EP1025679A1 - Systeme de telecommunication - Google Patents

Systeme de telecommunication

Info

Publication number
EP1025679A1
EP1025679A1 EP98949836A EP98949836A EP1025679A1 EP 1025679 A1 EP1025679 A1 EP 1025679A1 EP 98949836 A EP98949836 A EP 98949836A EP 98949836 A EP98949836 A EP 98949836A EP 1025679 A1 EP1025679 A1 EP 1025679A1
Authority
EP
European Patent Office
Prior art keywords
hybrid network
internet
network
packet
hybrid
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP98949836A
Other languages
German (de)
English (en)
Inventor
Martin Daniel Hathanson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Paxgrid Telemetric Systems Inc
Original Assignee
Hathanson Martin Daniel
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 Hathanson Martin Daniel filed Critical Hathanson Martin Daniel
Publication of EP1025679A1 publication Critical patent/EP1025679A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5691—Access to open networks; Ingress point selection, e.g. ISP selection
    • H04L12/5692—Selection among different networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation

Definitions

  • the present invention relates to the field of wireless data communications using satellites and land-mobile radio in the form of terrestrial RF packet networks. More specifically, the invention relates to a system and method of combining satellite and terrestrial RF packet networks into a hybrid network and is embodied in fixed and mobile equipment capable of using this hybrid network.
  • the connection between the gateway and a computer in a fixed-location is typically established using some data link technology such as X.25, Frame Relay, Ethernet and so forth, provided by a public telecommunications carrier, and with which the gateway equipment is compatible.
  • some data link technology such as X.25, Frame Relay, Ethernet and so forth
  • the end-users of RF packet networks are typically charged on a per-packet basis by the operator of the gateway and the wireless data links, it is convenient to refer to the end-users as subscribers, which connect to the RF packet networks through access devices.
  • a fixed subscriber connects to an RF packet network through a plug-in card adapter for the data link to the gateway network whereas a mobile subscriber connects to an RF packet network through a radio modem which implements the airlink protocol of the specific RF network technology. Both the adapters and the radio modems are called network "access devices".
  • A. fixed subscriber consists of a fixed-location computer with an access device in the form of an adapter for the data link to the gateway.
  • a mobile subscriber consists of a mobile computer and an access device in the form of a radio-modem.
  • Satellite-based networks are those which use satellites to provide the RF data link, called an airlink, to the mobile subscriber. This is in contrast to terrestrial networks which use fixed-location RF transceiver base stations to establish the airlink, deployed similarly to those in cellular telephony.
  • IP addresses Internet addresses
  • Each subscriber would become what is known, in the terminology of the Internet, as a multi-homed host.
  • Any Internet node wishing to communicate with a destination which is a multi-homed host, in such a manner as always to use an available, yet least expensive, route,- needs to be aware of all the alternative IP addresses by which the destination can reached. It should also have knowledge of transient conditions along the alternative RF paths because these affect the choice of IP address to use in transmitting data to the destination.
  • the present invention provides a hybrid RF packet network which enables the subscriber to obtain coverage which is unrestricted in terms of geographic boundaries but which makes use of the satellite data links only when it is required. It also enables the subscriber to send or receive Internet datagrams.
  • the system comprises two principal components:
  • a Hybrid Network Radio which constitutes a network access device for mobile subscribers.
  • a Hybrid Network Gateway which constitutes a network access device for fixed- location subscribers.
  • this system treats the combined radio network as a single abstract data link.
  • Both the Hybrid Network Radio and the Hybrid Network Gateway are addressable as Internet nodes which are neighbours attached to this link.
  • both the Hybrid Network Radio and the Hybrid Network Gateway have attachments, called interfaces, to two(2) or more RF packet network technologies.
  • the actual mechanism for transmission across the abstract link between any Hybrid Network Radio/ Hybrid Network Gateway pair is a function of the relative costs of traversing the airlinks. For each airlink, this cost is called impedance, the value of which varies with transient conditions such as commercial terms for (a) transmission rates at different times of the day/week/month, and for (b) the length (in octets) of the data packet being transmitted, as well as the ability of a Hybrid Network Radio to transmit or receive over the airlink.
  • the formula for impedance measurement may be different for any Hybrid Network or Hybrid Network Gateway, its application in terms of the variables used is the same for all datagrams transiting these nodes, regardless of their destination. Both the Hybrid Network Radio and the Hybrid Network Gateway always route traffic through the airlink with the lowest impedance and able to detect changes in the impedance value of each RF packet network.
  • Figures 1(a) illustrates the classical interconnect scenario which is characteristic of the Internet and Figure 1(b) shows a method, inferior to the present invention, for using the Internet-based concept of a "multi-homed host" to create a hybrid network.
  • Figure 2 is a general schematic representation of the Hybrid Network Radio and Hybrid Network Gateway in relation to the combined RF packet networks.
  • FIG. 3 is a detailed schematic representation of the Hybrid Network Radio.
  • FIG. 4 is a detailed schematic representation of the Hybrid Network Gateway in relation to the proprietary gateways for each of the wireless networks and to the rest of the Internet
  • FIG. 5 is a schematic representation of the routing mechanism which constitutes the essential innovative characteristic of the present invention.
