Blockchain-based solutions for IoT: A tertiary study

The combination of blockchain and Internet of Things (IoT) brings revolutionary changes to Industry 4.0. However, blockchain technology is immature now and the combination is under exploration. To understand the research status of applying blockchain-based solutions for IoT, we conduct a tertiary study that systematically reviews secondary studies in this domain. Through the processes of automated search and selection, this study obtains 11 secondary studies published between 2016 and 2020. Based on the rigorous data extraction and analysis, we have established a comprehensive overview of the current state, concerns, and critical findings of relevant studies focusing on blockchain-based solutions for IoT. Results involve typical challenges and characteristics of blockchain itself, the constrained nature of IoT, and specific domains that blockchainbased solutions are commonly applied to. Three directions are also highlighted for future research, i.e. addressing challenging quality attributes, consensus optimization, and integrating blockchain-based IoT with other new technologies.Qianwen Xu, Xiudi Chen, Shanshan Li, He Zhang, Muhammad Ali Babar, and Nguyen Khoi Tra