Research Of Interference Suppression Technology In Wireless Spread Spectrum System Communication System

Spread spectrum technology is such a technology which firstly spreads the spectrum of information data, then transmit these information data. It uses spread code which isn't related with information data to spread information data sprectrum, so the spectrum of spread spectrum signal is far wider than information data's and data information energy is widely distributed in the whole spectrum of spread spectrum signal. as spread spectrum communication system adopts this kind of spread spectrum technology, it has merits of multiple access capability, concealation capability and strong interference suppression capability, and it has been widely used in the fields of military interference suppression communication and mobile communication.Interference is a unavoidable and severe factor in affecting the quality of communication system, if it isn't processed appropriately, it will severely affect the reliability of communication system and make communication system lose itself sense. In spread spectrum communication system, as it uses the method of spreading the spectrum of information data by spread sprectrum code, it has interference suppression capability to some extent.But in fact, interference comes from varieties of aspects and possibly has different characteristics, interference suppression capability of Spread spectrum communication is not sufficient, some necessary interference suppression technologies must be used to filter received signal including radio-frequency signal and varieties of interference, reduce system bite error rate(BER), and increase system interference suppression performance.Communication system adopted by this paper is Direct sequence spread spectrum communication system. Firstly, this paper introduces the implement process of Direct sequence spread spectrum communication system, secondly, introduces filter algorithms used in this paper, including time domain filter algorithm and frequency domain filter algorithm. Time domain filter algorithms include line, non-line and improved non-line prediction filter algorithm. Frequency domain filter algorithms include Threshold filter algorithm and Frequency block least mean square algorithm. Finally, this paper applys these filter algorithms to Direct sequence spread spectrum system and studies system bite error rate in different interference environments. The chief content of study is improved non-line prediction filter algorithm, this paper improves the non-line prediction filter in the aspects of filter structure and weight coefficient update algorithm, then analyses the improved filter's advantages from the angles of system bite error rate and power spectrum density, and compares it with the unimproved non-line prediction filter.