FR1 and FR2 — The two frequency ranges, and why they behave differently
RF and system
This page is the explanation. FR1 and FR2, live is the working
half — both pickers, all 78 operating bands and both channels drawn to scale, computed by
5G Simulation/ while the page loads, so they cannot drift from what is written here.
Where it sits
What it is
What they are. The two bands of spectrum NR is defined for, and they are definitions, not descriptions. TS 38.101-1 Table 5.1-1:
| Range | Frequencies | Numerologies used | What follows from the physics |
|---|---|---|---|
| FR1 | 410 MHz – 7 125 MHz | $\mu$ = 0, 1, 2 (15/30/60 kHz) | Propagates well, diffracts around obstacles. Bandwidth is scarce — 100 MHz is a large channel. This is where coverage comes from. |
| FR2-1 | 24 250 – 52 600 MHz | $\mu$ = 2, 3 (60/120 kHz) | Bandwidth is plentiful — 400 MHz channels. Blocked by walls, hands and rain; needs beamforming to close the link at all. |
| FR2-2 | 52 600 – 71 000 MHz | $\mu$ = 5, 6 (480/960 kHz) | Release 17. Phase noise dominates, which is why the numerologies jump — see frame structure §3.1. |
The ranges explain most of the differences elsewhere in these notes. FR2's larger flat overhead in the peak-rate formula (0.18 against FR1's 0.14, PDSCH §11.1) is the extra cost of beam management. Its need for PT-RS is phase noise. Its reliance on QCL type D is the narrow receive beam. One choice of band, and the rest follows.
Read on
This concept was first written up in ref-system, which reads the whole group as one argument.
Before this concept, the hierarchy says to learn the following — the full chain, in order:
FR1 and FR2 needs nothing first — it is one of the places to start reading.