Capacity Balancing for Multiuser MIMO Systems

This paper investigates the problem of transceiver design with individual rate constraints for multiuser MIMO systems. We focus on linear processing with two design goals: one is to maximize the minimum rate per user under a total power constraint, and the other is to minimize the total transmit power while maintaining certain rate requirements. The optimization is carried out in an alternating manner in both virtual uplink and downlink channels. Each iteration contains the optimization of uplink power allocation, and uplink and downlink MMSE receive filters. The uplink power control to balance the rates or to achieve the rate requirements is taken by optimizing the product of MSEs, which can be formulated as a geometric programming (GP) problem. Additionally, this alternating optimization approach is suitable for the case with successive interference cancellation (SIC) in the uplink and interference pre-compensation (IPC) in the downlink as well. With a fixed precoding ordering, this provides new sub-optimal solutions to the above problems.