FR2892592A1 - TUNING OF COMMUNICATION MODES IN A MOBILE NETWORK WHEN CHANGING RADIO COVERAGE - Google Patents

Abstract

Interfaces (IST, ISRR1) connect a terminal (TA) to a radio access network (RRA) connected to a core network (RCA) to a remote terminal (TB). A call service request relating to a first communication mode is transmitted from the terminal to the core network. A management module (GSAR) establishes access support (CD1, CD2) supporting two communication modes and carrying data frames between the terminal and the core network according to the first communication mode. The first communication mode switches to a second communication mode if a communication mode switching criterion is satisfied in order to transport data frames according to the second communication mode with maintenance of the first communication mode between the core network and the terminal. remote.

Description

Switching modes of communication in a mobile network during a

  The present invention relates to management of the switching of video-audio communication modes and vice versa in a mobile-type communication network during a change of radio coverage in the network.

  With reference to FIG. 1, a first mobile terminal TA exchanges video data or audio data with a second mobile terminal TB through a radio access telecommunications network for mobile terminals. This telecommunications network comprises a first local communication network RLA connected to a second remote communication network RB via an intermediate network RI. The first local communication network RLA comprises a first radio access network RRA to which the first terminal TA is connected, and a first core network RCA connected to the first access network RRA and the intermediate network R1. The second remote network RB comprises a second RRB radio access network to which the second terminal TB is connected, and a second core network RCB connected to the intermediate network RI and the second access network RRB. All the first networks RRA and RCA and the set of second networks RRB and RCB are for example UMTS type (Universal Mobile Telecommunications System). During a video communication between the two terminals TA and TB through the telecommunications networks RLA and RB, if the radio coverage of one of the two networks, for example the network of

  RLA local communication, has degraded and is no longer capable of supporting video communication, currently communication switches from end to end of the video communication mode to a degraded communication mode can be either a lower speed video communication or a audio communication. For example, high speed video communication, such as 64 kbit / s is degraded and requires a switch to low bit rate video communication, such as 32 kbit / s, or to one-to-one audio communication. flow rate between 4.75 kbit / s and 12.2 kbit / s. Conversely, if the radio coverage of one of the two communication networks has improved, the communication between the two terminals switches from end to end of the degraded communication mode to the initial communication mode. . The switching of communication modes involves a codec (coder / decoder) or codec parameter switching included in the TA and TB terminals in order to obtain a communication rate better adapted to the propagation conditions in at least one of the networks. RLA, RB, the rate typically ranging from 4.75 kbit / s to 12.2 kbit / s for an audio mode and can be 32 kbit / s or 64 kbit / s for a video mode. The switching of communication modes is managed according to third generation telecommunications standards (3GPP) defined in the UMTS network specifications and including unrestricted digital information and service switching functionality designated by SCUDIF (" Service Change and Unrestricted Digital Fallback Information ". The communication modes switch in the terminals TA and TB by a switching of one

  a video codec to an audio codec or an audio codec to a video codec as well as a change of a radio communication channel specific to the transfer of video data into a radio communication channel specific to the transfer of audio data in each of the networks of communication RLA and RB, or reciprocally. A communication channel is also called Radio Access Bearer (RAB) in the UMTS network specifications. The change of the radio access medium requires exchanges of signaling frames between each core network and the respective access network in order to negotiate a new radio access support adapted to the new radio coverage conditions. Failover of communication modes leads to high codec switching and radio access medium switching times since both communication networks are involved and signaling messages are transmitted end-to-end from the mobile access telecommunications network . In addition, the SCUDIF functionality requires a synchronization of the change of the two codecs for both TA and TB terminals, which means an end-to-end modification of the codecs or their parameters and the radio access supports when the radio conditions have been reached. degraded in one of the two communication networks, despite maintaining satisfactory radio conditions for communicating in video mode in the other communication network.

  The object of the invention is to remedy the aforementioned drawbacks and particularly to make the mode changes of

  communication in the two communication networks during the communication between the two terminals. In other words, the invention aims at performing a communication mode switch in a first communication network whose radio conditions have changed without operating a communication mode switch in a second remote network whose radio conditions are satisfactory. , the communication between the terminals being established via the two communication networks.

