Blockchain based Message Dissemination in Vehicular Ad Hoc Networks

Abstract

Vehicular Adhoc Networks (VANETs) is a promising research interest in the field of wireless networks. It is an application of the principle of Mobile Adhoc Networks (MANETs). It is used to provide services such as road safety, navigation, traffic monitoring etc. The continuously changing topology of the network introduces challenges in implementing VANET. Resolving these challenges following different strategies introduces other trade-offs. One of the most important applications in VANET is to disseminate incident messages to nearby vehicles. The effectiveness of the application depends on the correctness of the incident message and its timely delivery to the vehicles. Blockchain is one of the mechanisms that can be used in this respect. Consensus mechanism is used to validate the message and then a proper forwarding mechanism is used to disseminate the message. An incentive mechanism is used to encourage honest behaviour of the nodes. The prominent consensus mechanisms used in blockchain such as Proof of Work (PoW), Proof of Stake (PoS), Proof of Elapsed Time (PoET) are not suitable to be used in VANET in their basic form. For example, PoW is highly time consuming and PoS is biased. Among the existing ones Practical Byzantine Fault Tolerant (PBFT) is the most suitable one for blockchain based VANET. So in our thesis we propose a new consensus mechanism which is a hybrid of the best practices of PoW and PBFT. It includes selective voting mechanism with weighted values for faster and more accurate validation. The threshold values are updated whenever needed. Limiting the number of voters makes the entire process efficient. The challenges in this respect are handled by imposing proper conditions on the voters. The concept of weighted sum of votes is introduced where honest voters are prioritized over others which results in higher accuracy in message validation in shorter amount of time. Efficient selection of relay nodes ensures minimum latency in the dissemination process by ensuring minimum number of messages are passed. It also ensures quality of the message being passed. Along with the consensus mechanism we also present a mechanism to select relay nodes which will give the best performance in the message dissemination process by selecting node that will cover the maximum possible distance. The selected nodes spread the message to the maximum number of vehicles with the minimum number of broadcast messages. The ii Abstract iii forwarding process is continued until a threshold is reached. An incentive mechanism based on both reputation and monetary units is also proposed which will encourage integrity and honest behaviour from the vehicles. Previous works show the success of incentive mechanism based on both reputation and monetary units over the ones based on only one of them. We also integrate the concept of reputation in the validation process to increase its importance. The simulation is done in the Omnet++ simulator platform integrated with Sumo. We showed the analysis of the results obtained from the simulation. The results give impressive improvements from the existing systems