What Is 5G? The System Behind the Label
Strip away the marketing and 5G is two specified systems — NR and the 5G Core — built by 3GPP against ITU-R's IMT-2020 requirements. What those requirements were, what shipped, and where the releases stand.
"5G" labels a handset icon, a spectrum auction and a vendor's product line. For an engineer it means something narrower: the system 3GPP specified from Release 15 onward to meet ITU-R's IMT-2020 requirements.
Two new systems, not one
NR is the radio: OFDM with a scalable numerology, operating in FR1 (410 MHz to 7.125 GHz) and FR2 (24.25 GHz upward, extended to 71 GHz in Release 17). What NR changed from LTE is covered separately.
5GC is the core: service-based, with control and user planes separated. How it is built is its own article.
They are independent enough to deploy apart, and most operators did exactly that. Non-standalone runs NR on the LTE core — NR throughput without 5G Core features.
The three usage scenarios
ITU-R M.2083 framed IMT-2020 around three scenarios, and M.2410 attached numbers:
| Scenario | What it wants | Headline requirement |
|---|---|---|
| eMBB | Throughput per unit spectrum | 20 Gbit/s downlink peak, 10 Gbit/s uplink |
| URLLC | Bounded latency and residual error | 1 ms user-plane latency; 1−10⁻⁵ for a 32-byte packet within 1 ms |
| mMTC | Device count and battery life | 10⁶ devices per km² |
The requirements conflict. eMBB wants large transport blocks and aggressive MCS; URLLC wants conservative MCS and no queueing; mMTC wants devices that are cheap and mostly asleep. 5G is not a system that does all three at once — it is one system that can be configured for any of them.
What actually shipped
eMBB came first and dominates. Release 15's non-standalone specification was completed early, in December 2017, specifically so commercial NR could launch on existing LTE cores. Commercial launches followed in 2019.
URLLC is specified and niche. Mini-slots, configured grants, pre-emption and PDCP duplication are all in Releases 15 and 16. Deployments are concentrated in private and industrial networks, where the operator controls the radio environment end to end.
mMTC was mostly met by LTE. 3GPP's IMT-2020 submission included LTE-M and NB-IoT for the massive scenario, and they remain the workhorses. NR RedCap, from Release 17, fills the mid-tier between them and full NR.
The capabilities people associate with 5G mostly need standalone. Slicing, QoS flows, VoNR and edge UPF placement are 5G Core features; an NSA network has none of them.
Where the releases stand
Releases 15 to 17 are the 5G phase. From Release 18 the name changes to 5G-Advanced — same radio, same core, further features. The first normative 6G specifications are expected in Release 21, against a new set of IMT-2030 capabilities.
The mental model
5G = NR + 5GC, specified by 3GPP against IMT-2020. Either half can be deployed without the other.
eMBB, URLLC, mMTC — three scenarios with conflicting targets, served by one configurable system.
eMBB shipped at scale; URLLC is niche; mMTC runs largely on LTE-M and NB-IoT.
Most "5G features" are 5G Core features, so NSA does not have them.
Further reading
- ITU-R M.2083 — IMT-2020 framework and usage scenarios
- ITU-R M.2410 — minimum technical performance requirements for IMT-2020
- 3GPP TS 38.300 — NR and NG-RAN overall description
- 3GPP TS 23.501 — 5G system architecture
Practise this on 5G6GTech
Our companion site turns these topics into flashcards and quizzes.
- Drill 5G concepts with the flashcard deck (opens on 5G6GTech in a new tab)
700 standards-aligned 5G concepts on a spaced-repetition schedule, covering RAN, the core and service-based architecture, the physical layer and 5G-Advanced.
- Test yourself in the 5G practice quiz (opens on 5G6GTech in a new tab)
Timed multiple-choice questions across the same 5G domains, with explanations for each answer.
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