  To achieve this objective, to manage a switch from a first communication mode to a second communication mode in a communication network comprising a first terminal, a radio access network and a core network, the method comprising a connection step between the first terminal and the radio access network and a step of transmitting a request for a call service from the first terminal to the core network via the radio access network to communicate with a second terminal according to the first mode of communication, is characterized in that it comprises the following steps. in response to a request from the heart network relating to the requested call service, an establishment by the radio access network of an access medium supporting both modes of communication, a data frame transport between the first terminal and the core network according to the first communication mode via the established access medium, and if a communication mode switching criterion is satisfied, a switching of the

  first communication mode to the second communication mode for transporting the data frames according to the second communication mode between the first terminal and the core network with maintaining the first mode of communication between the core network and the second terminal. One of the advantages of the invention is the maintenance of access support when switching from a first communication mode to a second communication mode in the local communication network. The communication mode switching management in the prior art SCUDIF includes an access support adapted only to a single communication mode. As soon as a change in radio coverage is detected, the core network and the radio access network dynamically renegotiate the communication mode in order to replace the radio access medium supporting the initial communication mode with a radio access medium. supporting a new communication mode more suitable for propagation conditions. Failover management of communication modes according to the invention does not include replacement of access support during the change of radio coverage.

  The communication mode switching management method according to the invention runs only in the communication network whose radio coverage is changed. There is no end-to-end management, thus minimizing the switchover time and the transmission time of signaling frames. According to a characteristic of the invention, the method comprises a conversion in the core network of data frames from the second terminal and relating to the first communication mode into data frames relating to the second mode of data.

  communication and vice versa, so that a remote network comprising the second terminal ignores the communication mode switchover in the communication network.

  According to another characteristic of the invention, the switchover from the first communication mode to the second communication mode in the communication network comprises the following steps: a transmission of a respective communication mode change notification from the access network radio to the first terminal and to the core network, and in response to the notification, a switch in the first terminal of a first codec relating to the first communication mode to a second codec relating to the second communication mode in order to encode / decode the data frames transported in the access medium according to the second communication mode.

  The management of the switching of communication modes has the advantage of minimizing the switching time of the codecs since only the local terminal associated with the communication network whose coverage is modified, switches these codecs.

  According to the invention, the establishment by the radio access network of the access support can comprise the following steps. establishing a first data carrier supporting both communication modes and carrying data frames between the first terminal and the radio access network, and establishing a second data medium supporting both communication modes and carrying data carriers; data frames between the radio access network and the core network.

  The invention also relates to a system for managing a switchover from a first communication mode to a second communication mode in a communication network comprising a first terminal, a radio access network and a core network, the system comprising means for connecting the first terminal to the radio access network, and means for transmitting a call service request from the first terminal to the core network via the radio access network to communicate with a second terminal according to the first mode of communication. The system is characterized in that it comprises means in the radio access network for establishing an access bearer supporting both communication modes and carrying data frames between the first terminal and the core network 20 according to the first communication mode, and means in the communication network for switching from the first communication mode to the second communication mode if a communication mode switching criterion is satisfied to transport the data frames via the access medium. according to the second communication mode between the first terminal and the core network with maintenance of the first communication mode between the core network and the second terminal. The invention relates to a terminal included in a communication network comprising a radio access network and a core network, the terminal comprising means for connecting to the radio access network and means for transmitting a radio access network.

  requesting a heart network call service via the radio access network to communicate with a second terminal in a first communication mode, characterized in that it comprises a means for switching from the first communication mode to a second communication mode, following establishment by the radio access network of an access medium supporting both communication modes, if a communication mode switching criterion is satisfied, in order to transport data frames according to the second communication mode between the first terminal and the core network via the access support with maintenance of the first communication mode between the core network and the second terminal.

