Performance of multiuser TAS/MRC with 1-bit feedback user scheduling over correlated fading channels

Abstract

We consider a multiuser communication scenario where transmit antenna selection (TAS) is employed at the transmit side and maximal-ratio combining (MRC) is applied at the receive end. In each training period, every user sends a 1-bit feedback (FB) to the transmitter and one user is accordingly scheduled at the transmitter. Subsequently, a single transmit antenna is activated based on a low-rate FB from the scheduled user to the transmitter. We adopt a slow flat fading channel scenario with uncorrelated transmit antennas and correlated receive antennas at each user. First, a general error probability expression applicable to any fading and correlation model with homogeneous users is introduced. Assuming that all the users experience the same exponential correlation structure under Rayleigh and Nakagami-m fading models, we then provide closed-form expressions on bit (symbol) error probability under frequently used modulation schemes. A threshold optimization is performed for the user scheduling process. The inspected low-rate FB scheme is shown to yield an error performance similar to that of a multiuser TAS/MRC technique with analog FB. (C) 2020 Elsevier GmbH. All rights reserved.