4G LTE vs 5G NR
5G NR is the new radio standardised in 3GPP Release 15 onward, and it normally pairs with a redesigned 5G Core (5GC). 4G is the LTE radio sitting on top of the Evolved Packet Core (EPC). So "4G vs 5G" is really two changes at once: a new air interface and a new core.
The headline gains are higher peak rates, lower air-interface latency, and far more spectrum to work with — including mmWave. But the deeper change is structural. LTE was built mainly for mobile broadband. 5G adds flexible numerology on the radio, a service-based 5GC that splits the old monolithic nodes into separate network functions, and network slicing so one physical network can carry isolated logical networks with different latency and throughput targets.
How much of that you actually see depends on the band, the bandwidth, and whether the operator runs 5G in standalone mode or bolted onto LTE.
| Aspect | 4G LTE | 5G NR |
|---|---|---|
| Radio access (downlink / uplink) | OFDMA down, SC-FDMA (DFT-s-OFDM) up — single-carrier uplink for a lower PAPR | CP-OFDM both directions; DFT-s-OFDM available on the uplink for coverage-limited UEs |
| Core network | EPC — point-to-point interfaces between dedicated nodes (MME, S/PGW, HSS, PCRF) | 5GC — service-based architecture (SBA): NFs expose HTTP/2 APIs over a common bus |
| Base station | eNB (E-UTRAN Node B) | gNB (NR Node B); ng-eNB serves LTE radio into the 5GC |
| Peak data rate (spec) | ~1 Gbps down with carrier aggregation (Cat 16+) | up to ~20 Gbps down / 10 Gbps up in IMT-2020 targets |
| Air-interface latency | ~10 ms round trip in practice; ~4 ms one-way user-plane target | as low as ~1 ms one-way user-plane with the right numerology and a URLLC config |
| Subcarrier spacing | Fixed 15 kHz | Flexible numerology: 15/30/60/120 kHz (µ = 0–3), chosen per band |
| Channel bandwidth | ≤ 20 MHz per carrier; wider only via carrier aggregation | ≤ 100 MHz per carrier in FR1 (sub-6), ≤ 400 MHz per carrier in FR2 (mmWave) |
| MIMO and beamforming | Up to 8 layers; FD-MIMO added later, mostly sub-6 GHz | Massive MIMO with many antenna elements; analogue/hybrid beamforming, essential at mmWave |
| Network slicing | Not in the standard (closest is dedicated APNs / DECOR) | Built in — S-NSSAI identifies a slice end to end across RAN and 5GC |
| Spectrum | Mostly sub-3 GHz licensed bands | Sub-6 GHz (FR1) plus mmWave 24–52 GHz (FR2) |
| Voice | VoLTE — voice as an IMS packet service over the LTE bearer | VoNR over 5G NR; many SA networks still fall back to VoLTE (EPS fallback) early on |
| Key NF / node mapping | MME (mobility + session signalling); S-GW + P-GW carry the user plane | MME splits into AMF (mobility) + SMF (session); the S/PGW user plane becomes the UPF |
Radio: what actually changed
Both LTE and NR are OFDM systems, so the jump is more about flexibility than a brand-new waveform. LTE locked everything to 15 kHz subcarrier spacing and a downlink-only OFDMA scheme, using SC-FDMA (DFT-s-OFDM) on the uplink to keep the peak-to-average power ratio down so phone power amplifiers stayed efficient.
NR keeps CP-OFDM in both directions but adds scalable numerology: the subcarrier spacing can be 15, 30, 60 or 120 kHz. Wider spacing means shorter symbols and shorter slots, which is how NR shortens the transmission time interval and chases low latency. It also lets one framework cover everything from a 700 MHz coverage layer to a 28 GHz mmWave carrier. DFT-s-OFDM is still available on the NR uplink for cell-edge users who need the PAPR benefit.
The other big lever is bandwidth and antennas: a single NR carrier can be 100 MHz in FR1 or 400 MHz in FR2, versus LTE's 20 MHz per carrier. Pair that with massive MIMO and beamforming and most of the real-world throughput gain comes from sheer spectrum and spatial multiplexing, not the waveform itself.
