A Latency Assessment in Blockchain-IoT Systems with Ad-hoc Routing <Abstract> Applications that ensemble IoT and blockchain have become popluar in recent years. In such applications, a blockchain is commonly deployed on top of the infrastructure-based underlying IoT network (e.g., Wi-Fi), which causes the single point of failure problem. In this paper, we consider using infrastructure-less IoT for blockchain (i.e., ad-hoc IoT-Blockchain network) to avoid the issue. Latency is one of the necessary parameters to evaluate the network quality in the ad-hoc IoT-Blockchain system. The latency is closely related to the synchronization of transactions and blocks in the blockchain. Therefore, assessing latency in an ad-hoc IoT-Blockchain network is essential. This work evaluates two latency metrics named Transaction-Oriented Latency (TOL) and Block-Oriented Latency (BOL) in an ad-hoc IoT-Blockchain system with Ethereum and two famous consensus mechanisms: Proof of Work (PoW) and Proof of Authority (PoA). We create a smart contract that transactions can trigger; we then adopt a measurement method to get latency values. The evaluation results reveal the TOL and BOL following the transaction number in both the ad-hoc IoT-Blockchain with PoA and PoW. |