In parallel to the preparations for Day1 V2X mass-deployment, the development of Day2 enabling technologies is gearing up. New specifications have been developed: next generation DSRC (IEEE802.11bd) and next generation C-V2X (NR-V2X Rel. 16). The new state-of-the-art specifications open new possibilities, to name a few:
- Higher bandwidth: Day2 messages transmit objects detected by all vehicle sensors, which by far extends the content of Day1 messages that just report the status of vehicle. The new specifications can support the significant increase in bandwidth by effectively enabling 20MHz in 802.11bd and 40MHz in NR-V2X. In addition, higher 256-QAM modulation is supported for 802.11bd and NR-V2X.
- Reliable operation: NR-V2X introduces groupcasts, for increased reliability using a new Physical Sidelink Feedback Channel (PSFCH). Groupcast is valuable for cooperative driving, where one vehicle should know that the messages were received by the other vehicle. 802.11bd introduces a blind retransmission, similar to a concept existing in LTE-V2X.
- Faster speed robustness: Both 802.11bd and NR-V2X are targeted to operate at 500km/h relative speed between two vehicles. They gain greater robustness at higher speeds by adding midamble in 802.11bd and DMRS in NR-V2X case.
- Longer communication range: Both 802.11bd and NR-V2X are using LDPC error correction scheme and OFDM modulation. In addition, 802.11bd adds extra-range mode using Dual-Carrier Modulation (DCM), similar to LTE-V2X high-range operation with narrow channels.
- Configuration flexibility: NR-V2X extends the number of possible configurations, and includes sub-carrier spacing, for supporting short slots.
- Unicast support: NR-V2X adds unicast support, already supported by802.11p . 802.11bd further extends the support by adding MIMO to double the speed between two vehicles.
Although 802.11bd can co-exist in the same channel with 802.11p, the applicability of 802.11bd in Day1 is doubtful since a single vehicle with 802.11p in proximity should downgrade 802.11bd operation to 802.11p mode. Therefore, 802.11bd is expected to reach the market only when Day2 services are introduced. NR-V2X design goal supports Day2 and Day3, without Day1, which would continue to be supported by LTE-V2X.
Similar to 802.11p and LTE-V2X surpassing all the requirements of Day1 use-cases, having higher communication range and link capacity, we expect 802.11bd and NR-V2X to exceed Day2 and Day3 use-case requirements.
Autotalks is developing both 802.11bd and NR-V2X. Autotalks is committed to being at the cutting-edge of V2X technology and supports all global specifications.