Decentralizing the Internet of Things: A Systematic Exploration of Blockchain Integration, Architectures, and Cross-Domain Applications

Abstract

The proliferation of Internet of Things (IoT) devices presents new issues in the areas of security, trust, and scalability for centralized infrastructures. The scope of this paper is a systematic literature review of the usage of blockchains to solve these issues by abandoning the centralized architecture of IoT environments. 87 articles were collected within the time scope 2015–2026 under the PRISMA protocol. Of these, 52 papers were analyzed, and this work highlights five types of blockchain-IoT integration architectures: namely, full blockchain integration, hybrid cloud-blockchain integration, fog/edge blockchain integration, consortium blockchain integration, and sidechain architecture integration. This work also proposes a new layer of IoT and blockchain integration, comprising an IoT device layer, gateway/edge layer, smart contract layer, blockchain network layer, and application layer. Future research issues include healthcare, fintech, smart agriculture, industrial IoT, supply chain management, smart cities, and decentralized vehicle authentication. Finally, this work finds that blockchain integration leads to integrity, trustworthiness, and security improvement, but is accompanied by delay and computational burden; however, new issues such as light-weighted consensus, artificial intelligence and blockchain, and regulation remain to be addressed.