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.