This letter presents the outage performance analysis for a cognitive relay network (CRN) with imperfect channel knowledge estimations. Under the condition of imperfect channel state information (CSI) estimations of interference links between primary and secondary systems, especially the links from both secondary transmitter and secondary relays to primary users, the exact outage probability is derived over Rayleigh fading channels and is verified through simulations. The simulation results show that: 1) increasing the number of relays is an effective approach to mitigate the outage performance degradation caused by the imperfect CSI; 2) the imperfect CSI of the secondary transmitter-primary user (PU) link has a greater impact on the outage performance than that of the secondary relay-PU link.
['Xing Zhang', 'Jia Xing', 'Zhi Yan', 'Yue Gao', 'Wenbo Wang']
Outage Performance Study of Cognitive Relay Networks with Imperfect Channel Knowledge