WSEAS Transactions on Communications
Print ISSN: 1109-2742
Volume 13, 2014
Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.
Volume 13, 2014
Title of the Paper: AN OFDM Platform for Wireless Systems Testing: Alamouti 2x1 MIMO Example
Authors: Manuel Violas, João Lourenço, Adão Silva, Atílio Gameiro
Abstract: In this paper, we present a real-time implementation of an OFDM hardware platform. The platform is based on HW blocks that can be put together to configure a wireless system based on OFDM modulation. The platform can be easily upgraded to test pre-coding cooperation algorithms. We evaluate the platform to implement a diversity Alamouti 2×1 MIMO scheme wireless system. The testbed is implemented using Field-Programmable Gate Array (FPGAs) through Xilinx System Generator for DSP. Blocks for time-domain synchronization and channel estimation are key components necessary in transmission system that require good time synchronization and channel estimation for efficient demodulation.
Keywords: OFDM; FPGA; Software Defined Radio (SDR), CFO, LTE
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #74, pp. 672-682
Title of the Paper: A Method for Parameter Extraction and Channel State Prediction in Mobile-to-Mobile Wireless Channels
Authors: Ramoni Adeogun
Abstract: This paper investigates the prediction of single input single output (SISO) narrowband multipath fading channels for mobile-to-mobile wireless communications. Using a statistical model for mobile to mobile urban and suburban channels, we derive a parametrized model and utilize the ESPRIT algorithm to extract the effective Doppler frequencies from noisy channel estimates. The parameter estimates are then used to forecast the mobile-to-mobile channel into the future. Using the Cramer Rao bound for function of parameters, a bound on the prediction error of M2M wireless channels is derived. Simulations were performed to evaluate the performance of the prediction scheme and comparison was made with the prediction of typical fixed to mobile channels and also with the derived bound. Results show that the performance of the scheme approaches the bound as the SNR increases.
Keywords: Multipath fading channels, mobile-to-mobile channel, parameter estimation, ESPRIT, channel estimation and prediction
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #73, pp. 665-671
Title of the Paper: The Use of Parametric Statistical Tests to Detect Network Traffic Anomalies on SDN Architectures
Authors: Paulo Pinto, Luis Pinto
Abstract: The workrealized in this paper as a twofold approach: by one side to present a proof-of-concept that illustrate the flexibility and ease of anomaly detection algorithm implementation on a SDN architecture accessing to the information (counters) existing on the controller; by other side to show the applicability of nonparametric statistics, Kendall’s W statistic, to detect network changes on SDN corresponding to possible DoS attacks.
Keywords: Architecture, Software Defined Networks, Denial of Service, Kendall, Parametric Statistics
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #72, pp. 659-664
Title of the Paper: Smart Traffic Light Junction Management Using Wireless Sensor Networks
Authors: Mario Collotta, Tullio Giuffre, Giovanni Pau, Gianfranco Scata
Abstract: In recent years, Wireless Sensor Networks (WSN) have been increasingly involved in Intelligent Transportation System (ITS) optimization, especially in dynamic management of signalized intersections. This paper discusses the state of art and shows an IEEE 802.15.4 network architecture to monitor vehicular traffic flows near to a traffic light. The architecture is characterized by an innovative algorithm in order to determine green times and phase sequence of traffic lights, based on measured values of traffic flows. The main aim of this work is to reduce the average waiting time. To confirm the validity of the proposed approach, some case studies have been considered and several simulations have been performed.
Keywords: Wireless Sensor Networks, Traffic Lights, Intelligent Transportation Systems, Real-Time Systems
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #71, pp. 648-658
Title of the Paper: Heuristic Multiuser Detectors: A DSP Implementation Perspective
Authors: Alex Miyamoto Mussi, Taufik Abrao
Abstract: This work investigates issues concerning the computational complexity of multiuser receivers in direct sequence code division multiple access (DS/CDMA) systems based on heuristic techniques and implemented on commercial platform for digital signal processing (DSP) (Texas TMS320C6713). The multiuser detection (MuD) algorithms which were implemented in baseband are based on the heuristic local search (LS) and simulated annealing (SA) approaches. Figures of merit regarding the bit error rate (BER) performance versus computational complexity trade-off are evaluated as a function of the system loading increasing (number of active users per processing gain); as a result, a methodology for the design and implementation of a baseband multiuser receiver structure using DSP platform is developed as well.
Keywords: DSP, DS/CDMA, MuD, heuristic algorithms, computational complexity, performance-complexity tradeoff
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #70, pp. 638-647
Title of the Paper: Pseudo Peak Suppression in Generating Range Profile with Multi-Carrier Chirp
Authors: Yang Chao, Zheng Lin, Bai Yunhao
Abstract: To ensure the reliability of transmission and prevent inter-carrier interference (ICI) between sub-bands, the sub-carrier frequency increment is usually greater than the bandwidth of sub-band for multi-carrier chirp. That will bring on false targets generated by pseudo peaks on High Resolution Range Profile (HRRP). At the presence of false targets, it is difficult to get the true position of target due to the serious influence on target detection. In this paper, the mechanism of pseudo peaks generation is analyzed and an algorithm is proposed to remove pseudo peaks while the image resolution is improved by Super-SVA, which reduces the echo pulse width. With the pulse width less than an unambiguous range, the HRRP without false targets can be obtained. With the analysis and simulation of single and multi-targets, the results indicate that this algorithm can effectively remove false targets caused by the pseudo peaks.
Keywords: Multi-carrier communications, pseudo peak, Super-SVA, HRRP, Target detection, Chirp signal
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #69, pp. 631-637
Title of the Paper: Level Crossing Rate of Ratio of Product of Two α-k-µ Random Variables and α-k-µ Random Variable
Authors: Dragana Krstić, Mihajlo Stefanović, Vladeta Milenković, Djoko Bandjur
Abstract: In this paper, the ratio of product of two α-k-µ random variables and α-k-µ random variable is analyzed. The closed form expression for average level crossing rate (LCR) of the ratio of product of two α-k-µ random variables and α-k-µ random variable is determined. The expression for level crossing rate of the ratio of product of two α-k-µ random variables and α-k-µ random variable can be used for calculation of average fade duration of wireless communication system operating over composite α-k-µ multipath fading environment in the presence of cochannel interference subjected to α-k-µ multipath fading. The α-k-µ distribution can be used to describe small scale signal envelope variations in non linear line-of-sight multipath fading environments.
Keywords: α-k-µ random variable, co-channel interference, level crossing rate (LCR), multipath fading, wireless communication systems
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #68, pp. 622-630
Title of the Paper: Adaptive Detection of Range-Spread Targets in Gaussian Noise Using the Generalized Detector
Authors: Vycheslav Tuzlukov
Abstract: In this paper, we address an adaptive detection of range-spread targets or targets embedded in Gaussian noise with unknown covariance matrix by the generalized detector (GD) based on the generalized approach to signal processing (GASP) in noise. We assume that cells or secondary data that are free of signal components are available. Those secondary data are supposed to process either the same covariance matrix or the same structure of the covariance matrix of the cells under test. In this context, under designing GD we use a twostep procedure. The criteria lead to receivers ensuring the constant false alarm rate (CFAR) property with respect to unknown quantities. A thorough performance assessment of the proposed detection strategies highlights that the two-step design procedure of decision-making rule in accordance with GASP is to be preferred with respect to the plain one. In fact, the proposed design procedure leads to GD that achieves significant improvement in detection performance under several situation of practical interest. For estimation purposes, we resort to a set of secondary data. In addition to the classical homogeneous scenario, we consider the case wherein the power value of primary and secondary data vectors is not the same. The design of adaptive detection algorithms based on GASP in the case of mismatch is a problem of primary concern for radar applications. We demonstrate that two-step design procedure based on GASP ensures minimal loss.
Keywords: Generalized detector, additive Gaussian noise, detection performance, constant false alarm rate (CFAR), generalized approach to signal processing (GASP), high resolution radar, signal-to-noise ratio (SNR)
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #67, pp. 606-621
Title of the Paper: Infrastructure to Vehicle Communications Using Inductive Loops
Authors: Răzvan Andrei Gheorghiu, Iulian Bădescu, Radu Serban Timnea
Abstract: Road safety is a worldwide issue. The constant increase of the number of vehicles and the more congested infrastructure lead to more traffic incidents. Infrastructure to vehicle communication is a way to improve traffic safety, by sending traffic information to vehicles, such as the colour the next traffic light will be when the car reaches the road junction. This approach may be useful also for autonomous vehicles that need all the data available in order to travel in a safe manner on the road network. In this article we shall analyse the possibility of sending information from the traffic management system to vehicles using one of the most common traffic detectors, the inductive loop.
Keywords: communications, I2V, wireless, WiFi, Bluetooth, Zigbee, DSRC, urban traffic, traffic management system, inductive loop
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #66, pp. 596-605
Title of the Paper: Large-Scale Industrial Company Alarm Receiving Centre Modernization Design
Authors: Jiri Sevcik, Malus Martin, Svoboda Petr
Abstract: Particular functional blocks of Large-Scale Alarm receiving Centre modernization Design creates core contribution of this research paper. In the introductory chapter the valid legislation and the resulting requirements for the design, location, construction, technical equipment, operations and personnel are described. Moreover, the methodology of evaluation of the Alarm receiving Centre quality is proposed and applied to the particular company. The particular modernization related to selected areas such as communication or ergonomic layout of the workplace is then specified on the basis of the evaluation results. Moreover, the design of particular renovations is provided, including appropriately chosen technology and manufacturer, respectively provider.
Keywords: Alarm Receiving Centre Design, Security Assessment, Evaluation, Modernization, Ergonomic
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #65, pp. 587-595
Title of the Paper: Application of Improved SSL in Data Security Transmission of Mobile Database System
Authors: Ruifeng Wang, Xiaohua Zhang, Dechao Xu
Abstract: The existing SSL (Secure Socket Layer) protocol which mobile database system is using has many drawbacks, such as large amount of communication, computational complexity of encryption algorithm and the workload imbalance. In order to solve these problems, the paper proposes an improved SSL protocol. It decomposes the private key into independent elements which reducing the computational complexity and implementing parallel computing, at the same time it put part of decryption calculation to the client so that balancing the workload and shortening the running time of the algorithm. The improved SSL protocol exchanges certificate identifier instead of certificate entities between client and server, which reduces the message payload. The improved SSL protocol improves the decryption speed and reduces the handshake communication load compared to the original SSL protocol.
