The Research For Sequence Optimization And Sequence Fuzzy Judgment In Parallel Combinatory Spread Spectrum Communication

Parallel combinatory spread spectrum communication technology developed from the traditional direct spread spectrum communication technology, it has the advantage of spread spectrum technology, such as strong anti-interference performance, good concealment, in addition to, more bandwidth and high efficiency, it is suitable for high-speed and ad hoc networks spread spectrum communications. Parallel combinatory spread spectrum communication technology has good prospects for the development and application prospects.In this paper,the research object is the parallel combinatory spread spectrum communication,the target is to improve anti-interference ability,reduce the BER of the system. The article introduce the sequence optimization and information resent to reduce the system BER, based on the detailed analysis of the principle of parallel combinatory spread spectrum communication. The main content includes the following several aspects:1. Analysis the reason of interference between sequences in parallel combinatory spread spectrum communication system, and commonly spread spectrum sequence random characteristics, including the length, autocorrelation, balance and the cross-correlation of the spread spectrum sequences. Analysis the influence of the spread spectrum sequence framework and the intrinsic relationship between the system performance, put forward suitable for fast optimization method for parallel combinatory spread spectrum communication, correlation diagram method, grouping group legal based on the direct method,to reduce the computational complexity of sequence optimization, and to apply to large number sequence optimization, to select the most suitable for communication system,improve the transmission reliability, privacy and security. In addition, the parallel combinatory spread spectrum communication system use the chaotic sequence as spread spectrum codes. The Chaotic sequence has some advantages,such as huge number,random length and good correlation, etc. After chaotic sequence, the chaotic sequence is more applicable to the parallel combinatory spread spectrum communication system, improve the anti-jamming capability, multi-addressing capability and anti-detection capabilities for the system.2. Analysis the BER under the large signal-to-noise ratio system,put forward a parallel combination sequence spread spectrum communication judgment fuzzy concept in parallel combination sequence spread spectrum communication, In order to correct errors caused by fuzzy judgment, put forward a ARQ method with adaptive fuzzy threshold,when the fuzzy judgment take place, start ARQ mechanism, makes the sending end retransmission of information , compare the relationship between the sequences, to correct the errors, and to ensure the information is correct. This method can greatly reduce the BER caused by fuzzy judgment, improve system transmission reliability . Adjust the fuzzy judgment threshold based on the successful retransmission threshold, make the judgment threshold has adaptivity.Higher threshold will reduce the efficiency of the communication system by starts a retransmission mechanism; lower threshold will not achieve the anti- blur function sequence.3. Design the correlator for parallel combinatory spread spectrum communication receiver, including carrier module, code modules and related integral module, frame unlock module and register module, etc.Simulation results show: Sequence optimization and sequence fuzzy judgment method can greatly improve the anti-interference performance for parallel combinatory spread spectrum system, reduce BER, with a more high application value.