Acquisition of direct sequence spread spectrum signals in frequency selective Rayleigh and Ricean channels

Wideband wireless communication systems based on the code division multiple access (CDMA) technique are increasingly being used for data communication. Initial acquisition (synchronization) in such systems employing random (long) spreading codes has been studied, and the corresponding optimal receiver has been designed. We investigate here initial acquisition when the system employs deterministic (short) spreading codes. We derive the optimum receiver that accounts for the deterministic nature of the spreading codes. This receiver lends itself to a simple implementation, unlike the optimal receiver for the long spreading codes, which involves Bessel functions. Finally, we show that using our optimum receiver with lower processing gain (and hence with reduced complexity), we can obtain performance comparable to that of a system with higher processing gain.