Effective capacity of delay quality-of-service guarantees with imperfect channel information in spectrum-sharing environment

This paper considers a spectrum-sharing cognitive network in which a secondary user shares spectrum with an existing primary user as long as the interference caused by the secondary user to the primary user is below permissible levels. We investigate the delay quality-of-service (QoS) guaranteed capacity gains with imperfect channel state information (CSI) between the secondary transmitter and the primary receiver in Rayleigh fading environments. In particular, we quantify the relations between the effective capacity of secondary user and the interference on the primary user. The impacts of channel estimation error on the performance of the secondary user are studied. Our results indicate channel estimation errors, especially in the smaller value range, lead to considerably degradation of capacity gains for the looser delay QoS requirements. Numerical simulations are conducted to corroborate our theoretical analysis.