DSRC and C-V2X — the comparison, and why the argument is over.
For roughly a decade this was the central fight in the industry. It is now substantially settled: every jurisdiction that has made a technology decision since 2018 has chosen C-V2X, and the United States has set a hard legal sunset for DSRC. The comparison still matters, because Europe's installed base is ITS-G5, because more than two million Volkswagens are driving around with it, and because the technical differences explain the outcome.
One is Wi-Fi, half-clocked. The other is the LTE uplink, repurposed.
DSRC / IEEE 802.11p / ITS-G5 is Wi-Fi, half-clocked. OFDM derived from 802.11a, 10 MHz channels rather than 20, 64-point FFT, 156.25 kHz subcarrier spacing, 8 µs symbols. Convolutional coding with Viterbi decoding. Data rates 3 to 27 Mbit/s, with 6 Mbit/s as the typical safety operating point. Channel access is CSMA/CA with EDCA — contention-based, no scheduler. It operates outside the context of a BSS: no association, no MAC-layer authentication. The North American stack is the IEEE 1609 WAVE family — 1609.2 for security, 1609.3 for networking and WSMP, 1609.4 for multi-channel operation. The European profile is ETSI ITS-G5 per EN 302 663, with GeoNetworking and BTP above it. Congestion is managed by Decentralized Congestion Control per ETSI TS 102 687.
C-V2X PC5 (LTE-V2X, Rel-14) is the LTE uplink, repurposed. SC-FDMA, 15 kHz subcarrier spacing, 1 ms subframes, 10 or 20 MHz channels, with minimum transmission bandwidth configurable down to 720 kHz. Turbo coding, which gives materially more coding gain in a fading channel than convolutional. Blind HARQ retransmission — one retransmission, soft-combined at the receiver — worth roughly 3 dB of additional link budget. Channel access is sensing-based semi-persistent scheduling, not contention. The C-V2X reference →
Three radios, one table.
| DSRC / ITS-G5 | LTE-V2X (Rel-14 PC5) | NR-V2X (Rel-16 PC5) | |
|---|---|---|---|
| PHY | OFDM, 802.11a-derived | SC-FDMA | CP-OFDM / DFT-s-OFDM |
| Subcarrier spacing | 156.25 kHz | 15 kHz | 15/30/60 kHz FR1; 60/120 kHz FR2 |
| Coding | Convolutional | Turbo | LDPC data, Polar control |
| Channel access | CSMA/CA, EDCA | Sensing + SPS, Mode 3/4 | Sensing + SPS, Mode 1/2 |
| GNSS synchronisation | Not required | Required | Required |
| HARQ | None | Blind retransmission, ~3 dB | Feedback-based via PSFCH |
| Cast types | Broadcast | Broadcast only | Unicast, groupcast, broadcast |
| Modulation ceiling | 64-QAM | 64-QAM | 256-QAM |
| Congestion metric | DCC | CBR/CR at 4 ms | CBR/CR at 1–2 ms |
| Link budget | Baseline | ~9 dB better | Better still |
| Behaviour under load | Contention collisions, growing latency tail | Graceful degradation | Graceful degradation, with pre-emption |
5GAA's field testing, submitted into the FCC record.
These are 5GAA figures, and 5GAA is the C-V2X industry alliance. They were submitted into a regulatory proceeding and were not successfully rebutted on the record, which is a reasonable standard — but they are attributed, not neutral.
| Metric | DSRC | C-V2X |
|---|---|---|
| Line-of-sight range | 625 m | 1,050 m (+68%) |
| Non-line-of-sight intersection, 90% reliability | 90–400 m | 600–800 m |
| Passing / overtake scenario | 240 m | 443 m |
| Range at 90% reliability under 80 MHz Wi-Fi interference | 550 m | 950 m (+73%) |
| Mean end-to-end latency, clean channel, 193-byte packet | 16–17 ms | 14–15 ms |
| 95th-percentile latency, same conditions | 18–20 ms | 22–23 ms |
Under adjacent-channel DSRC interference C-V2X showed a 2.9× range advantage; under U-NII-3 Wi-Fi interference, 1.7×. In a lab congestion test with 48 on-board units simulating dense highway traffic, packet error rate stayed below 10% with Channel Busy Ratio below 30%.
Two real advantages, and neither turned out to be decisive.
- No synchronisation dependency. 802.11p does not need GNSS time for the radio to function. C-V2X does. In deep tunnels, dense urban canyons and under jamming, that is a genuine architectural difference, mitigated but not eliminated by device-to-device synchronisation references.
- Maturity and installed base. Field-proven since roughly 2010, with a substantial deployed base of roadside units and, in Europe, more than two million Volkswagen vehicles. The OEM scoreboard →
A table of decisions.
| Jurisdiction | Decision | Date |
|---|---|---|
| China | LTE-V2X only, 5905–5925 MHz. No DSRC path. | October 2018 |
| United States | C-V2X only in the upper 30 MHz; DSRC phased out | Nov 2020 order, final rules Nov 2024, DSRC ceases 14 December 2026 |
| South Korea | C-V2X selected as the national C-ITS method; DSRC sunset June 2027 | December 2023 |
| Japan | 5.9 GHz assignment for V2X targeted for completion by FY2026 | MIC plan, Dec 2024 |
| India | C-V2X; DSRC explicitly rejected as not meaningfully deployed domestically | TRAI CP 08/2026, April 2026 |
| European Union | Technology neutral. The 2019 C-ITS Delegated Regulation was blocked by the Council on technology-neutrality grounds and never entered into force. Both remain permitted; the installed base is ITS-G5. | 2019 onward |
The recommendation, for anyone building today: C-V2X, and dual-mode only if the European ITS-G5 installed base is a market you must serve. Our own position is to specify NR-C-V2X for new infrastructure after a defined effective date, permit LTE-C-V2X for a transitional period, and require dual-mode LTE plus NR capability in roadside units deployed after that date.
Where this fits.
C-V2X
The winning radio, in the detail this comparison compresses.
Spectrum
The bands each decision above actually allocated.
US regulation
FCC 24-123, the transition timetable and the December 2026 sunset.
EU regulation
The delegated act that never was, and what filled the gap.
Chipsets and hardware
The dual-mode parts, for anyone who has to serve both markets.
Message sets
Why the same ETSI message rides either radio unchanged.
Questions this page answers.
Is DSRC dead?
Legally, in the United States, effectively yes: DSRC operations must cease by 14 December 2026, no new licences are being issued, and existing licences are renewable only up to that date. In South Korea, June 2027. In Europe it is very much alive, with a large installed base and full regulatory permission.
Which is better, DSRC or C-V2X?
On measured range, link budget, interference robustness and behaviour under congestion, C-V2X. On synchronisation independence and deployment maturity, DSRC. The regulatory outcome has settled the practical question in most markets regardless of the technical merits.
Why did Europe not choose C-V2X?
Europe did not choose either. The Commission's 2019 C-ITS Delegated Regulation was widely read as favouring ITS-G5, and the Council of the European Union objected to it on technology-neutrality grounds in July 2019; it never entered into force and no replacement has been adopted. EU spectrum decisions since have been written technology-neutrally, acknowledging both ITS-G5 and LTE-V2X.
Can a vehicle support both?
Yes. Dual-mode chipsets exist — Autotalks CRATON2 supports concurrent 802.11p and C-V2X PC5 operation, and TEKTON3 supports DSRC, LTE-V2X and NR-V2X. The cost is a second radio chain and a second antenna path.