Satellite Multicast Research Articles

Optimization of Dynamic Beam Placement for LEO Satellite Multicast Communications

Optimization of Dynamic Beam Placement for LEO Satellite Multicast Communications

Satellite multi-beam multicast support for an efficient community-based CDN

The design and implementation of an efficient end-to-end IP-based infrastructure for the delivery of multimedia content is of paramount importance in current public networks, dominated by the constant growth of video streaming traffic. Content Delivery Networks (CDNs) represent the main technological solution to manage the huge volumes of traffic involved, by guaranteeing high quality levels to applications and low impact to the core networks, thanks to the efficient distribution of content among edge caches that are located as close as possible to end-users. Nonetheless, the hierarchical data distribution associated with CDNs can be in principle subject to inefficiencies, as well as performance limitations in case of congested segments along the end-to-end delivery path. In this context, we propose the exploitation of satellite multicast capabilities offered by modern high throughput satellite (HTS) platforms, in a virtualized-compatible model, to compensate for flaws of terrestrial networks. The role of satellite communication is to offer multicast support (as a complement to landline connectivity) with wide geographical service areas based on the available satellite beams, enabling a popularity-based content distribution support. In addition, multi-beam satellite technology allows for a more fine-grained approach to popularity evaluation based on user location. The proposed service and the related network configuration are described in the paper, in relation with current and future SatCom platforms. We then present the results of the proposed CDN caching algorithms in a simulated environment, showing promising results associated with a preliminary performance evaluation.

Guest Editorial: IJSCN Special Issue on ASMS2008

This Special Issue of the Wiley International Journal of Satellite Communications and Networking hosts aselection of papers from the fourth Advanced Satellite Mobile Systems (ASMS) Conference, held inBologna, Italy, on 26–28 August 2008. The conference was organized through a joint effort of theUniversity of Bologna, the Institute of Communications and Navigation of DLR (German AerospaceCenter) and the ISI (Integral SatCom Initiative) European Technology Platform, in cooperation with theSatellite Communications Network of Excellence (SatNEx) and the sISI Specific Support Action,supported by the European Commission FP6 and FP7 programmes, respectively.The ASMS conference has become a recognized event for industry and research institutions to exchangeup-to-date information about recent advances and emerging technologies in the field of mobile satellitecommunication systems. In addition, following the successful path opened by the 2006 edition, the scope ofthe conference has been widened to include broadband and broadcast satellite systems. This is veryimportant not only because the major part of the satcom market belongs to broadcasting and broadbandaccess operators but also fundamentally because the convergence of broadcast, mobile and fixed satellitecommunications is essential to offer seamless connectivity anywhere at anytime, which is recognized as thekey element for the successful deployment of future satellite systems.This Issue collects the extendedversions of eight of the best papers presented at the ASMS 2008 Conference. The papers have been selectedwith the aim of providing an insight in the developments and findings in this exciting field. The first papershows that Low Density Parity Check (LDPC) codes can tightly approach the performance of idealmaximum distance separable codes over memoryless erasure channels, under Maximum Likelihood (ML)decoding [1]. The decoding complexity of ML decoding can be kept low thanks to a class of decodingalgorithms which exploit the sparseness of the parity-check matrix to reduce the complexity of Gaussianelimination. The second paper includes a review and characterization of possible data link technologies foraeronautical communications covering a vast range of terrestrial (direct air-to-ground) and satellite-basedsolutions, with the final goal to identify suitable candidates for a future integrated aeronautical networkbased on IPv6 protocol, supporting both cockpit and cabin communications [2]. A new method to enableIPsec authentication and integrity services at the network layer is proposed in the thirdpaper [3]. Target scenarios include satellite multicast for large-scale delivery of data and video content.In these scenarios, a cross-layer architecture can mitigate the effects of physical layer impairments andlarge latency. Stemming from the three-state land mobile satellite channel model used for physical layersimulation in the course of the DVB-SH standardization process, an improved model is proposed in thefourth paper [4]. The new model includes two major modifications: a reduction in the number of states and

A cross‐layer framework for IPsec over satellite links

AbstractThe traditional modular OSI‐layered architecture has served a major role in the development of a variety of protocols. However, as physical layer impairments become complex and time varying, a dynamic cross‐layer design can enable better performance. A Cross‐Layer Architecture (CLA) is proposed to improve performance of error‐tolerant applications running over UDP‐Lite. This approach to implementation introduces new challenges in protocol design, as well as in the area of security, where the study proposes a new method to enable IP security (IPsec) authentication and integrity services at the network layer. Target scenarios include satellite multicast for large‐scale delivery of data and video content. In this scenario, CLA can mitigate the effects of physical layer impairments and high latency. Numerical analysis has shown that a link design employing header compression and cross‐layer signalling may protect protocol headers and can reduce the probability of packet discard. To evaluate the feasibility of the CLA, these methods have been implemented as an extension to the IPsec protocol, named Cross‐Layer IPsec (CL‐IPsec). A satellite emulation platform was used to validate the implementation of CL‐IPsec and to evaluate the overall performance improvement resulting from the proposed CLA. Copyright © 2010 John Wiley & Sons, Ltd.

