摘要:

AbstractThis 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

ISSN:0737-2884    

DOI:10.1002/sat.4600100503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSatellite 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 disc

ISSN:0737-2884    

DOI:10.1002/sat.4600100504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper presents a conceptual description of a number of possible satellite network architectures for integration into and between the emerging narrowband 64 kb/s based integrated services digital networks (ISDNs). The discussion, which focuses on functional and architectural aspects of network‐integrated satellite systems, is based on two underlying themes. First, the satellite system, as a strict digital transmission system in international ISDN networks, must be virtually ISDN service transparent (i.e. it must not cause any unintended degradation to the transported signals and communication protocols). Secondly, the inherent features of satellite systems are exploited to offer additional functional network support to the ISDN network capabilities for select ISDN service

ISSN:0737-2884    

DOI:10.1002/sat.4600100505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper presents work performed at COMSAT Laboratories to develop a prototype on‐board baseband switch. The switch design is modular to accommodate different service types, and the architecture features a high‐speed optical ring operating at 1 Gb/s to route input (up‐link) channels to output (down‐link) channels. The switch is inherently a packet switch, but can process either circuit‐switched or packet‐switched traffic. If the traffic arrives at the satellite in a circuit‐switched mode, the input processor packetizes it and passes it on to the switch. The main advantage of the packet approach lies in its simplified control structure. Details of the switch architecture and design, and the status of its implementation,

ISSN:0737-2884    

DOI:10.1002/sat.4600100506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe concept of afullymeshed network of very small terminals is presented for personal communications overKu‐band satellite transponders. In this concept, undesirable double‐hop delays are avoided for voice communications between these terminals. The bandwidth and power resources of the transponder are efficiently shared by users in a simple demand‐assigned manner via code‐division multiple access (CDMA).1,2Voice, data and facsimile are statistically multiplexed at each terminal. In order to minamize terminal costs, frequency‐precorrected and level‐preadjusted continuous wave (CW) tones are sent from the central network control station in each beam. The terminals in each down‐link beam can use these pilots as references for antenna acquisition and tracking, as reliable frequency sources, and as indicators of signal fade for up‐link power control (ULPC). The potential CDMA ‘near‐far’ problem due to up‐link fades is mitigated by using ULPC. Quasi‐burst‐mode transmission is employed to minimize the potential loss of clock and pseudorandom number code synchronization. When these terminals are used only to interconnect into the public switched telephony networks (PSTNs) through large, hub‐like gateway stations, they can employ flat‐plate antenna technology. The complete terminal can thereby be packaged into a briefcase so that it is easily

ISSN:0737-2884    

DOI:10.1002/sat.4600100507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper reports on laboratory measurements to determine the characteristics of error bursts encountered on INTELSAT IDR and IBS links for data rates between 64 and 44,736 kb/s. In addition to burst length distributions, several other burst statistics are presented: number of errors per burst, average BER within bursts, and the distribution of error‐free block lengths. These results are intended for use in system design and evaluation of video/speech/data codec performance which are employed on such link

ISSN:0737-2884    

DOI:10.1002/sat.4600100508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper discusses functional and architectural aspects and suitable networks scenarios for the integration of international fixed satellite systems, such as the INTELSAT system, in and between digital networks implementing the new CCITT synchronous digital hierarchy (SDH). The paper presents SDH transmission network functional requirements, and combines them with current and anticipated future FSS operational requirements. It is shown that integration permits the use of SDH functions and features for enhanced network service provisioning by FSS in the international network fabric, and leads to new FSS system design criteria.

ISSN:0737-2884    

DOI:10.1002/sat.4600100509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWideband packet networks operate at rates equal to, or higher than, 64 kb/s, but lower than the basic broadband rate of 150 Mb/s, on cables or satellite links. Wideband packet protocols are the transmission protocols for these networks. They define open interfaces that can be used for public and private ISDNs. The protocols are defined in CCITT Recommendations G.764 and G.765. This paper describes the objectives of the wideband protocols, and how the objectives were achieved.

ISSN:0737-2884    

DOI:10.1002/sat.4600100510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSurface acoustic wave (SAW) filters are key devices in developing the bandwidth‐variable filter matrix for the subchannel switched frequency division multiple access (SS/FDMA) system. This paper addresses the design and fabrication of two 250 MHz SAW filters employing temperature‐stable ST‐cut quartz substrates. The specafications for these filters are decided with due consideration of practical use by INTELSAT‐type satellites. Measured electrical responses of the individual and combined channels show satisfactory performance. Computer simulations are performed using the measured responses to assess the effects of the SAW filters on digital carriers. Finally, the effects of the temperature and ageing stability characteristics are discussed based on the measured and calculated re

ISSN:0737-2884    

DOI:10.1002/sat.4600100511

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper considers a satellite network with data messages being transmitted by land mobile users according to slotted Aloha multiple access. The mobile communication links suffering from multipath fading and signal shadowing are modelled as Gilbert‐Elliott channels. FEC block coding is used to correct transmission errors. The maximum achievable information throughput and the mean packet delay are derived from a combined analysis of the multiple access and FEC/ARQ protocol. The results show that the additional overhead necessary for FEC is outweighed by the benefit in throughput and delay. Finally, the capture effect and its consequences are discusse

ISSN:0737-2884    

DOI:10.1002/sat.4600100512

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY