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Impl task1 some part of task2

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ti_mo
2026-05-19 21:56:06 +02:00
parent fca31532d1
commit 1561016689
8 changed files with 849 additions and 187 deletions
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lab_3/from_matlab_example/hWLANPacketDetector.m
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classdef hWLANPacketDetector < handle & comm.internal.ConfigBase
%hWLANPacketDetector OFDM packet detection using the L-STF
%
% WPD = hWLANPacketDetector(X,CBW) creates an hWLANPacketDetector object,
% WPD, that sets the Waveform property to X and ChannelBandwidth to CBW.
%
% WPD = hWLANPacketDetector(...,Name,Value) creates an
% hWLANPacketDetector object, WPD, with the specified property Name set
% to the specified Value. You can specify additional name-value pair
% arguments in any order as (Name1,Value1,...,NameN,ValueN).
%
% hWLANPacketDetector methods:
%
% findPacketStart - Returns the offset to the start of a detected
% packet in Waveform
%
% hWLANPacketDetector properties:
%
% Waveform - A time-domain signal specified as a Ns-by-Nr
% matrix of real or complex float values where Ns
% represents the number of time domain samples and
% Nr represents the number of receive antennas.
% ChannelBandwidth - A text scalar describing the channel bandwidth of
% WAVEFORM. The value must be 'CBW5', 'CBW10',
% 'CBW20', 'CBW40', 'CBW80', 'CBW160', or 'CBW320'.
% OversamplingFactor - The oversampling factor of WAVEFORM. The value
% must be greater than or equal to 1. The default is
% 1.
% Threshold - The threshold which the decision statistic must
% meet or exceed to detect a packet in WAVEFORM when
% calling FINDPACKETSTART. The value must be a real
% scalar that is greater than 0 and less than or
% equal to 1. The default is 0.5.
% SearchOffset - The index from which FINDPACKETSTART looks for a
% packet. The value must be a real scalar integer
% that is greater than or equal to 0 and less than
% Ns in WAVEFORM. The default is 0.
%
%
% % Example 1:
% % Detect a received 802.11a packet
% cfgNonHT = wlanNonHTConfig; % Create packet configuration
%
% % Generate transmit waveform
% txWaveform = wlanWaveformGenerator([1;0;0;1],cfgNonHT, ...
% 'WindowTransitionTime',0);
%
% % Delay the signal by appending zeros at the start
% rxWaveform = [zeros(20,1);txWaveform];
%
% wpd = hWLANPacketDetector(rxWaveform,cfgNonHT.ChannelBandwidth);
% wpd.SearchOffset = 5;
% wpd.Threshold = 0.99;
%
% startOffset = findPacketStart(wpd);
%
% disp("Packet start offset: " + startOffset)
% Copyright 2024 The MathWorks, Inc.
properties
Waveform {mustBeFloat,mustBeFinite} = [];
ChannelBandwidth {mustBeTextScalar} = 'CBW20';
OversamplingFactor (1,1) {mustBeNumeric, mustBeFinite, mustBeGreaterThanOrEqual(OversamplingFactor, 1)} = 1;
Threshold (1,1) {mustBeFloat, mustBeReal, mustBeInRange(Threshold,0,1,'exclude-lower')} = 0.5;
SearchOffset (1,1) {mustBeNumeric,mustBeInteger,mustBeNonnegative} = 0;
end
properties(Access=private)
UpdateDecisionStatistic = true;
UpdatePacketOffsets = true;
FoundOffsets;
DecisionStatistic;
DetectedColumnIndicies;
end
methods
function obj = hWLANPacketDetector(wav,cbw,opts)
arguments
wav;
cbw;
opts.Threshold
opts.OversamplingFactor
opts.SearchOffset
end
nvpairs = [{'Waveform' wav 'ChannelBandwidth' cbw} namedargs2cell(opts)];
obj@comm.internal.ConfigBase(nvpairs{:});
end
function [startOffset,M] = findPacketStart(obj)
%findPacketStart Return the offset of a detected packet
%
% [STARTOFFSET,M] = findPacketStart(OBJ) returns the index of a
% detected packet in WAVEFORM. The index returned is the next
% closest index to SEARCHOFFSET. If no packet is detected an empty
% value is returned.
%
% OBJ is a hWLANPacketDetector object.
%
% STARTOFFSET is an integer scalar indicating the location of the
% start of a detected packet.
