NONCOHERENT HYBRID PARALLEL PN CODE ACQUISITION FOR CDMA MOBILE COMMUNICATIONS

This paper proposes a noncoherent hybrid parallel pseudonoise (PN) cod e acquisition scheme for code-division multiple access (CDMA) mobile c ommunication systems and analyzes the effect of multiple access interf erence (MAI) on the code acquisition performance for Rayleigh and Rici an fading channels, The hybrid acquisition scheme combines parallel se arch with serial search to cover the whole uncertainty region of the i nput code phase, It has a much simpler acquisition hardware structure than the total parallel acquisition and can achieve the mean acquisiti on time slightly inferior to that of the total parallel acquisition in the case of severe MAI; on the other hand, it provides the flexibilit y in the tradeoff between the mean acquisition time and system complex ity if no MAI is considered. The closed-form expressions of the detect ion and false-alarm probabilities and mean acquisition time are derive d, Numerical analysis quantifies the severe performance degradation of code acquisition due to both MAI and channel fading, and demonstrates the dependence of the increase of mean acquisition time (due to MAI) on the number of users in the CDMA system, system design parameters, a nd channel fading statistics.