Return link 2-D code acquisition for DS-CDMA in a high capacity multi-user system

摘要

Acquisition of the code timing in a direct-sequence code-division multiple-access system with antenna arrays must take place before signal detection and decoding is possible. Code acquisition under severe multiple access interference conditions with time varying codes makes the task even more difficult and has been shown to limit the capacity of the system. This paper details a powerful code acquisition technique for the uplink of direct-sequence code-division multiple-access systems under high loaded situations, where the number of users is much larger than the spreading factor. The method discussed utilises soft data from the multi-user detector to reduce the interference received by the acquisition unit. Numerical and analytical performance compared in terms of the probability of missed detection and the probability of false alarm is shown.