Power allocation for multi-user downlink MIMO transmissions

We consider the problem of robust joint transmitter and receiver power allocation for downlink multiple input multiple output (MIMO) transmissions. The channel model is assumed to be Rayleigh frequency flat fading. The objective of power allocation is to minimize the total mean square error under total transmit power constraint. Under robustness issue, we consider joint power allocation with imperfect channel state information (CSI), where the CSI error is assumed to have Gaussian distribution. We show that this problem is formulated as a convex optimization problem. Numerical results indicate the BER performance improvement obtained by considering the robustness into account in the joint power allocation process.