A feedback suppression algorithm for reliable satellite multicast based on spatial–temporal prediction of the satellite channel

AbstractThe major problem limiting the scalability of large‐scale multicast satellite networks is feedback implosion that arises whenever a large number of users simultaneously transmit feedback messages (FBMs) through the network, thus occupying a significant portion of satellite system resources. In satellite networks operating above 10 GHz, attenuation due to rain constitutes the dominant fading mechanism deteriorating the quality of service. In this paper, a novel scheme for providing large‐scale reliable multicast services through a star‐based geostationary satellite topology is presented incorporating accurate channel modeling of the propagation phenomena. The new protocol is based on the selection of an area representative that provides quick FBMs aiming at suppressing FBMs originating from the rest of the network users. The scheme provides a timely reaction to changes of either the channel conditions or the network topology by properly updating the selection of representatives. Through appropriate simulations, comparisons and examples it is demonstrated that the new approach suppresses FBMs very effectively. Copyright © 2009 John Wiley & Sons, Ltd.

Improving Satellite Multicast Security Scalability by Reducing Rekeying Requirements

As multicasting technologies grow in popularity, so does the need for scalable security architectures to support the user base. Significant research efforts are ongoing in the areas of group-key distribution and management. However, little research has addressed the security of very large, distributed groups communicating via low-earth orbit satellite networks. In this article, we review the requirements common to most secure, multicast networking environments; discuss existing scalable multicast security architectures; and present a novel modular scalable architecture for secure multicast, adapted to a low-earth orbit satellite system. Simulated results reveal a twelve-fold reduction in average user rekeying and an order of magnitude reduction in required key distribution versus the baseline architecture.

Multicast-aware power allocation in multiple spot-beam satellite communication systems

In this paper, we address the problem of user heterogeneity in satellite multicast from the perspective of resource allocation in a multiple spot-beam satellite system that supports both unicast and multicast flows. Satellite communication systems, with their wide-area coverage and direct access to large number of users, clearly have an inherent advantage in supporting multicast applications. In order to remain competitive against other broadband technologies, however, next generation satellite systems will be required to support both unicast and multicast flows and offer optimal sharing of system resources between these flows. We show that user heterogeneity across spot-beam queues may result in lower allocated session rates for active flows, and be perceived as unsatisfactory by potential users when both unicast and multicast flows are active in the system. We propose an optimization-based approach that allocates resources with the goal of smoothing user heterogeneity, and show that resulting session rates are higher on the average for both unicast and multicast flows. This is achieved through the re-distribution of system power among spot-beam queues, by taking into account the load on the queues and the channel states. We conclude that it is possible to increase the average session rates of multicast flows by 25–100%, and the rates of unicast flows by 15–40% compared to the pre-optimization levels. Copyright © 2006 John Wiley & Sons, Ltd.

Transport protocols in multicast via satellite

AbstractIn a wide variety of broadband applications, there is a need to distribute information to a potentially large number of receiver sites that are widely dispersed from each other. Communication satellites are a natural technology option and are extremely well suited for carrying such services because of the inherent broadcast capability of the satellite channel. Despite the potential of satellite multicast, there exists little support for multicast services over satellite networks. Although several multicast protocols have been proposed for use over the Internet, they are not optimized for satellite networks. One of the key multicast components that is affected when satellite networks are involved in the communication is the transport layer. In this paper, we attempt to provide an overview of the design space and the ways in which the network deployment and application requirements affect the solution space for transport layer schemes in a satellite environment. We also highlight some of the issues that are critical in the development of next generation satellite multicast services. Copyright © 2004 John Wiley & Sons, Ltd.

Efficient Support of IP Multicast in the Next Generation of GEO Satellites

Satellites are expected to have an important role in providing the Internet protocol (IP) multicast service to complementing next-generation terrestrial networks. In this paper, we focus on the deployment of IP multicast over the next generation of digital video broadcasting-based geosynchronous earth orbit satellites supporting multiple spot beams and on-board switching technologies. We propose a new encapsulation scheme optimized for IP multicast, which has two distinct modes enabling two alternative on-board switching approaches: the self-switching and the label-switching. We also detail a set of mechanisms and protocols for ground stations, as well as for the on-board processor to allow an efficient multicast forwarding in this type of environment, while reducing the load of control and data messages in the satellite segment, and building efficient multicast delivery trees reaching only the spot beams containing at least one member of the corresponding multicast session. To integrate satellite links in the terrestrial Internet, we present satellite multicast adaptation protocol (SMAP), a protocol which is implemented in satellite stations to process incoming protocol independent multicast-sparse mode (PIM-SM) messages sent by terrestrial nodes to the satellite system. SMAP helps to update the tables required for the mapping between IP packets and MPEG-2 data segments, their switching on board the satellite, and their filtering at the satellite receivers.