PARALLEL ACQUISITION OF PN SEQUENCES IN DS/SS SYSTEMS

We investigate methods for the parallel acquisition of a PN sequence in a baseband direct sequence spread spectrum system. Four different schemes are considered: the optimal estimation scheme, the maximum-likelihood estimation scheme, a hypothesis-testing scheme that searches over all shifts, and a locally optimum detection scheme. Approximate expressions for the probability of error are derived for the first and last of these schemes and compared with the actual error probabilities obtained via Monte Carlo simulation. Monte Carlo simulation is also used to obtain the error probabilities of the other two schemes and the results for all the schemes are compared. Since the obvious methods of implementing a parallel acquisition scheme require large amounts of hardware or excessive computation, we outline a technique that can be used to reduce the amount of computation.