FCC Part 15 Subpart E - UNII Rules - 47 CFR §15.407 | Updated 2021 6 GHz Report & Order (FCC 20-51)9 rows#
| UNII Band | Freq Range (MHz) | Max Conducted Power (dBm) | Max EIRP (dBm) | Max PSD (dBm/MHz) | DFS Required | TPC Required | Indoor Only | Notes / Key KDB |
|---|---|---|---|---|---|---|---|---|
| UNII-1 | 5150-5250 | 30 dBm (AP, 1 W); 24 dBm (client) | 30 dBm | 17 dBm/MHz (AP) | No | No | No (since FCC 14-30, 2014) | §15.407(a)(1). Indoor-only rule lifted 2014 (FCC 14-30). Outdoor AP EIRP above 30° elevation ≤ 125 mW (21 dBm) to protect satellite feeder links. No DFS/TPC. |
| UNII-2A | 5250-5350 | 24 dBm (250 mW) | 30 dBm | 11 dBm/MHz | YES - mandatory | Yes (6 dB below max; waived if EIRP < 500 mW) | No (both) | §15.407(a)(2). DFS + TPC mandatory. Radar types: short pulse, long pulse, FM chirp, FMCW. CAC = 60s. NOP = 30 min. |
| UNII-2C | 5470-5725 | 24 dBm (250 mW) | 30 dBm | 11 dBm/MHz | YES - mandatory | Yes (6 dB below max; waived if EIRP < 500 mW) | No (both) | §15.407(a)(3). Weather radar (TDWR) in this band - stricter radar avoidance. Ch 120/124/128 near airports: devices must avoid these channels without TDWR-avoidance mechanism. |
| UNII-3 | 5725-5850 | 30 dBm | 36 dBm (PtMP); PtP up to 53 dBm (23 dBi antenna, no power reduction required) | 17 dBm/MHz | No | No | No (outdoor allowed) | §15.407(a)(4). Highest power. No DFS. Overlaps 5.8 GHz ISM (§15.247). Fixed PtP links exempt from antenna-gain power reduction - up to 53 dBm EIRP. |
| UNII-4 | 5850-5925 | Indoor low power (5850-5895) | Per 5.9 GHz order | - | No | No | Yes (unlicensed part) | FCC Nov 2020 order: lower 45 MHz (5850-5895, chs 169/173/177) opened for unlicensed indoor; upper 30 MHz (5895-5925) retained for C-V2X/ITS. 802.11bd operates in the ITS portion. |
| UNII-5 | 5925-6425 | PSD-governed (LPI); VLP ≤14 dBm EIRP | 30 dBm (LPI) 14 dBm (VLP) | 5 dBm/MHz (EIRP PSD) (LPI) -5 dBm/MHz (VLP) | No (no radar) | No | LPI: Yes VLP: No | §15.407(a)(5). 6 GHz first sub-band. LPI = Low Power Indoor (≤30 dBm EIRP). VLP = Very Low Power (≤21 dBm EIRP, mobile/portable, any location). 500 MHz available. |
| UNII-6 | 6425-6525 | 17 dBm (LPI) | 30 dBm (LPI) | 5 dBm/MHz (EIRP PSD) | No | No | LPI: Yes | §15.407(a)(6). 100 MHz. LPI only. FCC 20-51. |
| UNII-7 | 6525-6875 | 17 dBm (LPI) 30 dBm (SP+AFC) | 30 dBm (LPI) 36 dBm (SP) | 5 dBm/MHz (EIRP PSD) (LPI) 23 dBm/MHz (SP) | No | No | LPI: Yes SP: No | §15.407(a)(7). 350 MHz. Standard Power (SP) requires AFC. Outdoor large-area coverage use case. |
| UNII-8 | 6875-7125 | 17 dBm (LPI) 30 dBm (SP+AFC) | 30 dBm (LPI) 36 dBm (SP) | 5 dBm/MHz (EIRP PSD) (LPI) 23 dBm/MHz (SP) | No | No | LPI: Yes SP: No | §15.407(a)(8). 250 MHz. Total 6 GHz availability in US: 1200 MHz (UNII-5+6+7+8). Largest Wi-Fi spectrum allocation in history. |
DFS Radar Types & Detection Requirements - FCC KDB 905462 D04 + ETSI EN 301 893 §4.78 rows#
| Radar Type | Pulse Width (µs) | PRI / PRF | Min Pulses to Detect | Detection Bandwidth | FCC Applies | ETSI Applies | ETSI Type # | Notes |
|---|---|---|---|---|---|---|---|---|
