Internet over satellites has been a hot research topic for some times. In addition to the development of the Internet applications and services over satellite, there are also significant developments in satellite communication systems and networks with Ka band and high throughput satellites (HTS).These developments enhance greatly the role of satellite in the global Internet infrastructure to allow the satellite to support broadband Internet and services beyond coverage of terrestrial networks, such as air, sea and space an addition to the land with most of the populations.

Space Internet is based on deploying many satellites with different types of earth orbits, which are capable of providing high data rates up to Gigabit/s even Terabit/s. To satisfy communication requirements of different users, it is important to develop Space Internet techniques to complement cellular and WiFi networks with satellites or unmanned aerial vehicles for global coverage of the remote areas of oceans,high mountains and desert as well as the future space missions. So, key technologies of improving the performance of Space Internet or satellite communication systems are important areas for research. This special topic issue intends to promote and expose these research activities.

The first paper, “Steady-state performance evaluation of Linux TCPs versus TCP Wave over leaky satellite links,” is authored by Ahmed Abdelsalam, et al. This paper discusses the main challenges in performance enhancement protocol(PEP) solutions for TCP wave. It also discusses relevant research activities. Simulation techniques are used for evaluations of the protocol and demonstrated its advantages.

The second paper, “Non-Orthogonal Multi-carrier Transmission for Internet via Satellite,” is authored by Yang Yang,et al. This paper takes into account integration of air interface for 5G system and satellite communication systems, and discusses GFDM based transmission scheme and its application in future Internet via satellite systems as potential air-interface technology, especially focuses on the implementation of GFDM and the novel receiving algorithm with low complexity. Simulation results demonstrate the effectiveness of the transmission scheme.

The third paper, “Statistical Modeling of the High Altitude Platform Dual-Polarized MIMO Propagation Channel,”is authored by Mingchuan Yang, et al. This paper discusses dual-polarized MIMO channel between High Altitude Platform (HAP) and high speed trains, and proposes a novel channel model, considering both Doppler shift and temporal correlation. Furthermore, HAP MIMO channel are provided.HAP is one kind of space nodes, and can be used in the future Space Internet.

The last paper, “A Power Reduction Method for Pilot Channel of LEO Satellite Based on Dynamic Compensation,” is authored by Yong Zhang, et al. This paper discusses power control for pilot channel in LEO satellite system, and proposes a power reduction scheme while keeping good performance of receiver in lower SNR. To overcome performance degrading caused by high dynamic characteristic of LEO satellite, a dynamic compensation module is added to carrier tracking loop against the high dynamic. The transfer function of new tracking loop and the condition for steadystate zero error are deduced.

The guest editors would like to take this opportunity to thank all the authors for their contributions and also thank the reviewers for their professional comments and diligent work. Their professional opinions are the key to ensure this Special Topic Issue in high quality.

Biographies

Zhili Sun,is chair of communication networking at the Institute for Communication Systems (ICS), formerly the Centre for Communication Systems Research (CCSR), University of Surrey, UK. He received his BSc in mathematics from Nanjing University, China, in 1982. He received his PhD in computer science from Lancaster University, UK,in 1991. From 1989 to 1993, he worked as a postdoctoral research fellow at Queen Mary University of London (QMUL). He has worked as principle investigator and technical co-coordinator on many projects funded by the European framework programs, the UK Research Councils, and within industries. He has published more than 125 papers in international journals and conference proceedings and book chapters. He was the sole author of “Satellite Networking - Principles and Protocols, 1st & 2nd editions”, published by Wiley in 2005 and 2014 respectively. He was a contributing editor of “IP Networking over Next Generation Satellite Systems”, published by Springer in 2008. He was also contributing editor of the textbook “Satellite Communications Systems: system, techniques and technology, 5th edition”, published by Wiley in 2009. His research interests include wireless and sensor networks, satellite communications and networks, mobile operating systems, Internet protocols and architecture,clod computing, SDN, multicast, and security.