Core: EPC vs the service-based 5GC
The EPC is a set of dedicated boxes wired together with named interfaces — the MME handles mobility and session signalling, the S-GW and P-GW carry user traffic, and the HSS and PCRF sit alongside for subscriber data and policy.
The 5GC restructures this as a service-based architecture. Functions are decomposed and talk over HTTP/2 APIs on a shared bus instead of fixed point-to-point links, which makes it easier to scale, update, or relocate one function without touching the rest. The mapping is worth memorising:
- MME → AMF + SMF. Mobility/registration goes to the AMF; session management goes to the SMF.
- S-GW + P-GW user plane → UPF. The user plane is pulled out as its own function (CUPS), so it can sit close to the edge while control stays central.
- HSS → UDM/UDR, PCRF → PCF, with the NRF added for service discovery.
This split is what makes slicing and edge deployments practical, rather than the radio change alone.
Do they coexist? (NSA, DSS)
Early 5G almost always ran Non-Standalone (NSA): the phone anchors on an LTE eNB for control signalling and adds an NR carrier for extra data throughput. That arrangement is EN-DC (E-UTRA–NR Dual Connectivity), and it reuses the existing EPC, so an operator gets 5G data speeds without first deploying a 5GC. Standalone (SA) is the full picture — gNB plus 5GC — and it's required for slicing, VoNR and the lowest latency.
Spectrum sharing bridges the gap. DSS (Dynamic Spectrum Sharing) lets LTE and NR share the same band, with the scheduler splitting resources between the two on a subframe-by-subframe basis according to demand. It's how operators light up 5G on existing low bands for coverage before they have dedicated spectrum to clear — at some cost in efficiency from the shared overhead.
The bottom line
5G NR plus the 5GC is a genuine step up in capacity, latency and flexibility — flexible numerology, far more spectrum, massive MIMO, and a service-based core that finally makes slicing and edge user planes practical.
But the size of the gain is set by deployment, not the spec sheet. On a shared low band running DSS in NSA mode, the day-to-day experience is closer to good LTE than to the 20 Gbps headline. The big numbers need wide FR1 carriers or mmWave, a standalone 5GC, and decent backhaul.
Meanwhile LTE isn't going anywhere soon. It stays the coverage backbone under 5G, carries voice via VoLTE on most networks for years, and anchors NSA deployments. Treat 5G as the capacity and latency layer you add on top of LTE — not a like-for-like replacement that arrives overnight.
Frequently asked questions
- Is 5G just faster 4G?
- No. Higher speed is one part, but the bigger differences are flexible radio numerology, much wider channels (up to 100 MHz in FR1, 400 MHz in FR2), and a redesigned service-based core that supports network slicing and edge user planes. A lot of 5G capability — slicing, VoNR, sub-millisecond latency — comes from the 5GC and standalone mode, not from raw speed.
- What's the real latency difference?
- LTE air-interface round-trip latency lands around 10 ms in practice. 5G NR can reach about 1 ms one-way on the user plane with wide subcarrier spacing and a URLLC configuration. In a typical mobile-broadband deployment you usually see single-digit improvement rather than the theoretical floor, because end-to-end latency also depends on the core, backhaul and the server you are talking to.
- Can 4G and 5G share spectrum?
- Yes, with DSS (Dynamic Spectrum Sharing). The scheduler divides the same band between LTE and NR dynamically, per subframe, based on demand. It lets operators add 5G to existing low bands for coverage before clearing dedicated spectrum, at some efficiency cost from the shared overhead. NSA deployments also pair an LTE anchor with an NR carrier via EN-DC.
- Will 4G be switched off?
- Not for a long time. LTE remains the coverage backbone under 5G, anchors NSA, and carries voice as VoLTE on most networks until VoNR is widespread. Operators are gradually refarming 2G/3G spectrum to 4G and 5G first; a broad 4G shutdown is years out and will follow 5G standalone coverage being good enough to carry voice and IoT everywhere.
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