The two frequency ranges
Frequency Range 2 (FR2): 24250 MHz – 52600 MHz (FR2-1), 52600 MHz – 71000 MHz (FR2-2).
FR1 bands — the coverage workhorse
FR1 covers the traditional cellular bands (700 MHz, 800 MHz, 1.8 GHz, 2.1 GHz) plus the new "C-band" (3.3–4.2 GHz) that is the primary 5G NR deployment band worldwide. Sub-6 GHz signals diffract around buildings and penetrate walls — giving usable coverage across large areas.
| Band | Uplink (MHz) | Downlink (MHz) | Duplex | Max BW | Notes |
|---|---|---|---|---|---|
| n1 | 1920–1980 | 2110–2170 | FDD | 20 MHz | LTE re-farm |
| n28 | 703–748 | 758–803 | FDD | 30 MHz | Rural coverage |
| n41 | 2496–2690 | 2496–2690 | TDD | 100 MHz | Sprint/T-Mobile US |
| n78 | 3300–3800 | 3300–3800 | TDD | 100 MHz | Primary global 5G ← our band |
| n79 | 4400–5000 | 4400–5000 | TDD | 100 MHz | Japan, China |
| n77 | 3300–4200 | 3300–4200 | TDD | 100 MHz | Superset of n78 |
FR2 — mmWave
Above 24 GHz, signals do not penetrate walls or diffract around obstacles. A person walking between the UE and the gNB can cause a 20 dB drop in signal. This makes FR2 unsuitable for wide-area coverage but ideal for high-capacity indoor venues (stadiums, airports, shopping centres) where the UE has line of sight.
The compensation for high path loss is extreme beamforming — FR2 devices use antenna arrays with 8–256 elements to focus signal energy. The beamforming and SSB beam sweep pages cover this in detail.
TDD vs FDD
Duplex mode determines how uplink and downlink are separated. Both can carry the same data — the difference is resource allocation:
FDD (Frequency Division Duplex): UL and DL use different frequency bands simultaneously. Simple, predictable latency, but requires paired spectrum — each operator needs two bands. Common at lower frequencies (700 MHz, 1800 MHz, 2100 MHz).
TDD (Time Division Duplex): UL and DL share the same frequency band but in different time slots. The ratio is configurable — operators can allocate more slots to DL for video streaming, or more to UL for video upload. Band n78 is TDD. Slot formats (the DL/UL/Flexible pattern per slot) are signalled by DCI 2_0 with SFI-RNTI.
Band n78 — our example cell
Band n78 (3300–3800 MHz) is the primary 5G band deployed globally — Finland, Germany, UK, Japan, South Korea, and dozens of other countries all use n78 for their main 5G rollout. Our example cell at 3498.24 MHz sits in the middle of n78.
// Band n78 basics: Frequency range = 3300–3800 MHz Duplex mode = TDD (same band UL and DL) Max channel BW = 100 MHz Supported SCS = 15, 30, 60 kHz Our SCS = 30 kHz (μ=1) // Our cell at GSCN 7845: f_SSB_center = 3498.24 MHz Channel center ≈ 3498.24 MHz Channel edges = 3448.24–3548.24 MHz (100 MHz) // Active RBs at 30 kHz SCS, 100 MHz BW (Table 5.3.2-1): N_RB = 273 RBs Active BW = 273 × 12 × 30 kHz = 98.28 MHz Guard bands = 0.86 MHz each side // GSCN formula for n78 (TS 38.104 §5.4.3.1): f = 3000 MHz + N × 1.44 MHz, N = 1...500 GSCN 7845: f = 3000 + 7845 × ... wait — see // Correct formula: f_SSB = 3000 + GSCN_offset × step // GSCN 7845 → 3498.24 MHz (derived in the GSCN section)