On Joint Power and Admission Control in Underlay Cellular Cognitive Radio Networks

We investigate the problem of designing efficient and low-complexity centralized algorithms for joint power and admission control in a cellular cognitive radio network (CRN) which coexists with a primary radio network (PRN) in a spectrum underlay fashion. We first derive a simple one-to-one relation between the signal-to-interference-plus-noise ratio (SINR) vector and its corresponding power vector of all users of the CRN and PRN, and based on this we propose two new admission metrics. Then, in an infeasible system, where the minimum acceptable target-SINRs for all primary and secondary users are not simultaneously reachable, two centralized algorithms are proposed. These algorithms aim at removing the minimal number of secondary users (based on the proposed admission metrics), subject to the constraint that all primary users are supported with their target-SINRs. In an infeasible system, our proposed algorithms outperform other existing algorithms in terms of complexity and secondary users´ outage ratio. Furthermore, for a feasible system, where all secondary users can be admitted along with all primary users, by using our derived one-to-one relation between SINR and power vector, we solve the problems of maximizing aggregate throughput and max-min quality-of-service (QoS) for secondary users, both subject to the constraint that all primary and secondary users are supported with their minimum target-SINRs.