WSEAS Transactions on Communications

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

Volume 11, 2012

Issue 1, Volume 11, January 2012

Title of the Paper: Cross-layer Packet Dependent OFDM Scheduling Based on Proportional Fairness

Authors: Hua Hou, Gen-Xuan Li

Abstract: This paper assumes each user has more than one queue, derives a new packet dependent proportional fairness power allocation pattern based on the sum of weight capacity and the packet’s priority in users’ queues, and proposes 4 new schemes of cross-layer packet dependent OFDM scheduling for heterogeneous classes of traffic based on proportional fairness. Scenario 1, scenario 2 and scenario 3 lead respectively artificial fish swarm algorithm, self-adaptive particle swarm optimization algorithm and cloud adaptive particle swarm optimization algorithm into sub-carrier allocation in packet dependent proportional fairness scheduling, and use respectively new power allocation pattern, self-adaptive particle swarm optimization algorithm and population migration algorithm to allocate power. Scenario 4 uses greedy algorithm concerning fairness to allocate sub-carriers, and uses new power allocation pattern to allocate power. Simulation indicates scenario 1, scenario 2 and scenario 3 raise the system’s total rate on the basis of undertaking the fairness among users’ rates and average packet delay; scenario 4 not only meets the demands of users’ rates and average packet delay, but also improves the fairness among users’ rates.

Keywords: Multi-user OFDM, Scheduling, Proportional fairness, Swarm intelligence algorithm, Artificial fish swarm algorithm, Particle swarm algorithm, Population migration algorithm

Title of the Paper: Low-Energy-Transmission of Data on Submicron Interconnects

Authors: A. Mahdoum, L. Hamimed, M. Louzri, M. Saadaoui

Abstract: We present in this paper a CAD tool that aims at designing low-energy buses. The Graphical User Interface (GUI) we developed manages many techniques dealing with the addressed problem: simple coding, coding subject to fixed / dynamic probabilities and an enhanced dynamic probabilities- based technique. Moreover, this environment allows tuning the parameters of data encoding / decoding and is able to generate different gains by varying the size of the bus transferring the encoded data. Finally, this tool can be easily configured to integrate new coding techniques and use one of them when favorably compared against the other techniques.

Keywords: Communications Submicron interconnects Energy dissipation Data transfer

Title of the Paper: IPSD: New Coverage Preserving and Connectivity Maintenance Scheme for Improving Lifetime of Wireless Sensor Networks

Authors: A. Balamurugan, T. Purusothaman

Abstract: In many applications it is necessary to have some guarantees on the coverage, connectivity and lifetime of the Wireless Sensor Networks(WSN). Coverage problem is regarding how to ensure that each of the points in the region to be monitored is covered by the sensors. In maximizing coverage, the sensors need to be placed not too close to each other so that the sensing capability of the network is fully utilized and at the same time they must not be located too far from each other to avoid the formation of coverage holes. On the other hand from connectivity point of view, the sensors need to be placed close enough so that they are within each other communication range thus connectivity is ensured. Once coverage and connectivity are ensured, the overall lifetime of the network gets increased thereby improving the quality of service (QoS) of the Wireless Sensor Network (WSN). The concept of Integer Programmed Sensor Deployment (IPSD) scheme is being proposed, with a set of relay nodes a triangular lattice is formed by the grid based approach thus providing maximum coverage and connectivity. Integer Linear Programming (ILP) is brought into existence for eliminating the unused relay nodes thereby enhancing the coverage and connectivity with minimum number of relay nodes. Simulation is performed using NS-2 and the results shows that the proposed scheme provides better results in large scale WSN with improved coverage and connectivity.

Keywords: WSN, ILP, relay node, coverage, connectivity

Title of the Paper: Video Multicast Over Wireless Ad Hoc Networks

Authors: Osamah S. Badarneh, Michel Kadoch

Abstract: Existing video multicast routing protocols in wireless ad hoc networks have been developed under the assumption that destination nodes wish to receive all the information sent by the multicast source, i.e., they do not support heterogeneous destinations. This paper addresses the problem of video multicast for heterogeneous destinations in wireless ad hoc networks. Multiple Description Coding (MDC) is used for video coding. MDC generates multiple independent bit-streams, where the multiple bit-streams are referred to as multiple descriptions (MD). Furthermore, MDC enables a useful reproduction of the video when any description is correctly received. Specifically, we propose three novel multiple multicast trees routing protocols. The first protocol constructs multiple disjoint multicast trees and assigns MD video in a centralized fashion, and is referred to as Centralized MDMTR (Multiple Disjoint Multicast Trees Routing). The second protocol is a variant of Centralized MDMTR. We refer to it as Sequential MDMTR. The main difference between Sequential MDMTR and Centralized MDMTR is that, Sequential MDMTR sequentially assigns MD video to the destination nodes. In order to reduce construction delay and routing overhead, we further propose Distributed MDMTR protocol. Both protocols, Centralized MDMTR and Distributed MDMTR, exploit the independent-description property of MDC along with multiple disjoint paths to increase the number of assigned video descriptions to each destination. We extensively evaluate our proposed protocols by simulations and show that they outperform the existing work.

Keywords: Video multicast, wireless ad hoc networks, multiple description coding, heterogeneous destinations

Issue 2, Volume 11, February 2012

Title of the Paper: An Integrated Cross Layer Approach for Multimedia Streaming using Multipath and Multiple Description Coding in Mobile Ad-Hoc Networks

Authors: N. Gomathi, P. Seethalakshmi, A. Govardhan

Abstract: The objective of this paper is to propose a novel method for enhancing the QoS of multimedia applications in mobile adhoc networks by using Multipath and Multi Description Coding. The enhancement is achieved by implementing the Multi Description Coding (MDC) at application layer along with Connectionless Light Weight Protocol (UDPLite) in transport layer and multipath at network layer. This approach achieves an increase of 12.75% in Peak Signal to Noise Ratio (PSNR) which is an improvement in PSNR as compared to the conventional methods.

