i think that this is nearly the beginning of task 1

lab_4/calc_doppler_freq.m

@@ -0,0 +1,3 @@
+function result = calc_doppler_freq(rrv, carrier_freq)
+    result = rrv * carrier_freq / physconst('LightSpeed');
+end

lab_4/create_baseline_configuration.m

@@ -0,0 +1,75 @@
+function [cfgEHT, simParameters, channel, chInfo, maxChDelay, satelliteDopplerShift, chanBW] = create_baseline_configuration(profile, ...
+                                     bandwidth_mhz, ...
+                                     include_free_space_pathloss, ...
+                                     delay_model, ...
+                                     carrier_frequency, ...
+                                     elevation_angle, ...
+                                     mobile_speed, ...
+                                     mobile_altitude, ...
+                                     satellite_altitude, ...
+                                     random_stream, ...
+                                     seed, ...
+                                     tx_antenna_count, ...
+                                     rx_antenna_count, ...
+                                     apep, ...
+                                     mcs)
+
+    switch bandwidth_mhz
+        case 20
+            chanBW = 'CBW20';
+        case 40
+            chanBW = 'CBW40';
+        case 80
+            chanBW = 'CBW80';
+        case 160
+            chanBW = 'CBW160';
+        case 320
+            chanBW = 'CBW320';
+        otherwise
+            error("Not supported bandwidth!");
+    end
+    
+    cfgEHT = wlanEHTMUConfig(chanBW);
+    cfgEHT.User{1}.APEPLength = apep;
+    cfgEHT.NumTransmitAntennas = tx_antenna_count;
+    cfgEHT.User{1}.NumSpaceTimeStreams = 1;
+    cfgEHT.User{1}.MCS = mcs;
+    fs = wlanSampleRate(chanBW);
+
+    simParameters.IncludeFreeSpacePathLoss = include_free_space_pathloss;
+    simParameters.DelayModel = delay_model;
+    simParameters.CarrierFrequency = carrier_frequency;
+    simParameters.ElevationAngle = elevation_angle;
+    simParameters.MobileSpeed = mobile_speed;
+    simParameters.MobileAltitude = mobile_altitude;
+    simParameters.SatelliteAltitude = satellite_altitude;
+    simParameters.SampleRate = fs;
+    simParameters.RandomStream = random_stream;
+    simParameters.Seed = seed;
+    simParameters.NumTransmitAntennas = tx_antenna_count;
+    simParameters.NumReceiveAntennas = rx_antenna_count;
+    
+    simParameters.NTNChannelType = "TDL";
+    simParameters.DelayProfile = "NTN-TDL-" + profile;
+    simParameters.DelaySpread = 30e-9;
+        
+    c = physconst("lightspeed");
+    satelliteDopplerShift = dopplerShiftCircularOrbit( ...
+        simParameters.ElevationAngle,simParameters.SatelliteAltitude, ...
+        simParameters.MobileAltitude,simParameters.CarrierFrequency);
+    
+    channel = nrTDLChannel;
+    channel.DelayProfile = simParameters.DelayProfile;
+    channel.DelaySpread = simParameters.DelaySpread;
+    channel.SatelliteDopplerShift = satelliteDopplerShift;
+    channel.MaximumDopplerShift = simParameters.MobileSpeed*simParameters.CarrierFrequency/c;
+    channel.NumTransmitAntennas = simParameters.NumTransmitAntennas;
+    channel.NumReceiveAntennas = simParameters.NumReceiveAntennas;
+    
+    channel.SampleRate = simParameters.SampleRate;
+    channel.RandomStream = simParameters.RandomStream;
+    channel.Seed = simParameters.Seed;
+    
+    chInfo = info(channel);
+    maxChDelay = ceil(max(chInfo.PathDelays*channel.SampleRate)) + chInfo.ChannelFilterDelay;
+end

lab_4/lab_4.m

@@ -0,0 +1,43 @@
+carrier_frequency = 2.4e9;
+wifi_be_subcarrier_spacing = 78.125e3;
+leo_altitude = 600e3;
+bandwidth = 20; 
+mcs = 2;
+apep = 1000;
+tx_antenna_count = 1;
+rx_antenna_count = 1;
+
+elevation_angle = 50;
+
+random_stream = "mt19937ar with seed";
+seed = 666;
+
+ntn_tdl_delay_profiles = ["A" "B" "C" "D"];
+
+[cfgEHT, simParameters, channel, chInfo, maxChDelay, satelliteDopplerShift, chanBW] = ...
+    create_baseline_configuration(ntn_tdl_delay_profiles(3), bandwidth, false, "None", ...
+                       carrier_frequency, elevation_angle, 0, ...
+                       0, leo_altitude, random_stream, ...
+                       seed, tx_antenna_count, ...
+                       rx_antenna_count, apep, mcs);
+
+normalized_cfo = satelliteDopplerShift / wifi_be_subcarrier_spacing;
+
+disp("Channel Info: ")
+disp(chInfo)
+disp("Satellite Doppler Shift: " + satelliteDopplerShift)
+disp("Normalized CFO: " + normalized_cfo)
+
+
+snrs = (0:1:40);
+packets_per_snr = 250;
+maxNumErrors = 10;
+
+errorCounts = zeros(size(snrs));
+for snrIndex = 1:length(snrs)
+    errorCounts(snrIndex) = simulateTransmission(cfgEHT, channel, snrs(snrIndex), packets_per_snr, maxNumErrors, simParameters, chanBW, snrIndex);
+end
+
+errorRate = errorCounts / packets_per_snr;
+
+disp("ErrorRatePerSNR: " + errorRate);

