channel ="GaussianNoise";ifstrcmpi(channel,"OverTheAir") deviceName ="Pluto"; channelNumber =5; frequencyBand =2.4; txGain =-10;elseifstrcmpi(channel,"GaussianNoise")% Specify SNR of received signal for a simulated channelSNR =20;end

% Setup handle for image plotif~exist('imFig','var') || ~ishandle(imFig)%#okimFig = figure; imFig.NumberTitle ='off'; imFig.Name ='Image Plot'; imFig.Visible ='off';elseclf(imFig);% Clear figureimFig.Visible ='off';end% Setup Spectrum viewerspectrumScope = spectrumAnalyzer(...SpectrumType='power-density',...Title='Received Baseband WLAN Signal Spectrum',...YLabel='Power spectral density',...Position=[69 376 800 450]);% Setup the constellation diagram viewer for equalized WLAN symbolsrefQAM = wlanReferenceSymbols('64QAM'); constellation = comm.ConstellationDiagram(...Title='Equalized WLAN Symbols',...ShowReferenceConstellation=true,...ReferenceConstellation=refQAM,...Position=[878 376 460 460]);

% Input an image file and convert to binary streamfileTx ='peppers.png';% Image file namefData = imread(fileTx);%从文件读取图像数据scale =0.2;% Image scaling factororigSize = size(fData);% Original input image sizescaledSize = max(floor(scale.*origSize(1:2)),1);% Calculate new image sizeheightIx = min(round(((1:scaledSize(1))-0.5)./scale+0.5),origSize(1)); widthIx = min(round(((1:scaledSize(2))-0.5)./scale+0.5),origSize(2)); fData = fData(heightIx,widthIx,:);% Resize imageimsize = size(fData);% Store new image sizetxImage = fData(:);% Plot transmit imageimFig.Visible ='on'; subplot(211); imshow(fData); title('Transmitted Image'); subplot(212); title('Received image appears here...'); set(gca,'Visible','off');

set(findall(gca,'type','text'),'visible','on');

msduLength =2304;% MSDU length in bytesnumMSDUs = ceil(length(txImage)/msduLength); padZeros = msduLength-mod(length(txImage),msduLength); txData = [txImage;zeros(padZeros,1)]; txDataBits = double(reshape(de2bi(txData, 8)',[],1));% Divide input data stream into fragmentsbitsPerOctet = 8; data = zeros(0,1);fori=0:numMSDUs-1% Extract image data (in octets) for each MPDUframeBody = txData(i*msduLength+1:msduLength*(i+1),:);% Create MAC frame configuration object and configure sequence numbercfgMAC = wlanMACFrameConfig(FrameType='Data',SequenceNumber=i);% Generate MPDU[psdu, lengthMPDU]= wlanMACFrame(frameBody,cfgMAC,OutputFormat='bits');% Concatenate PSDUs for waveform generationdata = [data; psdu];%#okend

nonHTcfg = wlanNonHTConfig;% Create packet configurationnonHTcfg.MCS = 6;% Modulation: 64QAM Rate: 2/3nonHTcfg.NumTransmitAntennas = 1;% Number of transmit antennachanBW = nonHTcfg.ChannelBandwidth; nonHTcfg.PSDULength = lengthMPDU;% Set the PSDU length

scramblerInitialization = randi([1 127],numMSDUs,1);

osf =1.5; sampleRate = wlanSampleRate(nonHTcfg);% Nominal sample rate in Hz% Generate baseband NonHT packets separated by idle timetxWaveform = wlanWaveformGenerator(data,nonHTcfg,...NumPackets=numMSDUs,IdleTime=20e-6,...ScramblerInitialization=scramblerInitialization,...OversamplingFactor=osf);

