PERFORMANCE OF MULTIUSER ZERO-FORCING V-BLAST UNDER 1-BIT FEEDBACK FOR USER SCHEDULING

Multiple-input multiple-output (MIMO) system has been acknowledged its capabilities in both achieving high capacity and being reliable over fading channels compared with other wireless communication systems. Many algorithms have been proposed in order to reduce the interference in the received signals of MIMO system. Increasing the data rate and capacity of the system is the main goal of every improvement being made on the transmission schemes of MIMO system. The Vertical Bell Laboratories Layered Space-Time (V-BLAST) system with zero-forcing (ZF) nulling scheme likely has drawn more attention on account of its high spectral efficiency result and comparatively low complexity compared with other transmission approaches. ZF V-BLAST technique achieves full spatial multiplexing gain through parallel and layered transmission without any requirement of channel state information (CSI) being known at the transmitter side. The original V-BLAST concept is based on a single-user scenario developed by Gerard Foschini at Bell Laboratories. In this paper, we study the performance of a downlink multiuser V-BLAST system where a single-user is scheduled in every time slot by the base station. The transmitter is assumed to have two antennas whereas all the users are equipped with r (r ≥ 2) antennas. Each user feeds back a single bit related to the sub-channel gain of its own channel matrix. Then, the transmitter chooses one user and communicates with it. Assuming uncorrelated antennas with Rayleigh fading, we investigate the outage probability of the system. A comparison with the analog feedback is carried out.