WSEAS Transactions on Communications

Print ISSN: 1109-2742
E-ISSN: 2224-2864

Volume 12, 2013

Issue 1, Volume 12, January 2013

Title of the Paper: Algorithmic Vertical Handoff Decision and Merit Network Selection Across Heterogeneous Wireless Networks

Authors: Sunisa Kunarak, Raungrong Suleesathira

Abstract: Next generation wireless networks must be able to coordinate services between heterogeneous networks through multi-mode mobile terminals. Such heterogeneity poses a challenge to seamless handover since each access network has different operations. In this paper, the policies of multiple metrics for handoff to permit connectivity across UMTS and WLAN/WiMAX are designed. Moreover, how to select an optimal target network is an important issue to balance against the network condition and user preference. The considered metrics for handoff initiation include the predicted received signal strength (RSS) of neighbor networks and dwell time. The RSS is predicted by back propagation neural network which is beneficial to perform handoff early. Dwell time value depends on the user speed and moving pattern. The policy for triggering a handoff is that the RSS conditions are consistently true during dwell time, so that unnecessary handoffs are avoidable. The predictive RSS and current RSS conditions have different policies for real time and non-real time services in different networks. Policies in the merit function are presented to select an optimal network. The weighting factors in the merit function are dynamic to neighbor networks. To evaluate the algorithm, RSS prediction, network selection performance and handoff decision performance are considered. The results indicate that the proposed vertical handoff decision algorithm and network selection outperforms the other two approaches in performing handoff earlier and reducing the number of vertical handoffs, connection dropping, Grade of Service (GoS) while increasing the average utilization per call of WLAN/WiMAX networks.

Keywords: Dwell time, Handoff decision policy, Heterogeneous wireless network, Network selection, Vertical handoff

Title of the Paper: Performance Analysis and PAPR Reduction of Coded OFDM (with RS-CC and Turbo coding) System using Modified SLM, PTS and DHT Pre-coding in Fading Environments

Authors: Alok Joshi, Davinder S. Saini

Abstract: In wireless communication, parallel transmission of symbols using multi carriers is used to achieve high efficiency in terms of throughput and better transmission quality. Orthogonal Frequency Division Multiplexing (OFDM) is one of the techniques for parallel transmission of information. In multipath environment the performance of orthogonal frequency division multiplexing degrades which can be improved by introducing some kind of channel coding. Coded OFDM (COFDM) is the new candidate for application such as Digital audio Broadcast (DAB) and Digital Video Broadcast (DVB-T) due to its better performance in fading environments. However high peak to average power ratio (PAPR) is a major demerit of OFDM system, it leads to increased complexity and reduced efficiency of RF amplifier circuit. In this paper Modified Selective mapping (SLM), Partial Transmit sequence (PTS) and Discrete Hartley Transform (DHT) precoding schemes are proposed for PAPR reduction, where SLM, PTS and DHT precoding schemes are used in conjunction with post clipping and filtering processes. However clipping can degrade the BER performance but the degradation in performance can be compensated by using OFDM with channel coding; here we have used Reed Solomon (RS) codes along with convolution codes (CC) used as serial concatenation and TURBO codes as parallel concatenation code for channel coding purpose. The BER performances are simulated for Additive white Gaussian (AWGN), Rayleigh, Rician and Nakagami (m=3) channels and Complementary cumulative distribution functions (CCDF) curves are simulated for modified as well as ordinary SLM, PTS and DHT precoding techniques. The COFDM system implemented here is as per IEEE 802.11a.

Keywords: RS-CC codes, Turbo codes, Rayleigh, Rician, Nakagami-m, DHT pre-coding, PAPR, PTS, SLM, Clipping- filtering

Title of the Paper: OVSF based Fair and Multiplexed Priority Calls Assignment CDMA Networks

Authors: Vipin Balyan, Davinder S. Saini, Gunjan Gupta

Abstract: Code division multiple access (CDMA) networks uses orthogonal variable spreading factor (OVSF) codes to support different transmission rates for different users which suffers from code blocking limitation. Multiplexing in digitized world is used for data selection. In this paper, calls are multiplexed to share the capacity of the network fairly and with priority using OVSF codes for assignment. A multiplexer is used to provide each call their share of capacity. The different layers shares their capacity with other layer in order to minimize code blocking. Simulation results prove dominance and fairness of our design over other novel schemes.

Keywords: OVSF codes, code blocking, code searches, single code assignment, single code assignment, wastage capacity

Issue 2, Volume 12, February 2013

Title of the Paper: Performance of Selected Diversity Techniques over the α-μ Fading Channels

Authors: Taimour Aldalgamouni, Amer M. Magableh, Ahmad Al-Hubaishi

Abstract: In this paper, approximate closed-form expressions for the bit error rate (BER) of M-ary quadrature amplitude modulation (MQAM) and M-ary phase shift keying (MPSK) are derived considering independent and identically distributed (i.i.d) α-μ fading channels with a maximal ratio combining (MRC) receiver. Moreover, other closed-form expressions are obtained for the symbol error rate (SER) of both MQAM and MPSK under the same channel conditions considering dual branch selection combining (SC) receiver. The derivations for MRC are based on the exponential approximation of the coherent BER formula for both MQAM and MPSK. For dual branch SC, the derivations are based on very accurate SER approximation for both MQAM and MPSK. The derived expressions can reduce to study the BER performance over other fading channels such as; Rayleigh, Weibull, and Nakagami-m, as special cases. Numerical results are also provided for the derived expressions and they show close match with Monte-Carlo simulations, especially for the case of dual branch SC.

Keywords: Maximum Ratio Combining (MRC), Selection Combining (SC), the -μ fading channel, generalized fading model, M-ary Quadrature Amplitude Modulation (MQAM), M-ary Phase Shift Keying (MPSK), Bit Error Rate (BER), and Symbol Error Rate (SER).

Title of the Paper: Performance Comparison of Spreading Codes in Linear Multi-User Detectors for DS-CDMA System

Authors: J. Ravindrababu, E. V. Krishna Rao

Abstract: Direct Sequence Code Division Multiple Access (DS-CDMA) system is well known wireless technology. This system suffers from MAI (Multiple Access Interference) caused by Direct Sequence users. Multi-User Detection schemes were introduced to detect the users’ data in presence of MAI. Linear Multi-user Detectors and conventional Matched Filter (MF) are simulated using gold, PN and even kasami sequences as spreading codes in DS-CDMA system. In this paper odd kasami sequence is proposed. For this, odd kasami sequence of length L=2m which inclusive of initial bit, The Bit Error Rate (BER) performance of MMSE Detector provides better than Decorrelating detector and conventional Matched filter. Comparative Study shows that the proposed odd kasami sequence is better performed than gold, PN and even kasami sequences in linear Multi-user Detectors and conventional Matched Filter (MF).

Keywords: Multi-user detection, Matched filter, Decorrelating detector, MMSE, DS-CDMA, PN sequence, gold sequence, even kasami sequence and odd kasami sequence

Title of the Paper: Three-Dimensional Model of Cylindrical Monopole Plasma Antenna Driven by Surface Wave

Authors: Zili Chen, Anshi Zhu, Junwei Lv

Abstract: In the recent research on cylindrical monopole plasma antenna excited by surface wave, several basal theoretical problems for the radiation of plasma antenna are investigated. Many meaningful results about plasmas antenna, e.g. the analysis of physical characteristics, numerical calculation methods, software simulation, diagnosis of parameters, etc. have already been obtained. As known that the plasma antennas have reconfigurable properties and many physical parameters of plasma antenna are governed by the applied electromagnetic field and actual coupling method, so model research of plasma antenna is very necessarily in its further investigations and applications. But the precise model of monopole plasma antenna according to its three-dimensional structure has not been proposed yet, the three-dimensional model is proposed in the paper, three-dimensional distributions of electric and magnetic fields around monopole plasma antenna are analyzed. The related formulas and equations of the model are derived by applying molecular dynamic theories and Maxwell-Boltzmann equations; in addition, numerical simulation methods are adopted to verify validity of the proposed model.

Keywords: Cylindrical Monopole Plasma Antenna; Surface wave; Three-Dimensional Model; Calculation

Issue 3, Volume 12, March 2013

Title of the Paper: Mobile Communication Safety on Road Transport

Authors: H. Abdul Shabeer, R. S. D.Wahida Banu

Abstract: Telecommunication industry is the world's fastest growing industry with 5.3 billion mobile subscribers (that's 77 percent of the world population) around the globe. This significant rise in cellular phone use has served as the catalyst for major road accidents. They can be extremely distracting and cause careless and unavoidable accidents. Many people have been injured and even killed because of wireless customers and their over-bearing cell phones. With the aim of preventing such types of accidents, we propose a highly efficient automatic electronic system for early detection of incoming or outgoing call, an antenna located on the top of driver seat used for detecting when the driver uses mobile phone and an safety application named (Profile Changer) has developed using J2ME that will automatically loaded on the drivers cell phone which helps in reducing the risk of accidents from occurring, while also ensuring the user need not worry about missing urgent calls. We have extended our research by evaluating the outcome obtained with 2010 study from the US National Safety Council and we have also shown the extent to which this application helps to reduce economic losses in India.