Keywords: Mobile database, security transmission, improved SSL protocol, RSA encryption algorithm, identity authentication
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #64, pp. 581-586
Title of the Paper: Antenna Design for Switched-Beam Systems on Mobile Terminal
Authors: Monthippa Uthansakul, Peerapong Uthansakul
Abstract: In this paper, we propose a small switched-beam antenna for mobile terminal. This kind of antenna is a single compact slot antenna fed by microstrip line. This proposed antenna provides three different radiation patterns. The antenna is designed to cover 3G Universal Mobile Telecommunication Systems (UMTS; 1.92- 2.17 GHz). Its advantage is small of size and easy to manufacture. The performance of proposed antenna is confirmed by both simulation and experimental results. In addition, the antenna is also tested under real environment to see its real performance in terms of signal strength and throughput. The obtained results show that it provides higher signal strength and throughput over the use of omni-directional antenna as currently employed in mobile terminal.
Keywords: 3G phone, Antenna design, Array antennas, Microstrip antenna, Mobile phone antennas, Switched-beam antennas
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #63, pp. 572-580
Title of the Paper: Optical Wavelength and Dimensions Tolerance Criterion for Multimode Interference Couplers
Authors: Abdulaziz M. Al-Hetar, Zaid A. Shamsan
Abstract: The self-imaging property of a homogeneous multi-moded planar optical waveguide has been applied in the design optical couplers based on multimode Interference (MMI). Based on this design, the optical wavelength and dimensions tolerance for MMI-3dB couplers are investigated analytically. They are shown to be inversely proportional to the multimode section width. Among Symmetrical, paired, and general mechanism interference types, the symmetrical one has the highest optical wavelength and dimensions tolerance.
Keywords: MMI coupler, Power splitter, Bandwidth, Polarization, Self-image
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #62, pp. 567-571
Title of the Paper: Performance of Hybrid Virtual Force Algorithms on Mobile Deployment in Wireless Sensor Networks
Authors: Jyh-Horng Wen, Cheng-Chih Yang, Yung-Fa Huang
Abstract: In this paper, three Hybrid Virtual Force Algorithms (HVFA) are proposed to improve the performance of coverage rate, connectivity and energy-efficient moving for dynamic deployment in Wireless Sensor Networks (WSNs). Potential-field-based virtual force algorithm (PF-VFA) can improve the coverage area by distributed mobile deployment. However, the network connectivity performance is degraded due the unevenly node density in WSNs. Therefore, in this paper, a local-density based VFA (LD-VFA) is proposed to improve the network connectivity. Moreover, to further compromise the coverage rate and network connectivity, the sector-density based PF-VFA (PFSD-VFA) is proposed to provide the global density balance. The energy-efficiency of the energy consumption for mobile nodes is considered as one performance metric for sensor dynamic deployment in WSNs. Therefore, a performance combining coverage rate, connectivity, and total moving distance are investigated for the HVFA schemes. Simulation results show that the combing local-density and sector-density VFA (LDSD-VFA) outperform the other VFA schemes.
Keywords: Hybrid virtual force algorithms, coverage rate, network connectivity, local-node-density, sector-nodedensity, energy-efficiency
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #61, pp. 558-566
Title of the Paper: Performance Evaluation of MC-CDMA and DS-CDMA Schemes in Satellite Communications Based on VSAT Networks
Authors: Mohammed El Jourmi, Hassan El Ghazi, Abdellatif Bennis, Hassan Ouahmane
Abstract: The purpose of this paper is to model and evaluate the performance of a satellite communication system based on VSAT networks. In this study, the envisaged system adopts the Direct Sequence Code Division Multiple Access (DS-CDMA) scheme and Multi-Carrier Code Division Multiple Access (MC-CDMA). To improve the performance of the modeled system, and get a low bit error rate, we proposed the use of Forward Error Correction (FEC). In this paper, the performances of the satellite communication system based on VSAT network have been examined over AWGN channel. The simulation results are obtained for uncoded and coded system in the uplink case. The performance of the system is given in terms of Bit Error Rate (BER). The results analysis shows that the coded system performance is better compared to uncoded system performance. Under AWGN channel, particularly in uplink case, the DS-CDMA scheme works better than MC-CDMA in the satellite applications based on VSAT networks.
Keywords: VSAT Network, MC-CDMA, DS-CDMA, Convolutional Code, Uplink, Ku band
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #60, pp. 548-557
Title of the Paper: An Efficient Spectrum Allocation Mechanism for Cognitive Radio Networks
Authors: Fatima Zohra Benidris, Badr Benmammar, Fethi Tarik Bendimerad
Abstract: Cognitive Radio (CR) is viewed as a novel approach for improving the utilization of a precious natural resource: the radio electromagnetic spectrum. CRs can efficiently share the available spectrum both in licensed and unlicensed bands with the neighboring devices. The efficient use of available spectrum is becoming more and more critical with increasing demand and usage of the radio spectrum. To this extend, in this paper we propose an approach to solve the spectrum allocation/sharing problem using cooperation spectrum management method based on coalition that enables CR devices to share the unutilized spectrum efficiently. The key aspect of our design is the deployment of Multi-Agent System (MAS) where agents are deployed on each device and are grouped into coalitions. The powerful node in each coalition is selected to be a leader which handles allocation requests received from CRs of the same coalition. All these coalitions cooperate in order to have a better use of the spectrum. Our simulation results show that the proposed solution provide an intelligent management and achieves good performance in terms of spectrum access/sharing, within the span of few message.
Keywords: Cognitive Radio, Multi-Agent Systems, Cooperation, Spectrum allocation/sharing, Coalition; Artificial intelligence
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #59, pp. 534-547
Title of the Paper: A Backbone Formation Algorithm in Wireless Sensor Network Based on Pursuit Algorithm
Authors: Yisong Jiang, Weiren Shi
Abstract: In wireless sensor network, virtual backbone formulation is a cost effective method to complete the broadcasting. Minimum connected dominating set is an outstanding candidate of virtual backbone. However, it is NP-Hard to find a minimum connected dominating set in an arbitrary graph. In this paper, we propose a novel backbone formation algorithm to construct a connected dominating set. In the proposed method, a dominating set and action sets are got at first. Then, sink executes the pursuit algorithm, in which nodes are treated as learning automata and action probability vector is changed with time, and chooses actions from their action sets to construct a connected dominated set Finally, the automaton converges to a common policy and an approximate solution of the minimum connected dominating set is got. It is also shown that our method is ε-optimality with the changing speed of learning parameter. The simulation results show that our algorithm has a good performance in terms on the size of backbone, the message overhead and average node degree.
Keywords: Backbone, Wireless sensor network, connected dominating set, pursuit algorithm
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #58, pp. 523-533
Title of the Paper: On the Design of Compact Dual Mode Multi-Band Bandpass Filters Using Triangular, Circular and Hexagonal Shape Open – Loop Resonators
Authors: Raj Kumar, Nagendra Kushwaha, Rvs Ram Krishna
Abstract: The design and performance of a band pass filter for UWB communications is presented in this paper. Open loop resonators consisting of parallel arms (stubs) protruding from a 50Ω transmission line create the required rejection bands. The arms height, width and spacing control the bandwidth achieved by the filter. Each pair of arm creates one reject band in the transmission response. Three filters; one with hexagonal shape arms, another with circular shape arms and still another with triangular shape arms are proposed. The triangular shape offers wider pass band along with a narrow stop band response whereas the hexagonal shape exhibits wider stop band and a narrow band pass response. The achieved pass band (experimentally measured) for the filter with triangular arm resonator is from DC to 3.585 GHz, 5.12 GHz to 6.65 GHz and from 7.81 GHz to 8.86 GHz. The corresponding stop bands are from 3.585 - 5.12 GHz, 6.65-7.81 GHz and 8.86 – 10.0 GHz. The filters are expected to be useful in communication devices operating in the UWB frequency range.
Keywords: Microstrip line, Filters, Multi-band filter, Open Loop Resonators, Communication System
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #57, pp. 513-522
Title of the Paper: New Routing Methodology Focusing on the Hierarchical Structure of Control Time Scale
Authors: Yudai Honma, Masaki Aida, Hideyuki Shimonishi
Abstract: We present a new routing methodology that focuses on the hierarchical structure of a control time scale. The key concept of this study is to simultaneously implement both multiple routing protocols: OSPF routing (shortest-path) and MLB routing (multi-path). By considering the difference in their control time scales, we construct a new routing scheme that deals with sudden changes in network conditions. That is, we design an architecture that basically allocates packets to the shortest path route and simultaneously allocates packets to an alternative route when congestion occurs. Furthermore, using simulations, we have also shown that this methodology achieves more efficient use of the network and significant improvements in end-to-end delays. We believe this methodology will pave the way for hierarchical approaches based on the control time-scale methodology.
Keywords: hierarchical routing, control time scale, OSPF, MLB routing
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #56, pp. 505-512
Title of the Paper: Adaptive Modulation for DFE Equalized Systems
Authors: Mohamed Lassaad Ammari, Francois Gagnon
Abstract: In this paper, an adaptive quadrature amplitude modulation (AQAM) scheme for an equalized system over a selective channel is investigated. To reduce intersymbol interference (ISI), a minimum-mean-squared- error decision feedback equalizer (MMSE-DFE) with an unbiased decision rule is used. In order to select the appropriate modulation mode, the receiver estimates the MSE at the equalizer output. This estimated MSE is then sent back to the transmitter which adjusts the modulation level. The influence of channel variations on the AQAM- DFE performances was also investigated. Simulation results illustrate that the MSE is accurately estimated and represents a viable switching metric. It is also shown that switching between different modulation modes does not affect the equalizer coefficients adaptation. Linear region of practical transmitter amplifiers is limited. Thus when switching from one modulation scheme to an other, it is important to control the peak power.
