  Blockchain technology has gained increasing popularity in the research of
Internet of Things (IoT) systems in the past decade. As a distributed and
immutable ledger secured by strong cryptography algorithms, the blockchain
brings a new perspective to secure IoT systems. Many studies have been devoted
to integrating blockchain into IoT device management, access control, data
integrity, security, and privacy. In comparison, the blockchain-facilitated IoT
communication is much less studied. Nonetheless, we see the potential of
blockchain in decentralizing and securing IoT communications. This paper
proposes an innovative IoT service platform powered by consortium blockchain
technology. The presented solution abstracts machine-to-machine (M2M) and
human-to-machine (H2M) communications into services provided by IoT devices.
Then, it materializes data exchange of the IoT network through smart contracts
and blockchain transactions. Additionally, we introduce the auxiliary storage
layer to the proposed platform to address various data storage requirements.
Our proof-of-concept implementation is tested against various workloads and
connection sizes under different block configurations to evaluate the
platform's transaction throughput, latency, and hardware utilization. The
experiment results demonstrate that our solution can maintain high performance
under most testing scenarios and provide valuable insights on optimizing the
blockchain configuration to achieve the best performance.
