Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/02—Terminal devices
  • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
  • H04W76/15—Setup of multiple wireless link connections

Definitions

• Class B terminals ie which can support the CS and PS services consecutively but not simultaneously
• C ie which can support the PS services only
• Class A terminals supporting the simultaneous implementation of CS and PS communications, remain too complex to be easily achievable. In particular, such terminals would require two independent receivers, which would considerably increase their cost.
• DTM functionality (“Dual Transfer Mode") has been developed to allow simultaneous communication based on different communication modes, in a 2G or 2.5G network, with reduced complexity. This functionality is described in the technical specification TS 43.055, version 4.3.0, "Digital cellular telecommunications System (Phase 2+); Dual Transfer Mode (DTM); Stage 2", published in August 2003, by 3GPP ("3rd Generation Partnership Project ").
• DTM DTM-Time Division Multiple Access
• constraints are imposed on the radio resources involved in the two modes of communication for a given mobile terminal. For example, the time slots allocated for the CS mode and for the PS mode are systematically contiguous and are controlled in identical power. Such constraints thus simplify the support of simultaneous communications in different modes by the simplified class A terminals, that is to say the terminals compatible with the DTM functionality.
• the management of communications remains delicate within the framework of the DTM, insofar as it involves coordination between the CS and PS domains, which was not initially planned in the GPRS system. This is why the DTM functionality is generally little available in practice in deployed networks, thus limiting the possibility of communicating simultaneously according to different communication modes in a 2G or 2.5G context.
• the invention thus proposes a method for managing communications in a telecommunication system comprising at least a first and a second subsystem, terminals being able to communicate via the second subsystem according to both a first mode. communication method and a second communication mode, the terminals not being able to communicate via the first subsystem according to both the first communication mode and the second communication mode.
• the method comprises the following steps, relative to a terminal having a first communication in progress with the first subsystem according to the first communication mode: - detecting a request for establishment of a second communication according to the second communication mode for said communication terminal, said establishment request being initiated by said terminal to the first subsystem; - in response to the detection of said request, initiating a transfer of the first communication in progress to the second subsystem; and - establishing a second communication with the second subsystem according to the second communication mode.
• Two simultaneous communications according to two modes of communication can thus be implemented simultaneously for this terminal, by means of the second subsystem which supports such simultaneity.
• the first subsystem can for example be a second generation radiocommunication system, while the second subsystem can be a third generation radiocommunication system.
• the first mode can for example consist of a circuit mode, while the second communication mode can be a packet mode.
• Other modes of communication can also be used in the context of the invention.
• the detection of the establishment request can result directly from the initiation of this request by the terminal.
• this request is sent via a message relating to the "Dual Transfer Mode" functionality mentioned above. It can also be detected at the level of the first subsystem. However, this does not imply the implementation or full support of the DTM functionality.
• the transfer of the first communication in progress to the second subsystem is advantageously initiated, for its part, by one or the other of the terminal or of the first subsystem.
• the invention further provides a telecommunications system comprising a first and a second subsystem, arranged to implement the above method.
• the invention also provides a terminal comprising means for communicating via a second subsystem of a telecommunication system according to both a first communication mode and a second communication mode, the terminal not being not able to communicate via a first subsystem of the telecommunications system according to both the first communication mode and the second communication mode.
• the terminal further comprises: - means for initiating and transmitting to the first subsystem a request to establish a second communication according to the second communication mode, when it has a first communication in progress with the first sub- system according to the first communication mode; and - means for continuing the first communication in progress on the second subsystem, these means being implemented after the means for initiating and for transmitting to the first subsystem a request to establish a second communication according to the second mode of communication have been implemented.
• the access controller comprises, relative to one of said terminals having a first communication in progress with the first subsystem according to the first communication mode, under the control of said access controller: - means for detecting an establishment request a second communication according to the second communication mode for said terminal, said establishment request being initiated by said terminal to the first subsystem; and - means for, in response to a detection of the request to establish a second communication according to the second communication mode for said terminal, initiating a transfer of the first current communication to the second subsystem.
