Dan Mancas, Ecaterina-Irina Manole, Nicu Enescu
Abstract: In this paper, an
evaluation of the network routing algorithms is made. Problems that arise in
routing are treated, each presented in different scenarios in order to obtain
a result in comparing different topologies. The comparison analysis is
pursuing obtaining a result over the performance of the network. In order to
measure performance, the costs of a network and the delays are aimed. After
that, the topology effect is presented. In matter of performance, topology and
blocking problems are strongly related. So an analysis of the blocking
probability is also presented. As conclusions, solutions for the presented
scenarios and also for other important scenarios are given. In all these
algorithms the time problem was not yet consider until now, so the average
execution time is finally analyzed.
Key-Words: Multicast, unicast,
routing algorithm, evaluation, traffic, topology, cost, delay, capacity, load,
execution time
Title of the Paper: Algorithms for Locating GPS Coordinates on PDA
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Authors:
Nicolae-Iulian Enescu, Dan Mancas, Ecaterina-Irina Manole
Abstract: The purpose of our
research is to find algorithms for loading large maps on PDA and place on it
the geographical location given by latitude and longitude. C++ and C#
programming languages have been used for implementation. It was elaborated a
software which runs on PDA with Windows Mobile 2003 OS and implements
algorithms for finding the coordinate on a map represented like a TIF image.
The application must localize the coordinates known by longitude and latitude
over a given image in TIF format which can represent a map with scale 1:200000
or 1:25000. The map headers contain information that refers to map limit. An
algorithm that permits map synchronization when the value of current map is
out of limit it was necessary.
Key-Words: GPS, map, TIF,
coordinates, PDA, Windows Mobile 2003
Title of the Paper: A Survey on Wireless Sensor Networks Deployment
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Authors:
Zoran Bojkovic, Bojan Bakmaz
Abstract: In recent years extensive
research has opened challenging issues for wireless sensor networks (WSNs)
deployment. Among numerous challenges faced while designing architectures and
protocols, maintaining connectivity and maximizing the network lifetime stand
out as critical considerations. WSNs are formed by a large number of
resource-constrained and inexpensive nodes, which has an impact on protocol
design and network scalability. Sensor networks have enabled a range of
applications where the objective is to observe an environment and collect
information about the observed phenomena or events. This has lead to the
emergence of a new generation sensor networks called sensor actuator networks.
Approaches developed to query sensor-actuator networks (SANETs) are either
application-specific or generic. Application-specific SANETs provide limited
reusability, are net cost effective and may require extensive programming
efforts to make the network able to serve new applications. A WSNs should be
able to operate for long time with little or no external management. The
sensor nodes must be able to configurate themselves in the presence of adverse
situations. In this work, dealing with challenges for WSNs deployment, we
start with mobility-based communication in WSNs. Then, we introduce
service-oriented SANETs (SOSANETs) as an approach to build customizable SANETs.
In the second part, we describe localization systems and analyze self
configurability, situation awareness and intrusion detection system. In the
third part, we present wireless distributed detection as well as a model for
WSN simulation. Finally, conclusions and proposals for future research are
given.
Key-Words: Mobility-based
communication, sensor-actuator networks (SANETs), service oriented SANETs (SOSANETs),
wireless sensor networks (WSNs)
Title of the Paper: Trends in Interactive Services for Digital
Television Infrastructure
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Authors:
Bojan Bakmaz, Zoran Bojkovic
Abstract: The challenge of
multimedia communications is to provide applications that integrate text,
image, and video information and to do it in a way that presents ease of use
and interactivity. This paper deals with trends in interactive services for
digital television infrastructure from the point of view of return channel and
flow of information. We start with a short overview concerning previous work
on this hot topic. Then, we deal with the interactive services in digital
television infrastructure. After that adequate solutions for return channel
are presented. Finally, flow of information in the interactive TV services for
mobile devices is described including applications on mobile devices.
