ISSN:0737-2884    

DOI:10.1002/sat.4600120102

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

年代:1994

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600120103

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe integration between cellular networks and satellite systems is a very promising issue, since it permits the immediate provision of the radio services offered by the cellular networks to areas lacking in terrestrial facilities.In this paper the viability of a full integration between the GSM cellular network and a satellite system is dealt with. TheL‐band land mobile payload has been assumed as a reference; nevertheless the presented results can be extended to other payloads.The basic requirement of full integration is that the insertion of the satellite system does not entail any modification of the already existing GSM network.The integration analysis has been carried out by examining both the link feasibility and the network architecture.As far as link feasibility is concerned, the analysis is performed by means of anad hocsimulation tool developed at CSELT (Turin). The simulation results are displayed for GSM speech channels at both full‐rate (TCH/FS) and half‐rate (TCH/HS). Such results are used in order to compute the satellite link budgets and the satellite system capacity. The characteristics of the satellite propagation channel, of the satellite‐compatible mobile station and of the reference payload are explained as well.As far as the network architecture is concerned, the paper identifies the most promising satellite system configuration and the satellite system counterpart of the GSM functional areas (cell, location area, MSC area). Moreover, the problems and the relevant solutions related to the extension of the main GSM procedures (e.g. call set‐up, cell selection/reselection, handover) to the integrated network are dealt with.This paper is based upon the work performed by the authors in the framework of the European Space Agency (ESA) study: ‘Assessment of a public mobile satellite system compatible with the GSM cellular network’, Telespazio (Rome) is the prime contractor of this study.The opinions herewith reported are not necessarily

ISSN:0737-2884    

DOI:10.1002/sat.4600120104

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper deals with an efficient dynamic channel allocation (DCA) technique suitable for applications in mobile satellite cellular networks. A cost function is defined to allow an optimum selection of channels to be allocated on demand. A mobility model suitable for low earth orbit (LEO) satellite systems is presented. The performance of the novel DCA technique in terms of call blocking probability has been derived by simulations. The obtained results are compared with those achieved by a fixed channel allocation (FCA) technique to show a better behaviour.

ISSN:0737-2884    

DOI:10.1002/sat.4600120105

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe paper expands on some specific aspects of personal communications via satellite, often–although not necessarily–envisaging extensive use of ‘small’ satellites, using orbits not necessarily coinciding with the geostationary one (36,000 km), but rather at 1000–11,000 km altitude. One key point to be borne in mind is the issue of internetworking between satellite and terrestrial systems. Network integration should be carefully implemented in order to comply with ITU future public land mobile telecommunication systems (FPLMTS) requirements, also accepted in the European Telecommunication Standards Institute (ETSI) universal mobile telecommunication systems (UMTS). In addition to some insight into the technology of small satellites and associated orbits, architectures and networking aspects of most relevant systems providing personal communication services (PCS) are addressed in some detail, and potential applications highlighted. Frequency spectrum allocation is addressed in the light of the 1992 World Administrative Radio Conference (WARC‐92), taking into account also multiple access problems and regulatory issues such as Federal Communications Commission (FCC) licensing and spectrum sharing debates. Some remarks on critical technologies and cost conclud

ISSN:0737-2884    

DOI:10.1002/sat.4600120106

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

年代:1994

数据来源: WILEY

摘要:

AbstractThere is a very large demand for basic telephone service in developing nations, and remote parts of industrialized nations, which cannot be met by conventional wireline and cellular systems. This is the world' largest unserved market. We describe a system which uses recent advances in active phased arrays, fast‐packet switching technology, adaptive routeing, and light spacecraft technology, in part based on the work of the Jet Propulsion Laboratory and on recently‐declassified work done on the Strategic Defense Initiative, to make it possible to address this market with a global telephone network based on a large low‐Earth‐orbit constellation of identical satellites. A telephone utility can use such a network to provide the same modern basic and enhanced telephone services offered by telephone utilities in the urban centres of fully‐industrialized nations. Economies of scale permit capital and operating costs per subscriber low enough to provide a service to all subscribers, regardless of location, at prices comparable to the same services in urban areas of industrialized nations, while generating operating profits great enough to attract the capital needed for its construction. The bandwidth needed to support the capacity needed to gain these economies of scale requires that the system useKa‐band frequencies. This choice of frequencies places unusual constraints on the network design, and in particular forces the use of a large number of satellites. Global demand for basic and enhanced telephone service is great enough to support at least three networks of the size described herein. The volume of advanced components, and services such as launch services, required to construct and replace these networks is sufficient to propel certain industries to market leadership positions in the early 2

ISSN:0737-2884    

DOI:10.1002/sat.4600120107

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

年代:1994

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600120108

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis article presents an overview of the concept of a multiple purpose global satellite network. It identifies some of the main needs of telecommunication services today, and projects the potential of future demands. It also describes the great possibilities of economic expansion and mass participation in the growth and prosperity of a nation, if basic telecommunication services are accessible on a global scale. The study suggests that the rapid recovery of capital investments on universal satellite networks lies in developing regions through cost‐effective service diversificatio

ISSN:0737-2884    

DOI:10.1002/sat.4600120109

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

年代:1994

数据来源: WILEY

摘要:

AbstractAlthough there is no doubt about the feasibility of personal communications via small satellites in low earth orbit, there is considerable uncertainty about the size of the market, whether the specific applications will be business or personal in context, about the market relationship between voice services and data services, and the implications for system design of any information that might be developed on these questions.This paper will develop the concept that the key to understanding low orbit small satellite communications systems is the message delivery time requirement of markets and that the data services market has a widely varying range of acceptable data delivery times. We estimate the distribution of data delivery time versus population of users on a global basis.A second concept to be developed in this paper is that low orbit satellites are in some respects matched to global data delivery applications because of the daylight time zones and natural delays they impose.Using the estimated market size versus message delivery time, we show that there is a significant design implication for the space segment in terms of the number of satellites, the orbit period, and the use of crosslinks. It will be further shown that the difference in complexity of data and voice services with respect to cost argues for the rapid emergence and success of data services.Finally, we will show that a preferred terminal architecture may be an accessory orappliquefor a personal computer, rather than a small dedicated satellite terminal, based on the extant population of personal computers. A review of the planned terminal architectures of emerging systems reveals that using a personal computer as the basis for a terminal has not yet received wide interest. In particular, the new laptop smaller computers may be the natural catalyst for personal satellite data services in facilitating the terminal.

ISSN:0737-2884    

DOI:10.1002/sat.4600120110

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

年代:1994

数据来源: WILEY

摘要:

AbstractCurrently 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 until the final operation of such networks. This paper deals with basic design problems of LEO/ICO‐based networks. In the first part, estimates for the necessary number of satellites, orbits and number of communication channels per satellite are derived. Since the latter is a crucial quantity, the number of communication links and channels per link are derived with a more elaborate model in the second part of the paper. 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 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 Motor

ISSN:0737-2884    

DOI:10.1002/sat.4600120111

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

年代:1994

数据来源: WILEY