## 3 Background and Previous Related Work
### DLT-Based ITS Related Works  
Vehicles become smarter everyday due to the advancement of transportation and communication technology [56]. The blockchain can potentially handle various IoV applications with creative solutions. Most IoV applications are real time, mobile, and generate and share large amounts of data. In IoV environments, many standard strategies may not work. In addition, increased connectivity may give malevolent actors new attack channels. Blockchain incorporation into the IoV enhances security, privacy, trust, system performance, and automation. Thus, blockchain-like robust technology should be used for flexibility and big data. We list some important incentives for IoV blockchain adoption below. To be considered a \"smart city\", a metropolis must have reliable public transportation. Due to the many factors that must be considered to ensure passenger safety, ITS is classified as a Complex Cyber-Physical System (CCPS). The term \"Internet of Vehicles\" refers to the network of vehicles that allows them to share data, conduct analysis, and deliver and receive feedback in a real-time environment [3; 4]. \begin{table}
\begin{tabular}{c c c c} \hline \hline \# & **Algorithm/Technology** & **Pros** & **Cons** \\ \hline
1. & Proof of Work (PoW) [49] & High security, Decentralization & Energy inefficiency, Scalability issues \\ \hline
2. & Proof of Stake (PoS) [50; 51] & Energy efficiency, Faster transactions & Centralization risk, Security concerns \\ \hline
3. & Delegated Proof of Stake (DPoS) [51] & High scalability, Energy efficiency & Centralization risk \\ \hline
4. & Practical Byzantine Fault Tolerance (PBFT) [52] & Fast transactions, High fault tolerance & Limited scalability, Centralization risk \\ \hline
5. & Proof of Authority (PoA) [53] & Fast transactions, Energy efficiency & Centralization risk \\ \hline
6. & Tangle (DAG-based) [54] & Scalability, No transaction fees, Energy efficiency & Vulnerable to spam attacks, Lower security guarantees \\ \hline
7. & Hashgraph [55] & Fast transactions, Fairness, Asynchronous Byzantine Fault Tolerance & Centralization risk, Licensing and patent issues \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of Consensus Algorithms and DLTs. The IoV has the potential to become the next decade's trend due to advancements in satellite communications, AI and CPS [56; 57]. The next decade will see a rise in vehicle automation and intelligence. A small number of initiatives, such as ERTICO ITS Europe and City Verve Manchester, have been launched to aid the development of ITS in smart cities. Depending on the precision of the data and the methods used to regulate traffic, a mountain of information will be generated as the number of vehicles on the road continues to swell. If the operations are conducted using the traditional IoT model, then latency, complexity, and IoV needs will be major obstacles. Compatibility and interoperability across IoV components from different service providers is extremely difficult to guarantee. Data interchange and storage infrastructure must be decentralized, distributed, interoperable, flexible, and scalable to support the growth of IoV and unlock the full potential of ITS. Data security and management, data resource and training, resource sharing, vehicle management, ride sharing, content streaming, traffic control and management, and V2V communication are all areas where DLT could serve as a platform [18]. In [58], a blockchain-based distributed ledger solution for managing data securely within the vehicle edge computing networks using a consortium blockchain was developed. There are two ways in which the use of smart contracts would improve the proposed system. As a first step, the smart contract is utilized to guarantee the integrity of data exchanged between vehicles and the edge computing servers located in vehicles. Second, the smart contract prevents unauthorized disclosure of the data. Hence, vehicles may pick the greatest and most trusted source of high-quality data.