--- name: matlab/matlab-generate-5g-waveform source: https://app.decimal.ai/s/matlab-matlab-generate-5g-waveform@1/SKILL.md source_sha256: 6bc73296333e --- # 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 | Need | API | Notes | |------|-----|-------| | Standard test model (TM) | `hNRReferenceWaveformGenerator` | Predefined 3GPP configs. See [test-models-and-frc.md](references/test-models-and-frc.md) | | Fixed reference channel (FRC) | `hNRReferenceWaveformGenerator` | DL and UL FRCs | | Custom DL waveform | `nrDLCarrierConfig` + `nrWaveformGenerator` | Full control over all DL channels | | Custom UL waveform | `nrULCarrierConfig` + `nrWaveformGenerator` | Full control over all UL channels | **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+): ```matlab 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** — modify defaults or add channels: ```matlab cfg.PDSCH{1}.Modulation = '64QAM'; cfg.PDSCH{1}.Power = -3; cfg.PDSCH{1}.DMRSPower = -6; cfg.NumSubframes = 10; ``` 3. **Oversample (optional)** — set sample rate before generation for DAC playback: ```matlab 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: ```matlab [waveform, info] = nrWaveformGenerator(cfg); ``` 6. **Visualize** — open the config in the 5G Waveform Generator app: ```matlab openInGenerator(cfg); ``` 7. **Inspect output**: ```matlab 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): ```matlab [exDir, ~] = setupExample('5g/NRTestModelWaveformGenerationExample', fullfile(tempdir, 'tmfrc')); workDir = fullfile(tempdir, 'myTMWaveform'); mkdir(workDir); copyfile(fullfile(exDir, '*'), workDir); cd(workDir); ``` Then generate: ```matlab wavegen = hNRReferenceWaveformGenerator('NR-FR1-TM1.1', '10MHz', '15kHz', 'FDD'); [waveform, waveinfo] = generateWaveform(wavegen); displayResourceGrid(wavegen); ``` See [references/test-models-and-frc.md](references/test-models-and-frc.md) for all valid model names and options. ## Key Functions | Function / Class | Purpose | |-----------------|---------| | `nrWaveformGenerator` | Generate time-domain waveform from carrier config | | `nrDLCarrierConfig` | DL carrier config (wraps all DL channels) | | `nrULCarrierConfig` | UL carrier config (wraps all UL channels) | | `nrSCSCarrierConfig` | SCS carrier: `SubcarrierSpacing`, `NSizeGrid`, `NStartGrid` | | `nrWavegenBWPConfig` | BWP: `SubcarrierSpacing`, `NSizeBWP`, `NStartBWP` | | `nrWavegenPDSCHConfig` | PDSCH: `Modulation`, `Power`, `DMRSPower`, `PRBSet` | | `nrWavegenPUSCHConfig` | PUSCH: `Modulation`, `Power`, `DMRSPower` | | `nrWavegenPUCCH0Config` .. `nrWavegenPUCCH4Config` | PUCCH formats 0–4 | | `nrWavegenSRSConfig` | SRS config | | `nrWavegenPDCCHConfig` | PDCCH config (links via `SearchSpaceID`) | | `nrCORESETConfig` | CORESET: `FrequencyResources`, `Duration` | | `nrSearchSpaceConfig` | Links PDCCH to CORESET via IDs | | `nrWavegenSSBurstConfig` | SS burst: `BlockPattern`, `TransmittedBlocks` | | `nrWavegenCSIRSConfig` | CSI-RS config | | `hNRReferenceWaveformGenerator` | Standard TMs and FRCs (example helper) | | `validateConfig` | Check structural rules (method on carrier config) | | `openInGenerator` | Open config in 5G Waveform Generator app | 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](references/documentation-links.md). **Do not mix API levels.