qpsk调制.zip_QPSK_QPSK信道估计_QPSK调制_QPSK调制 matlab_qpsk matlab

clear all; close all; clc; %% Constants fs = 76.8e6; %串行后采样率 ts = 1/fs; N_fft = 512; %FFT点数512 delta_freq = fs/N_fft; %子载波间隔 N_fft_2 = N_fft/2; N_CP = 32; %循环前缀点数 N_channel = 512; %实际的通道数300 N_frame_symbol = 140-4; %帧符号数 刚好一帧，有4个同步信号 N_shixi = 100; %时隙个数 N_ChildFrame = N_shixi/2; %子帧个数，每个子帧有2个时隙 N_frame = N_ChildFrame/10; %帧个数，每帧有10个子帧 N_symbol = (N_fft+N_CP)*(N_frame_symbol+4); SNR = 10; % SNR = 100; % doppler = 150e3:10e3:400e3;%:1000:10e4; FRM = N_channel*N_frame_symbol*2; % 2 bits是一个子载波 % 选择哪一种信道估计方式和插值方式 method_esti = 2; %信道估计方法 1表示LS, 2表示LS-DFT, 3表示MMSE method_inter = 1; %插值方式，1表示线性插值，2表示DFT插值 %% Initializations Modulator = comm.QPSKModulator('BitInput',true); AWGN = comm.AWGNChannel; DeModulator = comm.QPSKDemodulator('BitOutput',true); BitError = comm.ErrorRate; u = randi([0 1], FRM,1); % Generate random bits % u = zeros(81600,1); % 暂时不考虑信道交织编码，直接进行QPSK调制 mod_sig1 = step(Modulator,u); % QPSK Modulator figure; plot(mod_sig1,'o'); title('没加噪声时产生的复信号的星座图'); % mod_sig_noise = awgn(mod_sig1,SNR); % figure;plot(mod_sig_noise,'o');title(['加噪声时产生的复信号的星座图 SNR=',num2str(SNR),'10 dB']); % disp(['信噪比',num2str(SNR),'dB']); %% ifft mod_sig = reshape(mod_sig1,512,136); sig_ifft = ifft(mod_sig(:,1:end),512); % figure;plot(fftshift(10*log10(abs(fft(sig_ifft))))); %% 并串转换 [size_CP_l,size_CP_r] = size(sig_ifft); sig_serial = reshape(sig_ifft,1,size_CP_l*size_CP_r);%sig_ifft(:,1).'; %% 加多普勒 t = (0:(length(sig_serial)-1))*ts; f1 = 10; % f2 = 1/2/pi; % doppler = f1*t+360e3*120*sin(1/120*t); %多普勒 doppler = 0.2*delta_freq; % for doppler_loop=1:length(doppler) % for SRN_loop=1:length(SNR) % for doppler_loop=1:length(doppler) sig_serial_doppler = sig_serial.*exp(1i*2*pi*f1*t); sig_noise = awgn(sig_serial_doppler,SNR,'measured'); % figure;plot(fftshift(abs(fft(sig_serial_doppler))));title('发送信号并串转换后的频谱'); %% % sig_rx = sig_noise; % sig_fft = fft(sig_rx,512); sig_rx = reshape(sig_noise,512,136); sig_fft = fft(sig_rx(:,1:end),512); sig_rx2 = reshape(sig_fft,length(sig_noise),1);%sig_fft.'; rx_sign = step(DeModulator, sig_rx2); err_cnt = sum(abs(rx_sign(1:end/2)-u(1:end/2))); figure;plot(sig_rx2(1:end/2),'o'); % title(['相对频偏为',num2str(doppler(doppler_loop)/delta_freq)]); % bits_err(doppler_loop) = err_cnt/length(rx_sign); % bits_err(k) = BitError.step(tx_sign',rx_sign'); % end % figure;plot(rx_sign); EbN0_dB= SNR-3; figure semilogy(doppler/delta_freq,bits_err,'b*-'); xlabel('相对频偏');%Eb/N0 (dB) ylabel('BER');