Does the NRHDLDownlinkReceiver work for channel bandwidth = 10mHz and 5mHz? Even though SSB is transmitted in the simulated test cases, none was detected.

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Marvell
Marvell 2024-3-20
The simulated test cases are generated using the 5G Waveform Generator tool, under the downlink FRC category.
The parameters for the simulated waveforms are:
  • Frequency range = FR1
  • MCS = QPSK
  • Subcarrier spacing = 15 kHz
  • Channel bandwidth = 5 MHz/ 10 MHz
  • Duplex mode = FDD
  • Subframes = 10
  • Layers = 1
  • Cell identity = 8
  • RNTI = 1
  • Windowing source = Auto
  • Sample rate source = Auto
According to the resource grid, an SSB has been generated in slot 0
However, when ran through the NRHDLDownlinkReceiver code, which is as such:
%% Generate a Test Waveform
%
% This section shows how to use the MATLAB reference functions to
% search for SSBs in a waveform, demodulate and decode an SSB to recover the MIB, and recover the scheduled SIB1.
%
% Use the |nrhdlexamples.generateRxWaveform| function to generate
% a 5G FR1 waveform containing SSB bursts and the corresponding SIB1 transmissions.
% Change the |simulationCase| to explore different parameter sets. The full
% set of simulation cases is shown.
rxWaveform = rx.waveform;
minChanBW = 5;
Lmax = 16;
rxSampleRate = rx.Fs;
% scsSSB = rx.config.waveform.SSBurst.SubcarrierSpacingCommon;
FoCoarse = 0;
% disp('Test waveform configurations:')
% disp(nrhdlexamples.generateRxWaveform('list'));
%
% rng('default');
%
% simulationCase = "SimCase 1";
% [rxWaveform,ssbPattern,minChanBW,Lmax,rxSampleRate,txMIB,simCase] = nrhdlexamples.generateRxWaveform(simulationCase);
%
% disp("Selected Simulation case:" + newline);
% disp(simCase);
%% Plot the spectogram of the waveform.
% The plot shows a spectogram of the SSBs, CORESET0s, and PDSCH regions
% carrying SIB1. These regions are generated with different power levels.
% The amplitude of each resource element is indicated by its color.
% % Guess scsSSB as 5kHz
% scsSSB = 5;
% figure(1); clf;
% nfft = round(rxSampleRate/(scsSSB*1e3));
% spectrogram(rxWaveform(:,1),ones(nfft,1),0,nfft,'centered',rxSampleRate,'yaxis','MinThreshold',-110);
% title('Spectrogram of the Received Waveform (5 KHz)')
% Guess scsSSB as 15kHz
scsSSB = 15;
figure(2); clf;
nfft = round(rxSampleRate/(scsSSB*1e3));
spectrogram(rxWaveform(:,1),ones(nfft,1),0,nfft,'centered',rxSampleRate,'yaxis','MinThreshold',-110);
title('Spectrogram of the Received Waveform (15 KHz)')
% Guess scsSSB as 30kHz
scsSSB = 30;
figure(3); clf;
nfft = round(rxSampleRate/(scsSSB*1e3));
spectrogram(rxWaveform(:,1),ones(nfft,1),0,nfft,'centered',rxSampleRate,'yaxis','MinThreshold',-110);
title('Spectrogram of the Received Waveform (30 KHz)')
% % Guess scsSSB as 60kHz
% scsSSB = 60;
% figure(4); clf;
% nfft = round(rxSampleRate/(scsSSB*1e3));
% spectrogram(rxWaveform(:,1),ones(nfft,1),0,nfft,'centered',rxSampleRate,'yaxis','MinThreshold',-110);
% title('Spectrogram of the Received Waveform (60 KHz)')
%% Detect SSBs
%
% Use the |nrhdlexamples.ssbDetect| function to find SSBs in the waveform
% by searching for PSS symbols. This example calls the function with a
% coarse carrier frequency offset estimate of zero and a subcarrier spacing
% determined from the SSB pattern of the generated waveform. The function
% corrects the coarse frequency offset and measures the
% residual fine frequency offset of each SSB. Frequency offset input and
% output are given in Hz. The function returns a list of detected PSS
% symbols as a structure array.
% Display the structure array contents by converting it to a table.
scsSSB = 30;
[pssList,diagnostics] = nrhdlexamples.ssbDetect(rxWaveform,FoCoarse,scsSSB);
% Check if any PSS have been detected
if isempty(pssList)
disp('No PSS found during SSB detection.');
return;
end
disp('Detected PSS list:')
disp(struct2table(pssList));
%%
% The |nrhdlexamples.ssbDetect| function also returns a structure containing
% diagnostic signals. Use this output to plot the PSS correlation
% results. Each peak in the correlator output shown corresponds
% to an entry in the PSS list.
figure(2); clf;
nrhdlexamples.plotUtils.PSSCorrelation(diagnostics,'PSS Correlation');
%%
% Use the |nrhdlexamples.ssbDetect| function to OFDM-demodulate one of the SSBs
% and attempt SSS detection. For this operation, call the function with an optional
% 4th argument that specifies the timing offset and NCellID2 of the desired SSB.
% This example chooses the PSS with the highest correlation metric, however
% you can choose any of the detected SSBs.
% Correct the frequency offset by passing in the sum of the coarse and
% fine frequency offset estimates.