  The subject of the invention is also a radio access network included in a communication network comprising a first terminal and a core network, the radio access network comprising means for connecting to the terminal and means for transmitting a request for access. a call service from the terminal to the core network to communicate with a second terminal according to a first communication mode, characterized in that it comprises: means for establishing an access medium supporting the first communication mode and a second communication mode and carrying data frames between the first terminal and the core network according to the first communication mode, and means for switching from the first communication mode to the second communication mode if a communication mode switching criterion is

  satisfied in order to transport the data frames via the access medium according to the second communication mode between the first terminal and the core network with maintenance of the first mode of communication between the core network and the second terminal.

  Finally, the invention relates to a computer program adapted to be implemented in a system for managing a switchover from a first communication mode to a second communication mode in a communication network comprising a first terminal, a a radio access network and a core network, the first terminal and the radio access network being connected and a request for a call service being transmitted from the first terminal to the core network via the radio access network to communicate with a second terminal according to the first communication mode. The computer program is characterized in that it comprises instructions which, when the program is executed in said system, perform the steps according to the method of the invention.

  Other features and advantages of the present invention will appear more clearly on reading the following description of several preferred embodiments of the invention, given by way of non-limiting examples, with reference to the corresponding appended drawings in which: FIG. 1 is a schematic block diagram of a telecommunications network for mobile terminals known already commented; FIG. 2 is a schematic block diagram of a communication network according to the invention;

  FIG. 3 is an algorithm of a method for managing a switching of communication modes in a communication network, according to the invention; FIG. 4 is an algorithm of a method for managing a change of communication modes during a degradation of the radio coverage of the communication network, according to the invention; and FIG. 5 is an algorithm of a method for managing a change of communication modes during an improvement of the radio coverage of the communication network, according to the invention.

  The invention relates to a mobile radio access telecommunications network as described above and shown in FIG. 1. Each RLA, RB communication network comprises at least one mobile terminal TA, TB, an RRA radio access network, RRB and RCA core network, RCB. The radio access networks RRA and RRB are considered in the remainder of the description as UMTS access networks. In a variant, the networks RRA and RRB may be of another type. These radio access networks having similar architectures, only the RRA network has been represented in FIG. 2.

  With reference to FIGS. 1 and 2, and by analogy with the UMTS network specifications, the radio access network RRA is a universal terrestrial radio access network (UTRAN) and comprises at least a radio communication node NA communicating with the terminal TA and controlled by a radio network controller RNCA ("Radio Network Controller" in English). The RCA core network includes a mobile switching service switch (MSCA) for the transmission of information by

  Circuit Switched.

  The terminal TA is for example a personal computer that can communicate with, in particular, the communication network RLA. According to other embodiments, the terminal TA comprises all the functionalities of a mobile cellular radio terminal, including a personal digital assistant PDA communicator or smart phone (SmartPhone), capable of communicating with the fixed network of a mobile network. cellular radiocommunications of the UMTS type. Each communication signaling entity TA, RRA, RCA of the RLA network comprises an interface of respective IST, ISRR1-ISRR2, ISRC for the transmission of signaling frames and an IDRC interface for respective data frames IDT, IDRR1-IDRR2 and the transmission of data frames. The signals contain control information of the communication network RLA, and include informative acknowledgments. video data of the network of user data to be transmitted between the local terminal TA and a remote terminal TB. The video data frames include image and sound components. Audio data frames include only sound components. By analogy with the UMTS network, each IST signaling interface, ISRR1-ISRR2, ISRC is dedicated to the control plane of the TA, RRA, RCA entities, example of the requests, responses and sometimes including data. The data frames include or audio according to the local communication mode RLA and contain

  and each IDT data interface, IDRR1-IDRR2, IDRC is dedicated to the user plane of these same entities. The IDRR1-IDRR2 data interface of the RRA radio access network comprises two data interfaces IDRR1 and IDRR2. The first interface IDRR1 transmits data frames to the terminal TA and receives data frames from the terminal TA. The second IDRR2 interface transmits data frames to the RCA core network and receives data frames from the RCA core network. The ISRR1-ISRR2 signaling interface of the RRA radio access network comprises two ISRR1 and ISRR2 signaling interfaces. The first interface ISRR1 transmits signaling frames to the terminal TA and receives signaling frames of the terminal TA. The second ISRR2 interface transmits signaling frames to the RCA core network and receives signaling frames from the RCA core network.

