Zero Correlation Zone Sequences from a Unified Construction of Perfect Polyphase Sequences

Abstract

Sequence families with Zero Correlation Zone (ZCZ) can be used in quasi-synchronous code-division multiple-access (QS-CDMA) communication systems. This paper proposes two methods for constructing polyphase ZCZ sequence sets by using a unified construction of perfect polyphase sequences. The first method generates sets of perfect sequences with zero cross-correlation zone, i.e., sets such that the out-of-phase autocorrelation of each sequence is zero and the cross-correlation of any two sequences in a set is zero in some zone around the origin. The second method produces sets of so-called interference-free sequences with zero autocorrelation zone, i.e., sets such that the cross-correlation of any two sequences in a set is zero at any shift and the autocorrelation of each sequence is zero in some zone around the origin. Moreover, each generated ZCZ sequence set is optimal with respect to the Tang-Fan-Matsufuji bound.