Analysis of different precoding/decoding strategies for multiuser beamforming

In this paper we study multiuser beamforming optimization for the uplink and the downlink of a cellular wireless system. This problem can be approached under different side conditions, like power constraints (total vs. individual), signal processing complexity (linear vs. non-linear successive precoding/decoding) and with different performance criteria (e.g. SINR, sum rate, effective bandwidth). We analyze and compare different transmission strategies and show that even though they are closely related, they may largely differ in their analytical structure. In particular, we investigate whether or not the given problems are convex, which is important for the design of efficient algorithms.