Analytical derivation of finite-data-record performance of Wong-Lok-Lehnert-Zoltowski's DS-CDMA "Blind" space-time receiver

Abstract

Finite-data-record performance and breakdown behaviors are analytically derived for a space-time blind rake-receiver algorithm in a previous proposed by Wong, Lok, Lehnert, and Zoltowski (WLLZ) for uplink direct sequence-code division multiple access (DS-CDMA) cellular wireless communications using only single-user-type conventional detectors with either short or long spreading sequences. WLLZ is significant because it needs no prior knowledge nor explicit estimation of 1) the fading channel's multipaths' arrival angles/delays/amplitudes/complex-phases, 2) the receiver's nominal or actual (i.e., calibrated) antenna-array manifold, and 3) the other CDMA users' signature spreading-codes. This analysis a) reveals how the multiuser access cellular system's various parameters influence WLLZs blind beamformer's output SINR. These herein-derived quantitative relationships are explicit, closed-form, and accurate to within 1/2-2 dB for the examined scenarios if WLLZ does not break down . This analysis also b) explains WLLZ's breakdown, which can occur for channels with large delay-spreads, due to a matrix rank deficiency, explicitly in closed-form and in terms of the fading-channel's delay spread and temporal variability. It also c) proposes a simple algorithmic modification to WLLZ to avert its breakdown.