Frame and subframe — 10 ms and 1 ms — the only fixed durations in NR

5G Systems Notes · Concept map · Frame and subframe Route · Live ↗ · Hierarchy · Index · All concepts · Hub

The grid and its units

This page is the explanation. frame, live is the working half — the same quantities computed by 5G Simulation/ while the page loads, so they cannot drift from what is written here.

Where it sits

Sits atLevel 4 of the hierarchy · The grid and its units · explained
The 1 of them
subframe — the 1 ms tenth of a frame — the one unit that does not change with the numerology
Learn firstSlot — 4 concepts in the full chain, see the paths
UnlocksTDD and FDD
Primary clauseTS 38.211 §4.3.1
Used innr-frame-structure 38 · nr-pdsch 4 · ref-signals 1
Scanned from the notes at page load and joined with terms.json; nothing on this card is typed by hand.

What it is

A frame is 10 ms and a subframe is 1 ms. They are the only durations in NR that do not change with numerology, which makes them the anchor everything else is derived from.

A frame holds ten subframes; a subframe holds $2^{\mu}$ slots. So the count of slots per subframe is the numerology index, and checking that the symbols in a subframe add up to exactly one millisecond is the arithmetic that validates the whole time structure.

Read on

The full treatment is in nr-frame-structure — this page is the definition and the map reference; that note is where the subject is actually developed.

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Before this concept, the hierarchy says to learn the following — the full chain, in order:

To understand Frame and subframe (level 4) you first need 4 other concepts. Read them in this order — everything on one line can be read in any order, but no line before the one above it:
Level Learn these
0 Subcarrier
1 OFDM
2 OFDM symbol
3 Slot
Immediately before Frame and subframe: Slot.
Keep going — where this sits on the route
◀Numerologystep 30 · level 4
Step 31 of 118level 4 · The grid and its units
Resource blockstep 32 · level 4▶
Level 4 → 5 · this unlocks
TDD and FDD
↳ all 14 concepts at level 5 · level 4 in full · the whole route
The route is every concept in the folder ordered by level, so nothing here needs anything after it. Computed at page load from terms.json; the same numbering as the route page.
5G Systems Notes · Concept map · Frame and subframe Top · Concept map · Hub