A Opportunisitic Cooperative Communication Method Based On Space-Time Codes

Cooperative communication is the most effective method to obtain spatial diversity in the filed of wireless communication. The basic idea of cooperative communication is that user not only send it’s own information to the destination, but also send other users’information to the same destination. In this paper, we will study a way of the opportunistic relaying communication which based on space-time coding, this scheme can be take to further enhanced the advantages of cooperative communication. Under this scheme, the user first selects the ’best’ relay node among M surroundings, then the source node and the best relay will combining together with Alamouti space-time codes and transmitting to the destination. The so-called’opportunistic relaying’is owing to the selection of M relay nodes.In this paper we proposed and analysis a distributed method to select the optimal relay, this method needs local instantaneous channel state information instead of topology information. The way also not needs correspondence between relay nodes. The theoretical analysis shows that our proposed scheme has obtained the same diversity degree of other more complex protocols which need M-node space-time codes in the outage probability. And this scheme is superior to the purely space-time coding scheme at the range of SNR(-10,10). It’s simplicity make it can be immediately equipped on the existing wireless devices, it will improve the variability, reliability and efficiency of the future4G wireless system.