** These primitive objects are incompatible with `nrWaveformGenerator`: | Use with `nrWaveformGenerator` | Do NOT use with `nrWaveformGenerator` | |-------------------------------|--------------------------------------| | `nrDLCarrierConfig` / `nrULCarrierConfig` | `nrCarrierConfig` | | `nrWavegenPDSCHConfig` | `nrPDSCHConfig` | | `nrWavegenPUSCHConfig` | `nrPUSCHConfig` | ## Critical Rules These parameter constraints cause the most errors. Check all of them before calling `nrWaveformGenerator`. ### NSizeGrid Must Match Channel Bandwidth Look up `NSizeGrid` from the bandwidth tables. The simplified constructor (R2026a+) handles this automatically. To look up values programmatically: ```matlab 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: | NSizeBWP | Max bits | Example FrequencyResources | |----------|----------|---------------------------| | 11 | 1 | `[1 zeros(1,44)]` | | 24 | 4 | `[1 1 1 1 zeros(1,41)]` | | 51 | 8 | `[ones(1,8) zeros(1,37)]` | ### SSB Carrier Must Be at Least 20 RBs The SCS carrier at the SSB numerology must have `NSizeGrid >= 20`. | BlockPattern | SSB SCS | |-------------|---------| | Case A | 15 kHz | | Case B | 30 kHz | | Case C | 30 kHz | | Case D | 120 kHz | | Case E | 240 kHz | **When the user does not specify SSB parameters**, choose a BlockPattern that matches the user's SCS carrier so no extra carrier is needed: | User's SCS | Use BlockPattern | SSB SCS | |------------|-----------------|---------| | 15 kHz | Case A | 15 kHz | | 30 kHz | Case B | 30 kHz | | 60 kHz | Case B (FR1) | 30 kHz — add a 30 kHz carrier if none exists | | 120 kHz | Case D | 120 kHz | **When the user explicitly requests SSB parameters** that require a different SCS than the main carrier, add a dedicated SCS carrier for the SSB: ```matlab % Example: user wants Case A (15 kHz SSB) on a 30 kHz carrier scsSSB = nrSCSCarrierConfig; scsSSB.SubcarrierSpacing = 15; scsSSB.NSizeGrid = 20; % Minimum for SSB scsSSB.NStartGrid = 0; cfg.SCSCarriers{end+1} = scsSSB; cfg.SSBurst.BlockPattern = 'Case A'; ``` **Disable SSBurst only** when the carrier is too narrow to support any SSB (e.g., 5 MHz / 30 kHz → 11 RBs at 30 kHz, and no room for a 20-RB carrier at any SSB numerology): ```matlab cfg.SSBurst.Enable = false; ``` ### 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. This means the lower-SCS carrier may need fewer RBs than the bandwidth table maximum. For example, 40 MHz with a full 30 kHz carrier (106 RBs) only fits 214 RBs at 15 kHz, not the table value of 216. Always call `validateConfig(cfg)` to check, 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`: ```matlab csirs1 = nrWavegenCSIRSConfig; csirs1.BandwidthPartID = 1; csirs1.NumRB = 106; % Match PDSCH1 frequency region csirs1.RBOffset = 0; csirs1.SymbolLocations = 6; % Avoid PDCCH symbols 0-2 ``` CSI-RS can also conflict with SSBurst when their frequency regions overlap. This applies to any CSI-RS on any BWP — check each one. To resolve, try these approaches in order: 1. **`NumRB`/`RBOffset`** — narrow the CSI-RS to a frequency region that does not overlap the SSBurst carrier (works when SSBurst does not span the full bandwidth) 2. **`SymbolLocations`** — move CSI-RS to symbols not used by SSBurst 3. **`CSIRSPeriod`** — adjust periodicity and slot offset so CSI-RS avoids slots containing SSBurst The right fix depends on the overall parameter set. Always call `nrWaveformGenerator` to verify no conflicts remain. ### 