Adaptive Cooperative Transmission Scheme Based on Distributed Relay Selection

Cooperative diversity could form the virtual multiple antenna array and enlarge the network capacity enormously by sharing the different network users' antennas.However,only adoption of cooperative diversity can not combat the dynamic variation of network topology and the multipath fading of wireless transmission,for which we should employ both the cooperative diversity and the corresponding adaptive transmission strategy.Accordingly,the optimal criteria to select the cooperative relay among all the candidates is proposed in this paper,based on which a distributed relay selection protocol is presented.An adaptive cooperative transmission scheme is further proposed in accordance with the channle quality between cooperative relay and source node.Besides,closed-form expressions of BER(bit error ratio) for the proposed adaptive cooperation scheme is presented over Rayleigh fading channels.Then,numerical simulations are conducted to compare our scheme with the traditional cooperative diversity,showing the merits of the proposed adaptive cooperative diversity in terms of BER.