Sequence acquisition of DS-CDMA systems employing Gold sequences

This paper considers sequence acquisition in direct-sequence spread-spectrum (DS/SS) systems that use Gold sequences as the multiple access pseudonoise (PN) sequence. When long PN sequences are used, the design of an acquisition scheme requires the characteristics of partial correlation of PN sequences. For ease of analytic design, the partial correlation of Gold sequences is approximated using a piecewise linearized upper bound model. Since the acquisition of PN sequence in direct-sequence code-division multiple access (DS-CDMA) systems can be formulated as testing two simple hypotheses, we apply fixed sample size (FSS) and sequential tests to the detection of phase alignment. When a sliding correlator-type structure is employed for the acquisition scheme, the acquisition performance of Gold-sequence-based DS-CDMA systems is analyzed and compared to that of m-sequence-based systems. Analytical results show that the use of Gold sequences requires a mean acquisition time quite comparable to the use of m-sequences. Finally, analytical results are verified by computer simulation.