ifstrcmpi(channel,"OverTheAir")% Transmitter propertiessdrTransmitter = sdrtx(deviceName); sdrTransmitter.BasebandSampleRate = sampleRate*osf; sdrTransmitter.CenterFrequency = wlanChannelFrequency(channelNumber,frequencyBand); sdrTransmitter.Gain = txGain;% Pass the SDR I/O directly to host skipping FPGA on Zynq Radio or USRP% Embedded Series Radioif~strcmpi(deviceName,"Pluto") sdrTransmitter.ShowAdvancedProperties = true; sdrTransmitter.BypassUserLogic = true;endfprintf('\nGenerating WLAN transmit waveform:\n')% Scale the normalized signal to avoid saturation of RF stagespowerScaleFactor = 0.8; txWaveform = txWaveform.*(1/max(abs(txWaveform))*powerScaleFactor);% Transmit RF waveformtransmitRepeat(sdrTransmitter,txWaveform);end

ifstrcmpi(channel,"OverTheAir") sdrReceiver = sdrrx(deviceName); sdrReceiver.BasebandSampleRate = sdrTransmitter.BasebandSampleRate; sdrReceiver.CenterFrequency = sdrTransmitter.CenterFrequency; sdrReceiver.OutputDataType ='double';if~strcmpi(deviceName,"Pluto") sdrReceiver.ShowAdvancedProperties = true; sdrReceiver.BypassUserLogic = true;end% Configure the capture length equivalent to twice the length of the% transmitted signal, this is to ensure that PSDUs are received in order.% On reception the duplicate MAC fragments are removed.sdrReceiver.SamplesPerFrame = 2*length(txWaveform); fprintf('\nStarting a new RF capture.\n') rxWaveform = capture(sdrReceiver,sdrReceiver.SamplesPerFrame,'Samples');elseifstrcmpi(channel,"GaussianNoise") rxWaveform = awgn(txWaveform,SNR,'measured');else% No ImpairmentsrxWaveform = txWaveform;end

spectrumScope.SampleRate = sampleRate*osf; spectrumScope(rxWaveform); release(spectrumScope);

aStop = 40;% Stopband attenuationofdmInfo = wlanNonHTOFDMInfo('NonHT-Data',nonHTcfg);% OFDM parametersSCS = sampleRate/ofdmInfo.FFTLength;% Subcarrier spacingtxbw = max(abs(ofdmInfo.ActiveFrequencyIndices))*2*SCS;% Occupied bandwidth[L,M] = rat(1/osf); maxLM = max([L M]); R = (sampleRate-txbw)/sampleRate; TW = 2*R/maxLM;% Transition widthb= designMultirateFIR(L,M,TW,aStop);

firrc = dsp.FIRRateConverter(L,M,b); rxWaveform = firrc(rxWaveform);

displayFlag =false;

rxWaveformLen = size(rxWaveform,1); searchOffset = 0;% Offset from start of the waveform in samples

ind = wlanFieldIndices(nonHTcfg); Ns = ind.LSIG(2)-ind.LSIG(1)+1;% Number of samples in an OFDM symbol% Minimum packet length is 10 OFDM symbolslstfLen = double(ind.LSTF(2));% Number of samples in L-STFminPktLen = lstfLen*5; pktInd = 1; fineTimingOffset = []; packetSeq = []; rxBit = [];% Perform EVM calculationevmCalculator = comm.EVM(AveragingDimensions=[1 2 3]); evmCalculator.MaximumEVMOutputPort = true;

