Feasibility Study of Function Splits in RAN Architectures with LEO Satellites

TL;DR

This study evaluates the feasibility of RAN function splits in LEO satellite-based NTN architectures, analyzing latency, bandwidth, and handover performance to inform future RAN design in satellite networks.

Contribution

It provides a comprehensive assessment of RAN function split options in LEO satellite networks, highlighting constraints, performance trade-offs, and potential benefits for NTN RAN architectures.

Findings

Low Layer Splits face strict latency constraints, causing longer mobility delays.

Onboard satellite gNodeB reduces control traffic over feeder links.

LLSs require minimal onboard processing, lowering satellite payload weight.

Abstract

This paper explores the evolution of Radio Access Network (RAN) architectures and their integration into Non-Terrestrial Networks (NTN) to address escalating mobile traffic demands. Focusing on Low Earth Orbit (LEO) satellites as key components of NTN, we examine the feasibility of RAN function splits (FSs) in terms of fronthaul (FH) latency, elevation angle, and bandwidth (BW) across LEO satellites and ground stations (GS), alongside evaluating performance of Conditional Handover (CHO) procedures under diverse scenarios. By assessing performance metrics such as handover duration, disconnection time, and control traffic volume, we provide insights on several aspects such as stringent constraints for Low Layer Splits (LLSs), leading to longer delays during mobility procedures and increased control traffic across the feeder link in comparison with the case when gNodeB is onboard satellite. Despite challenges, LLSs demonstrate minimal onboard satellite computational requirements, promising reduced power consumption and payload weight. These findings underscore the architectural possibilities and challenges within the telecommunications industry, paving the way for future advancements in NTN RAN design and operation.