Keywords: MANETS, QoS, Multiple Description Coding (MDC), UDPLite, Multipath Transport, Video Streaming, PSNR

Title of the Paper: Synchronization and Cell Search Algorithms in 3GPP Long Term Evolution Systems (FDD mode)

Authors: Abdo N. Gaber, Loay D. Khalaf, Ahmad M. Mustafa

Abstract: In this paper initial downlink synchronization (sync) and cell identification algorithms for the 3rd generation partnership project (3GPP) long term evolution (LTE) systems are presented. The frequency division duplex (FDD) mode is used in the downlink radio frame structure. A user equipment digital receiver architecture is proposed. The orthogonality of signals in orthogonal frequency division multiplexing (OFDM) may be lost due to some impairments such as frequency, time, and phase offsets. Therefore, major parts of this research are involved in restoring the orthogonality at the user equipment (UE) by using some techniques to estimate the sync parameters, and to detect cell identity among candidate cells based on sync signals. A Farrow structure interpolator is used to compensate the fractional timing offset. Both inter site synchronous and inter site asynchronous networks are presented. Computer simulations are used to demonstrate the performance of the proposed schemes with multipath Rayleigh fading channel, frequency offsets, timing offsets, and additive white Gaussian noise (AWGN). Results show high probability of cell identification in a very short time 20 ms in both multi cell model scenarios, especially when multiple input multiple output (MIMO) technique, oversampling at the UE, and high order Farrow structure interpolator are used.

Keywords: 3GPP LTE, OFDM, MIMO, Frequency and Time Synchronization, Cell Search

Title of the Paper: A New Adaptive Model for Throughput Enhancement and Optimal Relay Selection in IEEE 802.16j Networks

Authors: D. Satish Kumar, N. Nagarajan

Abstract: IEEE 802.16 standard is created to compete with cable access networks. In the beginning end users are immobile and have a line of sight with base station, now it moved to mobile non line of sight (NLOS) with the new standard IEEE 802.16e and IEEE 802.16j. The new IEEE 802.16j standard which is an amendment to IEEE 802.16e is mobile multi hop relay (MMR) specification for wireless networks. In this paper we have proposed a new adaptive model for transparent mode IEEE 802.16j MMR networks and studied about the throughput enhancement, optimal relay placement and spatial reuse techniques. We have used four mobile stations (T-MS) connected to transparent mode base station (TMR-BS), which are moving at a speed of 20 m/sec. The T-MS are initially placed near to TMR-BS and are moving away from TMR-BS. The average throughput achieved without relay T-RS is 792.045913 Kbps and the average throughput achieved with relay TRS is 1261.856667 Kbps. There is 37.2318% increase in the throughput by placing transparent mode relays TRS at suitable position.

Keywords: IEEE 802.16j, relay modes, Optimal relay placement, WIMAX, NCTUns

Title of the Paper: Code Scattering and Reduction in OVSF Code Blocking for 3G and beyond Mobile Communication Systems

Authors: Neeru Sharma, Davinder S. Saini

Abstract: Scattered vacant codes in Orthogonal Variable Spreading Factor (OVSF) code based 3G and beyond WCDMA wireless networks leads to code blocking which further gives call blocking. The paper proposes four single code assignment schemes to reduce code scattering. The use of assignment scheme depends upon the type of input calls. The code reservation assignment (CRA) is used to efficiently handle one or higher rate class calls. It assigns priority number to the children of priority class codes such that the future availability of vacant codes in the priority layer is the highest. The remaining three code assignment schemes favors low to medium calls. The code assignment using group leaders uses busy codes (capacity) under predefined leaders to handle future calls. The code blocking in group leader approach can be reduced further if the used capacity of all the parents of the eligible vacant codes is examined and the code whose parent has maximum used capacity is used for new call. In adjacent vacant codes grouping scheme, the eligible vacant codes are listed to find code with least adjacent vacant codes. If unique result does not exists, the code (among the codes producing same adjacent vacant codes) with the least elapsed time of the busy neighbors is used for incoming call.

Keywords: OVSF codes, code/call blocking, OVSF assignment, OVSF reassignment, OVSF code scattering

Issue 3, Volume 11, March 2012

Title of the Paper: A Cost Effective Approach for WDM Network Protection under Critical Duct Constraints

Authors: D. Sheela, C. Chellamuthu

Abstract: In this paper, protection strategies of WDM networks are viewed from a cost perspective. The goal is to minimize the network cost while ensuring the network survivability. In WDM networks, multi fibers are kept in a duct and that duct can be treated as a link SRLG (shared risk link group). With the increase in size and number of shared risk link groups, capacity efficiency of shared-path protection decreases due to SRLG-disjoint constraints. As a result, a full SRLG failure protection is no longer a practical protection scheme. In a network, there are always some links with higher degree of usage compared to other links in the network. In the event of failure of such links, the survivability of the network is severely affected and these links are called as critical links. The ducts that carry these critical links are designated as critical ducts. This paper proposes an approach in which partial critical duct -disjoint backup path is provided by choosing the backup path with least number of critical ducts to make the impact of duct failures as low as possible. A dual-duct infrastructure is presented for these critical ducts as a solution to reduce the resource requirement and to provide flexibility in selecting the backup paths. Simulation results show that this scheme offers better survivability against both single duct and double duct failures with overall reduction in network cost.

Keywords: Wavelength division multiplexing, Dimensioning, Network protection, Shared risk link group, Topology, Critical ducts

Title of the Paper: Analysis of Subcarrier and Antenna Power Allocation for MIMO WPMCM System with Sphere Decoder

Authors: R. Deepa, K. Baskaran

Abstract: In order to achieve the efficient usage of the available bandwidth in wireless environments, the best method for real time application would be combining Multi- Input Multi-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) together. The OFDM implemented by using IFFT’s and FFT’s have major drawbacks like ISI (intersymbol interference), Time and Frequency Synchronization and Carrier Frequency Offset. To alleviate the above problems wavelet transform is used to generate the orthogonal carrier. This paper investigates joint subcarrier and antenna power allocation in WPMCM system. The transmit (antenna) power is allocated for the proposed combination using the Lagrangian method and compared with the conventional power allocation scheme. Existing sub-optimal techniques either use equal power allocation and perform only subcarrier allocation or handle subcarrier and power allocation separately. In this paper, we propose an algorithm that performs joint subcarrier and power allocation to reduce the BER under a total power constraint.