  • Figure 6 is a schematic representation of the behavior of either the Hybrid Network Radio or the Hybrid Network Gateway when a report is received from an RF packet network that a previously transmitted packet has failed to reach its destination, or that a prior attempt to transmit a packet has failed.
  • Airlink Status Reporting is a schematic representation of the behavior of the Hybrid Network Radio when a report is received from the radio modem that RF contact with the packet network infrastructure has either been lost or re-established.
  • Figure 1(a) is a schematic representation of the classical interconnect concept as it is applied in the architecture of the internet. This is shown in contradistinction to the nature of, and the solution for, the problem of hybrid networking.
  • the internet solves the problem of data packets traversing two or more heterogeneous data links between source and destination computing devices, whereas hybrid networking deals with the choice of only one of several alternative RF paths to traverse along a route between the source and destination.
  • Figure 1(b) illustrates the "multi-homed host” approach to solving the latter problem as an example of a solution which would be inferior to the present invention for the reasons outlined in Prior Art.
  • FIG. 2 shows the two (2) principal components of the present invention in relation to the RF packet networks that they combine.
  • Hybrid Network Radio 20 is attached to a terrestrial RF packet network 60 and to a satellite network 65.
  • Each of the RF packet networks have proprietary gateways to which Hybrid Network Gateway 80 is connected.
  • RF packet network 60 and its proprietary gateway 70 comprise a telecommunications service as does RF packet network 65 with proprietary gateway 75.
  • RF packet network 65 and its proprietary gateway 70 comprise a telecommunications service as does RF packet network 65 with proprietary gateway 75.
  • both services may be provided by two different telecommunications carriers who can remain unaware that Hybrid Network Gateways and Hybrid Network Radios are effectively creating a combined network.
  • the combined network 105 is treated as a single abstract data link technology.
  • Any subscriber connected to this data link can have a unique Internet address. More specifically, each of the interfaces to this data link from both Hybrid Network Radio 20 and Hybrid Network Gateway 80 has only one Internet address.
  • a Hybrid Network Radio in accordance with the present invention is shown in Figure 3.
  • the hardware embodiment 20 of the Hybrid Network Radio contains reusable software module 30 at the core of which is Internet Protocol module 35, called an IP module.
  • IP modules are present in all computing devices which have an address on the Internet.
  • IP modules having only one interface to a specific data link technology are called hosts.
  • the Hybrid Network Radio complies with the aforementioned definition of a router.
  • PPP Point-to-Point Protocol
  • the specifications for the PPP may be found in Simpson, W., Editor, "The Point-to-Point Protocol (PPP)", STD 50, RFC 1661, Daydreamer, July 1994, the contents of which are incorporated herein by reference.
  • the Hybrid Network Radio has an array of interfaces to RF packet networks (data link technologies).
  • these interfaces are for:
  • a terrestrial RF packet network labeled 45(a).
  • IP addresses In a conventional Internet architecture, all these interfaces would have Internet addresses, called IP addresses. However, in terms of the conventional routing task of the IP module, these are all combined into a single abstract data link.
  • a Hybrid Network Gateway in accordance with the present invention is shown in Figure 4, relative to the proprietary gateways for each of the wireless networks and to the rest of the Internet.
  • the Re-usable Software Module 30 of the Hybrid Network Radio is, as the name implies, re-used in Hybrid Network Gateway 80 and therefore all of its components, including the RF path switch, are identical in functionality.
  • the Hybrid Network Gateway interfaces to a fixed subscriber 100 through a generic EP interface 90.
  • 90 is any interface to a network which can be assigned an Internet address and therefore enables the Hybrid Network Gateway to route between the Hybrid Network and the Internet.
  • the fixed subscriber 100 is an Internet node.
  • Hybrid Network Radio has the same behavior as an EP module in any conventional router. It routes traffic between the PPP interface and the abstract data link which combines the RF packet networks However once traffic has been routed to the abstract data link, a choice must be made between an array of alternative RF paths. Module 40, which is not part of a conventional EP module, determines this choice, and is called an RF path switch.
  • the functionality of the RF path switch should be explained in contrast to the conventional Internet routing mechanism, which is as follows.
  • the basic data unit in the Internet is called a datagram.
  • the routing decision taken by the IP module is a function of the destination address encapsulated in the header of the datagram.
  • a router will mask out the host portion of the destination address in order to extract only the network portion. If the router incorporates an interface to that network, then the datagram can be delivered directly to its destination. Otherwise, it examines its routing table to find a route associated with the target address and, if there is a route, it delivers the datagram to the network interface associated with that route. In other words, it passes the datagram along to the next hop indicated by the route.
  • Hybrid Network Radio to determine the RF packet network interface to which the datagram should be delivered shows that this is purely a function of the relative costs of sending the datagram, (encapsulated in a data link layer frame) along any one of the wireless data link paths.
  • RF path switch 40 chooses the path of least impedance. Therefore if the impedance l of RF packet network 60 is less than impedance I2 along RF packet network 65, RF path switch 40 chooses 60 as the medium through which to transfer the datagram.
  • the entries in its routing table can be dynamically changed as topological conditions in the Internet change. As routers are added or removed, or traffic congestion problems are reported, the routers which detect these phenomena can propagate the information throughout the Internet via a set of protocols in which only routers participate. As new information is received, the router may change some of its route entries .
