What is Numerology?
In 5G NR, numerology refers to the set of OFDM waveform parameters — primarily subcarrier spacing (SCS) and cyclic prefix duration — that define the time-frequency structure of the radio frame. Unlike LTE which used a fixed 15 kHz subcarrier spacing, 5G NR supports flexible numerology with SCS values of 15, 30, 60, 120, and 240 kHz (each being 2ⁿ × 15 kHz). This flexibility allows the same NR framework to operate across a wide range of frequencies and use cases — from low-band macro coverage to mmWave ultra-high-capacity deployments.
How Does Numerology Work?
Each numerology (μ = 0, 1, 2, 3, 4 corresponding to SCS = 15, 30, 60, 120, 240 kHz) defines the slot structure: as SCS doubles, the slot duration halves and the number of slots per subframe doubles. A 15 kHz slot lasts 1 ms (same as LTE), a 30 kHz slot lasts 0.5 ms, 60 kHz → 0.25 ms, and 120 kHz → 0.125 ms. Wider SCS provides shorter symbols, which reduces latency and increases tolerance to Doppler spread and phase noise — essential at higher frequencies. However, wider SCS also means a shorter CP, requiring a shorter channel delay spread. In FR1, SCS of 15 and 30 kHz are typically used; in FR2, 60 and 120 kHz are standard. 240 kHz is used only for SSB in FR2.
Use Cases
FR1 deployments using 15/30 kHz SCS for macro coverage, FR2 mmWave deployments using 120 kHz SCS, uRLLC applications benefiting from short slot durations, V2X and high-mobility scenarios requiring Doppler-resistant numerology, and mixed-numerology BWP (Bandwidth Part) configurations.
3GPP / Standards Reference
3GPP TS 38.211 (NR physical channels and modulation — numerology definition), 3GPP TS 38.300 (NR overall description)
Related Terms
OFDM | CP-OFDM | FR1 | FR2 | Latency
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