  The terminal comprises a first codec (coder / decoder) CV dedicated to the video communication mode and a second codec CA dedicated to the audio communication mode. The CV and CA codecs respectively encode frames of video and audio data to be transmitted to the RCA core network via the radio access network RRA and respectively decode frames of video and audio data from the RCA core network. An MCC switch initially positioned on one of the two codecs switches to the other codec, if necessary, when a radio coverage change is detected in particular by a propagation condition detector included in the radio access network RRA.

  In practice in the radio access network RRA, the RNCA radio network controller comprises, in addition to the IDRR1, IDRR2, ISRR1 and ISRR2 interfaces, a DCR propagation condition detector and a GSAR management module. The detector DCR detects a change in radio coverage of the communication network RLA satisfying a communication mode switching criterion corresponding to the crossing of a degradation threshold or a threshold of improvement of the radio conditions. The GSAR management module establishes and manages an access support according to the invention. The access medium is a communication channel responsible for transporting the data frames from the terminal TA to the core network RCA, and vice versa. The access medium is negotiated during the establishment of the communication between the three entities TA, RRA and RCA of the communication network by parameters defined according to a call service requested by the terminal and according to characteristics. hardware and software of the terminal, for example if it includes an MCC switch to support the access medium according to the invention. This access support has the characteristic of supporting all the modes of audio communication and the video mode. The speed of the audio codec CA varies for example between 4.75 kbit / s and 12.2 kbit / s which corresponds to different audio modes associated with adaptive multi-rate modes of the codec AMR ("Adaptive Multi Rate" in English) dedicated speech according to the UMTS network specifications. The video codec bit rate CV can take for example one of the two values 32 kbit / s and 64 kbit / s. Thus, the access medium according to the invention can have a bit rate between a minimum of 4.75 kbit / s and a maximum of 64 kbit / s. Access support includes a

  first data carrier, hereinafter referred to as the "first data channel" description CD1, for carrying data frames between the IDT data interface of the TA terminal and the IDRR1 data interface of the RRA radio access network , and a second data carrier, also referred to in the remainder of the description "second data channel" CD2, for carrying data frames between the IDRR2 data interface of the RRA radio access network and the data interface. IDRC of the RCA core network. The radio access network also manages the establishment of signaling channels for transporting the signal frames between the TA, RRA and RCA entities of the RLA network. A first signaling channel CS1 carries signaling frames between the IST signaling interface of the terminal TA and the first signaling interface ISRR1 of the radio access network RRA. A second CS2 signaling channel carries signaling frames between the second ISRR2 signaling interface of the RRA radio access network and the ISRC signaling interface of the RCA core network.

  In practice in the RCA core network, the MSCA service switch comprises, in addition to the ISRC and IDRC interfaces, an MIT frame processing module. The module can edit frames of video data into a frame of audio data by extracting sound components and vice versa, frames of audio data into a frame of video data by adding image components thereto. This modification aims to maintain the transport of frames of video data in the remote network RB even during the degradation of the

  radio coverage of the local communication network RLA where frames of audio data are then transmitted.

  With reference to FIG. 3, the method for managing the communication mode switching comprises main steps E1 to E3 of negotiation and establishment of access support according to the invention. During these steps, TS signaling frames are transmitted between the IST, ISRR1, ISRR2 and ISRC signaling interfaces of the three entities TA, RRA, RCA of the local communication network RLA and comprise, for example, requests, responses and acknowledgments. Step E1 is divided into substeps E10 to E12 and corresponds to the opening of the first signaling channel CS1 and the second signaling channel CS2 for the exchange of signaling frames TS between the terminal TA and the core network RCA. . In substep E10, the TA signaling interface of the TA transmits a connection request RQC to the ISRR signaling interface of the radio access network RRA. Upon receipt of this request, the radio access network RRA establishes the first signaling channel CS1 between the IST interface of the terminal and the ISRR1 interface of the radio access network, and the second CS2 signaling channel dedicated to the terminal. TA between the ISRR2 interface of the RRA radio access network and the ISRC interface of the RCA core network.