  • Most RF packet technologies include a mechanism for reporting of transmission errors to the users which initially requested the transmission.
  • the cause of errors can vary from failures of the airlink to a temporary condition of insufficient holding buffers in a modem driving the transmitter.
  • the network interfaces 45(a), (b) and (c) from Figure 3 propagate these errors to the EP module 35 by indicating a unique identifier for the datagram as well as a unique code which represents the nature of the error.
  • Figure 6 shows the behavior of a network interface and the EP router on reception of an error report.
  • Input 1 from a network access device to an RF packet network interface 45 represents an error report which is assumed to encapsulate both the cause of the error and an identifier for the transmitted packet which failed to cross the airlink.
  • the network access device is shown to be a radio modem 50 (a), (b) or (c), as in the case of a hybrid Network Radio, but it could also be an adapter 85, as used in a Hybrid Network Gateway).
  • the RF packet network interface propagates this report to the IP module 40, which, in turn, produces two (2) outputs.
  • Output 3 is an instruction to generate, and queue for transmission, an ICMP (Internet Control and Message Protocol) error message destined for the source of the datagram which failed to be transmitted.
  • ICMP Internet Control and Message Protocol
  • ICMP is the method used within the Internet for nodes to communicate "out-of-band"; i.e. to report problems and to implement diagnostic request-response protocols such as the well-known "ping".
  • the specifications for ICMP may be found in Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, USC/lnformation Sciences Institute, September 1981, the contents of which are incorporated herein by reference.
  • the ICMP message type used in Output 3 is commonly called
  • the specific cause of the failure is derived from the error report received from the interface 45, and is recorded in the CODE field of the ICMP message.
  • Output 4 is an instruction to modify, in accordance with the nature of the error, the impedance value of the RF path for the entry in the routing table which corresponds to the original destination of the datagram.
  • the source of the datagram either mobile subscriber 10 or a fixed subscriber (see Figure 7)
  • receives the ICMP DESTINATION UNREACHABLE message it may choose to resend the datagram. Therefore, the choice of path for the re-transmitted datagram will take into account the new impedance value of the first RF path.
  • the formula for calculating the impedance of an RF packet network may vary with the technology and the commercial terms offered for the service. For instance, if commercial rates vary with the number of octets in a packet and with the time of day, impedance measures should take these factors into account. When an error report is translated into DESTINATION UNREACHABLE, the impedance on this RF path is set to a value which cannot be exceeded on any other path, so that the RF path switch will avoid this path until conditions change.
  • Some RF packet network technologies provide a mechanism for a mobile network access device, i.e. a radio modem, to generate reports regarding the status of the airlink, or the ability of the device to transmit on the airlink. With respect to the functionality of the present invention, the most important of these reports are the establishment and loss of RF contact with the packet network.
  • Figure 7 illustrates this mechanism in terms of how these reports are used by the Hybrid Network Radio to modify the routing table entries.
  • Input 1 is a status report from the modem 50(a) that RF contact with the network infrastructure has been lost.
  • the RF packet network interface 45(a) propagates this report to the IP module (Output 2), which activates timer 36 in order to wait a suitable delay t before raising the impedance of RF path 60 to its maximum possible value (Outputs 4,5). Subsequently, the RF path switch will avoid sending datagrams along RF path 60 because its impedance will be as great as or greater than all other RF paths for packet networks to which the IP module is attached.
  • the impedance for the RF path 60 is reset to its original value when a status report is received from the radio modem 50(a) indicating that RF contact with the network infrastructure has been re-established.
  • Output 7 is an instruction to reset the impedance measure for RF path 60 in the routing table.
  • Output 8 is an instruction to generate and transmit across the airlink a control packet indicating that the mobile subscriber is within RF contact.
  • a control packet is defined as a packet which does not carry a payload for a higher-level protocol such as an EP datagram.
  • the packet header includes a field which is used to specify a type, wherein control packet types can be distinguished from other packets carrying payloads for higher-level protocols. If an RF packet network does not define such a field, then it must be defined, at the beginning of the user data area of each packet, in such a manner as to enable the transmitting and receiving network interfaces to recognize it.
  • the packet header also includes an identification of the sender in the form of an address which is "native" to the RF packet network. This is commonly called a "hardware address" and is mapped within the receiver's routing tables to an EP address.
  • the control packet resulting from Output 8 in Figure 7 is called an RF_P ATH JPD ATE packet. It informs the receiver that the sender has entered the coverage area of the RF packet network. The receiver can therefore change, if required, the impedance value for the RF path to the sender.
  • the timer 36 in Figure 7, activated when loss of RF contact is reported, is used to avoid unnecessary transmission in the case where there are spurious oscillations between loss and re-establishment of RF contact. In other words, if contact is lost, the timer may still be canceled if, before the interval has elapsed, a status report is received indicating re-establishment of contact. In such a case, the RF_P ATHJJPD ATE control would not be generated and transmitted. Interval t can be calibrated to each RF packet network technology.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Relay Systems (AREA)

