WSEAS CONFERENCES. WSEAS, Unifying the Science

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9, 2010
Print ISSN: 1109-2742
E-ISSN: 2224-2864








Issue 1, Volume 9, January 2010

Title of the Paper: On the Minimum Number of Users for the Generation of H-ss Traffic in a Simulation Scenario


Authors: Candelaria Sansores Perez, Luis Rizo Dominguez, Julio Cesar Ramirez Pacheco

Abstract: Several simulation and measurement studies have reported the well-known network traffic self-similarity and long-range dependency and the consequences for network performance. In the context of simulation, however, the impact of the number of sources has not been sufficiently emphasized for the generation of synthetic selfsimilar traffic. In this paper we describe a simulation scenario suitable for the testing of performance issues under self-similar traffic. Our analysis was centered on the effect of traffic aggregation over the self-similarity degree, determining the necessary number of sources to approach the verified relation H = (3 ? min )/2. Besides, we highlighted the performance of several Hurst parameters estimators for this type of simulation scenarios, identifying the most suited ones.

Keywords: Self-similar traffic, Heavy-tail distributions, Performance evaluation, Simulation

Title of the Paper: Problem of Assignment Cells to Switches in a Cellular Mobile Network via Beam Search Method


Authors: Cassilda Maria Ribeiro, Anibal Tavares Azevedo, Rodolfo Florence Teixeira Jr.

Abstract: The problem of assigning cells to switches in a cellular mobile network is an NP-hard optimization problem. So, real size mobile networks could not be solved by using exact methods. The alternative is the use of the heuristic methods, because they allow us to find a good quality solution in a quite satisfactory computational time. This paper proposes a Beam Search method to solve the problem of assignment cell in cellular mobile networks. Some modifications in this algorithm are also presented, which allows its parallel application. Computational results obtained from several tests confirm the effectiveness of this approach to provide good solutions for medium- and large-sized cellular mobile network

Keywords: Combinatorial Optimization. Assignment problem. Beam Search Method. Cellular Network

Title of the Paper: The Performance Analysis of MRC Combiner Output Signal in the Presence of Weibull Fading and Shadowing


Authors: Petar Nikolic, Dragana Krstic, Zoran Popovic, Dusan Stefanovic, Mihajlo Stefanovic

Abstract: The performance of dual diversity systems in the presence of Weibull and shadowing over two uncorrelated branches will be presented in this paper. The performance measures of fading communication systems such as probability density function (PDF) of signal to noise ratio (SNR), Amount of fading (AF), and Outage probability (Pout) will be calculated and graphically represented for Maximal Ratio Combining. The results will be shown graphically for different signal and fading parameters values. They will be compared with respect to the kind of shadowing which is with log-normal or Gamma distribution.

Keywords: Weibull fading, Log-normal fading, Gamma fading, Maximal Ratio Combining, Amount of fading, Outage probabilty

Title of the Paper: A Survey on MPEG-4 Standard and Digital Television Deployment


Authors: Zoran Bojkovic, Bojan Bakmaz

Abstract: MPEG-4 standard has been developed to support a wide range of multimedia applications. It provides users a new level of interaction with visual contents, including techniques to view, access and manipulate objects rather than pixels with great error robustness at a wide range of bitrates. The object-based representation paradigm make MPEG-4 a standard that may find application from low bitrate personal mobile communications to high quality studio production. One topic common to most applications is the need for supporting interactivity with different kind of data. A prime example is the introduction of Digital TV (DTV) instead of analog with obvious direct benefit such as improved quality and reliability. DTV delivers interference and distortion free audio and video signals, while achieving much higher spectrum efficiency than analog television. Agreements for the DTV transition are being implemented with different emphasis in various countries, depending on network and station arrangements, government regulations, and market conditions. DTV increasingly impacts broadcasters, consumers and many related industries. The DTV systems that are now available worldwide, not only deliver crystal-clear picture, and high quality sound, but they also provide various innovative new services and programs, such as electronic program guide, personalized advertisements, control, IP encapsulation, data broadcasting various interactive services. High Definition (HD) programming requires installation of completely new production and distribution equipment and systems. This is a major capital investment for a broadcaster. This work seeks to provide an overview of the influence of MPEG-4 standard on DTV from a perspective in Europe. The first part deals with some practical elements of the MPEG-4 standard. The focuses are on the set of technologies together with visual bitstream. The second part describes DTV development including Digital Video Broadcasting (DVB) activities and achievements as well as high definition system origination for DTV. Finally, the third part describes control and encoding for DTV including the corresponding services.

Keywords: Coding, DTV, DVB, H.264/AVC, HDTV, MPEG-4 standard

Title of the Paper: Optimal Placement of Base Stations in a Two Tiered Wireless Sensor Network


Authors: B. Paul, M. A. Matin, M. J. Showkat, Z. Rahman

Abstract: The optimal placement of base stations in a two tiered wireless sensor network (WSN) can reduce the energy consumption of sensor nodes (SN) and thus can improve network lifetime. In our paper, we address the base station location problem and provide a geometrical solution introducing a new concept called node partitioning technique. An algorithm based on the geometrical approach is also provided in the paper.

Keywords: Wireless sensor network, Minimum enclosing circle, Node partitioning, Base station, Cluster, Geometry

Title of the Paper: E-learning: Analysis of Online Discussion Forums in Promoting Knowledge Construction through Collaborative Learning


Authors: Nor Fariza Mohd. Nor, Norizan Abdul Razak, Jamaluddin Aziz

Abstract: Extensive discussions and debates about the advantages of using technology to create a shared space among learning participants have been presented in studies in the field of e-learning. One of the approaches in using or adopting technology for learning is through the use of online discussion forums, which as reported has beneficial impact on the teaching and learning process. Online discussion forum is also a form of learning through networking which provide opportunities for students to seek, obtain, and share information. Therefore, students’ participation and interaction in the forum can provide some insight into how they learn about a course in a virtual environment. In addition, it is also essential to consider how online discussion forums may promote knowledge constructions in students.This study examines preliminary data of an online discussion forum in a course at Masters level (MA) in order to investigate if there is evidence of shared construction of knowledge among students through collaborative learning behaviours. The findings indicate that the students actively processed and reviewed the postings in the online discussion forums. They also relate their postings to what they have learned in the lectures, besides providing links to relevant websites for further reading. Therefore, there is evidence that the students worked collaboratively in order to respond to the postings based on the topics presented during the lecture and tutorial. Finally, analysis of the students’ discourses indicate various phases of knowledge construction (based on the IAM model), which is a reflection of their cognitive thinking process.

Keywords: E-learning, content analysis, online forum discussion, knowledge construction, collaborative learning, asynchronous communication

Title of the Paper: A Design Rule for Inset-fed Rectangular Microstrip Patch Antenna


Authors: M. A. Matin, A. I. Sayeed

Abstract: In our paper, an inset-fed microstrip patch antenna has been designed and the dependency of resonant frequency on the notch gap and the feed line geometry has been studied. Our study suggests that a narrower notch resulted in better impedance matching. A design rule has also been formulated and presented the performance of the proposed design.

Keywords: Inset-fed, microstrip antenna

Issue 2, Volume 9, February 2010

Title of the Paper: E-Management for Administrative Efficiency in Higher Education through Participatory Decision-Making


Authors: Fatimah Hashim, Gazi Mahabubul Alam, Saedah Siraj

Abstract: Though many organizations have developed their own approaches in ensuring reliable decision making processes, not many have used technology to ensure effective participatory based decision making. This paper presents a model that incorporates reliable participatory based decision making practices and quality management indicators through strategic use of technology - an initiative of a faculty in a higher institution of learning. The model, called QuESt (Quality E-management System), integrates web-based technologies into an interconnected system to enable decision making by all stakeholders at multi levels of responsibility. Discussion in this paper is first focused on the bureaucracy and participatory models of decision making, then moves on to the research context, description of QuESt and discussion of the features and functions of the system. The paper concludes with an assessment of the potentialities of the system in taking an organisation’s internal and external processes to the next level – using technology to ensure evidence based decision making, to interconnect staff roles and responsibilities and to use feedback to take appropriate action. Implications are drawn for knowledge advancement, policy making and practice.

Keywords: Participatory based decision making; E-management; accountability; efficiency, internal and external processes

Title of the Paper: Developing a Denotation Model from Luminance of Album Cover from 1980 to 1992 in Taiwan


Authors: Manlai You, Li-Min Chen

Abstract: Based on the luminance attribute of pop album cover, a diachronic study was conducted. It was argued that the denotation is significant related to the luminance attribute. The population of this study was those pop albums published from 1980 to 1989. In those years, this country was gradual opening up of political and economic stability. The sampled representative pop album covers were collected and put on the computer screen for conducting content analysis. The denotation and luminance attribute of each sampled album cover were also identified for statistical test. The relation between luminance and color was verified by applying regression technique. It was concluded that luminance could be predict 100 percent by the values of RGB colors. A logit regression was used to predict denotation of pop album cover from mean value of luminance and standard deviation of luminance. The C5.0 model was used to build a rule set and a decision tree for further illustrate the relation between luminance attribute and denotation.

Keywords: POP album cover, diachronic study, luminance attribute, denotation

Title of the Paper: Important Aspects of Using Geographical Information System


Authors: Marius-Constantin Popescu, Nikos Mastorakis

Abstract: This first part of the paper presents a short introduction in GIS technology and its application domains. The second part includes a classification of the GIS products, future research possibilities and a short presentation of equipments for data acquisition. Part three contains a list of the most attractive GIS projects undertaken in the world and in Romania.

