# Evolution of V2X Communication and Integration of Blockchain for Security Enhancements
## 3 Evolution of V2X Technologies  
The state-of-the-art vehicular networking technology, such as IEEE 802.11p and C-V2X, cannot fulfill the demands for next-generation autonomous vehicles that require ultra-reliable communication for critical and safety applications. Thus, the next-generation of intelligent and autonomous vehicles requires enhanced vehicular services that can handle ultra-reliable situations. The DSRC has been introduced more than a decade ago, which relies on the IEEE 802.11p protocol. The DSRC is suitable for most vehicle-safety applications, vehicle traffic management, and other value-added services, such as parking and vehicle analytics. The global adoption of DSRC has been delayed due to the communication challenges that were introduced by dynamic mobility and poor scalability. Meanwhile, the 3 GPP studied the C-V2X based on LTE that provides performance advantages by leveraging the infrastructures within the eNB coverage for effective resource allocation, higher link budget, less interference, and improved Non-Line of Sight (NLoS) capabilities to overcome \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Components** & **DSRC V2X** & **Cellular V2X** \\ \hline Specification Completion & Completed & Rel.14/15 completed \& \\ \hline Technology & Wi-Fi & LTE/ 4G \\ \hline Modulation & OFDM & SC-FDM \\ \hline Retransmission & No HARQ & HARQ \\ \hline Connectivity & Hybrid mode, i.e., connects with cellular network for non-safety services & Hybrid model, i.e., connects with peer vehicles based on PC5 mode \\ \hline Network communication & Limited (Via APs only) & Full support \\ \hline Resource selection & CSMA-CA & Semi persistent Tx with comparative energy-based selection \\ \hline Line coding & Convolution code & Turbo code \\ \hline Deployment & Started in 2017. Commercialized in 2019 & Mass market distribution in China by the end of 2020 \\ \hline Future guideline & Backward compatible and interoperable upgrade to 802.11 bd & C-V2X Rel.16 based on 5G NR and operates on different channel \\ \hline Latency & Low latency for V2V communications & Round trip latency less than 1 ms, minor delay due to centralized communication \\ \hline Range & Good for short radio range & Good for extended communication \\ \hline High mobility support & Upto relative speed of 500 km/h with advanced receiver support & Up to 500 km/hr as a minimum requirement \\ \hline High density support & Packet loss at high density & No packet loss guaranteed at high density \\ \hline Security and Privacy on V2V/ V2I/V2P & Yes (based on IEEE WAVE \& ETSI ITS security services) & Yes (based on IEEE WAVE \& ETSI ITS security services) \\ \hline Security and Privacy on V2N & N/A & Yes \\ \hline Evolution path & Towards 802.11 bd & Compatible with Rel -14/15 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Detailed Comparison of DSRC based and Cellular based V2X communications. the DSRC limitation [21]. The C-V2X sidelink mode 4 performs better than DSRC with regard to higher link budgets as well as frequency re-use over a specified geo-location. However, this mode performs poorly due to the increased interference between user nodes, while reducing the reuse distance when traffic density increases. The DSRC and C-V2X are capable of providing the vehicle safety applications within the message requirements of 1 Hz to 10 Hz periodicity and end-to-end latency of 50-100 ms. However, as vehicles become more advanced and, as they evolve towards intelligent and autonomous vehicles, the QoS requirements of V2X become more stringent. Thus, the existing V2X technologies may not satisfy the performance requirement of future V2X communications. The existing V2X technologies need to evolve in order to enhance the reliability in advanced V2X use-cases for intelligent and autonomous vehicles. They should satisfy ultra-low latency, safety, and security enhancements beyond what the existing V2X applications have achieved based on basic safety applications [22].