Volume 4, Issue 1, August 2010


On Selfish Behavior in TDMA-based Bandwidth Sharing Protocols in Wireless Networks  [Full Text]

Dung T. Tran, Department of Computer Science, University of Texas at Dallas, Richardson, TX 75080
Zhiming Chen, Department of Computer Science, University of Texas at Dallas, Richardson, TX 75080
Andras Farago, Department of Computer Science, University of Texas at Dallas, Richardson, TX 75080


Abstract—In TDMA-based protocols, if bandwidth is allocated on the basis of reservations, the base station relies on the stations' requests to allocate time slots to them. Like most other protocols, TDMA-based protocols were designed with the assumption that the stations would follow the rules. However, as mobile devices are becoming more intelligent and programmable, they can selfishly optimize their operations to obtain a larger part of the shared bandwidth. By selfish we designate the users who are ready to tamper with their wireless interface in order to increase their own share of the common
transmission resource. In this paper we study TDMA-based bandwidth allocation protocols in the presence of selfish stations, through game-theoretic perspectives. We show that this game admits Nash equilibria and we provide a bound on the price of anarchy. Since analysis shows that the system throughput at a Nash equilibrium may be neither optimal nor fair among the stations, we designed a new mechanism for use by the base station in practical networks. By our mechanism, the stations cannot increase their benefit by cheating, thus they are motivated to follow the rules. In this work, we demonstrate the robustness of our mechanism by analysis and simulation.


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The Information Economy and Information and Communication Technology
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Mohsen Gerami, Faculty of Applied Science of Post and Communications, Tehran, Iran

Abstract
—Information is a key strategic asset and Information assets are perhaps the most important type of asset in the knowledge-based economy. The Information economy mainly defined by the extension of information and communication technologies.The rapid growth of telecommunications and information technologies in the past decade is shifting the global market from a technology-based economy to an information-based economy. Countries with highly developed telecommunications infrastructure can adjust to this rapid change and take advantage of the enormous new opportunities. This paper describes some of the impacts of the information and communication technologies on the information economy.

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Some Basic Concepts of Grid Computing
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Mohsen Gerami, Faculty of Applied Science of Post and Communications, Tehran, Iran

Abstract—Grid technologies are the convergence of distributed and parallel computing and offer high levels of computational, storage and network capacity. Grid computing named after the similarity with electricity grid. It consist of a number of resources interrelated during a network. Grid computing supports the sharing of distributed resources, and it enables scientists and engineering professionals to solve large scale computing problems. This paper surveys the architecture, types, characteristics and security of grid computing.

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Design of Radio Network for Public Safety Communication in 700 MHz in Greater Jakarta Area
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Djamhari Sirat, Department of Electrical Engineering, Universitas Indonesia, Depok, 16424, Indonesia
Gerson Damanik, Department of Electrical Engineering, Universitas, Indonesia, Depok, 16424,
Indonesia
Filbert H. Juwono, Department of Electrical Engineering, Universitas Indonesia, Depok, 16424, Indonesia
Ardyan I. P. Putra, Department of Electrical Engineering, Universitas, Indonesia, Depok, 16424, Indonesia

Abstrac
t—Public safety is very important to make safe and comfortable condition in the societies to create national stability. Greater Jakarta, as the capital city of Indonesia, needs a reliable communication system to support coordination among public agencies. This paper discusses about designing of radio communication network in 700 MHz in Greater Jakarta with demand prediction until year 2020. Supporting technologies used are LTE and mobile WiMAX. The Base Station (BS) capacity, spectrum demand, advantages, and drawbacks will be analysed. In addition, it discusses about the handling and coordination
scenarios of the system. It needs 19 BSs for LTE and 16 BSs for WiMAX to cover Greater Jakarta area and Seribu islands. The capacities for each sector needed are 9 Mbps and 10 for LTE and mobile WiMAX respectively in 2010, 12 Mbps and 19 Mbps for LTE and mobile WiMAX respectively in 2015, and in 2020 it needs 19 Mbps and 24 Mbps for LTE and mobile WiMAX respectively.

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Implementation of DSSS Technology in Multipath Environment Using SDR
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Nirmalendu Bikas Sinha, Department of ECE and EIE , College of Engineering & Management, Kolaghat, K.T.P.P Township, Purba- Medinipur, 721171, W.B., India
Kaustav Chowdhury, Department of ECE, College of Engineering & Management, Kolaghat, K.T.P.P Township, Purba-Medinipur, 721171, W.B., India
M.Mitra is with the Bengal Engineering and Science University, Shibpur,W.B,India

Abstrac
t— In an effort to develop a complete DSSS system for ITS application in our day-to-day life, the authors have experienced a lot of experimentation and modelling which has been put to use for exploting the best possible design. Nowadays, one of the major threats in the field of wireless communication is jamming. Many anti-jamming techniques have been developed in the recent past. Presently known anti-jamming techniques require the communicating devices to have a pre-shared secret that can be used as a secret spreading key between two communicating devices. For DSSS based anti-jamming scheme, the secret key is used to derive the code sequences. The transmitted signal, in this case propagates though the channel undetected by anyone who may be listening. Traditionally, wireless security is considered in link layer design and media access control (MAC) management, including data encryption algorithms and key management in cooperative communication systems. DSSS systems is found to deal with wireless security issues very efficiently at the MAC layer.The performance of the system is critically analysed in presence of narrowband and wideband interference signals in this paper and a highly efficint interference rejection technique is developed for multipath environment using RAKE receiver. It has finally been implemented using SDR in the newly developed DSSS based communication system .

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A Simple and Efficient Microstrip Diplexer with Stubs
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M. Khalaj-Amirhosseini, Iran University of Science and Technology, Tehran, Iran
S. A. Akbarzadeh-Jahromi, Iran University of Science and Technology,
Tehran, Iran

Abstract
— In this paper, a new microstrip structure for diplexers is proposed. The proposed diplexer has only four stubs and two transmission lines with the same characteristic impedances while it has a good transmission performances and high isolation between the output ports. A microstrip diplexer is designed and fabricated with 1.0/2.0 GHz response. Measured results of the fabricated diplexer have a good agreement with the calculated results.

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CDBA-Based Electronically Tunable Filters and Sinusoid Quadrature Oscillator  [Full Text]

R. Nandi , Department of ETCE, Jadavpur University, Kolkata, 700032, W.B., India
P.Venkateswaran, Department of ETCE, Jadavpur University, Kolkata, 700032, W.B., India
Soumik Das, Department of AEIE, Heritage Institute of Technology, Kolkata, 700107, W.B., India
M. Kar, Department of ECE, Heritage Institute of Technology, Kolkata, 700107, W.B., India

Abstract
—— New Current Differencing Buffered Amplifier (CDBA) - based multifilter function topologies are presented. Electronic tuning is derived by appropriate insertion of a multiplier element whose control voltage (Vc) tunes the select frequency in a range of 200KHz ≤ fo ≤ 1MHz. The circuits also realize a voltage controlled quadrature oscillator (VCQO) with suitable design. Analysis on the effects of the CDBA-parasitic components indicates low active-sensitivity and good frequency-stability of the oscillator. The multifunction performance has been verified both with PSPICE macromodel simulation and by hardware circuit tests. A novel method of measuring the oscillator frequency-tuning error (ıf) based on the Nyquist plot is presented that shows ı f ≈ 2%.