Spatial multiplexing for outdoor MIMO-OFDM systems with limited feedback costraint

In this paper we propose a spatial multiplexing technique for the downlink of a multiple-input-multiple-output (MIMO) orthogonal-frequency-division-multiplexing (OFDM) system. For outdoor environments with a limited angular spread at the base station, the proposed technique is able to separate the users' streams through a joint spatial processing at both the transmitter and the receiver requiring only a limited feedback from each user. Adaptive transmission is adopted on each stream to set a fixed probability of error. Numerical simulations show that the proposed technique is able to provide significant throughput gains compared to fixed-beams based approaches proposed in the literature.