Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/10—Small scale networks; Flat hierarchical networks
  • H04W84/14—WLL [Wireless Local Loop]; RLL [Radio Local Loop]
• • 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
  • H04B7/1853—Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
  • H04B7/18567—Arrangements for providing additional services to the basic mobile satellite telephony service

Definitions

• Transfer control point capable of being used in a device for connecting a telephone switch located in an isolated region to a fixed telephone network
• the invention relates to a device for connecting a first fixed telephone network to a second fixed telephone network via a radiotelephone network comprising one or more satellites, several fixed radiotelephone terminals making it possible to replace a cable link, conventionally called junction when it is to connect two switches.
• Each fixed radiotelephone terminal performs functions similar to those of a conventional portable radiotelephone terminal, but it can be connected, by a local switch of the second fixed telephone network, to any of the fixed terminals of this second fixed telephone network, to the instead of being used by a single user.
• the device according to the invention can be used to connect to a national public telephone network a regional public network serving a city located in an isolated region where the laying of a cable, or other terrestrial infrastructure, would be too costly.
• This regional network comprises at least one switch which serves a group of fixed user terminals, ensuring the routing of calls arriving from the first network.
• Each fixed radiotelephone terminal is used successively for different user terminals, since these are not used permanently.
• Several radiotelephone terminals can share the same frequency band by means of a distribution over time, or a distribution by codes.
• the invention relates more particularly to radiotelephone networks of a type derived from the GSM type, which will comprise a stationary satellite or scrolling satellites.
• GSM or derivative networks have the following characteristics:
• Each geographic area is divided into cells, to allow the reuse of carrier frequencies.
• a gateway manages the resources of each cell, with regard to the carrier frequencies and the channels carried by each carrier frequency.
• At least one switching center in the mobile radio service manages: calls, connections with the fixed telephone network, and databases containing: the MS-ISDN directory number (Mobile station ISDN directory number), l international subscriber identity IMSI (International mobile subscriber Identity), and the location of each mobile subscriber, by means of databases called Visitor location register (VLR) and nominal location register HLR (Home Location Register).
• MS-ISDN directory number Mobile station ISDN directory number
• IMSI International mobile subscriber Identity
• VLR Visitor location register
• HLR Home Location Register
• Classic or derived GSM networks are not designed so that several subscribers use the same user terminal.
• the user personalizes the terminal they use by inserting an identification card called SIM (Subscriber identification module) containing an international IMSI mobile subscriber identity which determines the account on which calls will be billed.
• SIM Subscriber identification module
• this terminal is designated in radio messages by a temporary mobile subscriber identity, called TMSI (Temporary mobile subscriber identity), which makes it possible to protect the anonymity of the user.
• TMSI Temporal mobile subscriber identity
• an authentication procedure uses a secret key contained in the SIM identification card, to prevent a fraudster from using, the IMSI identity or the TMSI identity of another user, when a call is made and when a call is received.
• a first object of the invention is a transfer control point capable of being used in a device making it possible to connect a telephone switch located in an isolated region to a fixed telephone network via junctions supported by a plurality of fixed radiotelephone terminals d 'a radiotelephone network; a plurality of user terminals being connected to this telephone switch; at least one transfer control point coupling the fixed telephone network and a switching center of the mobile service belonging to the radiotelephone network; this mobile service switching center coupling all the junctions supported by these fixed radiotelephone terminals at this control point; this control point comprising: - means for making calls to fixed radiotelephone terminals;
• the transfer control point thus characterized coordinates the radiotelephone terminals by placing a number, designating a fixed radiotelephone terminal, in the "called address" field of the SETUP message sent to a switching center when establishing a connection.
• a transfer control point is characterized in that it further comprises means for transmitting the directory number of a user terminal which is called, to a switching center belonging to the radiotelephone network, by placing this number in the "called sub-address" field of the SETUP message sent when establishing a connection supported by a fixed radiotelephone terminal.
• a transfer control point is characterized in that it further comprises means for retransmitting to a local switch of the fixed telephone network the directory number of a user terminal of the telephone network fixed when this terminal is called by a user terminal which is attached to the switch located in the isolated region, by placing this number in the "called address" field of a SETUP message sent to said local switch when establishing a connection supported by a fixed radiotelephone terminal.
• a second object of the invention is a fixed radiotelephone terminal capable of being used in a device making it possible to connect a telephone switch located in an isolated region to a fixed telephone network via a plurality of fixed radiotelephone terminals of a radiotelephone network.