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 ``` max(PRBSet) < NSizeBWP ``` For full-band allocation: `PRBSet = 0:NSizeBWP-1`. ### 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 ```matlab % 20 MHz, 30 kHz SCS downlink waveform with 64QAM PDSCH cfg = nrDLCarrierConfig('FR1', 20, 30); cfg.PDSCH{1}.Modulation = '64QAM'; cfg.NumSubframes = 10; [waveform, info] = nrWaveformGenerator(cfg); % Plot resource grid figure; imagesc(abs(info.ResourceGrids(1).ResourceGridBWP(:,:,1))); axis xy; xlabel('OFDM Symbols'); ylabel('Subcarriers'); title('5G NR DL Resource Grid'); colorbar; ``` ### Basic UL Waveform ```matlab % 20 MHz, 15 kHz SCS uplink waveform with QPSK PUSCH cfg = nrULCarrierConfig('FR1', 20, 15); cfg.PUSCH{1}.Modulation = 'QPSK'; cfg.NumSubframes = 10; [waveform, info] = nrWaveformGenerator(cfg); ``` ### Narrow Bandwidth DL (5 MHz, 30 kHz SCS) Narrow bandwidths need manual config because CORESET defaults are too wide. SSBurst must be disabled here because there is no SCS carrier at the SSB numerology. (The simplified constructor avoids this by adding one automatically.) ```matlab cfg = nrDLCarrierConfig; cfg.ChannelBandwidth = 5; cfg.SCSCarriers = {nrSCSCarrierConfig}; cfg.SCSCarriers{1}.SubcarrierSpacing = 30; cfg.SCSCarriers{1}.NSizeGrid = 11; % 5 MHz at 30 kHz cfg.BandwidthParts = {nrWavegenBWPConfig}; cfg.BandwidthParts{1}.SubcarrierSpacing = 30; cfg.BandwidthParts{1}.NSizeBWP = 11; % SSB needs 20 RBs — disable for 11-RB carrier cfg.SSBurst.Enable = false; % CORESET: max 1 group (6 RBs) for 11-RB BWP cfg.CORESET{1}.FrequencyResources = [1 zeros(1,44)]; cfg.CORESET{1}.Duration = 2; % Must be 2 for interleaved mapping with 1 group cfg.PDCCH{1}.Enable = false; % Only 2 CCEs — too few for default AggregationLevel % PDSCH: fit within BWP cfg.PDSCH{1}.PRBSet = 0:10; cfg.PDSCH{1}.Power = -3; cfg.PDSCH{1}.DMRSPower = -6; [waveform, info] = nrWaveformGenerator(cfg); ``` ### Test Model Waveform ```matlab % NR-FR1-TM1.1 at 10 MHz, 15 kHz SCS wavegen = hNRReferenceWaveformGenerator('NR-FR1-TM1.1', '10MHz', '15kHz', 'FDD'); [waveform, waveinfo] = generateWaveform(wavegen); displayResourceGrid(wavegen); ``` To modify test model parameters (e.g., enable transport coding): ```matlab 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](references/multi-bwp-guidance.md). ## Output Structure `[waveform, info] = nrWaveformGenerator(cfg)` returns: | Field | Contents | |-------|----------| | `waveform` | Complex time-domain samples (N x P, P = antennas) | | `info.ResourceGrids(k).ResourceGridBWP` | Grid sized to BWP (NSizeBWP*12 subcarriers) | | `info.ResourceGrids(k).ResourceGridInCarrier` | Grid sized to full carrier | | `info.ResourceGrids(k).Info.SampleRate` | Waveform sample rate | | `info.ResourceGridSSBurst.ResourceGrid` | SSB grid (DL only) | | `info.WaveformResources.PDSCH` | Per-slot PDSCH resources (indices, symbols) | **There is no field called `ResourceGrid` in `info.ResourceGrids`.** Use `ResourceGridBWP` or `ResourceGridInCarrier`. `[waveform, waveinfo] = generateWaveform(wavegen)` for `hNRReferenceWaveformGenerator` returns: | Field | Contents | |-------|----------| | `waveinfo.ResourceGridBWP` | Resource grid | | `waveinfo.Info.SampleRate` | Sample rate | ## 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 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 Copyright 2026 The MathWorks, Inc.