Keywords: Adaptive modulation, MMSE-DFE, unbiased receiver
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #55, pp. 497-504
Title of the Paper: Performance of Fibonacci-Binary Sequences for SLM Based OFDM Systems
Authors: Saheed Adegbite, Scott Mcmeekin, Brian Stewart
Abstract: Binary sequences such as chaotic-binary (CB) sequences derived from an iterative chaotic equation have been used in selected mapping (SLM) methods to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Though CB sequences have been shown to produce good PAPR reduction performance, their implementation requires a significant number of complex computations which may increase both design costs and energy requirements. This paper presents an alternative form of binary sequences derived from a Fibonacci series and referred to as Fibonacci-Binary (FB) sequences. Simulations show that although CB sequences produce slightly improved PAPR reduction performance over the proposed FB sequences for larger numbers of applied SLM vectors, both forms of binary sequences produce similar bit-error-rate (BER) performance even in the presence of non-linear power amplifier distortion. In terms of computational complexity however, it is shown that FB sequences have significantly reduced computational requirements over CB sequences and thus may be considered as preferred option for reducing PAPR in SLM based OFDM systems.
Keywords: Fibonacci series, Fibonacci-Binary, Chaotic-Binary, OFDM, PAPR reduction, Selected mapping
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #54, pp. 486-496
Title of the Paper: On the Statistics of the Channel Capacity for a DS/FFH-CDMA System
Authors: P. Varzakas
Abstract: In this paper, a constant total system’s allocated bandwidth hybrid direct-sequence/fast frequency hopping code-division multiple-access (DS/FFH-CDMA) cellular system, when operating in a Rayleigh fading environment, is examined. The described analysis leads to a novel-closed form expression for the probability density function (pdf) of the channel capacity per user, which relates the pdf of the channel capacity and all system’s parameters. In addition, the probability that the channel capacity per user does not exceed the available average channel capacity per user, in a Rayleigh fading environment, is derived. Finally, respective numerical results are presented to investigate the sensitivity of this probability value from various system’s parameters.
Keywords: Channel capacity, Hybrid DS/FFH-CDMA systems, Cellular systems, Rayleigh fading
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #53, pp. 480-485
Title of the Paper: Earthing Resistance Tester Developed Using Resonant Circuit Technology with No Auxiliary Electrodes
Authors: Kazuo Murakawa, Hitoshi Kijima
Abstract: This paper presents an earthing resistance tester that uses resonant circuit technology to operate with a simple earthing electrode and without auxiliary electrodes. The measurement mechanism is analyzed using an earth return circuit model. The earthing electrode being tested, a lead wire, a return wire and the soil itself comprise the earth return circuit (LRC serial circuit). The requirements for this measurement method are obtained from numerical simulations, taking the lengths of the lead wire and the return wire to be 1 m and 20 m, and soil resistivity less than 10-2 s/m. The developed tester can measure the earthing resistance by evaluating the loop impedance of the earth return circuit at its resonant frequency, using a resonant frequency in the range of 100 kHz to 1.5 MHz. The return wire need only be placed on the soil surface without any termination. Earthing resistance measurements made by the developed tester and a conventional tester (3-pole method) differed by less than ±20% for earthing resistance values between 50 Ω and 400 Ω. The developed tester is a good way to test a simple earth electrode with an earthing resistance value of around 100 Ω.
Keywords: Earthing Resistance, An Earth Return Circuit Model, Tester, Without Auxiliary Electrodes, Resonant Frequency, Experiments And Examinations
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #52, pp. 470-479
Title of the Paper: Multilayer Perceptron Equalizer for Optical Communication Systems
Authors: Tiago F. B. de Sousa, Marcelo A. C. Fernandes
Abstract: Optical fibers are now widely used in communication systems, mainly because they offer faster data transmission speeds. Despite this great advantage, problems remain that prevent the full exploitation of optical connection: by increasing transmission rates over longer distances, the data is affected by nonlinear inter-symbol interference caused by dispersion phenomena. Adaptive equalizers can be used to compensate for the effects caused by nonlinear channel responses, restoring the signal originally transmitted. The present work proposes a multilayer perceptron equalizer based on artificial neural networks. The technique was validated using a simulated optical channel, and was compared with other adaptive equalization techniques.
Keywords: Nonlinear Optical Signal Processing, Dispersion Compensation Devices, Fiber Optics Communications, Neural Networks
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #51, pp. 462-469
Title of the Paper: Normalized Power Spectrum Analysis Based on Linea Prediction Code (LPC) Using Time Integral Procedures
Authors: Kazuo Murakawa, Hidenori Ito, Masao Masugi, Hitoshi Kijima
Abstract: Recently malfunctions of telecommunication installations caused by switching noises of electric equipment or devices have been increasing. The switching noises usually have low frequency components less than 50Hz and also more than 9kHz or 150 kHz. It is useful to detect power spectrum of noises in order to solve EMC problems. The LPC (Linear Prediction Code) method is known as a powerful frequency estimation method. This paper proposes a new normalized power spectrum analysis technique based on LPC. Introducing time integration on a time series of the noise waves to the LPC shows that noise power spectrum (frequencies and levels) can be estimated more precisely than using the conventional LPC method. Estimated deviations of frequency and NPS (normalized power spectrum) between given frequencies and extracted frequencies of quasi signals are less than 4%, and the proposed technique can also extract low frequencies with short durations from time series of noises.
Keywords: LPC (Linear prediction code), frequency analysis, time integral, simulations and experiments
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #50, pp. 452-461
Title of the Paper: Recognition and Modelling of Bursty Period of Flow
Authors: Lucia Figuli, Juraj Smiesko
Abstract: This article presents some methods for recognition and modelling of bursty period of event flow. The flow of events represents generally 0/1 bit sequences. We used the Markov modulated Regular process (MMRP) and Bernoulli process (MMBP) for the description of flows with bursty period. We derived probability distribution of spaces of MMRP processes and used it for estimation of unknown parameters of process. Because the uncomfortableness of flows with MMP processes, we used a Effective bandwidth, to gain parameters of MMBP and obtain a process which will over design considered flow.
Keywords: Burst period, Markov modulated process MMP, Bernoulli process, IPTV traffic, Bit sequences, Effective Bandwidth, LATEX
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #49, pp. 444-451
Title of the Paper: Three Way Authentication Protocol for Privacy Preserving and Ownership Authentication Transfer for Ubiquitous Computing Devices
Authors: Pradeep B. H., Sanjay Singh
Abstract: Now a days almost everybody is having a portable communication device, be it a laptop, a tablet or smart phones. The user would like to have all the services at his fingertips and access them through the portable device he owns. The user would exchange data with the other user or the service provider or control the smart appliances at his home. The interactions between the user’s device and the service provider must be secure enough regardless of the type of device used to access or utilize the services. In this paper we propose a ”Three Way Authentication (TWA)” technique intended to preserve the user privacy and to accomplish ownership authentication in order to securely deliver the services to the user devices. This technique will also help the users or the service providers to check whether the device is compromised or not with the help of the encrypted pass-phrases that are being exchanged. The users use the devices to store most of the valuable information and will prove risky when the device is borrowed by the other user or when it is lost or stolen. To safeguard the user data and also to preserve user privacy we also propose the technique of Authenticated Ownership Transfer (AOT). The user who sells the device has to transfer the ownership of the device under sale. Once the ownership has been transferred, the old owner will not be able to use that device at any cost. Neither of the users will be able to use the device if the process of ownership has not been carried out properly. This also takes care of the scenario when the device has been stolen or lost, avoiding the impersonation attack. The proposed protocol has been modeled and tested with Automated Validation of Internet Security Protocols and Applications (AVISPA) and is found to be safe.
Keywords: Ubiquitous Computing, Three Way Authentication, Ownership Authentication Transfer
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #48, pp. 430-443
Title of the Paper: Performance Evaluation for the Cooperative Communication Systems in Decode-and-Forward Mode with a Maximal Ratio Combining Scheme
Authors: Jyh-Horng Wen, Chung-Hua Chiang, Yi-Shan Lin, Cheng-Ying Yang
Abstract: Cooperative system is a tendency in the future communications because it provides a spatial diversity to improve the system performance. Three strategies including Amplify-and-Forward (AF) mode, Decode-and-Forward (DF) mode and Compress and Forward (CF) mode could be candidate to be employed in the system. This work considers the cooperative communication systems in DF Mode. The scenario includes one source station, M relay stations and N destinations. For the whole system, the maximum throughput approaching is the major purpose in this work. Hence, to select the relay stations for signal transmission could be the important scheme to achieve the best system performance. Based on the exhaustive search method, easily to realize, the optimal selection scheme could be found with a highly complicated calculation. In order to reduce the computational complexity, a sub-optimal solution with a greedy algorithm applied for the relay selection scheme is proposed. With different situations of the communication systems, the performances evaluations obtained by both the proposed algorithm and the exhaustive search method are given for comparison. It shows the proposed algorithm could provide a solution approaches to the optimal one. It is better to apply the proposed scheme when the number of relay stations is much larger than that of destination stations.
Keywords: Cooperative communication, Relay selection, Decode-and-Forward (DF) mode, Exhaustive search, Greedy algorithm
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #47, pp. 424-429
Title of the Paper: Capacity Analysis of MIMO-OFDM Decode-and-Forward (DF) Relay Networkin the Presence of High Power Amplifiers Nonlinearity
Authors: Ishtiaq Ahmad, Khaled Ali Abuhasel
Abstract: This paper presents the ergodic capacity of nonlinear MIMO-OFDM Decode-and-Forward (DF) relay network.Nonlinearities in wireless communication channels can arise at the transmitter or the receiver side. In this work, we focus on the transmitter-side nonlinearities induced by the High Power Amplifier (HPA), the last stage in the communication chain at the base station (BS) and the relay stations (RS’s). We consider MIMO-OFDM relaying system where the BS, RS’s, and the mobile stations (MS’s) are all equipped with transmitting and receiving antennas, and HPAs at the BS and RS’s exhibit general nonlinear behaviors. We derive closed-form expression for the ergodic capacity of the DF relaying protocol. Our results show that high-order MIMO systems suffer more capacity loss due to HPA nonlinearity than low-order MIMO systems, and that more capacity loss is experienced in multihop relaying over nonlinear channels as more relay hops are involved.