Keywords: MIMO-WPMCM, antenna, sub-carrier power allocation, sphere decoder

Title of the Paper: Iterative Multicarrier Detector and LDPC Decoder for OFDM Systems

Authors: Shu-Ming Tseng, Yueh-Teng Hsu, Yi-Rung Peng

Abstract: In this paper, we propose iterative soft-input soft-output (SISO) multi-carrier detection (inter-carrier interference cancellation) and LDPC decoding of the OFDM system in the mobile channel. The proposed SISO multi-carrier detection and sum-product decoding of the LDPC-coded OFDM system can achieve better error rate performance than previous SISO multi-carrier detection and BCJR decoding of convolutional coded (CC)-OFDM systems in mobile channels. The simulation results show that the second iteration improves the performance significantly and the gain of the third iteration is less. The advantage of LDPC over CC is more significant when the codeword is longer. With channel estimation errors, the proposed scheme degrades by 0.5 dB for the 3rd iteration. In addition, the proposed LDPC-OFDM scheme has lower computational complexity than the CC-OFDM one.

Keywords: inter-carrier interference, turbo principle, OFDM, LDPC, computational complexity

Issue 4, Volume 11, April 2012

Title of the Paper: OVSF Code Slots Sharing and Reduction in Call Blocking for 3G and Beyond WCDMA Networks

Authors: Davinder S. Saini, Vipin Balyan

Abstract: OVSF (Orthogonal Variable Spreading Factor) codes are used in WCDMA uplink and downlink transmission for multirate traffic. The orthogonal property of these codes leads to code blocking and new call blocking. Two code (or slot) sharing assignment schemes are proposed to reduce the effect of code blocking using OVSF and NOVSF (non blocking OVSF) codes. The schemes favor the real time calls as they are given higher priority in all 3G and beyond networks. The benefit of the proposed scheme is the better handling of non quantized rates compared to other novel single code and multi code assignment schemes. Both single code and multi code options are analyzed for OVSF as well as NOVSF codes. Simulation results are discussed to show the benefits of the proposed scheme.

Keywords: OVSF codes, slots, time sharing, multiplexing, single code assignment, multi code assignment, real time, code blocking

Title of the Paper: A Framework for Configuration and Management of Quality-of-Service (QoS) in Wireless Zigbee Networks

Authors: P. Anitha, C. Chandrasekar

Abstract: The low cost, low power, low complexity Zigbee defined in IEEE standard 802.15.4 for low rate wpan’s upon MAC and physical layer. The objective is to make possible of incalculable process among next generation devices with small transmitters and agree to communicate between devices with central PAN coordinator. Thus zigbee desires efficient routing ptotocol to deal with lowest amount of energy expenses and highest network life time. In this paper zigbee provides cross layer network protection and application service carried out with hierarchical cluster tree formation. Mac layer utilize the cluster tree formula to establish tree configuration subsequently that cluster table taken to the routing layer protocol of CLZBRP (Cross Layer Zigbee Based Routing Protocol). Here CLZBRP is compared with AODV (Ad Hoc On-demand Distance Vector Routing) and TBR (Tree-Based Routing) with QOS.

Keywords: Cross-Layer Design, CLZBRP, Cluster table, Energy, Zigbee, TBR, AODV, QoS

Title of the Paper: Interference-Aware Subcarrier Allocation in a Correlated MIMO Downlink Transmission

Authors: Rosdiadee Nordin

Abstract: The demand for high data rate in wireless communication has increased dramatically over the last two decades. Multiple-Input Multiple-Output (MIMO) transmission is one of the efficient ways to transmit high data rate is by employing multiple antenna configuration at both the transmitter and the receiver. One of the MIMO scheme, known as Spatial Multiplexing (SM), relies on the linear independence data streams from different transmit antennas to exploit the capacity from the fading channels. Consequently, SM suffers considerably from the effect of spatial correlation, thus becomes the limiting factor in achieving the capacity benefit that SM offers. In an attempt to increase the robustness of the SM transmission for deployment in a wide range of correlated channels, the use of interference-aware subcarrier allocation is proposed. The Signal-to-Interference-and-Noise Ratio (SINR) metric is used as the performance metric to determine subcarrier quality which can then be utilized in the allocation process in order to exploit the multiuser diversity gain that can be offered in an Orthogonal Frequency Division Multiple Access (OFDMA) system. From the simulation results, it is shown that the proposed subcarrier allocation has improved the BER performance of SM transmission in highly correlated channels environment.

Keywords: Correlated channel, SINR, Interference, MIMO, OFDMA, Spatial multiplexing, Spatial correlation, Subcarrier allocation

Issue 5, Volume 11, May 2012

Title of the Paper: Reduced Complexity Max Norm Based PAPR Optimization in OFDM Systems

Authors: M. Palanivelan, Sheila Anand

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is a suitable multicarrier modulation scheme for high speed broadband communication systems. OFDM provides bandwidth efficiency and robustness against multipath fading channels, but is sensitive to nonlinear effects due to the high Peak-to-Average Power Ratio (PAPR) of the transmitted signal. The reduction in PAPR is desirable in order to obtain power efficiency and to increase BER performance. This paper proposes an efficient Reduced Complexity Max Norm (RCMN) algorithm for optimizing the PAPR of the OFDM signals. The proposed technique avoids the use of additional Inverse Fast-Fourier Transform (IFFT) as compared to Selective Level Mapping (SLM) and Partial Transmit Sequence (PTS) and hence reduces the computational and phase search complexity. In addition, as compared to other probabilistic schemes such as SLM and PTS, the proposed scheme does not require the transmission of Side Information (SI) to the receiver, which provides better bandwidth utilization. The proposed scheme has been compared with SLM and PTS schemes and the results show that the RCMN improves PAPR optimization with less computational and phase search complexity.