[~,maxCorrIdx] = max(vertcat(pssList.pssCorrelation));
chosenPSS = pssList(maxCorrIdx);
disp('Selected PSS:')
disp(struct2table(chosenPSS));
FoFine = chosenPSS.frequencyOffset;
FoEst = FoCoarse + FoFine;
[ssBlockInfo,ssbGrid,diagnostics] = nrhdlexamples.ssbDetect(rxWaveform,FoEst,scsSSB,chosenPSS);
% Check SSB successfully demodulated
if isempty(ssBlockInfo)
disp('Failed to demodulate selected SSB.');
return;
end
%%
% In demodulation mode, the function returns three outputs instead of
% two. The |ssBlockInfo| structure contains further details of the SSB, such as the
% SSS correlation strength and the overall cell ID. The |ssGrid| output is a matrix
% containing the demodulated OFDM symbols.
% Display the SSB info to confirm that the cell ID is
% correctly decoded.
disp('SSB info for demodulated SSB:')
disp(ssBlockInfo);
%%
% Display the resulting SSB resource grid.
figure(3); clf;
imagesc(abs(ssbGrid));
colorbar;
axis xy;
xlabel('OFDM symbol');
ylabel('Subcarrier');
title('SSB Resource Grid');
%%
%
% The |diagnostics| output includes SSS correlation results for all
% 336 possible sequences. Plot the SSS correlation results.
figure(4); clf;
nrhdlexamples.plotUtils.SSSCorrelation(diagnostics,'SSS Correlation')
%% Search for Cells
%
% This section shows how to use the |nrhdlexamples.cellSearch| function
% to search for and demodulate SSBs when the frequency
% offset and subcarrier spacing are not known.
% As described previously, the |nrhdlexamples.cellSearch| function builds on
% the |nrhdlexamples.ssbDetect| function by adding a search controller
% that looks for SSBs at different subcarrier spacings
% and frequency offsets.
%%
% Apply a frequency offset to test the coarse and fine frequency
% recovery functionality.
Fo = 10000;
t = (0:length(rxWaveform)-1).'/61.44e6;
rxWaveform = rxWaveform .* exp(1i*2*pi*Fo*t);
%%
% Define the frequency range endpoints and subcarrier spacing search space
% and call the |nrhdlexamples.cellSearch| function. The function displays
% information on the search progress as it runs.
% The frequency range endpoints must be multiples of half the
% maximum subcarrier spacing.
frequencyRange = [-60 60];
subcarrierSpacings = [15 30];
[ssBlockInfo,ssbGrid] = nrhdlexamples.cellSearch(rxWaveform,frequencyRange,subcarrierSpacings,struct(...
'DisplayPlots',false,...
'DisplayCommandWindowOutput',true));
% Check cell search successfully found and demodulated SSB.
if isempty(ssBlockInfo)
disp('Cell search failed to find or demodulate SSB.');
return;
end
%%
% As shown in the summary, the receiver returned the correct
% subcarrier spacing of 30 kHz, a cell ID of 1, and the measured frequency offset is close to the
% expected value of 10 kHz.
%% Decode SSB
%
% Use the |nrhdlexamples.ssbDecode| function to decode the SSB resource grid and recover the MIB.
% The |nrhdlexamples.ssbDecode| function is based on the BCH decoding
% stages of the <docid:5g_ug#mw_a4db8282-8f25-4802-8b02-548bab69b7dd NR Cell Search and MIB and SIB1 Recovery> example.
[mibInfo,decodeDiags] = nrhdlexamples.ssbDecode(ssbGrid,ssBlockInfo.NCellID,Lmax);
% Check MIB successfully decoded from SSB.
if mibInfo.err
disp('Failed to decode MIB from SSB.');
return;
end
%%
% Plot the correlation peaks for the DMRS search. DMRS search is performed
% to determine ibar_ssb and the SSB index.
figure(5); clf;
plot(0:7,decodeDiags.dmrsCorr);
title('DMRS Search Correlation');
xlabel('ibar ssb');
ylabel('Correlation strength');
%%
% Plot the PBCH QPSK constellation after phase equalization.
figure(6); clf;
plot(decodeDiags.qpskSymb,'o');
xlim(max(abs(real(decodeDiags.qpskSymb))).*[-1.1 1.1]);
ylim(max(abs(imag(decodeDiags.qpskSymb))).*[-1.1 1.1]);
title('PBCH Symbol Constellation');
xlabel('In-phase');
ylabel('Quadrature');
%%
% Initialising the expected MIB
txMIB.NFrame = [];
txMIB.SubcarrierSpacingCommon = rx.config.waveform.SSBurst.SubcarrierSpacingCommon;
txMIB.k_SSB = rx.config.waveform.SSBurst.KSSB;
txMIB.DMRSTypeAPosition = rx.config.waveform.SSBurst.DMRSTypeAPosition;
txMIB.PDCCHConfigSIB1 = rx.config.waveform.SSBurst.PDCCHConfigSIB1;
txMIB.CellBarred = rx.config.waveform.SSBurst.CellBarred;
txMIB.IntraFreqReselection = rx.config.waveform.SSBurst.IntraFreqReselection;
%%
% Display the decoded information and compare the transmitted and received MIB structures.
% These results show that the information was successfully decoded.
disp(['BCH CRC: ' num2str(mibInfo.err) newline]);
disp('Decoded information');
disp(mibInfo);
disp('Decoded MIB');
disp(mibInfo.mib);
disp('Expected MIB');
disp(txMIB);
%%
disp(ssBlockInfo);
No PSS/SSS is detected. Really appreciate your help!

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