%
% M is a real vector of size N-by-1, representing the decision
% statistics based on auto-correlation of WAVEFORM. The
% length of N depends on index of a successful detection of a
% packet.
if isempty(obj.Waveform)
startOffset = [];
M = [];
return;
end
cbw = obj.ChannelBandwidth;
[fftLen,nsc] = wlan.internal.cbw2nfft(cbw);
osf = obj.OversamplingFactor;
wlan.internal.validateOFDMOSF(osf, fftLen, 0); % Validate OSF
Td = 0.8e-6; % Time period of a short training symbol for 20MHz
symbolLength = Td*osf*nsc*20e6;
lenLSTF = symbolLength*10; % Length of 10 L-STF symbols
lenHalfLSTF = lenLSTF/2; % Length of 5 L-STF symbols
if obj.UpdateDecisionStatistic
inpLength = size(obj.Waveform,1);
% Append zeros to make the input equal to multiple of L-STF/2
if inpLength<=lenHalfLSTF
numPadSamples = lenLSTF - inpLength;
else
numPadSamples = lenHalfLSTF*ceil(inpLength/lenHalfLSTF) - inpLength;
end
padSamples = zeros(numPadSamples,size(obj.Waveform,2),'like',obj.Waveform);
% Process the input waveform in blocks of L-STF length. The processing
% blocks are offset by half the L-STF length.
numBlocks = (inpLength + numPadSamples)/lenHalfLSTF;
searchBuffer = reshape([obj.Waveform;padSamples],lenHalfLSTF,numBlocks,size(obj.Waveform,2));
searchBuffer = [searchBuffer(:,1:end-1,:);searchBuffer(:,2:end,:)];
[obj.FoundOffsets,obj.DecisionStatistic,obj.DetectedColumnIndicies] = ...
wlan.internal.detectPackets(searchBuffer,symbolLength, ...
lenLSTF,obj.Threshold);
obj.UpdateDecisionStatistic = false;
obj.UpdatePacketOffsets = false;
elseif obj.UpdatePacketOffsets
% obj.Threshold was updated so update the offsets
[obj.FoundOffsets,obj.DetectedColumnIndicies] = ...
getPacketOffsets(obj.DecisionStatistic,symbolLength, ...
lenLSTF,obj.Threshold);
obj.UpdatePacketOffsets = false;
end
idx = find(obj.FoundOffsets >= obj.SearchOffset,1);
startOffset = obj.FoundOffsets(idx);
if isempty(idx)
endIdx = size(obj.DecisionStatistic,2);
else
endIdx = obj.DetectedColumnIndicies(idx);
end
M = double([reshape(obj.DecisionStatistic(1:lenHalfLSTF,1:endIdx-1),[],1); ...
reshape(obj.DecisionStatistic(:,endIdx),[],1)]);
end % function findPacketStart
% Setters
function set.Waveform(obj,value)
if ~isequal(obj.Waveform,value)
obj.Waveform = value;
obj.UpdateDecisionStatistic = true; %#ok<*MCSUP>
end
end
function set.ChannelBandwidth(obj,value)
if ~strcmpi(obj.ChannelBandwidth,value)
obj.ChannelBandwidth = wlan.internal.validateParam('NONHTEHTCHANBW', value, mfilename);
obj.UpdateDecisionStatistic = true;
end
end
function set.OversamplingFactor(obj,value)
if ~isequal(obj.OversamplingFactor,value)
obj.OversamplingFactor = value;
obj.UpdateDecisionStatistic = true;
end
end
function set.Threshold(obj,value)
if ~isequal(obj.Threshold,value)
obj.Threshold = value;
obj.UpdatePacketOffsets = true;
end
end
function set.SearchOffset(obj,value)
coder.internal.errorIf(~isempty(obj.Waveform) && value>size(obj.Waveform, 1)-1, 'wlan:shared:InvalidOffsetValue')
obj.SearchOffset = value;
end
end
end
function [packetStarts,colIdxs] = getPacketOffsets(mn,symbolLength,lenLSTF,threshold)
% mn: Decision statistic
% threshold: Decision threshold as specified by user
N = mn > threshold;
colDesc = sum(N) >= symbolLength*1.5;
N(:,~colDesc) = false;
colIdxs = find(colDesc);
% Create a matrix of indicies where each column has the value 1:corrLen
% then extract indices based on N and desc and calculate all possible
% packet start locations
corrLen = lenLSTF - (symbolLength*2) + 1;
idxs = repmat((1:corrLen)',1,size(N,2));
idxs(~N) = NaN;
idxs = idxs(:,colDesc);
packetStarts = min(idxs) + (colIdxs-1)*lenLSTF/2 - 1;
% Check relative distances between peaks for all detected packets
if ~isempty(packetStarts)
packetStarts = arrayfun(@(x)checkRelativeDist(packetStarts(x),idxs(:,x),symbolLength),1:length(packetStarts));
end
% Extract non-NaN values
colIdxs = colIdxs(~isnan(packetStarts));
packetStarts = packetStarts(~isnan(packetStarts));
end
function pS = checkRelativeDist(pS,idxs,symbolLength)
% Check the relative distance between peaks relative to the first peak. If
% this exceed three times the symbol length then the packet is not
% detected.
nonan = idxs(~isnan(idxs));
if any(nonan(2:symbolLength) - nonan(1)>symbolLength*3)
pS = NaN;
end
end
lab_3/from_matlab_example/recoverOFDMBits.m
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function [decBits,decParams,searchOffset,res] = recoverOFDMBits(rx,searchOffset)
%recoverOFDMBits Performs non-HT OFDM signal recovery
% [DECBITS,DECPARAMS,SEARCHOFFSET,RES] = recoverOFDMBits(RX,SEARCHOFFSET)
% detects a OFDM packet and performs analysis of the non-HT preamble,
% L-SIG, data fields.