Title of the Paper: A Two State Proactive Transport Protocol for Satellite Based Networks

Authors: Mohanchur Sarkar, K. K. Shukla, K. S. Dasgupta

Abstract: In satellite-based networks, current TCP Protocols have lower throughput performance mainly due to the effect of long propagation delays and high link error rates. In this paper, a new congestion control protocol for satellite-based networks is proposed. The protocol uses a proactive approach and is composed of novel ideas like Proactive Slow Start, Proactive Congestion Avoidance and Decision based Error handling policies that are combined with traditional TCP algorithms, like Fast Retransmit. The mainstay of our protocol is the nature of the RTT pattern can give us indication of an incipient congestion in the network. This changing pattern of RTT is used to differentiate between congestion and link error, thus avoiding unnecessary rate throttle. In the initial phase, necessary augmentation of ns2 simulator pertaining to the proposed protocol has been carried out. This was essential to create a necessary test bed for exhaustive simulation of the protocol considering a GEO network, with different congestion level and packet error rate. Simulation results show that the protocol always outperforms other TCP protocols in terms of goodput and an improvement of 80% to 120% is observed, especially when the packet error rate is very high. Evaluation of the protocol shows a high fairness property and excellent adaptability to high levels of congestion and channel errors.

Keywords: TCP, Satellite, UDP, Peach, Reno, SACK, Vegas

Title of the Paper: Construction Methods of Closed Users Group Using Multi-Party Protocol

Authors: Masao Tanabe, Keita Sugiyama, Masaki Aida

Abstract: In recent years, the Internet has become the most important infrastructure in the information society. Until now, a client-server system such as e-mail or WWW that is offered by a fixed service provider has played an important role. However, in such client-server systems, it is impossible to continue to provide services when the servers are halted by some failure. For this reason, a pure Peer-to-Peer (P2P) network, in which a user also acts as a provider, has lately attracted considerable attention as a new commercial infrastructure, because it enables its users to provide a service without a dedicated server. However, it is difficult to provide security on a pure P2P network because each terminal on the network has the same privilege. In this paper, we study a construction method of a Closed Users Group (CUG) without any administration methods which can control user access to certain applications on a pure P2P network. In our method, we assume that each member of a CUG has a certification which is issued by a certification authority on a public key infrastructure (PKI) that enables members to communicate safely. We realize this PKI on a P2P network using a multi-party protocol. In addition, we study the reliability issues involved in this method and propose some methods of issuing a certification to a new member. Finally, we discuss strong points and applications of one of these methods.

Keywords: Closed Users Group, Multi-party protocol, Certification authority, P2P network, Public key infrastructure, I2P Network

Issue 6, Volume 11, June 2012

Title of the Paper: One and Two Dimensions Unequally Array Pattern Synthesis with the use of a Modified Particle Swarm Optimization Algorithm

Authors: Hichem Chaker, Sidi Mohamed Meriah, Fethi Bendimerad

Abstract: A computationally efficient global optimization method, the adaptive particle swarm optimization (APSO), is proposed for the synthesis of uniform and Gaussian amplitude arrays of two cases, i.e., the prior constraint in the synthesis of the element positions for both the cases is dmin = 0.5 λ, where dmin is the minimum distance between two adjacent elements. The upper limit in the distance between the elements, dmax is varied from 0.5λ to 0.6λ for the first case and from 0.5λ to λ for the second case. The proposed iterative method aims at linear and planar array and the optimization of phases- positions by minimizing the side-lobes level and respecting a beam pattern shape. Selected examples are included, which demonstrate the effectiveness and the design flexibility of the proposed method in the framework of the electromagnetic synthesis of linear and planar antennas arrays.

Keywords: Adaptive particle swarm optimization, unequally spaced linear and planar arrays antennas

Title of the Paper: Encoding Schemes for Memory Efficient Quasi Cyclic Low Density Parity Check Codes

Authors: Mohammad Rakibul Islam, Syed Iftekhar Ali

Abstract: Low Density Parity Check (LDPC) codes have attracted current researchers due to their excellent performance and capability of parallel decoding. One major criticism concerning LDPC codes has been their apparent high encoding complexity and memory inefficient nature due to large parity check matrix. This led the researchers to move into a memory efficient LDPC called Quasi-Cyclic (QC)-LDPC which shows the similar performance as LDPC does. This review gives a theoretical and analytical survey on different encoding schemes for QC-LDPC codes. The encoding schemes are categorized in three broad categories. These schemes are then analyzed under those three broad fields. Also different encoding schemes are compared.

Keywords: LDPC, QC-LDPC, efficient encoding, Richardson, Low complexity

Title of the Paper: Design of a Quasi-Cyclic LDPC Decoder Using Generic Data Packing Scheme

Authors: Jinlei Chen, Yan Zhang, Xu Wang

Abstract: This paper proposed a generic data packing scheme for quasi-cyclic LDPC codes decoder which has two advantages. Firstly, in this scheme no shift network is needed, it greatly reduces the area of the LDPC decoder. Secondly, in this scheme, all the messages in a row can be accessed from memories in one cycle, it increase the throughput of LDPC decoder. A LDPC decoder architecture using the data packing scheme is proposed. Based on this architecture, a multi rate decoder that supports all code rates and all code lengths in IEEE 802.16e standard is implemented using a SMIC 0.18μm CMOS technology. Compared to the existing LDPC decoder which uses the same parallel check node process unit, the proposed decoder has nearly the same throughput and achieves saving of 16% in area. Synthesis results also show that the area and throughput of the proposed decoder increases linearly with the number of process units.

Keywords: LDPC decoder, message packaging, alignment unit, layered, parallel processing, QC codes

Issue 7, Volume 11, July 2012

Title of the Paper: Real Time Position Location & Tracking (PL&T) Using Prediction Filter and Integrated Zone Finding in OFDM Channel

Authors: Niraj Shakhakarmi, D. R. Vaman

Abstract: The nature of pre-determined and on-demand mobile network fabrics can be exploited for Position Real time Location Tracking (PL&T) of radios and sensors (nodes) for Global Positioning System (GPS) denied or GPS-free systems. This issue is addressed by a novel system of integrating zone finding and triangulation method for determining the PL&T of nodes when MANET is employed based on using directional antennas for radio communications. Each mobile node is switched dynamically between being a reference and a PL&T target node to improve the accuracy of predicting the PL&T of each node. This paper presents the Baseline PL&T with predictive Kalman filter and Integrated zone based PL&T algorithm design that integrates zone finding and triangulation method. The performance of the proposed algorithm is analyzed in Rayleigh and Rician based on the Orthogonal Frequency Division Multiplexing (OFDM) system using efficient Interleaving-KV sample coding & error correction scheme under multipath faded channel.

