Opportunistic Interference Cancellation evaluation in cognitive radios under power control strategies

This work considers a cognitive radio (secondary system) that operates under the interference of a WiMAX-like legacy (primary) system. The secondary terminals have knowledge of the codebooks used in the primary system and can apply Opportunistic Interference Cancellation (OIC): if the channel conditions allow, the secondary system can decode and subsequently cancel the interference from the primary system. Contrary to the previous works that utilize the concept of OIC, in this paper we consider practical packet coding, rather than optimal random codebooks in an information-theoretic setting. The key contribution is the mechanism for power control, whose objective is to protect the primary users from a harmful secondary interference. As a dividend, it is seen that in certain regions the proposed power control creates channel conditions that enable the secondary receiver to take advantage of the OIC mechanism. Several power control algorithms have been considered and evaluated in a single and multi-channel scenario. The results clearly indicate the advantage of using power control in conjunction with the OIC concept for achieving spectrally-efficient secondary operation.