WSEAS CONFERENCES. WSEAS, Unifying the Science

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 Volume 7, 2008
Print ISSN: 1109-2742
E-ISSN: 2224-2864








Issue 1, Volume 7, January 2008

Title of the Paper:  A Simple Adaptive p-persistent MAC Scheme for Service Differentiation and Maximum Channel Utilization


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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, IEEEs 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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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.


Title of the Paper: Analysis of Opposing Stream Effect on the Non-uniform Optical Fiber Communication Lines


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


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


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


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


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


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


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


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


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


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


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


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


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)


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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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