Cognitive Radio Networks With Primary Receiver Assisted Interference Avoidance Protocol

In this paper, a novel opportunistic spectrum access protocol, namely the primary receiver assisted interference avoidance (PRA-IA) protocol, is proposed and analyzed in cognitive radio (CR) networks to simultaneously exploit the underutilized positions of the primary network and avoid transmission collisions among secondary transmitters (STs). Particularly, the proposed PRA-IA protocol is comprised of two processing phases, i.e., the qualification phase and the contention phase. The qualification phase is designed to preselect the set of STs (denoted by eligible STs) which are in the "spatial holes'' of the active primary receivers to guarantee the primary transmissions. The contention phase, on the other hand, aims to improve the performance of secondary transmissions by further resolving the potential collisions among the eligible STs based on the randomly generated backoff timer. With mathematical tools from stochastic geometry, the transmission probability of active STs, the coverage probability, and thereby the spatial throughput of the CR network under the PRA-IA protocol are characterized and analyzed. Furthermore, simulations are provided to verify the accuracy of the derived analytical results and demonstrate the impacts of key network parameters on network performance. From the numerical results, it is shown that the proposed PRA-IA protocol is superior to the PRA protocol on the spatial throughput tradeoff of the primary and secondary networks.