qam4_demod.m

OFDM通信系统抗多径衰落干扰研究,顺便求OFDM系统中关于频谱偏移的估计与补偿的

function [qam_out] = Qam4_demod(qam_in)
%% 4QAM 解调函数
%% 输入： 矩阵，列数必须是的的倍数
%% 输出： 矩阵，解调后的01序列矩阵
%% 之前必须调用过
global QamTable;
global bitPerSymbol ;
[m,n] = size(qam_in);
qam_out = zeros(m,n*bitPerSymbol);
% 判决
for k = 1:m
    delt = abs(reshape(qam_in(k,:), n, 1)*ones(1,4) - ones(n,1)*QamTable);  %求最近的点
    [tmp, index] = min(delt,[],2);    %得到索引值
    qam_outTmp = de2bi(index-1,bitPerSymbol,'left-msb');
    qam_out(k,:) = reshape(qam_outTmp',1,bitPerSymbol*n);
end