Keywords: Mobile application to prevent accidents; cell phone while driving; Indian Economic loss due to cell phone accidents, Driver detection, Distraction

Title of the Paper: Multi-Objective Cross-Layer Optimization with Pareto Method for Relay Selection in Multihop Wireless Ad hoc Networks

Authors: Nyoman Gunantara, Gamantyo Hendrantoro

Abstract: The focus of this paper is cross layer optimization of relay selection on multihop wireless ad hoc networks. Cross-layer metrics that will be optimized are power consumption, throughput, and load balancing in wireless ad hoc networks for the outdoor and indoor configurations. Those three resources (performance indicators) are optimized using the multi objective optimization with Pareto method. The results obtained apply a dynamic ad hoc network model and optimization can be done simultaneously to all three resources which are optimized based on the route or path. Several alternatives in the relay selection are shown in the following simulation. The selection of the optimal relay can be based on one or a combination of the three performance indicators. The performance of the optimal relay selection in the field of POF (Pareto Optimal Front) is shown by the shortest Euclidean distance. The result of optimization for indoor and outdoor multihop ad hoc networks with three performance indicators is shown.

Keywords: Multi Objective Optimization, Cross Layer, Pareto Method, Relay Selection, Euclidean Distance, Multihop Wireless Ad hoc Networks, Performance Indicator, Outdoor and Indoor Configuration

Title of the Paper: An Agent-Assisted Fuzzy Cost Based Multicast QoS Routing in MANETs

Authors: G. Santhi, Alamelu Nachiappan

Abstract: Multicast routing and provision of QoS (Quality of Service) are challenging problems due to the dynamic topology and limited resources in Mobile Ad hoc Networks (MANETs). This paper proposes an agent based QoS routing algorithm that employs fuzzy logic to select an optimal path by considering multiple independent QoS metrics such as buffer occupancy rate, remaining battery capacity of a mobile node number of hops. In this method all the available resources of the path is converted into a single metric fuzzy cost. This is based on multi-criterion objective fuzzy measure. The path with the minimum fuzzy cost is used for the transmission. Here, the intelligent software agents move around the network and collect information of all mobile nodes. These agents can reduce the network delay and participate in network routing and route maintenance. The performance of the proposed Agent assisted Fuzzy cost based Multiobjective QoS Routing protocol (Agent_FCMQR) is compared with E-AOFR (Evolutionary Ad hoc On demand Fuzzy Routing) and MQRFT (Multi metric QoS routing based on Fuzzy Theory) and the simulation results show that the proposed protocol is superior over existing intelligence based routing protocols.

Keywords: MANETs, multicast routing, Quality of Service, mobile agents, multi-objective, fuzzy cost

Title of the Paper: Implementation of Generalized Detector in MIMO Radar Systems

Authors: Vyacheslav Tuzlukov

Abstract: In this paper, we consider the problem of multiple-input multiple-output (MIMO) radars employing the generalized detector (GD) based on the generalized approach to signal processing in noise (GASP) and using the space-time coding to achieve a desired diversity. To that end, we derive a suitable GD structure after briefly outlining the model of the received target return signal. GD performance is expressed in closed form as a function of the clutter statistical properties and of the space-time code matrix. We investigate a particular case when GD requires a priori knowledge of the clutter covariance, i.e., the decision statistics under the null hypothesis of “a no” target is an ancillary statistic in the sense that it depends on the actual clutter covariance matrix but its probability density function (pdf) is functionally independent of such a matrix. Therefore, threshold setting is feasible with no a priori knowledge as to the clutter power spectrum. As to the detection performance, a general integral form of the probability of detection is provided, holding independent of the searched object fluctuation model. The formula is not analytically manageable, nor does it appear to admit general approximate expressions, which allow giving an insightful look in the MIMO radar system behaviour. We thus restrict our attention to the case of Rayleigh-distributed target attenuation (Swerling-1 model). To code construction we use an information-theoretic approach and compare conditions for code optimality with ones for classical Chernoff bound. This approach offers a methodological framework for space-time coding in MIMO radar systems constructed based on GASP, as well as simple and intuitive bounds for performance prediction.

Keywords: Generalized detector, multiple-input multiple-output (MIMO), Rayleigh fading, Chernoff bound, generalized approach to signal processing, Swerling-1 model

Title of the Paper: A Modified PTS Combined with Interleaving and Pulse Shaping Method Based on PAPR Reduction for STBC MIMO-OFDM System

Authors: P. Mukunthan, P. Dananjayan

Abstract: Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) system have been proposed in the recent past for providing high data-rate services over wireless channels. When combined with space time coding it provides the advantages of space-time coding and OFDM, resulting in a spectrally efficient wideband communication system. However, MIMO-OFDM system suffer with the problem of inherent high peak-to-average power ratio (PAPR) due to the intersymbol interference between the subcarriers. To overcome this problem, the partial transmit sequence (PTS) based on PAPR reduction by optimally combining signal subblocks and the phase rotation factors is considered. As the number of subblocks and rotation factors increases, PAPR reduction improves. The number of calculation increases as the number of subblocks increases, such that complexity increases exponentially and the process delay occur simultaneously. In this paper, PAPR reduction schemes based on a modified PTS combined with interleaving and pulse shaping method for STBC MIMO-OFDM system has been presented. The paper analyses the influence of the number of the detected peaks on PAPR reduction performance and on complexity, and then obtain the optimal parameter to achieve better PAPR reduction performance and lower complexity. Simulation results show that the proposed modified PTS with interleaving and the pulse shaping method can obviously improve PAPR performance in the MIMO-OFDM system.

Keywords: MIMO-OFDM, PAPR, STBC, Partial Transmit Sequences, Interleaved Subblock Partition Scheme, Raised-Cosine pulse shape

Issue 4, Volume 12, April 2013

Title of the Paper: Performance Analysis, Improvement and Complexity Reduction in Multi Stage Multi-User Detector with Parallel Interference Cancellation for DS-CDMA System Using Odd Kasami Sequence

Authors: J. Ravindrababu, E. V. Krishna Rao

Abstract: Direct Sequence Code Division Multiple Access (DS-CDMA) system is well known wireless technology. This system suffers from MAI (Multiple Access Interference) caused by Direct Sequence users. Multi-User Detection schemes were introduced to detect the users’ data in presence of MAI. In Multi stage Partial parallel interference cancellation (MP-PIC) method complexity is more than multi stage conventional PIC (MC-PIC), but performance is better than MC- PIC. In This paper we proposed multi stage subtractive PIC (MS-PIC). In this method the complexity is less than MP-PIC and performance is slightly less than MP-PIC. Now we proposed one more method that is the combination of partial and subtracting parallel interference cancellation (PS-PIC) in multi stage. This method gives to achieve performance improvement and complexity reduction compared to conventional multistage PIC detector.

Keywords: Multi-user detection, MAI, Matched filter, , DS-CDMA, PIC.odd kasami sequence

Title of the Paper: Reconfigurable Characteristics of the Monopole Plasma Antenna and Its Array Driven by Surface Wave

Authors: Anshi Zhu, Zili Chen, Junwei Lv

Abstract: Reconfigurable characteristics of monopole plasma antenna are investigated in the paper, related analysis and experiments on the reconfigurable characteristics of the plasma antenna e.g., working frequency, radiation pattern are completed and many experimental results are obtained. The research results show that the reconfigurable characteristics of monopole plasma antenna can be realized and optimized under certain external excited conditions. The radiation parameters the plasma antenna array also can be reconfigured through changing variable parameters of the plasma elements, the related analysis and simulations are presented.

Keywords: Monopole Plasma Antenna, Plasma Antenna Array; Reconfigurable Characteristics, Surface Wave, Research

Title of the Paper: A Systematic Design of High-Rate Full-Diversity Space-Frequency Codes for Multiuser MIMO-OFDM System

Authors: R. Shelim, M. A. Matin, A. U. Alam

Abstract: The authors have proposed a new space-frequency (SF) code for MIMO-OFDM system in their paper. The data streams of all the users are sent simultaneously through all the OFDM sub-channels. The proposed SF code can achieve high symbol rate ( rate ) with full diversity ( ) where denotes the number of transmit antenna for each user, denotes number of receive antenna at the receiver and denotes the number of independent channel taps. The threaded algebraic layering concept is used to construct this SF code which combines the space-frequency layering theory with algebraic component codes. The component code is considered to be an algebraic number theoretic constellation. Each component code is assigned to a “thread” and interleaved over space and frequency. Diophantine approximation theory is then used to make the threads transparent to each other. In addition, another approximation is used so that the users become transparent to each other. Our SF code does not require zero-padding, which always ensures high symbol rate. It is proved through simulation that the proposed coding scheme achieves higher coding and diversity gain over recently proposed space-frequency code.

Keywords: MIMO-OFDM systems, wideband multipath fading channels, multiple access channel (MAC), multiuser space-frequency (SF) coding, and threaded algebraic layering concept

Title of the Paper: The Equivalent Queuing Model by a Partition Algorithm for Tree Connected Servers

Authors: Chung-Ping Chen, Ying-Wen Bai, Hsiang-Hsiu Peng, Ying-Yu Chen

Abstract: This paper aims at analysis efficiency in estimating the performance of tree connected servers. We use a queuing model to represent their equivalent performance and service quality. The queue types of the connection servers can be classified as serial, parallel and tree connections. We design an algorithm to simplify the equivalent serial-parallel queues. According to the equivalent queues we compute the system response time of tree connected servers. We use a network simulation and an analytical software tool to represent the equivalent performance of the queue. Our simulation uses various different service rates and arrival rates of the queue models and finds the system response time. We also measure the average system response time in comparison with the simulation result to find out the service rates of the actual servers and evaluate the accuracy of the algorithm. We will find that the error margin of measurement, simulation and computing ranges from 1.37%-19.27%.

