Evaluating Impacts of Overlay Networks on IoT Blockchain Latency <Abstract> It is envisioned that the Internet of Things (IoT) will be strengthened with blockchain technology in the so-called IoT blockchain system. The IoT Blockchain system may abstract the heterogeneous IoT protocols and devices and provide blockchain benefits. Integrating blockchain with the IoT may ensure IoT data security, traceability, and integrity. This study investigates the integration of IoT with Ethereum Blockchain with private blockchain deployments. Moreover, we focus on latency performance in the IoT blockchain system. More specifically, we deploy various overlay networks in an Ethereum-based IoT system and evaluate their impact on latency, considering the Transaction-oriented Latency (TOL) and block-oriented latency (BOL) metrics. Our findings reveal that a fully connected graph does not lead to low latency, and the Barab?si?Albert (BA) model effectively mitigates latency increases due to higher transaction frequencies. This study contributes to understanding latency in private IoT Blochain with multiple nodes, emphasizing the importance of overlay network design for optimal system performance. |