A Hierarchical Blockchain Framework for Fog Computing-supported IoT Networks

Abstract

Blockchain has been recently extended into Internet-of-Things (IoT) networks to further improve security and reliability of data communication. Modern IoT networks need to support a wide range of services with various requirements in terms of data delivering security, reliability, and timeliness. In this paper, a fog computing-supported hierarchical blockchain network framework is proposed. In the first layer, the Inter-Planetary File System is used to store the message uploaded by IoT devices. In the second layer, a set of subchains that are referred as channels are designed. Fog nodes subscribed to the same channel maintain the corresponding distributed ledger, and each channel support a specific IoT service. The security, latency, and communication cost of the proposed framework are derived. Besides, tradeoffs among the above three performance metrics are analyzed. Finally, a real deployment scenario based on the actual base station locations in Dublin is considered to evaluate the proposed framework. Numerical results show that it is impossible to optimize all the performance metrics at the same time. By carefully selecting the parameters of different “channels”, the proposed framework can support highly diversified services without sacrificing security.