• a plurality of user terminals being connected to this telephone switch; at least one transfer control point coupling the fixed telephone network and a switching center belonging to the radiotelephone network; this switching center of the mobile service coupling junctions supported by these fixed radiotelephone terminals to this control point; characterized in that it comprises means for extracting from a SETUP message the directory number of a user terminal which is attached to the switch located in the isolated region and which is called; and to send this number to the switch located in an isolated region, in the form of a conventional signaling message.
• the fixed radiotelephone terminal thus characterized allows direct selection on arrival of a call from a terminal of the fixed telephone network, to a terminal connected to the switch located in the isolated region.
• a third object of the invention is a switch in the mobile radiotelephony service, capable of being used in a mobile radiotelephony network comprising fixed radiotelephone terminals connected to a telephone switch to which a plurality of user terminals are connected.
• the switch of the mobile radiotelephone service, thus characterized, allows the direct selection of the called terminal, among all the user terminals which are connected to the switch located in an isolated region, on the arrival of a call from a user terminal belonging to the conventional telephone network.
• a fourth object of the invention is a switch for a mobile radio service, capable of being used in a mobile radio network comprising fixed radio telephone terminals connected to a telephone switch to which a plurality of user terminals is connected.
• the switch of the mobile radiotelephony service, thus characterized, allows the direct selection of a user terminal belonging to the conventional telephone network, upon the arrival of a call coming from a terminal connected to the switch located in the isolated region.
• FIG. 1 represents the block diagram of an exemplary embodiment of the device according to the invention, in an example application.
• FIG. 3 represents a time diagram illustrating the operation of a first variant of the device according to the invention, during the establishment of a communication in this example of application.
• FIG. 1 represents the block diagram of an example of application of the device according to the invention, for providing the services of a telephone network national switch, PSTN, to an IC community located in an isolated area.
• PSTN Public switched telephone network
• PLMN Public land mobile network
• the PLMN network comprises a geostationary satellite or several scrolling satellites, and mainly serves mobile radiotelephone terminals PT.
• a switching center for the mobile radio service, MSC is connected to a satellite S by a gateway GSS which maintains a radio link with the satellite S.
• the switch SW communicates with the satellite S by means of n radiotelephone terminals RTa, RTb, ..., RTn.
• Each fixed radiotelephone terminal RTa, RTb, ..., RTn is connected by a conventional telephone cable to the switch SW, and comprises a device for reading an identification card.
• SIMn conventional cards are inserted into these readers, respectively, and each stores: an international mobile subscriber identity, respectively IMSIa, IMSIb, ..., IMSIn; and a secret key, respectively Ka, Kb, ..., Kn.
• Each fixed radiotelephone terminal RTa, RTb, ..., RTn has a directory number, respectively: MS-ISDNa, MS-ISDNb, ..., MS-ISDNn.
• the PSTN network comprises at least one transfer control point, TCP, allowing access to the satellite S via the GSS gateway, and the switching center MSC of the mobile radio service which serves the terminals RTa, RTb, ..., RTn .
• a user terminal, UTO for example, of the PSTN network is connected to a local switch LE, which can communicate with the transfer control point, TCP. In other examples, it could be connected to the LE switch via a private switch.
• Each fixed radiotelephone terminal RTa, RTb, ..., RTn respectively has a processor Pa, Pb, ..., Pn provided with a program which determines the operation of this terminal.
• the operation is identical to that of a conventional radiotelephone terminal, of the GSM or derivative type, except for the function tion of the called terminal and the direct selection function on arrival, specific to the device according to the invention.
• a preferred embodiment consists in using a conventional radiotelephone terminal, of the GSM or derivative type, by only modifying the program of the processor, in order to perform the functions specific to the device according to the invention.
• Each of the radiotelephone terminals RTa, RTb, ..., RTn can only be in one of the following states:
• a terminal being considered to be available even if it is in the process of localization or authentication.
• a terminal which is in the available state listens to the search messages. It changes state when the PLMN network calls it to establish a communication. Authentication and location procedures are carried out by the terminal in a conventional manner.
• a radiotelephone terminal RTa, RTb, or ..., RTn establishes a communication for a call arriving from the PLMN network or leaving from a terminal UT1, ..., UT100, it is necessary to authenticate this radiotelephone terminal to avoid frauds.
