Abstract:

A New method for constructing set of zero correlation zone (ZCZ) sequence pairs and ZCZ sequence pairs with large family size is proposed. It can be used in approximatelysynchronized codedivision multipleaccess (ASCDMA) system for the reduction or elimination of the multipath interference and multiple access interference (MAI) of the system. The capacity of increasing users is large with satisfactory. First, almost 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, it can be generated from the correlation product of unitary matrix and original ZCZ sequence pairs set with difference shift operation. These methods are applied to binary, ternary quadricphase and multiphase case. Performances of ZCZ sequence pairs set constructed by the proposed methods are so good that they can satisfy requirements of ASCDMA system within the range of allowed time delay chips.

Key words: approximatelysynchronized codedivision multipleaccess, perfect sequence pairs, zero correlation zone, correlation product, unitary matrix