| Short Pulse (generic) | 0.5-5 µs | 1000-2000 µs PRI | 5 pulses | Full channel BW | Yes | Yes | Type 1 | Most common radar waveform. Standard DFS test waveform. AP must detect and vacate within 260 ms (CCTT). |
| Long Pulse | 1-100 µs | 1000-5000 µs PRI | 10 pulses | Full BW | Yes | Yes | Type 2 | Longer pulses from military/weather radars. Harder to detect at high PW. |
| FM Chirp | 1-5 µs (swept) | 1000-2000 µs PRI | 15 pulses | Full BW | Yes | Yes | Type 3 | Frequency-swept pulse. Used in some military systems. Frequency variation within pulse. |
| Short Pulse (dense) | 0.1-1 µs | 333 µs PRI (staggered) | 5 pulses | Full BW | No | Yes | Type 4 | ETSI only. High-PRF military radar. Staggered PRI makes detection harder. |
| Short Pulse (staggered) | 0.1-2 µs | Staggered: 333/500/666 µs | 10 pulses | Full BW | No | Yes | Type 5 | ETSI only. 3-period PRI stagger. Requires pattern recognition in AP. |
| FMCW (Stepped) | Variable | 1000 µs PRI | 15 bursts | Full BW | No | Yes | Type 6 | ETSI only. Frequency-hopping continuous wave. Used in some navigation radars. |
| TDWR (Terminal Doppler Weather Radar) | 1-2 µs | 833 µs PRI (rotating) | 15 pulses | Full BW | YES - special rules | N/A | N/A | FCC-specific. Airport vicinity. Channels 120/124/128 (5600-5640 MHz). Additional 30 dBm EIRP limit near TDWR. KDB requires TDWR-specific avoidance. |
| PAR (Precision Approach Radar) | 1 µs | 1000 µs PRI | 5 pulses | Full BW | Yes | Yes | Type 1 variant | Airport PAR. Similar to Type 1 but at specific airfield channels. |
DFS Procedure Timing Requirements - IEEE 802.11h + FCC/ETSI6 rows#
| Procedure | Duration | FCC Requirement | ETSI Requirement | Description | - | - | - | - |
|---|---|---|---|---|---|---|---|---|
| CAC (Channel Availability Check) | 60 seconds | 60 s mandatory | 60 s mandatory | AP must passively listen for 60 s before using a DFS channel (ETSI: 10 MINUTES on weather-radar channels 5600-5650 MHz / chs 120-128). No frames may be transmitted during CAC. If radar detected → channel cannot be used. | - | - | - | - |
| CCTT (Channel Closing Transmission Time) | < 260 ms | < 260 ms | < 260 ms | After radar detection: total channel move time ≤ 10 s, within which aggregate transmissions ≤ 260 ms (enough to send CSA to clients). | - | - | - | - |
| NOP (Non-Occupancy Period) | 30 minutes | 30 min | 30 min | After radar detection, channel cannot be reused for 30 min. AP must switch to alternate channel. Timer per channel. | - | - | - | - |
| ISM (In-Service Monitoring) | Continuous | Continuous | Continuous | After CAC, AP must continuously monitor for radar while operating. Must check entire channel BW including adjacent channels if bonded. | - | - | - | - |
| CSA (Channel Switch Announcement) | ≥ 1 beacon before switch | ≥ 1 beacon | ≥ 1 beacon | Action frame or beacon IE notifying clients of imminent channel switch. Count field decrements each beacon. | - | - | - | - |
| Uniform Spreading | Random channel selection | Encouraged | Required (ETSI) | AP should spread across available DFS channels to distribute load. Must not always return to same 'favorite' channel. | - | - | - | - |