Keywords: Amplifier nonlinearity, MIMO-OFDM, Ergodic Capacity, Decode-and-forward, Relay Network
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #46, pp. 417-423
Title of the Paper: Non-Blind Beamforming Generalized Receiver with DOA Estimation in MIMO Wireless Communication Systems
Authors: Jingui Liu, Vycheslav Tuzlukov
Abstract: We investigate the generalized receiver (GR) constructed based on the generalized approach to signal processing in noise employing non-blind beamforming algorithms and direction of arrival (DOA) estimation, which is implemented by multiple-input multiple-output (MIMO) wireless communication systems. We compare three non-blind beamforming algorithms, namely, the least mean square (LMS), the recursive least square (RLS), and the sample matrix inverse (SMI) algorithms under GR employment in MIMO wireless communication systems. DOA estimation techniques are applied based on multiple signal classification (MUSIC) and estimation of signal parameters via rotational invariance technique (ESPRIT). We suppose several GR structures employing the above mentioned non-blind beamforming algorithms jointly with DOA estimation procedure. Comparative analysis of simulation results allows us to conclude that the performance curves of GR with considered non-blind beamforming algorithms are very close to each other. Also, simulation results demonstrate superiority in the output signal-to-interference-plus-noise ratio (SINR) under employment of GR with the discussed non-blind beamforming algorithms and DOA estimation in MIMO wireless communication systems in comparison with the correlation receiver that is optimal in the Neyman-Pearson sense if a priori information about the information signal parameters is known.
Keywords: Generalized receiver, non-blind beamforming, direction of arrival (DOA), multiple signal classification (MUSIC), signal-to-interference-plus-noise ratio (SINR), root-mean-square error (RMSE)
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #45, pp. 402-416
Title of the Paper: Energy-Efficient and QoS-Ware Resource Allocation for Relay-Enhanced OFDMA Wireless Cellular Networks
Authors: Xiaoyan Huang, Supeng Leng, Fan Wu, Yuming Mao
Abstract: We focus on energy-efficient resource allocation with quality of service (QoS) guarantee for orthogonal frequency division multiple access (OFDMA) based wireless cellular networks with decode-andforward (DF) relaying. The joint transmission mode selection, subcarrier allocation and power control for the energy efficiency (EE) maximization problem is formulated as a non-convex and combinatorial optimization problem with the consideration of both the transmit and circuit power consumption, QoS requirements of mobile stations (MSs), as well as individual power constraints at base station (BS) and relay stations (RSs). To solve the global optimization problem, a low-complexity transmission mode selection and subcarrier allocation algorithm is performed firstly. By exploiting the properties of relaying transmission and nonlinear fractional programming, an iterative power control algorithm is devised to optimize the power allocation of BS and RSs subsequently. Numerical results demonstrate that the proposed algorithm achieves significant EE improvement compared with the conventional spectral-efficient design and the energy-efficient design without the assistance of relaying transmission.
Keywords: radio resource allocation, QoS, energy efficiency, relaying, subcarrier allocation, power control
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #44, pp. 394-401
Title of the Paper: Space Diversity Path Loss in a Modern Factory at Frequency of 2.4 GHz
Authors: Supachai Phaiboon
Abstract: This paper presents radio wave propagation characteristics of a modern factory at a frequency of 2.4 GHz. Fading deeps from space diversity at transmitting and receiving antennas are proposed with measured data. These models provide both large scale fading and boundary limitation in which almost measured data is contained. There are five path loss categories, namely LOS, NLOS same area, NLOS different area, LOS+NLOS same area and LOS+NLOS all areas. These categories provide different path loss characteristics in each environment. Comparisons between conventional models and purposed models are discussed and show that the purposed models provide prediction with in boundaries for all categories, especially for LOS model and the wall attenuation factor (WAF) model. It is also found that machine arrangements do not affect significantly the path loss characteristics.
Keywords: Space diversity, fading deep, 2.4 GHz path loss, modern factory, one slope model
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #43, pp. 386-393
Title of the Paper: A Feasible Power Saving Scheduling Approach in WiMAX 802.16e Networks
Authors: Wen-Chuan Huang
Abstract: IEEE 802.16 is a novel broadband wireless access standard. Quality of service (QoS) guarantee and power saving are two important factor in IEEE 802.16 standard. Unsolicited grant service (UGS) is a constant bit rate QoS service and is defined in IEEE 802.16 standard. Power saving classes of type II (PSCs-II) is provided in IEEE 802.16 standard for repeat fixed active and sleep frames. However, IEEE 802.16 standard does not define how to develop an approach for power saving. This paper aims to provide a solution that provides a power saving schedule for one mobile station with multi UGS connections. The proposed approach is named Bucket Checker (BC) that follows the IEEE 802.16 standard definitions, UGS and PSCs-II. In addition, BC aims to provide a best power saving efficiency. By the numerical results, it shows that the proposed approach has better power saving efficiency and always follows QoS requirements.
Keywords: WiMAX, 802.16, power saving, schedule, UGS, PSCs
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #42, pp. 378-385
Title of the Paper: A QoS Balancing Model for Mobile Ad hoc Networks
Authors: Heng Luo, David. I. Laurenson, Ai-Huang Guo, Jianping Chen, Peide Yang, Hua Jiang
Abstract: Quality of Service (QoS) provision is required for MANETs in recent years to support the rapid growth of video in mobile traffic. In spite of numerous QoS routing protocols, litter literature, it is observed, discusses about the QoS balancing model with several QoS metrics considered simultaneously, which is realistic in real applications, due to various units and attributes of QoS metrics. A new model, denoted by SAW-AHP, which is a combination of Simple Additive Weighting (SAW) and Analytic Hierarchical Process (AHP), is proposed in this paper to balance the competing QoS metrics. Despite of different units and attributes of diverse QoS metrics, SAW-AHP is able to rank the alternative routing protocols reliably and consistently by considering the relative preference of QoS metrics which is neglected by much literature.
Keywords: Mobile ad hoc network, Routing Protocol, QoS, SAW-AHP, Mobile traffic, Simulation
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #41, pp. 372-377
Title of the Paper: Robust Fading Channel Estimation under Parameter and Process Noise Uncertainty with Risk Sensitive Filter and Its Comparison with CRLB
Authors: K .Rajendra Prasad, M. Srinivasan, T. Satya Savithri
Abstract: As an alternative to Kalman filtering, a risk-sensitive filtering is proposed for a linear time-varying fading channel estimation problem and its robustness against the parameter and process noise uncertainty in the channel model is explored. The time-varying channel estimation problem is formulated as time varying Finite Impulse Response (FIR) filter with a known rectangular pulse at input and Gaussian noise corrupted signal at output. In time-varying FIR filter, estimation of time varying coefficients with uncertain condition is an important and critical task. In literature, Kalman filter (KF) based fading channel estimation approach has been studied and it has limitations that lead to inaccurate estimation when there is a high level of uncertainty in initial conditions and bias in system model and/or noise covariance. To overcome the above limitation, the risk sensitive filter (RSF) is proposed. In this work, bias in channel is considered to investigate the effect of risk/cost performance of channel estimation problems. The special feature of risk sensitive filter is it uses a risk factor/parameter in the exponential cost function, so that the probability density function of variable of interest to be estimated and to be reshaped with proper tuning of risk factor, thus robustness again uncertainty can be achieved. In this paper, with KF and RSF the robustness against uncertainty in channel model parameter and process noise covariance is presented. Numerical simulation result has been carried out and the Root Mean Square error (RMSE) with Monte Carlo runs is studied. In order to estimate the Channel parameter under uncertain conditions, the performance of risk sensitive filter is improved than the conventional Kalman filter. To investigate the theoretical performance, Cramer-Rao Lower Bound (CRLB) is applied and its channel estimation performance is compared with performance obtained by the filters. When uncertainty is present in parameter, the risk sensitive filter’s performance is comparatively close to that of CRLB performance than the performance of Kalman Filter.
Keywords: Channel Estimation, Fading Channel, Time-varying Coefficients, Kalman Filter, Risk Sensitive Filter, Cramer-Rao Lower Bound,Uncertainty
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #40, pp. 363-371
Title of the Paper: PAPR Reduction Scheme for MISO and MIMO OFDM Systems with Limited Feedback
Authors: Joonwoo Shin, Bangwon Seo
Abstract: For multiple-input single-output (MISO) and multiple-input multiple output (MIMO) beamforming (BF) orthogonal frequency division multiplexing (OFDM) systems employing cluster-based codebook index feedback (CCIF), a new peak-to-average power ratio (PAPR) reduction method is proposed. In the proposed method, a dummy signal is generated in null space of the channel and superimposed on the original signal to reduce the PAPR. First, we modify the conventional method to apply to the MISO/MIMO OFDM system with CCIF based BF. From the observation that the conventional method will severely degrade the bit error rate (BER) performance, weight functions for the dummy signal across the subcarriers are proposed. The proposed weight functions are found by both nonlinear optimal and simple suboptimal manners. Through simulation results, it is shown that the proposed scheme can make the BER loss be negligible at the expense of some loss in PAPR reduction gain.
Keywords: OFDM, MIMO, PAPR reduction, transmit beamforming, limited feedback
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #39, pp. 355-362
Title of the Paper: On the Impact of User Payload on Deployment Requirements of LTE Networks
Authors: A. Hameed, Ali Oudah
Abstract: Ever since its inception, Long Term Evolution (LTE) of Universal Mobile Telecommunications System (UMTS) standard has gained great deal of momentum from wireless operators as well as end users. This paper addresses the impact of user or traffic load in LTE cells on total harmful interference emitted towards a victim cell. This is done through deriving coexistence requirements, in terms of land separation, when deploying LTE base stations in band 2.6 GHz. In view of the developed model and results, the interference radiated from the aggressor to the victim is directly proportional with the aggressor’s traffic load. In other words, the higher the payload of the aggressor, the higher the interference received by the victim.