Keywords: GIS, Areas to apply, Satellites

Title of the Paper: Comparative SAR Assessment in Adults and Children Exposed to Electromagnetic Fields of Radio Frequency Devices


Authors: Mimoza Ibrani, Luan Ahma, Enver Hamiti

Abstract: Exposure to radio frequency electromagnetic fields has raised scientific and public concern regarding possible adverse effects to people exposed to such radiation. At cellular mobile communication frequencies, the most important parameter used to assess human exposure to electromagnetic fields is SAR (Specific Absorption Rate). This paper will firstly address two exposure scenarios related to adult exposure to GSM electromagnetic fields : Human exposure to 900 MHz GSM base station electromagnetic fields, whereby with EMR-300 is measured field strength on different points located meters away from base station antenna. Using SAR prediction formula we have calculated induced SAR values for people located near base station antenna. The obtained results are compared with maximum permissible levels and basic restrictions of international safety standards. Human exposure to mobile phone GSM electromagnetic fields, whereby with a software (FDTD code) have simulated human head exposure to mobile phone radiation and have calculated Spatial Peak SAR over 1 g and 10 g of human body biological tissues. Secondly, in order to investigate comparison of radio frequency energy absorption by head of children and adults, the Spatial Peak SAR over 1g and 10g is calculated for: uniformly down-scaled adult head with increased dielectrical parameters compared to adult ones and uniformly down-scaled adult head with adult dielectrial parameters. SAR results are presented graphically and tabulary while comparative assessment is given in order to emphasize influence of head size and change of dielectrical parameters on radio frequency energy absorption by human tissues, and give possible answer whether children should be treated as special group regarding radio frequency exposure. Even not an all inclusive approach is considered, obtained results indicate that SAM may be considered conservative for assessment of children exposure compliance to radio frequency electromagnetic fields.

Keywords: Radio frequency, GSM, SAR, SAM, base station antenna, field strength, mobile phone, child, dielectrical properties

Title of the Paper: Fast and Secure Handover Schemes Based on Proposed WiMAX over EPON Network Security Architecture


Authors: Wen Gu, Stamatios V. Kartalopoulos, Pramode K. Verma

Abstract: In recent years, the integration of Worldwide Interoperability for Microwave Access (WiMAX) and Ethernet Passive Optical Network (EPON) has become one of the most promising broadband access solutions. The EPON network provides tremendous bandwidth while the WiMAX network can support mobility. Integration of PON and WiMAX combines the best of both technologies. However, the integration requires advanced secure mechanisms to overcome vulnerabilities of wireless mobile protocols. In this paper, we propose an end-to-end network architecture based on WiMAX over EPON networks, and we present a security framework that adopts the RSA protocol and the Extensible Authentication Protocol (EAP). We introduce three handover scenarios in the integrated network and propose the corresponding handover schemes. In the proposed handover schemes, we utilize a pre-authentication method for the authorization key (AK) pre-distribution, and we use the communication framework of the ranging step to implement mutual authentication between the subscriber and the mobile network. Through our analysis, we show that the proposed handover mechanisms can simplify and accelerate the handover process compared to the standard WiMAX handover scheme while keeping the handover procedure secure.

Keywords: WiMAX over EPON, Handover Security, Pre-authentication, Ranging

Title of the Paper: Imaginary Relativity


Authors: Mehran Rezaei

Abstract: The main goal of this paper is to present a theory, named Imaginary Relativity, which completes Einstein’s Relativity Theory. According to the recommended theory in this paper, the speed of light is not constant and absolute in an inertial frame. On the other hand, the speed of a light pulse in an inertial frame, moving with velocity u, equals to an imaginary value instead of the constant value c as it is considered in Einstein’s Relativity Theory.

Keywords: Imaginary relativity, Lorentz transformations, Imaginary energy, Wave particle duality, Space-time

Title of the Paper: Evaluating the Efficiency of Shortcut Span Protection


Authors: Sarah Ruepp, Lars Dittmann, Michael Berger, Thomas Stidsen

Abstract: This paper presents a comparison of various recovery methods in terms of capacity efficiency with the underlying aim of reducing control plane load. In particular, amethod where recovery requests are bundled towards the destination (Shortcut Span Protection) is evaluated can compared against traditional recovery methods. The optimization model is presented and our simulation results show that Shortcut Span Protection uses more capacity than the unbundled related methods, but this is compensated by easier control and management of the recovery actions.

Keywords: Resilience, Linear Programming, Simulation, Networking, Control Plane

Issue 3, Volume 9, March 2010

Title of the Paper: Towards 100 Gigabit Carrier Ethernet Transport Networks


Authors: A. Rasmussen, J. Zhang, H. Yu, R. Fu, S. Ruepp, H. Wessing, M. Berger

Abstract: Ethernet as a transport technology has, up to now, lacked the features such as network layer architecture, customer separation and manageability that carriers require for wide-scale deployment. However, with the advent of PBB-TE and TMPLS, it is now possible to use Ethernet as a transport technology, making the use of Ethernet as a convergence layer for Next Generation Networks a distinct possibility. Triple Play services, in particular IPTV, are expected to be a main drivers for carrier Ethernet, however, a number of challenges must be addressed including QoS enabled control plane, enhanced OAM functions, survivability and the increased bandwidth requirements of carrier class systems. This article provides an overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be realized in the framework of Carrier Ethernet. In addition we provide a case study on performing bit error rate (BER) measurements on the aggregated 100G stream.

Keywords: Carrier Ethernet, IPTV, T-MPLS, PBB-TE, NGN, BERT, 100G

Title of the Paper: Efficient Computational Information Geometric Analysis of Physically Allowed Quantum Cloning Attacks for Quantum Key Distribution Protocols


Authors: Laszlo Gyongyosi, Sandor Imre

Abstract: In secret quantum communications the best eavesdropping attacks on quantum cryptography are based on imperfect cloning machines. The incoherent attack, based on quantum cloning, is the most common eavesdropping strategy. Using a probe, the eavesdropper imperfectly clones the sender’s quantum state which keeps one copy and sends the other. The physically allowed transformations of Eve’s quantum cloner on Bob’s qubit can be described in terms of Completely Positive (CP), trace preserving maps. The map of the quantum cloner compresses the Bloch-ball, as an affine map. This affine map has to be a complete positive, trace preserving map, which shrinks the Bloch ball. The effects of a quantum cloner can be given in tetrahedron representation. In this paper we show a new, quantum information theoretical representation of eavesdropping detection, focused on the Four-state (BB84) and Six-state quantum cryptography protocols. We use a fundamentally new computational geometrical method to analyze the informational theoretical impacts of cloning activity on the quantum channel. The proposed algorithm uses Delaunay tessellation and convex hull calculation on the Bloch sphere, with respect to quantum relative entropy as distance measure. The improved core-set approach can be used to analyze efficiently the informational theoretical impacts of physically allowed quantum cloning attacks.

Keywords: Quantum Cryptography, Quantum Cloning, Quantum Informational Distance

Title of the Paper: Routing Protocol Extension for Resilient GMPLS Multi-Domain Networks


Authors: Anna Manolova, Sarah Ruepp, Ricardo Romeral, Sergio Rodriguez

Abstract: This paper evaluates the performance of multi-domain networks under the Generalized Multi-Protocol Label Switching control framework in case of a single inter-domain link failure. We propose and evaluate a routing protocol extension for the Border Gateway Protocol, which allows domains to obtain two Autonomous System disjoint paths and use them efficiently under failure conditions. Three main applications for the protocol extension are illustrated: reducing traffic loss on existing connections by exploiting pre-selected backup paths derived with our proposal, applying multi-domain restoration as survivability mechanism in case of single link failure, and employing proper failure notification mechanisms for routing of future connection requests under routing protocol re-convergence. Via simulations we illustrate the benefits of utilizing the proposed routing protocol extension for networks employing different resilient mechanisms (both protection and restoration), as well as for networks which have not employed any resiliency technique. We show the need for differentiated failure handling for improving network performance under failure situations. Furthermore, we draw parallel between different network parameters and the efficiency of the applied notification and survivability strategies in the network.

Keywords: Multi-domain, GMPLS, BGP, AS-disjoint, performance enhancement

Title of the Paper: Cooperative MIMO MAC Protocol using STTC in Wireless Sensor Networks


Authors: J. Vidhya, G. Kalpana, P. Dananjayan

Abstract: Sensor networks require robust and energy efficient communication protocols to maximise the network lifetime. Radio irregularity, channel fading and interference results in larger energy consumption and latency for packet transmission over wireless channel. Cooperative transmission of data using multi-input multi-output (MIMO) scheme is used to combat channel fading and improve the communication performance of distributed wireless systems. However, an inefficiently designed medium access control (MAC) protocol may diminish the performance gains of MIMO operation. Hence this paper develops a distributed MAC protocol for packet transmissions using fixed group size cooperative MIMO utilising space time trellis code (STTC) to achieve high energy savings and lesser delay. Further, to ensure the stability of transmission queue at the sender, this paper also proposes a threshold based MAC protocol for MIMO transmission. The protocol uses thresholding scheme that updates dynamically the cooperative group size based on the queue length at the sending node. The performance of the fixed group size MIMO MAC protocol using STTC technique is evaluated for various orders of diversity in terms of transmission error probability, energy consumption and delay. Simulation results are also provided to evaluate the performance of threshold based MAC protocol. Results show that 4X4 cooperative group size is dynamically selected as the cooperative group size as it provides minimum energy and delay. Cooperative transmission using STTC technique provides significant performance improvement than uncoded scheme due to the exploitation of MIMO diversity gain.

