A Systematic Review of Energy-Efficient Routing Protocols for IoT Networks

With the proliferation of the Internet of Things (IoT) in areas like healthcare, smart cities, and industrial automation systems, one herculean task that has been looming and must be addressed is the need to ensure that data transmission is energy-efficient because all IoT devices have limited resources. This article is a systematic literature review (SLR) of energy-efficient routing mechanisms designed to be used in IoT networks, and it focuses on comparing the energy-efficient routing schemes concerning their energy consumption, latency, and security parameters. The research protocol compiled 32 peer-reviewed scientific articles published between 2017 and 2025, following PRISMA guidelines and with strict inclusion and exclusion criteria. The results reveal that popular protocols like RPL, LEACH, TEEN/APTEEN, or AI-based solutions reflect different trade-offs. The cluster-based and chain-based approaches are known to minimize the energy consumed. In contrast, the hybrid protocols and the AI-based approaches provide trade-offs in optimizing the energy, delay, and security parameters, at the expense of complexity. The review also points out that there is a serious gap in the observance of integrated security mechanisms in numerous energy-oriented protocols. These results indicate that routing techniques that are adaptive and context-sensitive are required to comprehensively treat performance limitations of IoT. Researchers and practitioners who are interested in finding an optimal protocol choice and matching diverse IoT applications can draw important thoughts from the paper.