Near-far resistant single-user channel identification by interference subspace rejection in wideband CDMA

The single-user CDMA spatio-temporal array receiver (STAR-SU) can be extended to a multiuser version (STAR-MU) by incorporating interference subspace rejection (ISR) using spatio-temporal null-beamforming. We can exploit the data-projection step implemented there to enhance the channel identification for STAR-SU so that it is significantly more robust to near-far power variations than the previous formulation. Our approach effectively decomposes the MU subspace tracking into much simpler single-user 1D subspace tracking operations. Simulations on the downlink reveal that the performance of the new STAR-SU is close to the single-user bound even for near-far ratios as high as 18 dB.