【扩频通信】扩频通信系统仿真含Matlab源码

1 简介

阐述了扩频通信的基本原理,主要性能指标及其工作特点,借助于MATLAB6.5软件建立扩频通信系统仿真模型并进行仿真,通过示波器直观地对扩频通信波形进行了分析.

2 部分代码

% Kasami codes​%option indicates sequence format​function[codes] = kasami(option)​blarge = 1;m=8; % m has to be evenN = 2^m -1;​code3 = zeros(1, N);  %2 codes for xor with circular shiftcode2 = zeros(1, N);code1 = BasicSeqK(m);​if blarge == 0    s = 2^(m/2) + 1; %decimation index    lim = 2^(m/2); % no of sequences    codes = zeros(lim, N);    codes(1, 1:N) = code1;​    %decimation process for creating code2    k = 0;​    for i=1:N        ind = mod(1 + k*s, N);        if ind == 0;            ind = N;        end        code2(i) = code1(ind);        k = k + 1;    end​    for i=2:lim        codes(i,1:N) = xor(code1,code2); %generating codes        circshift(code2, [0,-1]); %left shift    end    codes;else    % LARGE KASAMI SEQUENCE SET      d1 = 2.^(m/2)+1;  % decimation index1    d2 = 2.^((m+2)/2)+1;    % decimation index2    k = 0;​    %decimation process for creating code2​    for i=1:N        ind = mod(1 + k*d1, N);        if ind == 0;            ind = N;        end        code2(i) = code1(ind);        k = k + 1;    end​    %decimation process for creating code3​    k = 0;    for i=1:N        ind = mod(1 + k*d2, N);        if ind == 0;            ind = N;        end        code3(i) = code1(ind);        k = k + 1;    end​    lim = 2.^(m/2)*(2^m + 1); % the number of codes    codes = zeros(lim, N);​    codes(1, 1:N) = code1;     codes(2, 1:N) = code3;        k_seq1 = code1; % add by hzh at 061219           codesp3 = code3;    codesp2 = code2;​    lim1 = 2^m - 1;​    for i=3:lim1+2        codes(i,1:N) = xor(code1, code3);        code3 = circshift(code3, [0, -1]);    end​    lim2 = 2^(m/2)- 1;​    for j=i+1:lim2+i        codes(j,1:N) = xor(code1, code2);        code2 = circshift(code2, [0, -1]);    end​    code2 = codesp2;    code3 = codesp3;​    for i=j+1:lim2+j        codes(i,1:N) = xor(code3, code2);        code2 = circshift(code2, [0, -1]);    end​    for k = 3 : lim1+2        code2 = codesp2;        for j=1:lim2            i = i+1;            codes(i, 1:N) = xor(codes(k, 1:N), code2);            code2 = circshift(code2, [0, -1]);        end    endend​%converting 0 to -1​if option == 1    d=1:lim;    codes(d,1:N) = 2*(codes(d,1:N)-1)+1;end​

3 仿真结果

4 参考文献

[1]李江波, 索丽敏, 尚廷义. 扩频通信系统及MATLAB仿真[J]. 黑龙江科技信息, 2009(35):1.

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