WO1999026358A9 - Architecture de systeme wll/vsat integre - Google Patents

Architecture de systeme wll/vsat integre

Info

Publication number
WO1999026358A9
WO1999026358A9 PCT/US1998/024270 US9824270W WO9926358A9 WO 1999026358 A9 WO1999026358 A9 WO 1999026358A9 US 9824270 W US9824270 W US 9824270W WO 9926358 A9 WO9926358 A9 WO 9926358A9
Authority
WO
WIPO (PCT)
Prior art keywords
subscriber
calls
facsimile
communications system
wll
Prior art date
Application number
PCT/US1998/024270
Other languages
English (en)
Other versions
WO1999026358A1 (fr
Inventor
Dilip S Gokhale
Original Assignee
Comsat Corp
Dilip S Gokhale
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Comsat Corp, Dilip S Gokhale filed Critical Comsat Corp
Publication of WO1999026358A1 publication Critical patent/WO1999026358A1/fr
Publication of WO1999026358A9 publication Critical patent/WO1999026358A9/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/18528—Satellite systems for providing two-way communications service to a network of fixed stations, i.e. fixed satellite service or very small aperture terminal [VSAT] system

Definitions

  • the present invention is directed to a technique for the integration of digital Wireless Local Loop (WLL) and Very Small Aperture Terminal (VSAT) satellite technology that enhances the quality of service offered to end users.
  • WLL Digital Wireless Local Loop
  • VSAT Very Small Aperture Terminal
  • VSAT satellite technology has enabled the cost effective provisioning of long-distance telecommunication services to remote areas around the world.
  • WLL technology is being used in several locations around the world to offer cost effective alternatives to wire-line solutions, especially when the subscribers are dispersed over a large geographic area.
  • Service providers are also combining WLL and VSAT technologies in order to cost effectively provide "local" and "long-distance" telephony services.
  • the integration of the two technologies is accomplished by interconnecting the two systems via the use of a standard signaling protocol such as R2, SS#5, or SS#7.
  • the VSAT appears as a transparent alternative to a terrestrial PSTN trunk as far as the WLL system (which also includes the local exchange function) is concerned.
  • This is generally shown in fig. 6, where calls from a WLL subscriber will be routed from a WLL Base Transciever Station (BTS) 114 through a Transcoder and rate adapter (TRAU) 138 to a WLL switch 116a containing a Switch Controller, WLL Interface, PSTN Interface, Cross-Connect, and Fax/Data Inter- working Unit.
  • BTS Base Transciever Station
  • TSW Transcoder and rate adapter
  • VSAT switch 116b which includes a switch controller, PSTN Interface, VSAT Interface, Cross Connect and Fax/Data Inter- working Unit.
  • TRAU 138b and a VSAT modem into the satellite link.
  • Other functions such as O&M are not shown in the figure for the sake of clarity.
  • This approach has the benefit of allowing the two technologies to be selected independently of each other as long as both of them support the common inter-operable signaling interface.
  • a major disadvantage associated with this approach is the fact that service quality is degraded for the following reasons.
  • both VSAT and WLL systems are based on digital technology, and use low data rate encoding (e.g., 8 Kbit/s) for voice services to make efficient utilization of the bandwidth resources.
  • Tandem vocoders e.g., vocoders 138a and 138b in series, one within the WLL system, the other within the VSAT system
  • typically the low rate compression techniques used by the two vocoders are different which further worsens the voice quality.
  • a low rate vocoder incurs buffering delays associated with voice compression at the transmit end, and with decompression at the receive end. Since the two vocoders (one in the WLL system, the other in the VSAT system) operate independently, each incur these delays and hence contribute to a larger overall delay with respect to the end-to-end voice path.
  • low data rate transport e.g. 8 Kbit/s, 16 Kbit s
  • F-IWF, D-IWF facsimile and data inter-working
  • voice band facsimile and data e.g., V.32
  • the transport of voice band data or facsimile also incurs additional delays and quality degradation given the tandem D- IWF/F-IWF units that are required.
  • WLL Digital Wireless Local Loop
  • VSAT Very Small Aperture Terminal
  • Fig. 1 illustrates an integrated WLL VSAT network architecture in accordance with the present invention
  • Fig. 2 is a functional diagram of the arrangement of the integrated WLL/VSAT switch 16 of Fig. 1;
  • Figs. 3a-3b illustrate the handling of local calls by the integrated WLL/VSAT switch in accordance with the present invention;
  • Figs. 4a-4b illustrate the handling of long distance voice calls by the integrated WLL/VSAT switch in accordance with the present invention
  • Fig. 5 illustrates the handling of long distance fax/data calls by the integrated WLL/VSAT switch in accordance with the present invention.
  • Fig. 6 is a diagram of a conventional arrangement for handling calls from a WLL base stations destined for a subscriber through a satellite link..
  • FIG. 1 depicts an integrated WLL/VSAT network architecture according to the present invention.
  • the primary nodes within the network are the integrated
  • the integrated WLL/VSAT node 10 consists of a WLL Base Transceiver Station (BTS) 14, an integrated WLL/VSAT switch 16, and a satellite VSAT modem subsystem 18. It should be noted that these entities are functional representations only and can be combined in physical implementations.
  • the VS AT/PSTN gateway 12 provides an interface from the satellite network to the terrestrial Public Switched Telephone Network (PSTN) 20 as well as any required echo cancellation equipment. Note that several such gateways 12 may be provided to allow for least cost routing.
  • PSTN Public Switched Telephone Network
  • VSAT networks with different multiple access technologies such as FDMA, TDMA, and CDMA as well as networks that support either "star” or “mesh” topologies.
  • the architecture is applicable to WLL networks that conform to technologies such as GSM & IS 54 (TDMA), and IS-95 (CDMA), as well as proprietary digital networks.
  • TDMA GSM & IS 54
  • CDMA IS-95
  • the only restriction is that the VSAT must use vocoder and fax/data interworking schemes that are identical to those used in the WLL network.
  • FIG. 2 shows a high level depiction of the Integrated WLL/VSAT Switch 16 (IWVS).
  • IWVS Integrated WLL/VSAT Switch 16
  • the major components involved and relevant to this invention are Switch Controller 30, WLL Interface 32, VSAT Interface 34, Cross-Connect 36, Transcoder and rate adapter (TRAU) 38, and Fax/Data Interworking Unit 40.
  • Other functions such as O&M are not shown in the figure for the sake of clarity. It should be noted that the figure provides a functional representation, and it is possible that some of the components may be implemented on separate physical entities.
  • the Switch controller 30 is responsible for the centralized control of all signaling from the WLL and the VSAT, and for the control of the hardware resources (e.g., TRAU, Cross Connect) within the Switch 16.
  • the hardware resources e.g., TRAU, Cross Connect
  • the WLL interface 32 is typically expected to conform to DS-1 or E-l specifications, with system specific signaling and O&M communications with the BTS 14, and signaling communications (e.g., to setup/tear-down calls) with the WLL subscribers.
  • the VSAT interface 34 is also expected to conform to digital DS-1 or E-l specifications, and implement system specific signaling and O&M communications to the Network Control Center, e.g., for call setup/tear-down, and in-band signaling with the remote node, e.g., during the call.
  • the cross connect 36 provides for the interconnection of the time slot resources on the external WLL/VSAT interface as well as to other switch resources such as the TRAU 38 and the F-IWF/D-IWF 40. It should be noted that the cross-connect 36 is required to support sub-rate (e.g., 16 Kbit/s) switching.
  • an implementation could combine the WLL-BTS and/or the VSAT modem function into the WLL/VSAT switch 16.
  • the Switch Controller 30 is responsible for interpreting the signaling exchange with the WLL subscriber 50 (via the BTS) and for determining whether an incoming call is local (i.e., switched to another WLL subscriber at the site) or long distance (either to a PSTN subscriber or to a WLL subscriber at another site). As shown in Figure 3 a, for local calls, the IWVS switches the call through the TRAU function and then back out through the WLL interface to WLL BTS, and thence to the second subscriber.
  • the F-IWF/D-IWF is introduced in the traffic path instead of the transcoder 38. It should be noted that it may also be possible to bypass the TRAU 38 and F-IWF/D-IWF functions for a local call depending upon the WLL system that is being used, as is illustrated in Fig. 3b.
  • Figs. 4a and 4b show the path associated with a "long distance" voice call that is placed by the WLL subscriber in communication with the WLL BTS 14.
  • the IWVS 16 at the subscriber site does not introduce the TRAU function 38 in the traffic path.
  • the remote end where the call is destined to a
  • the TRAU 120 provides for the voice compression/decompression functions. If the remote station is another WLL/VSAT node, then depending upon the WLL technology, the same technique may be applied as described above with reference to Fig. 3b, as is illustrated in Fig. 4b.
  • Figure 5 shows the path associated with a "long distance" voice band facsimile or data call.
  • the F-IWF or D-IWF function along with the rate adapter function within the TRAU 138, is introduced in the traffic path only at the PSTN gateway node 12.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Telephonic Communication Services (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Relay Systems (AREA)

