The effect of different levels of side information on the ergodic capacity in cognitive radio networks

In this paper, we propose several power allocation strategies in cognitive radio network in terms of spectrum sharing. In spectrum sharing, secondary users can simultaneously transmit with the primary users but must strictly control their transmit power to avoid harmful interference to primary users. In this paper, we first maximize the ergodic capacity of a secondary link with full channel side information at the secondary transmitter. Then, different levels of channel side information are separately reduced to discuss the significance of having each level at the secondary transmitter. In most cases, we derived closed-form results for evaluating the maximum capacity over Rayleigh fading channels.