理论懒得推了，直接上代码吧。图也不上了，自己去画吧。

close all%% generate data source and map them to qpsk symbolsN = 512; M = 4; src = randi([1, M], N,1); qpsk_set = [1+1i -1+1i -1-1i 1-1i]'; src_sym =  qpsk_set(src); %% ifft and add cpcp_len = 32; src_mod = ifft(src_sym); src_mod = src_mod / max(abs(src_mod)); src_wave = [src_mod(end-cp_len+1:end); src_mod]; % add cp%% transmit sig through channel (isi and noise)h = [0.9 0.4 0.1]'; rx_wave = conv(src_wave, h); noise = randn(size(rx_wave)) / 1e15;rx_wave = rx_wave + noise; %% remove cp and fft sample_start = cp_len; rx_2fft = rx_wave(sample_start + 1:sample_start + N); % remove cprx_fft = fft(rx_2fft);  %% phase rotation compensation h_inverse_tmp1 = exp(-2*1i*pi*(0:N-1)'/N); h_inverse_tmp2 = h_inverse_tmp1.^2; h_inverse = 1 ./ ( 0.9 + 0.4 * h_inverse_tmp1 + 0.1 * h_inverse_tmp2 ); hat_src = h_inverse .* rx_fft; %% plot resultfigure;plot(src_sym,'ro'); figure; plot(hat_src,'b*');