Band n258 (26 GHz)
Understanding Band n258
Band n258 was identified as the pioneer mmWave band for European 5G at the World Radiocommunication Conference 2019 (WRC-19). The 3.25 GHz allocation (24.25 to 27.5 GHz) provides sufficient spectrum for multiple operators to deploy 400 MHz channel bandwidth carriers, enabling the multi-gigabit data rates that define the 5G enhanced mobile broadband (eMBB) use case. The band is shared between mobile 5G and existing fixed satellite service (FSS) earth stations, requiring spectrum sharing or relocation of incumbent users.
The proximity of Band n258 to the 23.8 GHz water vapor absorption line creates a unique regulatory challenge. Meteorological satellites use passive radiometers at 23.8 GHz to measure atmospheric water vapor for weather prediction. Out-of-band emissions from 5G base stations operating at 24.25 GHz can interfere with these measurements. WRC-19 established strict emission limits (−42 dBW/200 MHz EIRP) that constrain base station antenna design: the antenna must have sufficient out-of-band rejection to meet this limit while operating at full power in-band.
Band n258 Specifications
Uplink: 24.25 – 27.5 GHz (TDD, shared with DL)
Downlink: 24.25 – 27.5 GHz (TDD, shared with UL)
Channel Bandwidths (3GPP Release 15+):
50, 100, 200, 400 MHz per component carrier
Subcarrier spacing: 120 kHz (standard) or 240 kHz
EESS Protection Limit:
−42 dBW/200 MHz EIRP (WRC-19 initial limit)
−38 dBW/200 MHz EIRP (transitional, some administrations)
Typical Base Station EIRP:
55 to 65 dBm (316 W to 3.16 kW) per beam with 256-element array
n258 vs. n257: Regional Band Allocation
| Parameter | Band n258 (Europe/Asia) | Band n257 (US/Japan/Korea) |
|---|---|---|
| Frequency | 24.25 – 27.5 GHz | 26.5 – 29.5 GHz |
| Total Bandwidth | 3.25 GHz | 3 GHz |
| EESS Concern | Critical (adjacent to 23.8 GHz) | Minimal (separated by 2.7 GHz) |
| Incumbent Users | FSS earth stations, EESS | LMDS, FSS |
| Overlap | 1 GHz shared (26.5-27.5 GHz) | 1 GHz shared (26.5-27.5 GHz) |
| Auction Status | Auctioned in IT, DE, FI; planned in FR, ES | Completed in US, JP, KR |
Frequently Asked Questions
How does Band n258 differ from Band n257?
n258 (24.25 to 27.5 GHz) sits lower in frequency than n257 (26.5 to 29.5 GHz) with 1 GHz of overlap. n258 is the European harmonized band; n257 is the US/Japan/Korea allocation. n258's proximity to the 23.8 GHz water vapor line requires strict emission limits (−42 dBW/200 MHz EIRP) for EESS protection, which constrains European base station design and deployment density.
What are the propagation characteristics at 26 GHz?
Free-space path loss is 21.7 dB higher than at 2 GHz. Rain attenuation reaches 5 dB/km in moderate rain and 15 dB/km in heavy rain. Foliage loss is 10 to 20 dB. Modern insulated glass attenuates by 25 to 40 dB. Practical outdoor cell radius is 100 to 300 meters with beamforming. Indoor coverage requires dedicated small cells or repeaters since outdoor signals cannot reliably penetrate modern building envelopes.
What spectrum policy challenges affect Band n258 deployment?
Primary challenges include EESS protection at 23.8 GHz (strict out-of-band emission limits), coordination with incumbent FSS earth stations (requiring relocation or sharing frameworks), and maximum EIRP restrictions near radio astronomy sites. Despite these, European operators including Deutsche Telekom, Orange, and Vodafone have launched initial n258 deployments in Germany, Italy, and Finland.