• An authentication procedure is carried out according to a standardized GSM procedure, using a secret key which is contained in the SIM card. The authentication procedure is carried out with a secret key which is specific to the radiotelephone terminal in question, and which is supplied to it by its SIM card.
• a radiotelephone terminal When a radiotelephone terminal receives a message which contains a temporary TMSI identity, instead of an IMSI identity, the processor of this terminal compares this with the temporary TMSI identity which it keeps in memory.
• the processor of this terminal compares this with the temporary TMSI identity which it keeps in memory.
• all user terminals UT1, ..., UT100 are identified by the PSTN network by one hundred directory numbers of the "fixed subscriber" type.
• FIG. 2 illustrates the operation of this exemplary embodiment.
• Each radiotelephone terminal RTa, RTb, ..., RTn makes it possible to establish a junction, respectively Ca, Cb, ..., Cn, each junction being able to carry a telephone channel.
• the TCP transfer control point manages the use of these junctions, as if the MSC center, the GSS gateway and satellite S were transparent. He knows the state and coordinates the use of fixed radiotelephone terminals RTa, ..., RTn. Junctions in use are shown in bold lines in the figure.
• MSC mobile radio service
• the direct selection function upon arrival of a call is carried out according to the following method which does not require modification of the PLMN radiotelephone network, because it is provided for in the GSM standard.
• the PSTN network direction towards the IC community is carried out according to the following method which does not require modification of the PLMN radiotelephone network, because it is provided for in the GSM standard.
• the TCP point sends to the MSC center a SETUP message conforming to the ISDN signaling procedure, by placing, in the "called address" field of this message, the mobile subscriber directory number, MS-ISDNa of the radiotelephone terminal RTa that he chose from the available terminals.
• the MSC center extracts the MS-ISDNa number from the SETUP message sent by the TCP point, then performs a search procedure for the RTa radiotelephone terminal corresponding to the MS-ISDNa number.
• the MSC center prepares a new SETUP message, in accordance with the GSM signaling procedure, by placing, in the "called address” field of this message, the MS-ISDNa number thus extracted; and by placing, in the "called sub-address” field of this message, the directory number ISDN2 of the terminal UT2 called, this number being supplied to it by the local exchange LE.
• the terminal RTa extracts the directory number ISDN2 from the SETUP message, and retransmits it to the switch SW so that the latter can select the user terminal which is called.
• each terminal RTa, RTb, or ..., RTn is modified to extract, from the SETUP message received for the establishment of each call, the directory number of the user terminal UT1, ..., UT100 which is called ; and to send this number to the switch SW, in the form of conventional signaling messages, for example using the analog signaling protocol R2, 10
• the selection method For a call from one of the user terminals UT1, ..., UT100, of the community IC, and intended for a user terminal of the PSTN network, for example the terminal UTO, the selection method is the following :
• the switch SW places an MS-ISDNtcp directory number designating the TCP transfer control point in the "called address" field of a SETUP message, in accordance with the GSM signaling procedure. On the other hand, it places the ISDNO directory number of the called UTO terminal in the "called sub-address" field of this SETUP message.
• the switch SW knows the state of all the fixed radiotelephone terminals RTa, RTb, or ..., RTn to which it is connected. He chooses one from among those available, RTa for example. It sends this SETUP message to the MSC center when establishing a connection supported by this fixed radiotelephone terminal RTa.
• the MSC center extracts the ISDNO directory number from the "called sub-address" field of the SETUP message.
• the MSC center knows the ISDNtcp directory number of the TCP point. It calls the TCP point, by its directory number ISDNtcp.
• the MSC center retransmits, at the TCP point, the ISDNO directory number thus extracted, by placing it in the "called address" field of a new SETUP message conforming to the ISDN signaling procedure.
• the TCP point retransmits the ISDNO directory number to the local LE switch.
• FIG. 3 represents a time diagram illustrating in more detail the operation of a first variant of the device according to the invention, during the establishment of a communication between a user terminal UTO connected to the PSTN network and a terminal of user, for example UT2, of the isolated community IC:
• a user picks up the handset of the UTO terminal and dials the ISDN2 directory number of the UT2 terminal. This number indicates that it is necessary to establish communication via the TCP transfer control point.
• the local switching center LE of the PSTN network, sends a message to the TCP transfer control point requesting the establishment of a communication.
• the LE switch and the TCP point exchange messages to transmit digit by digit, at the TCP point, the directory number ISDN2 designating the terminal called UT2.