Keywords: LTE, traffic load, interference, coexistence, inter-cell interference, protection criterion
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #38, pp. 348-354
Title of the Paper: Radiation Characteristics of Circular Microstrip Patch Antenna with and without Air Gap Using Neuro-Spectral Computation Approach
Authors: Sami Bedra, Randa Bedra
Abstract: In this paper, we propose an artificial neural network (ANN) in conjunction with spectral domain formulation for fast and accurate determination of the resonant frequency and bandwidth of circular microstrip antenna with and without air gap. This neurospectral approach reduces the problem complexity. The results obtained from the neural model are in very good agreement with the experimental results available in the literature. Finally, numerical results for the air gap tuning effect on the resonant frequency and bandwidth of circular microstrip structure are also presented.
Keywords: Circular Microstrip Antenna, Artificial Neural Network, Spectral Analysis, Tunable Structure
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #37, pp. 340-347
Title of the Paper: Threshold Attribute Based Universal Designated Verifier Signature Scheme in the Standard Model
Authors: Feng Cai, Wangmei Guo, Ximeng Liu
Abstract: In universal designated verifier signature scheme, signature holder can designate the signature to any desired designated verifier. Only the designated verifier can believe that the signature holder does have a valid publicly verifiable signature. Attribute based encryption is a novel public key primitive in cryptography and attribute based signature can provide a powerful way for users to control their privacy. In this paper, we propose a threshold attribute based universal designated verifier signature scheme whose security can be proven in the standard model. The security of our scheme depends on the Bilinear Diffie-Hellman (BDH) assumption.
Keywords: Bilinear pairings, Attribute-based, Universal designated verifier signature, Provable secure
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #36, pp. 329-339
Title of the Paper: Performance Enhancement of VSAT MC-CDMA System Using Channel Coding Techniques and Predistortion over Rayleigh Channel
Authors: Mohammed El Jourmi, Hassan El Ghazi, Abdellatif Bennis, Hassan Ouahmane
Abstract: In this paper, the performance of VSAT network, in uplink (earth station to a geostationary satellite) and Ku-band have been examined over Rayleigh channel. The most popular type of multiple access schemes: Code Division Multiple Access (CDMA) combined with the multi-carrier transmission system OFDM is used in this study, in order to obtain a densification of data traffic on the network and achieve a high data rate. To improve the performance of the envisaged system, and get a very low bit error rate, we proposed the use of strategies allowing the correction of errors induced by the imperfections of the communication channel. Channel coding techniques used in this study are (LDPC codes, Turbo codes and convolutional codes). In the simulation results, we have demonstrated the effectiveness of each coding strategy in our communication system. The integration of LDPC coding in our transmission chain has provided a significant gain compared to other encoding schemes, and the bit error rate (BER) has reached a satisfying level at a low energy per bit to noise power spectral density ratio (Eb/No). To compensate the effect of the non-linearity of the High Power Amplifier HPA, a predistortion technique is adopted to further improve performance of the envisaged system.
Keywords: VSAT Network, MC-CDMA scheme, Channel coding, predistortion, Ku band, Uplink
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #35, pp. 318-328
Title of the Paper: A Novel Coaxial Continuous Transverse Stub Antenna Array for High Frequency Satellite Applications
Authors: Jothilakshmi P., Raju S.
Abstract: The need for antenna with multiband capability is miniaturization of design and improvement of bandwidth. Planar antennas suffer narrow bandwidth problem. This paper focuses on the implementation of multiband high gain antenna array for wireless satellite and aircraft applications with improved bandwidth. The proposed antenna structure consists of three pair of radial coaxial stubs in a zigzag manner. The stub pair consists of one large stub and another small one to radiate for multiple frequency bands. This cascaded structure offers high directivity and gain with minimum return loss. This proposed antenna structure covers the frequency range of 10 GHz to 26 GHz. The fabricated antenna of the proposed structure radiated for four frequency bands with minimum return loss. These frequencies are well suited to satellite, space craft and military applications.
Keywords: Coaxial antenna, Multiband, Omni directional radiation pattern, S-Parameter, Directivity and Gain
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #34, pp. 309-317
Title of the Paper: A Routing Protocol for Utilizing Code Resources in Tactical Ad Hoc Networks with a Single Transceiver
Authors: Chuanbao Du, Houde Quan, Peizhang Cui, Xiaoming Wang
Abstract: A tactical ad hoc network is usually divided into several subnets by Code Division Multiple Access with frequency hopping sequences. In practice, the number of subnets needed in common tactical task is much lower than the theoretical networking capacity, which causes serious code resource waste. To make full use of idle code resources, we present a single-transceiver multi-channel routing protocol based on MCRP, named virtual dual-channel routing protocol (VDCRP). To overcome the disadvantages of serious overhead and high end-to-end delay of MCRP caused by employing multi-channel broadcast mechanism in multi-channel network environment, this proposed protocol provides a single-channel split-phase broadcast mechanism (SCSP) and a new metric called virtual dual-channel metric (VDCM). SCSP consists of control channel and data channel, which divides time frame into negotiation phase and data phase. In negotiation phase, all nodes exchange routing packets on the control channel. In data phase, all communication node pairs transmit and receive data packets on the data channel. We design the metric VDCM by considering both inter-flow interference and channel switching cost. Our simulation results show that compared to MCRP, VDCRP has higher resource utilization efficiency and lower ETE delay in multi-channel environment.
Keywords: virtual dual-channel networking scheme, code division multiple access, broadcast mechanism, routing metric, split phase, network throughput, average end-to-end delay
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #33, pp. 298-308
Title of the Paper: PAPR Reduction in an OFDM System Using Recursive Clipping and Filtering Technique
Authors: Md. Anamul Islam, N. Ahmed, Nizam Uddin Ahamed, Matiur Rahman, S. A. Aljunid
Abstract: An Orthogonal Frequency Division Multiplexing (OFDM) scheme is expected as an efficient technique for next generation wireless communications. However, high Peak to Average Power Ration (PAPR) of OFDM system is the main drawback which degrades the transmitter power efficiency causes poor performance of the system. To reduce PAPR of OFDM signal, several works on clipping technique have been proposed. This paper is incorporated the improvement of the PAPR and Bit Error Rate (BER) performance using clipping method. It has been shown from the result that by employing the recursive clipping and filtering, 11.45 dB of PAPR of original OFDM signal is reduced down to 4.77 dB. Hence, BER is also increased significantly. This research is carried out through MATLAB simulation and gradually measured the effect of PAPR on BER under AWGN channel for 16QAM scheme with 256 points OFDM. Moreover, it is studied the effect of OFDM signal while passing through High Power Amplifier (HPA). Finally, the PAPR reduction technique such as recursive clipping and filtering (RCF) is implemented.
Keywords: AWGN, HPA, OFDM, PAPR, QAM, Recursive Clopping and Filtering (RCF)
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #32, pp. 291-297
Title of the Paper: Rotated Hybrid, Energy-Efficient and Distributed (R-HEED) Clustering Protocol in WSN
Authors: Wail Mardini, Muneer Bani Yassein, Yaser Khamayseh, Barraq A. Ghaleb
Abstract: Minimizing the energy consumption for data transmission is one of the most important design considerations in Wireless Sensor Networks (WSNs). The clustering approach is considered one of the most effective methods to prolong the network lifetime in WSNs. Hybrid, Energy-Efficient, and Distributed clustering approach (HEED) is considered one of the most energy-efficient clustering algorithms that uses intra-communication cost and residual energy to elect the Cluster Heads (CHs). In this paper, we aim at examining different inter-cluster routing protocols over HEED and evaluate their performance. Moreover, an enhanced version to HEED, namely Rotated HEED (RHEED), is proposed in this paper. The modified version conducts the setup phase according to certain rules and schedule, with HEED performs this step at the beginning of some rounds. At the beginning of every round the CHs wait a pre-defined period of time to receive a re-clustering message from the BS. If they do not receive the re-clustering message, they will continue rotating the cluster head within the same cluster. The simulation results show that the RHEED outperforms the HEED protocol by more than 20% in term of network lifetime and residual energy.
Keywords: Sensor Network, Clustering Protocols, HEED, Cluster Head, Energy Consumption, Distributed, Hybrid
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #31, pp. 275-290
Title of the Paper: Design of a Crawler for Online Social Networks Analysis
Authors: Chi-In Wong, Kin-Yeung Wong, Kuong-Wai Ng, Wei Fan, Kai-Hau Yeung
Abstract: The growths of online Social Networks in scale and amount of information are immense in recent years. The analyses of the structure of online social networks have thus drawn much research interests. Before the analyses, the information and the characteristics of the structure have to be obtained. However, the complexity of today’s web technologies imposes challenges for collecting the data. In this paper, we discuss the design and implementation of a crawler for online social networks, and propose countermeasures to the technical challenges when crawling the networks in practice. Then, the crawled data is visualized and analyzed in graphs.
Keywords: Social Networks, Network Analysis, Crawler, Software Design, Automated Agents, Network Visualization
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #30, pp. 263-274
Title of the Paper: Linear Multiuser Detectors Using Linear, Circular and Concentric Circular Antenna Arrays in CDMA Communication Systems
Authors: Rekha Agarwal, Pinki Nayak
Abstract: The suitable use of an antenna array at the base station of a communication system results in improved Signal to Interference Ratio (SIR). In this paper, Linear Array (LA), Circular Array (CA) and Concentric Circular Antenna Array (CCAA) are used at the base station of a direct sequence code division multiple access (CDMA) systems. To suppress multiple access interference (MAI), the proposed scheme utilizes the spatial distribution of users as well as the time domain processing. The results show the significant improvement in capacity of CDMA system employing joint use of antenna array and multiuser detectors.
