clear;
clc;
s = rng(211); % 设置RNG状态的可重复性
numFFT = 1024; % FFT点的数量
numRBs = 50; % 资源块的数量
rbSize = 12; % 每个资源块的副载波数量
cpLen = 72; % 样本中的循环前缀长度
bitsPerSubCarrier = 6; % 2: QPSK, 4: 16QAM, 6: 64QAM, 8: 256QAM
snrdB =30; % 以dB为单位的SNR
toneOffset = 2.5; % 音调偏移或超额带宽（在副载波中）
L = 513; % 滤波器长度（=滤波器次序+ 1），奇数
numDataCarriers = numRBs*rbSize; % 子带中数据子载波的数量
halfFilt = floor(L/2);
n = -halfFilt:halfFilt;
% Sinc函数原型滤波器
pb = sinc((numDataCarriers+2*toneOffset).*n./numFFT);
% Sinc截断窗口
w = (0.5*(1+cos(2*pi.*n/(L-1)))).^0.6;
% 归一化的低通滤波器系数
fnum = (pb.*w)/sum(pb.*w);
% 过滤脉冲响应
h = fvtool(fnum, 'Analysis', 'impulse', ...
'NormalizedFrequency', 'off', 'Fs', 15.36e6);
h.CurrentAxes.XLabel.String = 'Time (\mus)';
h.FigureToolbar = 'off';
% 使用dsp过滤器对象进行过滤
filtTx = dsp.FIRFilter('Structure', 'Direct form symmetric', ...
'Numerator', fnum);
filtRx = clone(filtTx); % Rx的匹配过滤器
% QAM符号映射器
qamMapper = comm.RectangularQAMModulator( ...
'ModulationOrder', 2^bitsPerSubCarrier, 'BitInput', true, ...
'NormalizationMethod', 'Average power');
% 为谱图设置一个数字
hFig = figure('Position', figposition([46 50 30 30]), 'MenuBar', 'none');
axis([-0.5 0.5 -200 -20]);
hold on;
grid on
xlabel('Normalized frequency');
ylabel('PSD (dBW/Hz)')
title(['F-OFDM, ' num2str(numRBs) ' Resource blocks, ' ...
num2str(rbSize) ' Subcarriers each'])
% 生成数据符号
bitsIn = randi([0 1], bitsPerSubCarrier*numDataCarriers, 1);
symbolsIn = qamMapper(bitsIn);
% 将数据打包成OFDM符号
offset = (numFFT-numDataCarriers)/2; % 为通带中心
symbolsInOFDM = [zeros(offset,1); symbolsIn; ...
zeros(numFFT-offset-numDataCarriers,1)];
ifftOut = ifft(ifftshift(symbolsInOFDM));
%预先加上循环前缀
txSigOFDM = [ifftOut(end-cpLen+1:end); ifftOut];
% 使用零填充过滤器来刷新尾部。 获取发射信号
txSigFOFDM = filtTx([txSigOFDM; zeros(L-1,1)]);
%绘制功率谱密度（PSD）
[psd,f] = periodogram(txSigFOFDM, rectwin(length(txSigFOFDM)), ...
numFFT*2, 1, 'centered');
plot(f,10*log10(psd));
% 计算峰均功率比（PAPR）
PAPR = comm.CCDF('PAPROutputPort', true, 'PowerUnits', 'dBW');
[~,~,paprFOFDM] = PAPR(txSigFOFDM);
disp(['Peak-to-Average-Power-Ratio for F-OFDM = ' num2str(paprFOFDM) ' dB']);
% 绘制OFDM信号的功率谱密度（PSD）
[psd,f] = periodogram(txSigOFDM, rectwin(length(txSigOFDM)), numFFT*2, ...
1, 'centered');
hFig1 = figure('Position', figposition([46 15 30 30]));
plot(f,10*log10(psd));
grid on
axis([-0.5 0.5 -200 -20]);
xlabel('Normalized frequency');
ylabel('PSD (dBW/Hz)')
title(['OFDM, ' num2str(numRBs*rbSize) ' Subcarriers'])
%计算峰均功率比（PAPR）
PAPR2 = comm.CCDF('PAPROutputPort', true, 'PowerUnits', 'dBW');
[~,~,paprOFDM] = PAPR2(txSigOFDM);
disp(['Peak-to-Average-Power-Ratio for OFDM = ' num2str(paprOFDM) ' dB']);
%添加AWGN和Rayleigh
chan = rayleighchan(0.00001,100);
rxSig = filter(chan,txSigFOFDM);
rxtSig = awgn(rxSig, snrdB, 'measured');
% 接收匹配的过滤器,
rxSigFilt = filtRx(rxtSig);
% 考虑过滤器延迟
rxSigFiltSync = rxSigFilt(L:end);
% 删除循环前缀
rxSymbol = rxSigFiltSync(cpLen+1:end);
%执行FFT
RxSymbols = fftshift(fft(rxSymbol));
%选择数据副载波
dataRxSymbols = RxSymbols(offset+(1:numDataCarriers));
% 绘制接收符号星座图
switch bitsPerSubCarrier
case 2 % QPSK
refConst = qammod((0:3).', 4, 'UnitAveragePower', true);
case 4 % 16QAM
refConst = qammod((0:15).', 16,'UnitAveragePower', true);
case 6 % 64QAM
refConst = qammod((0:63).', 64,'UnitAveragePower', true);
case 8 % 256QAM
refConst = qammod((0:255).', 256,'UnitAveragePower', true);
end
constDiagRx = comm.ConstellationDiagram( ...
'ShowReferenceConstellation', true, ...
'ReferenceConstellation', refConst, ...
'Position', figposition([20 15 30 40]), ...
'MeasurementInterval', length(dataRxSymbols), ...
'Title', 'F-OFDM Demodulated Symbols', ...
'Name', 'F-OFDM Reception', ...
'XLimits', [-1.5 1.5], 'YLimits', [-1.5 1.5]);
constDiagRx(dataRxSymbols);
% 由于没有通道建模，因此通道均衡不是必要的
%解映射和BER计算
qamDemod = comm.RectangularQAMDemodulator('ModulationOrder', ...
2^bitsPerSubCarrier, 'BitOutput', true, ...
'NormalizationMethod', 'Average power');
BER = comm.ErrorRate;
% 执行艰难的决策并测量错误
rxBits = qamDemod(dataRxSymbols);
ber = BER(bitsIn, rxBits);
disp(['F-OFDM Reception, BER = ' num2str(ber(1)) ' at SNR = ' ...
num2str(snrdB) ' dB']);
%恢复RNG状态
rng(s);
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