Hybrid acquisition scheme of PN codes using order statistics-based detection and antenna diversity

Hybrid acquisition of PN codes, using order statistics and multiple antennas, is proposed for direct sequence code-division multiple-access (DS-CDMA) communications. To search for the phase alignment between the local PN code and the incoming PN sequence, the receiver employs a Constant False Alarme Rate (CFAR) detector. The proposed detection scheme utilizes the largest value of the correlation results as a test cell for each antenna element. Next, the adaptive threshold is obtained by using the remaining ordered variables. A non conventional approach is then employed to perform the non-coherent integration of the received multiple-antenna signals. Exact expression for the probability of false alarm is derived, and the performances of the considered system are studied under Rayleigh fading assumptions.