SSB Beam Planner
Plan a 5G NR SSB burst set. Pick a frequency range and SSB subcarrier spacing and the tool derives the burst-set case (A–E), Lmax candidate count, and the exact OFDM-symbol positions inside the 5 ms half-frame per 3GPP TS 38.213 §4.1.
FR1 uses 15/30 kHz. FR2 uses 120/240 kHz.
5 ms half-frame timeline (140 OFDM symbols at SSB SCS)
Each coloured block is a 4-symbol SSB candidate. Hover to highlight its row in the table below.
Candidate SSB start positions (8 beams)
| Beam # | First symbol (l) | Slot | Symbol in slot |
|---|---|---|---|
| #0 | 2 | 0 | 2 |
| #1 | 8 | 0 | 8 |
| #2 | 16 | 1 | 2 |
| #3 | 22 | 1 | 8 |
| #4 | 30 | 2 | 2 |
| #5 | 36 | 2 | 8 |
| #6 | 44 | 3 | 2 |
| #7 | 50 | 3 | 8 |
About SSB burst sets
A 5G NR Synchronization Signal Block (SSB) is 4 OFDM symbols wide (PSS, PBCH, SSS, PBCH) and occupies 240 subcarriers. The gNB transmits up to Lmax of these in a single burst set, each beamformed in a different direction. The UE performs beam-sweep reception during initial access and picks the strongest SSB index. TS 38.213 §4.1 defines five cases (A–E) for how those candidate SSBs are placed in the 5 ms half-frame.
Case A (15 kHz) and Case C (30 kHz) use the symbol set {2, 8} + 14n. Case B (30 kHz, multiplexed with LTE) uses {4, 8, 16, 20} + 28n. Case D (120 kHz) and Case E (240 kHz) are FR2-only and carry up to 64 candidate SSB indices for the much tighter pencil beams needed at mmWave.
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