UE Context Dissemination in Sparse LEO Constellations for 5G/6G Cellular IoT in Store and Forward Operation

The rapid expansion of the Internet of Things (IoT) highlights the need for ubiquitous connectivity, especially in remote and underserved areas. As a cornerstone of current 5th Generation (5G) cellular IoT networks, Narrowband IoT (NB-IoT) supports diverse massive Machine-Type Communications (mMTC) applications. With mMTC expected to remain integral to future 6th Generation (6G) standards, satellite-based Non-Terrestrial Networks (NTNs), particularly Low Earth Orbit (LEO) constellations, offer a practical solution for addressing connectivity gaps in delay-tolerant IoT scenarios. This paper investigates the architecture and operational dynamics of sparse multi-satellite LEO constellations that employ store and forward mechanisms, which become essential when continuous end-to-end connectivity is unfeasible. Effective User Equipment (UE) context dissemination among satellites is a key requirement in such constellations to maintain sufficient service levels. We present an enhanced architecture that contains the mechanisms for UE context dissemination and investigate key performance metrics, such as revisit times and end-to-end delays for data transmission. Our findings indicate that multi-satellite configurations are crucial in providing sufficient service levels to UEs, particularly in sparse constellations. Moreover, we demonstrate that, depending on the revisit time requirements, dissemination among a subset of satellites is sufficient, albeit with an increase in end-to-end delays for data transmissions.