• the simplified 2.5G subsystem illustrated in FIG. 1 includes a base station 10 or BTS ("Base Transceiver Station"), connected to an access controller, otherwise called base station controller 11 or BSC ("Base Station Controller "), itself connected to a core network switch 13 which is an MSC (" Mobile Switching Center ”) if it is in a circuit mode communication context.
• BTS Base Transceiver Station
• BSC Base Station Controller
• MSC Mobile Switching Center
• PCU Packet Controller Unit
• PCU Packet Controller Unit
• the SGSNs 14 and 22 of the 2.5G and 3G subsystems respectively are connected, possibly by means of other switches, to a platform 33 of GGSN ("Gateway GPRS Support Node") type.
• the GMSC 33 allows the interconnection of the heterogeneous telecommunications system with an external network, such as the public switched telephone network 34 (PSTN).
• PSTN public switched telephone network 34
• the GGSN 31 for its part, allows the interconnection of the heterogeneous telecommunication system with an external packet data transmission network 32 or PDN ("Packet Data Network”), such as the Internet network for example.
• PDN Packet Data Network
• a radio terminal 1 or UE User Equipment
• the request to establish such a communication can be transmitted to the 2.5G subsystem on the initiative of a network entity or a remote entity, to establish an incoming call in PS mode (for example a download server 36, connected to PDN 32, seeks to transmit data to the UE 1), or else on the initiative of the UE 1 itself, in order to establish an outgoing call in PS mode (for example the UE 1 wishes to transmit data to a remote terminal in PS mode).
• PS mode for example a download server 36, connected to PDN 32, seeks to transmit data to the UE 1
• the UE 1 wishes to transmit data to a remote terminal in PS mode
• the UE therefore transmits a request to establish a communication in PS mode to the BSC 11 of the 2.5G subsystem.
• the transmission of the request can advantageously be based on existing messages available in the standardized protocol of the DTM functionality.
• the UE 1 can transmit to the BSC 11, on a dedicated signaling channel, a "DTM Request” message, as defined in section 6.1.2.2 of the aforementioned technical specification TS 43.055. This transmission is illustrated in FIG. 2.
• the BSC 11 On reception of this "DTM Request" message, the BSC 11 initiates a procedure for transferring the current communication in CS mode from the 2.5G subsystem to the 3G subsystem. This transfer is a 2.5G-> 3G inter-system handover, as described in section 8.2 of the technical specification TS 23.009, version 5.6.0, "Digital cellular telecommunications System (Phase 2+); Universal Mobile Telecommunications System ( UMTS); Handover procedures ", published in September 2003 by 3GPP.
• the main signaling messages exchanged within the framework of this handover procedure are shown in FIG. 2.
• the UE 1 regularly transmits radio measurements carried out on its serving cell, that is to say relating to signals emitted by BTS 10, and on neighboring cells, in particular relating to signals transmitted by Node B 20.
• the BSC 11 therefore knows that Node B 20 covers a cell on which the UE 1 would be able to continue its communication.
• the BSC 11 transmits a handover request to the MSC 13 on which it depends ("Ho_Required" message in FIG. 2). This request possibly contains information concerning the cell covered by Node B 20.
• This request is then relayed from MSC 13 to an MSC 3G, for example MSC 23, according to a message from the MAP protocol (Mobile Application Part), "MAP_Prep_Handover request ".
• the MSC 23 for its part warns the RNC 21 so that it can establish communication resources, in particular on the Node B 20.
• a response message "MAP_Prep_Handover response” is then transmitted to the MSC 13.
• the latter finally sends a command message HO_command, to tell the UE 1 via the BSC 11 and the BTS 10 to switch to the resources reserved in the 3G subsystem.
• the UE 1 then resumes its communication in CS mode on the 3G subsystem via the Node B 20 and the RNC 21 in particular.
• the request to establish a communication in PS mode was sent by the UE 1 to the BSC 11, the latter transmits it advantageously to the RNC 21 which controls the communications of the UE 1 after the handover procedure.
• the RNC 21 which controls the communications of the UE 1 after the handover procedure.
