G.: A new pre-processing technique to enhance single-user-type DS-CDMA detectors in “blind” space-time rake receivers

Abstract — Proposed herein is a pre-processing technique ap-plicable to maximum-SINR beamformers for “blind ” space-time rake receivers in “single-user”-type DS-CDMA detection. This smart-antennas signal-processing technique enhances the constructive summation of multipaths and the rejection of co-channel interference, both of which decrease the bit-error-rate and lower the error-floor of the cellular uplink’s near-far problem at high SNR. This technique is “blind ” in that it needs neither prior knowledge nor explicit estimation of (1) the channel-faded multipaths ’ arrival angles, relative arrival delays or power profiles, (2) the receiving antenna array’s nominal or actual gain-phase-polarization response, and (3) the co-channel multi-access users ’ signature-spreading codes. Monte Carlo simulations show that the proposed scheme can enhance the output-SINR by 1 − 10 dB. A mathematical analysis shows this proposed pre-processing scheme to always improve the asymptotic output-SINR. A formula is analytically derived to predict this asymptotic output-SINR. This formula lies within 1dB of limited simulation results at an input-SIR above −7dB and a chip-rate space time-sampling, but the formula is less accurate otherwise. Index Terms — Antenna arrays, array signal processing, com-munication system performance, interference suppression, inter-symbol interference, land mobile radio diversity systems, mo-bile communication, pseudo-noise coded communication, spread spectrum communication. I