A novel hybrid random access policy based on spectrum occupation

In this paper, we propose a novel hybrid random access policy based on spectrum occupation. In this algorithm, cognitive users are provided with three times to access the network by Underlay mode or Interweave mode according to access probability p. As a result, spectrum resources can be fully utilized and decent communication quality is also ensured. Furthermore, a power control model based on outage probability is established, which can guarantee the communication quality of primary and cognitive users. Simulation results show that the proposed policy can make full use of limited spectrum resources to improve system performance.