Abstract
In this thesis, we present a spectral-efficient automatic repeat request (SEARQ) scheme with relay selection for two-way amplify-and-forward relay systems, where multiple single-antenna relays are considered but only one relay is selected to join in cooperation with two terminals. The proposed SEARQ scheme exploits two-way retransmission for failure of reception at both terminals, and adopts two-way partial retransmission for failure of reception at only one terminal in a way that the corresponding source performs retransmission and the other source continues to transmit new data. Both of the outage probability and effective throughput for the proposed SEARQ scheme are derived in closed form based on second-order channel statistics. To further improve the effective throughput performance, we develop a single-relay selection method for combination with the proposed SEARQ scheme. We also derive an optimal maximum-retransmission round for the proposed SEARQ scheme with the optimally selected relay by solving a maximization problem of the effective throughput. Simulation results are given to verify the theoretical analyses as well as to demonstrate the effectiveness of the proposed approach.