Approaching large-system limits faster in multiuser MIMO with adaptive channel feedback adjustments

In this paper, we focus on the well-known drawback of per user unitary beamforming rate control (PU²RC) that sum throughput severely degrades with a small number of users due to the mismatch between the actual link quality and channel feedback of users. We propose an adaptive channel feedback adjustment (ACFA) method which estimates the actual link quality by adaptively adjusting user feedback according to the number of scheduled users. Numerical results show that the proposed ACFA considerably increases sum throughput of PU²RC especially when the number of users is small.