Cooperative ARQ in full duplex cognitive radio networks

In this paper, we propose a cooperative automatic repeat request (ARQ) scheme for cognitive radio networks with full duplex (FD) capability. Cognitive system takes advantage of opportunities arising during primary's ARQ retransmission rounds for transmission of data whilst cooperating with primary network at the same time. This requires self-interference cancellation as well as known interference cancellation capabilities of destination nodes in the secondary network which are achievable with recent advances in FD technology. It is shown that the proposed protocol will achieve non-trivial throughput gain for the secondary network during primary's ARQ rounds without any degradation of the primary's performance. The validity of this method has been investigated in terms of data link layer Packet Error Rate (PER) as an important and practical figure of merit. Performance of the proposed protocol is analyzed mathematically and its effectiveness is verified via simulations.