A Rateless Coding Based Multi-Relay Cooperative Transmission Scheme for Cognitive Radio Networks

Existing spectrum management policies have led to significant over-allocation and under-utilization of the licensed spectrum. To overcome this, cognitive radio is proposed for secondary users to share the licensed spectrum without causing harmful interference to primary users. As such, the transmit power of a secondary user is limited even when it accesses the spectrum hole. Therefore, multihop transmission is a potential method to deliver the data of secondary users over large distance. In such relay systems, the utilization of rateless codes is suitable for the opportunistic spectrum access of cognitive radio. There has been some work in this area. However, the multi-relay cognitive communication with rateless codes has not been carefully investigated. In this paper, we propose a rateless coding based cooperative transmission scheme for cognitive radio networks, where the average end-to-end throughput is analyzed and optimized. We also propose a block search algorithm to find the optimal number of decoding relays with low complexity. Simulation results show that the optimized relay cognitive cooperative transmission can achieve the maximal throughput.