  In the substep E11, the signaling interface ISRR1 of the radio access network RRA transmits an RPC connection response to the signaling interface IST of the terminal TA to inform it that the connection is established.

  In the substep E12, the terminal TA transmits to the access network RRA an acknowledgment of connection AQC which includes user data DU indicating the hardware and software characteristics of the terminal TA. The radio access network RRA reads the data DU and deduces from it that the terminal TA is compatible with the invention, the hardware and software characteristics of the terminal being adapted to the access medium according to the invention.

  By analogy with the UMTS network specifications, all the RQC, RPC and AQC signaling frames are transmitted according to the radio resource control protocol RRC (Radio Resource Contrai) which manages the transfer of the signaling between the terminal TA and the RRA radio access network. Step E2 is divided into substeps E20 and E21 and corresponds to a request to establish a data connection between the terminal TA and the core network RCA according to a specific call service, for example a telecommunication service for video data transfer. In the substep E20, the terminal TA transmits via its IST signaling interface a request for establishment of call service RQSA to the ISRC interface of the core network RCA. The QSAR request includes an IDA of the terminal TA, an IDB of the remote terminal TB with which the terminal TA wishes to communicate and call data BC ("Bearer Capability" in English) signaling the call service to be established; in the previous example, the call service is related to video communication. In substep E21, the heart network RCA transmits to the terminal TA a CONF response confirming the requested call service.

  By analogy with the UMTS network, the previously defined RQSA request and the RPSA response are transmitted via the radio access network according to the CC ("Cali Contrai") call control protocol. The RRA radio access network does not analyze these two QSAR and RPSA signaling frames and is transparent to them. Step E3 is divided into substeps E30 to E36 and corresponds to the establishment of the access medium according to the invention. In substep E30, the RCA core network produces a request for radio access allocation RRA so that the latter allocates to it an access support adapted to the requested call service and to the subscription of the user of the TA terminal. Upon reception of the RQSAR request, the radio access network RRA proceeds to establish the access support according to the invention, corresponding to the software and hardware characteristics of the terminal TA and the core network RCA and comprising the establishment of two data channels CD1 and CD2 in the following steps. The radio access network RRA establishes, in substeps E31 and E32, the first data channel CD1 between the data interface IDT of the terminal TA and the data interface IDRR1 of the radio access network RRA. The network RRA then transmits in the substep E31 a message MEC1 establishment of the channel CD1 TA terminal. The MEC1 message includes characteristics initially selected for transporting the data frames in the CD1 channel, such as the bit rate and the type of data frames, video or audio. The terminal TA acknowledges the message MEC1 by transmitting an acknowledgment message AQEC1 to the substep E32. Associated MEC1 and AQEC1 messages are transmitted between the radio access network

  RRA and the TA terminal according to the radioRRC resource control protocol according to the UMTS network specification. Likewise, the radio access network RRA establishes, in substeps E33 to E36, the second data channel CD2 between the data interface IDRR2 of the radio access network RRA and the data interface IDRC of the core network RCA. . The RRA then transmits to the substep E33, an MEC2 message establishing the CD2 channel to the RCA core network. The MEC2 message includes the characteristics initially selected for transporting the data frames in the CD2 channel, such as the video or audio data rate. On reading the message MEC2, the core network deduces that the access medium is the one defined by the invention and activates the MTT data frame processing module, in the substep E34. In substep E35, the core network RCA transmits to the radio access network RRA an acknowledgment message AQEC2.

