The ability of the basestation to 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 basestation multi-antenna arrays are distributed in a given area. Each array is communicating with the basestation via optical fiber links. All signal processing is performed at the basestation. 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 Ricean 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.

Additional Metadata
Keywords Distributed antennas, MIMO, OFDM, SDMA
Conference 5th International Workshop on Multi-Carrier Spread-Spectrum, MC-SS 2005
Citation
Dawod, N.H. (Nadem H.), Hafez, R, & Marsland, I. (2006). Multicarrier SDMA system with reduced intra-user cross-correlations. Presented at the 5th International Workshop on Multi-Carrier Spread-Spectrum, MC-SS 2005.