Abstract

L'intégration des technologies WLL et satellites VSAT permet d'améliorer le traitement des communications téléphoniques et de données qui proviennent d'une ligne d'abonné numérique sans fil (WLL) et qui sont destinées à des abonnés locaux ou longue distance. Le système intégré de l'invention utilise des vocodeurs, des adaptateurs de débit (38) et des intégrateurs fax/données (40) identiques dans chacun des systèmes, ainsi que des commandes associées (30) de manière, lors de l'établissement d'un appel, à mettre en/hors circuit ces unités pour assurer un service de meilleure qualité que les services classiques.
PCT/US1998/024270 1997-11-14 1998-11-13 Architecture de systeme wll/vsat integre WO1999026358A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US6604797P 1997-11-14 1997-11-14
US60/066,047 1997-11-14

Publications (2)

Publication Number Publication Date
WO1999026358A1 WO1999026358A1 (fr) 1999-05-27
WO1999026358A9 true WO1999026358A9 (fr) 1999-08-26

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1998/024270 WO1999026358A1 (fr) 1997-11-14 1998-11-13 Architecture de systeme wll/vsat integre

Country Status (1)

Country Link
WO (1) WO1999026358A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002093303A2 (fr) * 2001-05-14 2002-11-21 Spacenet, Inc. Procede et appareil de verification de transactions
FR2863797B1 (fr) * 2003-12-15 2006-02-24 Cit Alcatel Compression/decompression de couche deux pour la transmission mixte synchrone/asynchrone de trames de donnees au sein d'un reseau de communications

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5081703A (en) * 1990-06-27 1992-01-14 Pactel Corporation Satellite mobile communication system for rural service areas
JP2901170B2 (ja) * 1993-05-27 1999-06-07 ケイディディ株式会社 衛星／陸上移動体通信システム統合方式
US5828951A (en) * 1994-08-29 1998-10-27 Nec Corporation Mobile satellite terminal equipment

Also Published As

Publication number Publication date
WO1999026358A1 (fr) 1999-05-27

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