The ability of the basestation lo separate several users spatially depends on the pair wise cross-correlations between the channel matrices of the users. In this paper we propose an improved null steering downlink MIMO-OFDM system that reduces the intra-user correlations resulting in significant enhancement in system performance. In this system, several bascstation multi-antenna arrays are distributed in a given area. Each array is communicating with the basestnlion via optical fiber links. All signal processing is performed at the bascstation. Multi-antenna users are spatially separated such that in each tone of the OFDM symbol only a certain number of users (out of the total number of users) are selected. The selection is based on an algorithm that reduces the pair-wise intra-user correlations. The channel matrix of each user is assumed correlated (generated based on certain angular spectrum and random angular spread) and Riccan distributed (each array has a random K-factor). Several data symbols can be spatially multiplexed to each user over each OFDM tone with high reliability and with very good total system capacity.
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