WO2009012665A1

WO2009012665A1 - Method for realizing multimedia call continuity, equipment and system thereof

Info

Publication number: WO2009012665A1
Application number: PCT/CN2008/070648
Authority: WO
Inventors: Zhaohui Zhang; Dongming Zhu; Hengliang Zhang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-07-20
Filing date: 2008-03-31
Publication date: 2009-01-29
Also published as: CN101351039B; CN101351039A

Abstract

A method for realizing multimedia call continuity, equipment and system are provided in the present invention, in which the multimedia call continuity is realized when a user initiates a multimedia call switch from CS domain. The method includes: a switch control function waits for an indication of media channel negotiation completion corresponding to the second access leg after the switch control function receives an establishment request of the second access leg with multimedia attribute initiated from CS domain; the switch control function performs media update with a remote end so that the second access leg replaces the first access leg after receiving the indication of media channel negotiation completion corresponding to the second access leg.

Description

Method, device and system for realizing multimedia call continuity

Technical field

The present invention relates to the field of communications, and more particularly to a method, apparatus and system for implementing multimedia call continuity. Background technique

First, circuit domain voice call

The flow of a general voice call is shown in Figure 1 (the signaling interaction of the network part and part of the backward signaling are omitted in the figure):

1-2. The calling UE initiates a voice call.

3-4. After the called UE receives the voice call, it returns a ringing message;

5-6. The called UE answers the voice call;

7. After the called UE answers, the network opens the two-way transmission channel, and the user can feel the two-way data transmission.

Second, circuit domain multimedia call

The mobile circuit domain (CS domain DOMAIN) multimedia call service is an important service provided by the 3rd Generation Mobile Communication Standard Partner Project (3GPP) starting from the R4 version. This service enables users to perform voice, video, data, etc. The call of the media component.

One of the CS domain multimedia calls differs from the voice in that the calling UE receives the response message (connect) of the peer end, and then uses the MONA process of H.324 Annex K or the H.223 and H.245 protocols defined by ITU-T. Media channel negotiation for multimedia calls in the voice channel, and multimedia data can be transmitted after the negotiation of each logical channel of the multimedia call is completed. Therefore, the user feels that the multimedia data is transmitted and received for a while after accepting the call. The voice call is almost the same as the user feels the transmission of voice data while answering.

The process of establishing a multimedia call in a circuit domain is shown in Figure 2 (the letter omitting the network part in the figure) Let the interaction and part of the backward signaling):

1-2. The calling UE initiates a voice call.

3-4. After the called UE receives the voice call, it returns a ringing message;

5-6. The called UE answers the voice call;

7. The master and the called party negotiate media channels for multimedia calls in the voice channel through the H.223 and H.245 protocols;

8-9. After multiplexing, multiple logical transmission channels are multiplexed in one physical media delivery channel, and the number of processes negotiated according to the media channel is not limited to two.

3. In the current 3GPP network interworking related topics, in order to solve the multimedia call between the CS domain multimedia terminal and the IMS multimedia terminal, the MGCF (Media Gateway Control Function Media Gateway Control Function Entity) / MGW (Media Gateway Function Entity) has been determined as The interworking node performs signaling and media conversion on the CS domain network and the IMS network, so that the CS domain multimedia call and the multimedia call in the IMS can communicate (that is, the CS domain terminal and the IMS terminal initiate a multimedia call to the other party).

When the CS domain network is used as the calling party and the IMS network is called, the MGCF receives the circuit domain call request from the CS domain, and indicates the unrestricted digital information (UDI) and H. The 223 and H.245 requests indicate that the determined call is a multimedia call, and before sending the call request to the IMS side, the SDP information in the IMS is derived according to a default video or audio format supported in the CS domain network, and may be included in the SDP information. Information transfer capability parameters in the CS domain (this parameter includes UDI, H.223, and H.245 request indications). After the call is answered and the media transmission channel is turned on, the MGCF/MGW and the CS domain terminal use the media transmission channel to negotiate the establishment of the multimedia channel. This process may use the MONA process of H.324 Annex K defined by ITU-T or the H.223/H.245 procedure. During and after the media negotiation process, the IMS side may be notified of the media type selected by the MGCF through the CS domain media negotiation process (depending on whether the media attribute negotiated in the H223/H245/MONA process changes, and whether the MGCF is compiled or not). Decoding conversion; no conversion or codec conversion does not initiate media to the IMS side Re-negotiation).

