## 2 Literature Review
### Blockchain in IoT
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Domain** & **Problem Identified** & **Proposed Solution** & **Technique** & **Results** & **Limitations** \\ \hline VN [7] & Insecure communication in large & Vehicular adhoc network for & Not explicit & Scalability of the system is achieved & Limited resource sharing scenario \\  & scale VN & Scalable VN & Not explicit & Scalability of the system is achieved & Limited resource sharing scenario \\  & & Insecure service provisioning & Secure service & Blockchain with PoA & Secure service \\  & for IoT & provisioning mechanism & consensus algorithm & provisioning achieved & Service charging is not considered \\  & & & & & \\ IoT [10] & Optimization of the & Blockchain-based hybrid & Hybrid architecture with Aggagagai & Reduction in computational time & Efficient deployment of edge node \\  & system performance & network architecture & based PW & Reduction in computational time & is not considered \\  & & & & \\ IoT [11] & Credibility verification in IoT & Blockchain-based credibility & Self organization & Response time and storage capacity & Complete decentralization is not achieved \\  & & verification method & Blockchain structure & are optimized & not achieved \\  & & & & \\ IoT [12] & Authentication of IoT & Attribute based access & Blockchain-based access & Secure access control & Users attribute execution is not considered \\  & & control mechanism & control mechanism & policies achieved & not considered \\  & & & & \\ IoT [13] & Security and authentication & Decentralized access & Blockchain and Attribute based & Scalability and robustness achieved & No real-time scenario is considered \\  & & & & \\ IoT [14] & Secure data sharing scenario & Efficient access control and & Data chain and behaviour chain is & Security and privacy preserving & Proposed system is designed only \\  & & permission levels & used for data sharing & data sharing systems & for a single system \\  & & & & \\ IoT [15] & Third party involvement & DAC & Blockchain with e-trading system & Secure trading environment & Designed only for two communities \\  & & & &  
In [17], the authors proposed a blockchain-based distributed network architecture for the Internet of Vehicles (IoV). To overcome challenges of real-time response in VN, a distributed architecture is proposed. The secure storage of big data is the main concern of blockchain-based VNs. However, the real-time traffic rate is not considered by IoV. In [18], the authors presented a blockchain-based decentralized trust management system for VN. The proposed work is aimed at maintaining trust between the vehicles. Vehicles are able to query the trust value of neighbours using Bayesian inference model. RSUs participated in the network to calculate the trust value of each vehicle. From the experimental results, it is concluded that proposed system is more efficient in terms of calculating and storing trust value. However, privacy preservation is not considered in this paper. Authors in [19] proposed a consortium blockchain-based service provisioning scheme for lightweight clients. The issue of less computational capabilities of these devices is tackled. In the proposed work, an incentive mechanism is proposed to encourage the participants. To reduce resource consumption, PoA consensus mechanism is used instead of PoW in the proposed work. The comparison between hashing algorithms is also performed to check which algorithm performed better in the proposed model. Furthermore, the service provisioning is performed at reduced cost.