Signal recognition and signature code acquisition in CDMA mobile packet communications

Abstract

Fast and reliable signal sense and signature code synchronization for direct-sequence spread-spectrum (DS-SS) signals are key issues in the design of the receiver for modern packet code-division multiple-access (CDMA) radio networks for mobile communications; this motivates the study of the signal recognition and code-acquisition (SR/CA) scheme we describe in this paper. Specifically, starting from elementary estimation and detection theory criteria, we work out a noncoherent parallel SR/CA algorithm that is suited to a full-digital implementation in a single application-specific integrated circuit (ASIC). The results of a theoretical analysis of such a scheme, encompassing additive white Gaussian noise (AWGN) and multiple-access interference (MAI), are integrated and validated by an overall time-domain system simulation. We also evaluate through a simplified approach the impact of some degradation factors on the overall circuit performance, namely, sampling epoch and carrier frequency offset and 1-b signal quantization, to allow optimization of the design parameters as a function of the characteristics of the received signal.