Enhanced interference suppression for spectrum-efficient high data-rate transmissions over wideband CDMA networks

Recently, we developed an efficient multiuser upgrade of the single-user spatio-temporal array-receiver (STAR), referred to as interference subspace rejection (ISR) (Affes, S. et al., IEEE J. Selec. Areas Comm., vol.20, no.2, p.287-302, 2002). The resulting STAR-ISR receiver offers a number of implementation modes covering a large range in performance and complexity for wideband CDMA networks. Here we apply STAR-ISR to high data-rate (HDR) transmissions by extending operation to delay spreads larger than the symbol duration. Low processing gain situations render symbol timing extremely difficult, especially with RAKE-type receivers. For HDR links of 512 Kbps in 5 MHz bandwidth, simulations indicate that the simplest mode of STAR-ISR outperforms the 2D-RAKE-PIC by a factor of 4 to 5 in spectrum efficiency while requiring the same order of complexity. This gain increases by up to a factor of 7.5 in high Doppler.