Optimal spectrum management in multiuser interference channels

In this paper, we investigate the optimal spectrum management problem in multiuser frequency selective interference channels. First, a simple pairwise interference coupling condition under which FDMA can achieve all Pareto optimal points of the rate region is discovered. Not only is this condition sufficient, we show that it is also necessary for FDMA to be always optimal at least in symmetric channels. For the general cases where this condition is not necessarily satisfied, we first explicitly obtain the optimal solution as the optimal combination of flat FDMA and flat frequency sharing for the sum-rate maximization problem in two user symmetric flat channels, and then show that the general n-user weighted sum-rate maximization in non-symmetric frequency selective channels can be formulated into primal domain convex optimizations.