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Energy efficiency and network lifetime are key factors in characterizing wireless sensor networks due to the limited energy of nodes. In this paper we present two approaches to routing in wireless sensor networks that utilize the ideas of node cooperation and information exchange to achieve cognition across multiple network layers. In the first proposal, nodes exchange information about their statistical...
This article studies the outage capacity of bidirectional relaying using Decode and Forward (DF) in cognitive relay networks. We consider a communication system where two sources attempt to exchange their messages through a set of cognitive relay nodes. Only relays with successful decoding and spectrum acquisition are allowed to participate in the broadcast phase (BC). We consider two schemes for...
Accurate and efficient localization of tags are of utmost importance for numerous existing and forthcoming RFID applications. In this paper, we introduce two novel methods for three dimensional localization of the passive RFID tags. In the first approach, namely Adaptive Power Multilateration (APM), using four RFID readers, distance estimations parameters are processed based on the minimal interrogation...
This paper presents a methodology, a theoretical framework, and some novel ideas on performance modeling and evaluation of application-specific cognitive wireless sensor networks applied to environmental protection. Cross-layer optimizations integrating the use of adaptive sleep, adaptive modulation and energy-aware higher layer processing and protocols are assumed. Routing and application layer processing...
This paper presents the design procedure and implementation results of a 16 quadrature amplitude modulation (16-QAM) look up table (LUT) predistortion technique for satellite communications using Altera DSP board. The implementation uses Matlab/Simulink, Altera DSP builder and Altera Stratix DSP EP1S80 development board. The design is first implemented in Matlab/Simulink environment. It is then converted...
We propose a neural network pilot symbol-aided (NN-PSA) receiver for nonlinear satellite mobile channels. The NN-PSA receiver is composed of a two-layer memory-less neural network (NN) nonlinear identifier and a pilot symbol-aided (PSA) fading estimator. In comparison with traditional techniques, the main advantage of this receiver is that it is able to identify and track both the nonlinearity and...
Multiple-input multiple-output (MIMO) systems have gained an enormous amount of attention as one of the most promising research areas of wireless communication. However, while MIMO systems have been extensively explored over the past decade, few schemes acknowledge the nonlinearity caused by the use of high power amplifiers (HPAs) in the communication chain. When HPAs operate near their saturation...
This paper examines the impact of antenna selection on the performance of multiple input-multiple output (MIMO) systems over nonlinear communication channels. Analytical expressions are derived for evaluating the PWEP performance of space-time trellis codes over nonlinear MIMO channel, case of Rayleigh fading, when antenna selection is employed at the receiver side. Performance degradation due to...
Wireless sensor networks (WSNs) are applied in several multi-disciplinary areas, offering powerful combination of distributed computing, sensing, and communication. At the same time, they pose several challenges, mainly because of their random deployment and non-renewable energy resources. This paper gives an overview of the applications of WSNs and discusses their major challenges with a special...
The paper proposes a neural network (NN) approach for modeling and identification of a class of nonlinear multiple-input multiple-output (MIMO) channels. The unknown MIMO system is composed of a set of single-input memoryless nonlinearities followed by a linear combiner. The proposed NN model consists of a set of single-input memoryless NN blocks followed by an adaptive linear combiner. The performance...
This paper proposes a simple joint adaptive modulation and predistortion scheme over nonlinear time-varying channels equipped with High Power Amplifiers (HPAs). The paper includes the probability of Bit Error Rate (BER) analysis of MQAM transmission over nonlinear channels, which is the key factor in designing adaptive modulation. The paper includes performance comparison of adaptive modulation over...
This paper investigates the performance of MIMO subset antenna selection systems over nonlinear fading channels. Pairwise error probability (PWEP) performance of 16-states space-time codes with antenna selections are derived over nonlinear MIMO channels. Performance degradations due to non-linear amplifications of the transmitted coded symbols are then evaluated for the reduced-complexity systems...
This paper proposes a simple adaptive modulation scheme over nonlinear time-varying channels equipped with high power amplifiers (HPAs). The paper includes the probability of bit error rate (BER) analysis of M-QAM transmission over nonlinear channels, which is the key factor in designing adaptive modulation. The paper includes performance comparison of adaptive modulation over linear and nonlinear...
Neural network (NN) based channel estimation method has been proposed for identifying the parameters of a nonlinear time varying satellite channel. A multipath time-varying Ricean-fading channel has been considered in the analysis for a down link scenario. To study the flexibility and performance of the proposed method, the channel in question has been varied over a reasonable range of Doppler frequencies,...
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