# A Tutorial on 5G NR V2X Communications ## Citation M. H. C. Garcia et al., "A Tutorial on 5G NR V2X Communications," in IEEE Communications Surveys & Tutorials, vol. 23, no. 3, pp. 1972-2026, third quarter 2021, doi: 10.1109/COMST.2021.3057017. ## Summary A guide to the NR V2X (3GPP rel 16) with clear outlines of the channel models used. Minimal discussion on hardware used to implement it but extensive overview of the different symbols, bandwidths and protocol schemes. ^summary ## Notes - IN 1999, the US Federal Communications Commission (FCC) allocated 75 MHz of spectrum in the 5.9 GHz band for Intelligent Transportation Services (ITS). - DSRC based on IEEE802.11p in 5.9GHz band. - 3GPP Rel. 16 was the first to include 5G NR V2X with sidelinks (i.e. V2V). - Rel. 16 complements LTE V2X SL (sidelink) comms -  -  - SL CSI-RS is supported for unicast only. Sidelink Channel state information reference signal (SL CSI-RS): used for measuring channel state information (CSI) at the receiver that is then fed back to the transmitter. - The transmitter can adjust its transmission based on the fed back CSI. SL CSI-RS is sent within the PSSCH region of the slot. In NR V2X unicast[^21], link adaptation can be based on the feedback of a channel quality indicator (CQI) from an RX UE to the TX UE. To determine the CQI, an RX UE measures the sidelink channel from the TX UE using the SL CSI-RSs transmitted by the TX UE within the PSSCH region of the slot. The CQI is selected from a CQI table that is derived based on the configured MCS table for a PSSCH [46]. cross-RAT control allows for use of LTE-V2X Rel 16 introduced NLOSv where LOS path is blocked by another vehicle.   1. LOS: V2V link is in LOS state if the two vehicles are in the same street and the LOS path is not blocked by vehicles. 2. NLOS (LOS path blocked by buildings): V2V link is in NLOS state if the two vehicles are in different streets. 3. NLOSv (LOS path blocked by vehicles): V2V link is in NLOSv state if the two vehicles are in the same street and the LOS path is blocked by vehicles   Channel estimation: DMRS pattern #question what is this? sensor sharing needs high data rates (50-700 Mbps) for long distances (200 meters or beyond) [12] (see Table II) Beamforming allows for sensor sharing in the sidelink. 3GPP, "TR 22.186: Service requirements for enhanced V2X scenarios" (v16.2.0, Release 16),", 3GPP, Tech. Spec., Jun. 2019 ## References 1. [A Tutorial on 5G NR V2X Communications](../../Spaces/University/Thesis/literature%20review/secondary-search/a-tutorial-on-5g-nr-v2x-communications.pdf) 2. [DOI](https://doi.org/10.1109/COMST.2021.3057017) 3.  # Footnotes