Full Duplex with Buffer-Aided Relay

Abstract

In this paper, we study a new full duplex relaying (FDR) network in which the relay has a buffer and works in decode-and-forward (DF) protocol. We investigate the performance of three models in terms of throughput, i.e., Full duplex relay without buffer-aided (conventional FDR), full duplex relay with unlimited buffer, and full duplex relay with limited buffer, respectively, and derive the closed-form expressions of throughput. Throughout this paper, we assume that the transmit rates of the source and the relay are the maximum rate allowed by the quality of the S-R link and the R-D link in all considered models. In the buffer-aided relay scheme, the data, which is transmitted by the source and has not been forwarded by the relay, can be stored in the buffer of the relay if the state of S-R link is better than that of the R-D link at one time slot. Otherwise the relay can forward the data which is transmitted from the source at the current time slot, as well as extract the data from the buffer to retransmit them in order to achieve the maximum allowed rate that is determined by the R-D link as far as possible at later time slots, which is significantly different from previous works owing to the usage of the buffer in FDR. Furthermore, we derive the theoretical expressions of throughput of the three models and verify our analytical results through simulations. Moreover, we study the average queue length of buffer under different buffer sizes. Our results reveal that FDR with buffer-aided can provide better performance in terms of throughput compared with the conventional FDR.