Performance of Cognitive Radio CDMA networks with secondary user removal in spectrum underlay

In this paper, we propose a novel algorithm to remove secondary users (SUs) in a Cognitive Radio (CR) CDMA network to maintain a predefined interference threshold at BS. Specifically, we develop a simulation test bed for analyzing performances of a CR user and a primary user (PU) in a single cell. CR users or SUs are assumed to form pair wise link in an infrastructure less ad hoc network that coexists with a primary radio network (PRN). A SU link is removed from the list of SU links on the basis of its interference at BS. Removal of SU links would improve performance of PU and existing SUs. Further, we evaluate the performance of PRN and CRN in terms of average power increase of PU, achievable data rate of SU and number of SUs removed.