NR SSB Beam Sweeping

毫米波频率的支持需要定向链接，这导致在 NR 中初始访问光束管理程序的规范。光束管理是一组第 1 层（物理）和第 2 层（中等访问控制）程序，用于获取和维护一组光束对链（在 gNB 中使用的光束与 UE 使用的光束配对）。下行链路和上行链路传输和接收都适用光束管理程序。这些程序包括：

 rng(211);                           % Set RNG state for repeatability%% Simulation Parameters
%
% Define system parameters for the example. Modify these parameters to
% explore their impact on the system.prm.NCellID = 1;                    % Cell ID
prm.FreqRange = 'FR1';              % Frequency range: 'FR1' or 'FR2'
prm.CenterFreq = 3.5e9;             % Hz
prm.SSBlockPattern = 'Case B';      % Case A/B/C/D/E
prm.SSBTransmitted = [ones(1,8) zeros(1,0)];   % 4/8 or 64 in lengthprm.TxArraySize = [8 8];            % Transmit array size, [rows cols]
prm.TxAZlim = [-60 60];             % Transmit azimuthal sweep limits
prm.TxELlim = [-90 0];              % Transmit elevation sweep limitsprm.RxArraySize = [2 2];            % Receive array size, [rows cols]
prm.RxAZlim = [-180 180];           % Receive azimuthal sweep limits
prm.RxELlim = [0 90];               % Receive elevation sweep limitsprm.ElevationSweep = false;         % Enable/disable elevation sweep
prm.SNRdB = 30;                     % SNR, dB
prm.RSRPMode = 'SSSwDMRS';          % {'SSSwDMRS', 'SSSonly'}prm = validateParams(prm);%% Synchronization Signal Burst Configuration
%
% Set up the synchronization signal burst parameters by using the specified
% system parameters. For initial access, set the SSB periodicity to 20 ms.txBurst.BlockPattern = prm.SSBlockPattern;
txBurst.SSBTransmitted = prm.SSBTransmitted;
txBurst.NCellID = prm.NCellID;
txBurst.SSBPeriodicity = 20;
txBurst.NFrame = 0;
txBurst.Windowing = 0;
txBurst.DisplayBurst = true;% Assume same subcarrier spacing for carrier as the burst
carrier = nrCarrierConfig('NCellID',prm.NCellID,'NFrame',txBurst.NFrame);
carrier.SubcarrierSpacing = prm.SCS;
carrierInfo = nrOFDMInfo(carrier);
txBurst.SampleRate = carrierInfo.SampleRate;c = physconst('LightSpeed');   % Propagation speed
lambda = c/prm.CenterFreq;     % Wavelengthprm.posTx = [0;0;0];           % Transmit array position, [x;y;z], meters
prm.posRx = [100;50;0];        % Receive array position, [x;y;z], meterstoRxRange = rangeangle(prm.posTx,prm.posRx);
spLoss = fspl(toRxRange,lambda);    % Free space path loss% Transmit array
if prm.IsTxURA% Uniform rectangular arrayarrayTx = phased.URA(prm.TxArraySize,0.5*lambda, ...'Element',phased.IsotropicAntennaElement('BackBaffled',true));
else% Uniform linear arrayarrayTx = phased.ULA(prm.NumTx, ...'ElementSpacing',0.5*lambda, ...'Element',phased.IsotropicAntennaElement('BackBaffled',true));
end% Receive array
if prm.IsRxURA% Uniform rectangular arrayarrayRx = phased.URA(prm.RxArraySize,0.5*lambda, ...'Element',phased.IsotropicAntennaElement);
else% Uniform linear arrayarrayRx = phased.ULA(prm.NumRx, ...'ElementSpacing',0.5*lambda, ...'Element',phased.IsotropicAntennaElement);
end% Scatterer locations
prm.FixedScatMode = true;
if prm.FixedScatMode% Fixed single scatterer locationprm.ScatPos = [50; 80; 0];
else% Generate scatterers at random positionsNscat = 10;        % Number of scatterers azRange = -180:180;elRange = -90:90;randAzOrder = randperm(length(azRange));randElOrder = randperm(length(elRange));azAngInSph = azRange(randAzOrder(1:Nscat));elAngInSph = elRange(randElOrder(1:Nscat));r = 20;            % radius[x,y,z] = sph2cart(deg2rad(azAngInSph),deg2rad(elAngInSph),r);prm.ScatPos = [x;y;z] + (prm.posTx + prm.posRx)/2;
end% Configure channel
