Ternary ZCZ Codes with Inter-Subgroup Zero-zones for Multiuser Communications

In this paper, we propose a construction of two sets of ternary zero correlation zone (ZCZ) codes for quasi-synchronous (QS) code-division multiple-access (CDMA) systems. The proposed spreading codes almost satisfy the theoretical limit of code size for a given code length and ZCZ. Codes from different sets are mutually orthogonal. Furthermore, odd number-indexed codes in a set with even number-indexed codes in the other set have also a ZCZ. The proposed construction is based on mutually orthogonal complementary sets and perfect sequences.