Keywords: Cooperative MIMO, diversity gain, energy efficiency, MAC, STTC, thresholding scheme, wireless sensor network

Title of the Paper: An Advance Wireless Multimedia Communication Application: Mobile Telemedicine


Authors: Chin-Feng Lin

Abstract: In this paper, we describe mobile telemedicine, which is an application in advanced wireless multimedia communication. Mobile telemedicine is one of the advanced technologies of the 21st century. It can be used to provide auxiliary medical service and has accordingly been used in emergency situations, mobile hospitals, personal healthcare, and in rapidly alerting doctors to patients’ disease, rehabilitation, etc. By exploiting the advantages of wireless multimedia communication, such as current high utility, convenience, high data transmission rates, high reliability, and wide coverage, we have developed a range mobile telemedicine systems. Mobile telemedicine technology is a wireless remote medical technology that incorporates a combination of biomedical engineering, electrical engineering, and computer science; the technology also includes various advanced medical services. It is a technology unconstrained by the limitations of time and space. Using this technology, family doctors can be more actively involved in the daily lives of their patients. There is no doubt that in the future, we will witness an era of ‘ubiquitous mobile telemedicine’. This technology is expected to bring about revolutionary changes in the fields of medicine and engineering. Such changes will be accompanied by ample opportunities for business, scope for the early diagnosis of diseases, and improvements in medical services. Moreover, manufacturers of clinical equipment are expected to respond favourably to these developments. Advanced technologies of the 20th century, such as the internet and mobile communication, have made human lives considerably easier. The combination of these two technologies has given rise to wireless multimedia networks, an extension of which is the mobile telemedicine systems. We would like to emphasize that the R&D process of these mobile telemedicine systems is similar to that of pharmaceuticals.

Keywords: Ubiquitous mobile telemedicine, advanced wireless multimedia communication, emergency situations, mobile hospitals, personal healthcare, patients’ disease, rehabilitation.

Title of the Paper: Secured Reactive Routing Protocol for Mobile Nodes in Sensor Networks


Authors: P. Samundiswary, P. Dananjayan

Abstract: Wireless sensor networks have drawn a lot of attention recently due to their broad applications in both military and civilian operations. Sensor nodes in the network are characterized by severely constrained energy resources and communicational capabilities. Since, these nodes are frequently established in a physically insecure environment, they are vulnerable to different types of active attacks. These attacks can inject malicious packets by compromising the node. Routing protocols are common target of these compromised nodes. Secured reactive routing protocols have recently been developed by using cryptographic algorithms against these attacks. However these routing protocols entail a number of prerequisites during both network establishment and operation phases .In contrast, trust based routing protocols locate trusted routes rather secure routes in the network. In this paper, a secure routing protocol named secured dynamic source routing protocol (S-DSR) is implemented for mobile sensor networks by incorporating trust based mechanism in the existing dynamic source routing protocol (DSR). Simulation results prove that S-DSR outperforms the DSR by reducing the routing overhead and improving the delivery ratio of the network.

Keywords: Wireless sensor networks, Malicious nodes, DSR protocol, Secured dynamic source routing protocol, Trust Model, Sinkhole attack

Title of the Paper: An Implementation of Designing Media Streaming System for Live Broadcast


Authors: Hsieh-Hua Yang, Jui-Chen Yu, Yeong-Diann Wang, Hung-Jen Yang, Hsueh-Chih Lin, Wei-Yuan Dzan

Abstract: In this study, we designed and constructed a live media streaming system to broadcast important activities such as: graduation ceremonies, sport games, and banquets. There are many different streaming systems and coding formats. In this study, the selecting procedure would be conducted to find suitable and stable technology for implementing live broadcast service, and evaluate the feasibility of system. This article had three parts, including of introductory the streaming technologies, designing and constructing the streaming system and implemented the streaming system.

Keywords: Design, broadcast, live, streaming system, feasibility

Issue 4, Volume 9, April 2010

Title of the Paper: Investigation of Foliage Effects via Remote Data Logging at 5.8 GHz


Authors: Pon Lai Ly, Phoon Lai Ly, Tharek Abd. Rahman, Mohammed Khomeini Abu

Abstract: This paper presents an unconventional methodology in examining the extent of vegetation blockage effects imposed on near line-of-sight (NLOS) fixed wireless links based on Institute of Electrical and Electronics Engineers (IEEE) 802.11a Wireless Local Area Network (WLAN) standard operating at frequency 5.8 GHz of Unlicensed National Information Infrastructure (UNII) band. By employing the concept of remote data logging, power received measurements were acquired constantly via a remote server for 24 hours and seven days a week from three dissimilar NLOS links within the campus of Universiti Teknologi Malaysia (UTM) in which it can best be described as suburban environment. These point-to-point links deployed in conjunction with wireless campus are impeded directly or indirectly by vegetation. The behaviour of these site-specific links performance is studied. The average excess path loss inclusive of foliage loss which is relevant to the climate of a tropical country is derived. Comparison of tabulated results between these divergent fixed wireless links besides exploratory data analysis is presented.

Keywords: Foliage, Path loss, Propagation, Fixed, Wireless, Near Line-of-sight

Title of the Paper: An Effective Cancellation Technique of Cochannel Interference Based on Multiuser Detection Scheme for MFSK/FH-SSMA Systems


Authors: Jyh-Horng Wen, Chuan-Wang Chang, Sheng-Fong Lin

Abstract: The performance of a multilevel frequency shift keying/frequency hopping-spread spectrum multiple access (MFSK/FH-SSMA) system over a cochannel interference scenario is dependent on multiuser detection schemes. Many investigations have demonstrated huge potential capacity and performance improvement by using multiuser detection schemes. However, their schemes are extremely complex while the total number of users is increased because the multiuser interference becomes larger. In this paper, we propose a novel multiuser detection scheme to reduce the complexity of decoding process. The performance of the system with the proposed scheme over a nonfading channel is simulated and compared with that of conventional and other multiuser interference cancellers. Simulation results show that the proposed scheme reduces the system complexity and improves the bit error rate (BER).

Keywords: Multilevel Frequency Shift Keying (MFSK), Frequency Hopping-Spread Spectrum Multiple Access (FH-SSMA)

Title of the Paper: Design of a Free Electron Maser without Wiggler


Authors: Fareq Malek, James Lucas, Yi Huang

Abstract: We are developing prototype free electron maser (FEM) that is compact, powerful and efficient for potential industrial applications. The design, set-up and results of a novel X-band rectangular waveguide pre-bunched free electron maser (PFEM) are presented in this paper. Our initial device operates at 10 GHz, without wiggler and employs two rectangular waveguide cavities (one for velocity modulation and the other for energy extraction). The electron beam used in this experiment is produced by thermionic electron gun which operates at 3 kV and up to 50 μA. The nominal beam diameter is 1mm passing across the X-band cavity resonators. The resonant cavity consists of a thin gap section of height 1.5mm which reduces the beam energy required for beam wave interaction. The results, progress so far and the scope of work for the next couple of months are reported.

Keywords: Pre-bunching, X-Band, Velocity modulation, Free Electron Maser, Rectangular waveguide

Title of the Paper: A Carrier Fragmentation Aware CSMA/ID MAC Protocol for IP over WDM Ring Networks


Authors: Jih-Hsin Ho

Abstract: In this paper, a packet pre-classification MAC protocol based on Carrier Sense Multiple Access with Idle Detection (CSMA/ID) with carrier fragmentation aware scheme has been investigated for completely transporting IP packets over the all-optical WDM ring networks. In order to improve the utilization of the network, the packets are first pre-classified into various class queues of access point (AP) according their length. The downstream access point recognizes the incomplete IP packet by the presence of the sub-carrier signal and pulls it off the ring. The carrier-sense can check the available channel length (ACL) to notify the transmission queues transmit the packet. This protocol avoids packet collision and uses carrier fragmentation when finding no appropriate ACL. An analytical model has had been developed to evaluate the performance of the protocol, and the simulation results show good network efficiency.

Keywords: CSMA/ID, Carrier fragmentation, Available channel length, Analytical model and simulation

Title of the Paper: Study on Power and Rate Control Algorithm for Cognitive Wireless Networks


Authors: Qian Hu, Zhenzhou Tang

Abstract: Rate control and power control are two important issues in cognitive radio networks. In this paper, three rate control strategies are first introduced, namely Dirty Paper Coding (DPC) strategy, Noise strategy, and Opportunistic Interference Cancellation (OIC) strategy. The achievable rates of the three strategies are also compared. Then, optimal power control algorithms are proposed, each corresponding to one rate control strategy. The algorithms achieve the maximum transmit rate for the cognitive user by appropriately controlling the transmit power on each subchannel under the interference temperature constraint of the primary user. Simulation results show that the proposed algorithms can dramatically improve the transmit rate of cognitive user.

Keywords: Cognitive radio, Interference temperature, Power control, Rate control

Issue 5, Volume 9, May 2010

Title of the Paper: A Secure and Efficient Protocol of Multiple Session Keys Generation


Authors: Chang-Kuo Yeh

Abstract: To negotiate a session key can benefit from the technique of the public-key cryptography such as key exchange and digital signature. This key cannot be used until the session is finished. In current model such as SSL, if the sender desires to re-establish another new session with the same receiver, the both sides, for security consideration, should repeat the same key exchange and digital signature processes to generate a new session key. Apparently, the two processes must lower the communication system efficiency. Therefore, a new session key generation protocol is proposed to overcome this demerit. In our new model, the key exchange and digital signature process only perform once, and the subsequent session keys can be computed in both sides without the two processes. Because the two processes can be eliminated, our protocol can promote more performance than the current-used model.

