Space-Air-Ground Integrated Networks for 6G Mobile Communications

TL;DR

The paper argues that Space-Air-Ground Integrated Networks (SAGIN) are essential to realize 6G through three-dimensional global coverage and unified management across space, air, and ground. It proposes design principles and a hierarchical architecture with three layers (Basic Wireless, Integrated, Exploration) and identifies key technologies to address space-ground challenges, including unified frame structures, waveform adaptation, and spectrum sharing. A case study demonstrates a Multi-routing-plane Flow Scheduling Strategy (MFSS) that leverages equivalent paths to mitigate congestion and improve throughput in SAGIN. The work underscores SAGIN's potential to extend coverage to oceans, mountains, and deserts and to support critical services, while noting ongoing challenges in synchronization, resource sharing, and mobility management.

Abstract

After the industrialization of 5G cellular communications, 6G has increasingly become a research hotspot in the academia. Space-Air-Ground Integrated Network (SAGIN) is a key supporting technology for 6G because of its advantages such as high-speed transmission and expanded coverage. This paper summarizes the motivation to develop the SAGIN-assisted 6G first and introduces the current situation of SAGIN. We then try to discuss the design concept of the SAGIN-assisted 6G, and list the problem and challenges. Moreover, we propose an architecture of the SAGIN-assisted 6G and identify a series of key technologies that are needed in different layers. Finally, in order for readers to better understand our hierarchical architecture, we use a case study discussing the congestion problem in the Integrated layer.

Figures (5)

• Figure 1: Example of Mega-constellation Leo_sat_net.
• Figure 2: An architecture of the SAGIN-assisted 6G system.
• Figure 3: Key technologies of the SAGIN-assisted 6G system.
• Figure 4: The delay of sub-optimal paths in Starlink.
• Figure 5: CDF of End-to-End Throughput.