Generate 5G NR Waveforms

Generate standard-compliant 5G NR downlink and uplink waveforms for test and measurement, simulation, and verification using nrWaveformGenerator.

When to Use

• Generate a 5G, NR, or New Radio waveform
• Create DL waveforms with PDSCH, PDCCH, SSBurst, CSI-RS
• Create UL waveforms with PUSCH, PUCCH, SRS
• Generate NR test model (TM) or fixed reference channel (FRC) waveforms
• Configure waveform parameters: bandwidth, SCS, modulation, power levels
• Create multi-bandwidth-part waveforms

When Not to Use

• Channel modeling or propagation — use nrCDLChannel, nrTDLChannel
• Receiver processing or decoding — use nrPDSCHDecode, nrDLSCHDecoder
• Link-level simulation end-to-end

API Choice

Do not use primitive-level functions (nrCarrierConfig + nrPDSCH + nrOFDMModulate) for waveform generation. These are for individual channel signal processing, not waveform construction. nrWaveformGenerator handles channel multiplexing, power scaling, and OFDM modulation correctly.

Workflow

Custom DL or UL Waveform

1. Create carrier config using the simplified constructor (R2026a+):

cfg = nrDLCarrierConfig('FR1', 20, 30);  % DL: FR1, 20 MHz, 30 kHz SCS
cfg = nrULCarrierConfig('FR1', 20, 15);  % UL: FR1, 20 MHz, 15 kHz SCS

This auto-populates SCSCarriers, BandwidthParts, SSBurst/CORESET (DL only), and a default PDSCH or PUSCH with valid parameters sized to the bandwidth.

Requires R2026a or later. On earlier releases, use the manual approach shown in the Narrow Bandwidth DL pattern — create nrDLCarrierConfig with no arguments and set SCSCarriers, BandwidthParts, and channels explicitly.

Constructor side effect: For DL, the constructor adds a dedicated SCS carrier for SSBurst if the requested SCS doesn't match the default SSB numerology. For example, nrDLCarrierConfig('FR1', 5, 30) creates a hidden 15 kHz carrier (20 RBs) for SSBurst Case A. Use manual config instead when you need exact control over the number of SCS carriers.

2. Customize channels — set only the properties the task requires; never restate a default (NumSubframes = 10, Modulation = 'QPSK', Enable = true, RNTI = 1). Worse, never overwrite a constructor-placed value with a different one (e.g. forcing a BWP's NStartBWP to 0 when the constructor centered it at 1) — that breaks the validated layout. Exception: a value the user asked for — write it with a comment.

cfg.PDSCH{1}.Modulation = '64QAM';       % non-default (the default is QPSK)
cfg.NumSubframes = 20;                    % 20 subframes = 20 ms; the default is 10

Power and DMRSPower (dB) are optional. DMRSPower is DM-RS power relative to data REs; per TS 38.214 Table 4.1-1 it is boosted 0, 3, or 4.77 dB for 1, 2, or 3 CDM groups without data. On R2026b+, DMRSPower = [] applies this automatically.

3. Oversample (optional) — set sample rate before generation for DAC playback:

cfg.SampleRate = 245.76e6;  % Oversampled rate (default: minimum for the BW)

4. Validate — check the critical rules in the next section before generating.

5. Generate and verify — validateConfig checks structural rules but does not detect channel conflicts (e.g., overlapping PDSCH/CSI-RS, CSI-RS/SSBurst). Always call nrWaveformGenerator to catch these:

[waveform, info] = nrWaveformGenerator(cfg);

6. Visualize — open the config in the 5G Waveform Generator app:

openInGenerator(cfg);

7. Inspect output:

sr = info.ResourceGrids(1).Info.SampleRate;
grid = info.ResourceGrids(1).ResourceGridBWP;

Test Model or FRC

hNRReferenceWaveformGenerator is an example helper — set up a working directory with setupExample before use (no path modification needed):

[exDir, ~] = setupExample('5g/NRTestModelWaveformGenerationExample', fullfile(tempdir, 'tmfrc'));
workDir = fullfile(tempdir, 'myTMWaveform');
mkdir(workDir);
copyfile(fullfile(exDir, '*'), workDir);
cd(workDir);

Then generate. Pass only the arguments the task specifies — trailing arguments (duplex mode, cell identity) default to 'FDD' and 1; omit them unless the task requires a specific value:

% Model, bandwidth, and SCS only — duplex mode defaults to 'FDD', ncellid to 1
wavegen = hNRReferenceWaveformGenerator('NR-FR1-TM1.1', '10MHz', '15kHz');
[waveform, waveinfo] = generateWaveform(wavegen);
displayResourceGrid(wavegen);

See references/test-models-and-frc.md for all valid model names and options.