Keywords: Public-key cryptography, SSL, Authentication, Key Agreement

Title of the Paper: Implementation of WIMAX IEEE802.16d Baseband Transceiver on Multi-Core Software-Defined Radio Platform


Authors: Mohammed Aboud Kadhim, Widad Ismail

Abstract: IEEE 802.16d was developed for WIMAX wireless communication, which is based on orthogonal frequency division multiplexing (OFDM) technology, to enable advancement towards 4G The last decade have seen growing importance place on research in wireless communication system. A recent surge of research on WIMAX has given us opportunities and challenges. In this paper, we describe the implementation of WIMAX baseband transceiver on multi-core Software-defined radio (SDR) platform. This work presents a new approach to the adaptation of WIMAX technology on the basis of SFF SDR development platform. The proposed WIMAX system was modelled-tested, and its performance was found to comply with Stanford University Interim (SUI) Channel Models that have been elected for the wireless channel in the simulation process. The performance results of the simulated on different modulation systems were also compared among themselves.

Keywords: WIMAX, SFF SDR, OFDM, RS, Coding, SUI, AWGN

Title of the Paper: Capability-Aware Object Management based on Skip List in Large-Scale Heterogeneous P2P Networks


Authors: Takashi Tomimoto, Takuji Tachibana, Kenji Sugimoto

Abstract: In this paper, we propose an object management method in large-scale heterogeneous P2P networks. In the proposed method, objects can be stored in and searched from nodes by considering node's capabilities. The proposed system is based on skip list, and two identifications are utilized; TypeID and HashID. The TypeID is used to specify each node's capabilities, on the other hand, HashID is used for providing load balancing among nodes with similar capabilities. According to the two identifications, message routing for storing and searching objects is performed. We evaluate the performance of the proposed method by simulation, and we investigate the effectiveness of the method. Numerical examples show that the proposed method can manage objects based on node's capabilities and can provide the scalability when the number of nodes is large and the difference in node's capabilities is large.

Keywords: Peer-to-Peer networks, Skip list, DHT, Heterogeneous networks, Object management

Title of the Paper: Evaluation of Restoration Mechanisms for Future Services using Carrier Ethernet


Authors: H. Wessing, M. Berger, H. M. Gestsson, H. Yu, A. Rasmussen, L. Brewka, S. Ruepp

Abstract: In this paper, we evaluate and classify future service according to their requirements for delay, loss and bandwidth. The most demanding services include IPTV in different forms, hence IPTV is used as a representative for future services. Carrier Ethernet technologies are introduced with special focus on its OAMfunctionalities, and it is evaluated how IPTV performs in case of link failures on a Carrier Ethernet implementation. It is concluded that OAM update times of 10 ms is required to provide acceptable restoration performance in case of errors.

Keywords: Carrier Ethernet, IPTV, MDI, PBT, MPLS-TE

Title of the Paper: On Performance of TCP and VoIP Traffic in Mobile WiMAX Networks


Authors: Dragorad Milovanovic, Zoran Bojkovic

Abstract: The major performance objectives of the next-generation wireless communication systems are high link capacity and increase application/service performance from the user perspective. An attractive technology for providing broadband access is WiMAX network. For the network and application-level capacity and performance analysis, we first provide an overview of WiMAX network architecture and system performance. Afterward we discuss the benefits and challenges of flat architecture for mobile networks. In this kind of architecture the access service network gateway and base stations are consolidated into a single channel. All-IP flat architecture is a promising option. However, performance goals of the WiMAX system are conflicting: maintenance VoIP quality vs. completely utilization of the remaining capacity for TCP. We investigate the approaches in performance optimization based on TCP modification schemes. The solution is to control TCP traffic before entering WiMAX network in conjunction with methods to dynamically estimate available bandwidth in real time.

Keywords: Wireless networking, TCP performance, Traffic control

Issue 6, Volume 9, June 2010

Title of the Paper: A Mobile Disaster Management System Using the Android Technology


Authors: Jovilyn Therese B. Fajardo, Carlos M. Oppus

Abstract: The Philippines is one of the countries in the world vulnerable to natural hazards because of its geographic location. It also lacks an efficient disaster management system that will help in times of need. One common scenario during disasters is that the activity of rescue and relief is not well-coordinated. For this reason, there is a need for a system that will help in the efficient provision of rescue and relief to disaster-affected areas. Since the use of smart phones is gaining interest in people, the disaster management system was implemented as a smart phone application using Google’s Android operating system. The disaster management system Android application known as MyDisasterDroid determines the optimum route along different geographical locations that the volunteers and rescuers need to take in order to serve the most number of people and provide maximum coverage of the area in the shortest possible time. Genetic algorithm was applied for optimization and different parameters were varied to determine the most optimum route.

Keywords: Android, Disaster management, Genetic algorithm, Travelling salesman problem, Smart phone application, Wireless mobile technology

Title of the Paper: An Optimum Design of 3x3 Optical Switch based on Integrated MZI, Including the Influence of Electro Optic


Authors: Mohammad Syuhaimi Ab. Rahman, Khaled Mohamed Shaktur, Rahmah Mohammad

Abstract: The influence of waveguide thickness on the output power according to the voltage applied to the electrodes based on Integrated Mach-Zehnder interferometer is investigated. Simulation result which are performed using BPM software, stress that there is an optimum value of 3x3 switching optical waveguide thickness at which the switch process and in turn the output power at 1300nm wavelength can be achieved. This is because the thickness affect significantly the coupling region between the waveguide, and also the effect of the Pockels and Kerr coefficients.

Keywords: MZI (Mach-Zehnder interferometer), Electro-optics, Directional couplers, Kerr and Pockles coefficients, All-optical switch

Title of the Paper: High Level Tele-Operating Speech Communication System for Controlling a Colony of Robots


Authors: Al-Dahoud Ali, Mohamed Fezari, Attoui Hamza

Abstract: The purpose of this article is to presents the implementation and design of a high level communication interface based on multi agents model for a set of autonomous robots. Classical techniques, used in speech recognition which are zero crossing and extremes, dynamic time warping and different features such as Mel frequency Cepstral coefficients, delta MFCC , Energy and LPC are merged in order to increase the rate of recognition, followed by a decision system based on independent methods test results, are used as a speech recognition agent. Two consecutive agents; namely syntactic and semantic agents, are added to improve the recognition rate and improve the human-machine communication language. To implement the approach for tele-operating a set of robots on a real time, a Personal Computer interface was designed based on Bluetooth wireless communication modules to control the movement of a set of robots using high level language. The voice command system for four autonomous robots is designed however the robot navigation techniques are not discussed in this work. The main parts of the robots are based on a microcontroller from Microchip PIC18F2450, a set of sensors modules and a Bluetooth module.

Keywords: Speech recognition, HLL (High Level Language, Hybrid methods, human -robot interaction, DTW, Robots, Microcontroller, wireless communication

Title of the Paper: Curved Strip Dipole Antenna on EBG Reflector Plane for RFID Applications


Authors: N. Fhafhiem, P. Krachodnok, R. Wongsan

Abstract: This paper presented the study and design the curved strip dipole on Electromagnetic Band Gap (EBG) reflector plane that can be affected the performance of the proposed antenna for RFID application. The proposed antenna consists of a strip dipole that constructed of a metallic sheet and it was bended to be a half of annular with feed point at the center for yielding wider beamwidth. Normally, a curved strip dipole antenna without the reflector provides low gain of 1.5 dB, due to its features of radiation patterns, both in azimuth and elevation planes. In our case, the resonant EBG technology has been used to be a reflector for directive gain increment by utilizing the good performances of EBG structure, which is capable of providing a constructive image current within a certain frequency band. Therefore, when this curved dipole is appropriated located horizontally on a resonant EBG reflector, the low profile antenna that provides good performance such as large beamwidth, wide bandwidth, and high directive gain can be obtained, consequently. The first curved strip dipole antenna with 3?3 elements and the second one with 5?5 elements of EBG reflectors, respectively, have been fabricated and their RF performances have been measured. For 3?3 elements of EBG reflector, the measured beamwidth in E- and H-planes are 100° and 110°, respectively, frequency bandwidth is 2.06-2.59 GHz and directive gain is 7.45 dBi at 2.45 GHz. In case of 5?5 elements of EBG reflector, the measured beamwidth in E- and H-planes are 65° and 120°, respectively, frequency bandwidth is 2.06-2.62 GHz and directive gain is 7.65 dBi at 2.45 GHz. From simulation and experimental results, it's obvious that many applications can be conceived for a curved strip dipole on EBG reflector plane due to its geometrical and electromagnetic features.

Keywords: Curved Strip Dipole Antenna, Electromagnetic Band Gap (EBG), RFID Technology

Title of the Paper: Performance Analysis of 1x2 Optical Power Splitter


Authors: Mohammad Syuhaimi Ab-Rahman, Foze Saleh Ater, Kasmiran Jumari, Rahmah Mohammad

Abstract: In this paper, the influence of the width of waveguide and the branching angle of the output arms on the output power of 1?2 optical splitter has been investigated in details. We showed that the output power is improved when the width increases for single mode transmission. In addition, at specified values the core and cladding refractive indices, approximately 50% input-to output power ratio is achieved at the output. Moreover, the output power can be controlled by adjusting the branching angle of the device.

