Fundamental effective capacity limits of cognitive radio in fading environments with imperfect channel information

In this paper, we analyze the effective capacity gains of opportunistic spectrum-sharing with imperfect channel information. We consider that a secondary user may access the spectrum allocated to a primary user as long as the average interference power, inflicted at the primary´s receiver as an effect of the transmission of the secondary user, remains below predefined power limits. We consider partial channel information of the link between the secondary user transmitter and primary user receiver is available to the secondary user. We derive the optimal power allocation strategy to achieve the maximum effective capacity under Rayleigh fading with imperfect channel information. Finally, we also obtained expressions for the average expenditure-power required to achieve the effective capacity with channel estimation error variance. Numerical results are conducted to corroborate our theoretical results.