Keywords: Code Division Multiple Access, Bit error rate, Signal to Noise ratio, Multiuser detector, Antenna array
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #29, pp. 256-262
Title of the Paper: Level Crossing Rate of L-Branch SC Receiver over α-k-μ Fading Channel in the Presence α-k-μ Co-Channel Interference
Authors: Srdjan Jovkovic, Dejan Milic, Danijel Djosic, Milena Petrovic, Stanislav Veljkovic, Caslav Stefanovic
Abstract: Wireless communication system operating over interference limited, α-k-μ multipath fading channel is considered. Closed form expressions for cumulative distribution function and level crossing rate of the ratio of two k-μ random variables and the ratio of the two α-k-μ random variables are calculated. These expressions are used for evaluation level crossing rate of wireless communication system with L-branches, SIR based SC receiver operating over. α-k-μ multipath fading environment in the presence of co-channel interference affected to α-k-μ multipath fading. Numerical results are plotted to show Rice factor affects and α-k-μ fading severity parameter affects on level crossing rate.
Keywords: Average fade duration, α-k-μ distribution, co-channel interference, level crossing rate
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #28, pp. 249-255
Title of the Paper: A Scheme to Counter SSDF Attacks Based on Hard Decision in Cognitive Radio Networks
Authors: Jianqi Lu, Ping Wei
Abstract: Cognitive radio is a promising technology to improve the utilization of wireless spectrum resources. A serious threat to cognitive radio networks (CRN) which sense the spectrum in a cooperative manner is the transmission of false spectrum sensing data by malicious secondary nodes, namely spectrum sensing data falsification (SSDF) attacks. SSDF attackers start to attack the network in the case of independent attacks or cooperative attacks and impair the process of data fusion, the performance is deteriorated. In this paper, we propose a scheme that can mitigate the effect of SSDF attacks and improve the robustness of cooperative spectrum sensing (CSS) based on hard decision regardless of independent attacks or cooperative attacks. Simulations verify the effectiveness of the proposed scheme.
Keywords: Cognitive radio, Cooperative spectrum sensing, Spectrum sensing data falsification, Hard decision, Robustness
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #27, pp. 242-248
Title of the Paper: Design and Development of Quad-Band H-Shaped Microstrip Patch Antenna for WiFi and LTE Applications
Authors: P. Jothilakshmi, R. K. Vigneshwaran, R. Narasimman, B. Praveen
Abstract: The increasing demand in portable devices with wireless connectivity provides a challenge to design a RF front antenna. Microstrip patch antennas are widely used because they are of light weight, compact, easy to integrate. However the serious problem of patch antenna is their narrow band due to surface losses and large size of patch for better performance. So for the antenna miniaturization and bandwidth improvement H-shaped microstrip patch antenna was used. In this paper proposed a design of small sized, low profile patch antenna for wireless applications. The antenna multiband capability could be achieved by introducing a slot in the rectangular patch portion of h shaped patch antenna. The proposed antenna structure operates at four frequency bands of 2.2 GHz, 2.4 GHz, 2.8 GHz, and 2.9 GHz for WiFi and LTE applications. The performance measures of antenna return loss, voltage standing wave ratio, radiation pattern, gain, directivity and power were measured and tabulated, which shows that the antenna performance was good and results obtained were optimum. The simulation tool used for this design was Advanced Design System (ADS).
Keywords: Microstrip patch, Multiband Antenna, Gain, Return loss, Directivity, Radiation pattern
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #26, pp. 234-241
Title of the Paper: Design of GaN Based Optical Modulator with Mach-Zehnder Interferometer Structure
Authors: R. W. Purnamaningsih, N. R. Poespawati, I. Saraswati, E. Dogheche
Abstract: In this work we have designed a Mach Zehnder interferometer (MZI) for electro optic modulator at telecommunication wavelength using GaN on Sapphire. The knowledge of GaN sample optical properties were also investigated, resulting refractive index for the GaN layers were found to be nTE=2.279±0.001 and nTM = 2.316±0.001 and good temperatur stability. Optimization of the structure parameters and electrodes required for this structure was conducted accurately by theoretical tools using BPM methods. The results showed possibility to realize GaN based MZI for future optical modulator devices.
Keywords: GaN, Mach Zehnder interferometer, electro-optic, modulator
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #25, pp. 229-233
Title of the Paper: Adaptive Wireless Networks QoS Evaluation Analysis Through Enhanced Parameters Tuning Algorithms
Authors: Ben-Bin Chen, Hua-Ching Chen, Dong-Hui Guo
Abstract: The enhanced parameters tuning (EPT) algorithm is applied to adjust the parameters of 802.11e, i.e. arbitration inter frame space (AIFS), Contention window minimum (CWmin) and Contention window maximum (CWmax). The EPT tuning algorithm is proposed with the simple and effective adjustment in the priority combinations strategy to achieve the high quality of service (QoS). The internal competition of business analysis methods are determined to detect the channel busy probability. The EPT tunes the conflict probability by the variant setting of AIFS, CWmin and CWmax to approach the performance analysis while the traffic business is retreating into the idle and zero state. Three simulations results in the four businesses of wireless networks applications are applied to present the better adapt parameters regulation machines.
Keywords: Wireless Network, 802.11e, EDCA, EPT, QoS, Access Categories
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #24, pp. 217-228
Title of the Paper: Bit Error Probability and Capacity Analysis of Space-Time Block Codes in Spatially Correlated MIMO Weibull Fading Channels
Authors: Sudakar Singh Chauhan, Sanjay Kumar
Abstract: In this paper we examine the effects of spatial fading correlation on bit-error probability (BEP) and channel capacity of orthogonal space–time block codes (STBCs) over multiple-input multiple-output (MIMO) Weibull fading channel. We derive the characteristic function (cf) of the signal-to-noise ratio (SNR) which is linear combination of Laplace transforms weighted by the eigenvalues of the channel correlation matrix, with each component corresponds to an underlying Gamma probability density function (pdf). By efficient use of this method the close-form BEP and capacity expressions are derived for STBC with M-ary phase shift keying and M-ary quadrature amplitude modulation (M-PSK, M-QAM) over Weibull fading channels in the presence of spatial fading correlation.
Keywords: Space-Time Block Codes (STBC), bit error probability (BEP), channel capacity, correlated Weibull fading, Multiple-input multiple-output (MIMO)
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #23, pp. 209-216
Title of the Paper: Multipath Parameter Estimation and Channel Prediction for Wideband Mobile to Mobile Wireless Channel
Authors: Ramoni Adeogun
Abstract: In this paper, we investigate the estimation of multipath parameters and prediction of wideband multipath fading channels for mobile-to-mobile wireless communications. Based on a statistical model for mobile to mobile urban and suburban channels, we derive a parametrized model and utilize two-dimensional ESPRIT algorithm to jointly estimate the delay of arrival (DOA) and effective Doppler frequencies of the dominant paths from noisy channel observations. The parameter estimates are then used in the model to predict future states of the time-varying and frequency selective mobile-to-mobile channel. Simulations were performed to evaluate the performance of the prediction scheme and results show the potential for long range prediction in doubly selective mobile to mobile channels.
Keywords: Multipath fading channels, wideband mobile-to-mobile channel, parameter estimation, ESPRIT, channel prediction
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #22, pp.201-208
Title of the Paper: Spectral Efficiency Comparison of TDMA and DS-CDMA in Cellular Mobile Radio Systems
Authors: P. Varzakas
Abstract: A comparison of spectral efficiency achieved by time-division multiple-access (TDMA) and directsequence code-division multiple-access (DS-CDMA) systems, during cellular operation in a Rayleigh fading environment, is presented in this paper. Spectral efficiency, is evaluated in terms of the theoretically assigned downlink channel capacity per user (in the Shannon sense). In particular, in Rayleigh fading, channel capacity is estimated in an average sense considering the inherently offered diversity potential as a physical means for fading mitigation. In addition, both systems are assumed to allocate a fixed number of simultaneously transmitting users so that the total capacity of each system to be equally shared among its users. Hence, it is analytically shown that, under normalised conditions, the spectral efficiency of DS-CDMA is higher than that of TDMA regardless the fact that, in contrast to cellular TDMA, in cellular operation of DS-CDMA spectral efficiency is limited by multiple-access interference (MAI).
Keywords: Spectral efficiency, TDMA, DS-CDMA, Rayleigh fading
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #21, pp.195-200
Title of the Paper: Average Delay and Queue Length Model for WRRPQ
Authors: Tomáš Balogh, Martin Medvecký
Abstract: We present a new iterative mathematical model for calculating the average bandwidth assigned to traffic flows using a Weighted Round Robin with Priority queuing (WRRPQ) scheduler with both strict and rate controlled priority in IP based NGN networks. The bandwidth assignment estimation is based on the average packet length, link speed and the arrival rate. We prove the model outcome with examples and simulation results using NS2 simulator.
Keywords: Bandwidth Constraint Model, IP, NGN, WRRPQ, PQ, WRR
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #20, pp.186-194
Title of the Paper: Design and Implementation of Reconfigurable Microstrip Patch Antenna for S-Band Applications
Authors: P. Jothilakshmi, S. Shangaralavakusaraja
Abstract: Microstrip patch antennas have become one of the hotspot for researchers because of its various advantages and compatibility. Reconfigurable antennas have recently received much attention in wireless and satellite communication systems due to their selectivity for operating frequency and polarization. The active tuning of such antenna parameters is typically achieved by varying the switch conditions. A single prototype can be used to support multiple functions at multiple frequency bands. Objective is to design a reconfigurable antenna which operates at four different frequencies in S-band. The simulated antenna radiates at four different frequencies of 3.594 GHz, 3.7 GHz, 3.8 GHz, and 3.9 GHz and has a return loss of -29.47 dB, -15.44 dB, -30.38 dB, and -23.015 dB respectively. And then it is fabricated using FR4 as substrate and then it is found to be in good match with the simulated results.
