Optimal transmission strategy for cognitive radio networks with partial channel state information

Abstract

In this paper, we consider a spectrum sharing based cognitive radio (CR) network where the secondary user (SU) coexists with the primary user (PU) as long as the interference power received by the PU is less than a acceptable threshold. Suppose that the SU's transmitter and receiver are equipped with multiple antennas and the PU's receiver are equipped with single receive antenna. We assume that the SU's channel state information (CSI) is known at the SU transmitter perfectly, however, due to less cooperation between the SU and the PU, only partial CSI between SU and PU is available at the SU transmitter. We seek to determine the optimal transmit signal covariance to maximize the transmission rate of the SU where the covariance is subject to the average interference power constraint of the PU as well as the transmit power constraint of the SU transmitter. Two iterative algorithms are proposed to solve these problems, and it is shown that the algorithms can converge to the optimal solution. Simulation results are provided to show the effectiveness of the algorithms.