Cooperative Coding Schemes: Design and Performance Evaluation

Cooperation has been recently introduced to mitigate the impairments imposed by fading on a communication channel. A cooperative transmission, in which the destination may overhear all transmission attempts, benefits from incremental redundancy techniques, achieving a higher throughput and reducing the packet delay and the outage probability. This paper presents a theoretical framework to assess the limiting performance of efficient coding techniques in Decode-and-Forward cooperative scenarios. In this paper it is shown that suitable designed codes, such as punctured turbo codes, approach the limiting performance in all the studied scenarios. The paper also addresses the design of punctured turbo code schemes capable of performing close to the presented limiting bound. A novel Genetic Algorithm (GA) is introduced for designing incremental puncturing schemes suited to cooperative transmissions. The algorithm uses a recently proposed tri-dimensional (3D) EXtrinsic Information Transfer (EXIT) chart technique to model the decoding behavior of parallel concatenations of non-systematic periodically punctured convolutional codes. It is shown that the design algorithm allows contriving capacity approaching codes for the source and the relay. The paper further shows that the GA aided designed codes closely approach the theoretical results, outperforming previously proposed systematic incremental and complementary schemes.