Keywords: Reconfigurable, Fractal, Switches, Resonant frequency, Microstrip
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #19, pp.178-185
Title of the Paper: Blind Equalization Based on Direction Gradient Algorithm under Impulse Noise Environment
Authors: Xiao Ying, Yin Fuliang
Abstract: A new constant modulus blind equalization based on direction gradient algorithm was proposed, which can obtain robust convergence performance under impulse noise environment. The impulse noise has no more than two order moments, so constant modulus algorithm (CMA) based on stochastic gradient descent algorithm is often ill-convergence or divergence. The direction gradient algorithm uses the reliability of the output of the blind equalizer to determine the equalizer weights updating strategy, and the reliable region called decision circle is set according to the scatterplot of the send signal. If the output signal drops in the decision circle, the equalizer weights update according to the traditional CMA, otherwise it only keeps the sign of the output error, and the previous step instantaneous gradient is used to update the equalizer weights. The direction gradient algorithm can suppress the impulse noise interference effectively, which shows robust convergence performance under the impulse noise environment. Simulation results show that, compared with the fractional lower order CMA and the nonlinear transform CMA, the blind equalization based on direction gradient algorithm has the fastest convergence rate and the lowest steady state error.
Keywords: Blind equalization, direction gradient algorithm, impulse noise, constant modulus algorithm, decision circle
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #18, pp.171-177
Title of the Paper: Channel Capacity of Dual-Branch Maximal Ratio Combining under Worst Case of Fading Scenario
Authors: Mohammad Irfanul Hasan, Sanjay Kumar
Abstract: The worst case fading scenario can be represented by Nakagami-0.5 distribution, which is a special case of Nakagami- fading distribution. Under Nakagami-0.5 fading distribution closed-form expressions have been derived for the average channel capacity using uncorrelated dual-branch maximal ratio combining (MRC). This channel capacity is evaluated under Optimum Power with Rate Adaptation (OPRA) and Truncated Channel Inversion with Fixed Rate transmission (TIFR) schemes. And Numerical results of the average channel capacity under OPRA and TIFR have been presented and compared. It has been observed that OPRA provides higher capacity than TIFR under worst case of fading.
Keywords: Dual-Branch, channel capacity, maximal ratio combining, Nakagami- fading channels, truncated channel inversion with fixed rate, optimum power with rate adaptation
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #17, pp.162-170
Title of the Paper: Centralized Dynamic Spectrum Access in Cognitive Radio Networks Based on Cooperative and Non-Cooperative Game
Authors: Badr Benmammar, Belahcene Benyahia, Mahmoud Benhamida, Francine Krief
Abstract: Cognitive radio (CR) can be presented as a new paradigm coming from the bad use of spectrum resources, the problem of static spectrum allocation produce disequilibrium. The CR proposes opportunist radio spectrum exploitation. In this paper, we propose a centralized dynamic spectrum access in cognitive radio networks based on a powerful mathematical tool, the game theory on one side, and on multi-agent system on the other side. The problem of dynamic spectrum access (DSA) is modeled as a cooperative and non-cooperative spectrum access game where secondary users (SUs) access simultaneously multiple spectrum bands left available by primary users (PUs). Cooperation is modeled between PUs where non-cooperation is considered between SUs.
Keywords: Cognitive radio, dynamic spectrum access, cooperative game, non-cooperative game, multi-agent system
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #16, pp.148-161
Title of the Paper: Optimization of a Wide-Band 2-Shaped Patch Antenna for Wireless Communications
Authors: Ali El Alami, Saad Dosse Bennani, Moulhime El Bekkali, Ali Benbassou
Abstract: A design of a novel single-patch wide-band microstrip antenna: the 2-shaped patch antenna for wireless communications is proposed. Two opposite parallel slots are incorporated into the patch of a microstrip antenna to expand it bandwidth. The slot length, width and height of substrate are optimized to achieve a wide bandwidth. Finally, a 2-shaped patch antenna, resonating at frequencies of 2.4 GHz, 2.65 GHz and 2.90 GHz and having a bandwidth of 26.84%, is designed and simulated by software HFSS (High Frequency Structure Simulation).
Keywords: 2-shaped, patch antenna, parallel slots, wide-band, bandwidth, wireless communication, software HFSS
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #15, pp.143-147
Title of the Paper: Novel Approach of Designing Spreading Code using Genetic Algorithm
Authors: Arnab Shashi Hazari, Simita Kundu, Abhijit Chandra
Abstract: Modern communication systems extensively use Code Division Multiple Access (CDMA) technology that associates one unique code to each user. Therefore the generation of these spreading codes has drawn considerable attention amongst the researchers with a fundamental requirement of having as much distinct members as possible along with a constraint of minimizing the inter-code correlation. Since the operation of trade-off between the number of unique codes and peak cross-correlation value is nothing but a task of optimization; one such intelligent technique called Genetic Algorithm (GA) has been employed in this paper for the design of spreading codes. This has proved the uniqueness of our code generation algorithm over existing ones as it provides flexibility in selecting the number of orthogonal code pairs even when the code-length is constant. Interdependence between the characteristics of the designed code and the parameters of genetic optimization has been revealed by means of a number of design examples. Inherent properties of the GA-optimized spreading code have been analyzed from a number of perspectives. Finally, the worth of the proposed code in current wireless system has been substantiated by comparing its performance with other state-of-the-art spreading codes.
Keywords: Code Division Multiple Access (CDMA), Genetic Algorithm (GA), Kasami sequence, Orthogonal Gold code, Semi-Orthogonal Modified Large Set Kasami (SOMLK) sequence, Small Set Orthogonal Kasami (SSOK) code, Walsh code
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #14, pp.130-142
Title of the Paper: Error Probability Performance of Quadriphase DS-CDMA Wireless Communication Systems Based on Generalized Approach to Signal Processing
Authors: Vyacheslav Tuzlukov
Abstract: Probability of bit-error Per performance of asynchronous direct-sequence code-division multiple-access (DS-CDMA) wireless communication systems employing the generalized detector (GD) constructed based on the generalized approach to signal processing in noise is analyzed. The effects of pulse shaping, quadriphase or direct sequence quadriphase shift keying (DS-QPSK) spreading, aperiodic spreading sequences are considered in DS-CDMA based on GD and compared with the coherent Neyman-Pearson receiver. An exact probability of error Per expression and several approximations, namely, one using the characteristic function method, a simplified expression for the improved Gaussian approximation (IGA) and the simplified improved Gaussian approximation are derived. Under conditions typically satisfied in practice and even with a small number of interferers, the standard Gaussian approximation (SGA) for the multiple-access interference component of the GD test statistic and the probability of error Per performance is shown to be accurate. Moreover, the IGA is shown to reduce to the SGA for pulses with zero excess bandwidth. Second, the GD probability of error Per performance of quadriphase DS-CDMA is shown to be superior to that of bi-phase DS-CDMA. Numerical examples by Monte Carlo simulation are presented to illustrate the GD probability of error Per performance for square-root raisedcosine pulses and spreading factors of moderate to large values. Superiority of GD employment in CDMA sysems over the Neyman-Pearson receiver is demonstrated.
Keywords: Generalized detector, additive white Gaussian noise (AWGN), probability of bit-error, pulse shaping, generalized approach to signal processing (GASP), code division multiple-access, direct-sequence quadriphase shift-keying spreading
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #13, pp.116-129
Title of the Paper: An Efficient Layered FFT Approach for Reduction of PAPR, Spectral Re-growth and CFO on the Performance of an OFDM System
Authors: T. Deepa, R. Kumar
Abstract: Orthogonal frequency division multiplexing (OFDM) is an attractive multi carrier modulation technique for future broadband wireless transmission systems. However, the OFDM system exhibits high peak to average power ratio (PAPR) , large computational complexity by applying discrete Fourier transform (DFT) at the transmitter and inverse DFT (IDFT) at the receiver and sensitivity to carrier frequency offset (CFO), caused by Doppler shift which the carrier frequency difference between the transmitter and receiver. In this paper, we propose a divide & conquer FFT algorithm of an OFDM system to reduce PAPR and also analyze the impact of spectral re-growth and CFO on the performance of an OFDM system with and without D&C FFT approach. Simulation results show that OFDM system based D&C approach can achieve a good balance between complexity and system performance.
Keywords: CCDF, CFO, Divide & Conquer Approach, OFDM, PAPR, Spectral Re-growth
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #12, pp.109-115
Title of the Paper: Null Steering and Multi-Beams Design by Complex Weight of Antennas Array with the Use of APSO-GA
Authors: Hichem Chaker
Abstract: An efficient method based on the hybrid model with breeding and subpopulations, between genetic algorithm and a modified particle swarm optimizer for the linear antenna arrays pattern synthesis with prescribed nulls in the interference direction and multi-lobe beam forming by the complex weights of each array element is presented. In general, the pattern synthesis technique that generates a desired pattern is a greatly nonlinear optimization problem. The proposed method is based on the hybrid model algorithm and the linear antenna array synthesis was modeled as a multi-objective optimization problem. Multi-objective optimization is concerned with the maximization of a vector of objectives functions in the directions of desired signal that can be subject of a number of constraints. Several numerical results with the imposed single, multiple and broad nulls sectors are provided and compared with published results to illustrate the performance of the proposed method.
Keywords: Hybrid model, antenna array, interference suppression, multi-lobe beam forming
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #11, pp.99-108
Title of the Paper: Modelling, Design and Parametric Considerations for Different Dielectric Materials on Substrate Integrated Waveguide
Authors: Yasser Arfat, Sharad P. Singh, Sandeep Arya, Saleem Khan
Abstract: In this paper, the model of substrate integrated waveguide (SIW) has been analyzed and designed to investigate the effect of dielectric materials on its operating parameters. Parameters that have been evaluated in this work are electric field, return losses and the transmission gain. Printed circuit board (PCB), silicon (Si), Mica and polymethyl methacrylate (PMMA) are used as different dielectrics to evaluate the results in the frequency domain of 1 to 10 GHz. Design steps in an orderly manner were pursued for the optimization of geometrical dimensions followed by the finite-element method (FEM) based modeling of the SIW structure. The results obtained had shown that the maximum change in the electric field is observed for PMMA while the transmission gain increases with the increase in frequency upto 9.75 GHz and correspondingly the return loss is minimum at this frequency.