%
% DECBITS is a vector containing the decoded bits in a non-HT packet.
%
% DECPARAMS is a structure containing the decoded signal parameters.
%
% SEARCHOFFSET is the offset from the start of RX in samples to the
% next point from which to search for a packet.
%
% RES is a structure containing signal analysis.
%
% RX is the received time-domain waveform. It is a Ns-by-Nr matrix of
% real or complex values, where Ns represents the number of time-domain
% samples in the waveform, and Nr represents the number of receive
% antennas.
% Copyright 2024 The MathWorks, Inc.
% recoverPreamble detects a packet and performs analysis of the non-HT preamble.
decBits = [];
decParams = struct;
decParams.modulation = nan;
decParams.codeRate = nan;
decParams.MCS = nan;
decParams.PSDULength = nan;
decParams.failCheck = nan;
cbw = "CBW20";
cfg = wlanNonHTConfig(ChannelBandwidth=cbw);
ind = wlanFieldIndices(cfg);
sampleRate = 20e6;
maxNonHTPacketTime = 5.484e-3;
maxNonHTPacketSamples = maxNonHTPacketTime*sampleRate;
[preambleStatus,res] = recoverPreamble(rx,cbw,searchOffset);
if matches(preambleStatus,"No packet detected")
searchOffset = length(rx);
return;
end
% Retrieve synchronized data and scale it with LSTF power as done
% in the recoverPreamble function.
if maxNonHTPacketSamples <= (length(rx) - res.PacketOffset)
endIdx = maxNonHTPacketSamples + res.PacketOffset;
else
endIdx = length(rx);
end
syncData = rx(res.PacketOffset+1:endIdx)./sqrt(res.LSTFPower);
syncData = frequencyOffset(syncData,sampleRate,-res.CFOEstimate);
% Need only 4 OFDM symbols (LSIG + 3 more symbols) following LLTF
% for format detection
fmtDetect = syncData(ind.LSIG(1):(ind.LSIG(2)+4e-6*sampleRate*3));
[LSIGBits, failcheck] = wlanLSIGRecover(fmtDetect(1:4e-6*sampleRate*1), ...
res.ChanEstNonHT,res.NoiseEstNonHT,cbw);
decParams.failCheck = failcheck;
if ~failcheck
format = wlanFormatDetect(fmtDetect,res.ChanEstNonHT,res.NoiseEstNonHT,cbw);
if matches(format,"Non-HT")
% Extract MCS from first 3 bits of L-SIG.
rate = double(bit2int(LSIGBits(1:3),3));
if rate <= 1
cfg.MCS = rate + 6;
else
cfg.MCS = mod(rate,6);
end
[modulation,coderate] = getRateInfo(cfg.MCS);
decParams.modulation = modulation;
decParams.coderate = coderate;
decParams.MCS = cfg.MCS;
% Determine PSDU length from L-SIG.
cfg.PSDULength = double(bit2int(LSIGBits(6:17),12,0));
decParams.PSDULength = cfg.PSDULength;
ind.NonHTData = wlanFieldIndices(cfg,"NonHT-Data");
if double(ind.NonHTData(2)-ind.NonHTData(1))> ...
length(syncData(ind.NonHTData(1):end))
% Exit function as full packet not captured.
searchOffset = length(rx);
return;
end
nonHTData = syncData(ind.NonHTData(1):ind.NonHTData(2));
decBits = wlanNonHTDataRecover(nonHTData,res.ChanEstNonHT, ...
res.NoiseEstNonHT,cfg);
% Shift packet search offset for next iteration of while loop.
searchOffset = res.PacketOffset + double(ind.NonHTData(2));
else
% Packet is NOT non-HT; shift packet search offset by 10 OFDM symbols (minimum
% packet length of non-HT) for next iteration of while loop.
searchOffset = res.PacketOffset + 4e-6*sampleRate*10;
end
else
% L-SIG recovery failed; shift packet search offset by 10 OFDM symbols (minimum
% packet length of non-HT) for next iteration of while loop.
searchOffset = res.PacketOffset + 4e-6*sampleRate*10;
end
end
function [modulation,coderate] = getRateInfo(mcs)
% GETRATEINFO returns the modulation scheme as a character array and the
% code rate of a packet given a scalar integer representing the modulation
% coding scheme
switch mcs
case 0 % BPSK
modulation = 'BPSK';
coderate = '1/2';
case 1 % BPSK
modulation = 'BPSK';
coderate = '3/4';
case 2 % QPSK
modulation = 'QPSK';
coderate = '1/2';
case 3 % QPSK
modulation = 'QPSK';
coderate = '3/4';
case 4 % 16QAM
modulation = '16QAM';
coderate = '1/2';
case 5 % 16QAM
modulation = '16QAM';
coderate = '3/4';
case 6 % 64QAM
modulation = '64QAM';
coderate = '2/3';
otherwise % 64QAM
modulation = '64QAM';
coderate = '3/4';
end
end
lab_3/from_matlab_example/recoverPreamble.m
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function [status,res] = recoverPreamble(rx,chanBW,searchOffset,varargin)
%recoverPreamble Preamble signal recovery
% [STATUS,RES] = recoverPreamble(RX,CHANBW,SEARCHOFFSET) detects a packet
% and performs analysis of the non-HT preamble.
