Coded Cooperative Communications

University essay from Blekinge Tekniska Högskola/Avdelningen för signalbehandling

Abstract: Wireless communication has been evolving and growing rapidly during the last few years. In order to meet the demand of this growth researchers as well as industry have been working for new techniques and new standardizations. Usually wireless communications performance is badly affected by channel fading. Diversity technique is used to reduce the impact of fading on wireless channel by conveying data over multiple independent fading channel paths and combine them at the receiver. Cooperative diversity is novel transmission technique where multiple terminals use their resources in cooperative manner to form a virtual array that realizes spatial diversity gain in a distributed fashion. Cooperative system can obtain reliable communications, capacity gain and energy saving by mutual relaying among users of wireless network. In this thesis work we examine the performance of a cooperative system and its ability to realize the advantages and the ideas behind its invention. We model a simple decode and forward repetition-based cooperative system consisting of three nodes representing source, destination and relay, which communicate cooperatively between the source and the destination. To evaluate the performance of cooperative system we measure the probability of error of cooperative system using computer simulation. Our results show that a better performance of a communication system could be achieved by allowing wireless network partners to communicate cooperatively. In the last part of the thesis, and for more investigation of the new technique we built a test bed to implement cooperative system model so as to measure its performance practically. Click router and computers with wireless cards are used for the implementation. Click programming language is used to configure the network nodes.

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