Digital twin empowered lightweight and efficient blockchain for dynamic internet of vehicles

The Internet of Vehicles(Io V) has great potential for Intelligent Transportation Systems(ITS), enabling interactive vehicle applications, such as advanced driving and infotainment. It is crucial to ensure the reliability during the vehicle-to-vehicle interaction process. Although the emerging blockchain has superiority in handling security-related issues, existing blockchain-based schemes show weakness in highly dynamic Io V. Both the transaction broadcast and consensus process require multiple rounds of communication throughout the whole network, while the high relative speed between vehicles and dynamic topology resulting in the intermittent connections will degrade the efficiency of blockchain. In this paper, we propose a Digital Twin(DT)-enabled blockchain framework for dynamic Io V, which aims to reduce both the communication cost and the operational latency of blockchain. To address the dynamic context, we propose a DT construction strategy that jointly considers the DT migration and blockchain computing consumption. Moreover, a communication-efficient Local Perceptual Multi-Agent Deep Deterministic Policy Gradient(LPMA-DDPG) algorithm is designed to execute the DT construction strategy among edge servers in a decentralized manner. The simulation results show that the proposed framework can greatly reduce the communication cost, while achieving good security performance. The dynamic DT construction strategy shows superiority in operation latency compared with benchmark strategies. The decentralized LPMA-DDPG algorithm is helpful for implementing the optimal DT construction strategy in practical ITS.