The Impact of Spectrum Sensing on Primary User in Cognitive Relay Networks

In cognitive networks, with multiple relays available for spectrum sensing and data transmission, the system can get better performance than traditional methods. But with the imperfect spectrum sensing in practice, the secondary user´s (SU´s) transmission may interfere with the primary user (PU) inevitably. Hence, in this paper, we investigate the impact of imperfect spectrum sensing on PU and SU in cognitive relay networks with distributed spectrum sensing (DSS) and cooperative spectrum sensing (CSS). The exact expressions for interference probability of PU are derived under Rayleigh fading channels. Moreover, to evaluate the impact of imperfect spectrum sensing on SU, we put forward the outage probability gap of SU. Finally, the theoretical analysis is validated by Monte-Carlo simulations. The results show that, though the imperfect spectrum badly degrades the system performance, an increase of the number of relays can compensate the loss significantly.