Distributed power control with gradual removal in cognitive radio cellular network

In this paper we propose two distributed power control algorithms for cognitive radio cellular network (CogCell). Our objective is to maximize the number of admitted Secondary Users (SUs), while making sure both the Primary User's and SUs' requirements of Quality of Service (QoS) are satisfied with certain constraints. Here the PU's requirement of QoS is described that the Interference Temperature (IT) ascribed to SUs should not exceed a predefined threshold. Similarly, the SU's requirement of QoS is that the Signal to Interference plus Noise Ratio (SINR) at its receiver need to exceed a predetermined threshold. Taking into account the above requirements, it is not always possible that all SUs can be admitted concurrently, instead, one or more of them have to be removed so as to maximize the number of admitted SUs. Thus, we introduce the strategy of gradual removal into CogCell and propose two distributed power control algorithms. Simulation results show that our algorithms have better performances than other algorithms in terms of maximizing the number of admitted SUs.