Channel allocation in multi-user MIMO wireless communications systems

The use of multi-user multiple input multiple output (MIMO) processing algorithms in wireless communication systems requires new channel allocation algorithms that can intelligently assign users to channels that can best take advantage of the spatial processing available at both transmitter and receiver. The availability of spatial processing at the receiver adds yet another variable to the classic channel allocation problem, making it very difficult to find the optimal solution for a particular set of users at a reasonable computational cost. We propose a two-step heuristic solution. The first step is the computation of a metric that quantifies the spatial compatibility of two users. The second step is to group the users into shared channels based on optimizing the sum of the compatibility metrics over all groups. We also propose a modified version of the algorithm in which the sub-channels (from different multipath components) of a single user are not required to share the same time-domain channel. In simulations, these algorithms conic reasonably close to the optimal solution at a moderate computational cost.