Efficient linear successive allocation for the MIMO broadcast channel

To avoid the complexity of nearly optimum implementations for Dirty Paper Coding (DPC) linear zero-forcing approaches are often preferred. Finding the optimum user allocation, transmit and receive filters for maximizing sum rate in the Multiple-Input Multiple-Output (MIMO) broadcast channel constitutes a non-convex combinatorial optimization problem. Here we present an efficient linear zero-forcing algorithm for this problem, which is derived from maximizing a lower bound for the sum rate. It successively allocates data streams to users and in contrast to state of the art approaches thereby also determines the corresponding receive filters. Compared to existing approaches drastic complexity reductions can be achieved even with slight performance gains.