ScaChain: A Hierarchical Blockchain Architecture for Scalable Data Management in IoV

In this paper, we propose a hierarchical blockchain architecture, namely ScaChain, for scalable data management in the Internet of Vehicles (IoV). ScaChain aims to enhance scalability in both storage and throughput of IoV data management. To improve storage scalability, ScaChain hierarchically stores IoV data in multiple blockchains partitioned by geographical regions. Specifically, ScaChain's hierarchical architecture consists of a cross-region chain that stores globally shared data and multiple DAG-structured intra-region chains that store locally shared data. To improve throughput scalability, we develop an adaptive throughput optimization algorithm for ScaChain based on Deep Reinforcement Learning (DRL). The algorithm maximizes throughput by adaptively adjusting blockchain configurations based on varying IoV resource conditions, while satisfying decentralization, security, and low-latency constraints. Simulation results demonstrate that our ScaChain achieves superior scalability in data storage and throughput compared to state-of-the-art blockchain architectures in the IoV.