非再生式星上处理和程控交换及其支持IP业务的可能性

星上处理技术对提高卫星通信的传输质量和频谱利用率起着关键性的作用,已经成为卫星通信领域研究的热点。再生式星上处理虽然优点显著,但其技术难度大、设备复杂度高及应用灵活性小,系统容量也受到设备复杂度的限制。针对再生式星上处理的一些不足,本文通过将连续波时分复用技术和程控电路交换相结合,提出一种非再生式星上处理和交换技术,并论证了其支持IP业务的可能性。得出结论:基于连续波时分复用和程控电路交换相结合的中继设备能够实现强实时性IP业务的一跳传输,在一定程度上提高了卫星通信系统的通信容量,降低了卫星设备复杂度。      

Services and supporting architecture of the ESA OBP system

The ESA on-board processing (OBP) satellite system using on-board regeneration and baseband circuit switching has been designed to provide ISDN connectivity and services to users on a Pan-European basis. It is thus seen at its periphery as a 2 Mb/s primary rate access, hence allowing for the interconnection of equipment and terminals compatible with this standard interface. Among the various possible network architectures that the system could support, the business-oriented closed networks look most promising. It has therefore been retained as a prime design driver for OBP system developments. Optionally, connectivity can be offered in an optimized manner to pure data networks, e.g. for LAN-to-LAN interconnection at rates up to 1 Mb/s. In the paper, communication services and networking capabilities offered by the system are briefly reviewed. The internal characteristics of the satellite system allowing for such capabilities are then reviewed and the corresponding performance outlined. The system is shown to be compatible with critical CCITT performance criteria.     

Saw chirp filter technology for satellite on-board processing applications

Market growth in the area of thin route satellite communications services has led to consideration of non-traditional system architectures requiring sophisticated on-board processing functions. Surface acoustic wave (SAW) technology exists today which can provide implementation of key on-board processing subsystems by using multicarrier demodulators. This paper presents a review of this signal processing technology, along with a brief review of dispersive SAW device technology as applied to the implementation of multicarrier demodulators for on-board signal processing.     

The role of satellite communication in the ISDN era

Satellite communications can play an important role in provisioning the next-generation telecommunications services and networks, provided that the protocols specifying these services and networks are satellite-compatible. After a brief discussion of narrowband circuit and packet mode integrated service digital network (ISDN) services, the paper focuses on emerging standards in frame relay, broadband ISDN (BISDN) and universal personal telecommunications (UPT). The specific parameters and procedures of frame relay and BISDN protocols which are affected by a satellite delay are identified, and congestion and resource management functions for frame relay and BISDN are discussed in detail. Specific ground functions and possible on-board functions are identified as potential candidates for implementation via neural network technology. Finally, the implication of UPT standards on satellite networks is discussed.     

Advanced RF switching and on-board regeneration technologies for digital satellite communications

In this paper, functional blocks of a generic on-board processing payload are identified, and some key technology implementation issues for on-board RF and/or baseband switching, signal regeneration and processing are addressed. The design and performance characteristics of a microwave switch matrix and a 120 Mb/s coherent quadrature phase shift keying demodulator for satellite applications are presented. This hardware is realized with monolithic microwave integration technology. Significant performance improvement and reduction in size and weight, as well as enhanced subsystem reliability, have been demonstrated, making these technologies attractive for flexible communications satellite payload architectures of the future. Transmission analysis is performed to quantify link budget advantages that could be obtained by using on-board regeneration.     

Switching for IP-based multimedia satellite communications

This paper discusses the structure and performance of an Internet protocol (IP)-based satellite communications system to provide multimedia services. Uplink scheduling and switching to support IP differentiated services (DiffServ) traffic in a multibeam environment are addressed. End-to-end performance of a multibeam satellite communications system using an on-board switch is evaluated using simulation. Aggregate real-time and non-real-time traffic using different DiffServ classes is considered and the effects of their burstiness and long-range dependent behavior on the queueing performance are examined. Multiple-frequency time-division multiple-access is used on the uplink in conjunction with a dynamic capacity allocation scheme. Higher priority is given to voice and video real-time traffic to avoid delay variation. On-board downlink queue for non-real-time traffic is provided to achieve high statistical multiplexing gain.     

