Digital revolution is characterized by the convergence of technologies — from cloud computing to edge/fog computing, Artificial Intelligence (AI), big data, Intelligent Internet of Things (IoT), and Distributed Ledger Technology (DLT) — that is blurring the lines between physical and digital worlds. In this context, the IoT tsunami, the ubiquitous adoption of intelligent connected devices, and the public embracement of DLT, of which blockchain is a popular example, are increasingly becoming an integral feature of many modern systems, particularly, IoT-based smart and connected healthcare. Although the IoT and DLT/blockchain are two very different technologies and distinct from each other, the fusion of blockchain and IoT technologies is an unprecedented paradigm shift that is expected to disrupt both current and future systems in various fields. Blockchain has exactly what is needed to fix the weaknesses and vulnerabilities of IoT. It solves the security fault line among intelligent IoT where most of the IoT devices are connected to each other through the public trustless environment. Moreover, its distributed peer-to-peer nature can address the shortcomings of client/server models in Cloud-IoT solutions. Although the convergence of IoT and blockchain (Blockchain-IoT) can potentially tackle major shortcomings of today's solutions, its adoption is still in infancy, suffering from various issues and thus there is a necessity to address significant challenges including scalability, consensus algorithms, data privacy, efficiency, availability, storage, interoperability, and standardization, among others. In addition, there is no consensus towards any reference model or best practices that specify how blockchain should be utilized in IoT. This paper aims to present a holistic reference architecture as well as fundamentals, recent advancements, promises, and challenges in order to foster the investigations on cutting-edge research and allowing one to contribute to advancing the convergence of blockchain and IoT.

数字革命的特点是融合了技术，从云计算到边缘/雾计算，人工智能（AI），大数据，智能物联网（IoT）和分布式账本技术（DLT），这模糊了两者之间的界限物理和数字世界。在这种背景下，物联网海啸，无处不在的智能互联设备的普及以及DLT的公众拥护正日益成为许多现代系统不可或缺的特征，尤其是基于物联网的智能互联卫生保健。尽管IoT和DLT /区块链是两种截然不同的技术并且彼此不同，但区块链和IoT技术的融合是前所未有的范式转变，有望破坏各个领域的当前和未来系统。区块链正是解决物联网的弱点和漏洞所需的工具。它解决了智能物联网之间的安全故障线，其中大多数物联网设备通过公共不信任环境相互连接。此外，它的分布式对等性质可以解决Cloud-IoT解决方案中客户端/服务器模型的缺点。尽管物联网和区块链（Blockchain-IoT）的融合可以解决当今解决方案的主要缺点，但其采用仍处于起步阶段，存在各种问题，因此有必要应对重大挑战，包括可扩展性，共识算法，数据隐私，效率，可用性，存储，互操作性和标准化等。此外，对于指定应如何在物联网中使用区块链的任何参考模型或最佳实践，尚无共识。本文旨在提供一种整体参考架构以及基础知识，最新进展，希望和挑战，以促进对前沿研究的研究，并为推动区块链和物联网的融合做出贡献。