Analysis of cognitive radio networks with imperfect sensing

Recently, cognitive radio access has received much attention. Spectrum sensing methods are often used for finding free channels to be used by cognitive radios (secondary users). State diagram based approach can be used for analyzing the effects of imperfect spectrum sensing (with false alarms and misdetections). The state diagram consists of two-tuples like (1,2) meaning one primary user and two secondary users present. We note that state dependent transition rates are very important for accurate modeling. This is because for example in state (3,0) (all channels occupied by primary users) collisions happen with increased probability. Our contribution is as follows. Explicit expressions for state dependent transition rates are presented for the case with three channels. However, the approach can be used also for more channels. Primary termination probability is used for evaluating the level of interference to primary users caused by secondary users. Secondary success probability is used to find out how often does a secondary call start and terminate successfully. Simulation and analysis results agree very well.