channel = phased.ScatteringMIMOChannel;
channel.PropagationSpeed = c;
channel.CarrierFrequency = prm.CenterFreq;
channel.SampleRate = txBurst.SampleRate;
channel.SimulateDirectPath = false;
channel.ChannelResponseOutputPort = true;
channel.Polarization = 'None';
channel.TransmitArray = arrayTx;
channel.TransmitArrayPosition = prm.posTx;
channel.ReceiveArray = arrayRx;
channel.ReceiveArrayPosition = prm.posRx;
channel.ScattererSpecificationSource = 'Property';
channel.ScattererPosition = prm.ScatPos;
channel.ScattererCoefficient = ones(1,size(prm.ScatPos,2));% Get maximum channel delay
[~,~,tau] = channel(complex(randn(txBurst.SampleRate*1e-3,prm.NumTx), ...randn(txBurst.SampleRate*1e-3,prm.NumTx)));
maxChDelay = ceil(max(tau)*txBurst.SampleRate);%% Burst Generation
%
% Create the SS burst waveform [ <#14 3> ] by calling the |hSSBurst| helper
% function. The generated waveform is not yet beamformed.% Create and display burst information
txBurstInfo = hSSBurstInfo(txBurst);
disp(txBurstInfo);% Generate burst waveform and grid
[burstWaveform,txBurstGrid] = hSSBurst(txBurst);%% Transmit-End Beam Sweeping
%
% To achieve TRP beam sweeping, beamform each of the SS blocks in the
% generated burst using analog beamforming. Based on the number of SS
% blocks in the burst and the sweep ranges specified, determine both the
% azimuth and elevation directions for the different beams. Then beamform
% the individual blocks within the burst to each of these directions.% Number of beams at both transmit and receive ends
numBeams = sum(txBurst.SSBTransmitted);% Transmit beam angles in azimuth and elevation, equi-spaced
azBW = beamwidth(arrayTx,prm.CenterFreq,'Cut','Azimuth');
elBW = beamwidth(arrayTx,prm.CenterFreq,'Cut','Elevation');
txBeamAng = hGetBeamSweepAngles(numBeams,prm.TxAZlim,prm.TxELlim, ...azBW,elBW,prm.ElevationSweep);% For evaluating transmit-side steering weights
SteerVecTx = phased.SteeringVector('SensorArray',arrayTx, ...'PropagationSpeed',c);% Apply steering per OFDM symbol for each SSB
carrier.NSizeGrid = txBurstInfo.NRB;
ofdmInfo = nrOFDMInfo(carrier);
gridSymLengths = repmat(ofdmInfo.SymbolLengths,1, ...size(txBurstGrid,2)/length(ofdmInfo.SymbolLengths));
%   repeat burst over numTx to prepare for steering
strTxWaveform = repmat(burstWaveform,1,prm.NumTx)./sqrt(prm.NumTx);
for ssb = 1:length(txBurstInfo.SSBIndex)% Extract SSB waveform from burstblockSymbols = txBurstInfo.OccupiedSymbols(ssb,:);startSSBInd = sum(gridSymLengths(1:blockSymbols(1)-1))+1;endSSBInd = sum(gridSymLengths(1:blockSymbols(4)));ssbWaveform = strTxWaveform(startSSBInd:endSSBInd,1);% Generate weights for steered directionwT = SteerVecTx(prm.CenterFreq,txBeamAng(:,ssb));% Apply weights per transmit element to SSBstrTxWaveform(startSSBInd:endSSBInd,:) = ssbWaveform.*(wT');end% Receive beam angles in azimuth and elevation, equi-spaced
azBW = beamwidth(arrayRx,prm.CenterFreq,'Cut','Azimuth');
elBW = beamwidth(arrayRx,prm.CenterFreq,'Cut','Elevation');
rxBeamAng = hGetBeamSweepAngles(numBeams,prm.RxAZlim,prm.RxELlim, ...azBW,elBW,prm.ElevationSweep);% For evaluating receive-side steering weights
SteerVecRx = phased.SteeringVector('SensorArray',arrayRx, ...'PropagationSpeed',c);% AWGN level
SNR = 10^(prm.SNRdB/20);                        % Convert to linear gain
N0 = 1/(sqrt(2.0*prm.NumRx*double(ofdmInfo.Nfft))*SNR); % Noise Std. Dev.% Generate a reference grid for timing correction
%   assumes an SSB in first slot
pssRef = nrPSS(carrier.NCellID);