Keywords: Banching angle, optical power, optical splitter, waveguide width

Issue 7, Volume 9, July 2010

Title of the Paper: Implementation of Zigbee-based and ISM-based Wireless Sensor and Actuator Network with Throughput, Power and Cost Comparisons


Authors: Rosula S. J. Reyes, Jose Claro Monje, Marc Ericson C. Santos, Lorlynn A. Mateo, Roma Lynne G. Espiritu, John Vianney Isiderio, Carlos Miguel M. Lacson, Ray Edwin T. Ocfemia

Abstract: Wireless sensor and actuator networks have expanding applications which requires better throughput, power efficiency and cost effectiveness. This study intends to contribute to the growing pool of knowledge on WSAN especially in the design for novel applications such as image or video over WSANs, and solar energy and RF energy harvesting for the WSAN nodes. Two basic scalable wireless sensor and actuator networks were implemented and characterized in terms of throughput and power consumption. The two WSANs are the Zigbee-based WSAN which is based on the IEEE 802.15.4 protocol, and the ISM-based Zigbee which makes use of the industrial, scientific and medical (ISM) radio bands. The star topology was used for both WSAN implementations. The throughput is quantified with varied factors including distance from node to node, obstructions in between nodes and co-channel interference. As distance and obstructions between nodes are increased, the throughput for both networks decreases with varying degrees. Co-channel interference is also considered. The ISM-based WSAN network is weak in dealing with co-channel interference and error rate as compared to the Zigbee-based WSAN, thus requiring it to have a better data encryption. Power consumption is generally larger for the ISM-based WSAN as compared to its Zigbee-based counterpart. However, the ISM-based nodes consume the same power even up to a few hundreds of meters distance and are thus practical for covering large distances. Therefore, the Zigbee-based WSAN system is more appropriate for closed environment, such as in room automation and home automation applications where distance from node to node is relatively shorter. The ISM-based WSAN prototype, on the other hand, can be developed further for applications in larger areas such as deployment in fields and cities, since transmission is not generally limited by distance and obstructions.

Keywords: Sensor, actuator, WSAN, Wireless Sensor and Actuator Network, power consumption, throughput

Title of the Paper: Quantifying Cryptographic Techniques in Radio Frequency Identification Protocols and Ways of Remedying the Security Threats


Authors: Cristina Hurjui, Stefan Holban, Adrian Graur

Abstract: Critical examinations concerning the Radio Frequency Identification security and privacy have determined wide analysis over the time. RFID applications have always assumed two important hierarchies: structures aiming to offer security to RFID systems and structures aiming to offer functionality, with no security issues. A way of creating radio frequency identification systems more secure relies on cryptography. Nine RFID protocols of identification and authentication are examined in this paper, so as to analyze the strong points and to find solutions for the weak or jeopardizing points that threaten the security and privacy of RFID systems. By reaching the best security and privacy solutions, using of RFID systems will bring visibility within developing business strategies or logistics processes, in thoroughly transparency. In many situations, the threatening over RFID structures is the result of designing weak protocols. Presumable attacks on RFID structures are evaluated; important ways of comparison and analysis amongst nine existing protocols are utlined. At the end of each description, solutions of treating the weak points are emphasized.

Keywords: Radio frequency identification, protocol of identification, protocol of authentication, security, privacy

Title of the Paper: Blind Signal Processing based on Information Theoretic Learning with Kernel-size Modification for Impulsive Noise Channel Equalization


Authors: Namyong Kim

Abstract: This paper presents a new performance enhancement method of information-theoretic learning (ITL) based blind equalizer algorithms for ISI communication channel environments with a mixture of AWGN and impulsive noise. The Gaussian kernel of Euclidian distance (ED) minimizing blind algorithm using a set of evenly generated symbols has the net effect of reducing the contribution of samples that are far away from the mean value of the error distribution. The process of ED minimization between desired probability density function (PDF) and output PDF is considered as a harmonious force interaction on PDF shaping between concentrating force and spreading force. The spreading force is composed of the difference between output sample values themselves, and is directly related with the output information potential and the output entropy that leads to the output distribution spreading out. The proposed kernel-size modification scheme is to impose loose discipline on the spreading force by employing larger kernel-size so that the long distance between two outputs which are correct symbol-related and far-located is less likely to be treated as impulsive noise. From the simulation results, the proposed kernel-size modified blind algorithm not only outperforms correntropy blind algorithm, but also significantly enhance robustness against impulsive noise.

Keywords: Impulsive noise, blind equalization, kernel-size modification, source symbol assignment, information-theoretic learning, PDF, correntropy, CMA

Title of the Paper: A Solution for Secure SIP Conferencing over IMS and SAE


Authors: Cristina-Elena Vintila

Abstract: Over the latest few years, most of the major telephony and services providers have got their attention on the LTE/SAE solution, in the attempt of getting the most bandwidth and features at the least implementation and operating price. One of the major challenges that 3GPP, the creator of LTE/SAE architecture, has faced is the IMS integration with SAE. The latest standard version available at this moment on IMS integration and its security challenges is TS 33.203, which is focused on 3G security aspects. When talking about IMSSIP security, there are several studies that propose end-to-end security for a SIP conversation over EPS infrastructure. This paper reviews the security issues that resides in the SAE-IMS interaction and, looking at the specificities of the SIP conferencing, proposes a security model that uses GDOI management to secure the SIP conference data over IMS and SAE. One important aspect of conferencing in the mobile world is to realize the user is never stationary. One chapter of this paper describes the most complicated type of mobility scenario and also introduces the role of the Diameter server into this architecture.

Keywords: SAE, LTE, EPS, EPC, IMS, security, SIP, conference, GDOI, GCKS, IPsec, key management

Title of the Paper: Analysis of Routing Metrics for Offering IPTV over WiMAX Using Fuzzy Logic


Authors: Arianit Maraj, Skender Rugova

Abstract: The quality of delivering IPTV services depends on the network QoS and bandwidth of broadband service providers. The possibility to offer high bandwidth capacity of WiMAX technology is attractive to offer IPTV services. There is an increasing trend to deploy WiMAX technology for offering those services. Network QoS for offering IPTV services depends on network efficiency. To satisfy QoS requirements for offering IPTV over WiMAX technology we should take into consideration routing metrics that affect directly to the QoS. Here we will consider three metrics: bandwidth, losses and delays. For transmitting multimedia (in this case IPTV) services over WiMAX it is desired to design some controlling mechanisms for solving different problems in a network in case of packet delays, losses etc. Because of complex nature of controlling mechanisms it is desired to design intelligent controlling techniques. One of the intelligent techniques that would be present in this paper is fuzzy logic controller. In this paper we will design FLC using Matlab software. As input parameters will be three routing metrics mentioned above, whereas as output parameter will be network efficiency. The aim is to obtain better values of network efficiency using different rules from Rule Editor and using appropriate defuzzification method.

Keywords: Routing Metrics, Quality of Service, WiMAX, IPTV, Fuzzy Logic, Defuzzification Method

Issue 8, Volume 9, August 2010

Title of the Paper: Performance Comparison of Wavelet Packet Transform (WPT) and FFT-OFDM System Based on QAM Modulation Parameters in Fading Channels


Authors: Haitham J. Taha, M. F. M. Salleh

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) has been widely adopted in many applications due to its good spectral performance and low sensitivity to impulse noise and multipath channels. It has been widely adopted and standardized in many applications today. It is well known in OFDM that a cyclic prefix (CP) is appended to each symbol in order to mitigate the effect of Inter-Symbol-Interference (ISI). However, this reduces the spectral efficiency. A perfect reconstruction using wavelet packet transmultiplexer in OFDM transceiver counters the degrading effect of ISI, and also conserves bandwidth. In comparison to FFT-OFDM, Wavelet Packet Modulation (WPM) offers much lower side lobes in the transmitted signal, which reduces inter carrier interference (ICI) and narrowband interference (NBI). WPM improves spectral efficiency due to the exclusion of CP. Nevertheless, it requires an efficient equalization technique to counter the ISI and ICI. Wavelet based OFDM has been suggested to improve BER performance of transceiver in wireless communication. In this paper, a study of wavelet packet transform modulation WPT-OFDM scheme is conducted, and the performance comparison is made against the traditional FFT-OFDM over various fading channels. The analysis is done using various number of modulation QAM constellation points. Specifically, the analysis is on the effect of QAM constellation points in AWGN channel, flat fading channel and frequency selective fading channels. Simulation results using QAM Modulation points (8 to 64 Point), and the BER best performance of WPT- OFDM system is when the QAM Modulation parameter (QAM = 8) in all channels.

Keywords: FFT-OFDM, Wavelet Packet, WPT-OFDM

Title of the Paper: Selection Based Successive Interference Cancellation for Multicode Multicarrier CDMA Transceiver


Authors: S. Praveen Chakkravarthy, N. Nagarajan, V. Arthi

Abstract: A Selection based Interference algorithm for efficient decoding of MC-MC-DS-CDMA Transceiver with Multipath Rayleigh fading is presented in this paper.The Interference Cancellation algorithm is capable of increasing signal strength and reducing probability of error using two stages of decoding namely , Selection phase and Threshold decoding phase .The numerical results have shown that effective decoding with respect to frequency increases SNR levels.

Keywords: MC –MC DS CDMA (Multicode Multicarrier Direct Sequence CDMA),SIC(Succesive Interference Cancellation) SNR(Signal to Noise Ratio)

Title of the Paper: Dissolving Active Networks Privacy Threats and Vulnerabilities


Authors: Tai-Hoon Kim

Abstract: This paper proposes an efficient dual authentication key exchanged in an active network scenario. The scheme protects personal privacy of identity information. It also provides an effective method to protect against DOS attacks with the scope information of initiator’s random number table sent by the responder.

Keywords: Active Networks, Security, Identity Management System

Title of the Paper: Accounting Professional Education Schemes: Case of Czech Republic and Estonia


Authors: Jiri Strouhal, Kaidi Kallaste

Abstract: The knowledge level of professional accountants is emerging issue in each economy. Change of economic environment in Central and Eastern Europe in 90s of 20th century brought new requirements on professional accountants. This paper provides the comparative analysis between accounting certification schemes in the Czech Republic and Estonia (two emergent countries from the area of CEE), which are applied on professional accountants. Those schemes are also compared to international referential (qualifications ACCA, CPA Australia and AIA). The results show very high level of convergence between Czech model and international qualification schemes.

