Space-Air-Ground Integrated Network: A Survey

TLDR

Space‑air‑ground integrated networks combine satellite, aerial, and terrestrial systems, offering new services but also facing heterogeneity, self‑organization, and resource imbalance that hinder optimal traffic delivery. This paper provides the first comprehensive survey of SAGIN, covering all three network segments rather than focusing on a single layer. The authors review recent research on SAGIN network design, resource allocation, performance analysis, and optimization, and outline existing architectures, challenges, and future research directions.

Abstract

Space-air-ground integrated network (SAGIN), as an integration of satellite systems, aerial networks, and terrestrial communications, has been becoming an emerging architecture and attracted intensive research interest during the past years. Besides bringing significant benefits for various practical services and applications, SAGIN is also facing many unprecedented challenges due to its specific characteristics, such as heterogeneity, self-organization, and time-variability. Compared to traditional ground or satellite networks, SAGIN is affected by the limited and unbalanced network resources in all three network segments, so that it is difficult to obtain the best performances for traffic delivery. Therefore, the system integration, protocol optimization, resource management, and allocation in SAGIN is of great significance. To the best of our knowledge, we are the first to present the state-of-the-art of the SAGIN since existing survey papers focused on either only one single network segment in space or air, or the integration of space-ground, neglecting the integration of all the three network segments. In light of this, we present in this paper a comprehensive review of recent research works concerning SAGIN from network design and resource allocation to performance analysis and optimization. After discussing several existing network architectures, we also point out some technology challenges and future directions.