Research On Construction Of ZCZ Sequence Pairs Set

In the Approximately-synchronized code-division multiple-access (AS-CDMA) system, the synchronization error can be controlled in a few cycles within the chip. So people only requires spreading sequence in the synchronization error range (such as one or chip period) associated with or close to the ideal characteristics. ZCZ sequences satisfy this characteristic. ZCZ sequences with good performance, can reduce or eliminate multipath interference and multiple access interference (MAI). However, the ZCZ sequence design by many conditions, there are still some difficulties to look for them. ZCZ sequence pairs as the expansion of ZCZ sequence , as the AS-CDMA system of spread spectrum sequence can get more number of address code.First of all, in this paper, new methods for constructing set of ZCZ sequence pairs and ZCZ sequence pairs with large family size are proposed. First, almost optimal or optimal ZCZ sequence pairs set can be generated from the correlation product of unitary matrix and perfect sequence pairs with difference shift operation. Second, a new method for constructing ZCZ sequence pairs set with larger family size and longer zero correlation zone from a known one is presented.Secondly, a ZCZ sequence pairs set can be generated form orthogonal matrix pair with different shift, interleaved operation and n times recursive constructions; A new method for constructing ZCZ sequence pairs set with large family size from a known one is presented.Finally, in this paper, a new method for constructing ZCZ sequence pairs set with large zero correlation zone from a known one is presented, new ZCZ sequence pairs set can be generated from the original one with interleaved operation. The zero correlation zone of ZCZ sequence pairs set is M mtimes than the known one by m times recursive constructions with the new method.In addition, The methods are suitable for binary, ternary, four-phase and multiphase conditions. And the new ZCZ sequence pairs set has excellent performance that can satisfy Multi-users of AS-CDMA system.