LTE-V2X, NR-V2X and 5.9 GHz — what the C-V2X terms actually mean.
5.9 GHz says where a V2X radio transmits. LTE-V2X or NR-V2X says how. PC5 says the link is direct.
Those three get used interchangeably, which is why “C-V2X at 5.9 GHz” seems to contradict the existence of both an LTE and a 5G version. This page separates the terms, shows why 3GPP Band 47 and band n47 cover the same 5855–5925 MHz, and lists the questions that tell you what a piece of V2X hardware can actually do.
If C-V2X runs at 5.9 GHz, how can there be both LTE-V2X and 5G NR-V2X? The question is reasonable, and the confusion behind it goes away once three things that usually get said in one breath are pulled apart:
- Frequency says where the radio transmits. 5.9 GHz is a range of spectrum. It is not LTE and it is not 5G.
- Radio technology says how it transmits. LTE-V2X and NR-V2X are two generations of 3GPP radio that can both use the same spectrum around 5.9 GHz.
- V2X says what the link is for: vehicle-to-vehicle, vehicle-to-infrastructure, vehicle-to-pedestrian and vehicle-to-network communication.
Think of 5.9 GHz as a road. LTE-V2X is one kind of vehicle on it, NR-V2X is another, and the Wi-Fi-derived DSRC and ITS-G5 radios have used parts of the same 5.9 GHz ITS spectrum too. The frequency alone does not tell you which technology is in use.
Most of the confusion is a category error.
| Term | What kind of thing it is | The question it answers |
|---|---|---|
| 5.9 GHz | Radio spectrum, allocated by national regulators | Where? |
| C-V2X | The 3GPP family of Cellular Vehicle-to-Everything technologies | Which family? |
| LTE-V2X or NR-V2X | A radio access technology within that family | How? |
| PC5 or Uu | An interface: direct sidelink, or the cellular network | Direct or through a network? |
| Release 14, 15, 16… | A generation of the 3GPP specifications | Which version? |
| BSM, CAM, DENM, CPM, MAP, SPaT | Messages carried over the radio | What information? |
So “PC5” is not a frequency, “5.9 GHz” is not a technology, and “C-V2X” on its own does not say which radio generation is meant.
“Cellular” does not mean every message goes through a tower.
C-V2X has two paths. PC5 is the direct sidelink: car to car, car to roadside unit, roadside unit to car, with no base station in the middle. Uu is the ordinary cellular path: vehicle to base station to network and server.
That gives a more precise version of a common statement. C-V2X is not itself “the 5.9 GHz technology”. Direct C-V2X over PC5 is what is associated with the 5.9 GHz ITS spectrum; network-based V2X over Uu uses an operator's normal licensed bands. PC5 is still not a frequency: current 3GPP specifications also define NR V2X sidelink bands outside 5.9 GHz, such as n38 at 2570–2620 MHz. The 5.9 GHz ITS band is the case this page is about. PC5 and Uu side by side, with the full release history →
Band 47 and n47 cover the same 70 MHz. The radio changes, the spectrum does not.
| LTE-V2X | NR-V2X | |
|---|---|---|
| Also called | LTE C-V2X, LTE PC5, E-UTRA V2X, Rel-14/15 C-V2X | 5G NR-V2X, NR sidelink, NR PC5 |
| First specified | 3GPP Release 14 | 3GPP Release 16 |
| Study report | 3GPP TR 36.785 — V2V services based on LTE sidelink | 3GPP TR 38.885 — Study on NR Vehicle-to-Everything |
| 3GPP PC5 band at 5.9 GHz | Band 47, 5855–5925 MHz (3GPP TS 36.101) | Band n47, 5855–5925 MHz (3GPP TS 38.101-1) |
| Channel bandwidths | 10 or 20 MHz | 10, 20, 30 or 40 MHz |
| Cast types | Broadcast | Broadcast, groupcast and unicast |
| Retransmission | Blind, no receiver feedback | HARQ feedback for unicast and groupcast; none for broadcast |
Why one is 47 and the other n47. 3GPP numbers LTE (E-UTRA) bands plainly and prefixes NR bands with “n”. In this case the two numbers mark two radio technologies on identical frequency limits, not two different frequency ranges. ETSI EN 303 798, the European LTE-V2X and NR-V2X access-layer specification for this band, references both: Band 47 for LTE-V2X and band n47 for NR-V2X.
Spectrum is still regulated nationally. 3GPP defines what a radio can do across 5855–5925 MHz. A national regulator decides which part of that range may actually be used, by which technology and under what conditions — 30 MHz in the United States, 20 MHz in China, and DSRC rather than C-V2X in Singapore. A product for several markets has to distinguish what the specification supports from what each regulator permits. Allocations, jurisdiction by jurisdiction →
Where the figures come from. Band 47 and its 10 and 20 MHz channel bandwidths: 3GPP TS 36.101, Tables 5.5G-1 and 5.6G.1-1. Band n47 and its 10, 20, 30 and 40 MHz channel bandwidths: 3GPP TS 38.101-1, Tables 5.2E.1-1 and 5.3E.1-1. The European mapping of both bands to 5855–5925 MHz: ETSI EN 303 798 V2.1.1, clause 4.2.
