In order to solve the various difficulties of low speed wireless communication,such as instantaneous fast fading,doppler spread and weak signal,a technical system of non-coherent M-ary orthogonal modulation and iterative decoding with diversity was proposed.Firstly,a system model of non-coherent M-ary orthogonal modulation was constructed,and a simplified demodulation and decoding based maximum mapping method was proposed.Secondly,the system scheme of non-coherent M-ary orthogonal modulation and soft iterative decoding with diversity was designed,and the key parameters for channel capacity limit was analyzed.The relationship between code rate and signal-to-noise ratio(SNR)was derived,and the performance analysis method of probability density with diversity merging signal was studied.Finally,using Monte Carlo simulation method,the system capacity performance was simulated and analyzed in AWGN channel and Rayleigh channel.The results indicate that using 16 diversity,32-ary orthogonal modulation,Turbo or LDPC iterative decoding,code rate of 2/3 and length of 384,the stable communication is achieved at the SNR of 3 dB in Rayleigh channel with the normalized doppler 0.5.The proposed method achieves reliable transmission with low SNR,which provides reference for the design of low-speed wireless communication system.
关键词
无线通信技术/多进制正交/非相干/瑞利信道/分集/概率密度
Key words
wireless communication technique/M-ary orthogonal/non-coherent/Rayleigh channel/diversity/probability density
维普
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