VSAT networking concepts and new applications development

The authors present some innovative very small aperture terminal (VSAT) technology that can be used to support new applications. The first of these applications explores the possibility of realizing a VSAT-based satellite wide area network (SWAN) to provide flexible interconnection between local area networks (LANs) and metropolitan area networks (MANs) as well as gateway access to centralized information databases and computing services. A second application deals with the potential provision of ISDN-compatible services via VSATs in conjunction with existing satellites as well as future advanced satellites (ADSATs) having onboard switching and processing capabilities. The use of VSATs to solve backhaul interconnection/internetworking problems associated with evolving mobile satellite (MSAT) communication networks is discussed     

On-board processing for anti-jam packet data satcom services

Future military satellites may take advantage of developments in space components to provide on-board processing within the communications payload. They will also need to support military packet communications networks. The author presents some of the criteria which will affect the performance of a satellite supporting an antijam packet data service. The architecture of the communication protocols is discussed and results presented from simulation of the system     

The Challenge of 21st Century Satellite Communications: INTELSAT Enters the Second Millenium

This paper addresses the issues concerning the future of satellite communication, which will be influenced by the advancement of fiber optical cables, the proliferation ofC- andKu-band satellites, the standardization of ISDN, the requirements for new and low cost services, the economic disparity among countries, the extent of institutional policy changes, as well as technological breakthroughs. The factors will dictate and shape, both internationally and domestically, the directions of future satellite communications. In addition, the following subjects are discussed:bulletservice and traffic projectionsbulletaccess strategiesbulletmodulation alternativesbulletsatellite switching and on-board processingbulletphase array antennasbulletlow-altitude orbit optionsbulletsatellite lifetime extension.     

Satellite communications systems move into the twenty‐first century

This paper discusses the evolution of communication satellite systems and communications satellite technology from the 1960's to the 1990's. The paper identifies the key attributes of satellite communications that has driven this evolution and now drives the future directions such systems will take. The paper then discusses the future direction of communication satellite systems including DBS, MSS, FSS and hybrid satellite/terrestrial systems. The paper points to the continued evolution of the satellite payload to use of spot beams, onboard processing and switching, and intersatellite links, with capability for higher EIRPs. The paper also identifies the earth station trends to more compact, lower cost stations, produced in higher volumes, with the handheld phone for MSS operation being the prime example of this trend. The paper then points to some revolutionary trends in satellite communication networks being proposed for MSS and FSS applications involving fleets of NGSO satellites combined with more extensive ground networks involving new networking concepts, new services (such as multimedia) and new hybrid configurations working with terrestrial networks, involving a host of new network issues and operations. This revised version was published online in June 2006 with corrections to the Cover Date.     

Comparative study of switching methods for the on-board processor in a mobile satellite communications system

An on-board processor makes efficient use of the channel capacities in a satellite communications system employing multibeam technology, and an on-board processor has been developed for the Engineering Test Satellite VIII (ETS-VIII), which is the experimental satellite for a multibeam mobile satellite communications system. The multicarrier time division multiple access (MC-TDMA) system used in this communications system, however, sometimes causes internal congestion in the on-board processor. This paper describes the results of computer simulation studies of the traffic capacity obtained using three baseband switching methods and also describes the results of studies of the on-board processor design for each of the methods. The computer simulation results indicate that the probability of internal congestion due to the TDMA system is very small when the simultaneous-slot switching method is used, and the design study results reveal that an on-board processor using the simultaneous-slot switching method will be compact and lightweight and will consume little power. © 1998 John Wiley & Sons, Ltd.     

The Future of Satellite Communications in Europe

Europe has so far launched four experimental and six operational communications satellites successfully. Fifteen more spacecraft are scheduled to be launched before the end of 1990. As everywhere in the world, requirements for new telecommunications services are emerging very rapidly, and it is becoming increasingly apparent that the planned developments in terrestrial networks (ISDN, radio cellular networks) will fail to meet all the needs adequately, either in scope or in time scale. Against this background, it is shown that satellites of conventional design, carrying transparent payloads, are well suited to satisfying many of the new requirements in the short term. For the longer term, i.e., from the year 2000 onwards, innovative system concepts are being developed in which the satellite is called upon to perform more sophisticated functions requiring very advanced antennas, on-board processing, and intersatellite links.     

卫星通信的技术发展及应用

简要回顾了卫星通信的发展历程，介绍了一些正在发展的技术，并对卫星通信在未来中的主要应用进行了阐述。卫星通信的重要技术发展包括基于数字视频广播（DVB）的标准的建立、星载开关（On-Board Switching）的应用。其他的技术包括多协议标记交换（MPLS）在卫星网络上的应用及卫星间和平台间光学连接的应用。     

A future satellite communications system using millimetre-wave bands and an on-board processor

This paper proposes the system concept of a personal satellite communications system that will be available in the first decade of the 21st century. Technologies of millimetre-wave bands and an onboard processor with baseband switching promise to meet the requirements of a personal communications system: portability, low-cost, and large capacity. Based on the prospects of these technologies, the most likely parameters for the future personal satellite communications system and the configuration of a suitable on-board processor are proposed. A trial model of such an on-board processor has been made. In this paper, details of the trial model on-board processor and its future developments are described.     

