Adaptive algorithm and relay selection for decode-and-forward cooperative multiple-antenna terminals

Cooperative diversity has been identified as an enabling method for high-rate data transmissions over wireless channels and attracted great attention recently. In this paper, an adaptive DF cooperative diversity algorithm and an improved relay selection strategy are presented on the basis of analysis of the BER performance of decode-and-forward (DF) cooperative diversity with multiple-antenna terminals. The adaptive algorithm adopts non-cooperation or cooperation approach according to instantaneous channel state information for each frame to avoid unnecessary cooperation and improve the BER performance further. Two thresholds and a simple energy gain estimation method are used in the improved relay selection strategy thus the computational complexity is reduced greatly. Theory analysis and computer simulation both prove that the adaptive algorithm and relay selection strategy can be simply adopted into cooperative diversity system and improve the BER performance further and achieve high energy gain.