Asynchronous down-link cooperative communication scheme in Rayleigh fading wireless environment
Ahmed Desouky, Ahmed El‐Mahdy · 2016
In this paper, a down-link cooperative communication scheme is proposed using full-rate Quasi-Orthogonal Space-time Block Codes (QOSTBC), employing asynchronous mobile Decode and Forward (DF) relays in a Rayleigh fading wireless environment. The channel used is a partially-coherent relay channel (PCRC), where the first hop is non-coherent and the second is coherent. Base station broadcasts using four transmitting antennas, towards all relay nodes in range over the first hop. Each intermediate relay uses Minimum Decoding Complexity (MDC) decoder achieving linear complexity. A relay selection technique is applied, electing the best performing intermediate nodes based on the channel response and path loss due to location relative to the destination node. A power allocation technique is adopted, which ranks based on the chosen relays performance. Relays transmit over four pre-defined time slots per frame. The destination node uses a Maximum-Likelihood (ML) decoder.