Spatial throughput characterization in cognitive radio networks with primary receiver assisted carrier sensing based opportunistic spectrum access

This paper studies the opportunistic spectrum access (OSA) of secondary users in large-scale overlay cognitive radio (CR) networks. Particularly, a two-phase carrier sensing based protocol, namely the primary receiver assisted carrier sensing (PRA-CS) protocol, is investigated. Under the PRA-CS protocol, a secondary transmitter (ST) is allowed to transmit only if it satisfies the interference constraint at all the active primary receivers (PRs) and has the minimum back-off timer among its secondary contenders. It is worth noting that under the PRA-CS protocol, due to the fact that the activation of STs relies on the spatial realizations of both the primary and secondary networks, even the first order moment measure (average density) of the point process formed by the active STs can not be exactly characterized. To tackle this new difficulty, approximations are made on the conditional distributions of the eligible STs as well as the active STs given a typical primary/secondary receiver (PR/SR) activated at the origin. Based on such approximations, the coverage (transmission non-outage) performance of the primary/secondary network under the proposed PRA-CS protocol is characterized. Simulations are provided to validate our analysis.