Keywords: Serial-parallel Network, Web Servers, Service Rate, Tree Connected Servers, System Response Time, Equivalent Queuing Network

Title of the Paper: A New Finite Word-length Optimization Method Design for LDPC Decoder

Authors: Jinlei Chen, Yan Zhang, Xu Wang

Abstract: A new word-length optimization method based on Monte Carlo simulation is proposed. The word-length of the check node extrinsic message is also further optimized in this paper. In the proposed optimization method, and in the process of optimizing the word-length of the channel data, the statistical distribution results of variable node’s posterior probability data and check node’s extrinsic message are also obtained. The optimized word-length of variable node’s posterior probability data and check node’s extrinsic message is concluded by the statistical distribution result and the BER (Bit Error Rate) curves. Compared to the pure Monte Carlo simulation, the proposed method could reduce the amount of simulation work by more than 50%, and have the same word-length optimization results.

Keywords: LDPC decoder, word-length optimization, Monte Carlo simulation, min-sum

Issue 5, Volume 12, May 2013

Title of the Paper: Error Correction and Equilibrium investigation in Random Access MAC Protocols for Wireless Networks

Authors: Mohamed Lamine Boucenna, Hadj Batatia, Malek Benslama

Abstract: This research focuses on network performance, and how to solve the problem of low throughput in the Aloha medium access control (MAC) protocol and its derivatives. For this purpose, we propose two complementary solutions. The first consists of the integration of the erasure coding scheme in this protocol to recover collided packets and to reduce the rate of collision between transmitted packets. Here, since each node sends N coded packets instead of the k original packets, we have (N-k) redundant packets. The introduction of redundancy and subsequently structuring it in an exploitable manner, allows serious errors injected by the channel to be corrected. However, if each node attempts to achieve its best output without regard for the other nodes’ actions, this could affect overall system throughput. To analyze such conflicting situations where the action of one node has an impact on the other nodes’ actions, we add a complementary solution, which is based on the game theory technique of acquiring network equilibrium. This makes the network stronger and able to resist many collisions.

Keywords: Slotted-Aloha, CSMA, Erasure Coding, Game theory

Title of the Paper: Design of Flexible Layer-3 Routing Protocol with Variable-Length Address Information and Its Implementation

Authors: Yasuhiro Sato, Yusuke Toji, Shingo Ata, Ikuo Oka

Abstract: In next-generation network architectures, the number of nodes and equipment connected to information networks increase more than ever. Due to the explosive increase of network equipment, an information retrieval technique to access information surely and efficiently will be strongly required. For this, one of the current approaches is intelligent routing, such as DHT, which is implemented on upper layers than IP layer. However, the inefficiency in processing packets and the mutual interference between layers are caused, because similar functions are implemented on different layers as different routing protocols. In this paper, we propose a new layer-3 routing protocol that can achieve flexible information retrieval implemented on overlay networks. For this purpose, we design a new routing protocol that can use variable-length address information, such as keyword or device name, as its address information. Moreover, we consider the feasibility of our routing protocol by implementing it to GNU Zebra as an extension of BGP.

Keywords: Next-generation network, routing protocol, overlay routing, clean-slate architecture

Title of the Paper: Performance of Concatenated Optimized Irregular LDPC Code with Alamouti Coded MIMO-OFDM Systems

Authors: Bhasker Gupta, Davinder S. Saini

Abstract: Multiple input multiple output (MIMO) communication systems along with orthogonal frequency division multiplexing (OFDM) have a great potential for future 4G broadband wireless communications. Recently, low density parity check codes (LDPC) achieves good error correcting performance and capacity near Shannon’s limit. In this paper, we considered the performance analysis of serially concatenated regular and irregular LDPC codes with Alamouti space time block coded (STBC) and space frequency block coded (SFBC) MIMO-OFDM systems for high data rate wireless transmission. Currently, most of the research related to this area is concentrated on the impact of increase in code rate and diversity of the system but not on increase in coding gain. In this paper, we analyzed the impact of increasing coding gain. Performance analysis and design optimization is carried out using density evolution (DE) tool with mixture of Gaussian approximations over Rayleigh independent and identically distributed (i.i.d) channels

Keywords: MIMO-OFDM, Alamouti codes, Density Evolution (DE), LDPC codes, Maximum a Posteriori (MAP), Maximum Likelihood (ML) detection

Title of the Paper: Performance Analysis of Channel Coding in Satellite Communication Based on VSAT Network and MC-CDMA Scheme

Authors: Mohammed El Jourmi, Hassan El Ghazi, Abdellatif Bennis, Hassan Ouahmane

Abstract: Satellites are an essential part of our daily life, and they have a very large usage ranging from Search and Rescue Operations to Environmental Monitoring. The widest use of satellites is, however, in communication systems. Satellites can cover vast areas on the world; therefore, they are the nodes where all links pass through in a communications network. Many users can access such a network simultaneously while they are widely separated geographically. The purpose of this paper is to model and analyze a geostationary satellite communication system with VSATs networks in the uplink case, using Multicarrier CDMA system (MC-CDMA is a combination of multicarrier modulation scheme and CDMA concepts) and channel coding mechanisms “Turbo code and Convolutional code”. The envisaged system is examined in Ku band and over AWGN channel. The simulation results are obtained for each different case. The performance of the system is given in terms of Bit Error Rate (BER) and Signal to Noise Ratio (SNR). In this study the proposed system coded with Turbo code can achieve better error rate performance compared to coded VSAT MC-CDMA system with convolutional code.

Keywords: VSAT Network, Turbo code, Convolutional code, MC-CDMA, Ku band, Satellite communication, Uplink

Title of the Paper: Mobility Scenario-Based Performance Evaluation of Preemptive DSR Protocol for MANET

Authors: V. Ramesh, P. Subbaiah

Abstract: Ad hoc wireless networks are characterized by multi-hop wireless connectivity, infrastructure less environment and frequently changing topology. To analyze the performance of routing protocols in MANETs in the real world, a scenario based simulation analysis is required since there is a lack of necessary infrastructure for their deployment. Most of the earlier work done in this field have assumed the Random Waypoint model, which fails to capture the realistic movement of the nodes. In this paper, we describe a set of experiments conducted to analyze the performance of the Preemptive DSR routing protocol in a battlefield scenario. BonnMotion Software(Java based) is used to create and analyses mobility scenarios. Initially an explanation of the experimental metrics and the setup is described, followed by the scenarios used for our simulations. The results give an idea of how the Preemptive DSR protocol behaves in the given scenario and helps identify the metrics for optimal performance of the protocol.

Keywords: MANET, PDSR, battlefield scenario, Packet Delivery Ratio, delay

Issue 6, Volume 12, June 2013

Title of the Paper: MC/DS-CDMA versus SC/DS-CDMA in Mobile Radio: Spectral Efficiency Approach

Authors: P. Varzakas

Abstract: The spectral efficiency of a multicarrier direct-sequence code-division multiple-access (MC/DS-CDMA) cellular system operating in a mobile radio environment with Rayleigh fading, is investigated. In this work, spectral efficiency is evaluated in terms of channel capacity (in the Shannon sense) per user, estimated in an average sense. It is analytically shown that, under normalized conditions and assuming a static model of operation, MC/DS-CDMA spectral efficiency, on downlink, is higher than that of single-carrier direct-sequence code-division multiple-access (SC/DS-CDMA). This result is justified by the combination of path-diversity reception, achieved by a conventional coherent maximal-ratio combining (MRC) RAKE receiver, and physical frequency diversity potential provided, in a fading environment, by frequency-division multiplexing on a set of orthogonal carriers. It is shown that the increase of the carrier frequencies, in the MC/DS-CDMA cellular system, leads to a respective improvement of the spectral efficiency achieved.

Keywords: Spectral efficiency, multicarrier modulation, code-division multiple access, cellular systems

Title of the Paper: Adaptive Modulation and Coding for Lifetime Enhancement of WSN using Game Theoretic Approach

Authors: R. Valli, P. Dananjayan

Abstract: The fundamental component of resource management in Wireless Sensor Network (WSN) is transmitter power control since the sensors are miniature battery powered devices. Power control is an important research trend in WSNs for improving the efficiency of network communication and prolonging the life time of the network thereby supporting system quality and efficiency. This paper analyses a game theoretic model with pricing in which the game is formulated as a utility maximizing distributed power control game considering the residual energy of the nodes along with adaptive modulation. The game approach considered adapts to the changes in channel condition and selects the appropriate modulation and transmits using the optimal transmission power thereby enhancing the network lifetime. Simulation results show that the game with pricing provides maximum utility by consuming lesser power. The adaptive modulation strategy also minimizes the energy consumption and maximizes the network lifetime by selecting the optimal constellation size.