lab_4/link_level_measurements.md

@@ -0,0 +1,4 @@
+> This PDF will be a bit more 'well defined'
+
+## Task1
+For the baseline configuration with f_c = 2.4GHz, LEO altitude 600km, elevation angle 50° (like example), and static receiver, the computed satellite Doppler shift is approximately 35.56kHz. With the IEEE 802.11be subcarrier spacing of 78.125kHz, this corresponds to a normalized CFO of \epsilon \approx 0.455. Therefore, the Doppler shift is below one subcarrier spacing but still represents a significant fraction of the OFDM subcarrier spacing.

lab_4/normalized_carrier_frequency_offset.m

@@ -0,0 +1,3 @@
+function result = normalized_carrier_frequency_offset(freq_doppler, delta_freq_subcarrier)
+    result = freq_doppler / delta_freq_subcarrier;
+end

lab_4/simulateTransmission.m

@@ -0,0 +1,72 @@
+function numPacketErrors = simulateTransmission(cfgEHT, channel, snr, packets, maxNumErrors, simParameters, chanBW, substreamIndex)
+    numPacketErrors = 0;
+
+    ofdmInfo = wlanEHTOFDMInfo('EHT-Data', cfgEHT);
+    ind = wlanFieldIndices(cfgEHT);
+
+    if nargin < 8
+        substreamIndex = 1;
+    end
+
+    stream = RandStream('combRecursive', Seed=simParameters.Seed);
+    stream.Substream = substreamIndex;
+    RandStream.setGlobalStream(stream);
+
+    snrVal = convertSNR(snr, "snrsc", "snr", FFTLength=ofdmInfo.FFTLength, NumActiveSubcarriers=ofdmInfo.NumTones);
+
+    for packetIdx = 1:packets
+        if numPacketErrors >= maxNumErrors
+            break;
+        end
+
+        txPSDU = randi([0 1], psduLength(cfgEHT) * 8, 1);
+        tx = wlanWaveformGenerator(txPSDU, cfgEHT);
+
+        txPad = [tx; zeros(50, cfgEHT.NumTransmitAntennas)];
+
+        reset(channel);
+        rx = awgn(channel(txPad), snrVal);
+
+        coarsePacketOffset = wlanPacketDetect(rx, chanBW);
+        if isempty(coarsePacketOffset)
+            numPacketErrors = numPacketErrors + 1;
+            continue;
+        end
+
+        lstf = rx(coarsePacketOffset + (ind.LSTF(1) : ind.LSTF(2)), :);
+        coarseFrequencyOffset = wlanCoarseCFOEstimate(lstf, chanBW);
+        rx = frequencyOffset(rx, simParameters.SampleRate, -coarseFrequencyOffset);
+
+        nonhtfields = rx(coarsePacketOffset + (ind.LSTF(1) : ind.LSTF(2)), :);
+        finePacketOffset = wlanSymbolTimingEstimate(nonhtfields, chanBW);
+
+        packetOffset = coarsePacketOffset + finePacketOffset;
+
+        if packetOffset > 50
+            numPacketErrors = numPacketErrors + 1;
+            continue;
+        end
+
+        rxLLTF = rx(packetOffset + (ind.LLTF(1) : ind.LLTF(2)), :);
+        fineFrequencyOffset = wlanFineCFOEstimate(rxLLTF, chanBW);
+        rx = frequencyOffset(rx, simParameters.SampleRate, -fineFrequencyOffset);
+
+        rxHELTF = rx(packetOffset + (ind.EHTLTF(1) : ind.EHTLTF(2)), :);
+        heltfDemod = wlanEHTDemodulate(rxHELTF, "EHT-LTF", cfgEHT);
+        [chanEstimate, pilotEstimate] = wlanEHTLTFChannelEstimate(heltfDemod, cfgEHT);
+
+        rxData = rx(packetOffset + (ind.EHTData(1) : ind.EHTData(2)), :);
+        demodSym = wlanEHTDemodulate(rxData, "EHT-Data", cfgEHT);
+
+        nVarEst = wlanEHTDataNoiseEstimate(demodSym(ofdmInfo.PilotIndices, :, :),pilotEstimate, cfgEHT);
+
+        demodDataSym = demodSym(ofdmInfo.DataIndices, :, :);
+        chanEstimateData = chanEstimate(ofdmInfo.DataIndices, :, :);
+
+        [eqSym, csi] = wlanEHTEqualize(demodDataSym, chanEstimateData, nVarEst, cfgEHT, 'EHT-Data');
+
+        rxPSDU = wlanEHTDataBitRecover(eqSym, nVarEst, csi, cfgEHT);
+
+        numPacketErrors = numPacketErrors + any(biterr(txPSDU, rxPSDU));
+    end
+end