Cooperative Multi-Cell Block Diagonalization With Per-Base-Station Power Constraints
Block Diagonalization (BD) is a practical linear pre-coding technique that eliminates the inter-user interference in downlink multiuser Multiple-Input Multiple-Output (MIMO) systems. In this paper, the authors apply BD to the downlink transmission in a cooperative multi-cell MIMO system, where the signals from different Base Stations (BSs) to all the Mobile Stations (MSs) are jointly designed with the perfect knowledge of the downlink channels and transmit messages. Specifically, they study the optimal BD pre-coder design to maximize the weighted sum-rate of all the MSs subject to a set of per-BS power constraints. This design problem is formulated in an auxiliary MIMO Broadcast Channel (BC) with a set of transmit power constraints corresponding to those for individual BSs in the multi-cell system.