%
% STATUS is the processing status and is either 'Success' or 'No packet
% detected'.
%
% RES is a structure containing signal analysis.
%
% RX is the received time-domain waveform. It is a Ns-by-Nr matrix of
% real or complex values, where Ns represents the number of time-domain
% samples in the waveform, and Nr represents the number of receive
% antennas.
%
% CHANBW is the channel bandwidth and must be 'CBW20', 'CBW40', 'CBW80',
% 'CBW160', or 'CBW320'.
%
% SEARCHOFFSET is the offset from the start of RX in samples to begin
% searching for a packet.
%
% [STATUS,RES] = recoverPreamble(...,CFGALG) optionally allows
% algorithm options to be used as specified in the structure CFGALG.
% Copyright 2019-2025 The MathWorks, Inc.
persistent wpd
cfgAlg = algorithmConfig(varargin{:});
if isempty(wpd)
wpd = hWLANPacketDetector(rx,chanBW);
else
wpd.Waveform = rx;
wpd.ChannelBandwidth = chanBW;
end
wpd.Threshold = cfgAlg.PacketDetectionThreshold;
cfgBase = wlanEHTMUConfig(chanBW);
index = wlanFieldIndices(cfgBase);
sr = wlanSampleRate(cfgBase);
if cfgAlg.EnergyDetection
movrms = dsp.MovingRMS;
movrms.WindowLength = cfgAlg.EnergyDetectionWindow;
threshold = 10^(cfgAlg.EnergyDetectionThreshold/20);
end
% Minimum packet length is L-STF, L-LTF, L-SIG + 1 Data symbol
lstfLen = double(index.LSTF(2)); % Number of samples in L-STF
minPktLen = lstfLen*3;
% Minimum number of samples to skip before searching for next packet
minAdvLen = lstfLen*4/10;
rxWaveformLen = size(rx,1);
% Do not search for packets if waveform is too short
if (searchOffset+minPktLen)>rxWaveformLen
status = 'No packet detected';
res = defaultResults();
return
end
% Initialize incase no packets detected
packetOffset = nan;
cfoEstimate = nan;
lstfPower = nan;
lltfPower = nan;
chanEstNonHT = [];
noiseEstNonHT = nan;
lltfSNREst = nan;
status = 'No packet detected';
wpd.SearchOffset = searchOffset;
while (wpd.SearchOffset+minPktLen)<=rxWaveformLen
% Detect a packet
if cfgAlg.SkipPacketDetection
packetOffset = 0;
else
packetOffset = findPacketStart(wpd);
end
% Adjust packet offset
if isempty(packetOffset) || (packetOffset<0) || (packetOffset+double(index.LSIG(2))>rxWaveformLen)
status = 'No packet detected';
break
end
if cfgAlg.EnergyDetection
% Run RMS over part of the waveform of interest - where we expect a ramp up
reset(movrms)
idx = (packetOffset+(-movrms.WindowLength+1:(2*movrms.WindowLength)));
idx(idx<1) = []; % In case waveform detected as start
rxRMS = movrms(rx(idx,:));
if all(mean(rxRMS(movrms.WindowLength+1:end,:),2)<threshold)
% If energy detected is not high enough continue searching
wpd.SearchOffset = packetOffset+minAdvLen;
continue;
end
end
% Coarse Frequency Offset Estimation
% Extract non-HT fields and perform coarse frequency offset correction
% to allow for reliable symbol timing
preamble = rx(packetOffset+(index.LSTF(1):index.LSIG(2)),:);
coarseFreqOffset = wlanCoarseCFOEstimate(preamble,chanBW);
preamble = frequencyOffset(preamble,sr,-coarseFreqOffset);
% Timing Synchronization
% Symbol timing synchronization: 4 OFDM symbols to search for L-LTF
if cfgAlg.SkipPacketDetection
lltfStartOffset = 0;
else
lltfStartOffset = wlanSymbolTimingEstimate(preamble,chanBW);
end
% If packet offset is significantly less than search offset then
% likely a false detection
if (packetOffset+lltfStartOffset)<=(wpd.SearchOffset-minAdvLen)
% Skip 4/10 of L-STF length of samples and continue searching
wpd.SearchOffset = packetOffset+minAdvLen;
continue
end
% End search if min packet length is outside of waveform
packetOffset = packetOffset+lltfStartOffset;
if (packetOffset+minPktLen)>rxWaveformLen
break
end
% Force packet offset not to be 0 to prevent hard errors
packetOffset = max(packetOffset,0);
% Extract preamble with fine timing sync
preamble = rx(packetOffset+(index.LSTF(1):index.LLTF(2)),:);