Keywords: Game theory; power control; adaptive modulation and coding

Title of the Paper: Comparative Analysis of DDR and DAR IMPATT Diodes for Wide Frequency Band

Authors: Alexander Zemliak, Fernando Reyes, Jaime Cid, Sergio Vergara, Evgeny Machusskiy

Abstract: The analysis of Double Drift Region (DDR) and Double Avalanche Region (DAR) IMPATT diodes has been realized on basis of the precise drift-diffusion nonlinear model and special optimization procedure. DDR IMPATT diode includes one avalanche region and two drift regions and DAR IMPATT diode includes two avalanche regions inside the diode and one drift regions both for electrons and holes. The phase delay which was produced by means of the two avalanche regions and the drift region v is sufficient to obtain the negative resistance for the wide frequency band. The admittance and energy characteristics of the DAR diode were analyzed in very wide frequency band from 30 up to 360 GHz. Output power level was optimized for the second and third frequency bands near the 220 and 330 GHz.

Keywords: Implicit numerical scheme, active layer structure analysis, DDR and DAR IMPATT diodes

Title of the Paper: A Predictive Handover Initiation Mechanism in Next Generation Wireless Networks

Authors: Sudesh Pahal, Brahmjit Singh, Ashok Arora

Abstract: Next generation wireless networks are envisaged to be an integration of different wireless networks and demand the ability of users to move from one network domain to another network domain seamlessly. Also these networks require superior handover techniques to provide ubiquitous access to roaming users with maximum network resource utilization. In order to fulfill these requirements, it is essential to select an appropriate time to initiate handover. The handover procedure can be completed before link down only if we have prior information about necessity of handover as well as availability of target network. The link down event and link up event provide information about handover requirement and resource availability respectively. In this paper, a predictive handover initiation mechanism is proposed to select an appropriate time to start handover procedure. Also the prediction initiation time is made adaptive to avoid link failure in high velocity applications which was fixed in conventional algorithms. MATLAB Simulation results show that the proposed mechanism decreases the probability of false handover initiation by 25% and unnecessary handover probability by 35% when compared with existing handover mechanisms in different network overlapping environments.

Keywords: Handover; Prediction; Next generation wireless networks; GSM; WiMAX; Overlapping

Title of the Paper: A Real-Time PC-Based Software Radio DVB-T Receiver

Authors: Shu-Ming Tseng, Jian-Cheng Yu, Yueh-Teng Hsu

Abstract: We propose a PC-based real-time software Digital Video Broadcasting-Terrestrial (DVB-T) receiver, including hardware, driver, and software parts. The total data rate of DVB-T is much greater than that of Digital Audio Broadcasting (DAB). A more efficient signal processing algorithm than our previous software DAB receiver is necessary to improve the speed of the software part of the DVB-T receiver. Therefore, we propose some modifications in software: Viterbi algorithm optimization, and Digital-Down-Converter (DDC) optimization. Finally, it only takes 1541 ms to decode the 2760ms video data in this system, and the data recoded at 100km/hr vehicle speed is successfully decoded.

Keywords: Software radio, mobility, Digital Video Broadcasting, orthogonal frequency-division multiplexing

Title of the Paper: Reliability Level List Based Direct Target Codeword Identification Algorithm for Binary BCH Codes

Authors: B. Yamuna, T. R. Padmanabhan

Abstract: In BCH coded schemes the reliability information available with the demodulated bits can be effectively used for soft decision decoding (SDD) to improve signal to noise ratio performance. Chase algorithms, their adaptations, and modifications available for SDD trade complexity for performance to different levels. A new iterative algorithm – Reliability Level List based Direct Target Codeword Identification Algorithm (DTCI) - is proposed in the paper; the algorithm yields the best that is possible with SDD. The concept of reliability level list (RLL) introduced in the paper is central to the application of the algorithm. At every stage of the iterative process followed, the algorithm uses the reliability information of the bits and identifies the next most likely candidate word to be examined. This ensures that the correct decoded codeword is identified through the shortest number of steps. Detailed simulation studies with different BCH codes amply bring out the effectiveness and superiority of the algorithm.

Keywords: BCH codes, Reliability based decoding, Soft decision decoding, Probability of error

Issue 7, Volume 12, July 2013

Title of the Paper: Accurate Closed-Form Approximations for the BER of Multi-Branch Amplify-and-Forward Cooperative Systems with MRC in Rayleigh Fading Channels

Authors: Amer M. Magableh, Mustafa M. Matalgah

Abstract: Relay-based cooperative systems have recently attracted significant attention since they enable exploiting the inherent spatial diversity of wireless networks with single antenna terminals. In this paper, the authors address the error performance of a cooperative diversity network consisting of a source, a destination, and multiple dual-hop amplify-and-forward (AF) relays in Rayleigh fading channels, in which the source broadcasts the signal to the relays in the first time slot and the relays simultaneously forward signals to the destination in the second time slot. Analytically studying the error performance of multiple dual-hop AF cooperative networks with maximal ratio combining (MRC) receivers at the destination and deriving closedform expressions has always been a difficult task. Considering an L-Relay nodes AF cooperative network in Rayleigh fading channels employing MRC, closed-form approximate expressions are derived for the bit error rate (BER) of a class of coherent modulation techniques that are easy to calculate, thus circumventing the computational inefficiency of the exact formulation. Exact results obtained using numerical integration are provided to validate the tightness of the proposed expressions. In addition, a slight modification for the amplification gain at the relay-node is proposed, which showed an improvement in the effective signal-to-noise ratio at the destination node.

Keywords: Cooperative communication, amplify-and-forward, Rayleigh fading, bit error rate, maximal ratio combining, and Prony approximation

Title of the Paper: Dynamic Position Location and Tracking (D-PL&T) using Location based Hash Scheme for Malicious Detection under Doppler Spread Rayleigh Channel

Authors: Niraj Shakhakarmi, D. R. Vaman

Abstract: A novel approach of the integrated security and dynamic Position Location and Tracking (PL&T) for malicious node maintaining two friendly nodes is proposed. Location based hash security scheme is deployed for detection of friendly and malicious nodes by encrypting hash functions using private location assets to increase the security level. In addition, PL&T is deployed forming the robust tracking zone and triangulation using two friendly nodes equipped with steered Directional antenna in Mobile Ad hoc Networks. The integrated “zone finding” and “triangulation” with adaptive beam forming allow the system to use only two references by switching nodes in and out of range. Pre-zone finding of a node permits proper geometry to be established for triangulation. This provides significantly improved tracking accuracy as compared to the triangulation only using three references. Also, narrow zone reduces beam width, thus significantly decreasing the tracking error but increases the zonal overhead. The PL&T performance analysis shows that by deploying interleaving Koay-Vaman (KV) transform coding technique for forward error correction and sample interleaving will achieves greater tracking accuracy using lower Eb/No in fast Doppler spread Rayleigh channel. The average estimated location tacking errorand average zonal overhead are significantly decreased under fast Doppler spread fading channel than slow Doppler spread fading channel.

Keywords: Dynamic Position Location Tracking, Location based Hash Scheme, Malicious Detection, Doppler Spread, Rayleigh Channel

Title of the Paper: Technologies used in Physical MAC-CPS and MAC-Security Layers of IEEE 802.16j Mobile Multi-Hop Relay (MMR) Networks

Authors: D. Satish Kumar, N. Nagarajan

Abstract: The IEEE 802.16 standard was formed in 1998 and approved in Dec-2001, to develop air interface standard for wireless broadband. The relay task group of IEEE 802.16 standard extended the IEEE 802.16e-standard with a new standard called IEEE 802.16j mobile multi-hop relay (MMR) standard. The IEEE 802.16j standard supports multi-hop relay operation was a relay station relay packets between base station and subscriber station. This article provides insight and understanding of the IEEE 802.16j mobile multi-hop relay (MMR) networks and describes some of the technologies used in physical, MAC-CPS and MAC-security layers of IEEE 802.16j wireless communication. The current Technologies of Physical and MAC layers are SOFDMA, Mobile IEEE 802.16j MMR channel encoding process, Relay station grouping and Messages, Ideal mode operation, Paging and Location management, Privacy Key Management protocol, IEEE 802.16j MMR physical layer security, comparison of WIMAX OFDM, OFDMA and SOFDMA, Up-link Sub Frame: down link Sub Frame, IEEE 802.16 Protocol Stack, Privacy and Key Management Protocol and authorization. We have described completely about all the above technologies in this article.

Keywords: IEEE 802.16j MMR physical layer security, IEEE 802.16J MMR OFDM, Protocol Stack, Privacy and Key Management Protocol

Title of the Paper: Efficient Hardware Implementation of Advanced Soft Information-Set Decoders in FPGAs

Authors: R. P. Jasinski, W. Godoy Jr., A. Gortan, S. B. L. França, V. A. Pedroni

Abstract: This paper has four main goals: (i) to describe in detail a new architecture to implement soft-decision, information-set-based decoders purely in hardware; (ii) to investigate the effects of quantization of the received word on the decoder performance, calculating the minimum number of bits that should be adopted; (iii) to present a strategy for optimizing the choice of candidate codewords, allowing the selection of a small set with a very high probability of containing the best candidate; and (iv) to present a new acceptance criterion that is both highly efficient and well-suited for hardware implementations.The proposed architecture can be used to implement any linear block decoder and is shown to be highly area-efficient, with the C(48,24,12) code occupying only 20% of the smallest FPGA in the Stratix IV family. It is also shown that there is very little to gain by using more than 3 quantization bits, and that sets as small as 3% of all possible values suffice to obtain essentially the same results as true MLD. The presented acceptance criterion reduces in 96.8% the number of candidates that must be evaluated for the C(24,12,8) code, with performance difference relative to the Taipale-Pursley criterion never larger than 12%.