Key-Words: Digital TV, DVB, flow of
information, interactive services, mobile devices, return channel
Title of the Paper: New Algorithms for QoS Performance Improvement
in High Speed Networks
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Authors:
Radu Dobrescu, Daniela Hossu, Stefan Mocanu, Maximilian Nicolae
Abstract: In this paper is
addressed the issue how to provide QoS control and improve performance in high
speed Optical Burst Switching (OBS) networks. In order to provide better
proportional differentiated services are proposed new algorithms: a burst
assembly algorithm (named adaptive timer-based) with traffic shaping functions
and a Delayed Burst Assignment (DBA) scheme, both able to reduce the variance
of assembled traffic and to improve the burst loss performance. A precise
analytical model to study the performance of the assembled traffic in high
speed networks is also presented. The simulation results show that the
proposed algorithms have better performance in terms of edge buffering delay
and can lighten burst loss ratio for TCP flows of the OBS network.
Key-Words: Optical Burst Switching
networks, QoS control, deterministic and statistical services, integrated and
differentiated services, traffic burstiness, burst loss performance
Title of the Paper: Record Path Header for Triangle Routing Attacks
in IPv6 Networks
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Authors:
Su-Kit Tang, Kin-Yeung Wong, Kai-Hau Yeung
Abstract: Triangle routing is one
of the serious attacks to the Internet infrastructure. It can be caused by
malicious routers which misroute packets to wrong directions. This kind of
attacks creates network problems such as network congestion, denial of service
and network partition and results in degrade of network performance. This
paper gives a comprehensive study on how the path analysis combats the
triangle routing attacks. We discuss the method, implementation and limitation
of path analysis to detect triangle routing in IPv4 network. We also discuss
the implementation of path analysis in IPv6 by proposing a new extension
header, called Record Path Header.
Key-Words: IPv6, Infrastructure,
Routing, Attack
Title of the Paper: Constructing the Multi-Agents Communication
Model to Implement Dynamic Intelligent System
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Authors:
Steven K. C. Lo, Jen-Chih Lin, Huan-Chao Keh, Yi-Hung Lin, Wan-Chih Wang
Abstract: The intelligent agent
communication mechanism is designed to execute under background when the
application drives an event trigger and the telephony technologies have been
rapidly grown up and provide the multi-functions and good interactive user
graphic interface (GUI). The hardware of cellular phone device also provides
the light , small size with wide screen, more convenient, stable, flexible and
available to easy obtain the information from internet world wide web (WWW).
According to magazine reporting, most of people have an above 2G cellular
phone at least in Taiwan and use the multi-function to retrieve data from
internet. In this paper, it is implemented the intelligent communication agent
[3, 6, 8, 12] mechanism characterizes and integrated the RFID mechanism to
establish a communication channel to automatically transmit data packets from
source site to destination site. Using the RFID mechanism to obtain the data
from tags through the reader/interrogator is the RFID agent primary task.
Key-Words: Intelligent Agent,
cellular phone, RFID, Single-agent system, Multi-agent system
Title of the Paper: A Real-Time Intrusion Detection Algorithm for
Network Security
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Authors:
Hazem M. El-Bakry, Nikos Mastorakis
Abstract: E-government is an
important issue which integrates existing local area networks into a global
network that provide many services to the nation citizens. This network
requires a strong security infrastructure to guarantee the confidentiality of
national data and the availability of government services. In this paper, a
framework for network intrusion detection systems is presented. Such framework
utilizes data mining techniques and is customized for the E-Government Network
(EGN). It consists of two phases: an offline phase in which the intrusion
detection system learns the normal usage profiles for each local network
domain, and a real time intrusion detection phase. In the real time phase,
known attacks are detected at a global layer at the EGN perimeters while
normal behavior is filtered out at a local layer defined for each LAN domain.
Clustering is used to focus the analysis on the remaining suspicious activity
and identify whether it represents new intrusive or normal behavior. This
framework is intended to detect intrusions in real-time, achieve low false
alarm rates, and continuously adapt to the environment changes and emergence
of new behavior. This research is a development for the work presented in
[22,23]. The main achievement of this paper is the fast attack detection
algorithm. Such algorithm based on performing cross correlation in the
frequency domain between data traffic and the input weights of fast time delay
neural networks (FTDNNs). It is proved mathematically and practically that the
number of computation steps required for the presented FTDNNs is less than
that needed by conventional time delay neural networks (CTDNNs). Simulation
results using MATLAB confirm the theoretical computations.
