Rapid sequence acquisition for DS/CDMA systems employing Kasami sequences

A sequence acquisition scheme based on sequential estimation and soft-decision combining methods is proposed and analyzed for direct-sequence CDMA systems employing Kasami sequences. The proposed technique is effective for Kasami (1987) sequences having very long periods. The algebraic properties of Kasami sequences are exploited to provide a very reliable estimate of the correct phase of the local shift register before tracking is attempted. This estimate is obtained by generating and combining multiple statistics for each chip that comprises the initial phase estimate. Expressions are derived for the mean and variance of the acquisition time, and the probabilities of acquisition, false dismissal, and false alarm. The proposed scheme compares well with the performance of alternative parallel acquisition schemes.<
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