  In response to the acknowledgment message AQEC2, the radio access network RRA transmits to the core network RCA an RPSAR response message indicating that the access medium is established. By analogy with the UMTS network specifications, the RQSAR access support allocation request and the associated RPSAR response are transmitted between the RRA radio access network and the RCA core network according to the network application protocol. radio access network application part (RANAP), which is responsible for signaling between the two RRA and RCA entities. The message MEC2 establishing the CD2 channel and the associated acknowledgment AQEC2 are transmitted between the radio access network RRA and the RCA core network according to the Iu-UP protocol which provides the transport of

  information generated by a user and associated with an access medium. In step E4, TDV video data frames are transported between the TA terminal and the RCA core network in the access medium via the RRA radio access network which does not analyze the TDV frames and transmits them as a simple relay to the RCA core network.

  Referring now to FIG. 4, the switching of communication modes during a degradation of the radio coverage of the local communication network RLA comprises main steps E5 and E6. It is assumed that a video mode communication has been established between the local terminal TA and a remote terminal TB through a remote network RB. Step E5 is divided into substeps E50 to E53 and corresponds to detection by the DCR detector of the radio coverage change satisfying a communication mode switching criterion. The failover criterion corresponds to a threshold of degradation of the radio coverage that no longer makes it possible to transport the data frames according to the initial communication mode. In the previous example, the initial communication mode is the video communication. Thus, the GSAR access support management module switches from the video communication mode to the audio communication mode by modifying the characteristics of the data channels CD1 and CD2 so that they carry frames of audio data according to a transport rate. supported by degraded radio coverage, for example a bit rate of 12.2 kbit / s.

  In substep E51, the radio access network RRA transmits via the signaling interface ISRR2 a communication mode switching notification NDC2 in the second data channel CD2 to the core network RCA. Similarly, in the substep E52, the radio access network RRA transmits, through the signaling interface ISRR1, a communication mode switching notification NDC1 in the first data channel CD1 to the terminal TA. In the substep E53, the terminal TA interprets the notification NDC1 to control the switch MCC so that it switches the video codec CV to the audio codec CA which can encode and decode frames of audio data transported in the access medium modified CD1-CD2. The step E6 is divided into substeps E60 to E65 and corresponds to a processing of the data frames in the RCA core network. As indicated schematically in the substep E60, the IDRC data interface of the core network receives frames of TDV video data transmitted by the remote terminal TB through the remote network RB and the intermediate network RI, during the communication with each other. video mode with the local terminal TA. In response to the NDC2 notification, the core network MTT frame processor RCA extracts, at the sub-step E61 simultaneous with the substep E53, sound components in the TDV video data frames, converts them to the mode. audio used, and inserts them into TDA audio data frames. These TDA audio data frames are then transmitted, in the substep E62, to the local terminal TA via the modified access medium CD1-CD2 adapted to the audio mode and are decoded in the terminal by the audio codec CA.

  Conversely, the TDA audio data frames encoded, in substep E63, by the CA audio codec of the terminal TA are converted, in substep E64, into the RCA core network by the MTT frame processor into TDV video data frames in particular by inserting image components into the video data frame. The new frames of TDV video data are transmitted to the terminal TB through the remote network RB, in the substep E65.

  The image components can represent a still image or a short repetitive sequence of moving images.

  With reference to FIG. 5, a main step E7 divided into substeps E70 to E74 and a main step E8 correspond to an improvement of the radio coverage and therefore to the reversal of the communication mode. The DCR detector of the radio access network RRA detects, in the substep E70, an improvement of the radio conditions satisfying the communication mode switching criterion, the radio coverage before the step E7 being improved and being able to transport again frames of video data to the TA terminal. The GSAR access support management module switches from the audio communication mode to the video communication mode by changing the characteristics of the data channels CD1 and CD2 so that they carry frames of video data at a transport rate supported by the improved radio coverage, for example a bit rate of 32 kbit / s. In the substep E71, the radio access network RRA transmits via the signaling interface ISRR2 a notification NAC2 for improving the radio coverage and consequently the change of mode of operation.

  communication in the second CD2 data channel to the RCA core network. Thus, in the substep E72, the MTT frame processing module of the core network RCA stops the conversion of the video data frames transmitted by the remote terminal TB into frames of audio data and the conversion of the audio data frames transmitted by the terminal. local TA frames video data. At substep E73 simultaneous with substep E71, the radio access network RRA transmits to the terminal TA a notification NAC1 for improving the radio coverage and therefore a communication mode switch in the first data channel CD1. In the substep E73, the terminal TA interprets the notification NAC1 to control the switch MCC so that it switches the audio codec CA to the video codec CV. In step E8, user data transported by the access medium between the terminal TA and the terminal TB is again included end-to-end in frames of TDV video data which are encoded and decoded in the video codec. CV.

