Power Minimization and QoS Feasibility Region in the Multiuser MIMO Broadcast Channel with Imperfect CSI

The aim of this work is to jointly achieve individual rate requirements and minimum total transmit power in a Multi User Multiple Input Multiple Output (MU-MIMO) Broadcast Channel (BC). Data streams are transmitted from a multi-antenna base station to several independent and non-cooperative multi-antenna users. Perfect Channel-State-Information (CSI) is known at the receivers and it is fed back to the transmitter, where partial CSI is used for the design of linear transmit filters. Employing a duality between Multiple Access Channel (MAC) and BC w.r.t. the average Mean Square Error (MSE) and identifying standard interference functions, we propose an algorithmic joint solution for the transmit filter design and the power allocation. Additionally, we describe the feasibility region in the average MMSE domain. This result allows for checking the convergence of the algorithm for given Quality of Service (QoS) constraints.