Joint Design and Separation Principle for Opportunistic Spectrum Access

This paper develops optimal strategy for opportunistic spectrum access (OSA) by integrating the design of spectrum sensor at the physical layer with that of spectrum sensing and access policies at the medium access control (MAC) layer. The design objective is to maximize the throughput of secondary users while limiting their probability of colliding with primary users. By exploiting the rich structures of the problem, we establish a separation principle: the design of spectrum sensor and access policy can be decoupled from that of sensing policy without losing optimality. This separation principle enables us to obtain closed- form optimal sensor operating characteristic and access policy, leading to significant complexity reduction. It also allows us to study the inherent interaction between spectrum sensor and access policy and the tradeoff between false alarm and miss detection in opportunity identification.