Application of Soft-Decision Decoding in M-ary Spread Spectrum Communication System
It is widely applied that spread spectrum communication technology effectively improves the anti-interference ability of the system.As the frequency band resource becomes more and more crowded,it has paid more and more attention to M-ary spread spectrum because of its ability to balance bandwidth and transmission rate.Synchronization has always been the key technology in the M-ary spread Spectrum technology.The error performance of the synchronous head synchronization method and reference signal syn-chronization method is compared.The soft digital method is used as the output of digital modulation and demodulation to the decoder.Based on the log-likelihood ratio,a suboptimal soft information extraction method suitable for the M-ary spread spectrum system is proposed,and the influenced of hard decision and soft decision on the system is analyzed,respectively.The simulation results show that the error performance of the system is not significantly improved by the decision,compared with the hard decision decoding,the soft decision decoding reaches a gain of about 0.2 dB,with a bit error rate(BER)of 10-3.After the convolutional coding is added,the error performance of the whole system is analyzed,with the simulation parameter unchanged,compared with that of the direct se-quence spread spectrum(DSSS)system,the error performance of the system reaches a gain of about 5.2 dB,the soft decision deco-ding has a gain of about 1 dB over the hard decision decoding.By considering the coding efficiency,the influence of the soft decision and hard decision on the error performance of the system is analyzed separately.The results show that under the high signal-to-noise ratio,the error performance of the system is greatly improved,the soft decision decoding has a gain of about 0.7 dB over the hard de-cision decoding,with a BER of 10-3,the error performance of the soft decision decoding on the whole system reaches a gain of 2.5 dB.
M-ary spread spectrumconvolutional codingsoft decision decodingcode efficiencyBERwireless communication technology
万方数据
维普