Keywords: Accounting Certification; International Education Standards; Association Coefficients; Professional Accountants; Czech Republic; Estonia

Title of the Paper: Linear Model of Adapting Frame Size in DFSA of Passive GEN2 RFID Systems


Authors: Petar Solic, Josko Radic, Nikola Rozic, Mladen Russo

Abstract: Low costs of passive UHF RFID tags, as well as their simplicity makes them appropriate for the localization and tracking services in today’s fast-moving, information rich trading networks. However, a few disadvantages of passive RFID technology performances, as a reading range of passive tags and high collision rate during RFID reader-tag communication, still needs quality of service improvements. In order to maintain passive technology cheap, but to improve the disadvantages, it is important for tags not to include any additional electronic circuitry, and to maximize the efficiency of the actual hardware. So, it is necessary to develop the optimal algorithms in order to maximize the communication efficiency. In this paper we provide the analysis on MAC layer protocol of passive UHF-Gen 2 RFID standard. In the accordance with the standard, we provide the improvement for the frame size adaptation, which increases the throughput of RFID system and thus minimizes the time for tags identification. The algorithm for the improvement includes the estimate of the number of tags through the linear behavior model of number of Collisions (C), and Successful (S) slots within the frame. Estimated number of tags is used for adaptation of the frame size. For comparison, simulation results show that our approach provides better efficiency than Q-Selection algorithm from UHF-Class1-Gen 2 standard.

Keywords: Framed Slotted ALOHA, transmission control strategy, Q-selection Algorithm, RFID identification, Number of tags estimation

Title of the Paper: Semantic Concordance in the South-East European Languages


Authors: Ancuta Negrea, Agnes Erich, Zlate Stefania

Abstract: The common terms of the south-east European languages that present semantic convergences [1], belong to a less explored domain, that of comparative linguistics. “The reason why the words have certain significations and not others is not found in the linguistic system or in the human biological or mental structures … it is the societies that, through their diverse history, determine the significations, and the semantics is found at the crossroads between the historical complexity of the reality it studies and the historical complexity of the culture reflecting on this reality… its object is the result and the condition of the historical character, thanks to the relations of mutual conditioning that relate the signification to the historic events of each human community.”[2] In the south-east European languages, several onomasiological lexical fields have been delimited, in which we can discover tendencies of parallel semantic development for several terms of different origin. The terminology of the wedding can be analyzed from this perspective. In the case of the south-east European languages, the parallel semantic tendencies are present as: development of identical meanings by different words in different languages, naming the same reality; borrowings in several languages of the same meanings of a polysemantic word. In classical Latin, there was a strict opposition according to gender for the verbs denominating marriage, homo uxorem ducit being the counterpart of femina nubet . During the postclassical period, in a sermon of Saint Augustine, instead of these verbs appear uxorati viri and maritare feminae. This old opposition according to gender has been kept in Romanian, in the southern Italian dialects, in Provencal, Catalan and certainly in Dalmatian. In other areas of the Roman Empire, this opposition according to gender has been lost because of the influence of the German languages, so that the same verb is used for both genders. In this sense, it would be interesting to follow the evolution of the French verb marier, attested for the first time in 1155 with the meaning “to marry one’s daughter”, After 1170, the reflexive construction se marier avec “to take for wife” emerges, instead of the transitive verb marier (attested for the first time in 1176), a construction still encountered in some provinces. Se marier, with a subject in the plural, is attested in the year 1220 (DILF 2, 1192; NDEI, 446; Paris, 1971). Yet, in other Romance languages, for instance in Italian, though there is the construction maritarsi – in which the opposition according to gender is neutralized, there is also the verb ammogliarsi “to take a wife”, which is used only from the man’s point of view, including the form moglie “woman, wife”.

Keywords: Balkan linguistics, terminology of the word “house”: Bg. kasta, Srb., Cr. kuca, Maced. kuk’a, slov. koca, Rom. casa; Ngr. σπητη; Alb. shtepi ; the terminology of “wedding”: wedding, sister-in-law, brother-in-law

Title of the Paper: Robot Vision and Video Transmission


Authors: A. Ritchie, J. Conradi, A. Prevot, E. A. Yfantis

Abstract: In this research paper we examine the problem of distance resolution using four cameras and a noninvasive laser light for robot vision. The cameras are placed in a cross configuration and the noninvasive laser is in the center of the cross. The system constitutes the vision part of a robot used for remote patient visits by physicians. The system enables physicians to perform between visit comparisons in order to assess health patient improvements. During the patient’s hospital robot visits made with the help of a nurse, the cameras take the relevant patient images and transmit them wirelessly to a file server housed in the hospital where they are stored and from where they are also being transmitted to the Phycisian’s office for real time examination, and comparison with the images of the previous visit. The ROY is compressed lossless and the remaining part of the image is compressed lossy. Each time the robot visits a patient positions itself on a fixed distance from the center of the ROY. Therefore distance resolution and distance tolerance interval estimation is very important. In this research paper we model the distance with a Gamma probability distribution and we compute the tolerance interval of the distance. Our system is part of a sophisticated system that includes personal patient networks, and radiological image – video management, and secure network transmission.

Keywords: Network programming, De-Interlacing, Compression, RAID Arrays, Client, Server, Real-Time

Issue 9, Volume 9, September 2010

Title of the Paper: VHDL Modules and Circuits for Underwater Optical Wireless Communication Systems


Authors: Davide Anguita, Davide Brizzolara, Giancarlo Parodi

Abstract: Underwater wireless optical communication has been used for establish a link between mobile vehicles and/or fixed nodes because light, especially in the blue/green region, allows to achieve higher data-rate than acoustical or electromagnetic waves for moderate distances. The here proposed work has the aim to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network of dense-deployed fixed nodes for specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. In particular, taking into account already developed protocols for optical wireless communication, the focus is on the hardware implementation of different flexible modules to support both point-to-point and directional communication targeting the use of these technologies in the field of UnderwaterWireless Sensor Network and the integration with current terrestrial technologies forWireless Sensor Network. After a careful analysis of benefits and problems related to optical transmission underwater, design considerations are proposed with the description of the implemented modules. The use of light impulse for communication is motivated by the possibility of targeting high data-rate, low-cost and small dimension components. This paper describes an overall vision of the system: a HDL implementation of flexible modules for the management of optical communication (based on IEEE 802.15.4 and IEEE 802.11 standard) which target the interface with current terrestrial technology forWireless Sensor Networks; the design and implementation of circuits for underwater optical point-to-point and planar communication. The preliminary results and design consideration are reported considering also future possible developments.

Keywords: Underwater Wireless Communication, Optical Communication, Physical (PHY) Layer, Medium Access Control (MAC) Layer, Wireless Sensor Networks

Title of the Paper: Integration of Real Network Components into OPNET Modeler Co-simulation Process


Authors: Milan Bartl, Jiri Hosek, Tomas Matocha, Karol Molnar, Lukas Rucka

Abstract: The OPNET Modeler is a simulation environment enables modeling of large-scale networks with in detail defined parameters. This paper is focused on the possibility to communicate with external systems and applications that this environment offers. Due to this we are able to interconnect simulation environment with real network system and gain the simulation results more accurate and in accordance with the reality. We created communication model composed from network scenario created in the OPNET Modeler, C/C++ external application and Cisco router. For this purpose we implemented the SNMP protocol into the OPNET Modeler. This model enables data exchange between external network component and work station in OPNET Modeler scenario. This model is very useful especially in the situation when you need to include a real network device into simulation process, because the pure simulation environment is not quite sufficient.

Keywords: BER, Esys interface, MIB, OPNET Modeler, SNMP

Title of the Paper: Algorithms of Digital Modulation Classification and their Verification


Authors: Anna Kubankova, David Kubanek

Abstract: Two methods of the classification of digital modulations ASK, FSK2, FSK4, MSK, BPSK, QPSK, 8PSK and QAM-16 are presented. The first algorithm is based on module and phase spectrogram analysis. Here it is very important to estimate the symbol length of the received signal and thus we introduce two methods for this purpose. They are based on the wavelet transform and cepstrum analysis. The second algorithm of modulation classification uses instantaneous values of signal (instantaneous amplitude, phase and frequency). A method of the practical verification of classification algorithms in laboratory environment is described.

Keywords: Classification of modulations, examination, modulation, symbol length estimation

Title of the Paper: QoS Parametric Correlation for Network Management, a Link between Application's Requests and Network's Capabilities


Authors: Emanuel Puschita, Tudor Palade, Mihai Sarlea, Ancuta Moldovan, Rebeca Colda, Irina Vermesan

Abstract: Optimal resources management between application’s requests and network’s capability is determined by a human-device interaction, completing in this way the future architectural concept of developing inherent / integrated resource management capabilities inside the network elements. By aggregating and setting up QoS parametric dependencies between user’s needs and network’s context, resource management represents the guarantee for high performance network. Performing an analysis of application inter-frame delay and frame-size parameters – as the application’s requested parameters – upon the received signal level, retries rate, channel throughput, and loss rate of the RF network – as the network’s capabilities – the paper demonstrates that QoS parametric correlation can prove crucial on network resource management.

Keywords: QoS parameters, network management, frame-size, inter-frame delay, received signal level, retry rate, channel throughput, loss rate

Title of the Paper: Identifying the Course Role of In-service Learning via the Social Network Structure


Authors: Lung-Hsing Kuo, Hsieh-Hua Yang, Jui-Chen Yu, Hung-Jen Yang, Lydia Lin

Abstract: The purpose of this study focused on the social network structure of in-service development for the English literature expertise teachers in Taiwan High school. Social network analysis methods include the core measures, identification of groups to analyze the role, figure based on the statistical analysis and so on. In this study we use 2009 National Teacher in-service Education Information Network ( database to obtain 4,317 sample resources. The expected result should be able to understand English literature teacher in-service refresher training expertise in the overall network of centricity, teachers participate in studies course subject categories and countries connected, education seminar for subgroups generated number, subgroups on overall network impact, etc.

