Beamforming — Aiming energy rather than spraying it

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

Space — layers, ports, reporting

Where it sits

Sits atLevel 7 of the hierarchy · Space — layers, ports, reporting · explained
Also writtenbeam
Learn firstPrecoding — 8 concepts in the full chain, see the paths
UnlocksNothing else depends on it directly.
Primary clauseTS 38.214 §5.1.6.1.2
Used inref-mimo 4 · nr-srs 4 · nr-pdsch 3 · 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. Adding signals from several elements so they arrive in phase at one place and out of phase elsewhere. SRS §1.1 lists it as the first thing CSI is for.

Analogue — one transmit chain, phase shifters in the RF path. Cheap, and the whole array points one way at a time. This is what makes FR2 practical and what makes beam sweeping necessary.

Digital — one transmit chain per element, beams formed in baseband. Any number of simultaneous beams, at the cost of a chain per element.

Hybrid — a few chains, each feeding a sub-array of phase shifters. What real base stations actually do.

Beam management is the procedure of keeping the pointer correct: sweep during the SSB burst (ref-signals §5), refine with CSI-RS, report with L1-RSRP (TS 38.214 clause 5.1.6.1.2), and track the choice through QCL type D. On the device side it is also an SRS usage value — beamManagement, the first row of the table in SRS §4.2.

Read on

This concept was first written up in ref-mimo, 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 Beamforming (level 7) you first need 8 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 · Modulation
5 Layer
6 Precoding
Immediately before Beamforming: Precoding.
Keep going — where this sits on the route
◀CSIstep 76 · level 7
Step 77 of 118level 7 · Space
RNTIstep 78 · level 7▶
Nothing depends on this one directly
It is a leaf of the graph — follow the route rather than the branch.
↳ all 8 concepts at level 8 · level 7 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 · Beamforming Top · Concept map · Hub