preamble = frequencyOffset(preamble,sr,-coarseFreqOffset);
% Fine Frequency Offset Estimation
% Perform fine frequency offset correction on the synchronized and
% coarse corrected Non-HT fields
lltf = preamble(index.LLTF(1):index.LLTF(2),:); % Extract L-LTF
fineFreqOffset = wlanFineCFOEstimate(lltf,chanBW);
preamble = frequencyOffset(preamble,sr,-fineFreqOffset);
cfoEstimate = coarseFreqOffset+fineFreqOffset; % Total CFO
% AGC
% Scale preamble by rx power before performing channel estimation
lstf = preamble(index.LSTF(1):index.LSTF(2),:);
lstfPower = mean(lstf(:).*conj(lstf(:)));
preamble = preamble/sqrt(lstfPower);
% Channel and noise estimation using L-LTF
lltf = preamble(index.LLTF(1):index.LLTF(2),:);
demodLLTF = wlanLLTFDemodulate(lltf,chanBW);
chanEstNonHT = wlanLLTFChannelEstimate(demodLLTF,chanBW,cfgAlg.LLTFChannelEstimateSmoothingSpan);
noiseEstNonHT = wlanLLTFNoiseEstimate(demodLLTF);
lltfPower = mean(lltf(:).*conj(lltf(:)))*lstfPower; % Subtract AGC scaling
% Test if carrier lost (L-LTF power substantially less than L-STF)
if cfgAlg.DetectCarrierLoss
if lltfPower<(0.25*lstfPower)
% Skip 4/10 of L-STF length of samples and continue searching
wpd.SearchOffset = packetOffset+minAdvLen;
continue
end
end
% Test large difference in energy between L-STF and L-LTF which is suspicious
if cfgAlg.DetectPowerFluctuation
if lstfPower<(0.125*lltfPower)
% Skip 4/10 of L-STF length of samples and continue searching
wpd.SearchOffset = packetOffset+minAdvLen;
continue
end
end
% Estimate SNR from L-LTF
lltfSNREst = 10*log10(mean(abs(chanEstNonHT(:)).^2)/noiseEstNonHT);
% Test if SNR it too low or isnan (when channel and noise estimate are 0)
if cfgAlg.DetectLLTFSNRTooLow
if isnan(lltfSNREst) || lltfSNREst<cfgAlg.LLTFSNRDetectionThreshold
% Skip L-STF length of samples and continue searching
wpd.SearchOffset = packetOffset+minAdvLen;
continue
end
end
% Packet detected
status = 'Success';
break
end
if strcmp(status,'No packet detected')
res = defaultResults();
wpd = [];
else
res = struct;
res.PacketOffset = packetOffset;
res.CFOEstimate = cfoEstimate;
res.LSTFPower = lstfPower;
res.LLTFPower = lltfPower;
res.ChanEstNonHT = chanEstNonHT;
res.NoiseEstNonHT = noiseEstNonHT;
res.LLTFSNR = lltfSNREst;
res.DemodLLTF = demodLLTF;
end
end
function res = defaultResults()
res = struct;
res.PacketOffset = nan;
res.CFOEstimate = nan;
res.LSTFPower = nan;
res.LLTFPower = nan;
res.ChanEstNonHT = nan;
res.NoiseEstNonHT = nan;
res.LLTFSNR = nan;
res.DemodLLTF = nan;
end
function cfg = algorithmConfig(varargin)
if nargin>0
cfg = varargin{1};
if ~isfield(cfg,'DetectCarrierLoss')
cfg.DetectCarrierLoss = true;
end
if ~isfield(cfg,'DetectPowerFluctuation')
cfg.DetectPowerFluctuation = true;
end
if ~isfield(cfg,'DetectLLTFSNRTooLow')
cfg.DetectLLTFSNRTooLow = true;
end
if ~isfield(cfg,'SkipPacketDetection')
cfg.SkipPacketDetection = false;
end
else
cfg = struct;
cfg.PacketDetectionThreshold = 0.5;
cfg.EnergyDetection = false;
cfg.EnergyDetectionThreshold = 0;
cfg.EnergyDetectionWindow = 20;
cfg.LLTFChannelEstimateSmoothingSpan = 1;
cfg.DetectCarrierLoss = true;
cfg.DetectPowerFluctuation = true;
cfg.DetectLLTFSNRTooLow = true;
cfg.LLTFSNRDetectionThreshold = 0;
cfg.SkipPacketDetection = false;
end
end
lab_3/lab_3.m
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calculations_only = true;
task1; task1;
task2;
lab_3/task1.asv
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@@ -1,116 +0,0 @@
trace1 = load("traces/2412mhz.mat", "iq");
trace2 = load("traces/2432mhz.mat", "iq");
trace3 = load("traces/2452mhz.mat", "iq");
trace4 = load("traces/2472mhz.mat", "iq");
window = 512;
overlap = 64;
fft_precision = 2048;
sample_rate = 20e6; % 20 MS/s
% 1.
duration1 = length(trace1.iq) / sample_rate;
duration2 = length(trace2.iq) / sample_rate;
duration3 = length(trace3.iq) / sample_rate;
duration4 = length(trace4.iq) / sample_rate;
% 2.