Key Functions

If you need to verify property names, check valid values for a config object, or look up parameters not covered in this skill, consult the online documentation links in references/documentation-links.md.

Do not mix API levels. These primitive objects are incompatible with nrWaveformGenerator:

Critical Rules

These parameter constraints cause the most errors. Check all of them before calling nrWaveformGenerator.

Set Only What the Task Requires

Configure the minimum set of properties. Do not restate a value the constructor or object already holds (RNTI = 1, NumLayers = 1, CyclicPrefix = 'normal', BlockPattern = 'Case A', a BandwidthPartID or RBOffset equal to its default, an NStartGrid/NStartBWP the constructor set). Do not set cosmetic or auto fields (Label, NCellID, WindowingPercent, an explicit SampleRate = []). Do not set Modulation, DM-RS, or NumLayers unless the prompt names them. Enabling a component the prompt asks for (CSIRS.Enable = true, SSBurst.Enable = true) is required — that is not over-config. A comment explaining a default is fine; assigning it is not.

NSizeGrid Must Match Channel Bandwidth

Look up NSizeGrid from the bandwidth tables. The simplified constructor (R2026a+) handles this automatically. To look up values programmatically:

nrDLCarrierConfig.FR1BandwidthTable
nrDLCarrierConfig.FR2BandwidthTable

BWP Must Fit Within SCS Carrier

NStartBWP >= NStartGrid
NStartBWP + NSizeBWP <= NStartGrid + NSizeGrid

The BWP SubcarrierSpacing must exactly match one SCS carrier's SubcarrierSpacing.

CORESET Must Fit Within BWP

Each bit set to 1 in FrequencyResources allocates 6 RBs. Total must not exceed NSizeBWP:

6 * sum(FrequencyResources) <= NSizeBWP

Max bits to set: floor(NSizeBWP / 6). For narrow bandwidths:

SSB Carrier Must Be at Least 20 RBs

The SCS carrier at the SSB numerology must have NSizeGrid >= 20.

When the user does not specify SSB parameters, choose a BlockPattern that matches the user's SCS carrier so no extra carrier is needed: 15 kHz → Case A, 30 kHz → Case B, 60 kHz → Case B (FR1; add a 30 kHz carrier if none exists), 120 kHz → Case D.

When the user explicitly requests SSB parameters that require a different SCS than the main carrier, add a dedicated SCS carrier for the SSB:

% Example: user wants Case A (15 kHz SSB) on a 30 kHz carrier
scsSSB = nrSCSCarrierConfig;
scsSSB.SubcarrierSpacing = 15;
scsSSB.NSizeGrid = 20;        % Minimum for SSB
cfg.SCSCarriers{end+1} = scsSSB;
cfg.SSBurst.BlockPattern = 'Case A';

Disable SSBurst (cfg.SSBurst.Enable = false) only when the carrier is too narrow to support any SSB (e.g., 5 MHz / 30 kHz → 11 RBs at 30 kHz, no room for a 20-RB carrier at any SSB numerology).

Point A Centering Constrains Multi-Carrier Layouts

When multiple SCS carriers coexist, Point A is positioned so the highest-SCS carrier is centered within the channel bandwidth, so the lower-SCS carrier may need fewer RBs than the bandwidth table maximum (e.g. 40 MHz with a full 30 kHz carrier of 106 RBs fits only 214 RBs at 15 kHz, not the table's 216). Call validateConfig(cfg) and reduce NSizeGrid if needed.

CSI-RS Must Not Conflict With Other Channels

Within the same BWP, nrWaveformGenerator automatically reserves REs for CSI-RS — conflicts only arise between DM-RS and CSI-RS. Across different BWPs that overlap in frequency, CSI-RS defaults span the full BWP and can collide with PDSCH, PDCCH, or SSBurst. Fix with NumRB and RBOffset:

csirs1 = nrWavegenCSIRSConfig;   % targets BWP 1 (BandwidthPartID default 1 — don't restate it)
csirs1.NumRB = 106;       % Match PDSCH1 frequency region
csirs1.RBOffset = 0;
csirs1.SymbolLocations = 6;  % Avoid PDCCH symbols 0-2

csirs2 = nrWavegenCSIRSConfig;
csirs2.BandwidthPartID = 2;  % Set BandwidthPartID only where it differs from the default 1

The CSI-RS/SSBurst clash is wider than it looks: across different SCS (SSBurst Case A 15 kHz vs CSI-RS on a 30 kHz BWP) one SSB symbol maps to several on the CSI-RS grid, so a small SSB footprint forbids a broad band and a mid-slot guess (e.g. 8) lands inside it. Check every CSI-RS on any BWP; resolve in order, then re-run nrWaveformGenerator to confirm clean: (1) CSIRSPeriod (most robust) — steer CSI-RS to a slot the SSBurst skips (CSIRSPeriod = [10 1]), any numerology; (2) NumRB/RBOffset — a region clear of the SSBurst carrier; (3) SymbolLocations (last resort) — place at the slot end (13/12), never mid-slot.

