Showing papers in "International Journal of Satellite Communications and Networking in 2013"

A survey of architectures and scenarios in satellite-based wireless sensor networks: system design aspects

Abstract: This paper is not a survey related to generic wireless sensor networks (WSNs), which have been largely treated in a number of survey papers addressing more focused issues; rather, it specifically addresses architectural aspects related to WSNs in some way connected with a satellite link, a topic that presents challenging interworking aspects. The main objective is to provide an overview of the potential role of a satellite segment in future WSNs. In this perspective, requirements of the most meaningful WSN applications have been drawn and matched to characteristics of various satellite/space systems in order to identify suitable integrated configurations. Copyright © 2012 John Wiley & Sons, Ltd.

A simple key agreement scheme based on chaotic maps for VSAT satellite communications

Abstract: Security is an essential requirement in any data communication system because a cyber criminal might try to break into it at any point by any means possible A key agreement procedure is a necessary technique to ensure the security of data communication by way of encryption and mutual authentication This article proposes a simple key agreement scheme on the basis of chaotic maps for VSAT satellite communications The new scheme keeps the advantages of all chaotic maps-based public key cryptosystems, providing a secure function of session key agreement Based on the intractability of chaotic map discrete logarithm problem and chaotic map Diffie–Hellman problem, the security of this new scheme has been proven to be robust enough against all the well-known cryptographical attacks with perfect forward secrecy provided In addition, compared with similar schemes that serve the same purposes, the proposed scheme demands a lower computation cost With all the previous features put together, the proposed scheme is extremely suitable for the use in very small aperture terminal satellite communication environments Copyright © 2013 John Wiley & Sons, Ltd

Cooperative strategies in satellite assisted emergency services

Abstract: SUMMARY This paper deals with the cooperative strategies, which can be adopted in emergency scenarios by integrating space and terrestrial segments, and communication and localization services. First, the cooperative solutions for integrated Navigation and Communication systems are reviewed and an effective software-defined radio implementation is described. Then, cooperative systems for broadcast and multicast communications in Incident Area Network are proposed and evaluated: in the broadcast scenario, low-complexity relaying techniques are adopted to overcome the propagation impairments and the performance degradation; in the multicast system, radio resources management techniques for group communications are designed to allow the efficient use of scarce resources and improve connectivity and reliability of the overall system. The technical solutions have been studied and tested in the framework of the Italian National Research Project SAtellite-assisted LocalIzation and Communication system for Emergency services [1]. Copyright © 2013 John Wiley & Sons, Ltd.

Satellite constellation of MEO and IGSO network routing with dynamic grouping

Abstract: Because inter-satellite links (ISLs) among the distributed satellite nodes can be used to support autonomous control in satellite system operation to reduce dependency on the ground stations, it becomes a popular communication paradigm for the future satellite systems. However, this introduces great technical challenges, particularly for routing protocol to support such space communication system. Facing the challenges, we present out study of routing technology in this paper tailored for satellite network of MEO (Table 1) and IGSO with ISLs in addition to satellite-ground links. The study aims to explore the routing strategies and algorithms of satellite network based on the evolution law of network topology to provide reference design for data exchange in autonomous satellite system. A comprehensive investigation, ranging from the analysis of relevant factors affecting data exchange in satellite networks to the primary application and resource constraints in designing satellite routing strategy, has been conducted. Our main contribution is to propose an on-demand computing and caching centralized routing strategy and algorithm on the satellite network. The routing strategy and algorithm is designed for satellite network topology dynamic grouping. The route calculation for user data transmission is divided into three phases: direction estimation, direction enhancement, and congestion avoidance. The strategy and algorithm provide significant advantages of high efficiency, low complexity, and flexible configuration, by which the satellite networks can provide the features of flexible configure, efficient transferring, easy management, structural survivability, and great potential in scalability. Copyright © 2013 John Wiley & Sons, Ltd.

Soft-decision demapping algorithm with low computational complexity for coded 4 + 12 APSK

Abstract: SUMMARY This paper proposes a soft-decision demapping algorithm with low computational complexity for coded 4 + 12 amplitude phase shift keying in an additive white Gaussian noise channel. The proposed algorithm requires only a few summation, subtraction, and multiplication operations to calculate the log likelihood ratio value of each bit, and shows the same error performance as a conventional max-log algorithm. Copyright © 2013 John Wiley & Sons, Ltd.

Dynamic uplink frame optimization with adaptive coding and modulation in DVB‐RCS2 satellite networks

Abstract: SUMMARY In the current generation of satellite networks, modulation and coding schemes can be dynamically changed in real-time to face different link conditions. Therefore, the link budget is not anymore required to be computed under the worst case, with relevant advantages in terms of efficiency. The new digital video broadcasting-return channel via satellite 2 standard extends the dynamic modulation and coding to the return link: by using different modulation and coding schemes within the uplink frame, the terminals experiencing good link conditions transmit at very high bitrates, whereas the terminals experiencing fade events transmit at lower bitrates. This paper addresses the problem of optimizing the uplink frame modulation and coding schemes based on the current link conditions experienced by the terminals and on their transmission capacity requirements. The problem is formulated as an Integer Program and an efficient Linear Program approximation is proposed. Simulation results validate the proposed approach. Copyright © 2013 John Wiley & Sons, Ltd.

DVB‐RCS2 overview

Abstract: SUMMARY This paper presents an overview, status, key technologies, and main benefits of DVB-RCS2, as well as the target goals of what is probably the largest standardization effort conducted for satellite communication systems. In addition to the novel technology elements overview and to appreciate the background, basis, and mechanisms involved, we highlight the process and the key research investigations that characterized the standardization effort. We offer a brief comparison with the first-generation DVB-RCS, and we highlight the various profiles for different target use cases and include the latest status of the mobile and mesh capabilities. Finally, we describe the structure of the standard and allow ourselves to share some thoughts of the impact it may have. Copyright © 2013 John Wiley & Sons, Ltd.

Cyclic redundancy check-based detection algorithms for automatic identification system signals received by satellite

Abstract: This paper addresses the problem of demodulating signals transmitted in the automatic identification system. The main characteristics of such signals consist of two points: (i) they are modulated using a trellis-coded modulation, more precisely a Gaussian minimum shift keying modulation; and (ii) they are submitted to a bit stuffing procedure, which makes more difficult the detection of the transmitted information bits. This paper presents several demodulation algorithms developed in different contexts: mono-user and multi-user transmissions, and known/unknown phase shift. The proposed receiver uses the cyclic redundancy check (CRC) present in the automatic identification system signals for error correction and not for error detection only. By using this CRC, a particular Viterbi algorithm, on the basis of a so-called extended trellis, is developed. This trellis is defined by extended states composed of a trellis code state and a CRC state. Moreover, specific conditional transitions are defined to take into account the possible presence of stuffing bits. The algorithms proposed in the multi-user scenario present a small increase of computation complexity with respect to the mono-user algorithms. Some performance results are presented for several scenarios in the context of the automatic identification system and compared with those of existing techniques developed in similar scenarios.

Introduction Special Issue on DVB‐RCS2

Abstract: INTRODUCTIONDVB-RCS is really the first and only broadband satellite communications standard. With workstarted already in 1998 and the first version approved in the DVB project already in 1999—10years ago—we are already talking of a mature technical specification. At the time the focus wason ATM to the desktop, Ka-band systems and large low-earth-orbit satellite constellations; orat least a lot of the community interest; and systems were proposed with several hundredsatellites. In ETSI there were two alternative specifications published at the time for mobilesatellite services based on GSM; these were the so-called GMR-1 and GMR-2 specification—both basically connected to one system each and one (or a few) vendors each.But, at the time there was also an increasing focus on standards. ETSI had just called forexperts to the Broadband Satellite Multimedia Specialist Task Force—STF BSM, and as a resultof this work established the BSM Work Group. ETSI was also the focus for the regulatory-oriented telecommunications specifications—the so-called ‘harmonized standards’ that describea way—in practice the only practical way—satellite terminals (or other telecommunicationsterminals) could comply with the new RTTEthus, the amountofnoise one could allow intoother bands or orbital locations. Article 3.2 of the RTT&E directive also had a clause stating thatwhile standards were not mandatory, stated that the communications interface should bepublished. While some argued that this meant the input and output interfaces—could both be IPfor instance—others believed that it was the air interface such as the GSM system that wasmaking world-wide success at the time (and still is). Whatever one might have believed—the factremains that DVB-RCS is just such an interface and it is published.At that time, a decade or so ago, there was also a major interest in the 2.5GHz of Ka-bandspectrum that was being made available for satellites. While not all of it would be for userterminals, some was reserved, for example, up- and downlink from gateways, it was still considered

An investigation on TCP large initial window

Abstract: SUMMARY Transport layer implicates a position where satellite networks form one integrated component of hybrid Internet architecture in today's advance technology. However, the Internet has emerged with an important new class of applications that exhibits significant variations of transmission rate over time. Variable-rate traffic poses a new challenge for transmission control protocol that provides congestion control, especially for applications that need to share the limited capacity of a bottleneck over a long delay Internet path (e.g. paths that include satellite links). Variable-rate traffic can be produced by persistent transmission control protocol connections and can be impacted by the initial window at the start or during the restart of a session. Current transport research issues are identified related to larger initial window to highlight the expected performance benefits and derive the implications on the design of geostationary satellite Internet systems as the network evolves toward a next-generation Internet. Copyright © 2013 John Wiley & Sons, Ltd.

