TRS — CSI-RS configured for tracking

5G Systems Notes · Concept map · TRS Route · Hierarchy · Index · All concepts · Hub

Reference signals

Where it sits

Sits atLevel 6 of the hierarchy · Reference signals · explained
Also writtentracking reference signal
Learn firstCSI-RS — 6 concepts in the full chain, see the paths
UnlocksNothing else depends on it directly.
Primary clauseTS 38.214 §5.1.6.1.1
Used inref-signals 5 · index 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. Not a separate signal but a CSI-RS resource set configured for tracking — 3GPP calls it CSI-RS for tracking, TS 38.214 clause 5.1.6.1.1, and the configuration is TRS-ResourceSet.

What it is for. Fine time and frequency tracking. A device's oscillator drifts and the channel's delay shifts; a TRS is transmitted often enough, and with enough spacing between its resources, for the device to keep its estimates current without needing a full CSI report each time.

Its fingerprint appears in the PDSCH note without explanation. PDSCH §6.5 quotes clause 7.3.1.5's list of what PDSCH must not collide with, and one entry carves out "non-zero-power CSI-RS … not configured by the TRS-ResourceSet IE". The exception exists because a TRS is dense and frequent, and treating it like an ordinary CSI-RS would punch too many holes in PDSCH.

Read on

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

Widget not found: sim_status

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

To understand TRS (level 6) you first need 6 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
4 Antenna port
5 CSI-RS
Immediately before TRS: CSI-RS.
Keep going — where this sits on the route
◀CRSstep 62 · level 6
Step 63 of 118level 6 · Reference signals
Zero-power CSI-RSstep 64 · level 6▶
Nothing depends on this one directly
It is a leaf of the graph — follow the route rather than the branch.
↳ all 13 concepts at level 7 · level 6 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 · TRS Top · Concept map · Hub