Unmanned Aerial Vehicles (UAVs) have created new opportunities for various applications in civil airspace. One critical aspect of a successful operation is to establish reliable communication between a UAV and the remote pilot in a Ground Control Station in Remotely Piloted Aircraft Systems. The effectiveness of this communication, known as C2 communication, depends on the underlying network technology (LTE/5G, Satellite, etc.) and the specific application telemetry protocol. A single C2 link using cellular or satellite communication technology fails to satisfy the ICAO C2 performance requirements [1]. Therefore, a multi-link framework for C2 communication is widely adopted. However, the homogeneous cellular-based multi-link [2] experimental solutions have limitations concerning the geographical location of Beyond Visual Line-of-Sight (BVLOS) operations. Additionally, simulation analysis of the heterogeneous multi-link [3] solution, using cellular and GEO-satellite communication, is inadequate to conclude the link performance requirements (bandwidth and latency) for the telemetry protocol. Therefore, we propose a heterogeneous 5G and LEO-satellite Iridium multi-link network architecture for C2 communication. Our quantitative analysis of the link technology present in this architecture demonstrates (i) the required logical Link Quality Indicator for C2 communication, and (ii) the possible solutions for C2 telemetry protocol to utilize the link capabilities in this architecture. We demonstrate that a cellular link can provide a throughput of 3.5, 8.5 Mbps and 30 ms latency for 5G, whereas an Iridium satellite link can provide 22, 88 kbps (uplink, downlink) throughput and 750 ms latency sufficient for reliable C2 communication.

This paper presents the development of a laboratory demonstrator within NEWSKY, a project co-funded by the European Commission within its 6th Research Framework Programme (FP6). Host and network mobility are some of the essential network functionalities required for efficient operation of a network-centric aeronautical communication system. This paper deals with the feasibility demonstration of Mobile IPv6 (MIPv6) and Network Mobility (NEMO) protocols to suitable provide mobility support for the future Air Traffic Management (ATM) network.

This paper presents the comparison of two IPv6 over IPv4 solutions for a laboratory demonstrator within NEWSKY, a project co-funded by the European Commission within its 6th Research Framework Programme (FP6). NEWSKY aims at developing a concept for a global, heterogeneous communication network for aeronautical communications. It assumes IPv6 hosts, but nowadays satellite networks still run over IPv4 links. Two solutions have been tested and investigated over a real satellite link for this project: L2TP tunneling and NAPT-PT modified. Both are implemented and compared in terms of overhead and complexity. Results show that NAPT-PT modified adds less overhead than tunneling, however, L2TP computation is easier and faster than NAPT-PT modified.

This paper presents the development of a compact, ruggedized satellite terminal, to be used for communications in emergency situation. The terminal provides GSM coverage in disaster area, where existing communication infrastructure is destroyed or overloaded. It uses GSM backhauling over satellite to transport GSM signalling and data traffic to the core GSM network infrastructure in the disaster-safe area. Additionally, basic data services such as HTTP Web browsing and email are also provided via WiFi access. Issues related to the terminal design and the tests that have been undertaken are presented in the paper.

The paper describes some essential trends in the development of satellite communications and introduces promising future applications. Important developments are the set up of standards based on digital video broadcast (DVB) and the application of on-board switching taking into account quality of service (QoS). Other developments are the application of multiprotocol label switching (MPLS) to satellite networks and the usage of optical inter-satellite and inter-platform links. Seamless interworking with terrestrial wireless access networks and with terrestrial core networks is of paramount importance for the success of satellite networks. Future applications of satellite communications include aeronautical satellite communications, satellite-based air traffic management and personalised land mobile radio broadcasting.

Nongeostationary satellite constellations with intersatellite links are a challenge for networking due to their continuously changing topology. In order to make maximal use of the network's capacities, special attention has to be paid to routing and traffic engineering. Multiprotocol label switching (MPLS) as underlying protocol is an interesting candidate for this task since it offers many possibilities to exert influence on traffic flows and supports today's dominating Internet protocol traffic very well. This paper describes a general MPLS-based networking concept for satellite networks and discusses different scenarios considering the particularities and constraints of the dynamic topology. Functional elements of MPLS like ingress, egress, or core routers have to be mapped onto the physical entities of the network and prerequisites for traffic engineering are discussed. Routing and rerouting of paths is of key interest since this affects route computation effort and routing performance. Thus, an analytical estimation of routing effort is deduced and numerical and simulation results are presented.

The paper discusses various aspects of aeronautical broadband satellite communications (AirCom). Market issues are addressed, and a range of relevant services is identified and classified. A structured overview of key issues and respective steps for the system design of an AirCom system is given. It is intended to provide a generalized baseline for a systematic AirCom design process and reflect some recent, ongoing and planned R&D activities in the field. This overview focuses on geographic coverage, constellation candidates and crucial terminal antenna issues.

