Reduced rank beamforming methods for SDMA/OFDM communications

Spatial division multiple access (SDMA) allows reuse of frequency by multiple users to increase capacity. When combined with OFDM modulation, SDMA can operate on per-carrier basis. For instance, in an OFDM/SDMA system, MMSE receiver can be applied to each carrier to suppress cochannel interference (CCI). An alternative implementation of MMSE receiver includes reduced-rank processing which is shown to be effective to reduce complexity (AM, Haimovich, et al., 2000). In this paper, we study the reduced rank OFDM/SDMA receiver based on Krylov subspace approach. Simulations are used to show the effectiveness of the proposed reduced rank receiver in cellular OFDM/SDMA communications while reducing the implementation complexity.