SDMA, Multiuser Diversity, and BF Using Array Antenna in OFDMA System

A scheme which supports SDMA and enhances system performance using gains from multiuser diversity as well as beamforming is proposed. The proposed scheme is a kind of closed-loop multiuser MIMO applications applicable to both in the uplink and downlink with a small amount of overhead to construct downlink preamble which is inevitable for the mobile station to determine feedback information which shall be reported to base station. Based on the feedback from multiple users, BS exploits benefits from multiuser diversity by scheduling and implements SDMA using directional beamforming with half-wavelength spaced array antenna. Performance enhancement is verified by link level simulation and applicable scenarios are suggested.