PRS — Positioning reference signal

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Reference signals

Where it sits

Sits atLevel 4 of the hierarchy · Reference signals · explained
Learn firstOFDM symbol · Resource element — 4 concepts in the full chain, see the paths
UnlocksNothing else depends on it directly.
Primary clauseTS 38.211 §7.4.1.7, TS 38.214 §5.1.6.5
Used inref-signals 6 · index 1 · nr-frame-structure 1
Scanned from the notes at page load and joined with terms.json; nothing on this card is typed by hand.

What it is

What it is. A signal designed to be timed, not decoded. TS 38.211 clause 7.4.1.7, reception in TS 38.214 clause 5.1.6.5, on antenna ports from 5000.

Why positioning needs its own signal. Position is computed from differences in arrival time between several cells. That requires hearing cells you are not connected to — which are, by definition, weak — and measuring their timing precisely.

So PRS is built for two properties no other signal needs at once: very wide bandwidth, because timing resolution is inversely proportional to bandwidth; and good hearability, achieved by muting patterns that stop the serving cell from drowning the neighbours.

Release 19 added carrier phase positioning (TS 38.214 clause 5.1.6.5.2) and bandwidth aggregation for positioning (clause 5.1.6.5.3) — both attacking the same limit, that accuracy is bounded by bandwidth.

Read on

This concept was first written up in ref-signals, which reads the whole group as one argument.

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

To understand PRS (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 Resource element
Immediately before PRS: Resource element, OFDM symbol.
Keep going — where this sits on the route
◀PRACHstep 34 · level 4
Step 35 of 118level 4 · Reference signals
Modulationstep 36 · level 4▶
Nothing depends on this one directly
It is a leaf of the graph — follow the route rather than the branch.
↳ 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.
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