Link adaptation schemes for finite-buffer aided relaying systems with asymmetric channels

This paper considers a three-node buffer-aided relaying system which consists of a source node (SN), a destination node (DN) and a relay node (RN) with a finite-size buffer. With the help of the buffer, the RN is able to store the decoded message before retransmitting it to the DN. We consider a fixed rate transmission and propose two link adaptation (LA) schemes, namely the probability based LA (PB-LA) scheme and the state based LA (SB-LA) scheme, to minimize the outage probability of the system. The optimal LA criteria are investigated for these two proposed schemes. It is shown that compared with the traditional max-link transmission scheme, the two proposed schemes can achieve better outage performance. Furthermore, the outage probability of the proposed SB-LA scheme can almost approach the lower bound. Numerical results are provided to verify the ideas proposed in this work.