Throughput-efficient Relay assisted Hybrid ARQ

Reliable data transmission within wireless communication systems can be obtained via various means, including (i) Hybrid Automatic Repeat reQuest (HARQ) mechanisms which allow retransmission of incorrectly decoded packets; (ii) Additional nodes, called relays, which may also help the transmission by retransmitting these packets. An efficient combination of both techniques is therefore of great interest. This paper investigates a relay assisted HARQ protocol aiming at maximizing the system throughput. The protocol allows the source to transmit a new message during the same time-slot in which the relay is retransmitting a previous message. By using an efficient interference canceler at the destination, the numerical results show significant throughput gain compared to standard approaches.