Keywords: Block codes, error correcting codes, information set, decoder, hardware, FPGA

Title of the Paper: Performance Evaluation of Voice-Data Integrated Traffic in IEEE 802.11 and IEEE 802.16e WLAN

Authors: Anupam Roy, Md. Imdadul Islam, M. R. Amin

Abstract: With the advent of 4G mobile communication system the traffic of wired and wireless network becomes voice/video- data integrated service. In this paper traffic model of Markov Modulated Poisson Process (MMPP) is applied for bursty traffic of Wireless LAN (WLAN), especially in IEEE 802.11 WLAN, known as WiFi, and IEEE 802.16e WLAN is known as WiMAX. Traffic of both networks is heavily affected by the fading of wireless channel. The traffic parameters of IEEE 802.11 WLAN are evaluated using Giuseppe Bianchi state transition chain. The profile of probability of idle condition, the probability of one successful transmission and the probability of collision is shown against the number of users. The packet blocking probability and throughput of WLAN are observed varying packet arrival rate. In this paper, a mathematical model of VoIP traffic over wireless channel under IEEE 802.16e WLAN is also analyzed under Rayleigh and Nakagami-m fading cases with the help of MMPP and discrete time Markov chain (DTMC) model. Finally, mean delay of both wired and wireless LAN are compared.

Keywords: Voice-data integrated service, MMPP, DTMC, Rayleigh fading, Nakagami-m fading, VoIP

Title of the Paper: An Efficient Data Redundancy Reduction Technique with Conjugative Sleep Scheduling for Sensed Data Aggregators in Sensor Networks

Authors: K. P. Sampoornam, K. Rameshwaran

Abstract: An Efficient Data Redundancy Reduction (EDRR) scheme extending the life time of sensor nodes on wireless sensor networks has been proposed in this paper. Normally, in Wireless Sensor Networks (WSN), more energy is needed for transmitting data. In our earlier work, conjugative sleep scheduling scheme with Connected Dominating Set (CDS) for parent selection has been proposed. Whenever a sensor node fails or a new node is added to the network, the conjugative scheduling scheme evaluates the route maintenance algorithm. Remaining power levels of nodes have been examined in order to increase the network lifetime. This proposed work integrates conjugative sleep scheduler scheme with data redundancy reduction scheme. This energy efficient redundancy reduction scheme basically utilizes Differential Pulse Code Modulation (DPCM) technique. Rake receiver model data aggregation is adopted for aggregating the data from various sensor nodes. Finally, the performance of EDRR scheme is compared with existing energy efficient protocols. Based on extensive numerical experiments, the proposed scheme is evaluated in terms of Throughput, Energy Drain Rate, Power Consumption and Network life time.

Keywords: Sensor networks, Connected Dominating Set, Sleep Scheduling scheme, Data Aggregation, Redundancy Reduction, Power Consumption

Issue 8, Volume 12, August 2013

Title of the Paper: MANET Routing Protocols for Real-Time Multimedia Applications

Authors: Ghulam Yasin, Syed Fakhar Abbas, S. R. Chaudhry

Abstract: Mobile ad hoc network (MANET) is a self-directed system of mobile devices connected by wireless links. The node in MANETs moves in the region and modifies its locations by creating infrastructure less network without intervention of any network administrator. Varity of routing protocol for ad hoc network are probable. The main focus behind is to save resources (bandwidth) while using routing protocols. While deploying MANETs, a number of challenges involve like network scalability, Quality of services (QoS), energy utilization, security, privacy measures, bandwidth optimization and dynamic topology etc. In this paper an effort has been made to compare the performance of different routing protocols using multimedia application (video traffic). Protocols which are being analyzed in this paper are: AODV, DSR TORA and OLSR. The performance parameter includes Data Dropped, Delay, Load, Media Access Delay, Retransmission attempt and throughput.


Title of the Paper: Cooperative Multi-Antenna Relaying in Fixed Hybrid Relay Networks

Authors: Chanchal Kumar De, Sumit Kundu

Abstract: Co-operative communication using relays can achieve spatial diversity, which improves the link quality in a wireless network. In this paper, the performance of an infrastructure based multi-antenna adaptive decode-and-forward cooperative relay network in presence of a m-Nakagami fading channel using Low Density Parity check (LDPC) code has been investigated. The bit error probability (BER) and outage probability performance has been evaluated, when received signals are coherently combined at both the relays with multi-antenna and destination using Selection Combining (SC) and Maximal Ratio Combining (MRC) schemes respectively. The effects of number of relay antennas (L) and number of relays on the system performance have been studied. The impact of decoding threshold and „m‟ parameter on bit error rate (BER) and outage probability have also been evaluated. Further a tradeoff between relay antennas and number of relay is also indicated.

Keywords: Low Density Parity check (LDPC) code, Amplify and forward (AD), decode and forward (DF), adaptive decode and forward (ADF), BER, outage probability, Log- likelihood ratio (LLR), end-to-end (E2E)

Title of the Paper: Title Quality of Service Study for Single and Semi layer Interconnection Networks with Relaxing Blocking

Authors: Eleftherios Stergiou

Abstract: Performance evaluation, using both analytical and simulation models, of multistage priority interconnection networks with a single layer or more layers is presented. The configurations of the networks under study apply a conflict drop resolution strategy. Our analytical models are based on a more realistic assumption. A new analysis is given and is verified by simulation results. In single network configuration, it is shown quantitatively that the high priority packets are serviced better than the low priority ones. The proposed architecture’s performance is subsequently analysed under the uniform traffic condition, considering various offered loads, buffer-lengths, and network sizes. We demonstrate and quantify the improvements in the performance of single or semi-layer multistage fabrics stemming from the introduction of priorities in terms of throughput and packet delay. These performance measures can be valuable assets for designers of parallel multiprocessor systems and networks in order to minimize the overall deployment costs and deliver efficient systems.

Keywords: Multistage interconnection networks; analytical model; performance analysis; relaxing blocking; multilayer MINs; throughput; drop blocking

Title of the Paper: Efficient Hardware Implementation of Advanced Soft Information-Set Decoders in FPGAs

Authors: R. P. Jasinski, W. Godoy Jr., A. Gortan, S. B. L. França, V. A. Pedroni

Abstract: This paper has four main goals: (i) to describe in detail a new architecture to implement soft-decision, information-set-based decoders purely in hardware; (ii) to investigate the effects of quantization of the received word on the decoder performance, calculating the minimum number of bits that should be adopted; (iii) to present a strategy for optimizing the choice of candidate codewords, allowing the selection of a small set with a very high probability of containing the best candidate; and (iv) to present a new acceptance criterion that is both highly efficient and well-suited for hardware implementations. The proposed architecture can be used to implement any linear block decoder and is shown to be highly area-efficient, with the C(48,24,12) code occupying only 20% of the smallest FPGA in the Stratix IV family. It is also shown that there is very little to gain by using more than 3 quantization bits, and that sets as small as 3% of all possible values suffice to obtain essentially the same results as true MLD. The presented acceptance criterion reduces in 96.8% the number of candidates that must be evaluated for the C(24,12,8) code, with performance difference relative to the Taipale-Pursley criterion never larger than 12%.

Keywords: Block codes, error correcting codes, information set, decoder, hardware, FPGA

Title of the Paper: Effect of Various CODEC Parameters on the Performance of Modified Max-Log-MAP Turbo Decoding Algorithm

Authors: R. Krishnamoorthy, N. S. Pradeep, V. Aarthi

Abstract: Turbo decoder uses any one of the decoding algorithms, Maximum A posteriori Probability (MAP), or Soft Output Viterbi Algorithm(SOVA) because it produces error correction near to Shannon’s limit .The Max-Log-MAP is a Soft Input Soft Output (SISO) algorithm, which determines the probability of most likely path through the trellis and hence it gives sub optimal performance compared to Log-MAP algorithm. A simple but effective technique to improve the performance of Max-Log-MAP (MLMAP) algorithm is to scale the extrinsic information exchanged between two decoders using appropriate Scaling Factors (SF). Modified Max-Log-MAP (M-MLMAP) algorithm is achieved by fixing an arbitrary SF for inner decoder S2 and an optimized SF for the outer decoder S1. This paper presents the performance analysis for the Modified Max-Log-MAP decoding algorithm by optimizing the scaling factor S1 to achieve low Bit Error Rate (BER). The performance of various scaling factors is compared and optimized scaling factor is obtained, which is an empirical value. Appropriate mathematical relationship between scaling factor and Eb/N0 is also proposed. The effect of the proposed algorithm for a range of CODEC parameters is investigated in a systematic fashion, in order to gauge their performance ramifications. The use of an emphatically determined optimal scaling factor improved the performance of MLMAP decoding algorithm in terms of BER. The proposed M-MLMAP algorithm showed a gain of 0.75dB over MLMAP algorithm at BER of 2x10-5 for fading channel.

