Reduced-Rank MMSE Detection in Space-Time Coded Space-Division Multiple-Access Systems

A multiple-input multiple-output (MIMO) space-division multiple-access (SDMA) system is presented and investigated, when the space-time block coded (STBC) user signals are transmitted over Rayleigh fading channels. In the proposed SDMA system each mobile uses two transmit antennas, while the base-station (BS) receiver employs multiple receive antenna arrays and each receive antenna array consists of several array elements. The MIMO SDMA signals at the BS are detected with the aid of various reduced-rank MMSE schemes. Specifically, three classes of reduced-rank MMSE techniques are investigated in conjunction with the proposed SDMA system. The three classes of reduced-rank MMSE algorithms are derived, respectively, based on the principles of principal components (PC), cross-spectral metric (CSM) and Taylor polynomial approximation (TPA). Our study and simulation results show that the reduced-rank MMSE detection is capable of achieving a satisfactory trade-off between the affordable detection complexity and the achievable detection BER performance