Keywords: Real time, Position Location & Tracking, Prediction Filter, Integrated Zone Finding, OFDM Channel

Title of the Paper: A Novel QoS Aware RWA with Dedicated Path Protection Consideration for All Optical Networks

Authors: K. Ramesh Kumar, R. S. D. Wahida Banu

Abstract: In all optical networks, signals has to travel over long distances and physical layer impairments (PLI) accumulate as regeneration capability is not available. During transmission, Quality of Service (QoS) of signals as measured by their Bit Error Rates (BER) is degraded due to propagation in the fibers, amplifier noise, and crosstalk between channels arising from the switches and demultiplexers which cannot be removed at the physical layer. It is possible to mitigate physical layer effects at the network layer using appropriate QoS aware Routing and Wavelength Assignment (RWA) algorithms. There are only few Offline RWA algorithms that consider dedicated path protection. In this paper an offline RWA Scheme called WpDp-MaMiQ is presented with dedicated path protection consideration that mitigates PLI. Simulations show that the proposed algorithm performs better in terms of blocking rate and BER.

Keywords: Routing and Wavelength Assignment (RWA), Physical layer impairments, Optical networks, Dedicated path protection, Cross talk, QoS aware, Blocking probability

Title of the Paper: Enhanced Energy Efficient Privacy Provisioning in WSN

Authors: Manjusha Pandey, Shekhar Verma

Abstract: Privacy provisioning along with the core functionality of WSN including routing of the sensed data through predetermined optimized routes to the base station which produces pronounced traffic near the sink node adding up to the revelation of either location of direction of location of base station is one of the major research challenges in WSN. The proposed privacy provisioning scheme aims to optimize energy consumption for privacy provisioning in WSN. The traffic patterns may be disguised by introducing fake packets to the generated traffic of original data and a time to live parameter is introduced to execute lesser energy consumption. Earlier also many anti traffic analysis strategies have been proposed and implemented with the same objective But the inclusion of fake packets adds up communication overhead and higher energy consumption in the network as a whole. Hence the problem undertaken in the current research effort is to optimize the energy consumption at the node level for fake packet generation by using residual energy of each node. The energy optimization has been done using the two fold privacy provisioning a) generation of fake packets by the nodes having larger residual energy and avoiding nodes having residual energy less than a threshold value. b) The fake packet generated has an associated TTL (Time to Live) that can be constant or based on the residual energy of nodes.

Keywords: WSNs, wireless sensor networks, Privacy in WSN, Traffic analysis, energy efficiency

Issue 8, Volume 11, August 2012

Title of the Paper: QoS Based OVPN Connection Set Up and Performance Analysis

Authors: Santos Kumar Das, Dhanya V. V., Sarat Kumar Patra

Abstract: Due to high demand of optical virtual private network (OVPN) connection setup with guaranteed quality of service (QoS) requirement, it is necessary to provide such application by the provider network. In order to support this we propose a QoS based OVPN connection set up mechanism over WDM network to the end customer, which also maintains the minimum blocking probability. The proposed WDM network model can be specified in terms of QoS parameters such as bandwidth and delay. We estimated those QoS parameters based on available resources and QoS requirements in terms of quality factor (Q-Factor). In this mechanism the OVPN connections also can be created or deleted according to the availability of the resources. In this paper we have considered the effect of polarization mode dispersion for the computation of Q-Factors which is prominent effect at high speed networks. The goal of the work is to dynamically provide a best OVPN connection during frequent arrival of connection requests with QoS requirements.

Keywords: OVPN Connection, QoS, Q-Factor, Disjoint Path, Shortest Path, Blocking Probability

Title of the Paper: Adaptive Three-Layer Weighted Links Routing Protocol for Secure Transmission over Optical Networks

Authors: Mohammed Al-Momin, John Cosmas, Saman Amin

Abstract: Bandwidth, latency and data security are the three major factors that affect the Quality of Service (QoS) for any computer network. Different applications running on a network have different requirements of these three factors, and dealing with all applications types in a similar manner is an inefficient approach. This paper proposes a routing protocol that recognizes the type of traffic and routes it accordingly to provide the optimal QoS. Different data types are to be routed through different routes to satisfy the preferred QoS requirements of these data types. The weights of the network’s links were partitioned in this paper into three layers to accommodate these three QoS requirements factors.

Keywords: QoS, Adaptive Weighted Routing, Latency, Secure Transmission, Optical Network

Title of the Paper: Analysis of Indoor Wireless Infrared Optical CDMA LAN Using Prime Codes

Authors: R. Kanmani, K. Sankaranarayanan, F. Infant Princy

Abstract: In wireless optical system, CDMA suits well for high bit rate systems where good security is needed and mobility is not important. It would be economical when compared to radio frequency band and much safer since there is no electromagnetic effect. Infrared systems are used for its widest bandwidth and are not affected by radio transmission. The advantage of the prime code and the security issues in choosing the coding technique is noted. Prime codes would be much better than optical orthogonal code because of its heavier code weight. The error probability of prime codes and OOC is compared in infrared wireless OCDMA network. The bit error probabilities of Optical CDMA system using prime sequence codes are analyzed. We employ OOK and PPM as the modulation schemes and derive the bit error probability of the systems. The transmission power versus BER and number of user versus BER for various signals is calculated and the results are analyzed.

