Throughput maximization in uncooperative spectrum sharing networks

We consider an opportunistic communication system in which a secondary transmitter communicates over the unused time slots of a primary user. In particular, we consider a system in which the primary user is uncooperative and transmits whenever its buffer is nonempty, and the secondary user relies on feedback from its receiver in order to decide when to transmit. The objective of the secondary user is to maximize its own throughput without degrading the throughput of the primary user. We analyze the maximum achievable throughput of the secondary user by formulating the problem as a partially observable Markov decision process. We derive bounds on the optimal solution and find a channel access policy for the secondary user that is near-optimal when the primary user's exogenous arrival rate is low. These results are then used to characterize the set of arrival rates to the primary and secondary users that may be stably supported by the system.