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Digital Satellite Communications, 1995., Tenth International Conference on

Date 15-19 May 1995

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  • Design considerations for compressed digital TV satellite systems

    Publication Year: 1995 , Page(s): 261 - 268 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    A confluence of technological advances portends exciting new possibilities for video telecommunications services available from geosynchronous satellites. Satellite payload technology is offering high power shaped coverages at Ku-Band. Small earth station technology has reached the point where low system noise temperatures are economically feasible and nearly routine, and perhaps the key ingredient has been the remarkable progress in the area of digital video encoding-wherein both standardized (i.e., open system MPEG) and proprietary implementations are allowing perfectly satisfactory video at data rates that only a few years ago barely yielded acceptable video-conferencing quality. Allied and associated with the progress in video source encoding, practical low-cost approaches to very efficient digital modulation formats, including FEC, have become available. Given the pace of advances in each of these areas, even further progress seems assured View full abstract»

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  • Application of the access network concept of ETSI to the on-board processing system of the European Space Agency (ESA)

    Publication Year: 1995 , Page(s): 167 - 171 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    This paper describes the application, to the onboard processing (OBP) system of the European Space Agency (ESA), of the access network (AN) concept and related protocols which have been standardised by the European Telecommunication Standardisation Institute (ETSI). The advantages of this approach as well as mandatory modifications to the ETSI protocols are listed. The mission of the OBP system is to offer ISDN (integrated services digital network) services to the European continent via a geostationary satellite. These standard services, providing connections via primary rate access (PRA) and basic rate access (BRA), are complemented with services for which satellites have a long tradition, i.e. multi- and broad-cast services but at multiples of 64 kbit/s View full abstract»

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  • An experience on implementing TMN interfaces for an OBP satellite network

    Publication Year: 1995 , Page(s): 180 - 186 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The management of a satellite network and its components is usually achieved using proprietary access methods between the management application and the managed resources. This fact makes difficult to integrate the satellite network management with the management of other resources, or even to integrate different network management applications of the satellite network. This paper describes an experience on implementing a standardized network management architecture for the management of an on board processing satellite network which will link hundreds of small user ground stations across Europe in an ISDN environment. The architecture is based on the telecommunication management network (TMN) architecture, defined by ITU-T. The main characteristics of TMN are the definition of a standardized interface (Q3) for the operation systems, and several entities (mediation devices and Q-adapters) to reach heterogeneous network resources from these operation systems. This experience is based on the definition, design and a prototype implementation of a mediation device, to allow the standardized management of an on board processing network. This entity, defined in the TMN architecture, acts as a management gateway (proxy) between the proprietary access method of the satellite network and a standardized network management protocol. The paper concludes with some lessons learned in this experience about the adequacy of the current architectures and technology of network management for its application to the satellite networks View full abstract»

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  • Implementation of ATM via satellite for B-ISDN

    Publication Year: 1995 , Page(s): 137 - 142 vol.1
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    Advances in digital signal processing and telecommunication technologies has led to the development of ATM and B-ISDN. Satellite communications systems can play an important role in the development of the initial experimental systems and also in the fully developed networks due to their features of flexible wide coverage, independent of ground distances and geographical constraints, multiple access and multipoint broadcast. This paper presents an implementation structure of ATM via satellite and its capabilities of supporting B-ISDN based on a demonstration system developed within the RACE CATALYST project View full abstract»

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  • A hybrid CDMA scheme and demodulator structure for KA band operation

    Publication Year: 1995 , Page(s): 17 - 23 vol.1
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    This work derived from a study of the impact of 20/30 GHz operation on the OBP requirements for a satellite system intended to serve private user networks of small fixed terminals. As the cost of the HPA was a dominant factor we examined continuous transmission schemes and concluded that CDMA was potentially attractive as with synchronous CDMA mutual interference can be zero. Therefore no sacrifice in bandwidth occupancy is needed and the `demultiplexer' complexity is comparable to that for FDMA consisting of a FFT type processor involving only additions. A hybrid approach which reduces the peak processing requirement is the MF-CDMA scheme in which each 2 Mb/s carrier is shared using CDMA with different spreading factors but a common chip rate. This scheme is simple in demultiplexing, allows variable rate transmissions and avoids the synchronisation problems in a pure CDMA scheme View full abstract»

