ofdm_demod.m

来自「OFDM的详细仿真代码」· M 代码 · 共 24 行

function [training_sym ,data_sym] = ofdm_demod(fine_freq_out,PrefixRatio,N_subc,N_sym,N_tran_sym,N_Rx_ant)

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% 实现OFDM的基本解调

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

training_sym = zeros(N_subc,1,N_Rx_ant);
data_sym = zeros(N_subc,N_sym,N_Rx_ant);
cp_len = round(PrefixRatio*N_subc);

for ant = 1:N_Rx_ant
    ofdm_tmp = reshape( fine_freq_out(1,:,ant), N_subc*(1+PrefixRatio) , N_sym + N_tran_sym - 1 );
    cp_cut = ofdm_tmp( cp_len + 1:end,: );
    % fft乘1/sqrt(N_subc)以保证变换前后能量不变
    % 我们假设频域的样点是在[-fs/2  fs/2]中的, fs是采样频率
    % fftshift目的是使得变换后的频域样点在[-fs/2  fs/2]中,而不是[0 fs]中
    ofdm_sym(:,:,ant) = fftshift(1/sqrt(N_subc) * fft( cp_cut ), 1);
end

training_sym = ofdm_sym(:,1,:);             % 用于信道估计的训练符号
data_sym = ofdm_sym(:, 2:N_sym+1 ,:);     % 数据OFDM符号, 包括导频符号