Cooperative coding based retransmission protocol for cognitive radio networks by exploiting hybrid ARQ

This paper deals with the retransmission protocol design for cognitive radio networks by exploiting the primary hybrid ARQ. In contrast with previous work that focuses on cancellation based retransmissions, we propose a novel cooperative coding based retransmission protocol for cognitive radio networks. The design objective is to improve the throughput of the primary user and create the transmission opportunity for the secondary user. By exploiting the primary retransmission appropriately, the knowledge on primary packet which is required by the cooperative coded retransmission can be obtained without any non-causal assumption. Performances on the proposed protocol are analyzed mathematically, and verified by numerical results.