Abstract

La présente invention concerne un système permettant de combiner des réseaux HF à commutation par paquets séparés et incompatibles en un réseau HF à commutation par paquets hybride offrant les services les moins onéreux possibles avec une couverture de territoire illimitée. Ce système comprend deux (2) composants principaux à savoir (i) une radio de réseau hybrique (20) permettant à un abonné mobile (10) d'avoir accès au réseau hybride(105), et (ii) une passerelle de réseau hybride (80) permettant à un abonné fixe (100) d'avoir accès au réseau hybride. Ces deux composants comprennent des modules qui leur permettent de (a) s'interfacer avec le réseau hybride sous forme d'une simple liaison de données abstraites avec une seule adresse Internet; (b) d'avoir accès à Internet et d'avoir d'autres accès à partir d'Internet pour les abonnés reliés à ces modules, et (c) sélectionner de manière intelligente la trajectoire HF optimale sur laquelle envoyer des paquets par le réseau hybride, en fonction des conditions d'impédance à changement dynamique dans les réseaux de paquets HF individuels.
EP98949836A 1997-10-23 1998-10-23 Systeme de telecommunication Withdrawn EP1025679A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US6321897P 1997-10-23 1997-10-23
US63218P 1997-10-23
PCT/CA1998/000986 WO1999022497A1 (fr) 1997-10-23 1998-10-23 Systeme de telecommunication

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EP1025679A1 true EP1025679A1 (fr) 2000-08-09

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Application Number Title Priority Date Filing Date
EP98949836A Withdrawn EP1025679A1 (fr) 1997-10-23 1998-10-23 Systeme de telecommunication

Country Status (5)

Country Link
EP (1) EP1025679A1 (fr)
JP (1) JP2001522169A (fr)
AU (1) AU9616998A (fr)
CA (1) CA2307218C (fr)
WO (1) WO1999022497A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100030423A1 (en) 1999-06-17 2010-02-04 Paxgrid Telemetric Systems, Inc. Automotive telemetry protocol
US20020150050A1 (en) 1999-06-17 2002-10-17 Nathanson Martin D. Automotive telemetry protocol
US7228072B2 (en) * 2001-10-16 2007-06-05 Telefonaktiebolaget Lm Ericsson (Publ) System and method for integrating a fiber optic fixed access network and a fiber optic radio access network
CA3058076A1 (fr) 2016-07-01 2018-01-04 Paxgrid Cdn Inc. Systeme d'authentification et d'autorisation d'acces a un environnement vehiculaire a acces sans fil par des dispositifs clients et de comptabilisation de la consommation a cet ef fet

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
US4999833A (en) * 1985-05-06 1991-03-12 Itt Corporation Network connectivity control by artificial intelligence
US5073900A (en) * 1990-03-19 1991-12-17 Mallinckrodt Albert J Integrated cellular communications system
EP0615391A1 (fr) * 1993-03-09 1994-09-14 ALCATEL BELL Naamloze Vennootschap Réseau de communication mobile
WO1995025407A1 (fr) * 1994-03-17 1995-09-21 Sierra Wireless, Inc. Modem pour transmission a commutation en mode paquet et circuit
US6477581B1 (en) * 1996-04-09 2002-11-05 International Business Machines Corporation Location/motion sensitive computer connection

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Title
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Also Published As

Publication number Publication date
CA2307218A1 (fr) 1999-05-06
CA2307218C (fr) 2008-09-30
JP2001522169A (ja) 2001-11-13
AU9616998A (en) 1999-05-17
WO1999022497A1 (fr) 1999-05-06

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