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  • On the utilization of packet reservation multiple access (PRMA) technique in satellite systems

    Publication Year: 1995 , Page(s): 277 - 281 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    Packet reservation multiple access (PRMA) is being developed in the framework of the RACE A-TDMA study as one of the two candidate access techniques, together with code division multiple access (CDMA), for third generation mobile systems. The paper deals with the topic of applying PRMA techniques to satellite systems View full abstract»

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  • Archimedes-CD-audio and data broadcast services to mobile subscriber

    Publication Year: 1995 , Page(s): 382 - 389 vol.2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    This paper presents a business concept for the provision of new high rate, high quality broadcast services mainly to mobile but equally well to fixed consumers by applying the newly developed DAB standard. All necessary elements to implement and operate such a system in the three main economic regions of the world make it a very attractive international system. Due to the state-of-the-art technology it could commence offering innovative services from the very first day of the 21st century. The system configuration is based on a study for the European Space Agency. The main objective of the system investigation was to identify a technically and commercially viable system concept. Each spot of the system represents an independent resource on its own. The capacity of a single DAB-multiplex transmitted in this spot comprises programmes and data services which are of special interest in the particular service areas View full abstract»

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  • A modified Viterbi decoder based upon cross correlation for use in bandwidth efficient systems

    Publication Year: 1995 , Page(s): 1 - 8 vol.1
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    A novel convolutional decoding technique is described which improves error performance of synchronous data links operating in a high radio interference environment. The decoder has as its basis the Viterbi algorithm but decoding decisions are based upon maximum correlation rather than maximum log likelihood ratio. The radio interference originates from data transmitted on overlapping QPSK carriers. First the theoretical aspects of the carriers orthogonality were investigated. It was found that the raised cosine shaping of the data symbols removed the orthogonality which had been established between the carriers carrying symbols of rectangular shape. The theoretical aspects of the decoding process were examined resulting in a precise definition of the technique together with clarification as to how reduction in transmission errors can be achieved. The most relevant parameter for the analysis of this decoder is defined as a decoding variable associated with each state of the conventional decoder. This variable describes the contents of the radio interference and has 12 distinct values for two overlapping QPSK signals. The performance of the decoding process is compared with that obtained from 8 levels of quantized soft decoding using the Viterbi algorithm. Computer simulations are presented that show that when both types of decoder are operating in extreme radio interference conditions such as in CDMA systems, the new decoder BER performance is superior to that of the conventional Viterbi decoder. But when the decoding signal is corrupted by Gaussian noise only then both decoders exhibit exactly the same BER View full abstract»

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  • Advanced communications technology satellite (ACTS) applications and experiments

    Publication Year: 1995 , Page(s): 159 - 166 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    The ACTS satellite was designed to provide demand assigned multiple access (DAMA) digital communications with a minimum switchable circuit bandwidth of 64 kbps, and a maximum channel bandwidth of 900 MHz. It can, therefore, provide service to thin routes as well as connect fiber backbones in supercomputer networks, across oceans, or to restore full communications in the event of national or manmade disasters. Service can also be provided to terrestrial and airborne mobile users. The ACTS satellite has met its design requirements and its architecture has been verified by the experiments completed so far. ACTS has paved the way for the use of hopping spot beams, the use of demand assigned on-board switching, the use of Ka band, and the introduction of high bandwidth channels. These features will result in lower cost and wider availability, especially in isolated areas View full abstract»

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  • Adaptive multiple access protocols for VSATs providing voice/data services and ATM interconnection

    Publication Year: 1995 , Page(s): 351 - 357 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    We discuss an adaptive multiaccess scheme that, when applied to a VSAT satellite network, could efficiently accommodate traffic consisting of short, interactive data messages, longer file transfers and voice calls. This enables a large number of users to share the satellite channel. The difficulties associated with the introduction of speech are discussed and ways to deal with these are suggested, so that VSAT systems become able to provide a wide range of multimedia services to geographically dispersed users. We conclude our discussion by turning our attention to the need for VSATs to become compatible with the emerging ATM technology and thus provide a way of remote connection of thin route users to the B-ISDN View full abstract»

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  • International compressed video by satellite