Keywords: In-service development, Social network structure, High school, UCINET, English literature teacher

Title of the Paper: Perceived Organizational Culture, Professional Commitment, Advice Network and Job Satisfaction of Novice Nurses


Authors: Hsieh-Hua Yang, Fen Fen Huang, Yi-Horng Lai, Chi-Jen Hsieh, Yu-Sheng Liao, Wan-Ching Chao, Shu-Fen Chen

Abstract: Nurses’ job satisfaction is an important issue and it receives a lot of attention in the international nursing literature. But research about the influencing factors of novice nurses’ job satisfaction is yet insufficient, especially a newcomer’s advice network. This study explored the influence of network outdegree in the same division and across divisions on job satisfaction, as professional commitment, and perceived organizational culture were included as control variables. A total population of nurses recruited within 3 months in a medical center was surveyed. The results showed that perceived organizational culture was the strongest predictor of job satisfaction; and support the different effects of advice network outdegree in the same division and across divisions on job satisfaction.

Keywords: Social network; advice network, outdegree across divisions; job satisfaction; novice nurse

Title of the Paper: Investigating the Impacts of Digital Elements in Web Information for Socio-Informatics


Authors: Siti Z.Z. Abidin, Nasiroh Omar, Hani F. A. Rahman, Marshima M. Rosli

Abstract: The Web offers enormous amount of digital information for communication and socializing. The fact that Web has been able to provide users with instant and global access to shared information, this platform gives a powerful medium of communication. When people are free to send and receive information, there is a potential to influent other people or be influenced by others through the use of digital element for its effective presentation. In today’s world, there are many cases where people take advantage of these social media to involve in activities that lead to crime cases. Information can be manipulated. Therefore, it is crucial to identify the impact of digital element within the Web information that affects users’ minds. In web-based socio-informatics, the conversation of these people take place without any support of physical movement like in face-to-face environment, hence, the strength of digital elements appear to be effective in influencing people’s perception. In this paper, we discuss our study on investigating the impacts of digital elements that include text, two dimensional (2-D) and three dimensional (3-D) graphics, audio and video, which are embedded in Web information. For finding such factors, each type of digital elements is examined in terms of its attributes and usage. Investigations are performed to look into the strength of such digital elements by understanding the existing guidelines, psychological or mental models and theories. It is important to look into such models and theories to justify how digital presentation can relate to the human perception. By identifying the impact factors, information can be constructed using the effective digital elements so that the social media are used in a proper manner with good impacts in strategic communication.

Keywords: Web information, impact factors, digital elements, socio-informatics, strategic communication, perception

Issue 10, Volume 9, October 2010

Title of the Paper: System Performance Evaluation of the IEEE 802.16e Pico-Base Station in Multihop-Relay and Mesh Networks


Authors: Kemal Alic, Ales Svigelj, Tomaz Javornik

Abstract: Paper proposes a new design and a simulation model for the pico base station based on IEEE 802.16e standard and evaluates its performance in a mutihop-relay and mesh networks. The proposed base station design allows multihoprelay communications and thus opens a possibility for the proposed base station to be an element of mesh networks. The conventional IEEE 802.16e base stations interconnected vie router or Ethernet switch are applied for point to point links and broadband wireless access. The design has been evaluated using proposed simulation model and the simulation tool OPNET Modeler for different scenarios that present real case deployment options for mesh networks thus allowing the multihop relaying that is to be supported only in the upcoming 802.16j standard, while the design is based on existing and well tested building blocks for conventional IEEE 802.16e base station.

Keywords: WiMAX, IEEE 802.16j, IEEE 802.16e, Pico base station, Simulation model, OPNET

Title of the Paper: Operating Room Information Systems Adoption by Portuguese Clinical Users


Authors: M. F. Santos, L. Gomes

Abstract: This research aims to assess the impact of the adoption of Information Systems by clinical users in the Operating Room. This is an empirical and qualitative research, to find a complete and comprehensive understanding of the phenomenon under study. A sample of Portuguese Anesthesiologist have been invited from public and private hospitals. Through the application of the Delphi method, with surveys online it is expected an interactive and systematical approach to estimate the impact of the adoption of these systems, based on the experience of several independent clinical users (experts).

Keywords: Clinical Information Systems, Delphi Methodology, Operating Room, Technology Acceptance

Title of the Paper: Services for Advanced Communication Networks


Authors: Vladislav Skorpil, David Novak

Abstract: Services for Advanced Communication Networks are described in this paper. An Artificial Neural Network will be used for the control of Network Elements, in our case a Switch. Classical sequence data processing is substituted by parallel processing. The classical switch and the switch controlled by a Kohenen Artificial Neural Network are compared. The switch has four ports and its own Quality of Service (QoS) control. Services such as FTP, HTTP, VoIP and QoS mechanisms without QoS, Best Effort QoS, FIFO QoS, Integrated Services (IntServ) and Differentiated Services (DiffServ) are simulated and compared. The level of priority contains the overhead of IP packet as the Type of Service (ToS) or also as Differentiated Services Code Point (DSCP). The Opnet Modeler programme is used for the simulation.

Keywords: Artificial Neural Network, ANN, Network Element, NE, Converged Network, Delay, Jitter

Title of the Paper: Radio Coverage Calculations of Terrestrial Wireless Networks using an Open-Source GRASS System


Authors: Andrej Hrovat, Igor Ozimek, Andrej Vilhar, Tine Celcer, Iztok Saje, Tomaz Javornik

Abstract: Radio network planning and dimensioning have significant impact on the overall system capacity of the cellular communication systems. Various commercial network planning and dimensioning tools with different radio signal propagation models implemented are available on the market. Their price and especially inflexibility led us to look for an open-source solution. The present paper describes usage of the open-source Geographical Resources Analysis Support System (GRASS) for the radio signal coverage calculation. GRASS modules calculating radio coverage prediction for a number of different radio channel models were developed which, together with module considering antenna radiation pattern influence, compute radio signal coverage for a defined cell. The complete network coverage is computed with modules for generating a data base table (e.g. MySQL, PostgreSQL), arranging the values in increasing order and determining maximal received power at each receive location. Additional modules for adapting input data and analyzing simulation results were also developed. The radio coverage tool accuracy was evaluated by comparing with results obtained from a dedicated professional prediction tool as well as with measurement results.

Keywords: Ntwork planning tool, open-source, GRASS GIS, path loss, raster, clutter, radio signal coverage

Title of the Paper: Knowledge Services in Business Process Management: A New Way for Increasing of Productivity?


Authors: Zuzana Tuckova, David Tucek

Abstract: This paper represent the appropriate software support for Process Management, and those tools which are used in a whole range of Czech and world-class manufacturing production and non-manufacturing enterprises as well as in organizations and other public sector administration institutions. The innovation in the tuition process lies in the fact that this software is not used for modelling the processes within the university (the organization itself) – but rather, that the students themselves model and analyze processes drawn from realworld praxis (working practices) in manufacturing production and non-manufacturing enterprises.

Keywords: ARIS (Architecture of Integrated Information Systems), Business Process Management, Education, FTE, Knowledge, Management

Title of the Paper: Ant Colony Inspired Self-Optimized Routing Protocol based on Cross Layer Architecture for Wireless Sensor Networks


Authors: Kashif Saleem, Norsheila Fisal, M. Ariff Baharudin, Adel Ali Ahmed, Sharifah Hafizah, Sharifah Kamilah

Abstract: Nowadays, wireless sensor networks (WSNs) are becoming increasingly beneficial, worthwhile and a challenging research area. The advancements in WSN enable a wide range of environmental monitoring and object tracking applications. Moreover, multihop (node by node) routing in WSN is affected by new devices constantly entering or leaving the network. Therefore, nature inspired self-maintained protocols are required to tackle the problems arising in WSN. We proposed ant colony stimulated routing, which shows an outstanding performance for WSNs. In this manuscript, a cross layer design based self-optimized (ACO) routing protocol for WSN and the results are presented. Link quality, energy level and velocity parameters are used to discover an optimal route. The signal strength, remaining power and timestamp metrics are trade in from physical layer to network layer. The emitted decision through the WSN discovery will establish the optimal route from source to destination. The adopted cross layer architecture helps ACO in improving the overall data delivery ratio; especially in the case of real time traffic.

Keywords: Ant Colony Optimization, Cross Layer, Energy, Multihop, Packet Reception Rate, Routing, Velocity, Wireless sensor Network

Title of the Paper: Advanced Implementation of IP Telephony at Czech Universities


Authors: Miroslav Voznak

Abstract: IP telephony is convenient way of communication and brings number of benefits. One of them is the fact that many services can be implemented in a original way and it opens new field of research and is a challenge for designers of communication solutions especially based on open-source platform. This article describes proposal and advanced implementation of IP telephony which have been arisen in Czech academical environment, concretely in a group of IP telephony acting under Czech Education and Scientific Network association. Author is a senior researcher in this group and he decided to describe the most considerable voice over IP implementations at Czech universities and share knowledge with other experts interesting in IP telephony.