Same spectrum does not mean the same radio.
LTE-V2X and NR-V2X differ in the physical layer, the channel structure, resource allocation, the MAC procedures, sidelink control, modulation and coding, feedback and QoS handling. A modem or chipset has to implement the specific sidelink it claims. Three things follow for anyone selecting hardware:
- 5.9 GHz RF support is not C-V2X support. A front end that tunes to the band says nothing about the radio protocol behind it.
- LTE-V2X support is not NR-V2X support. NR-V2X is not a drop-in replacement for an LTE-V2X radio, even at the same frequency.
- A 5G modem is not an NR-V2X modem. A module can carry ordinary 5G connectivity through a mobile network and have no NR sidelink at all.
NR-V2X complements LTE-V2X; it does not retire it. 3GPP's Release 16 NR-V2X work states that NR-V2X is not intended to replace the services LTE-V2X offers, but to complement it for advanced V2X services — the ones that need unicast, groupcast and feedback, such as coordinated manoeuvres, platooning and sensor sharing.
One channel for both is not the normal deployment model. ETSI EN 303 798 notes that deploying LTE-V2X and NR-V2X in the same channel could be possible, but is not intended and is outside the scope of that specification. 3GPP has specified coexistence between the two sidelinks, including a Release 18 co-channel mechanism described in 3GPP TS 38.300, yet planning still starts from separate carriers — and from how much spectrum a jurisdiction has authorised. Coexistence and the NR-V2X detail →
The message is not the radio.
| Layer | Examples |
|---|---|
| Application | Collision warning, signal-phase advisory, hazard notification |
| Messages | BSM, CAM, DENM, CPM, MAP, SPaT |
| Networking and transport | IEEE 1609.3 WSMP, or ETSI GeoNetworking and BTP |
| Radio access | LTE-V2X PC5, or NR-V2X PC5 |
| Spectrum | The 5.9 GHz ITS band, as each regulator allocates it |
The layering is deliberate: the messages are meant to be independent of the radio that carries them. The message sets → · The ITS station architecture →
“5.9 GHz C-V2X” leaves out the part that matters.
A complete description names the spectrum, the radio generation, the interface and the release:
- 5.9 GHz LTE-V2X PC5, 3GPP Release 14 — the first-generation direct radio.
- 5.9 GHz NR-V2X PC5, 3GPP Release 16 or later — the 5G sidelink.
Those two lines do not contradict each other. When evaluating an on-board unit, roadside unit, module or development platform, ask the supplier four questions:
- Does it support LTE-V2X PC5?
- Does it support NR-V2X PC5?
- Which 3GPP releases does it implement?
- Which operating bands and regional configurations does it support?
The answers say far more about what the hardware can do than “supports 5.9 GHz C-V2X” ever will. What the current silicon supports →
Release 14 LTE-V2X over PC5, and nothing broader.
Described in the terms above, the direct radio on AmbiOBU and AmbiRSU is a 5.9 GHz LTE-V2X PC5 subsystem at 3GPP Release 14. Release 15 is not part of the baseline, and NR-V2X is not included.
Both platforms also carry a separate 4G LTE module for backhaul and telemetry, which is the third point of section 4 in practice: that module is an ordinary cellular connection and does not provide PC5. Above the radio, Ambimat is developing the higher-layer V2X messaging software; message security is still in development. The AmbiV2X Developer Stack →
Where this fits.
Questions this page answers.
Is C-V2X 4G or 5G?
Both, as generations of one family. LTE-V2X is based on LTE and was introduced in 3GPP Release 14. NR-V2X uses 5G New Radio and was introduced in Release 16. A device can support one without the other.
Does C-V2X always use 5.9 GHz?
No. Direct C-V2X over the PC5 sidelink is associated with the ITS spectrum around 5.9 GHz. C-V2X over the Uu network interface uses an operator's ordinary cellular bands.
Can LTE-V2X and NR-V2X both operate at 5.9 GHz?
Yes. 3GPP defines LTE-V2X Band 47 and NR-V2X band n47 over the same 5855–5925 MHz for PC5, but they are different radio interfaces. Running both in one channel is not the normal deployment model: ETSI EN 303 798 notes that it could be possible, but is not intended and is outside that specification's scope. What actually runs where depends on the channels each regulator authorises.
If a modem supports 5G, does it support NR-V2X?
Not necessarily. Ordinary 5G network connectivity and the NR-V2X PC5 sidelink are separate capabilities. The specification has to state NR-V2X or NR PC5 support explicitly.
Is PC5 the same as 5.9 GHz?
No. PC5 is the direct V2X sidelink interface between devices; 5.9 GHz is radio spectrum. PC5 describes how two devices talk, not the frequency they use, and 3GPP defines NR V2X sidelink bands outside 5.9 GHz too, such as n38.
Which C-V2X do AmbiOBU and AmbiRSU support?
5.9 GHz LTE-V2X PC5 at 3GPP Release 14. Release 15 is not part of the baseline and NR-V2X is not included. Their separate 4G LTE module is a cellular backhaul path and does not provide PC5. The AmbiV2X Developer Stack.
Last updated 2026-10-06 · Technical reference maintained by Ambimat Electronics, Ahmedabad, India. Corrections: v2x@ambimat.com