A systematic review of green IoT technologies, communication protocols, security challenges, and applications in smart cities
摘要
The rapid urbanization and the increased need for sustainability have placed the Green Internet of Things (G-IoT) at the center as the key driver of green smart cities. In this paper, a systematic literature review (SLR) of G-IoT technologies and strategies applied in urban settings is provided following PRISMA guidelines. Integrating 130 studies from 2015 to 2025, the review consolidates findings across three interconnected areas: energy-saving technology, communication protocols, and security concerns with corresponding countermeasures. Structuring these findings, the study proposes a three-category technology model and a three-layer security framework. The review highlights the most recent advances, trade-offs, and contextual suitability of G-IoT solutions while identifying gaps that require further investigation. With the merging of these perspectives, the review presents a comprehensive understanding of G-IoT's role in improving energy efficiency, adaptability, and sustainability in smart cities as well as outlining avenues for future research towards achieving greener, adaptive urban environments.