Efficient and Trusted Data Sharing in a Sharding-Enabled Vehicular Blockchain

Data sharing is essential for future autonomous vehicles in vehicular networks. Building trust in the shared data can be challenging among mutually unknown vehicles in an open and distributed environment. Blockchain is the key to establish trusted data sharing in a decentralized vehicular environment. However, the low efficiency (e.g., transaction per second, TPS) of blockchain is the bottleneck for the efficient data sharing. Moreover, the highly dynamic topology, the imperfect wireless links, and the limited radio coverage may further slow down the blockchain consensus process. To improve the efficiency and trustworthiness of data sharing in a vehicular network, we propose a sharding-enabled vehicular blockchain system. Specifically, the blockchain-enabled vehicles are dynamically allocated to different shards based on their geographical locations so that transactions are processed in parallel. We design an efficient and trusted sharding-enabled blockchain consensus mechanism by integrating a reputation-assisted intra-shard consensus and a vehicle-assisted inter-shard consensus. The reputation assistance in intra-shard consensus is designed to defend against the collusive false-block attack that may happen in a small-scale shard environment. The vehicle-assisted inter-shard consensus is designed to tackle the issues caused by defective roadside units (RSUs). Simulation results demonstrate the improved performance on efficiency and trustwor-thiness of the proposed system. In addition, trusted data sharing can be established even under the conditions of malicious vehicles or attacked RSUs.