    Publication Year: 1995 , Page(s): 250 - 260 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    NTL has been at the forefront of the development of MPEG digital video compression, launching its MPEG 1 System 2000 product in early 1993. This was the first commercial implementation of the MPEG standard for use in broadcast television applications and many organisations have since operated the system both for point to multipoint distribution to cable head-ends and also for point-to-point delivery of television services. September 1994 saw the launch at the International Broadcasting Convention of NTLs system 3000 MPEG 2 system with a demonstration of eight television programmes carried in a 33 MHz RF channel, each programme being encoded at bit rates of between 3 and 4 Mb/S. NTL is an established service provider and operates a major earth station located at its main office site near Winchester in Southern England. The earth station offers C and Ku-band international services for video, voice and data as well as direct-to-home uplinking. Since January 1994, NTL has been operating international compressed video links over satellite. This paper describes in technical detail the planning criteria adopted for implementing the transmissions and includes the results both of test transmissions and customer contracted services View full abstract»

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  • Improvement and application of the INTELSAT (SS)TDMA system

    Publication Year: 1995 , Page(s): 413 - 418 vol.2
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    This paper presents the rationale for improvement of the present INTELSAT (SS)TDMA system, and describes the current INTELSAT program to achieve this goal. The role of TDMA in the INTELSAT system and the performance record and customer benefits are described. Two objectives of this program are to make low cost TDMA terminal equipment available to INTELSAT TDMA system customers, and to enhance the traffic carrying flexibility of the system View full abstract»

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  • Link enhancement for ATM over satellite links

    Publication Year: 1995 , Page(s): 129 - 136 vol.1
    Cited by:  Papers (1)  |  Patents (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    The burst errors experienced on coded satellite links impact the operation of both asynchronous transfer mode (ATM) and ATM adaptation layer (AAL) protocols and their transport in synchronous digital hierarchy/plesiochronous digital hierarchy (SDH/PDH) frames. COMSAT has developed an ATM link enhancer (ALE), which provides significant improvement in the probability of cell discard due to header errors, improves loss of frame performance when using the physical layer convergence protocol (PLCP) in PDH, and reduces certain errors experienced in AAL type 1 and AAL type 3/4. This paper describes the DS-3 hardware implementation of the ALE, including the techniques used to establish and maintain the PLCP and deinterleaver frame synchronization, perform selective interleaving/deinterleaving of ATM cells, and perform header error correction on deinterleaved cells. In addition, it provides a functional description of the ALE and the prototype ALE hardware implementation. The paper summarizes the measured ALE performance in a satellite field trial, and compares its measured and predicted performance using data collected via the field trial View full abstract»

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  • Fault tolerant on-board switches for ATM

    Publication Year: 1995 , Page(s): 88 - 95 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    Reliability of any on-board ATM switch depends on providing redundant paths within the switch. This paper reports on simulated fault injection in a multistage ATM switch based on the augmented shuffle exchange network. Results indicate that an acceptable fault tolerance and performance can be achieved with reasonable buffer sizes at each switching node View full abstract»

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  • Proceedings ICDSC-10. 10th International Conference on Digital Satellite Communications (Conf. Publ. No.403)

    Publication Year: 1995
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (44 KB)  

    The following topics were dealt with VSAT; on-board processing; mobile satellite systems; ATM/SDH; Ka-band use; video compression; intersatellite links; modulation and coding; audio and data broadcasting; TDMA; user experience; thin route/DAMA; operational aspects; multimedia View full abstract»

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  • An overview of mobile satellite systems and their evolution towards satellite personal communication networks

    Publication Year: 1995 , Page(s): 435 - 441 vol.2
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    The paper reviews the evolutionary trend from mobile to personal satellite communications. In addition to summarizing technical/market parameters of present-day (GEO) Mobile Satellite Systems (MSS) and MSSs under development (INMARSAT Network, ESA PRODAT and MSBN, OmniTRACS/EutelTRACS, American and Asia-Pacific Systems,....), an attempt is made to identify critical system/service aspects related to the deployment of personal satellite communications. Such aspects substantially deal with equipment standardization and type approval, frequency spectrum allocation and assignment (i.e. licensing), mutual recognition of licences, multiple-entry provision and so forth. The present situation of “little”, “big” and “super” LEOs is depicted, identifying issues to be addressed when designing and implementing satellite personal communication networks (S-PCN). Inmarsat plans to deploy the “Standard-P” system are also indicated View full abstract»

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  • Access protocols and on-board switch techniques for multimedia personal satellite communications

