A Dual-Threshold Policy for Opportunistic Spectrum Access in Fading Channels

To improve the effective throughput of the secondary user in hierarchical networks, a dual-threshold policy based on channel quality information is proposed. The proposed policy can utilize the transmission opportunities with good channel quality not only in the sensed idle state but also in the sensed busy state of the channel. With this policy, an optimization problem maximizing the effective throughput of the secondary user with an interference constraint for protecting the primary user is formulated, and the optimal channel quality thresholds are derived. Numerical results validate that the effective throughput of the secondary user can be significantly improved by adopting the proposed policy.