PDCCH Conflicts With PDSCH Across BWPs or RNTIs

Within the same BWP and RNTI, nrWaveformGenerator automatically reserves REs for PDCCH (via the CORESET region). PDCCH conflicts with PDSCH when:

• They are on different overlapping BWPs
• They have different RNTIs on the same BWP

To resolve, separate them in time (SymbolAllocation, SlotAllocation) or frequency (PRBSet).

PDSCH/PUSCH PRBSet Must Fit Within BWP

Every RB in PRBSet must lie inside the BWP:

max(PRBSet) < NSizeBWP

Always set PRBSet explicitly to fit the BWP — PRBSet = 0:NSizeBWP-1 for full-band. An over-range PRBSet is invalid, and the reaction is release-dependent (through R2026a it errors; R2026b silently clips), so rely on neither. The default 0:51 overflows any BWP under 52 RBs (e.g. an 11-RB 5 MHz / 30 kHz carrier). PRBSet sets frequency allocation only — waveform length is fixed by bandwidth, SCS, and NumSubframes.

PDCCH Links Through SearchSpace to CORESET

PDCCH.SearchSpaceID must reference a valid SearchSpace, which must reference a valid CORESET via CORESETID. All IDs must exist.

Patterns

Basic DL Waveform

% 20 MHz, 30 kHz SCS downlink waveform with 64QAM PDSCH
cfg = nrDLCarrierConfig('FR1', 20, 30);
cfg.PDSCH{1}.Modulation = '64QAM';       % non-default (the default is QPSK)

[waveform, info] = nrWaveformGenerator(cfg);

% Plot resource grid. SSBurst (enabled by default) lives in a SEPARATE
% grid, so plot both the BWP data grid and the SS burst.
figure; tiledlayout(1,2);
nexttile; imagesc(abs(info.ResourceGrids(1).ResourceGridBWP(:,:,1)));
axis xy; xlabel('OFDM Symbols'); ylabel('Subcarriers'); title('DL Resource Grid (BWP)'); colorbar;
nexttile; imagesc(abs(info.ResourceGridSSBurst.ResourceGrid(:,:,1)));
axis xy; xlabel('OFDM Symbols'); ylabel('Subcarriers'); title('SS Burst Grid'); colorbar;

Basic UL Waveform

% 20 MHz, 15 kHz SCS uplink waveform with QPSK PUSCH
cfg = nrULCarrierConfig('FR1', 20, 15);
cfg.PUSCH{1}.Modulation = 'QPSK';         % explicit per request (also the default)

[waveform, info] = nrWaveformGenerator(cfg);

Plot the Power Spectrum

For the power spectrum (rather than the resource grid), pass the waveform and its sample rate to pspectrum — sr puts the frequency axis in real Hz:

sr = info.ResourceGrids(1).Info.SampleRate;
figure;
pspectrum(waveform(:,1), sr);   % first antenna; sr -> Hz frequency axis
title('5G NR Waveform Power Spectrum');

spectrumAnalyzer and pwelch also work; all need the sample rate.

Narrow Bandwidth DL (11-RB carriers: 5 MHz/30 kHz, 10 MHz/60 kHz)

Common configs like 5 MHz/30 kHz and 10 MHz/60 kHz resolve to just 11 RBs (TS 38.104) — too narrow for the default CORESET and a >=20-RB SSB carrier, so the defaults fail on generation.

On R2026a+, prefer the simplified constructor — it right-sizes the SSB carrier, BlockPattern, and CORESET automatically:

cfg = nrDLCarrierConfig('FR1', 5, 30);    % R2026a+; auto-adds a 15 kHz SSB carrier
% cfg = nrDLCarrierConfig('FR1', 10, 60); % likewise: auto-adds a 30 kHz Case B SSB carrier
[waveform, info] = nrWaveformGenerator(cfg);

On the manual path, three defaults fail on an 11-RB carrier (all fixed below): SSBurst Case A/15 kHz needs a 15 kHz carrier (disable it, or add an SSB carrier + Case B at 60 kHz); CORESET FrequencyResources (~48 RB) overflows (shrink to 1); PDCCH AggregationLevel = 8 needs 8 CCEs, a 1-group CORESET gives 2 (use AL1/AL2).

