Adaptive Feedback Rate Control in MIMO Broadcast Systems with User Scheduling

In [1], an adaptive scheme was introduced in view of optimizing the overall spectral efficiency of a multiuser MIMO wireless broadcast channel where the channel state information at the transmitting base station (CSIT), to be used for user scheduling and beamforming, is acquired over a limited-rate feedback channel. In this scheme, the feedback rate is no longer constant per scheduling period but rather optimized as a function of the time-dependent channel quality seen at the user side. The present paper further refines this idea and elaborates on some of the associated practical concerns.