pssInd = nrPSSIndices;
pbchdmrsRef = nrPBCHDMRS(carrier.NCellID,txBurstInfo.ibar_SSB(1));
pbchDMRSInd = nrPBCHDMRSIndices(carrier.NCellID);
pssGrid = zeros([240 4]);
pssGrid(pssInd) = pssRef;
pssGrid(pbchDMRSInd) = pbchdmrsRef;
refGrid = zeros([12*carrier.NSizeGrid ofdmInfo.SymbolsPerSlot]);
refGrid(txBurstInfo.OccupiedSubcarriers, ...txBurstInfo.OccupiedSymbols(1,:)) = pssGrid;% Loop over all receive beams
rsrp = zeros(numBeams,numBeams);
for rIdx = 1:numBeams% Fading channeltxWave = [strTxWaveform; zeros(maxChDelay,size(strTxWaveform,2))];fadWave = channel(txWave);% AWGN, after accounting for path lossnoise = N0*complex(randn(size(fadWave)),randn(size(fadWave)));rxWaveform = fadWave*(10^(spLoss/20)) + noise;% Generate weights for steered directionwR = SteerVecRx(prm.CenterFreq,rxBeamAng(:,rIdx));% Apply weights per receive elementif strcmp(prm.FreqRange, 'FR1')strRxWaveform = rxWaveform.*(wR');else  % for FR2, combine signal from antenna elementsstrRxWaveform = rxWaveform*conj(wR);end% Correct timingoffset = nrTimingEstimate(carrier, ...strRxWaveform(1:ofdmInfo.SampleRate*1e-3,:),refGrid*wR(1)');if offset > maxChDelayoffset = 0;endstrRxWaveformS = strRxWaveform(1+offset:end,:);% OFDM DemodulaterxGrid = nrOFDMDemodulate(carrier,strRxWaveformS);% Loop over all SSBs in rxGrid (transmit end)for tIdx = 1:numBeams% Get each SSB gridrxSSBGrid = rxGrid(txBurstInfo.OccupiedSubcarriers, ...txBurstInfo.OccupiedSymbols(tIdx,:),:);% Make measurements, store per receive, transmit beam        rsrp(rIdx,tIdx) = measureSSB(rxSSBGrid,prm.RSRPMode,txBurst.NCellID);end
end%% Beam Determination
%
% After the dual-end sweep and measurements are complete, determine the
% best beam-pair link based on the RSRP measurement.[m,i] = max(rsrp,[],'all','linear');    % First occurence is output
% i is column-down first (for receive), then across columns (for transmit)
[rxBeamID,txBeamID] = ind2sub([numBeams numBeams],i(1));% Display the selected beam pair
disp(['Selected Beam pair with RSRP: ' num2str(10*log10(rsrp(rxBeamID, ...txBeamID))+30) ' dBm', 13 '  Transmit #' num2str(txBeamID) ...' (Azimuth: ' num2str(txBeamAng(1,txBeamID)) ', Elevation: ' ...num2str(txBeamAng(2,txBeamID)) ')' 13 '  Receive #' num2str(rxBeamID) ...' (Azimuth: ' num2str(rxBeamAng(1,rxBeamID)) ', Elevation: ' ...num2str(rxBeamAng(2,rxBeamID)) ')' ]);% Display final beam pair patterns
h = figure('Position',figposition([32 55 32 40]),'MenuBar','none');
h.Name = 'Selected Transmit Array Response Pattern';
wT = SteerVecTx(prm.CenterFreq,txBeamAng(:,txBeamID));
pattern(arrayTx,prm.CenterFreq,'PropagationSpeed',c,'Weights',wT);h = figure('Position',figposition([32 55 32 40]),'MenuBar','none');
h.Name = 'Selected Receive Array Response Pattern';
wR = SteerVecRx(prm.CenterFreq,rxBeamAng(:,rxBeamID));
pattern(arrayRx,prm.CenterFreq,'PropagationSpeed',c,'Weights',wR);% Plot MIMO scenario with tx, rx, scatterers, and determined beams
prmScene = struct();
prmScene.txArraySize = prm.TxArraySize;
prmScene.rxArraySize = prm.RxArraySize;
prmScene.txElemPos = getElementPosition(arrayTx); % meters
prmScene.rxElemPos = getElementPosition(arrayRx); % meters
prmScene.txArrayPos = prm.posTx;
prmScene.rxArrayPos = prm.posRx;
prmScene.txAzAngles = -90:90;
prmScene.rxAzAngles = [90:180 -179:-90];
prmScene.scatPos = prm.ScatPos;
prmScene.lambda = lambda;
prmScene.arrayScaling = 1;
hPlotSpatialMIMOScene(prmScene,wT,wR);
if ~prm.ElevationSweepview(2);
endfunction prm = validateParams(prm)