  The invention described herein relates to a method and a system in a communication network for managing a switching of communication modes. According to a preferred implementation, the steps of the method of the invention are determined by the instructions of a computer program incorporated in the communication system, partly in the terminal and partly in the radio access network and the network. heart. The program includes program instructions which when said program is executed in the system perform the steps of the method according to the invention.

  Accordingly, the invention also applies to a computer program, including a computer program on or in an information carrier, adapted to implement the invention. This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code such as in a partially compiled form, or in any other form desirable to implement the method according to the invention. The information carrier may be any entity or device capable of storing the program. For example, the medium may comprise storage means or recording medium on which is stored the computer program according to the invention, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a USB key, or a magnetic recording medium, for example a diskette (floppy disc) or a hard disk. On the other hand, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention can in particular be downloaded to an Internet type network. Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method according to the invention.

Claims (13)

  1 - Method for managing a switch from a first communication mode to a second communication mode in a communication network (RLA) comprising a first terminal (TA), a radio access network (RRA) and a core network ( RCA), the method comprising a connection step (El) between the first terminal and the radio access network and a step of transmitting (E2) a call service request from the first terminal to the core network via the radio access network for communicating with a second terminal (TB) according to the first communication mode, characterized in that it comprises the following steps. in response to a request from the heart network (E30) relating to the requested call service, an establishment (E3) by the radio access network of an access medium (CD1-CD2) supporting the two communication modes, transporting (E4) data frames between the first terminal and the core network according to the first communication mode via the established access medium, and if a communication mode failover criterion is satisfied, a failover (E5-E6 ) of the first communication mode to the second communication mode for transporting the data frames according to the second communication mode between the first terminal and the core network with maintenance of the first communication mode between the core network and the second terminal.   2 - Process according to claim 1, comprising a conversion (E6) in the core network of data frames from the second terminal (TB) and relating to the first communication mode into data frames relating to the second communication mode and vice versa so that a remote network with the second terminal ignores communication mode switching in the communication network (RLA). Method according to claim 1 or 2, wherein the switching (E5-E6) of the first communication mode to the second communication mode comprises the following steps: a transmission (E51) of a respective notification (NDC1, NDC2) of change of communication mode from the radio access network (RRA) to the first terminal (TA) and to the core network (RCA), and in response to the notification, a switch (E53) in the first terminal of a first codec relating to the first communication mode to a second codec relating to the second communication mode for coding / decoding the data frames transported in the access medium (CD1-CD2) according to the second communication mode. 4 - Process according to any one of claims 1 to 3, wherein the establishment (E3) by the access access radio network comprises the following steps: establishment of a first data carrier (E31 -E32) supporting the two communication modes and carrying data frames between the first terminal (TA) and the radio access network (RRA), and establishing a second data carrier (E33-E35) supporting both communication modes and carrying data frames between the radio access network (RAR) and the core network (RCA). 5 - Process according to any one of claims 1 to 4, wherein upon connection between the first terminal (TA) and the radio access network (RRA), the first terminal transmits user data (DU ) to the radio access network informing that characteristics of the first terminal are adapted to the data carrier (E31-E32) supporting the two modes of communication. A system for managing a switch from a first communication mode to a second communication mode in a communication network (RLA) comprising a first terminal (TA), a radio access network (RRA) and a core network ( RCA), the system comprising means (IST, ISRR1) for connecting the first terminal to the radio access network, and means (IST, ISRC) for transmitting a request for a call service from the first terminal to the network. heart through the radio access network for communicating with a second terminal (TB) according to the first communication mode, characterized in that it comprises: means (GSAR) in the radio access network for establishing a support for access (CD1, CD2) supporting the two communication modes and carrying data frames between the first terminal and the core network according to the first communication mode, and