Matlab Generate 5g Waveform

Critical Rules

These parameter constraints cause the most errors. An unedited simplified-constructor config (nrDLCarrierConfig(fr, bw, scs) / nrULCarrierConfig(fr, bw, scs)) already satisfies them; check the ones that apply to anything you change, or to a no-argument (manual) build, before calling nrWaveformGenerator. Apply only the fixes your layout needs, and follow Set Only What the Task Requires in SKILL.md for everything else.

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). Trailing zeros are implied, so a short vector is enough. For narrow bandwidths:

SSB Carrier Must Be at Least 20 RBs (Except at 3 MHz)

The SCS carrier at the SSB numerology must have NSizeGrid >= 20, except at ChannelBandwidth = 3 (below). Otherwise generation errors ("SCS carrier associated with the SSB must be 20 resource blocks or wider").

3 MHz exception: the PBCH is punctured. At 3 MHz the 15 kHz carrier is only 15 RBs, yet the Case A SSB is accepted and generation succeeds silently: the 20-RB (240-subcarrier) SSB is cut to the carrier, so PSS and SSS stay intact but about half the PBCH REs (including PBCH DM-RS) are punctured. This is 3GPP-sanctioned (Rel-17 3 MHz channel), not a bug — keep the SSB; do not disable it or move it to a wider carrier (the puncture affects PBCH decoding margin and SSB power measurements). The same 15-RB carrier at any wider ChannelBandwidth errors.

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';

An 11-RB data carrier (5 MHz / 30 kHz, 10 MHz / 60 kHz) cannot host the SSB itself, but a separate 20-RB SSB carrier still fits the channel — that is what the simplified constructor builds (see narrow-band-manual-config.md). Disable SSBurst (cfg.SSBurst.Enable = false) only when the task wants a single-carrier layout or no SSB.

Point A Centering Constrains Multi-Carrier Layouts

When multiple SCS carriers coexist, Point A centers the highest-SCS carrier, so a lower-SCS carrier may need fewer RBs than the bandwidth-table maximum (e.g. at 40 MHz a full 106-RB 30 kHz carrier leaves room for 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 reserves CSI-RS REs automatically, so 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:

% Start from the constructor's CSI-RS: its SymbolLocations clears PDCCH
% (a new nrWavegenCSIRSConfig defaults to symbol 0, on the CORESET).
csirs1 = cfg.CSIRS{1};       % BWP 1 (BandwidthPartID default 1 — don't restate it)
csirs1.Enable = true;        % the constructor ships CSI-RS disabled
csirs1.NumRB = 106;          % confine to PDSCH1's region (RBOffset default 0 — don't restate it)

csirs2 = csirs1;
csirs2.BandwidthPartID = 2;  % set only where it differs from the default 1
csirs2.NumRB = 53;
csirs2.RBOffset = 53;        % non-default offset — genuinely needed to clear PDSCH1

cfg.CSIRS = {csirs1, csirs2};

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. Keep CSI-RS off the CORESET symbols (0–1 by default) so the same placement also clears PDCCH — no need to touch the unrequested PDCCH. A new nrWavegenCSIRSConfig defaults to SymbolLocations = 0, which lands on the CORESET and conflicts with PDCCH. The simplified constructor's (disabled) CSIRS{1} instead holds a layout-specific symbol (3, 4, or 6) that clears both PDCCH and SSBurst, so just enabling it generates cleanly. Resizing it (NumRB/RBOffset) can reopen the SSBurst clash, so re-run.

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.

Two Codewords Need 5–8 Layers and a Matching DM-RS

A PDSCH or PUSCH carries 2 codewords only when NumLayers is 5–8 (TS 38.211 Table 7.3.1.3-1; 8-layer PUSCH is Rel-18 UL MIMO). The default DM-RS (type 1, single-symbol) supports only 4 ports, so NumLayers > 4 errors unless the DM-RS is also changed:

cfg.PDSCH{1}.NumLayers = 8;          % 2 codewords need 5–8 layers
cfg.PDSCH{1}.DMRS.DMRSLength = 2;    % default DM-RS caps at 4 ports

The same two lines apply to cfg.PUSCH{1} in an nrULCarrierConfig. A 2-codeword PUSCH also needs TransformPrecoding = false (the default); transform precoding supports only one codeword.

The DM-RS change is task-required, not over-config. nrWaveformGenerator sizes the antenna count to NumLayers automatically.

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.

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