Regular mesh topologies typical for satellite communication networks comprised of intersatellite links provide high network flexibility and reliability, but due to dynamic changing of traffic load and interorbit link distance variation, adaptive routing is an absolute requirement for optimizing the network utilization. In this article, we address adaptive routing in the intersatellite link (ISL) segment of nongeostationary packet-switched satellite communication systems, focusing on the relative impacts of traffic load and propagation delay on the link cost. We consider four reference traffic flow scenarios with different levels of traffic concentration. he network performance is evaluated in terms of routing performance measures important from both the end user and the network operator perspectives. Using an ISL network simulator, we reveal some intrinsic effects of the selected constellation and effects introduced with different assumptions regarding the traffic model.

This paper outlines a methodology to estimate the bandwidth demand for a multiservice satellite system. The two basic components of the methodology are (a) an analytical estimation of single-service bandwidth demand for both FDM/TDMA and FDM/CDMA satellite systems, and (b) a general and tractable approach to system capacity dimensioning, essentially based on a new generic multiservice source traffic model. One of the key features of the multiservice model is its scalability, making it a practicable and future-proof tool in the rapidly evolving broadband communication world. Finally, a numerical evaluation of bandwidth requirements for a specified study system is provided.

Satellite systems are going to build a part of the future personal communications infrastructure. The first-generation candidates for satellite personal communication networks (S-PCN) will rely on low Earth orbit (LEO) and medium Earth orbit (MEO) constellations. A noticeable trend in this field is toward broadband services and the use of ATM. For LEO satellite systems employing intersatellite links (ISLs), this paper proposes an overall networking concept that introduces the strengths of ATM to their operation. The core of the paper is the design of a new routing scheme for the periodically time-variant ISL subnetwork, discrete-time dynamic virtual topology routing (DT-DVTR), and its ATM implementation. DT-DVTR works completely off line, i.e., prior to the operational phase of the system. In a first step, a virtual topology is set up for all successive time intervals of the system period, providing instantaneous sets of alternative paths between all source-destination node pairs. In the second step, path sequences over a series of time interval are chosen from that according to certain optimization procedures. An ATM-based implementation of DT-DVTR in LEO satellite ISL networks is presented with some emphasis on the optimization alternatives, and the performance in terms of delay jitter is evaluated for an example ISL topology.

An asynchronous transfer mode (ATM)-based concept for the routing of information in a low Earth orbit/medium Earth orbit (LEO/MEO) satellite system including intersatellite links (ISLs) is proposed. Specific emphasis is laid on the design of an ATM-based routing scheme for the ISL part of the system. The approach is to prepare a virtual topology by means of virtual path connections (VPCs) connecting all pairs of end nodes in the ISL subnetwork for a complete period in advance, similar to implementing a set of (time dependent) routing tables. The search for available end-to-end routes within the ISL network is based on a modified Dijkstra (1959) shortest path algorithm (M-DSPA) capable of coping with the time-variant topology. With respect to the deterministic time variance of the considered ISL topologies, an analysis of optimization aspects for the selection of a path at call setup time is presented. The performance of the path search in combination with a specific optimization procedure is-by means of extensive simulations-evaluated for example LEO and MEO ISL topologies, respectively.

Currently many efforts are undertaken to develop and install communication networks based on low Earth orbit (LEO) and intermediate circular orbit (ICO) satellites. However, many problems are to be solved before the final operation of such networks. This paper deals with basic design problems of LEO/ICO-based networks. The topology of the satellite network is considered and estimates for the number of satellites necessary, orbits and number of communication channels per satellite are derived. The features and consequences of intersatellite links are discussed. The number of communication channels per link is derived with a more elaborate model. This includes the radio links from the satellites to mobile users and to gateways, as well as intersatellite links and terrestrial lines. We introduce a formal model for LEO/ICO based networks and propose a method for the evaluation of the link capacities, given the network topology and the traffic requirements. As an example, two constellations are investigated in detail. One of these constellations is the Iridium system proposed by Motorola, the other is the LEONET concept developed in an ESA study. Finally, the influence of unequal traffic distribution is discussed.>

Currently, many efforts are undertaken to develop and install world-wide communications networks based on low Earth orbit (LEO) or intermediate circular orbit (ICO) satellites. However, many problems are still to be solved. One of these problems, namely the design of strategies for handover between satellites is addressed. Strategies that intend to maximize the instantaneous elevation angle or to minimize the handover rate are compared. The authors also consider not performing handovers at all. The main result is that sufficient call duration can be guaranteed without performing handovers when an intermediate orbit altitude (at about 6000 km) is chosen.>