The problem of estimating the propagation delay of a new user in a DS/CDMA system in the presence of multiple access interference is considere. MAI resistant acquisition schemes are developed for a general CDMA system without the ocnstraint that the spreadingsequences of the users repeat every symbol period. it is assumed that the spreading sequem=nces and delays of the interfering users are known. however, knowledge of their amplitudes is not assumed, and their unreliable code-symbol estimates are not used. under this scenario, the optimum maximum-likelihood scheme is derived. An approximation to the ML scheme, the AML scheme, is alos presented for the situation where the chip timing is known a priori. The performance of the AML scheme is analyzed suing a gaussian approximation. Simulations show that the approximation is reasonably accurate, and that the AML performance is close to tht of the ML scheme. COmparisons are also made with the ocnventional parallel acquistion scheme that treats the interference as random noise.
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