Continuous phase modulation for broadband satellite communications: design and trade-offs

Abstract: SUMMARY In this paper, we introduce the continuous phase modulations mode of the second-generation broadband satellite communications return link Digital Video Broadcast Interactive Satellite System standard. Starting from a detailed discussion about the impairments faced in a typical broadband satellite system user set-up, we introduce the waveform selection rationale, the design trade-offs, and the waveform performance under realistic system assumptions. We show that the designed continuous phase modulations mode exhibits an excellent trade-off between performance and robustness to nonlinear distortions at low and medium spectral efficiency thus suggesting its adoption for the consumer market profile of the Digital Video Broadcast Interactive Satellite System. Copyright © 2013 John Wiley & Sons, Ltd.

A flexible QoS architecture for DVB-RCS2

Abstract: SUMMARY This paper presents a QoS, architecture for the Higher Layers Satellite in the second generation Digital Video Broadcasting with Return Channel via Satellite standard. It describes the flexibility offered by integrating link and network functions to support internet protocol-based differentiated QoS. The operation of key mechanisms is outlined and analysed to show how these may be combined to realise differentiated services by defining mappings between per-hop behaviours, to queues in the traffic plane and return channel satellite terminal request classes in the control plane. Simulation is used to show that an appropriate mapping can be used to can tune the offered service to different traffic classes and that an appropriate assignment can significantly improve the satellite bandwidth efficiency and/or the performance/QoS supplied to a traffic class. Copyright © 2013 John Wiley & Sons, Ltd.

A mathematical theory of de-integrating long-time integrated rainfall statistics. Part II: from 1 day to 1 minute

Abstract: SUMMARY We have developed, tested and discussed a theory for de-integrating the probability distribution (PD) of the daily rain rate to the PD of the rain rate integrated in 1 min, through many simple steps, with a good or very good precision, for a large range of probabilities and in many sites. The theory can also estimate the number of rain events (in the sense of rainstorms), NR, their average duration and the (conditional) PD of daily rainy time. The theory needs only three inputs, measured on site: the daily rain rate PD, the number of rainy days, ND (only for finding NR) and the PD of the rain rate integrated in two consecutive and disjoint couples of days. The theory contains two complementary parts, both successfully tested: the first deals mainly with duration of daily rainy time and rain events, and the second deals with the main issue, namely de-integrating daily rain rate PDs in 1-min PDs. We have tested the theory on duration of rainy time in Spino d'Adda, Gera Lario, Fucino and Prague and subsequently with real (blind) field tests in Milan, Lugano, many sites in the USA, and Canada. The sites tested belong to very different climatic regions. Nevertheless, the predictions are generally very close to the experimental data. The theory, and its powerful predictions, can be useful for several research communities: radio propagation, agriculture, climatology, hydrology and applied meteorology. For all disciplines and applications, seasonal studies or even monthly studies could be pursued because the data banks available can be very large, even for restricted sub-data banks. The theory will estimate its parameters on on-site seasonal, or monthly, measurements. Future developments could deal with de-integrating large-area and long-time integrated rain rate, observed by means of meteorological satellites, for obtaining ‘point’ 1-min rain rate PDs concerning a small homogeneous area. We have tested the theory to sites with very different climates and for latitudes between 65°N and 28°N. Therefore, we think that the theory can be applied globally in this latitude range because its parameters are derived from local measurements and, perhaps, down to the tropics. Because of the simplicity of the theory, and its use of few local measurements, it may be applied also to equatorial sites. This, however, is only a conjecture because we have not tested the theory directly there. Copyright © 2013 John Wiley & Sons, Ltd.

Three-dimensional radiation pattern measurement strategy for ground station antennas

Abstract: This article describes how to measure a three-dimens ional antenna radiation pattern and the most effective method to achieve this. We present a new automated three-dimensional measurement scheme, inspired by the seed pattern of a sunflower seed head, where the seed placements are arranged in a way so that rotational symmetry is obtained to compromise the circular shape of a dish antenna radiation pattern in the three-dimensional space. This new AU–TUM Antenna Radiation Measurement Strat egy has produced superior results. It has been shown by this scheme that for instance the three-dimensional transmission pattern of a dish antenna can be measured automatically and easily checked against present regulations. The generic AU–TUM Antenna Radiation Measurement Strategy was verified on a 4.8-m Ka-band dish antenna. It was concluded that a three-dimensional radiation pattern can be measured two to thirteen times faster than the best performing current strategies.

