Scheduling of multi-antenna broadcast systems with heterogeneous users

We consider a two transmit antenna broadcast system with heterogeneous users, and tackle the problem of maximizing a weighted sum rate. We establish a novel upper bound for the weighted sum capacity, which we then use to show that the maximum expected weighted sum rate can be asymptotically achieved by transmitting to a suitably selected subset of at most 2C users, where C denotes the number of distinct user classes.Numerical experiments indicate that the asymptotic results are remarkably accurate and that the proposed schemes operate close to absolute performance bounds, even for a moderate number of users