Keywords: BER, Log-MAP, Max-Log-MAP, Scaling Factor, Turbo codes

Issue 9, Volume 12, September 2013

Title of the Paper: Corona Sensor Cell based Deployment for Multiple-Sink Wireless Sensor Networks

Authors: Jyh-Horng Wen, Cheng-Chih Yang, Cheng-Min Lin, Yung-Fa Huang

Abstract: Wireless sensor network (WSN) scalability and energy-efficiency issues remain an interesting research problem. This paper presents a multiple-sink deployment scheme for large-scale WSNs. An 8-rings Corona style sensor network is regarded as a Corona Sensor Cell (CSC) based on coarse-grain location awareness for energy-efficiency consideration. The overall task includes nodes training and data delivery. Let a specific WSN consists of N CSCs. In training protocol periodic, the costing ratio for the traditional single-sink scheme compares with our proposed multi-sink scheme is approximately0.7 N . In data delivery period, the sensor node power consumption ratio for the traditional single-sink scheme compares with our proposed multisink scheme is approximately 0.9 N . Thus, the proposed scheme is more energy efficiency than the traditional scheme.

Keywords: Wireless sensor network, Coarse-grain location aware, Corona sensor cell, Training protocol, Multiple-sink

Title of the Paper: Interference Cancellation in Multi Stage Multi-User Detection in DS-CDMA System using Hybrid Technique

Authors: J. Ravindrababu, E. V. Krishna Rao, Y. Raja Rao

Abstract: Direct Sequence Code Division Multiple Access (DS-CDMA) system is suffers from Multiple Access Interference (MAI). Multi-User Detection schemes were introduced to detect the users’ data in presence of MAI. In this paper, we proposed a novel method is called Hybrid Interference cancellation (HIC) scheme. It consists of the combination of subtracting and partial parallel interference cancellation schemes. Here considering decorrelator for first stage instead of matched filter. Partial PIC is based on multiplying the amplitude estimates with a partial cancellation factor. Subtracting PIC exploits the multi stage character of PIC to avoid unnecessary double calculations of certain terms in consecutive stages. The hybrid PIC scheme to achieve performance improvement and complexity reduction compared to conventional PIC in multistage multiuser environment.

Keywords: Multi-user detection, MAI, Matched filter, Decorrelator, DS-CDMA, PIC. kasami odd sequence

Title of the Paper: Redundancy-Based Semi-Reliable Packet Transmission in Wireless Visual Sensor Networks Exploiting the Sensing Relevancies of Source Nodes

Authors: Daniel G. Costa, Luiz Affonso Guedes, Francisco Vasques, Paulo Portugal

Abstract: Visual data monitoring in wireless sensor networks can significantly enrich a large set of surveillance and general purpose monitoring applications. However, transmission of image snapshots or video streams can rapidly deplete the energy resources of the deployed nodes, turning energy efficiency into a major optimization issue. During wireless transmissions, packets can be corrupted directly affecting the monitoring quality of the applications. One reasonable way to reduce quality loss is the transmission of redundant packets for higher error resilience, but additional packet transmissions may incur in undesirable energy consumption. Frequently, some monitoring quality loss may be tolerated since visual information retrieved from source nodes may have different relevance for the applications, according to the monitoring requirements and the current sensors’ poses and fields of view. In such way, we propose that only high-relevant source nodes will transmit redundant packets, assuring error resilience only for the most relevant visual data for the monitoring application. Doing so, energy is saved over the network when fewer packets are transmitted in average, potentially enlarging the network lifetime with reduced impact to the overall monitoring quality.

Keywords: Packet-level redundancy; wireless visual sensor networks; semi-reliable transmission; sensing relevance of source nodes

Title of the Paper: Performance Study of Diversity Combining Techniques for Error-floor Reduction in Fast Fading Channels

Authors: Yazid Khattabi, Haythem Bany Salameh, Mohammad Al-Ibrahim

Abstract: We investigates the effect of mobile speed, channel estimation rate, diversity order on performance degradation due to error floor in a mobile Single-Input-Multiple-Output (SIMO) wireless communication system. Each diversity channel is assumed to be fast Rayleigh fading process, which is modeled as a first order autoregressive process. Diversity channels are assumed to be independent and identically distributed (i.i.d) with identical channel correlation parameters and channel estimation rates at each receiving antenna. Two receiving diversity combining techniques are used: maximum ratio combining (MRC) and selection combining (SC), and two binary modulation schemes are considered: coherent PSK (BPSK) and differentially coherent PSK (BDPSK). The performance is investigated in terms of the overall average output received signal-to-noise-ratio (SNR) and bit error rate (BER). Closed-form expressions for the average received SNR and BER are derived. We show that these expressions are also applicable for slow fading scenarios. Numerical results demonstrate the negative affects of error floor on system performance under fast fading channels. For coherent detection, we show that increasing the channel estimation rate improves performance and reduces the error floor especially when higher diversity order is used. For differentially coherent detection, with low channel estimation rates, the results reveal that increasing diversity order reduces error floor compared to coherent detection. Our results also show that MRC provides better performance compared to SC irrespective of the value of the correlation parameter, the channel estimation rate, and the used modulation scheme.

Keywords: Fast fading; Error floor, SIMO, BPSK

Title of the Paper: Modeling Fluctuations in the Quasi-static Approach Describing the Temporal Evolution of Retry Traffic

Authors: Kohei Watabe, Masaki Aida

Abstract: In previous work, we introduced the quasi-static retry traffic model, which describes the behavior of retry traffic generated by users who are impatient when waiting for a response from the system. In other words, the model describes interactions between users and the system. This interaction can be described in a simple form if it is assumed that the system offers infinitely fast (ideal) processing. Moreover, we proposed a performance evaluation technique called the quasi-static approach that replicates the temporal evaluation of traffic in finite speed (real-world) systems. In the quasi-static approach, the difference between the behavior of the ideal system and that of the real-world system is expressed as stochastic fluctuation. In this paper, we model the fluctuation for exactly replicating the behavior of retry traffic caused by user impatience using the quasi-static approach, and show the validity of an evaluation of the quasi-static approach by comparing the results of the quasi-static approach and that of conventional Monte Carlo simulation, in M/M/1- and M/M/s-based systems with retry traffic.

Keywords: Retry traffic, Quasi-static approach, Fluctuations, Traffic model, Queueing system, Langevin equation, Fokker-Plank equation

Title of the Paper: An Efficient Data Redundancy Reduction Technique with Conjugative Sleep Scheduling for Sensed Data Aggregators in Sensor Networks

Authors: K. P. Sampoornam, K. Rameshwaran

Abstract: An Efficient Data Redundancy Reduction (EDRR) scheme extending the life time of sensor nodes on wireless sensor networks has been proposed in this paper. Normally, in Wireless Sensor Networks (WSN), more energy is needed for transmitting data. In our earlier work, conjugative sleep scheduling scheme with Connected Dominating Set (CDS) for parent selection has been proposed. Whenever a sensor node fails or a new node is added to the network, the conjugative scheduling scheme evaluates the route maintenance algorithm. Remaining power levels of nodes have been examined in order to increase the network lifetime. This proposed work integrates conjugative sleep scheduler scheme with data redundancy reduction scheme. This energy efficient redundancy reduction scheme basically utilizes Differential Pulse Code Modulation (DPCM) technique. Rake receiver model data aggregation is adopted for aggregating the data from various sensor nodes. Finally, the performance of EDRR scheme is compared with existing energy efficient protocols. Based on extensive numerical experiments, the proposed scheme is evaluated in terms of Throughput, Energy Drain Rate, Power Consumption and Network life time.

Keywords: Sensor networks, Connected Dominating Set, Sleep Scheduling scheme, Data Aggregation, Redundancy Reduction, Power Consumption

Issue 10, Volume 12, October 2013

Title of the Paper: Evaluation of the μController Networks Communication for EtherCAT Process Data Interface

Authors: Li Jiang, Mingxin Hou, Fanshao Wei, Minghe Jin, Hong Liu, Zhaopeng Chen

Abstract: According to the EtherCAT process data interface networks system designs, we determined that the Synchronous and Asynchronous µController scheme evaluations based on the FPGA state machine algorithm. The present study focuses on the Schematic of µController interconnection between FPGA and ESC based on the VHDL state machine algorithm, which includes state machine programs. In addition, the performance of the Synchronous and Asynchronous µController was verified through numerical simulations. Furthermore, we found the simulations gave further evidence that the 16 bits synchronous and Asynchronous µController signals can satisfy the two write access and a read access requirements for the EtherCAT networks communication. Finally, the results include the positive and negative aspects of the Synchronous and Asynchronous µController networks communication, and the comparison the results of the Synchronous, Asynchronous and SPI communication evaluations done by the researchers.