Key-Words: Fast Intrusion
Detection, Clustering, Data Mining, E-Government, Cross correlation, Frequency
domain, and Neural Networks
Title of the Paper: A Blind Source Separation based Cryptography
Scheme for Mobile Military Communication Applications
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Authors:
Nikolaos Doukas, Nikolaos V. Karadimas
Abstract: Security in digital
transmission is an increasingly interesting topic in a number of fields. In
many cases however, the need for security is forfeited due to the high
complexity of commonly used cryptosystems. The use of the underdetermined
source separation problem as a basis for a cryptographic mechanism has
recently been proposed. Many cryptographic algorithms, such as public key
algorithms which based a common military application, use as a basis
intractable number theory problems (such as integer factorization and
exponentiation). Underdetermined blind source separation is also shown to have
the potential to serve this purpose, as the difficulties of deriving an
analytic solution to this problem have been extensively documented. This paper
presents a study of blind source separation based encryption, proposes some
further improvements in approaches that have already been presented and
illustrates the application of the improved algorithms in the paradigm of
secure speech communication. The proposed scheme is related to Independent
Component Analysis Concepts. A preliminary cryptanalysis study is presented
that verifies the adequacy of the new scheme for use in mobile military
communication units and other applications where security is critical. The
proposed scheme is also shown to be immune to some of the attacks to which
existing methods were believed to be vulnerable.
Key-Words: Blind source separation,
encryption, secure digital communications
Title of the Paper: Pulse Shaping in Non-Coherent DLL Tracking of
CDMA Signals
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Authors:
Mohamed Adnan Landolsi, Ganiyu B. Hussain
Abstract: The paper analyses the
impact of pulse shaping on code tracking for direct-sequence code division
multiple access (DS-CDMA) signal synchronization using non-coherent delay-lock
loops (NC-DLL). The dependency of the residual timing error variance on the
chip waveform is emphasized, and the performance of several non-rectangular
pulse shapes is presented. The design of optimized chip waveforms for
minimizing the DLL tracking error variance is then formulated using a cost
function expressed in frequency-domain and highlighting the dependency of the
tracking jitter on the chip waveform Fourier transform. A solution methodology
is introduced based on the use of Prolate Spheroidal Wave Functions. Some
illustrative design examples are presented, establishing theoretical limits
for the best achievable performance (minimum jitter). In particular, it is
shown that the half-sine and Hamming pulses are near-optimum when considering
pulses with 99% and 99.9% in-band power bandwidth occupancies, respectively.
Key-Words: CDMA, DLL, Code
tracking, Tracking jitter, Chip waveform shape
Title of the Paper: A Techno-Economic Model for the Optimized
Introduction of ADSL Technology in an Urban Area
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Authors:
Kleanthis Noou, Vassilis Stylianakis, Konstantinos Siassiakos, Konstantinos
Salpasaranis, Stavros Lazarou
Abstract: This paper optimizes the
introduction of broadband internet service in an existing PSTN network, by the
means of a techno-economical model. The proposed model determines the optimal
timing of introduction of ADSL technology to an urban telephone network, as
seen by the Network Access Provider perspective. The implementation strategy
is determined on the basis of the maximization of the total income while
keeping capital expenditures under a given budget. Costs and Incomes are
predicted based on current prices of both charging rates and broadband
equipment. The feasible policies concern the evolution of the Central Offices
of the urban network, as well as the introduction of centralized equipment,
such as routers and aggregators. The model first determines the number of
feasible policies and the costs associated with each one, using inputs
concerning the network status, i.e., the number, position and capacity of
exchanges and links, broadband services demand predictions, technical
specifications as well as pricing predictions and, by the means of a charging
(revenues) model produces the alternative policies for each Central Office
(CO) as well as for the introduction of routers and aggregators along with
their corresponding costs and incomes. These results are then fed to the
second part of the model, which, using the costs and revenues associated with
each alternative policy for each CO and for each type of centralized
equipment, selects the overall optimal network policy, by estimating the most
profitable combination of CO policies, one for each, as well as the policies
concerning the introduction of routers and aggregators, by keeping the sum of
the corresponding costs under certain limits. The overall policy is determined
by the means of an IP (Integer Programming) algorithm. The Integer Programming
algorithm consists of an objective function maximized with respect to a number
of constraints. The model was implemented in the case of the urban telephone
network of Patras/ Greece, using several realistic assumptions for the
estimation of the costs and revenues, as well as typical current
configurations for estimating the costs involved. The results obtained proved
the validity of the model.
Key-Words: ADSL, Integer
Programming, Techno-Economic Model
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