Scheduling Algorithms for MU-MIMO with Partial Current CSIT and Full Delayed CSIT

Recently, a novel class of high-performance multi-round MU- MIMO schemes were developed by Yang et al. [1] for the practically attractive scenario in which the transmitter has available partial channel state information (CSI) regarding the current state of the channel, but also full delayed CSI. We study methods for combining user scheduling with these multi-round transmission schemes, in order to realize some of their multiplexing gains in the form of high-rates in the SNR regime of practical interest. In these multi-round schemes several differently encoded signals are transmitted to each user over many time-dispersed slots. The challenge in designing schedulers is that certain signals intended for a given user are transmitted in different forms and combinations with other-user signals over multiple slots, occurring at distinctly different times with distinctly different channels. We develop a simple and novel scheduling framework based on appropriate resource division between transmission rounds and round-specific scheduling criteria. Simulation-based performance analysis of the proposed scheduling algorithms, operated on the 2-user transmission scheme of Yang et al. [1] and a 3-user extension suggest that these schemes can harvest significant scheduling benefits in some scenarios.