Keywords: Synchronous network communication; Asynchronous network communication; EtherCAT; FPGA State Machine; μController

Title of the Paper: Relay-Assisted Distributed Hybrid MIMO Transceiver with Information Exchange Errors for Cooperative Networks

Authors: Shu-Ming Tseng

Abstract: For non-relaying cooperative networks, the previous work proposed a distributed space-time block code (STBC) scheme considering information exchange errors in two-user cooperative networks. We propose a distributed Hybrid multiple-input multiple-output (MIMO) Transceiver scheme (HMT) considering information exchange errors in three-user cooperative networks. For relaying cooperative networks, the previous work also proposed an un-coded demodulation and forward relay and considering demodulation errors in the relay in two-user cooperative networks. We propose the relay-assisted distributed HMT scheme considering information exchange errors in 3-user cooperative networks, the differences are that our scheme has 3x2 HMT with transmit antenna selection in source-to-relay, source-to-destination, and relay-to-destination links, but the previous scheme has the 2x2 un-coded schemes in these three links. For both non-relaying and relaying scenarios, the simulation results show the proposed schemes have lower bit error rate (BER) than the previous schemes at the same 4 bits/sec/Hz transmission rate.

Keywords: Hybrid STBC, cooperative networks, distributed coding, demodulation and forward relay

Title of the Paper: Channel Estimation in DS-CDMA System based on Quantum Constraints

Authors: S. Karthikeyan, P. Ganesh Kumar, S. Sasikumar

Abstract: A system model for DS-CDMA (Direct Sequence Code Division Multiple Access) is described in its basic form and performance measure based on Mean Square Error (MSE) and Symbol Error Rate (SER) under Additive White Gaussian Noise is performed. For measuring the performance of DS-CDMA receivers, the channel estimate plays for a crucial role and hence the channel estimation for DS-CDMA is considered. We describe the channel estimation based on the time domain channel statistics, using a general model for a slow fading channel. The investigation on the performance of Least Square estimator (LS) and Minimum Mean Square Error estimator (MMSE) in asynchronous DS-CDMA linear receiver is studied. The investigation studies the effect of MSE and SER with different modulation scheme employed in it and their analysis of modulated effect are taken into comparison. The result shows that the proposed MMSE channel estimator, exhibiting the best trade-off between LS and MMSE estimation error components.

Keywords: Orthogonality, Gaussian Channel, Covariance, Spread Spectrum, Mean Square Error

Title of the Paper: LTE Optimal Transmission Mode Selection Guidelines over MIMO Channels

Authors: Illa Kolani, Jie Zhang

Abstract: In LTE /LTE -advanced standards, the physical layer is mapped into multiple transmission modes(TM) and each TM should be dynamically selected depending on the time-varying MIMO channel. Besides the single antenna SISO transmission (TM1), multielement antenna (MIMO) technology such as Open Loop Spatial Multiplexing (OLSM) and Close Loop Spatial Multiplexing (CLSM) transmission are also specified by the 3GPP standard for LTE downlink transmission. In this paper, on the basis of study upon interaction between MIMO channel correlations through the correlation metric in terms of the amount of correlation with MIMO Diversity-Multiplexing Trade-off (DMT), we propose an optimal transmission mode switching method by delimiting wisely guards intervals of different correlation environment levels.

Keywords: LTE, MIMO, Spatial Multiplexing, OLSM, DMT, Amount of Correlation, Transmission Mode, OSTBC

Title of the Paper: Towards Realistic Performance Evaluation of Delay Tolerant Network

Authors: Neelam Malik, Shailender Gupta, Bharat Bhushan

Abstract: Delay Tolerant Network (DTN) is a type of wireless ad hoc network in which route is established between a pair of nodes in spite of having long delays and frequent route ruptures. To ensure successful communication in such an environment a robust routing protocol is used the performance of which depends upon various factors such as transmission range, processing capability, transmission delays, bandwidth and the environment. Many researchers have evaluated the performance of routing protocol in an idealistic environment and only few have made an effort to evaluate its performance for realistic environment. This paper is an effort to evaluate the efficacy of DTN in realistic as well as idealistic conditions by designing a simulator in MATLAB-7.0. To make the scenario realistic, obstacles of different shapes, types and numbers were introduced in the simulation region. The results show that the performance of routing protocol vary significantly by changing the environment i.e. the results for idealistic scenario cannot be applied for realistic scenario.

Keywords: Routing, Realistic Environment, Simulation

Issue 11, Volume 12, November 2013

Title of the Paper: RSS based Localization of Sensor Nodes by Learning Movement Model

Authors: R. Arthi, P. Devaraj, K. Murugan

Abstract: Node Localization in Wireless Sensor Networks (WSNs) is widely used in many applications. Localization uses particle filter that provides higher network traffic due to continuous updates, which leads to high power consumption. The article presents a range-based localization for Mobile Nodes (MN) that builds up on Hidden Markov Model (HMM) algorithm. The proposed work is based on MN and the state is hidden in the Received Signal Strength (RSS) for outdoor applications. Hidden states uses explicit knowledge of the observation probability obtained from two-ray ground propagation model. HMM correlates these observations to predict the hidden states. The state transition and the observation of HMM help to estimate the most probable state sequence and the last state obtained is the predicted location. This work uses various mobility models for the movement of nodes. Varying the transmission range effectively controls the network connectivity. Results from simulation study have revealed the possible reduction of network traffic and power consumption with less estimation error. In addition, this work provides an efficient confidence interval for the estimation error.

Keywords: Estimation Error, Hidden Markov Model, Localization, Mobile Nodes, Received Signal Strength, State Estimation, Wireless Sensor Networks

Title of the Paper: Opt-TDMA/DCR: Optimized TDMA Deterministic Collision Resolution Approach for Hard Real-Time Mobile Ad hoc Networks

Authors: Sofiane Ouni, Jihen Bokri, Farouk Kamoun

Abstract: A new kind of critical applications, using Mobile Ad hoc networks, has appeared. These applications such as vehicular or robotic ones are called Hard Real Time Applications. Their major requirement is to respect the real time constraints especially the deadlines on the treatment and the communication delay. However, providing real-time communication, with predictable delay, is a challenge because of the Ad Hoc network features, particularly the node’s mobility. In this paper, we propose a new medium access protocol (which we call: Opt-TDMA/DCR) for these hard real time applications. Our approach consists in a distributed protocol considering dynamic network topology with mobile nodes. It is based on the TDMA protocol which we optimize by reducing the TDMA frame size. The reduction of the slot number of the TDMA frame is made with the “modulo” function which is used to select slots for transmission. However, this will probably lead to collisions between nodes selecting the same slots. Hence, a deterministic collision resolution procedure will then be applied to make communication with distinct slots. In order to verify the respect of real time constraints by our protocol, we made a communication delay analysis in the worst case and in the average case.

Keywords: Mobile Ad Hoc networks, hard real time, TDMA, deterministic medium access protocol, communication delay

Title of the Paper: Trustworthy Position Based Routing to Mitigate against the Malicious Attacks to Signifies Secured Data Packet using Geographic Routing Protocol in MANET

Authors: Sudhakar Sengan, S. Chenthur Pandian

Abstract: A mobile ad hoc network (MANET) is a dynamic wireless network that can be formed without any preexisting infrastructure in which each node can act as a router. Instead of using topology based routing protocolto prefer Geographic Routing Protocol (GRP) become scalability and to improve more successive rate and also reducing the overhead. Here proposed a novel secure position-based routing protocol, it takes dynamic pseudo identifiers instead of its real identity in advertising its position. Though the MANET hasdifferent malicious attacks such as flooding, black hole and wormhole etc., because of simulation studies demonstrate that the networks with 15% malicious nodes show significant performance degradation. In order to present secure communication and transmitting recommended that this tactics is actually asymmetric encryption technique. Simulation is focused to take measurements were taken in the light of throughput, end-to-end delay and network load and using the modified asymmetric cryptographic system to improve the through put and reduced the packet drop against malicious attacks. Simulation is done in Optimized Network Engineering Tool (OPNET).

Keywords: MANET, Geographic Routing Protocols, Cryptography, Performance, Malicious Attacks

Title of the Paper: Performance Analysis of Spatial Modulation over Weibull Fading Channels

Authors: Ahmad M. Alshamali, Mohammed S. Aloqlah

Abstract: Ascertaining the importance of the recently proposed spatial modulation, we study its performance in Weibull multipath fading channels. Closed form integral expressions for calculating the symbol error rate of spatial modulation (SM) in independent, not necessarily identical Weibull fading channels are derived. Simulation and the analytical results, considering different transmission scenarios, are very close over a wide range of signal-to-noise ratio (SNR) values.

Keywords: Spatial modulation, Weibull fading, symbol error rate

Issue 12, Volume 12, December 2013

Title of the Paper: Recovering Weak Signal Using Nakagami Fading Wireless Channel with Multiuser Diversity

Authors: K. Jayanthi, V. P. Arunachalam, C. Vasanthanayaki

Abstract: Propagation of new wireless technologies has regenerated an interest on the digital modulation system, analysis and implementation of suboptimal receiver designs that provide poor performance when the order of diversity is large. In this proposed system propose a new creation for causing the Nakagami Fading channel(NFC) which possess random and different fading figure m for each sub channel with Multiuser diversity is used to producing an acceptable average Signal to Noise Ratio(SNR) and best statistical reducing outage probability(Pout) or Bit Error Rate (BER) of multipath fading effect. The diversity is produced by the depolarization of the transmitted signal by reflection, diffraction, and scattering in the channel of Nakagami Fading channels. The result of this proposed system, a novel simple and high efficient generation method is developed to scrutinize an excellent accuracy in wireless media.