Keywords: CDMA-Code Division Multiple Accesses OOC –Optical Orthogonal Code, OCDMA-optical CDMA, Prime Codes, wireless infrared, OOK-On Off Keying, BPPM -Binary Pulse Position Modulation

Issue 9, Volume 11, September 2012

Title of the Paper: Improving Connectivity and Resilience using ECC based Key Predistribution for Deployment Knowledge based WSN

Authors: R. Kishore, S. Radha, L. Cherlyflar

Abstract: Wireless Sensor Networks consist of small nodes with sensing, computation and communication capabilities, often deployed in remote inaccessible areas to interact with the environment and forward the measured event to the base station, thus posing several possibilities of physical attacks. Hence security becomes an important issue in wireless sensor networks. For resource constrained environments like wireless sensor networks key predistribution is found to be better choice. Another significant information regarding network is the deployment knowledge which can be used to improve the performance of the key predistribution schemes. Deployment knowledge offers numerous advantages when used in resource constrained environments, achieving better storage, better resilience to node capture, minimizing the number of keys and reduce network overhead. The main objective of this paper is to propose a novel scheme where keys are generated using Elliptic Curve Cryptography and predistributed into the nodes. Nodes are deployed in the area of interest considering hexagonal deployment knowledge and the links are formed based on the common keys of private key ring in each node. The performance of the system is evaluated in terms of resilience and connectivity. The results show that the connectivity and resilience of the network is better when compared to other existing key predistribution schemes.

Keywords: Security, Key Predistribution, Elliptic Curve Cryptography, Elliptic Curve Points, Connectivity, Resilience

Title of the Paper: Secure Communication Method Using Invitation Process in Mobile Ad Hoc Networks

Authors: Masao Tanabe, Masaki Aida

Abstract: The importance of security in mobile ad hoc networks has been recognized for many years, and many secure routing methods have been proposed in this field. This paper discusses major security attacks in mobile ad hoc networks and focused on resource exhaustion attacks as the most important security issue. We reviewed countermeasures including the methods that we proposed before for these attacks and propose a highly secure communication method that is based on a very efficient invitation process for handling new members. We evaluate the method from the viewpoint of implementation and make it clear that it is more useful than the methods that we proposed before as a countermeasure against resource exhausting attacks. We also study and evaluate the method from the viewpoint of stability and clarify that it makes the network stable on condition that it decreases the members who are expelled from the network when the attacker is found.

Keywords: Mobile ad hoc network, Security, Communication method, Community, DDoS attacks

Title of the Paper: Secured System against DDoS Attack in Mobile Adhoc Network

Authors: Arunmozhi Annamalai, Venkataramani Yegnanarayanan

Abstract: The risks to users of wireless technology have increased as the service has become more popular. Due to the dynamically changing topology, open environment and lack of centralized security infrastructure, a mobile ad hoc network (MANET) is vulnerable to the presence of malicious nodes and to ad hoc routing attacks. There are a wide variety of routing attacks that target the weakness of MANETs. This paper focuses on mobile ad hoc network's routing vulnerability and analyzes the network performance under two types of attacks, flooding attack and black hole attack that can easily be employed against the MANETS. The resistive schemes against these attacks were proposed for Ad hoc on demand Distance Vector (AODV) routing protocol and the effectiveness of the schemes is validated using NS2 simulations.

Keywords: Security, Defense, Mobile adhoc network, Denial of service, Flooding attack, Black hole attack

Title of the Paper: An Adaptive Energy Efficient Model for wireless Ad Hoc Networks

Authors: D. K. Lobiyal, Yaser Mahmood A. Hamid

Abstract: Several transmit power control MAC protocols have been designed primarily to reduce the energy consumption in wireless ad hoc networks. On the other hand, many adaptive rate MAC protocols have been mainly proposed to improve the network throughput. Recently, very few MAC protocols have been suggested by combining the transmit power control and adaptive rate in one algorithm. In this paper, we proposed a new energy efficient MAC protocol for the Distributed Coordination Function (DCF) IEEE 802.11b based ad hoc networks which also maximizes the overall network throughput. We call this protocol s Traffic Sensing adaptive Rate Power (TSRP) control MAC protocol. In our technique, the MAC protocol selects the best rate-power combination for each data frame which can achieve the required Signal to Noise Ratio (SNR) at the receiver, maximize throughput and save energy. The basic idea of the TSRP protocol is that rather than just matching the channel condition, the sender sense outgoing traffic based on the traffic load and the queue condition. We have simulated the TSRP MAC protocol for two different scenarios – single flow single hop and two source two flows. The simulation results show that TSRP saves more energy saving and achieves higher throughput than IEEE 802.11b.

Keywords: Adaptive rate, Ad hoc Networks, MAC protocol, power control, TSRP, IEEE 802.11 DCF

Issue 10, Volume 11, October 2012

Title of the Paper: Efficient Signal Quality Improvement Approach for Wideband VoIP System in Pervasive Environment

Authors: H. P. Singh, Sarabjeet Singh, Jasvir Singh

Abstract: Voice over Internet Protocol (VoIP) is a the best alternative to the traditional voice communication system, since VoIP system converges the data, voice and video data and reduces the cost of call transmission by passing packets through the available bandwidth through internet protocol. Since the environmental noise may affect the intelligibility of the speech signal, so it is desirable to use the speech processing methods to enhance the quality and intelligibility of the speech signal. The proposed scheme, interpolated finite impulse response (IFIR), is implemented as post-processor after decoding the signal in wideband VoIP system. The performance of the proposed scheme is evaluated for various types of noises at different network conditions. The results of the proposed scheme are measured with the wideband-extension to perceptual evaluation of speech quality measurement (WB-PESQ) for wideband signal. The performance of the proposed system is compared with the existing techniques for quality improvement in VoIP system. The results show much improvement in speech quality with proposed scheme in comparison to other similar schemes.

Keywords: Wideband VoIP, AMR-WB, IFIR, Background Noise

Title of the Paper: An SLM based PAPR Reduction Method using New Volterra Predistorter Model in the OFDM System

Authors: Pankaj Kumar Sharma, R. K. Nagaria

Abstract: Orthogonal frequency division multiplexing (OFDM) is a strong candidate for future wireless communication because it is marked by its higher frequency multiplicity and greater immunity to multipath fading. However, the main drawback of OFDM is high peak-to-average power ratio (PAPR), which leads to power inefficiency and requires expensive high power amplifier (HPA) with very good linearity. In this paper, we have propose SLM with volterra series models (VSM) technique to linearize the high power amplifier (HPA).