• the TCP point knows the state of all the Ca, Cb, ..., Cn junctions. II- chooses an available junction from the Ca, Cb, ..., Cn junctions, for example the Ca junction; and, as part of an example ISDN procedure, it sends a message, called SETUP, in accordance with the ISDN signaling procedure. This message is sent to the switching center MSC of the mobile radio service, asking it to establish a communication.
• the TCP point places in this SETUP message:
• the MSC center consults the GSM network databases to find out the geographic area of the radiotelephone terminal designated by MS-ISDNa, in the same way as for a conventional mobile terminal.
• the HLR recorder indicates to the MSC center that this radiotelephone terminal is located in one of the geographic areas served by the satellite S.
• the MSC center transmits a search message in this area, called PAGING REQUEST of the RTa radiotelephone terminal designated by this identity IMSIa or TMSIa.
• the RTa fixed radiotelephone terminal is available and listens to the search messages, at the instant considered. He receives this message.
• the RTa terminal then sends a response message, called PAGING RESPONSE, to the GSS gateway.
• the GSS gateway responds to it by assigning a radio channel to this RTa terminal. 9) The RTa terminal then sends a message to the switching center
• the GSS gateway, the RTa terminal, and the MSC center exchange messages, to carry out the authentication and encryption procedure, in a conventional manner.
• the MSC center sends the RTa terminal, via the GSS gateway, another message called SETUP, in accordance with the GSM signaling procedure, requesting the establishment of a connection, and containing:
• the terminal RTa extracts from the SETUP message the directory number ISDN2 of the user terminal UT2. It then sends a message to the SW switch to indicate the arrival of a call.
• the terminal RTa then sends a message to the center MSC to confirm that it establishes a communication with the requested user terminal, UT2.
• the switch SW sends to the terminal RTa a message requesting the transmission of the first digit of the directory number of the requested terminal, UT2.
• the RTa terminal sends an alert message to the MSC center, via the GSS gateway, to indicate that a ringing signal is sent to the called terminal, UT2. 1 3
• the terminal RTa sends the first digit of the directory number ISDN2 of the terminal called UT2, to the switch SW. The latter then asks him for the second digit, etc.
• the terminal UT2 sends an acknowledgment to the switch SW.
• a user picks up the handset from the UT2 terminal.
• the latter sends the switch SW a message requesting the establishment of the communication.
• the switch SW sends to the radiotelephone terminal RTa a message requesting the establishment of voice communication, and starting the charging.
• the switch SW signals to the terminal RTa that a user answers the call.
• the terminal RTa requests the switching center MSC to connect the requesting terminal UTO.
• the MSC center forwards this request to the TCP control point.
• the TCP control point sends a message to the local LE switch requesting the establishment of the connection and the start of charging.
• the MSC center sends an acknowledgment to the RTa terminal for the connection establishment request.
• the TCP control point signals to the local LE switch that a user has answered.
• the local exchange LE sends a message to the requesting terminal UTO indicating that the connection is established.
• FIG. 4 represents a time diagram illustrating the operation of a variant of the device according to the invention, during the establishment of a communication between a user terminal UTO connected to the PSTN network and a user terminal UT2 of the isolated community IC: 31) A user picks up the handset of the UTO terminal and dials the ISDN2 directory number of the UT2 terminal. This number tells the switch 14
• the local switching center LE of the PSTN network, sends a message to the TCP transfer control point requesting the establishment of a call. In this message, it places the directory number ISDN2 of the terminal UT2 which is called. The TCP point acknowledges receipt.
• the TCP point knows the state of all the Ca, Cb, ..., Cn junctions. It chooses an available junction from the Ca, Cb, ..., Cn junctions, for example the Ca junction; and sends a message, called SETUP, in accordance with the ISDN signaling procedure. This message is sent to the switching center MSC of the mobile radio service, asking it to establish a communication.
• the TCP point places in this SETUP message the international mobile subscriber identity MS-ISDNa of the radiotelephone terminal RTa which corresponds to the chosen junction, Ca. It is placed in the "called address" field of the SETUP message.
• the MSC center consults the GSM network databases to find out the geographical area where the terminal designated by MS-ISDNa is located, in the same way as for a conventional mobile terminal.
• the HLR recorder tells him that the RTa terminal is located in one of the geographic areas served by the S satellite. Via the GSS gateway and the S satellite, it transmits in this area a message, called PAGING REQUEST, to search for the terminal designated by this IMSIa or TMSIa identity.