• the BSC 11 is not able to transmit the information relating to such a request to the RNC 21, it is advantageous for the UE 1 to renew its request for establishing a communication in PS mode to the RNC 21 this time. Since simultaneous communications in CS and PS mode can be implemented in UMTS, the RNC 21 will then respond favorably to the request for establishment of the UE 1. Then, communication in PS mode is established in a conventional manner by the sub- 3G system.
• the problem of the complex implementation of simultaneous communications in CS and PS mode using 2.5G technology has been avoided.
• the UE 1 can send a request to establish a communication in PS mode, while it is in communication in CS mode on the 2.5G subsystem.
• This is all the more easy if the UE 1 uses a "DTM request" message, used in the context of the DTM functionality.
• the complex DTM functionality is however not implemented, since the BSC 11 is content to switch the communication to CS mode in progress on the 3G subsystem, without having to manage two simultaneous communications. .
• the UE 1 therefore does not need to be a class A terminal, nor a simplified class A terminal, that is to say fully supporting the DTM functionality, since only establishment request messages from communication in PS mode ("DTM request") must be able to be transmitted by UE 1 during communication in CS mode.
• DTM request establishment request messages from communication in PS mode
• This user can indeed carry out his two communications simultaneously, once he has switched to 3G.
• the 2.5G subsystem does not need to fully support the DTM functionality, since the current CS communication is transferred to the 3G subsystem before the establishment of the new communication in PS mode, which avoids setting up a complex implementation of the 2.5G subsystem.
• the request to establish a communication in PS mode is transmitted on the initiative of a remote entity (for example a download server 36, connected to the PDN 32) and it is received in the 2.5G subsystem, for example to the BSC 11.
• a remote entity for example a download server 36, connected to the PDN 32
• the BSC 11 On receipt of this request, the BSC 11 behaves as in the case described above.
• the new communication in PS mode can be established without difficulty according to UMTS technology.
• the complexity linked to the implementation of communications in CS and PS mode simultaneously on the 2.5G subsystem is therefore avoided in this case also.
• it is considered that the UE 1 is in communication with the 2.5G subsystem, the communication being carried out in a packet mode.
• the UE has a communication in progress with a remote entity (for example a server 36 of the PDN 32) via the 2.5G subsystem.
• a remote entity for example a server 36 of the PDN 32
• the communication is carried out using GPRS technology, in conjunction with the BTS 10, the BSC 11 and the PCU 12 which controls it. It is also routed to PDN 32 via SGSN 14 and GGSN 31. It is considered, for example, that a new CS type communication must be established for UE 1, already in progress. PS communication with the 2.5G subsystem.
• the request to establish such a communication can be transmitted to the 2.5G subsystem on the initiative of a remote entity, to establish an incoming call in PS mode (for example a terminal 35 seeking to establish a voice communication with the UE 1), or at the initiative of the UE 1 itself, in order to establish an outgoing call in CS mode (in this case it is the UE 1 which seeks to establish a communication voice with an interlocutor).
• PS mode for example a terminal 35 seeking to establish a voice communication with the UE 1
• CS mode in this case it is the UE 1 which seeks to establish a communication voice with an interlocutor
• the transmission of the request can advantageously be based on existing messages available in the standardized protocol of the DTM functionality, for example the "DTM Request” message, mentioned above (see FIG. 3). ).
• the BSC 11 On receipt of this "DTM Request” message, the BSC 11 triggers a procedure for transferring the current communication in PS mode from the 2.5G subsystem to the 3G subsystem. This transfer consists in interrupting the transmission of data in progress on the 2.5G subsystem, by closing the connection, also called TBF ("Temporary Block Flow"), which temporarily carried this transmission, then in re-selecting a 3G cell (in our example the cell covered by Node B 20), before resuming transmission via the 3G subsystem, via Node B 20.
• TBF Temporal Block Flow
• the cell reselection is carried out at the initiative of the network.
• This operating mode controlled by the network is provided in particular by broadcasting or transmitting to the UE 1 the parameter NC2 described in section 10.1.4 of technical specification 145 008, version 5.12.0, "Digital cellular telecommunications System ( Phase 2+); Radio subsystem link control ", published in August 2003 by ETSI.