Keywords: IP telephony, ENUM, SIP, H.323, Asterisk, OpenSER

Issue 11, Volume 9, November 2010

Title of the Paper: Decoding Shortened Reed Solomon Codes at Bit Level


Authors: Ta-Hsiang Hu, Ming-Hua Chang

Abstract: This study presents a novel means of shortening a Reed Solomon (RS) code at the bit level, yielding only shortened BCH subcodes. With the use of a certain basis, an RS codes over is mapped onto a binary image[4], which contains m concatenated BCH sub-codewords and some glue-vector codewords. With the proposed approach, there only exist some shortened BCH subcode generators in the diagonal entries of the corresponding binary image generator matrix of an RS code. Hence, only binary codewords of shortened BCH subcodes exist in concatenation. When such a codeword is transmitted, BCH decoders or an RS decoder can be adopted at the receiver. In simulations of a BPSK coherent system over AWGN channels, the error performance of BCH algebraic decoding is better than that of RS algebraic decoding. The coding gain between both decoding algorithms becomes obvious as the code rate reduces or the error correcting capability of an RS code increases. At the word error rate 10-5, the code gain can reach as much as 1.5 dB at the code date 0.747. Additionally, with the proposed method for shortening RS codes over GF(28), such a shortened RS code can be decoded by two or three BCH decoders in parallel, which greatly reducing the decoding times and computational complexity.

Keywords: RS decoding, shorten RS codes, shorten BCH codes, binary images

Title of the Paper: Distributed Position Localization and Tracking (DPLT) of Malicious Nodes in Cluster Based Mobile Ad Hoc Networks (MANET)


Authors: Shakhakarmi Niraj, Dhadesugoor R. Vaman

Abstract: In this paper, a robust distributed malicious node detection and precise localization and tracking method is proposed for Cluster based Mobile Ad hoc Network (MANET). Certificate Authority (CA) node is selected as the most stable node among trusted nodes, surrounded by Registration Authority nodes (RAs) in each cluster to generate the Dynamic Demilitarized Zone (DDMZ) to defend CA from probable attackers and mitigate the authentication overhead. The RAs also co-operate with member nodes to detect a target node and determine whether it is malicious or not, by providing the public key certificate and trust value. In addition, Internet Protocol (IP) based Triangulation and multi-lateration method are deployed based on using the average time difference of Time of Arrival (ToA) and Time of Departure (ToD) of the management packets. Triangulation uses three reference nodes which are elected within each cluster based on Best Criterion Function (BCF) to localize each member node inside the cluster in 2D. Multi-lateration is employed to localize the malicious target node in 2D using four neighbor nodes. After localization of two consecutive positions, the target node is continuously localized and tracked by a particular node using the modified real time Position Localization and Tracking (PL&T) algorithm by adaptive beam forming and mapping the energy contours of tracking zone into coverage radii distance. The performance of the proposed scheme demonstrates the significant accuracy in the detection of malicious nodes within each cluster.

Keywords: Koay - Distributed Position, Localization, Tracking (PL&T), Malicious node, Mobile Ad hoc Networks

Title of the Paper: Null Steering of Dolph-Chebychev Arrays using Taguchi Method


Authors: Abelmadjid Recioui, Hamid Bentarzi

Abstract: Dolph-Chebychev arrays are known to exhibit the best compromise between sidelobe level and directivity. However, they place a constraint on the null locations. Any attempt to impose nulls or get them deeper will impact the directivity/sidelobe level trade-off. In this work, null placement in Dolph-Chebychev arrays through element position perturbation is carried out based on Taguchi method all while preserving the array aperture. Several examples are considered for single, double, multiple and broad null placement to demonstrate the ability of the Taguchi method to explore the search space and reach the global optimum.

Keywords: Pattern Nulling, Dolph-Chebychev arrays, Taguchi method, Element position perturbation

Title of the Paper: Capacity of MIMO System in the Presence of Directional Interferences


Authors: Jie Wang, Zhonghao Zhang, Yuehuan Gong

Abstract: Capacity of Multiple Input Multiple Output (MIMO) system degrades significantly in the presence of interferences, especially in the presence of strong directional interferences in military communication scenario. In this paper, the capacity of a MIMO system with directional interferences is investigated. The focus is on the case where the channel state information (CSI) is known to the receiver but unknown to the transmitter. Further, attention is restricted to narrowband MIMO system. The capacity of a MIMO system with directional interferences is derived respectively for deterministic and random fading MIMO channels. And the asymptotic lower limit in high interference-to-noise ratio (INR) is also analyzed. It is indicated that the relationship between the numbers of receive antennas and interferences is critical to the capacity in high INR. The number of receive antennas should be greater than that of interferences in order to ensure the system work normally in high INR, and the corresponding capacity limit approaches the capacity of another MIMO system using same number of transmit antennas and fewer receive antennas without interference. Moreover, the impacts of the correlation and directions of the interferences on capacity are discussed respectively. It is indicated that higher correlation and closer directions of the interferences both yields higher capacity. Monte Carlo simulation results are given and well coincide with our theoretical analysis results.

Keywords: MIMO, capacity, directional interference

Title of the Paper: An Uncapacitated Facility Location Based Cluster Hierarchy Scheme on Wireless Sensor Networks


Authors: I-Hui Li, I-En Liao, Feng-Nien Wu

Abstract: Cluster-Head (CH) nodes function as gateways between the sensors and the Base Station, in Wireless Sensor Networks with a cluster hierarchy. The total energy dissipation of the sensors can be reduced by optimizing the load balance within the cluster hierarchy. This paper proposes an uncapacitated facility location based cluster scheme in which the system lifetime is extended by adding an additional layer of Super- Cluster-Head (SCH) nodes, in order to ease the transmission load of the CHs and to balance the load distribution within the network. The SCH layer is configured using an uncapacitated facility location algorithm in which the facility and service costs are defined in terms of both the energy and the transmission distance. The simulation results confirm that the proposed method yields a better load balance in the SCH layer than that obtained using either a random configuration or a round-robin scheme. Finally, it is shown that irrespective of the size of the sensor field, the proposed scheme outperforms the conventional LEACH-C two-layer scheme in terms of the average energy dissipation of the nodes, the average survival times of the nodes, and the overall system lifetime.

Keywords: Wireless Sensor Network, Gateway Node, Cluster hierarchy, Uncapacitated Facility Location Problem

Issue 12, Volume 9, December 2010

Title of the Paper: Transmission through Single and Multiple Layers in the 3-10 GHz Band and the Implications for Communications of Frequency Varying Material Dielectric Constants


Authors: A. Yahalom, Y. Pinhasi, E. Shifman, S. Petnev

Abstract: In this work we describe a model taking into account transmission through single and multiple layers which are a consequence of the inhomogeneity of the building materials our indoor environment is made of. Our model enables the analysis of a communication channel for both the narrow and wide band cases between adjacent rooms. We compare our analysis with real world measurements performed in our laboratory and obtain an adequate correspondence between our model results and the measurement. Our results indicate that the dielectric constant of the materials is frequency dependent.

Keywords: Communications, RF, Propagation Models

Title of the Paper: Ultra Wideband Wireless Comunications in the 60 GHz Band


Authors: Y. Pinhasi, A. Yahalom, G. A. Pinhasi, M. Lutvak

Abstract: The growing demand for broadband wireless communication links and the lack of wide frequency bands within the conventional spectrum causes us to seek bandwidth in the higher microwave and millimeter-wave spectrum at Extremely High Frequencies (EHF) above 30GHz. One of the principal challenges in realizing modern wireless communication links in the EHF band is phenomenon occurring during electromagnetic wave propagation through the atmosphere. Space-frequency theory of the propagation of an ultra-wide band radiation in dielectric media is presented. Characterization of the atmospheric medium is via its refractivity leading to a transfer function, which describes the response of the medium in the frequency domain. This description enables the consideration of broadband signals taking into account inhomogeneous absorptive and dispersive effects of the medium. Analytical expressions are derived when a pulse-modulated signal is propagating in a general dielectric material. We demonstrate the approach by studying propagation of ultra-wide band signals, while transmitted in the vicinity of the 60GHz absorption peak of the atmospheric medium at millimeter wavelengths.

Keywords: Ultra-wide Band, Extremely high frequencies, Broadband wireless communications, Atmosphere

Title of the Paper: Performance Evaluation of Automatic Switched-Beam Antennas for Indoor WLAN Systems


Authors: Monthippa Uthansakul, Peerapong Uthansakul, Paleerat Wongchompa

Abstract: In this paper, the design of a compact low cost switched-beam antenna for users in Wireless Local Area Networks (WLAN) is introduced. Four antenna elements are arranged in 2?2 lattice. The modification of beamforming network based on Butler matrix is originally proposed for 2?2 planar array. The design is verified through computer simulations and also the prototype of automatic switched-beam antenna is constructed to confirm its performance. Moreover, the validation of performance enhancement is investigated through the signal strength measurements at the users operating in existing WLAN infrastructure. The results confirm the advantage of switched-beam antenna employing modified Butler matrix by improving signal strength with average power of 4.37 dB over the use of omni-directional antenna.

Keywords: Antenna arrays, Beamforming, Butler matrix, Measurement, Signal strength, WLAN

Title of the Paper: Implementation of Beam Formation for WMNs


Authors: M. Uthansakul, S. Pradittara, P. Uthansakul

Abstract: A low-cost beamformer capable of main beam and null locating is proposed in this paper. This beamformer is suitable for WMNs as the positions of mesh router are fixed. The beamformer consists of 2?2 rectangular array spaced by λ/4 accompanied with a simple beamforming network. With multiplying constant values to output signals from beamforming network, null locating can be accomplished. Firstly, its beamforming capability is tested through computer simulation. Then, a prototype of the beamformer is constructed and tested to confirm its performance in term of signal strength, throughput and delay. Also, the impact of position shift which mesh router is not located on the expected beam direction has also been investigated.

Keywords: Antenna array, Beamforming, Null steering, WMNs

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