walsh_sequence_generator.m

构建CDMA通信系统

<matlab> Hadamard矩阵实现CDMA信道walsh正交码
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%                                                                                     %
%  该函数通过输入因子生成相应阶数的哈达曼(Hadamard)矩阵    %
%  利用哈达曼矩阵得到正交的walsh矩阵，参数num为矩阵阶数    %
%                                                                                     %
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function [walsh_matrix] = walsh_sequence_generator(num)
if nargin < 1                                      % 如果输入参数为空，默认输出0阶哈达曼矩阵
    num = 0;
end
if rem(log2(num),1) ~= 0 | num < 0 | num == 1
    error('参数 num 必须是非负的正整数,且必须为2的幂次 !');
end
walsh_matrix = [];                             % 初始化输出walsh序列矩阵
if num == 0
    walsh_matrix = [1];                       % 参数为零的Hadamard矩阵
elseif num == 2
    walsh_matrix = [1 1;1 -1];              % 参数为2的2阶Hadamard矩阵
else
    walsh_matrix = [1 1;1 -1];
    for k = 1:log2(num)-1                    % 循环生成log2(num)阶Hadamard矩阵
        walsh_matrix = [walsh_matrix,walsh_matrix;walsh_matrix,-walsh_matrix]; 
    end    
end