% get all four plot values
[~,F1,T1,P1] = spectrogram(trace1.iq, window, overlap, fft_precision, sample_rate, "centered", "psd");
[~,F2,T2,P2] = spectrogram(trace2.iq, window, overlap, fft_precision, sample_rate, "centered", "psd");
[~,F3,T3,P3] = spectrogram(trace3.iq, window, overlap, fft_precision, sample_rate, "centered", "psd");
[~,F4,T4,P4] = spectrogram(trace4.iq, window, overlap, fft_precision, sample_rate, "centered", "psd");
% begin calibrated color scale
P1_dB = 10 * log10(P1);
P2_dB = 10 * log10(P2);
P3_dB = 10 * log10(P3);
P4_dB = 10 * log10(P4);
all_P_dB = [P1_dB(:); P2_dB(:); P3_dB(:); P4_dB(:)];
p_dB_min = min(all_P_dB) - 20;
p_dB_max = max(all_P_dB) + 20;
% end power calibrated color scale
% plot all figures like example shows
figure(1);
imagesc(T1, F1, P1_dB);
axis ij;
xlabel("Time [s]");
ylabel("Freq. [Hz]");
title("Spectrogram Trace 1");
cb = colorbar;
ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]);
xlim([0 0.05]);
figure(2);
imagesc(T2, F2, P2_dB);
axis ij;
xlabel("Time [s]");
ylabel("Freq. [Hz]");
title("Spectrogram Trace 2");
cb = colorbar;
ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]);
xlim([0 0.05]);
figure(3);
imagesc(T3, F3, P3_dB);
axis ij;
xlabel("Time [s]");
ylabel("Freq. [Hz]");
title("Spectrogram Trace 3");
cb = colorbar;
ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]);
xlim([0 0.05]);
figure(4);
imagesc(T4, F4, P4_dB);
axis ij;
xlabel("Time [s]");
ylabel("Freq. [Hz]");
title("Spectrogram Trace 4");
cb = colorbar;
ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]);
xlim([0 0.05]);
% 3.
noise_floor1 = prctile(P1_dB(:), 10);
noise_floor2 = prctile(P2_dB(:), 10);
noise_floor3 = prctile(P3_dB(:), 10);
noise_floor4 = prctile(P4_dB(:), 10);
% 4.
occupancy1 = sum(P1_dB(:) > noise_floor1 + 10) / numel(P1_dB) * 100;
occupancy2 = sum(P2_dB(:) > noise_floor2 + 10) / numel(P2_dB) * 100;
occupancy3 = sum(P3_dB(:) > noise_floor3 + 10) / numel(P3_dB) * 100;
occupancy4 = sum(P4_dB(:) > noise_floor4 + 10) / numel(P4_dB) * 100;
occupancies = [occupancy1 occupancy2 occupancy3 occupancy4];
channels = [1 5 9 13];
[occupancy_max, max_idx] = max(occupancies);
busiest_channel = channels(max_idx);
disp("Results:" + newline)
disp("-- Trace duration ---")
disp("Channel 1 duration: " + duration1 + "s")
disp("Channel 5 duration: " + duration2 + "s")
disp("Channel 9 duration: " + duration3 + "s")
disp("Channel 13 duration: " + duration4 + "s" + newline)
disp("--- Noise floor ---")
disp("Destinct:")
disp("Channel 1 noise floor: " + noise_floor1 + "dB")
disp("Channel 5 noise floor: " + noise_floor2 + "dB")
disp("Channel 9 noise floor: " + noise_floor3 + "dB")
disp("Channel 13 noise floor: " + noise_floor4 + "dB" )
disp(newline)
disp("Combined:")
disp("Channel all noise floor: " + sum([noise_floor1 noise_floor2, noise_floor3, noise_floor4]) / 4 + "dB")
lab_3/task1.m
+72 -67
View File
@@ -17,10 +17,10 @@ duration4 = length(trace4.iq) / sample_rate;
% 2. % 2.