while(searchOffset+minPktLen)<=rxWaveformLen% Packet detectpktOffset = wlanPacketDetect(rxWaveform,chanBW,searchOffset,0.5);% Adjust packet offsetpktOffset = searchOffset+pktOffset;ifisempty(pktOffset) || (pktOffset+double(ind.LSIG(2))>rxWaveformLen)ifpktInd==1 disp('** No packet detected **');endbreak;end% Extract non-HT fields and perform coarse frequency offset correction% to allow for reliable symbol timingnonHT = rxWaveform(pktOffset+(ind.LSTF(1):ind.LSIG(2)),:); coarseFreqOffset = wlanCoarseCFOEstimate(nonHT,chanBW); nonHT = frequencyOffset(nonHT,sampleRate,-coarseFreqOffset);% Symbol timing synchronizationfineTimingOffset = wlanSymbolTimingEstimate(nonHT,chanBW);% Adjust packet offsetpktOffset = pktOffset+fineTimingOffset;% Timing synchronization complete: Packet detected and synchronized% Extract the non-HT preamble field after synchronization and% perform frequency correctionif(pktOffset<0) || ((pktOffset+minPktLen)>rxWaveformLen) searchOffset = pktOffset+1.5*lstfLen;continue;endfprintf('\nPacket-%d detected at index %d\n',pktInd,pktOffset+1);% Extract first 7 OFDM symbols worth of data for format detection and% L-SIG decodingnonHT = rxWaveform(pktOffset+(1:7*Ns),:); nonHT = frequencyOffset(nonHT,sampleRate,-coarseFreqOffset);% Perform fine frequency offset correction on the synchronized and% coarse corrected preamble fieldslltf = nonHT(ind.LLTF(1):ind.LLTF(2),:);% Extract L-LTFfineFreqOffset = wlanFineCFOEstimate(lltf,chanBW); nonHT = frequencyOffset(nonHT,sampleRate,-fineFreqOffset); cfoCorrection = coarseFreqOffset+fineFreqOffset;% Total CFO% Channel estimation using L-LTFlltf = nonHT(ind.LLTF(1):ind.LLTF(2),:); demodLLTF = wlanLLTFDemodulate(lltf,chanBW); chanEstLLTF = wlanLLTFChannelEstimate(demodLLTF,chanBW);% Noise estimationnoiseVarNonHT = helperNoiseEstimate(demodLLTF);% Packet format detection using the 3 OFDM symbols immediately% following the L-LTFformat = wlanFormatDetect(nonHT(ind.LLTF(2)+(1:3*Ns),:),...chanEstLLTF,noiseVarNonHT,chanBW); disp([' 'format' format detected']);if~strcmp(format,'Non-HT') fprintf(' A format other than Non-HT has been detected\n'); searchOffset = pktOffset+1.5*lstfLen;continue;end% Recover L-SIG field bits[recLSIGBits,failCheck] = wlanLSIGRecover(...nonHT(ind.LSIG(1):ind.LSIG(2),:),...chanEstLLTF,noiseVarNonHT,chanBW);iffailCheck fprintf(' L-SIG check fail \n'); searchOffset = pktOffset+1.5*lstfLen;continue;elsefprintf(' L-SIG check pass \n');end% Retrieve packet parameters based on decoded L-SIG[lsigMCS,lsigLen,rxSamples] = helperInterpretLSIG(recLSIGBits,sampleRate);if(rxSamples+pktOffset)>length(rxWaveform) disp('** Not enough samples to decode packet **');break;end% Apply CFO correction to the entire packetrxWaveform(pktOffset+(1:rxSamples),:) = frequencyOffset(...rxWaveform(pktOffset+(1:rxSamples),:),sampleRate,-cfoCorrection);% Create a receive Non-HT config objectrxNonHTcfg = wlanNonHTConfig; rxNonHTcfg.MCS = lsigMCS; rxNonHTcfg.PSDULength = lsigLen;% Get the data field indices within a PPDUindNonHTData = wlanFieldIndices(rxNonHTcfg,'NonHT-Data');% Recover PSDU bits using transmitted packet parameters and channel% estimates from L-LTF[rxPSDU,eqSym] = wlanNonHTDataRecover(rxWaveform(pktOffset+...(indNonHTData(1):indNonHTData(2)),:),...chanEstLLTF,noiseVarNonHT,rxNonHTcfg); constellation(reshape(eqSym,[],1));% Current constellationrelease(constellation); refSym = wlanClosestReferenceSymbol(eqSym,rxNonHTcfg); [evm.RMS,evm.Peak] = evmCalculator(refSym,eqSym);% Decode the MPDU and extract MSDU[cfgMACRx,msduList{pktInd},status] = wlanMPDUDecode(rxPSDU,rxNonHTcfg);%#ok<*SAGROW>ifstrcmp(status,'Success') disp(' MAC FCS check pass');% Store sequencing informationpacketSeq(pktInd) = cfgMACRx.SequenceNumber;% Convert MSDU to a binary data streamrxBit{pktInd} = reshape(de2bi(hex2dec(cell2mat(msduList{pktInd})),8)',[],1);else% Decoding failedifstrcmp(status,'FCSFailed')% FCS faileddisp(' MAC FCS check fail');else% FCS passed but encountered other decoding failuresdisp(' MAC FCS check pass');end% Since there are no retransmissions modeled in this example, we% extract the image data (MSDU) and sequence number from the MPDU,% even though FCS check fails.% Remove header and FCS. Extract the MSDU.macHeaderBitsLength = 24*bitsPerOctet; fcsBitsLength = 4*bitsPerOctet; msduList{pktInd} = rxPSDU(macHeaderBitsLength+1:end-fcsBitsLength);% Extract and store sequence numbersequenceNumStartIndex = 23 * bitsPerOctet + 1;层层序eNumEndIndex = 25*bitsPerOctet-4; packetSeq(pktInd) = bi2de(rxPSDU(sequenceNumStartIndex:sequenceNumEndIndex)');% MSDU binary data streamrxBit{pktInd} = double(msduList{pktInd});end% Display decoded informationifdisplayFlag fprintf(' Estimated CFO: %5.1f Hz\n\n',cfoCorrection);%#ok<*UNRCH>disp(' Decoded L-SIG contents: '); fprintf(' MCS: %d\n',lsigMCS); fprintf(' Length: %d\n',lsigLen); fprintf(' Number of samples in packet: %d\n\n',rxSamples); fprintf(' EVM:\n'); fprintf(' EVM peak: %0.3f%% EVM RMS: %0.3f%%\n\n',...evm.Peak,evm.RMS); fprintf(' Decoded MAC Sequence Control field contents:\n'); fprintf(' Sequence number: %d\n\n',packetSeq(pktInd));end% Update search indexsearchOffset = pktOffset+double(indNonHTData(2));% Finish processing when a duplicate packet is detected. The% recovered data includes bits from duplicate frame% Remove the data bits from the duplicate frameiflength(unique(packetSeq)) < length(packetSeq) rxBit = rxBit(1:length(unique(packetSeq))); packetSeq = packetSeq(1:length(unique(packetSeq)));breakendpktInd = pktInd+1;end

