Joint Beamforming, Power and Channel Allocation in Multi-User and Multi-Channel Underlay MIMO Cognitive Radio Networks

In this paper, a joint beamforming, power and channel allocation in a multi-user and multi-channel underlay MIMO cognitive radio networks is considered. The primary users (PU’s) spectrum is reused by the secondary user transmitters (SUTXs) to maximize the spectrum utilization while the intra-user interference is minimized by implementing the beamforming at each secondary user transmitter. After formulating the joint optimization problem as a non-convex, mixed integer non-linear programming problem, a solution is proposed into a two stages. First stage is deriving the beamforming vectors and power allocation under a given channel by converting the original problem into a convex form with an introduced optimal auxiliary variable and semi definite relaxation approach. In the second stage, an explicit searching algorithm i.e., genetic algorithm is proposed to determine suboptimal channel allocation. Simulated result shows that the proposed allocation scheme has a better achievable rate than the existing zero forcing beamforming method.