Keywords: OFDM, PAPR, SLM, VSM, Nonlinear HPA

Title of the Paper: The Effect of Interference on Bluetooth Data Exchange over WLAN

Authors: M. Abu Shattal, Abdel-Rahman Al-Qawasmi

Abstract: The paper focuses on studying Bluetooth Wireless Personal Area Network (WPAN) and Wireless Local Area Network (WLAN) technologies to make Bluetooth data exchange over WLAN applicable. In particular, it addresses the problem of using WLAN coverage area to exchange data between two Bluetooth devices connected to different piconets. To achieve this goal, we propose a new approach of Bluetooth-WLAN integration taking in account the effect of Interference. Problem arising from this integration can be solved using two approaches. Hardware solution when an electronic design for a hardware chip can be offered to support WLAN and the Bluetooth data exchange technologies between two wireless networks. Such chip would be good enough to work as fast as possible but it will suffer from incompatibility with the current technologies such as Mobile phones, PCs, and laptops. The second approach is the software solution when software development for WLAN-WPAN integration can maintain the capabilities of current devices for both technologies. The work proposes different simulation Models developed to simulate the integration process, to study the effect of interference in different locations in Bluetooth-WLAN Integrated Network (BWIN). Simulation results show the ability of data exchange over WLAN considering architecture and interfering aspects.

Keywords: Bluetooth, WLAN, Integrated network, interference, data exchange.

Title of the Paper: The RAM-based Web Proxy Servers

Authors: Kin-Yeung Wong, Ka-Chon Lai

Abstract: The conventional web proxy servers use hard disk as their primary cache storage. However, as disks use mechanical operations, they are typically the slowest component of the servers. Though, in the last decade, various solutions have been proposed to improve the proxy performance, disks are still the performance bottleneck. Consider that the mainstream operating systems are 64-bit and the cost of memory has become economical in recent years. In this paper, a proxy server using main memory as the primary cache storage is proposed. Analytical results show that the ram-based proxy servers effectively eliminate the performance bottleneck of disk, and allow systems to scale well for higher browser rates.

Keywords: Web Proxy, Web caching, Web Traffic, Storage Design, Performance Evaluation

Issue 11, Volume 11, November 2012

Title of the Paper: A Configurable Floating-Point Discrete Hilbert Transform Processor for Accelerating the Calculation of Filter in Katsevich Formula

Authors: Wang Xu, Zhang Yan, Wang Fei, Ding Shunying

Abstract: Katsevich formula is currently a hot topic for cone-beam computed tomography (CBCT). The filter in the formula can be computed by a regular discrete Hilbert transform (DHT). A configurable single precision floating-point (SPFP) DHT processor is proposed for accelerating the calculation of filter in Katsevich formula. The configurable processor is of memory based architecture with one pipelined butterfly processing engine (PE) and supports variable point sizes from 8 to 1024. The DHT processor is controlled by the address generator. According to the point size, the address generator yields one memory address pair per clock cycle to keep the processor accessing memories successively. The DHT is calculated easily via complex multiplications in the frequency domain. Two fast Fourier transforms (FFT) are required in the entire process. The radix-2 FFT algorithm with decimation-in-frequency (DIF) decomposition is utilized in the design to construct an efficiently signal flow graph (SFG) for DHT calculation. Arithmetic calculations, in the last FFT iteration, complex multiplications and the first IFFT iteration are replaced with conjugation and swapping operations, so two iterations are saved in the DHT SFG. Data are loaded and unloaded simultaneously after one frame data calculation is completed. The symmetric property of twiddle factors is utilized to decrease half size of the readonly memory (ROM). Truncation is used in the design to reduce data path width. The proposed DHT processor is written in Verilog HDL, so it is easy for ASIC implementation. Compared with previous works, the performance analysis shows that the proposed DHT processor has minimum clock latency.

Keywords: Discrete Hilbert transform, FFT, floating-point adder, floating-point multiplier, ASIC, VLSI

Title of the Paper: Efficient Algorithms for Noise Estimation in Electrical Power Line Communications

Authors: Abdullah Alwadie

Abstract: Power Line Communication (PLC) has received much attention due to the wide connectivity and availability of power lines. Effective PLC must overcome the harsh and noisy environments inherent in PLC channels. Noise in power lines is modeled as a cyclostationary Gaussian process. In order to achieve reliable communication using power lines, effective measures including error control techniques need to be taken against this particular noise. Low-Density Parity-Check (LDPC) codes have excellent performance in power lines. This paper presents two new iterative algorithms for noise estimation on power lines based on Higher-order statistics and the Maximum-Likelihood (ML) estimation principle, respectively. The algorithm based on Higher-order statistics uses second, fourth, and sixth moments of the received noisy signal to provide a signal-to-noise ratio (SNR) estimate. For the ML estimation algorithm, a derivation of the ML estimate of the amplitude of a Binary Phase-Shift Keying (BPSK) modulated signal is presented. Then, the proposed iterative search algorithm is developed. The proposed algorithms are especially favorable in cases of low SNR values, e.g., the ML estimation algorithm can achieve as large as 7.5 dB and 11.7 dB gains over conventional estimators at an SNR of -5 dB and -10 dB, respectively. Furthermore, since accurate SNR estimation is required for “good” (in terms of bit-error rate (BER)) decoding performance of LDPC codes, the performance of the proposed schemes is compared to some of the previously suggested SNR estimation algorithms. Finally, simulation results show that the proposed estimators perform close-to-optimum at a significantly lower computational complexity.

Keywords: Power Line Communications (PLC), Low-Density Parity-Check (LDPC) Codes, signal-to-noise ratio (SNR) estimation

Title of the Paper: Performance and Capacity analysis of MIMO system at 5 GHz and 60GHz in Indoor Environment

