User Recognition and Signature Code Acquisition for CDMA Receivers

摘要

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; this motivates the study o f the signal recognition and code acquisition (SR/CA) scheme we describe in this paper. Specifically,starting form elementary estimation theory criteria, we work out a non-coherent parallel SR/CA algorithm that is easily suited to a low-complexity full-digital implementation, possibly 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 one-bit signal quantization, to allow optimization of the design parameters as a function of the characteristics of the received signal.