Research On Application Of Sequence Pairs In Spread Spectrum Communication System

The perfect signal and its design method play an important part in the optimizing design in the area of modernistic communication, radar, sonar, navigation, space ranging and controlling and electronically antagonism systems. It is of theoretical and application importance to study all kinds of sequence properties in depth. An abundance of research results were published through several decades and further researches have been carried out regarding these theories.A new concept of perfect signal and a new correlation method are necessity stringency as the developing of technology. It can not only serve the needs of engineering but the importance is that a new concept and idea can be established as well, and the perfect signal can therefore be researched with a new viewpoint. How to apply the new signal in the existing communication system and the performance analysis are critical to its practice application.Spread spectrum communication modulate the information data with spreading sequence, then transform the modulated signal by a much more wider bandwidth. At the receiver, after demodulation and correlation disposal using the same spreading sequence, we can get back the information data exactly. Comparing with the ordinary narrowband communication method, spread spectrum communication has two notable characters: spreading sequence and correlation disposal. These two characters produce many advantages, such as anti-jamming, anti-noise, anti-Doppler effect, secrecy, multi-access ability, and so on. In the spread spectrum communication system, the spreading sequence is vital, its capability can impact the whole system's performance. At present the main spreading sequence include m sequence, Gold sequence and M sequence. But these spreading sequences only exist at some given length, 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 sequence, which bring many inconveniences. While the sequence pairs exists at any length, it can make up the shortage of the spreading sequence at present.In this paper, a new definition of spreading sequence-sequence pairs was introducedinto the spread spectrum communication system. According to the spreading sequence's technical requirements, this paper uses genetic algorithms to search hypo-perfect sequence pairs from length 8 to length 63, and some results with better correlation function than Gold sequenceare found. It also presents a new sequence pairs spread spectrum communication system, the system's performances are fundamentally studied in a simulated system and make a compare with Gold sequence spread spectrum communication system. The results prove that the performances of sequence pairs spread spectrum communication system are better than Gold sequence spread spectrum communication system in some ways.