    Publication Year: 1995 , Page(s): 63 - 71 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The authors draw on four years of study on a proposed Canadian satellite system, to compare switching, uplink access and downlink distribution techniques for multimedia. Satellite systems offer special challenges to those who wish to offer multimedia service at an affordable cost. The space resource is a precious commodity and both bandwidth and power must be used efficiently. The traffic profiles and resource requirements of multimedia sessions are far different than those for telephony. These profiles are examined against conventional link access and switching techniques being used today, in satellite systems, for both single media voice and data. Finally, an optimum combination of uplink access, downlink resource allocation and switching is proposed for a multimedia satellite system. This is compared with more conventional telephony based systems and under a representative multimedia traffic profile, a parametric assessment of satellite resource efficiency is produced View full abstract»

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  • Measurements and modelling of wireless channel for satellite mobile/personal communication systems

    Publication Year: 1995 , Page(s): 106 - 114 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    Propagation channel plays an important role in the overall design of any mobile communication system, even more so for a satellite-based mobile system. Signal propagation mechanisms such as shadowing of the line-of-sight (LOS) signal and multipath reception are the most significant issues of concern to systems designers. Estimation of additional link margin, necessary for low gain low directivity mobile terminal, to provide reasonable service availability is usually a first step towards understanding the propagation impairments. Satellite-mobile link quality to a great extent is determined by the propagation channel characteristics. The propagation channel characteristics are believed to be most significantly dependent upon the mobile surrounding environment. Signal amplitude variations of the order of several dBs may be experienced mainly due to the obstruction of the line-of-sight (LOS) path between a satellite and a mobile over a relatively short duration of time. This effect is known as shadowing. In general, a mobile terminal is not capable of discriminating between the LOS signal and its various reflected replicas. This causes degradation in the received signal due to multipath. For broadband systems, the differential delays of different incoming replicas cause further problems and therefore distort the signal. The paper discusses various aspects of a mobile satellite propagation channel. It outlines CSER activities in modelling the narrowband characteristics, and wideband measurements, of the channel View full abstract»

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  • Self interference in non geostationary satellite systems

    Publication Year: 1995 , Page(s): 290 - 297 vol.1
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    By early 2000, several non geostationary satellite mobile communication systems will be in operation. The frequency bands allocated by the ITU-R to the Mobile Satellite Service (MSS) being scarce, such systems will be allowed to operate only in narrow frequency bands, not large enough to allow them, in the absence of frequency reuse, to cope with the traffic generated by the total number customers. Therefore, the implementation of frequency reuse will be mandatory. The implementation strategy will have to consider reducing as much as possible the system self-noise generated by the interference between spot beams reusing a common frequency band. The important parameter is the ratio C/I between the useful received carrier power on a mobile-to-satellite or satellite-to-mobile link and the overall contribution at the receiver input of interference power generated by other links. This ratio depends on the system characteristics, such as type of orbits, number of satellites in the constellation, antenna radiation patterns, etc. The paper presents a method for calculating the ratio C/I, and the results obtained for two types of constellations. One is a 48 Low Earth Orbit (LEO) constellation, the other is a 12 Intermediate Circular Orbit (ICO) constellation. The results are displayed in the form of maps with C/I areas about the geographical location of a mobile within which a given value of C/I is guaranteed for a given percentage of time for the uplink or the downlink. These results are of paramount importance for designing subsequently a frequency reuse policy View full abstract»

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  • 20/30 GHz satellite communications: the technology is mature

    Publication Year: 1995 , Page(s): 152 - 158 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    The paper addresses from a “strategic” point of view the inherent advantages of Ka-band satellite services as compared to C- and Ku-band systems. The analysis starts from considering Intelsat-like service requirements for four categories of applications (presently rendered at C/Ku bands): (i) trunk telephony; (ii) high capacity data services (cable restoration); (iii) VSAT and (iv) videoconference. Migration of these services to 20/30 GHz is discussed assuming system parameters derived by ITALSAT (Italian domestic satellite programme) experience, and extrapolating equipment costs for both space and ground segments. Results show a fairly promising cost perspective in favour of Ka architectures. Some lessons learned from the 20-year experience we have gained on Ka-band systems makes it possible to outline some design guidelines that can be useful in developing Ka-band satellite systems of the year 2000 View full abstract»

