<div>The implementation of the Internet of Things (IoT) is mostly done through cellular networks which do not cover the whole world. In addition, the explosive growth of global Internet access demand introduces the need for integrating satellites with cellular IoT networks for coverage extension and backhaul offloading. Operating hybrid satellite-IoT (SIoT) networks, however, might incur excessive service latency and high satellite bandwidth consumption. To tackle these issues, edge caching technology has been considered in SIoT. This article reviews existing research on edge caching-based SIoT networks with illustrative performance evaluation. Various caching design criteria with a focus on two-tier cache-enabled SIoT are discussed. In addition, open research problems on edge caching in SIoT are identified as future research directions and opportunities.</div>
Mobility Management in Emerging Ultra-Dense Cellular Networks: A Survey, Outlook, and Future Research Directions
