Buffer size and link quality based cooperative relay selection in wireless networks

Relay selection in cooperative communication is an efficient approach to mitigate the spectral efficiency loss faced in cooperative diversity systems. In this paper, we propose a relay selection scheme for buffer-aided cooperative systems. It simultaneously considers the instantaneous link quality and the buffer status of relay nodes in the relay selection decision. The normalized and weighted sum of these parameters results into the overall score of each link, and a link with maximum score is selected. First, the concept of equivalent outage of a link corresponding to a buffer-aided relay is explained, and then Markov chain (MC) modeling is used for the evaluation of states of buffer. We provide the specific examples with fixed values of number of relays and buffer size. The system achieves the full diversity gain of 2K for the smaller buffer sizes.