Optimal resource allocation of cognitive radio systems based on spatial multiuser access

This paper investigates the problem of resource allocation in spatial multiuser access cognitive OFDM (orthogonal frequency division multiplexing) systems. The objective is to maximize the cognitive users' weighted rate sum, which is constrained by the licensed users' (LU) interference temperatures. The spatial multiuser access using singular value decomposition (MU-SVD) model is introduced to the cognitive radio (CR) networks application to provide the multi-antenna gain and the spatial multiple access in frequency subchannels of diverse users. In addition, three schemes based on different receiver structures are used to solve the nonlinear and non convex problem. The results show that using spatial decorrelators can formulate the problem into a convex one and provide impressive throughput of the cognitive system.