Authors: S. Kirthiga, M. Jayakumar

Abstract: The Millimeter Wave (MMW) band much useful for wireless indoor communications as it offers a large amount of license free spectrum. Blockage by walls and furniture limits the range indoors, the link range for indoors being 10m and outdoors 100m in the case of spatial reuse. The idea of dual-band integration of 5GHz/60GHz conceived by IST-Broadway is considered. The physical link layer throughput achievable in 5GHz would be limited by the available bandwidth while the huge bandwidth available for 60GHz would make it feasible for multi-gigabit link. Spatial multiplexing can offer large capacity gains if the spatial correlation is low. In this work, MIMO channel for 5 GHz and 60 GHz is modeled and the channel capacity is determined. The Triple Saleh Valenzuela model (desktop environment) is chosen as suitable channel model for Millimeter Wave while IEEE 802.11n channel model B (small offices) is chosen for 5GHz. The power delay profile obtained on simulation gives the Rician factor and the RMS delay spread indicating multipath fading and time-dispersive channel. The performance is analysed with respect to bit error rate (BER) for various antenna configurations with transceiver distance of 3m. Consideration of Line –of-Sight (LOS) component shows reduced BER in lower Eb/No range of 1 to 4 dB for 60 GHz compared to 5 GHz radio. This result makes MMW suitable for integration with 5 GHz, whose link is weak for short range communication. The bit error rate (BER) is compared for 2x2, 4x4, and 8x8 for different equalization techniques namely Zero Forcing (ZF), Maximum Likelihood (ML) and Minimum Mean Square Error (MMSE) for the two cases, which in turn had reinforced the fact of better performance of MMW. ML detection offers optimal error performance for 60 GHz. The channel capacity is found to be 2 Gbps for 60GHz and 600 Mbps for 5GHz. The link budget for MMW is also analyzed.

Keywords: Millimeter Wave, Time of Arrival (ToA), Angle of Arrival (AoA), Cluster arrival rate, Ray arrival rate, Spatial correlation

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

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

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

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

Issue 12, Volume 11, December 2012

Title of the Paper: TCP-WLAware: Wireless Loss-Aware TCP for IEEE 802.16 Networks

Authors: K. Sakthi Mala, P. Navaneethan

Abstract: The performance degradation of TCP in wireless and wired-wireless hybrid networks is mostly due to lack of its ability to differentiate the packet losses caused by network congestions from the wireless transmission losses [17]. In IEEE 802.16 networks, wireless loss can occur due to wireless link errors and when the number of bandwidth requests exceeds the maximum. ARQ retransmits the blocks in these two cases repeatedly for a specified number of times till the expiry of block life time and drops the block if the transmission is not successful. Block life time and Request Retries for bandwidth requests are static parameters which are set by the service provider irrespective of the current Round Trip Time, wireless nature and network load. TCP has to retransmit the segment when the retransmission timer expires for such losses if the current window is small. This paper shows that TCP's throughput gets affected by the static parameters and proposes a cross layer feedback approach to enhance TCP-NewReno over IEEE 802.16 networks which can recover from such wireless packet losses and react without entering slow-start. The proposed scheme identifies the MAC block loss and informs the TCP sender about the loss which in turn resends the lost segment to which the block belongs before a time-out. This paper describes the design of the new proposed scheme, TCP-WLAware and presents results from experiments carried out using the NS-2 network simulator. The results from the simulations show that in a wireless congestion free environment, TCP-WLAware is able to apply TCP-NewReno's fast recovery at more number of instances than that of the TCP-NewReno without the enhancement and hence, recover more number of segments.

Keywords: Transmission Control protocol, TCP-NewReno, MAC, ARQ, Bandwidth requests, ARQ_BLOCK_LIFETIME, MAC layer feedback

Title of the Paper: Design of Optimal Waveforms in MIMO Radar Systems Based on the Generalized Approach to Signal Processing

Authors: Vyacheslav Tuzlukov

Abstract: We consider the problem of waveform design for multiple-input multiple-output (MIMO) radar sys-tems employing the generalized detector that is constructed based on the generalized approach to signal proce-ssing in noise. We investigate the case of an extended target and without limiting ourselves to orthogonal wave-forms. Instead, we develop a procedure to design the optimal waveform that maximizes the signal-to-interferen-ce plus-noise ratio (SINR) at the generalized detector output. The optimal waveform requires a knowledge of both target and clutter statistics. We also develop several suboptimal waveforms requiring knowledge of target statistics only, clutter statistics only, or both. Thus, the transmit waveforms are adjusted based on target and clutter statistics. A model for the radar returns that incorporates the transmit waveforms is developed. The tar-get detection problem is formulated for that model. Optimal and suboptimal algorithms are derived for design-ing the transmit waveforms under different assumptions regarding the statistical information available to the ge-neralized detector. The performance of these algorithms is illustrated by computer simulation.

Keywords: Generalized detector, additive white Gaussian noise, detection performance, multiple-input multi-ple-output, signal-to-interference plus-noise ratio (SINR)

Title of the Paper: Adaptive Energy Conserve Routing protocol for Mobile Ad hoc Network

Authors: S. Rajeswari, Y. Venkataramani

Abstract: Protocols are required to optimize network performance based on energy resource due to limited battery power in Mobile Ad hoc NETwork (MANET) nodes. This paper proposes a modified Protocol for MANET to achieve energy efficiency and reliability. The probability for a sleep node is determined by the parameter metric of Packet Delivery Ratio at the destination node. The probability value can be adaptively adjusted by Radio Activated Switch (RAS) which is embedded in each node. This results in less amount of energy consumption and more reliability in Mobile Ad hoc network. User Datagram Protocol and Transport Control Protocol based traffic models are used to analyze the performance of this protocol and NS-2 simulator is used.

Keywords: MANET, Routing Protocol, Delivery Ratio, Energy Consumption, Reliability

Title of the Paper: The Correlation Matrix Model of Capacity Analysis in Unmanned Aerial Vehicle MIMO Channel

Authors: Xijun Gao, Zili Chen, Junwei Lv, Yingsong Li

Abstract: The 3D-GBSBCM (Geometrically Based Single Bounce Cylinder Model) channel model is applied in UAV (Unmanned Aerial Vehicle) MIMO communication system which involves direct, reflection and diffuses components. The concise and precise space-time-frequency correlation functions of the UAV channel model are presented. Methods of channel matrix factorization and channel coefficient normalization are applied to deduce the correlation matrix of UAV-MIMO channel. We also use the assumed parameters of correlation matrix to simulate and analyze the influence of antenna distribution on UAV-MIMO channel capacity when the parameters of channel are certain. The simulation results have good reference and application value in the configuration and collocation of antennas in UAV-MIMO system.

Keywords: UAV channel, GBSBCM, MIMO Channel Correlation Matrix, Channel Capacity


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