Zero-power CSI-RS — A declared hole — a signal that is not transmitted

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Reference signals

Where it sits

Sits atLevel 6 of the hierarchy · Reference signals · explained
Also writtenZP CSI-RS · zero-power
Learn firstCSI-RS — 6 concepts in the full chain, see the paths
UnlocksNothing else depends on it directly.
Primary clauseTS 38.211 §7.4.1.5, TS 38.214 §5.1.4
Used inref-signals 4 · index 1 · nr-pdsch 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 CSI-RS configuration whose resource elements are simply left empty. There is no signal at all; the configuration exists so PDSCH is mapped around those elements. PDSCH §7.2 lists it among the furniture.

Why declare a hole? Because the hole is for somebody else. A neighbouring cell — or another device in this cell — is transmitting a real CSI-RS in exactly those elements, and measuring it is only meaningful if this cell is quiet there.

This is interference coordination expressed as a resource-mapping rule. No message is exchanged, no protocol runs; one cell is simply configured to be silent where another is configured to be loud. It is the cheapest coordination mechanism in the standard, and it exists because the alternative — actually cancelling interference at the receiver — is far harder.

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 Zero-power CSI-RS (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 Zero-power CSI-RS: CSI-RS.
Keep going — where this sits on the route
◀TRSstep 63 · level 6
Step 64 of 118level 6 · Reference signals
CRCstep 65 · 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.
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