  Blockchain-based IoT systems can manage IoT devices and achieve a high level
of data integrity, security, and provenance. However, incorporating the
existing consensus protocols in many IoT systems limits scalability and leads
to high computational cost and network latency. We propose a hierar-chical and
location-aware consensus protocol for IoI-blockchain applications inspired by
the original Raft protocol to address these limitations. The proposed consensus
protocol generates the consensus candidate groups based on nodes' individual
reputation and distance information to elect the leader in each sub-layer
blockchain and uses our threshold signature scheme to reach global consensus.
Experimental results show that the proposed consensus protocol is scalable for
large IoT applications and significantly reduces the communication cost,
network latency, and agreement time by more than 50% compared with the Raft
protocol for consensus processing.