% get all four plot values % get all four plot values
[~,F1,T1,P1] = spectrogram(trace1.iq, window, overlap, fft_precision, sample_rate, "centered", "psd"); [~,F1,T1,P1] = spectrogram(trace1.iq, window, overlap, fft_precision, sample_rate, "centered", "power");
[~,F2,T2,P2] = spectrogram(trace2.iq, window, overlap, fft_precision, sample_rate, "centered", "psd"); [~,F2,T2,P2] = spectrogram(trace2.iq, window, overlap, fft_precision, sample_rate, "centered", "power");
[~,F3,T3,P3] = spectrogram(trace3.iq, window, overlap, fft_precision, sample_rate, "centered", "psd"); [~,F3,T3,P3] = spectrogram(trace3.iq, window, overlap, fft_precision, sample_rate, "centered", "power");
[~,F4,T4,P4] = spectrogram(trace4.iq, window, overlap, fft_precision, sample_rate, "centered", "psd"); [~,F4,T4,P4] = spectrogram(trace4.iq, window, overlap, fft_precision, sample_rate, "centered", "power");
% begin calibrated color scale % begin calibrated color scale
P1_dB = 10 * log10(P1); P1_dB = 10 * log10(P1);
@@ -30,54 +30,57 @@ P4_dB = 10 * log10(P4);
all_P_dB = [P1_dB(:); P2_dB(:); P3_dB(:); P4_dB(:)]; all_P_dB = [P1_dB(:); P2_dB(:); P3_dB(:); P4_dB(:)];
p_dB_min = min(all_P_dB) - 20; % -50 to +50 so its like the example fig
p_dB_max = max(all_P_dB) + 20; p_dB_min = min(all_P_dB) - 50;
p_dB_max = max(all_P_dB) + 50;
% end power calibrated color scale % end power calibrated color scale
% plot all figures like example shows if ~calculations_only
figure(1); % plot all figures like example shows
imagesc(T1, F1, P1_dB); figure(1);
axis ij; imagesc(T1, F1, P1_dB);
xlabel("Time [s]"); axis ij;
ylabel("Freq. [Hz]"); xlabel("Time [s]");
title("Spectrogram Trace 1"); ylabel("Freq. [Hz]");
cb = colorbar; title("Spectrogram Trace 1");
ylabel(cb, "Power [dB]"); cb = colorbar;
clim([p_dB_min p_dB_max]); ylabel(cb, "Power [dB]");
xlim([0 0.05]); clim([p_dB_min p_dB_max]);
xlim([0 0.05]);
figure(2); figure(2);
imagesc(T2, F2, P2_dB); imagesc(T2, F2, P2_dB);
axis ij; axis ij;
xlabel("Time [s]"); xlabel("Time [s]");
ylabel("Freq. [Hz]"); ylabel("Freq. [Hz]");
title("Spectrogram Trace 2"); title("Spectrogram Trace 2");
cb = colorbar; cb = colorbar;
ylabel(cb, "Power [dB]"); ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]); clim([p_dB_min p_dB_max]);
xlim([0 0.05]); xlim([0 0.05]);
figure(3); figure(3);
imagesc(T3, F3, P3_dB); imagesc(T3, F3, P3_dB);
axis ij; axis ij;
xlabel("Time [s]"); xlabel("Time [s]");
ylabel("Freq. [Hz]"); ylabel("Freq. [Hz]");
title("Spectrogram Trace 3"); title("Spectrogram Trace 3");
cb = colorbar; cb = colorbar;
ylabel(cb, "Power [dB]"); ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]); clim([p_dB_min p_dB_max]);
xlim([0 0.05]); xlim([0 0.05]);
figure(4); figure(4);
imagesc(T4, F4, P4_dB); imagesc(T4, F4, P4_dB);
axis ij; axis ij; % flip so its like the example fig
xlabel("Time [s]"); xlabel("Time [s]");
ylabel("Freq. [Hz]"); ylabel("Freq. [Hz]");
title("Spectrogram Trace 4"); title("Spectrogram Trace 4");
cb = colorbar; cb = colorbar;
ylabel(cb, "Power [dB]"); ylabel(cb, "Power [dB]");
clim([p_dB_min p_dB_max]); clim([p_dB_min p_dB_max]);
xlim([0 0.05]); xlim([0 0.05]); % reduce view so its like the example fig
end
% 3. % 3.
noise_floor1 = prctile(P1_dB(:), 10); noise_floor1 = prctile(P1_dB(:), 10);
@@ -99,28 +102,30 @@ channels = [1 5 9 13];
[occupancy_max, max_idx] = max(occupancies); [occupancy_max, max_idx] = max(occupancies);
busiest_channel = channels(max_idx); busiest_channel = channels(max_idx);
disp("Results:" + newline) if ~calculations_only
disp("Results Task 1:" + newline)
disp("-- Trace duration ---") disp("-- Trace duration ---")
disp("Channel 1 duration: " + duration1 + "s") disp("Channel 1 duration: " + duration1 + "s")
disp("Channel 5 duration: " + duration2 + "s") disp("Channel 5 duration: " + duration2 + "s")
disp("Channel 9 duration: " + duration3 + "s") disp("Channel 9 duration: " + duration3 + "s")
disp("Channel 13 duration: " + duration4 + "s" + newline) disp("Channel 13 duration: " + duration4 + "s" + newline)
disp("--- Noise floor ---") disp("--- Noise floor ---")
disp("Distinct:") disp("Distinct:")
disp("Channel 1 noise floor: " + noise_floor1 + "dB") disp("Channel 1 noise floor: " + noise_floor1 + "dB")