• the 2.5G subsystem then sends a command to the UE 1 so that the latter re-selects a cell under the control of the 3G subsystem (see paragraph 10.1.4.2 of the aforementioned technical specification 145 008).
• This command called PACKET CELL CHANGE ORDER, as well as the inter-system cell re-selection mechanism are detailed in the technical specification TS 144 060, version 5.8.0, "Digital cellular telecommunications System (Phase 2+); General Packet Radio Service (GPRS); Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control / Médium Access Control (RLC / MAC) protocol ", published in September 2003.
• the mobility procedure continues in the traditional way. A change of location area is notably required by the UE 1, when the choice of re-selection of a 3G cell has been made ("GMM Routing Area Update Request" message in FIG. 3).
• a response is sent to the SGSN 22 by the GGSN 31, when this information is updated ("GTP Response" message in FIG. 3).
• the SGSN 22 also requests the RNC 21 to allocate corresponding resources, so that the transmission in PS mode can resume between the UE 1 and the Node B 20.
• the UE 1 can autonomously re-select the 3G cell covered by the Node B 20. In this case, the network does not therefore ask the UE 1 to carry out such a re-selection , i.e.
• the PACKET CELL CHANGE ORDER message is not transmitted to the UE L It is also not necessary, in this case, to inform the 2.5G subsystem of the request to establish a new communication in CS mode, which amounts to not transmitting from the UE 1 to the BSC 11, via the BTS 10, the message of the type "DTM Request" (the request still exists in this case, but it remains at this stage at EU level 1).
• the re-selection being carried out by the UE 1 when the latter wishes to make an outgoing call in CS mode without an order from the network being necessary, it then suffices for the UE 1 to re-select the cell covered by Node B 20 as described above, then carry out its request to establish a new communication in CS mode once it is in connection with the 3G subsystem. The latter is then able to respond to this request, by allocating communication resources for this new communication, in particular radio resources between the UE 1 and the Node B 20.
• a request for establishing a communication in mode CS was nevertheless sent by the UE 1 bound for the BSC 11 ("DTM Request" message in FIG.
• the latter can advantageously transmit it to the RNC 21 which controls the communications of the UE 1 after the procedure for communication transfer in PS mode in progress.
• the transmission of the request is carried out either directly if there is a communication link between the BSC 11 and the RNC 21, or via switches connecting these entities.
• the BSC 11 receives the request to establish the new communication in CS mode and it reacts to this request by asking the UE 1 to re-select a cell of the 3G subsystem, that is that is, in the example illustrated in FIG. 1, the cell covered by Node B 20. This corresponds to the transmission of the PACKET CELL CHANGE ORDER message to the UE 1, as illustrated in the figure 3. The rest of the procedure is the same as in the case previously described and illustrated in figure 3. Communication in PS mode is alo rs taken up on the cell covered by Node B 20 of the 3G subsystem.
• the request for establishing the new communication in CS mode is transmitted to the RNC 21 which controls the Node B 20, or it is renewed by the entity which transmits it, so as to be received and processed, this time by the RNC 21.
• the latter then allocates resources so that this communication in CS mode can be established, while retaining the transmission in PS mode in progress with the UE 1, as UMTS technology allows. Also in this case, the problem of the complex implementation of simultaneous communications in CS and PS mode using 2.5G technology has been avoided.
• the UE 1 transmits a request to establish a new communication in CS mode, in the advantageous form of the "DTM Request" message usually used within the framework of the DTM functionality, the latter is however not not implemented, since the BSC 11 does not need to manage two simultaneous communications, communication in PS mode in progress with the subsystem 2.5G being transferred to the 3G subsystem, before the new communication in CS mode is established.
• the present invention has been described above in the context of a telecommunication system comprising two subsystems, one of which is a 2.5G type radiocommunication subsystem and the other, a subsystem of 3G type radio communication.
• This embodiment is interesting in particular in the case where a second subsystem of the telecommunication system supports the implementation of simultaneous communications for a given terminal, unlike a first subsystem with which the terminal is in communication and which only supports the implementation of one communication at a time for a given terminal.

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