ifstrcmpi(channel,"OverTheAir") release(sdrTransmitter); release(sdrReceiver);end

if~(isempty(fineTimingOffset) || isempty(pktOffset)) rxData = cell2mat(rxBit);% Remove duplicate packets if any. Duplicate packets are located at the% end of rxDataiflength(packetSeq)>numMSDUs numDupPackets = size(rxData,2)-numMSDUs; rxData = rxData(:,1:end-numDupPackets);end% Initialize variables for while loopstartSeq = []; i=-1;% Only execute this if one of the packet sequence values have been decoded% accuratelyifany(packetSeqwhileisempty(startSeq)% This searches for a known packetSeq valuei = i + 1; startSeq = find(packetSeq==i);end% Circularly shift data so that received packets are in order for image reconstruction. It% is assumed that all packets following the starting packet are received in% order as this is how the image is transmitted.rxData = circshift(rxData,[0 -(startSeq(1)-i-1)]);% Order MAC fragments% Perform bit error rate (BER) calculation on reordered databitErrorRate = comm.ErrorRate;呃= bitErrorRate (double(rxData(:)),...txDataBits(1:length(reshape(rxData,[],1)))); fprintf(' \nBit Error Rate (BER):\n'); fprintf(' Bit Error Rate (BER) = %0.5f\n',err(1)); fprintf(' Number of bit errors = %d\n',err(2)); fprintf(' Number of transmitted bits = %d\n\n',length(txDataBits));enddecData = bi2de(reshape(rxData(:),8,[])');% Append NaNs to fill any missing image dataiflength(decData)elsedecData = decData(1:length(txImage));end% Recreate image from received datafprintf('\nConstructing image from received data.\n'); receivedImage = uint8(reshape(decData,imsize));% Plot received imageifexist('imFig','var') && ishandle(imFig)% If Tx figure is openfigure(imFig); subplot(212);elsefigure; subplot(212);endimshow(receivedImage); title(sprintf('Received Image'));end