U-NII Bands
U-NII (Unlicensed National Information Infrastructure) bands are regulatory sub-bands within the 5 GHz spectrum defined by the FCC for unlicensed wireless communication under 47 CFR §15.407. These bands are essential for Wi-Fi systems, particularly those operating under IEEE 802.11a/n/ac/ax Wi-Fi standards.
Scope and Band Structure
The 5 GHz spectrum is subdivided into U-NII bands, each with distinct regulatory constraints. This classification is important for Wi-Fi device certification and deployment.
| Band | Details |
|---|---|
| U-NII-1 |
Frequency Range: 5150–5250 MHz Typical Channels: 36, 40, 44, 48 Usage Notes: Indoor use only |
| U-NII-2A |
Frequency Range: 5250–5350 MHz Typical Channels: 52, 56, 60, 64 Usage Notes: DFS required, indoor use |
| U-NII-2C |
Frequency Range: 5470–5725 MHz Typical Channels: 100–144 Usage Notes: DFS required, indoor/outdoor permitted |
| U-NII-3 |
Frequency Range: 5725–5850 MHz Typical Channels: 149–165 Usage Notes: Outdoor use permitted, no DFS |
| U-NII-4 |
Frequency Range: 5850–5895 MHz Typical Channels: n/a Usage Notes: Indoor unlicensed operation permitted; adjacent ITS/C-V2X band begins at 5895 MHz |
| Band | Frequency Range (MHz) | Typical Channels | Usage Notes |
|---|---|---|---|
| U-NII-1 | 5150–5250 | 36, 40, 44, 48 | Indoor use only |
| U-NII-2A | 5250–5350 | 52, 56, 60, 64 | DFS required, indoor use |
| U-NII-2C | 5470–5725 | 100–144 | DFS required, indoor/outdoor permitted |
| U-NII-3 | 5725–5850 | 149–165 | Outdoor use permitted, no DFS |
| U-NII-4 | 5850–5895 | n/a | Indoor unlicensed operation permitted; adjacent ITS/C-V2X band begins at 5895 MHz |
Channel 144 was introduced later in the regulatory framework and may not be supported by older Wi-Fi devices.
Note on Extended 5 GHz Channels
In addition to the standardized U-NII bands, some frequency planning tools and vendor implementations display extended 5 GHz channels such as 169 (5845 MHz) and 173 (5865 MHz). These channels:
lie outside the standard U-NII channel plan defined for Wi-Fi operation under FCC §15.407
may appear in planning tools but are not part of the standard unlicensed Wi-Fi channel allocations
are not approved for general Wi-Fi operation
While adjacent to U-NII-4 in frequency, these extended channels are governed by separate regulatory provisions and must not be confused with unlicensed Wi-Fi channels operating under FCC Part 15 Subpart E.
Regulatory Use and Constraints
DFS (Dynamic Frequency Selection) is mandatory in U-NII-2A and U-NII-2C to protect weather radar and military radar systems.
Transmit power and antenna gain limits vary by band and device class (e.g., low-power indoor, standard power).
Devices must comply with FCC §15.407 requirements, including:
Automatic channel selection
DFS behavior (where applicable)
Band-specific power and usage restrictions
Indoor/outdoor use restrictions must be enforced through device design, including firmware configuration and hardware limitations.
International Variations
Many other regions follow similar sub-band structures but may differ in:
Channel numbering and availability
DFS enforcement requirements
Transmit power limits and operational constraints
Examples include regulatory frameworks such as:
Devices must therefore be regionally configured to comply with local regulatory requirements.
6 GHz U-NII Expansion
6 GHz Band Structure
The 6 GHz spectrum used for unlicensed Wi-Fi operation is subdivided into four regulatory bands.
| Band | Details |
|---|---|
| U-NII-5 |
Frequency Range: 5925–6425 MHz Typical Use: Standard power with AFC, LPI, VLP |
| U-NII-6 |
Frequency Range: 6425–6525 MHz Typical Use: LPI, VLP |
| U-NII-7 |
Frequency Range: 6525–6875 MHz Typical Use: Standard power with AFC, LPI, VLP |
| U-NII-8 |
Frequency Range: 6875–7125 MHz Typical Use: LPI, VLP |
| Band | Frequency Range (MHz) | Typical Use |
|---|---|---|
| U-NII-5 | 5925–6425 | Standard power with AFC, LPI, VLP |
| U-NII-6 | 6425–6525 | LPI, VLP |
| U-NII-7 | 6525–6875 | Standard power with AFC, LPI, VLP |
| U-NII-8 | 6875–7125 | LPI, VLP |
Standard-power operation is limited to U-NII-5 and U-NII-7 and requires Automated Frequency Coordination (AFC) to protect incumbent licensed services.
Device Classes in the 6 GHz Band
Low-Power Indoor (LPI) devices are permitted across the full 6 GHz band and are restricted to indoor operation.
Very Low Power (VLP) operation was authorized for U-NII-5 and U-NII-7 in the FCC Second Report and Order (FCC 23-89, adopted November 2023) and later expanded to U-NII-6 and U-NII-8 in the Third Report and Order adopted in December 2024.
Standard-Power Access Points require Automated Frequency Coordination (AFC) to dynamically assign frequencies and power levels while protecting licensed incumbent services such as fixed microwave links.
Related Pages
Author: IBL-Editors Team
Technical Review: Daniel Lenhardt - CEO & Owner | IB-Lenhardt AG Give feedback on this article