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  • Digital television exciter and receiver for satellite news gathering: digital satellite link performance

    Publication Year: 1995 , Page(s): 244 - 249 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The move toward digital transmission of television signals presents new opportunities and advantages to broadcasters when compared with today's analog links. This is particularly evident in the transmission of television signals by satellite, where the application of digital technology will have a positive impact through greater utilization of transponder resources, lower operating costs, and improved link performance. A new digital television exciter and studio-grade receiver built specifically for the satellite news gathering (SNG) environment have been developed and are discussed in the paper View full abstract»

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  • CADENZA: the World's first ATM switch in the sky

    Publication Year: 1995 , Page(s): 121 - 128 vol.1
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    The system described makes possible the immediate deployment of a satellite-based ATM switch, offering full cell-by-cell connectivity for private networks or for complementing the terrestrial IBCN. By using a conventional transparent satellite, the system avoids the costs, risks and delays associated with new payload development; and with so little equipment in orbit to fail, and none to be superseded, it is inherently reliable and future safe. Nor is it committed to, or dependent upon, any particular satellite or satellite family. On the ground side, the standard interfaces and conventional configuration allow the reuse of standard hardware and software; this not only avoids the costs and risks of unilateral development, but also allows the exploitation of long term maintenance and evolutionary support provided with such products View full abstract»

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  • Design of an integrated protocol architecture for Micro-VSAT networks

    Publication Year: 1995 , Page(s): 358 - 365 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    This paper proposes a voice-data integrated digital network designed for Micro-VSAT networks. The design is the result of a study performed under contract for the European Space Agency, in the framework of the development of a portable VSAT network based on the advanced access technique Bandlimited Quasi-Synchronous CDMA, operating in Ku-band (referred to as CKN in this paper). The study was intended to complete the specifications of the system, and to provide the basis for the development of a simulator, which was used for further system analysis and optimization. The study aimed to define first the services to be supported, and from them define the network in terms of bearer services, specify the mapping of bearer services to the carriers supported by the CKN, and define the protocol architecture and signalling that supports the teleservices over the bearer services. The first generation of the system will implement only a subset of the functions and services considered here. There are a number of issues which are innovative, namely: integration of voice and data applications; integration of circuit and packet switching; integration of connection oriented and connectionless services; out-of-band data during a voice communication; multicast services in both voice and data applications; possibility of sharing communication resources among several virtual networks; direct communication between VSAT terminals, without hub relaying; and transparent interconnection to terrestrial data and voice networks View full abstract»

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  • Timing distribution in an on board processing communication system

    Publication Year: 1995 , Page(s): 79 - 87 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    This paper describes a timing distribution and a synchronisation scheme for a communication system with data regeneration and switching on board the satellite. The proposed concept is applied to a bit-synchronous system where the reference clock is generated on-board from an incoming very stable ground source. An auxiliary ground reference is operating in pre-aligned hot stand by mode, allowing an immediate hand over in case of interruption of the link to the primary reference. Clock quality in terms of phase jitter is evaluated throughout the system and is shown to impose negligible penalty on system performance. The synchronisation scheme has been simulated and successfully demonstrated by means of a laboratory model. The concept described in this paper is applied in the ESA on board processing system currently under development, but as such can be applied to any satellite system with on board regeneration and/or switching View full abstract»

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  • Mobile satellite communication systems. A competitive scenario for new systems and services

    Publication Year: 1995 , Page(s): 450 - 456 vol.2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    A variety of mobile satellite communication systems is available for commercial use while others are going to be introduced on the market in the near future. All that in a competitive communication scenario in which mobile systems based on ground and global S-PCNs (satellite personal communication networks) are becoming more and more aggressive with several systems announced and some of them being implemented. The authors focus on existing mobile satellite systems and their peculiarities, in terms of coverage and connectivity with terrestrial networks and of expected performance. Services already offered by these systems are also outlined. The question is how these systems can be competitive and will survive in the future and which improvements they will need in order to keep the edge for particular niche market. Rather than giving a mere comparison of technical performance of these systems, they present the achievements of the large scale demonstration currently in progress in Europe with the PRODAT system, developed by the European Space Agency (ESA). On the basis of the user reaction noticed during the demonstration, they focus on the winning factors and on a perspective to get mobile satellite systems attractive beyond the end of this century View full abstract»

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