disp("Channel 5 noise floor: " + noise_floor2 + "dB") disp("Channel 5 noise floor: " + noise_floor2 + "dB")
disp("Channel 9 noise floor: " + noise_floor3 + "dB") disp("Channel 9 noise floor: " + noise_floor3 + "dB")
disp("Channel 13 noise floor: " + noise_floor4 + "dB" + newline) disp("Channel 13 noise floor: " + noise_floor4 + "dB" + newline)
disp("Combined:") disp("Combined:")
disp("Channel all noise floor: " + noise_floor_avg + "dB" + newline) disp("Channel all noise floor: " + noise_floor_avg + "dB" + newline)
disp("-- Occupancy ---") disp("-- Occupancy ---")
disp("Channel 1 occupancy: " + occupancy1) disp("Channel 1 occupancy: " + occupancy1 + "%")
disp("Channel 5 occupancy: " + occupancy2) disp("Channel 5 occupancy: " + occupancy2 + "%")
disp("Channel 9 occupancy: " + occupancy3) disp("Channel 9 occupancy: " + occupancy3 + "%")
disp("Channel 13 occupancy: " + occupancy4 + newline) disp("Channel 13 occupancy: " + occupancy4 + "%" + newline)
disp("Busiest channel: " + busiest_channel) disp("Busiest channel: " + busiest_channel)
end
lab_3/task2.asv
+29
View File
@@ -0,0 +1,29 @@
channel_bandwidth = "CBW20"; % 20MHz
rxFrame1 = trace1.iq(:);
rxFrame2 = trace2.iq(:);
rxFrame3 = trace3.iq(:);
rxFrame4 = trace4.iq(:);
function beaconFrames = extractBeaconFrames(rxFrame)
beaconFrames = [];
searchOffset = 0;
while searchOffset < length(rxFrame)
[bitsData, decParams, searchOffset, res] = recoverOFDMBits(rxFrame, searchOffset);
if isempty(bitsData)
continue;
end
[cfgMAC, ~, decodeStatus] = wlanMPDUDecode(bitsData, SuppressWarnings=true);
if ~decodeStatus && matches(cfgMAC.FrameType, "Beacon")
disp("Beacon at " + searchOffset);
beaconFrames(end + 1) = cfgMAC;
end
end
end
beaconFrames1 = extractBeaconFrames(rxFrame1);
lab_3/task2.m
+104
View File
@@ -0,0 +1,104 @@
addpath("from_matlab_example");
rxFrame1 = trace1.iq(:);
rxFrame2 = trace2.iq(:);
rxFrame3 = trace3.iq(:);
rxFrame4 = trace4.iq(:);
beaconFrames1 = extractBeaconFrames(rxFrame1);
beaconFrames2 = extractBeaconFrames(rxFrame2);
beaconFrames3 = extractBeaconFrames(rxFrame3);
beaconFrames4 = extractBeaconFrames(rxFrame4);
cfgMAC = beaconFrames1(1).MAC_Config;
mgmt = cfgMAC.ManagementConfig;
disp(mgmt)
properties(mgmt)
printBeaconTable(beaconFrames1);
printBeaconTable(beaconFrames2);
printBeaconTable(beaconFrames3);
printBeaconTable(beaconFrames4);
function beaconFrames = extractBeaconFrames(rxFrame)
beaconFrames = struct( ...
"SSID", {}, ...
"BSSID", {}, ...
"Offset", {}, ...
"MAC_Config", {}, ...
"Bits", {}, ...
"SNR_dB", {} ...
);
channel_bandwidth = "CBW20"; % 20MHz
searchOffset = 0;
index = 1;
while searchOffset < length(rxFrame)
oldOffset = searchOffset;
[bitsData, decParams, searchOffset, res] = recoverOFDMBits(rxFrame, searchOffset);
if searchOffset <= oldOffset
searchOffset = oldOffset + 1;
end
if isempty(bitsData)
continue;
end
[cfgMAC, ~, decodeStatus] = wlanMPDUDecode(bitsData, SuppressWarnings=true);
if ~decodeStatus && matches(cfgMAC.FrameType, "Beacon")
if isempty(cfgMAC.ManagementConfig.SSID)
ssid = "Hidden";
else
ssid = string(cfgMAC.ManagementConfig.SSID);
end
if isfield(res, "PacketOffset")
beaconFrames(index).Offset = res.PacketOffset;
else
beaconFrames(index).Offset = oldOffset;
end
if isfield(res, "LLTFSNR")
beaconFrames(index).SNR_dB = res.LLTFSNR;
else
beaconFrames(index).SNR_dB = NaN;
end
beaconFrames(index).SSID = ssid;
beaconFrames(index).BSSID = string(cfgMAC.Address3);
beaconFrames(index).MAC_Config = cfgMAC;
beaconFrames(index).Bits = bitsData;
index = index + 1;
end
end
end
function printBeaconTable(beaconFrames)
fprintf("\n");
fprintf("%-20s %-18s %-10s %-8s %-8s %-8s %-12s %-8s %-20s\n", ...
"SSID", "BSSID", "Interval", "B. ch.", "Op. ch.", "SNR", "Vendor", "Std.", "Rates");
for i = 1:numel(beaconFrames)
ssid = string(beaconFrames(i).SSID);
bssid = string(beaconFrames(i).BSSID);
interval = string(beaconFrames(i).MAC_Config.ManagementConfig.BeaconInterval);
snr = sprintf("%.1f", beaconFrames(i).SNR_dB);
bch = "-";
opch = "-";
vendor = "-";
std = "-";
rates = "-";
fprintf("%-20s %-18s %-10s %-8s %-8s %-8s %-12s %-8s %-20s\n", ...
ssid, bssid, interval, bch, opch, snr, vendor, std, rates);
end
fprintf("\n");
end