Use the manual pattern below on pre-R2026a releases, or to keep a single-SCS-carrier layout (no auto-added SSB carrier):

cfg = nrDLCarrierConfig;
cfg.ChannelBandwidth = 5;

% 5 MHz at 30 kHz -> 11 RBs (TS 38.104 bandwidth table)
cfg.SCSCarriers{1}.SubcarrierSpacing = 30;
cfg.SCSCarriers{1}.NSizeGrid = 11;

% BWP matches the SCS carrier (link the values so they can't drift apart)
cfg.BandwidthParts{1}.SubcarrierSpacing = cfg.SCSCarriers{1}.SubcarrierSpacing;
cfg.BandwidthParts{1}.NSizeBWP = cfg.SCSCarriers{1}.NSizeGrid;

cfg.SSBurst.Enable = false;   % no 20-RB SSB carrier fits in 11 RBs

% CORESET: 6 RBs per set bit; 1 group (6 RBs) is the max that fits 11 RBs.
% Keep Duration at its default 2 — a 1-group CORESET fails at Duration 1.
cfg.CORESET{1}.FrequencyResources = 1;

% Keep a working PDCCH in the narrow band: AggregationLevel 1 (1 CCE) fits.
cfg.SearchSpaces{1}.NumCandidates = [8 0 0 0 0];   % candidates only at AL1
cfg.PDCCH{1}.AggregationLevel = 1;                 % or cfg.PDCCH{1}.Enable = false

% PDSCH: fill the BWP. Required — the default 0:51 is invalid for 11 RBs
% (errors through R2026a, silently clips in R2026b), so set it by hand.
cfg.PDSCH{1}.PRBSet = 0:cfg.BandwidthParts{1}.NSizeBWP-1;

[waveform, info] = nrWaveformGenerator(cfg);

Test Model Waveform

% NR-FR1-TM1.1 at 10 MHz, 15 kHz SCS
% Only the requested arguments; duplex mode defaults to 'FDD', ncellid to 1
wavegen = hNRReferenceWaveformGenerator('NR-FR1-TM1.1', '10MHz', '15kHz');
[waveform, waveinfo] = generateWaveform(wavegen);
displayResourceGrid(wavegen);

To modify test model parameters (e.g., enable transport coding):

wavegen = makeConfigWritable(wavegen);
pdschArray = [wavegen.Config.PDSCH{:}];
[pdschArray.Coding] = deal(true);
wavegen.Config.PDSCH = num2cell(pdschArray);
[waveform, waveinfo] = generateWaveform(wavegen);

Multi-BWP Waveform

For waveforms with multiple bandwidth parts and numerologies, see references/multi-bwp-guidance.md.

Output Structure

[waveform, info] = nrWaveformGenerator(cfg) returns:

There is no field called ResourceGrid in info.ResourceGrids. Use ResourceGridBWP or ResourceGridInCarrier.

[waveform, waveinfo] = generateWaveform(wavegen) for hNRReferenceWaveformGenerator returns:

Conventions

• After generating a waveform, unless the user asks for something specific:
  1. Tell the user the waveform variable name and that it is in the workspace
  2. Plot the resource grid from info.ResourceGrids(k).ResourceGridBWP (BWP-sized, one per BWP); use ResourceGridInCarrier only for a full-carrier view. The SS burst is a separate grid — when SSBurst.Enable is true and the SS burst is asked for, also plot info.ResourceGridSSBurst.ResourceGrid (it is not part of ResourceGridBWP)
  3. Save the generation code as a .m script and open it in the MATLAB editor with edit('scriptName.m')
• Use nrWaveformGenerator, not primitive functions (nrPDSCH + nrOFDMModulate)
• Start with the simplified constructor nrDLCarrierConfig('FR1', bw, scs) when possible
• Use nrWavegenPDSCHConfig (not nrPDSCHConfig) with nrWaveformGenerator
• Correct property names: DMRSPower (not PowerDMRS), PTRSPower (not PowerPTRS), NSizeGrid (not NRB), ChannelBandwidth (not Bandwidth)
• SCSCarriers, BandwidthParts, CORESET, PDSCH, PUSCH are cell arrays — use {}
• SSBurst is a direct object — use . not {}
• Use tiledlayout/nexttile for multi-panel figures
• Always label axes with units and include figure titles
• Comment non-obvious, interdependent choices (why a given NSizeGrid, why SSBurst is disabled, why a specific AggregationLevel) so the code explains itself

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