Virtual Receive Antennas for Spatial Multiplexing System

Spatial multiplexing with layered space-time receiver is one of the multiple input multiple output (MIMO) schemes that can achieve the linearly increasing capacity. However, layered space-time processing requires the number of receive antennas to be the same or larger than the number of transmit antennas. It is difficult to design a small sized mobile unit with such number of antennas, and hinders the broad dissemination of this promising technology. The authors investigate this problem and present the novel concept of virtual receive antennas for spatial multiplexing system. Each substream is transmitted with a specific timing offset, and the received matched filter output signal is oversampled. The oversampled signals have certain properties such that they can be considered as signals from correlated antennas. Hence, virtual receive antennas are created and the number of physical receive antennas can be reduced. Simulation results are presented to demonstrate the system performance.