URLLC and eMBB — The service classes, as configurations

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RF and system

Where it sits

Sits atLevel 12 of the hierarchy · RF and system · explained
The 3 of them
eMBB — enhanced mobile broadband — the throughput case
URLLC — ultra-reliable low-latency — 1−10⁻⁵ at 0.5 ms
mMTC — massive machine-type communication — the device-density case
Learn firstNumerology · HARQ · CQI — 22 concepts in the full chain, see the paths
UnlocksNothing else depends on it directly.
Primary clauseTR 38.913 §7.5, §7.9
Used innr-pdsch 7 · ref-session 6 · ref-system 5 · index 4
Scanned from the notes at page load and joined with terms.json; nothing on this card is typed by hand.

What it is

What they are. The three service classes 5G was designed around. They are not modes — the physical layer has no switch labelled URLLC. They are configurations, and every knob has already appeared in these notes.

ClassTargetClauseHow the physical layer delivers it
eMBB
enhanced mobile broadband		20 Gbit/s peak DL; 4 ms user-plane latencyTR 38.913 §7.1, §7.5Wide bandwidth, carrier aggregation, many layers, high MCS. The default assumption of every other note here.
URLLC
ultra-reliable low latency		1 − 10−5 for 32 bytes within 1 ms; 0.5 ms user-plane latencyTR 38.913 §7.9, §7.5High numerology, mapping type B (PDSCH §8.2), CQI table 3 aimed at 10−5 (§10.2), short allocations, PDCP duplication.
mMTC
massive machine-type		Connection density; 10 years battery; coverage at 164 dB MaxCLTR 38.913 §7.6, §7.11, §7.10Narrow bandwidth, aggressive DRX, repetition, and the reduced-capability device profiles.
Table 1: The three service classes, their targets from TR 38.913 clause 7, and the physical-layer settings that deliver each. The right-hand column is the point: nothing here is a new mechanism. URLLC is the same PDSCH as eMBB with four constants changed, which is the sense in which the service classes are configurations rather than modes.

PDSCH §12.3 checks the URLLC row arithmetically — a 120 kHz round trip is 375 µs against a 0.5 ms budget, which is why the numerology has to be high.

Read on

This concept was first written up in ref-system, 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 URLLC and eMBB (level 12) you first need 22 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 Cyclic prefix · Resource element · Slot
4 Antenna port · Modulation · Numerology · Physical layer
5 CSI-RS · Layer · Transport block
6 CRC · Precoding
7 CSI · Code block
8 LDPC
9 Rate matching
10 HARQ · MCS
11 CQI
Immediately before URLLC and eMBB: HARQ, Numerology, CQI.
Keep going — where this sits on the route
◀Link adaptationstep 112 · level 12
Step 113 of 118level 12 · RF and system
Policy controlstep 114 · level 12▶
Nothing depends on this one directly
It is a leaf of the graph — follow the route rather than the branch.
↳ all 1 concept at level 13 · level 12 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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