Foundation: the coverage–bandwidth trade-off
Two pieces of physics govern everything. First, free-space path loss grows with the square of frequency — double the frequency and, all else equal, you lose ~6 dB, so high bands cover less area. Second, the absolute bandwidth available tends to grow with frequency — there is simply more room up high — and data rate scales with bandwidth. You cannot have maximum coverage and maximum capacity from the same band; you choose where on the curve to sit.
This is the same physics that gave 5G its FR1 (sub-7 GHz: wide coverage, modest bandwidth) and FR2 (mmWave: huge bandwidth, short, fragile links). 6G inherits the trade-off unchanged — only the chosen operating points are new.
ericsson.com 2026-01 secondaryThe upper mid-band — 6G's centre of gravity
The upper mid-band, informally FR3 (≈7.125–24.25 GHz in 3GPP), and especially the cmWave range 7–15 GHz, is widely seen as the leading candidate for initial 6G deployments: enough new bandwidth for multi-gigabit capacity, without the severe propagation fragility of mmWave. It is the band most studies expect 6G to "live" in first.
nokia.com 2026-01 secondaryFollowing WRC-23 (Resolution 256), WRC-27 agenda item 1.2 studies new IMT bands including ranges around 4.4–4.8 GHz, 7.125–8.4 GHz and 14.8–15.35 GHz, with regional candidates such as 6.425–7.125 GHz and 10–10.5 GHz. These studies — not 3GPP — decide what spectrum is legally available; 6G band specs follow the WRC outcome.
ericsson.com 2026-01 secondarySub-THz bands offer enormous bandwidth — attractive for short-range, fixed, or sensing-heavy use — but propagation, hardware and power challenges put mass deployment well after 2030, often framed around 2035+. Treat sub-THz as a research/early-phase candidate, not part of first-wave 6G.
arxiv.org 2024-06 secondaryWhy not just use mmWave again?
5G already opened mmWave (FR2). 6G's interest in 7–15 GHz is a direct response to what operators learned: mmWave's bandwidth is real but its coverage economics are punishing — many small cells, line-of-sight sensitivity, indoor penetration problems. The upper mid-band keeps a large slice of the capacity while restoring enough range to reuse existing macro grids. It is, deliberately, a compromise band.
| Band tier | Range | Typical BW | Coverage | Propagation | 6G role | Status |
|---|---|---|---|---|---|---|
| Sub-6 GHz / FR1 | 0.6–7.125 GHz | up to ~100 MHz | km-scale | Good indoors, penetrates walls | Coverage layer (reused) | foundation |
| Upper mid-band / cmWave | 7–15 GHz (within FR3) | up to ~500 MHz | 100 m–1 km | Good outdoors, limited indoor | Primary 6G target | candidate |
| FR3 upper | 15–24.25 GHz | up to ~800 MHz | 100–500 m | LOS sensitive | Capacity extension | candidate |
| FR2 mmWave | 24.25–71 GHz | up to ~2 GHz | 10–200 m | LOS only, easily blocked | Hot-spot / fixed access | foundation |
| sub-THz | 100–300 GHz | several GHz | < 50 m | Very short range, rain/O₂ absorption | Later-phase / ultra-dense (~2035+) | candidate |
| Frequency range | Scope | Notes | Status |
|---|---|---|---|
| 4.4–4.8 GHz | Global candidate | Complements mid-band; adjacent to existing 5G n77/n79 | requirement |
| 6.425–7.125 GHz | Regional candidate | Lower part of FR3; bridges sub-6 GHz and upper mid-band | requirement |
| 7.125–8.4 GHz | Global candidate | Core cmWave range; primary 6G initial deployment target | requirement |
| 10–10.5 GHz | Regional candidate | Complements cmWave; subject to interference studies | requirement |
| 14.8–15.35 GHz | Global candidate | Upper mid-band extension; shares with fixed satellite service | requirement |
Where this connects
Spectrum and the physical layer are inseparable: wider bandwidth at higher frequency is exactly why 6G studies wider-bandwidth numerologies. The bands you pick also shape RIS (which helps where high-band links are blocked) and sensing (which loves the wide bandwidth up high).