Study On ZCZ Sequence Design Based On The Interleaved Technique

The spreading sequence designs are one of the key points of the spreading-spectrum communication systems. Ideal spreading codes used for CDMA system should have impulsive-like auto-correlation functions and zero cross-correlation functions. Unfortunately, it has been shown that such ideal codes do not exist. Recently, the research on spreading sequences with zero correlation zone(ZCZ) is being paid much attention. These sequences have ideal correaltion functions within a specific zone, which can be used in quasi-synchronous CDMA system, where the synchronization among users can be controlled within permissible time difference.Based on interleaved technique, the design of sequence with zero correlation zone is studied.After analysing the methods of designing several known spreading sequences with zero correlation zone and matrix transform, the new conclusion has been made. It has been shown that the designs of these ZCZ sequences are based on interleaved technique. So the thesis describes the spreading sequence designs with interleaved technique again, and combines them to the interleaved design of spreading sequences with zero correlation zone.Through analyse of the structure and characters of interleaved sequences, and learning from the designs of ZCZ sequence and structure of interleaved sequences, the author gets method of designing three kinds of ZCZ sequence, that is, generalized, restricted and joint restricted-generalized interleave designs of ZCZ sequence. According to the mathematical bound, the designs of ZCZ sequence based on interleaved technique can not only design the ZCZ sequence set with a large family sequence, but also it can reach or approach the mathematical bound.The ZCZ sequence set designed by the author can be applied to the quasi-synchronous CDMA system and reduce even eliminate co-channel interference, so increase the system capability.