IEEE Network • January/February 2019
22
0890-8044/19/$25.00 © 2019 IEEE
AbstrAct
A space and terrestrial integrated network (STIN)
converges satellite communication networks,
mobile wireless networking, and the Internet,
has greatly extended the scope of cyberspace.
The STIN is composed of diverse network ele-
ments and supports various access technologies,
and the coordinations in the hybrid networks can
better support complex and changeable com-
munication tasks. Furthermore, the STIN takes
advantage of the merits of low delay and large
bandwidth in terrestrial networks, and achieves
global coverage without the limitation of geo-
graphic conditions, which can support posi-
tioning and navigation, emergency relief, space
exploration, and so on. However, the research
on STIN is still confronted with some fundamen-
tal challenges including time-varying network
topology, high satellite mobility, large end-to-end
delay, scalability, and so on. In this article, we
present a composite architecture that integrates
space and terrestrial network components for
providing anytime anywhere communications
by utilizing the software defined networking and
mobile edge computing paradigms, which not
only facilitates the network management and
increases network flexibility, but also provides
improved quality of service for global multime-
dia services. Additionally, we identify a number
of challenging issues associated with the pro-
posed STIN architecture, including mobility man-
agement, resource management, routing, traffic
steering, security, and so on, and pinpoint some
potential solutions accordingly.
IntroductIon
With the ever more rapid development of eco-
nomic globalization, traditional terrestrial net-
works have been unable to meet the needs of
long-distance global communications, since it is
difficult for them to fully cover some complex
terrains such as mountains and oceans. In addi-
tion, natural disasters (earthquakes, hurricanes,
etc.) often cause damage to the terrestrial net-
work infrastructures and interrupt continuous
end-to-end communications. Recently, with the
development of space communication technol-
ogies, a number of satellite-based commercial,
civil, and military services, including weather
reporting, disaster relief, localization and nav-
igation, space exploration, and so on, have
become more and more prosperous [1]. Satel-
lite networks not only provide communication
services to aircraft, ships, and ground mobile
phones, but also bring great convenience to per-
sonal communications. Satellite communications
enable people to obtain real-time international
and domestic information, and have become an
indispensable part of human daily life in cities
and even in rural areas.
On the other hand, satellite networks can be
expanded by inter-connecting terrestrial networks
(e.g., WiFi, 5G, LTE), which supports communica-
tions in the non-line-of-sight environments inside
buildings where users cannot easily receive satel-
lite signals. The communication architecture inte-
grating various access networks over the space
and the ground is characterized by large band-
width capability and multi-level access, and can
adapt to complex and highly dynamic commu-
nication environments. As a result, the increas-
ingly important space and terrestrial integrated
networks (STINs) can feasibly provide anytime
anywhere seamless communications for global
multimedia services with diverse quality of service
(QoS) requirements.
However, it is a nontrivial task to construct and
manage an efficient STIN, since it is confronted
by some fundamental challenges, for example,
high bit error rate, long propagation delay, and
intermittent connectivity [2]. In the space domain,
the network topology is time-varying due to either
the change of inter-satellite distance or handover.
For example, the relative speeds of satellites of
the same orbit change slowly and can be ignored,
but the relative speeds of the satellites in differ-
ent orbits may be large, which leads to frequent
link disconnections. Consequently, the traditional
terrestrial network architecture based on fixed
topology cannot be transplanted to the space
network. The unstable topology and multi-layer
communications in a STIN demand improved net-
work architecture, resource management, routing,
and forwarding strategies of both mobile nodes
in space and fixed nodes on the ground, which
greatly affects the performance of the network
such as transmission delay, the number of routes,
access control, and addressing.
Software defined networking (SDN) is char-
acterized by the decoupling of the control plane
and data plane [3]. An SDN controller has a glob-
Software Defined Space-Terrestrial Integrated Networks: Architecture, Challenges, and
Solutions
Yuanguo Bi, Guangjie Han, Shuang Xu, Xingwei Wang, Chuan Lin, Zhibo Yu, and Peiyao Sun
SPACE AND TERRESTRIAL INTEGRATED NETWORK: EMERGING
RESEARCH ADVANCES, PROSPECTS, AND CHALLENGES
Digital Object Identifier:
10.1109/MNET.2018.1800193
Yuanguo Bi, Shuang Xu, Chuan Lin, Xingwei Wang, Zhibo Yu, and Peiyao Sun are with the School of Computer Science and Engineering, Northeastern University;
Guangjie Han (corresponding author) is with the Key Laboratory for Ubiquitous Networks and Service Softwore of Liaoning province, School of Software,
Dalian University of Technology.