• the RTa fixed radiotelephone terminal is available and listens to the search messages, at the instant considered. He receives this message. It compares the IMSIa identity received with the IMSI identity stored in its SIM card. If the message contains a TMSIa identity, the terminal RTa compares the TMSIa identity received with that stored. It is thus able to recognize its IMSIa identity (or possibly TMSIa).
• the RTa terminal then sends a response message, called PAGING RESPONSE, to the GSS gateway.
• the gateway responds by assigning a radio channel to this RTa terminal.
• the terminal RTa then sends a message to the switching center MSC, via the gateway GSS, in response to the search message.
• the GSS gateway, the RTa terminal, and the MSC center exchange messages, to carry out the authentication and encryption procedure.
• the MSC center sends the RTa terminal, via the GSS gateway, another message called SETUP, in accordance with the GSM signaling procedure, requesting the establishment of a connection, and containing the MS-ISDNa number of the RTa radio terminal which corresponds to the Ca junction, in this example, this MS-ISDNa number being placed in the "called address" field of the SETUP message.
• the terminal RTa then sends a message to the switch SW to indicate the arrival of a call.
• the RTa terminal then sends a message to the MSC center to confirm that it accepts the communication.
• the RTa terminal then sends an alert message to the MSC center.
• the MSC center transmits the alert to the TCP point.
• the switch SW sends an acknowledgment message to the terminal RTa, for acknowledgment of the sending of the message 43 indicating the arrival of a call.
• the RTa terminal sends a message to the MSC center, via the GSS gateway, asking it to establish the connection.
• the MSC retransmits this message to the TCP point.
• the latter establishes the connection, and therefore starts the charging process.
• the MSC center sends the RTa terminal a message called CONNECT ACK to indicate that the connection is actually established.
• the switch SW requests the terminal RTa to transmit the first digit of the number of the called terminal. This request is made in the form of a DTMF character (Dual Tone Multi Frequency).
• the terminal RTa requests the MSC center to transmit this first digit in the form of a DTMF character.
• the MSC center requests the LE center to transmit this first digit. 16
• the center MSC sends to the terminal RTa a message called START ACK DTMF for acknowledgment of the transmission of the request 52.
• the RTa terminal sends to the MSC center a STOP DTMF message to request that the sending of the DTMF character be stopped.
• the MSC center sends the RTa terminal a message called STOP
• the LE switch sends the first digit of the ISDN2 directory number of the terminal called UT2, to the MSC center.
• the GSS gateway, the MSC center, and the RTa terminal exchange messages to retransmit the first digit to the RTa terminal, in the form of a DTMF character.
• the terminal RTa sends the first digit to the switch SW. The latter then asks him for the second digit, etc.
• the switch SW sends a ringing signal to the called terminal UT2.
• the terminal UT2 sends an acknowledgment to the switch SW.
• the called user picks up the handset from the UT2 terminal.
• the latter sends the switch SW a message requesting the establishment of the communication.
• the switch SW sends to the terminal RTa a message requesting the establishment of voice communication.
• the GSS gateway, the RTa terminal, and the MSC center exchange messages to indicate the end of the transmission of the directory number ISDN2, and to request the local exchange LE to connect the requesting terminal UTO.
• the MSC center forwards this request to the LE switch via the TCP control point.
• the local exchange LE sends a message to the requesting terminal UTO indicating that the connection is established. 1 7
• the charging therefore begins before the terminal called UT2 has responded, and even if it cannot respond. This taxation can therefore be considered inconvenient in certain cases.
• the scope of the invention is not limited to radiotelephone networks using satellites, which are derived from networks of the GSM type.
• the invention can be applied to conventional GSM type networks.

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

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• 1998
  • 1998-02-16 FR FR9801821A patent/FR2775152B1/fr not_active Expired - Fee Related
• 1999
  • 1999-02-15 CA CA002286565A patent/CA2286565A1/fr not_active Abandoned
  • 1999-02-15 JP JP54114899A patent/JP2001520843A/ja active Pending
  • 1999-02-15 WO PCT/FR1999/000325 patent/WO1999041917A1/fr not_active Ceased
  • 1999-02-15 US US09/402,535 patent/US6434385B1/en not_active Expired - Fee Related
  • 1999-02-15 EP EP99903751A patent/EP0976263A1/de not_active Withdrawn

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