Performance analysis of cooperative diversity at PHY layer in wireless sensor networks

In this paper, the performance of cooperative diversity for reach-back problem in wireless sensor networks is studied, in which network synchronization or orthogonal channels are not necessary. The bit error rate and diversity order of destination are respectively developed for two typical channels, considering the error propagation appeared in the decode-and-forward procedure. It's shown by the analysis that the increase of the node's number will improve the performance in destination if relays are at normal working point. To increase hop number is more effective for the scenario of AWGN channel among relays, while it is better to increase the number of branches when the channels among relays are Rayleigh fading. Cooperation diversity outperforms the direct transmission or the traditional spatio diversity if the relays are located in a certain region. Error propagation will reduce the diversity order of destination to 1, whereas almost has no influence on the diversity gain at the medium and low signal-noise-rate.