means (GSAR, MCC, MTT) in the communication network for switching the first mode of communication to the second communication mode if a communication mode switching criterion is satisfied in order to transport the data frames via the access medium according to the second communication mode between the first terminal and the core network with the maintenance of the first mode of communication. communication between the core network and the second terminal. The communication system according to claim 6, comprising means (MTT) in the core network for converting data frames from the second terminal (TB) and relating to the first communication mode into frames of data relating to the second mode. and vice versa, so that a remote network comprising the second terminal ignores the communication mode switchover in the communication network (RLA). The communication system according to claim 6, wherein the means for switching from the first communication mode to the second communication mode comprises: means (ISRR1-ISRR2) in the radio access network for transmitting a notification (NDC1, NDC2) respective communication mode change from the radio access network to the first terminal (TA) and to the core network (RCA), and means (MCC) in the first terminal to switch a first codec relative to the first communication mode to a second codec relating to the second communication mode in response to the notification, for coding / decoding the data frames transported in the access medium (CD1-CD2) according to the second communication mode. 9 - A communication system according to any one of claims 6 to 8, wherein the access medium (CD1, CD2) comprises: a first data carrier (CD1) supporting both communication modes and carrying frames of data between the first terminal (TA) and the radio access network (RRA), and a second data medium (CD2) supporting both communication modes and carrying data frames between the radio access network (RRA) and the core network (RCA). 10 - Terminal (TA) included in a communication network (RLA) comprising a radio access network (RRA) and a core network (RCA), the terminal comprising means (IST) for connecting to the radio access network and means (IST) for transmitting a request for a call service to the core network via the radio access network to communicate with a second terminal (TB) according to a first communication mode, characterized in that comprises means (MCC) for switching from the first communication mode to a second communication mode, following establishment by the radio access network of an access medium (CD1-CD2) supporting the two modes of communication, if a communication mode switching criterion is satisfied, in order to transport data frames according to the second communication mode between the first terminal and the core network via the access support with maintenance of the first communication mode between the core network and the second me terminal. 11 - Radio access network (RRA) included in a communication network (RLA) comprising a first terminal (TA) and a core network (RCA), the radio access network comprising means (ISRR1) for connecting to the terminal and means (ISRR1, ISRR2) for transmitting a call service request from the terminal to the core network to communicate with a second terminal (TB) according to a first communication mode, characterized in that it comprises : means (GSAR) for establishing an access medium (CD1, CD2) supporting the first communication mode and a second communication mode and carrying data frames between the first terminal and the core network according to the first communication mode , and means (GSAR) for switching from the first communication mode to the second communication mode if a communication mode switching criterion is satisfied to transport the data frames via the access medium according to the second mode of communication. communication between the first terminal and the core network with maintenance of the first communication mode between the core network and the second terminal. Computer program adapted to be implemented in a system for managing a switchover from a first communication mode to a second communication mode in a communication network (RLA) comprising a first terminal (TA), a network of communication networks radio access (RRA) and a core network (RCA), the first terminal and the radio access network being connected and a request for a call service being transmitted from the first terminal to the core network via the network of radio access for communicating with a second terminal (TB) according to the first communication mode, said program being characterized in that it comprises instructions which, when the program is executed in said system, perform: in response to a request from the network heart (E30) relating to the requested call service, an establishment (E3) through the radio access network of an access medium (CD1-CD2) supporting the two communication modes, a transport (E4) of frames of data between the first terminal and the core network according to the first communication mode via the established access support, and if a communication mode switching criterion is satisfied, a switching (E5-E6) of the first communication mode to the second communication mode; communication for transporting the data frames according to the second communication mode between the first terminal and the core network with maintaining the first mode of communication between the core network and the second terminal. 13 - Recording medium on which is stored a computer program according to claim 12.30