Keywords: Multipath Fading, Nakagami Fading Channel, Fading Figure, Multiuser Diversity, Outage Probability

Title of the Paper: A Novel Method of Walsh-Hadamard Code Generation Using Reconfigurable Lattice filter and Its application in DS-CDMA System

Authors: G. Suchitra, M. L. Valarmathi

Abstract: Walsh Hadamard codes are widely used as signature codes in the current wireless standards such as IS-95 CDMA, WCDMA, CDMA2000, and image transform applications. It is also used in conjunction with error correction algorithms for Reed-Muller codes and in dyadic invariant signal processing. In this paper, a novel method of generating Walsh Hadamard(WH) codes using lattice filter is proposed. The obtained results concur with the properties of WH code. The entire WH code set can be generated by changing the reflection coefficients without modifying the filter structure. This feature ensures reconfigurability and enables them to be used in software radio. Moreover, this reconfigurable structure can be used as a matched filter for multiuser detection in Direct Sequence Code division Multiple Access System (DS-CDMA). BER performance of a DS-CDMA system employing a correlator receiver and the proposed matched filter receiver for despreading is simulated in an AWGN channel and flat fading Rayleigh channel. Simulation results showing the generation of WH codes from the autoregressive model of first order Gauss-Markov process is also obtained.

Keywords: Software defined radio, Walsh Hadamard codes, Lattice filter, Matched filter, Autoregressive model, Gauss-Markov process

Title of the Paper: Peak-to-Average Power Ratio Reduction of OFDM signals Using Improved PTS Scheme with Low Computational Complexity

Authors: Alok Joshi, Davinder S. Saini

Abstract: In wireless communication, parallel transmission of symbols using multi carriers is applied to achieve high efficiency in terms of throughput and better transmission quality. Orthogonal Frequency Division Multiplexing (OFDM) is one of the techniques for parallel transmission. It effectively mitigates the effect on performance due to Intersymbol Interference and delay spread caused by wireless medium. However high peak to average power ratio (PAPR) is a major demerit of OFDM system. High PAPR leads to increased complexity of circuit and reduced efficiency of RF amplifier. Partial Transmit Sequence (PTS) is one of the most promising techniques for PAPR reduction. In conventional PTS scheme the computation of optimal phase factors necessitates exhaustive searching of all possible and allowable phase factors, this leads to exponential increase of computation complexity in terms of complex additions and multiplications as number of subblock increases. In this paper by exploiting correlation among various candidate phase factors a novel scheme is proposed here which reduces the computation complexity by tremendous margin and at the same time maintaining same PAPR reduction as conventional PTS scheme. OFDM signal Implemented here complies with IEEE 802.11 a standard.

Keywords: OFDM, PAPR, PTS, Complex multiplication and addition, Phase weighting

Title of the Paper: Design of Tri-Band Bandpass Filter Based On Quad-Sections SIR Resonator for Wireless Applications

Authors: Emad S. Ahmed

Abstract: In this article, a new tri-band bandpass filter, operating at 2-2.6 GHz, 3.5-4.5 GHz and 5-5.8 GHz for GSM, WiMAX and WLAN application is proposed. Two quad sections SIR resonators and corresponding feeding structures are introduced to enhance the tuneable range of operating frequencies. Using source/load coupling can realize two controllable transmission zeros around each operating band. The filter is analyzed and solved in terms of the transmission line model using finite element method (FEM) and results are refined by full-wave simulator CST Microwave Studio 2009 and SONNET Version.11. The comparison between magnitudes of s-parameters simulation results with SONNET and CST Microwave Studio simulators are also presented. The results show a good match between two simulation results with different commercial software for the proposed bandpass filter. The desired operating bands are covered by the response of the different software’s.

Keywords: SIR resonator, microstrip bandpass filter, WLAN and WiMAX applications, tri-band filter, CST Microwave Studio, SONNET, Quad sections resonators

Title of the Paper: Dynamic Energy Efficient Topology for Wireless Ad Hoc Sensor Networks

Authors: N. Thangadurai, R. Dhanasekaran, R. D. Karthika

Abstract: Wireless Sensor Ad hoc Networks (WASNs) are self organizing, self-configuring and multi-hop wireless networks, in which each node communicates with other nodes directly or indirectly through intermediate nodes without any infrastructure. Besides these characteristics challenges like limited energy, dynamic topology, low bandwidth and security exists. The arrangement of nodes in WASN is called topology which changes dynamically with respect to time and mobility of nodes. Energy conservation is a major challenge because of the limited battery resource. In order to conserve energy in the network layer many techniques were used. These techniques can be classified mainly into two categories. The first technique is making small number of nodes awake to transfer bulk amount of data and to maintain the network connectivity and making the remaining nodes to be in sleep mode to conserve energy. This technique is effective for low traffic conditions. In the second technique, topology in the network is controlled by power control technique. This technique is effective for high data traffic. To conserve energy in an efficient manner, an Energy Efficient Traffic Topology dynamically adjusts network topology for various network traffic conditions in WASN either in low traffic or high traffic is proposed here. And the proposed protocol is stimulated by using AODV as routing protocol using network simulator ns2.34 and compared with AODV and DSR [1,2]. The simulation results revealed that the proposed scheme performs well in terms of energy, delay, delivery ratio and mobility and number of nodes alive.

Keywords: AODV, DSR, Energy Efficient Topology, Routing Algorithm, WASN

Title of the Paper: Performance of LDPC-Coded APSK-Modulation for Wireless USB

Authors: C. T. Manimegalai, R. Kumar

Abstract: The creation of Ultra-Wideband (UWB) radio platform has allowed the development of high bit-rate Wireless-USB offering High Definition video streaming. Quadrature Phase Shift Keying (QPSK) and Dual Carrier Modulation (DCM) are the current modulation schemes used for Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) in the ECMA-368 defined UWB radio platform. ECMA-368 offers up to 480 Mb/s instantaneous bit rate to the Medium Access Control (MAC) layer to enable the high-rate transmission, but depending on radio channel conditions dropped packets unfortunately result in a lower throughput. This paper presents a higher data rate Coded modulation scheme that fits within the configuration of the current standard to increase the system throughput by achieving 960 Mb/s (reliable to 3 meters) thus maintaining the high rate USB throughput even with a moderate level of dropped packets. The system performance for LDPC coded 32-APSKmodulation is simulated in realistic multipath environments.

Keywords: APSK (Amplitude Phase Shift Key), Multi band-Orthogonal frequency-division multiplexing (MB-OFDM), ultra-wideband (UWB), wireless personal area networks (WPAN)

Title of the Paper: Design and Analysis of Miniaturized Multiband High Frequency Antenna for K and Ka Band Applications

Authors: P. Jothilakshmi, S. Raju

Abstract: This paper proposes the design and analysis of co-axial continuous transverse stub multiband antenna (CCTS) for multiple high frequency Applications. Coaxial continuous transverse stub antenna is used to operate on multiple frequency bands with small size and low cost. This proposed antenna consists of two stubs, arranged longitudinally to form a waveguide skeleton like structure. The advantages of CCTS antenna are used to produce omnidirectional radiation pattern in the horizontal plane. This antenna can radiate for the frequency range of 24.5 GHz to 35 GHz which is suitable for portion of K band and Ka band wireless applications. This proposed structure produces very good radiation pattern in both vertical and horizontal plane with minimum acceptable return loss. The simulation software used in this design is CST Microwave Studio and MATLAB.

Keywords: Multiband, Stub, Continuous Transverse Stub, Antenna Array, S-parameter, Radiation Pattern, VSWR

Title of the Paper: Enhancing Future Wireless Systems through Advanced Physical Layer Mechanisms

Authors: K. Thilagam, K. Jayanthi

Abstract: In recent years, the rapid growth of new-generation wireless networks has spurred a research thrust in cooperative communication and it is a powerful physical layer technique to combat fading in wireless relaying scenario. Recently, chaos based communication with its excellent features has been proved to be an appropriate choice for the emerging wireless networks. Different chaos based modulation schemes has been analysed with immense literature, of which the Code Shifted-Quadrature Chaos shift Keying (CS-QCSK) modulation technique with its code domain approach provides better BER performance and spectral efficiency. In the coding scenario, Reduced Golden Ratio-Golden codes (RGR-GC) has been proved to exhibit better Bit Error Rate (BER) performance with less complexity than any other space time block codes in [29]. The forementioned coding scheme (RGR-GC) and the modulation scheme (CS-QCSK) are concatenated to obtain a suitable combination approach (RGR-GC_CS-QCSK) which enhances the performance significantly has been discussed in [30]. This paper aims to test the suitability of proposed technique in a cooperative relaying scenario. The single relay cooperative scenario consisting of source, relay and destination are considered with the Decode and forward (DF) protocol. The simulation results have validated the effectiveness of the proposed scheme by offering better BER performance, minimum outage probability and increased spectral efficiency compared to the non cooperative transmission method.

Keywords: Code Shifted-Quadrature Chaos shift Keying (CS-QCSK), Reduced Golden Ratio-Golden codes (RGR-GC), modified golden codes, Decode and forward (DF) protocol, single physical layer entity, cooperative communication

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