SINR Balancing Technique and its Comparison to Semidefinite Programming Based QoS Provision for Cognitive Radios

Cognitive radio networks opportunistically operate in frequency bands that have been licensed to other networks. Therefore, communication between unlicensed users should ensure the interference leaked to the licensed users is kept below an acceptable level while achieving the required quality of services. In this paper, we extend SINR balancing technique to serve multiple cognitive users in the downlink while imposing constraints on interference temperature of primary users. We show that when the set interference temperatures is fixed, the proposed SINR balancing technique will always have a unique solution that is identical to semidefinite programming based optimal solution. The advantages and disadvantages of the SINR balancing technique and semidefinite programming based techniques are also discussed.