MEC-Enabled Integrated Terrestrial and Non-Terrestrial Networks: A Focused Overview

The proliferation of Internet-of-Things (IoT) devices, connected vehicles, and emerging 6G services is driving unprecedented demand for ubiquitous connectivity and low-latency computing. While standalone terrestrial networks struggle to meet these requirements, Integrated Terrestrial and Non-Terrestrial Networks (ITNTN) have emerged as a unifying architecture that spans ground, aerial, maritime, and satellite segments for ubiquitous and reliable connectivity. Mobile Edge Computing (MEC) is expected to play a central role in this ecosystem by bringing computation closer to end users and enabling real-Time, computation-intensive applications. This survey provides a concise overview of MEC-enabled ITNTN, summarizing recent advances across UAV, HAPS, maritime, and satellite platforms, and examining how computing resources are distributed and coordinated across the ITNTN layers. Unlike existing surveys that treat these domains separately, this work highlights the benefits and design considerations of a fully integrated MEC-enabled ITNTN architecture. The paper concludes by outlining open issues and emerging research directions that will shape next-generation computing in ITNTN.