毕业设计：基于802.11a的OFDM的Matlab仿真，实现信道估计和同步源码

clear; clc; %% 参数设置 Nfft = 64; carries = 52; % Nps = 14; % 导频间隔 Cpilot = 4; % 导频子载波个数 Cdata = carries - Cpilot; % 数据子载波个数 Ipilot = [-21 -7 7 21] + Nfft/2; % 导频子载波位置 Idata = [-26:-22 -20:-8 -6:-1 1:6 8:20 22:26] + Nfft/2; % 数据子载波位置 0为直流子载波 Ncp = Nfft / 4; % 保护间隔长度 Nsym_cp = Nfft + Ncp; % 80 Nframe = 100; % 每帧符号数 Nts = 2; % 每帧训练符号符号数 Nsym = Nframe - Nts; % 每帧数据符号数 Nbpsc2 = 2; % QPSK 每个子载波编码比特 导频 Nbpsc4 = 4; % 16QAM 每个子载波编码比特 数据 SNR = 30; % 信噪比 %% 导频 pilot = [1 1 1 -1]; %% 生成信号 Ndata = Cdata * Nsym * Nbpsc4; % 随机信号总比特数 data=randi([0,1],1,Ndata); % plot(data); %% 信号使用16QAM调制 MODdata = MOD_QAM(data); plot(MODdata, '*'); axis([-5 5 -5 5]); MODdata_REAL = real(MODdata); MODdata_IMAG = imag(MODdata); %% 串并转换 PARAdata = reshape(MODdata, Nsym, Cdata); %% 子载波映射 MAPcarries = zeros(Nsym,Nfft); % 导频子载波映射 for m = 1:Cpilot for n = 1:Nsym MAPcarries(n, Ipilot(m)) = pilot(m); end end % 数据子载波映射 for n = 1:Cdata MAPcarries(:, Idata(n)) = PARAdata(:, n); end %% 对每个符号进行传输 RX_PARAdata = []; for sym = 1:Nsym %% IFFT IFFTcarries= IFFT_MOD(MAPcarries(sym, :), Nfft); % plot(0:Nfft-1,abs(IFFTcarries)); %% 添加循环前缀 cp = IFFTcarries(Nfft-Ncp+1:Nfft); CPcarries = [cp, IFFTcarries]; % plot(0:Nsym_cp-1,abs(CPcarries)); % %% 并串转换 % SERIdata = reshape(CPcarries, 1, Nsym*Nsym_cp); % % %% 生成长训练符号 % Lts = [1 1 -1 -1 1 1 -1 1 -1 1 1 1 1 1 1 -1 -1 1 1 -1 1 -1 1 1 1 1 0 1 -1 -1 1 1 -1 1 -1 1 -1 -1 -1 -1 -1 1 1 -1 -1 1 -1 1 -1 1 1 1 1]; % [1x53] 调制因子 % TScarrier = zeros(1, Nfft); % [1x64] % TScarrier(6:58) = Lts; % [1x64] % 一个频域训练符号 % IFFT_TScarrier = ifft(TScarrier, Nfft); % [1x64] 一个时域训练符号 % ts = [IFFT_TScarrier(Nfft-Nts*Ncp+1:Nfft) IFFT_TScarrier IFFT_TScarrier]; % [1x160] 时域训练符号 2CP 2TS % plot(0:Nts*Nsym_cp-1,abs(ts)); % % %% 添加训练符号 % stream = [ts SERIdata]; % Lstream = length(stream); % plot(0:Lstream-1,abs(stream)); %% 信道 OFDMsym = CPcarries; channel = [(randn+1j*randn) (randn+1j*randn)/2]; % 2抽头信道 FFTchannel = FFT_MOD(channel, Nfft); % 频域 Lchannel = length(FFTchannel); % 信道长度 PdBchannel = 10*log10(abs(FFTchannel.*conj(FFTchannel))); % 信道功率 RXstream = conv(OFDMsym, channel); % 接收信号 RX_AWGNstream = awgn(RXstream, SNR, 'measured'); % 添加高斯噪声 %% 去CP RXdata = RX_AWGNstream(Ncp+1:Nsym_cp); %% FFT RX_FFTdata = FFT_MOD(RXdata, Nfft); %% LS信道估计 H_LS = LS_CE(RX_FFTdata, pilot, Ipilot, Nfft, Cpilot); % 使用三次样条插值 %% 信道补偿 RX_LSdata = RX_FFTdata./H_LS; %% 串并转换 RX_PARAdata = [RX_PARAdata; RX_LSdata]; end %% 子载波解映射 DEMAPcarries = zeros(Nsym, Cdata); for b = 1:Cdata DEMAPcarries(:, b) = RX_PARAdata(:, Idata(b)); end %% 并串转换 RX_SERIdata = reshape(DEMAPcarries, 1, Cdata*Nsym); %% QAM解调 DEMODdata = DEMOD_QAM(RX_SERIdata); x = DEMODdata + data; m = length(find(x == 1)); z = m/960; %% 绘图分析 plot(DEMAPcarries, 'r*'); axis(2*[-1 1 -1 1]);