Blockchain in IoT Systems: End-to-End Delay Evaluation

Providing security and privacy for the Internet of Things (IoT) applications while ensuring a minimum level of performance requirements is an open research challenge. Recently, blockchain offers a promising solution to overcome the current peer-to-peer networks limitations. In the context of IoT, Byzantine fault tolerance (BFT)-based consensus protocols are used due to the energy efficiency advantage over other consensus protocols. The consensus process in BFT is done by electing a group of authenticated nodes. The elected nodes will be responsible for ensuring the data blocks' integrity through defining a total order on the blocks and preventing the concurrently appended blocks from containing conflicting data. However, the blockchain consensus layer contributes the most performance overhead. Therefore, a performance study needs to be conducted especially for the IoT applications that are subject to maximum delay constraints. In this paper, we obtain a mathematical expression to calculate the end-to-end delay with different network configurations, i.e., number of network hops and replica machines. We validate the proposed analytical model with simulation. Our results show that the unique characteristics of IoT traffic have an undeniable impact on the end-to-end delay requirement.

I. Introduction

Internet of Things (IoT) is a paradigm that ranges from small, localized systems to large, geographically distributed systems that interconnect things to the Internet by using standard communication protocols [1]. IoT received massive attention from numerous business and technological industries that made the IoT one of the most demanded technologies of the future. However, modern IoT systems come with stringent network delay needs. Apart from this, the existing IoT systems are cloud centered. And, sending the data all the way to the cloud servers can easily break the delay requirements. Despite centralization and controlled data, cloud-supported IoT devices are not safe from cyber-crime, privacy issues, and security breaches. It is a fact that the single point of failure and the security flaws in IoT devices have placed data integrity and privacy at risk. It is shown that more than 25% of corporate attacks and cyber-crimes would be because of the compromised IoT devices [2]. It has become mandatory that the operational model of IoT devices should be shifted from over-arched centralized model to automated decentralized architecture. This transformation will help to make the IoT devices more self-regulating and autonomous.