PARALLEL ACQUISITION OF PN SEQUENCES IN DS SS SYSTEMS/

We investigate methods for the parallel acquisition of a PN sequence i n a baseband direct sequence spread spectrum system. Four different sc hemes are considered: the optimal estimation scheme, the maximum-likel ihood estimation scheme, a hypothesis-testing scheme that searches ove r all shifts, and a locally optimum detection scheme. Approximate expr essions for the probability of error are derived for the first and las t of these schemes and compared with the actual error probabilities ob tained via Monte Carlo simulation. Monte Carlo simulation is also used to obtain the error probabilities of the other two schemes and the re sults for all the schemes are compared. Since the obvious methods of i mplementing a parallel acquisition scheme require large amounts of har dware or excessive computation, we outline a technique that can be use d to reduce the amount of computation.