Keywords: Substrate integrated waveguide, finite element method, return loss, dielectric filled waveguide, transmission gain, electric field
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #10, pp.94-98
Title of the Paper: DGS Based Legendre Low-Pass Filters for RF/Microwave
Authors: Ashwani Kumar, A. K. Verma, Nainu P. Chaudhari
Abstract: The Legendre group of lowpass filters are designed and compared against several known types of filters at = 2.5GHz in lumped elements, microstrip and DGS environment. In microstrip format the Legendre Polynomial Product (LPP)-312 and 213 filters have reduced group delay variation in the passband, sharper cut-off and wider impedance matching BW. In the DGS format the measured selectivity of Legendre, LPP-312 and LPP-213 lowpass filters are 28.3dB/GHz, 18.8B/GHz and 18.2B/GHz. Their 20dB rejection BW (RBW) are 6.0 GHz, 7.7GHz and 7.9 GHz; it covers 20dB rejection up to 4fc-5fc in the stopband. The LPP-213 has better than 15dB impedance matching BW (94%) and more than 20dB rejection BW (7.3GHz).
Keywords: Group delay (GD), Defected Ground Structure (DGS), Low pass Filter (LPF), Legendre LPF
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #9, pp.80-93
Title of the Paper: Cross Layer Intrusion Detection System of Mobile Ad Hoc Networks Using Feature Selection Approach
Authors: T. Poongothai, K. Duraiswamy
Abstract: Existing intrusion detection system of Mobile ad hoc networks (MANET) examines all the features of network audit data. Some of the features of collected data may be redundant or irrelevant to the detection process. So it is vital to select the important features to increase the detection accuracy. This paper focuses on implementing two feature selection methods namely, Rough Set Theory (RST) and genetic algorithm (GA) combined with Support Vector Machines (SVM). Also the proposed system uses cross layer features instead of single layer features to maximize the performance. The results are validated through ns-2 simulations. The efficiency of the IDS is analyzed with varying network conditions by simulating routing attacks. The system has achieved an overall detection accuracy of detection with all features is 96.37, rough set feature selection is 97.34 and genetic feature selection is 98.22. Simulation results show that the proposed cross-layer approach aided by a combination of GA and SVM performs significantly better than other approach.
Keywords: Mobile Ad Hoc Networks, Intrusion Detection, Cross-Layer Design, Feature Selection, Rough Set Theory, Genetic Algorithm, Support Vector Machine
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #8, pp.71-79
Title of the Paper: Interference Cancellation and Complexity Reduction in Multi Stage Multi-User Detection
Authors: J. Ravindrababu, E. V. Krishna Rao, Y. Raja Rao
Abstract: Multi stage Parallel Interference Cancellation (PIC) technique gives good performance compared to Successive Interference Cancellation (SIC) method, but biased decision statistic and complexity problems are raised due to imperfect estimation of Multiple Access Interference (MAI) as number of stages increases. Partial Parallel Interference Cancellation (PPIC) technique is proposed to cancel the interference partially stage by stage to overcome biased problem. The complexity reduction for PIC detection is based on the convergence nature of interference cancellation which is called the Difference PIC (D-PIC) detection technique. In this paper we combine (PPIC and DPIC) these two techniques and propose a Multi stage multiuser Hybrid or PD-PIC using MMSE detector for performance improvement and complexity reduction compared to conventional PIC detector. The performance is degraded as the number of users’ increases in each technique. Here considering MMSE for first stage instead of matched filter.
Keywords: Multi-user detection, MMSE, MAI, SIC, PIC, PPIC, DPIC and PDPIC
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #7, pp.62-70
Title of the Paper: Performance Analysis of High-Rate Full-Diversity Space Time Frequency/Space Frequency Codes for Multiuser MIMO-OFDM
Authors: R. Shelim, M. A. Matin, A. U. Alam
Abstract: MIMO-OFDM has been recognized as one of the most promising techniques to support high data rate and high performance wireless systems. In particular, coding over the space, time, and frequency domains provided by MIMO-OFDM enables a much more reliable and robust transmission over the harsh wireless environment. In this paper, the authors provide an overview of space-frequency (SF) coding and space-time-frequency (STF) coding for MIMO-OFDM systems and compare the performance of different coding schemes. Performance results show that STF coding can achieve better coding and diversity gain in an end-to-end MIMO-OFDM system over broadband wireless channels.
Keywords: multiple-input multiple- output systems, multipath fading channels, multiple access channel (MAC), multiuser space time frequency (STF) coding, multiuser space-frequency (SF) coding
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #6, pp.51-61
Title of the Paper: Adaptive Beamforming Algorithms for Smart Antenna Systems
Authors: Amara Prakasa Rao, N. V. S. N. Sarma
Abstract: In this paper, Various evolutionary algorithms are used to adapt the weights of the smart antenna arrays to maximise the output power of the signal in desired direction and minimise the power in the unwanted direction. Different types of arrays (i.e., Linear, Circular, and Planar) are considered. Numerical results are presented to verify the improved convergence of the algorithms. Simulation results using different sets of antenna elements for different geometries are provided. In Least Mean Square algorithm, the convergence speed of the algorithm depends on the step size, which depends on the correlation matrix. With large eigen values spread, it converges slowly in a dynamic channel environment. This problem is solved by normalised least mean square and recursive least square algorithms. Simulation results show that the better adaptive beamforming algorithms for smart antenna systems in mobile communications.
Keywords: Constant Modulus Algorithm (CMA), Beamforming, Least Mean Square (LMS), Planar array geometry, Recursive Least Square (RLS), Smart antenna
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #5, pp.44-50
Title of the Paper: Performance Analysis of a Second Order FLL Assisted Third Order PLL for Tracking Doppler Rates
Authors: Ma Lu, Shi Liguo, Wang Zhugang
Abstract: The comprehensive analysis of the Spread Spectrum Responder (SSR) carrier tracking loops is presented. A mathematical model of a second-order FLL assisted third-order PLL is illustrated to study the performance in dynamics and noise. A fixed point method is used in the work to analyze the stable regions for the FLL, PLL and FLL assisted PLL. The Chapman-Kolmogorov (C-K) equation is utilized to express the steady-state Probability Density Function (PDF) of these three loops. The steady-state mean and variance are also be derived. At last, we discuss the optimizations for the combined loop due to the fact that the assisted tracking loop can be considered as an equivalent third-order PLL. This work will play an important role in designing the high dynamic carrier tracking.
Keywords: Spread Spectrum, Fixed Point Problem, Frequency Locked Loop, Phase Locked Loop, FLL Assisted PLL, Probability Density Function
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #4, pp.26-43
Title of the Paper: Enhanced Security Key Management Scheme for MANETS
Authors: Edna Elizabeth N., Subasree S., S. Radha
Abstract: (MANET) Mobile Ad hoc Network is a collection of wireless infrastructure less network. The topology of the network changes continuously. Due to the dynamic structure of MANETs, they are prone to various types of attacks. The traditional security solutions for MANETs are inadequate, hence security should be maintained at all the levels. To enhance security various schemes have been proposed. In this article the security is provided by two schemes namely the elliptic curve cryptography and the digital signature algorithm. Various points are generated from the elliptic curve of prime field and a point is chosen at random as a secret key. The public key generation centre forms the secured channel for transmitting the secret key to all the users in the MANET. Now the secret key to be shared is encrypted using the RSA algorithm. The keys before sending and receiving must be signed by the sender and verified by the receiver thereby authenticating each other. The encrypted secret key is concatenated along with the signature pair key and is sent through the secured channel. Thus the security is enhanced at various levels which prevent strong malicious attacks.
Keywords: HADS (Hash Asymmetric Digital Signature), ECC (Elliptic Curve Cryptography), DSA (Digital Signature Algorithm), BHA (black hole Attack)
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #3, pp.15-25
Title of the Paper: Performance Evaluation of Efficient Cooperative Multiple Input Multiple Output System Wireless Communication
Authors: Sindhu Hak Gupta, R. K. Singh, S. N. Sharan, Ashima Chawla
Abstract: In this paper, a novel technique known as Cooperative Communication in MIMO has been incorporated. This technique allows single antenna mobiles to have the benefits of MIMO systems. Numerical analysis and mathematical modeling is done for SISO with no cooperation, MIMO with no cooperation and MIMO with cooperation or Cooperative MIMO. Expressions for SNR, Outage probability and capacity over a channel link have been derived and simulated. A critical comparative analysis has been carried out between SISO with no cooperation, MIMO with no cooperation and Cooperative MIMO by evaluating and plotting various performance parameters. It has been demonstrated that Co-operative MIMO exhibits better performance in comparison to other two mentioned schemes.
Keywords: MIMO, Detect and forward protocol, SNR, Outage Probability, Capacity, Mutual Information
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #2, pp.9-14
Title of the Paper: AQ-DBPSK Modulation Performance Analysis for Wireless Sensor Communications
Authors: Vasanthi M. S., Dharmesh Kumar, Rama Rao T.
Abstract: Wireless sensor nodes have a limited amount of energy resource that determines their lifetime. So, Energy efficient modulation techniques are of paramount importance for wireless sensor communication (WSC). Also the type and behavior of the pulse shaping filters used, influences the performance of the modulation scheme. The Alternating Quadratures Differential Binary Phase Shift Keying (AQ-DBPSK) modulation scheme which is a variation of the Differential Binary Phase Shift Keying (DBPSK) scheme is simulated and a comparative study of communication performance metrics like Magnitude Error, Phase Error, Bandwidth Efficiency and Bit Error Rate (BER) for Binary Phase Shift Keying (BPSK), DBPSK and AQ-DBPSK using Raised Cosine and Root Raised Cosine filters are presented and analyzed. The results obtained show that tradeoffs can be made between spectral efficiency and energy efficiency by selecting the proper modulation scheme and using the appropriate value of excess bandwidth for the pulse shaping filter.
Keywords: Energy efficient, Wireless sensor Communications, Fading Channels, Pulse Shaping, Bandwidth Efficiency, Modulation, Bit Error Rate
WSEAS Transactions on Communications, ISSN / E-ISSN: 1109-2742 / 2224-2864, Volume 13, 2014, Art. #1, pp.1-8