Satellite Scenarios and Technology for the 1990's

Commercial satellite communications continues to undergo changes arising not only from advancing technology but also from new service offerings and regulatory activities. As the communications industry grows more competitive, future directions in satellite communications will become more economically than technologically motivated. This paper addresses the future of satellite communications, emphasizing fixed satellite services but also covering maritime mobile and broadcast satellite services. Following a brief recapping of the past, current services are discussed and future services are projected for the above service categories. A projection is made of the economics of satellite communications systems using gateway and varying degrees of distribution of earth stations, for both INTELSAT VI and future multibeam satellites and the TAT-8 fiber-optic undersea cable. After a brief allusion to systems design considerations, the anticipated technology projections towards the year 2000 for satellite communication services (including satellite antennas, transmitters and receivers, and on-board interconnection subsystems) are presented in some detail. Finally, it is concluded that satellite communications will have a major role in this epoch, and widespread use of low-cost customer premise earth station may justify more sophisticated and more expensive spacecraft.     

Critical issues of onboard switching in DVB-S/RCS broadband satellite networks

The next generation of broadband satellite networks is challenged to accommodate multimedia services while concurrently integrating with terrestrial IP networks. With IP applications dominating the Internet, carrying IP traffic over the satellite has been under intensive study. Originally developed to bring digital television home through satellites, the DVB-S and DVB-RCS standards empower interactive satellite communications with economical standardized satellite terminals. Furthermore, onboard switching technology is increasingly gaining attention, due to optimized bandwidth usage, fully meshed network topology through one satellite hop, and quality of service guarantee. This article investigates the onboard switching technologies in DVB-S/DVB-RCS broadband satellite networks. Aside from the network system infrastructure and switch hardware architecture, the QoS mechanisms supported by the switch onboard the satellite are discussed in depth.     

On-board switching and processing

Findings from NASA's space electronics division's (SED's) advanced systems studies related to future communications satellite services that will require onboard switching and processing technology are reviewed. SED's digital signal switching and processing technology program is reviewed. This program responds to specific systems technology development needs for enabling commercial development of future satellite services. The technologies include: modulators, demodulators, and forward error-correction hardware for space- and ground-based applications; onboard information switching and processing, onboard network control, and health monitoring; and cost-efficient ground terminals. The in-house systems integration, test, and evaluation (SITE) project, which includes a laboratory testbed for evaluating technology in a simulated systems environment, is reviewed     

System concept for a digital repeater intended for a future generation of german telecommunication satellites

The derivation of a system concept for the digital multi-service repeater starts from evaluating the mission profile and the antenna concept elaborated so far. Furthermore, the repeater concept is shaped by Ka-band propagation conditions, the kind of integration of a down-link TV-distribution service into the prevailing multi-beam communications mode and readily available digital technologies. It is intended to embark on a completely regenerative approach using a unified switching concept for all services accompanied by a large amount of rearrangement functions in the foreground. An attempt is made to define those network control functions and procedures to be located on-board exploiting the fact that the repeater already acts as a central switching node. The discussion of on-board digital technologies concentrates upon a multicarrier demodulator concept and a candidate solution for the baseband switch. One general boundary condition is pronounced due to uncertainties about the actual traffic scenario in the future: all repeater resources must be accessible for the most important of the services considered, i.e. the provision of satellite business services.     

The use of satellite technology for oceanic air traffic control

The authors discuss the use of satellite technology for communications, navigation, and surveillance within the context of providing air traffic services and control to aircraft operating in US oceanic airspace. Particular emphasis is placed on automatic dependent surveillance, a technique that uses satellite communications channels to relay position data generated by an aircraft's on-board navigation system. Using these same channels, reliable, timely, and direct pilot/controller communications can be provided within the oceanic environment     

High-Speed Packet Switching Systems for Multimedia Communications

High-speed packet switching (HPS) systems can Provide flexible, economical, high-quaiity services for integrated voice, video, and data communications. To realize such HPS systems, methods have been developed to bring about high-speed protocol processing as well as a system architecture for facilitating high-throughput switching. Adopting the parallel processing algorithm into protocol processing allows us to achieve high-speed packet protocol processing of about 100 times faster than conventional processing. Furthermore, a fully distributed system architecture in addition to hierarchical interconnection networks can achieve high-capacity packet switching systems. The proposed HPS system is thus capable of accommodating lines of up to 10-50 Mbits/s, of providing high-throughput switching capability of 1 000 000 packets/s, and of having an average delay of less than 2 ms. Furthermore, an evaluation of network delay performances of video conferencing and voice communications indicate that HPS systems are quite suitable for handling such multimedia communications.