Research On Application Of Low/Zero Correlation Zone Sequence Pairs In Spread Spectrum Communication System

In the spread spectrum communication system, the spreading sequence is vital;its capability can impact the whole system's performance directly. At present the main spreading sequences include m sequence, Gold sequence and M sequence, but these spreading sequences only exist at some given length. For example: m sequence and Gold sequence exist only at 2~n—1 length, and M sequence exists only at 2~n length. In many engineering project we have to cut short these spreading sequences, which bring many inconveniences.By research, we find that the sending sequence and the receiving sequence can be not the same one, as long as these two sequences(called sequence pairs) satisfy some conditions, they can meet the demands of perfect signals completely. While the sequence pairs exists at any length, it can make up the shortage of the spreading sequence in practice. With the development of technology, new concepts of signal and correlation methods are introduced to meet the demands of practical engineering. Aiming at CDMA communication system, spreading sequence has perfect correlation properties only within the bound of synchronized error, Low/Zero correlation zone (LCZ/ZCZ) was proposed.In this paper, combining with sequence pairs and LCZ/ZCZ, a new definition of spreading sequence——LCZ/ZCZ sequence pairs was introduced into the spread spectrum communication system. According to the spreading sequence's technical requirements, this paper used genetic algorithms to search LCZ/ZCZ sequence pairs within length 63, and some results are good. The results show that the sequence pairs have rather long LCZ/ZCZ and large main peak, and genetic algorithm is feasible in optimizing LCZ/ZCZ sequence pairs.It also presents a new spread spectrum communication system based on LCZ/ZCZ sequence pairs, the system's performances are fundamentally studied in a simulated system by Matlab and make a compare with Gold sequence spread spectrum communication system. The results prove that the performances of LCZ/ZCZ sequence pairs spread spectrum communication system are better than Gold sequence spread spectrum communication system in some ways.