Design of the DVB-RCS2 higher layer satellite architecture

Abstract: SUMMARY This paper describes the design of the higher layer architecture for the next generation of digital video broadcasting return channel via satellite transmission systems. This is the first open standard that specifies internet protocol (IP)-level functionality. An open IP-based architecture has resulted in a competitive standard that can provide consumer and professional users with a range of IP-based interactive applications. The paper describes key aspects of the architecture and identifies a set of enhancements/adaptations to the IP protocols and techniques to ensure good performance and still efficient use of satellite bandwidth. Copyright © 2013 John Wiley & Sons, Ltd.

Security in DVB‐RCS2

Abstract: SUMMARY This paper presents security features in the second generation digital video broadcasting with return channel via satellite standard (DVB-RCS2). The up-front consideration of security, and in particular transmission security (TRANSEC), started with the development of security requirements introduced in the DVB-RCS Next Generation (NG) Commercial Requirements and Call for Technologies. It was apparent at an early stage that no single approach or implementation would satisfy the wide range of product and security requirements to span consumer, professional and government market sectors. This led to the introduction and development of two important concepts: TRANSEC profiles, a specialization of DVB-RCS2 system level profiles concept; and TRANSEC ‘hooks’, extension points that allow TRANSEC functionality to be added as necessary, governed by profile security requirements. The bulk of this paper outlines and describes the three TRANSEC profiles presented in the DVB-RCS2 Lower Layer Guidelines document. Finally, the various profiles are compared and contrasted. Copyright © 2013 John Wiley & Sons, Ltd.

A seamless soft handover management scheme in NGEO satellite networks

Abstract: SUMMARY Satellite networks can provide extensive geographic coverage to diverse user population, but handovers of active communications should be controlled considering the satellites' high speed. Mobile IP and many other handover algorithms have been proposed for terrestrial wireless networks. However, the satellite network exhibits several unique features compared with the terrestrial wireless networks, such as the long delay. This paper proposes a seamless soft handover scheme (S2H) for satellite networks. S2H designs an identity locator split addressing to solve the multihoming problem and applies the network coding scheme during handover. This manner is able to reduce the interference opportunity, save transmissions, and achieve low handover delay, short queue length, and high throughput. Relying on the simulation results, S2H is able to achieve better performance compared with the proposed handover algorithms in the satellite environment when there are multiple traffic flows. Copyright © 2013 John Wiley & Sons, Ltd.

Deploying Internet Protocol Security in satellite networks using Transmission Control Protocol Performance Enhancing Proxies

Abstract: SUMMARY Applications that use the reliable Transmission Control Protocol (TCP) have a significant degradation over satellite links. This degradation is mainly a consequence of the congestion control algorithm used by standard TCP, which is not suitable for overcoming the impairments of satellite networks. To alleviate this problem, two TCP Performance Enhancing Proxies (PEPs) can be deployed at the edges of the satellite segment. Then these PEPs can use different mechanisms such as snooping, spoofing and splitting to achieve a better TCP performance. In general, these mechanisms require the manipulation of the Internet Protocol (IP) and TCP headers that generates a problem when deploying the standard IP security (IPsec) protocol. The security services that IPsec offers (encryption and/or authentication) are based on the cryptographic protection of IP datagrams, including the corresponding IP and TCP headers. As a consequence, these cryptographic protections of IPsec conflict with the mechanisms that PEPs use to enhance the TCP performance in the satellite link. In this article, we detail the reasons that cause this conflict, and we propose three different approaches to deploy IPsec in a scenario with TCP PEPs. Our proposals provide different trade-offs between security and TCP performance in some typical scenarios that use satellite networks. Copyright © 2012 John Wiley & Sons, Ltd.

Improving MANET routing with satellite out-of-band signaling

Abstract: Routing in mobile ad hoc networks is a complex task due to the mobility of the nodes and the constraints linked to a wireless multihop network (e.g., limited bandwidth, collisions, and bit errors). These adverse conditions impair not only data traffic but also routing signaling traffic, which feeds route computation. In this contribution, we propose to use satellite communications to help in the distribution of mobile ad hoc network routing signaling. The optimized link-state routing (OLSR) is chosen among several routing protocols to be extended with satellite-based signaling, yielding a version we call OLSR hybrid signaling (OLSR-H). This new scheme is evaluated through simulations and yields improvements of approximately 10% in the data delivery ratio compared with a regular OLSR. This evaluation is conducted using two different network topology models, one being fit for representing forest firefighting operations.