New pre-processing technique to enhance single-user-type DS-CDMA detectors in "blind" space-time rake receivers

• Published in: IEEE transactions on wireless communications 2006-10, Vol.5 (10), p.2932-2944
• Main Authors: Wong, K.T., Tichavsky, P., Cheung, S.K., Liao, G.
• Format: Article
• Language: English
• Subjects: Antenna arrays; Antennas; Applied sciences; Asymptotic properties; Blinds; Computer simulation; Delay estimation; Detectors; Equipments and installations; Exact sciences and technology; Fading; Interchannel interference; Mathematical analysis; Mobile radiocommunication systems; Monte Carlo methods; Multiaccess communication; Multipath channels; Noise levels; Radiocommunications; Rakes; Receivers; Receiving antennas; Signal detection; Studies; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments)
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2006.04741

Proposed herein is a pre-processing technique applicable 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 1 dB of limited simulation results at an input-SIR above -7 dB and a chip-rate space time-sampling, but the formula is less accurate otherwise