A rollout-based joint spectrum sensing and access policy for cognitive radio networks with hardware limitations

The practical hardware limitations bring technical challenges to cognitive radio, e.g. limited capability of spectrum sensing and certain frequency range of spectrum access. In this paper, we propose a rollout-based joint spectrum sensing and access policy incorporating the hardware limitations of both sensing capability and spectrum aggregation, in which the optimal policy is shown to be PSPACE-hard. Two heuristic policies are proposed to serve as base policies, based on which the developed rollout-based policy approximates the value function and determines the appropriate spectrum sensing and access actions. We establish mathematically that the rollout-based policy achieves better performance than the base policy. We also demonstrate that the low-complexity rollout-based policy leads to only slight performance loss compared with the optimal policy.