Joint Linear Precoding and Power Allocation for MU-MIMO CR Systems with Imperfect CSI
Wei Wang, Yan Hui Lu, Duan Li, Shou Yi Yang · Applied Mechanics and Materials · 2014
This paper proposes a joint linear precoding and power allocation design scheme for multiuser multiple-input multiple-out (MU-MIMO) cognitive radio (CR) systems, where secondary users share the same spectrum with one primary user. The interference power constraint required by the primary user and the multiuser interference generated by secondary users impose negative influence on each secondary user. As a result, it is difficult for secondary users to achieve the ideal information rate. In order to solve the above problem, we respectively adopt Channel Inversion (CI) and Block Diagonalization (BD) for precoding matrices which are set at the transmitter of each secondary user, and then make the system reach a steady state by power allocation. In fact, perfect CSI cannot exist in wireless systems. Therefore, it’s necessary to consider imperfect CSI. Simulation results show BD gains a higher rate for secondary users, but imperfect CSI causes less loss to CI.