% Validate user specified parameters and return updated parameters
%
% Only cross-dependent checks are made for parameter consistency.if strcmpi(prm.FreqRange,'FR1')if prm.CenterFreq > 7.125e9 || prm.CenterFreq < 410e6error(['Specified center frequency is outside the FR1 ', ...'frequency range (410 MHz - 7.125 GHz).']);endif strcmpi(prm.SSBlockPattern,'Case D') ||  ...strcmpi(prm.SSBlockPattern,'Case E')error(['Invalid SSBlockPattern for selected FR1 frequency ' ...'range. SSBlockPattern must be one of ''Case A'' or ' ...'''Case B'' or ''Case C'' for FR1.']);endif ~((length(prm.SSBTransmitted)==4) || ...(length(prm.SSBTransmitted)==8))error(['SSBTransmitted must be a vector of length 4 or 8', ...'for FR1 frequency range.']);endif (prm.CenterFreq <= 3e9) && (length(prm.SSBTransmitted)~=4)error(['SSBTransmitted must be a vector of length 4 for ' ...'center frequency less than or equal to 3GHz.']);endif (prm.CenterFreq > 3e9) && (length(prm.SSBTransmitted)~=8)error(['SSBTransmitted must be a vector of length 8 for ', ...'center frequency greater than 3GHz and less than ', ...'or equal to 7.125GHz.']);endelse % 'FR2'if prm.CenterFreq > 52.6e9 || prm.CenterFreq < 24.25e9error(['Specified center frequency is outside the FR2 ', ...'frequency range (24.25 GHz - 52.6 GHz).']);endif ~(strcmpi(prm.SSBlockPattern,'Case D') || ...strcmpi(prm.SSBlockPattern,'Case E'))error(['Invalid SSBlockPattern for selected FR2 frequency ' ...'range. SSBlockPattern must be either ''Case D'' or ' ...'''Case E'' for FR2.']);endif length(prm.SSBTransmitted)~=64error(['SSBTransmitted must be a vector of length 64 for ', ...'FR2 frequency range.']);endendprm.NumTx = prod(prm.TxArraySize);prm.NumRx = prod(prm.RxArraySize);    if prm.NumTx==1 || prm.NumRx==1error(['Number of transmit or receive antenna elements must be', ... ' greater than 1.']);endprm.IsTxURA = (prm.TxArraySize(1)>1) && (prm.TxArraySize(2)>1);prm.IsRxURA = (prm.RxArraySize(1)>1) && (prm.RxArraySize(2)>1);if ~( strcmpi(prm.RSRPMode,'SSSonly') || ...strcmpi(prm.RSRPMode,'SSSwDMRS') )error(['Invalid RSRP measuring mode. Specify either ', ...'''SSSonly'' or ''SSSwDMRS'' as the mode.']);end% Select SCS based on SSBlockPatternswitch lower(prm.SSBlockPattern)case 'case a'scs = 15;case {'case b', 'case c'}scs = 30;case 'case d'scs = 120;case 'case e'scs = 240;endprm.SCS = scs;endfunction rsrp = measureSSB(rxSSBGrid,mode,NCellID)
% Compute the reference signal received power (RSRP) based on SSS, and if
% selected, also PBCH DM-RS.sssInd = nrSSSIndices;                       % SSS indicesnumRx = size(rxSSBGrid,3);rsrpSSS = zeros(numRx,1);for rxIdx = 1:numRx% Extract signals per rx elementrxSSBGridperRx = rxSSBGrid(:,:,rxIdx);rxSSS = rxSSBGridperRx(sssInd);% Average power contributions over all REs for RSrsrpSSS(rxIdx) = mean(rxSSS.*conj(rxSSS));endif strcmpi(mode,'SSSwDMRS')pbchDMRSInd = nrPBCHDMRSIndices(NCellID);    % PBCH DM-RS indicesrsrpDMRS = zeros(numRx,1);for rxIdx = 1:numRx% Extract signals per rx elementrxSSBGridperRx = rxSSBGrid(:,:,rxIdx);rxPBCHDMRS = rxSSBGridperRx(pbchDMRSInd);% Average power contributions over all REs for RSrsrpDMRS(rxIdx) = mean(rxPBCHDMRS.*conj(rxPBCHDMRS));end        endswitch lower(mode)case 'sssonly'  % Only SSSrsrp = max(rsrpSSS);     % max over receive elementscase 'ssswdmrs' % Both SSS and PBCH-DMRSrsrp = max(rsrpSSS+rsrpDMRS)/2; % max over receive elementsend
end

本文内容参考:MATLAB2020帮助文档。

位置如下图所示：

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