Fourth, the technical solution of the prior art one

Voice Call Continuity (VCC) is a service provided on the IMS network to which the user belongs, enabling the user's voice call to be switched in both directions between the circuit domain (CS domain) and the IMS network. Converged IMS architecture enables access to the network in the CS domain and IP

(IP-Connectivity Access Network IP-CAN) (such as various IEEE 802 series wireless packet access networks, etc.) to achieve seamless voice call service, not only can reduce

The load of GSM/UMTS radio resources can also increase the revenue of operators. As shown in Figure 3, for the 3GPP VCC implementation, a new set of functional entities is added to the IMS domain and the CS domain. They are:

A route redirection entity (CAMEL app) that redirects circuit domain calls to the IMS domain for call anchoring control. In general, it will be combined with gsmSCF (GSM Service Control Function GSM service control function entity) and embodied as an SCP ( Service Control Point) in the circuit domain;

A CS domain adaptation entity (CSAF), which provides a proxy function in the IMS for the VCC terminal to initiate a call or domain handover in the CS domain;

A Domain Selection Control Entity (DSF), which is responsible for making decisions based on various policies such as the user's registration status, call status, and controlling call routing to the selected connection domain in the IMS domain;

A domain handover control entity (DTF), which is responsible for anchoring calls in the IMS domain and performing handover control when handover occurs;

These functional entities are collectively referred to as VCC (Voice Call Continuity) business control entities.

Based on the VCC implementation described above, when the VCC terminal is conducting an active voice session, a domain handover procedure can be initiated to achieve call continuity. In order to enable domain switching, calls initiated or received by the VCC user are anchored to the domain switching processing entity DTF of the IMS network to which the user belongs. DTF is an application server with 3PCC (Third Party Call Control) capabilities. In VCC, the session control leg between DTF and VCC UE is called access leg, DTF. The session control leg between the user and the remote user is called the remote leg. Switching is the replacement of the old access leg (first access leg) in the cut-out network connected to the far leg using a new access leg in the cut-in network. When the remote user's device supports IMS, its bearer connection is replaced end-to-end. When the remote user equipment supports CS/PSTN, the bearer connection is replaced between the VCC UE and the MGW. When the new access leg is fully established, the VCC UE converts the voice bearer from the cut-out domain to the hand-in domain. In general, the VCC terminal can accurately sense the strength of the wireless signals of each access network than the core network. Therefore, the domain handover process with higher delay requirements is initiated by the terminal to the network.

When the user's VCC terminal detects that a wireless signal or the like needs to be switched from the source network to the destination network, the destination network calls a special number (establishing a second access leg, that is, between the DTF and the VCC terminal established in the cut-in network) a new session). The DFA process can be reached by the number call request, and the DTF can determine that it is a domain switch request. According to the media information supported by the VCC terminal in the newly established call and the renegonomic media between the remote user terminals of the original call, the media stream of the remote leg control is redirected to the bearer connection controlled by the second access leg (ie, by updating the remote end) Legs to replace the access leg). After the media negotiation and the new call setup are completed, the call resources in the handover source network are released by the DTF or the VCC terminal (the first access leg is released, that is, the session between the original DTF and the VCC terminal in the network is cut out) . This completes the replacement of the two access legs so that the user's voice call is switched to the destination network. During the handover, the user's voice call remains uninterrupted, which improves the user's service experience.

Figure 4 shows the flow of a call from the IMS to the CS domain in the VCC, including the following steps (some of the non-critical processes have been omitted; some of the entities described by the remote UE are also omitted):

1. The VCC UE determines that the call needs to be switched to the CS domain according to the wireless environment, and calls the special number VDN in the CS domain to switch from the domain.

2. The VMSC redirects the call to the PSI number of the IMS network DTF according to the CAMEL service procedure, so the call can be routed to the DTF processing of the VCC user's home IMS network.

3. The DTF determines the domain switching request destination domain information according to the number in the INVITE. And according to The calling information locates the anchored session.

4-8, the DTF proxy user and the remote user renegotiate the media of the far leg (DTF to remote UE) using the media information in the handover request.

9. After the session establishment of the destination network is completed, the DTF releases the access part of the VCC user in the IMS domain (which may also be a terminal-initiated release, where the DTF release in the network is taken as an example).

During the process of the invention, the inventor found that if the multimedia session is switched to the CS domain, the following problem exists: After the call is answered on the second access leg in the CS domain, the media channel negotiation of the CS domain multimedia call is started. The existing VCC switching process will result in complete interruption of multimedia communication content for a period of time. Therefore, it greatly affects the user's business experience. Summary of the invention

Embodiments of the present invention provide a method, apparatus, and system for implementing multimedia call continuity, which implements continuity of a multimedia call when a user initiates a multimedia call handover from a CS domain.

A method for implementing the continuity of the multimedia call according to the embodiment of the present invention includes the following steps: after receiving the establishment request of the second access leg with the multimedia attribute initiated by the CS domain, the handover control entity waits for the second access leg to correspond to After the media channel negotiation is completed, the switching control entity receives the media channel negotiation completion instruction corresponding to the second access leg, and performs media update with the remote end to replace the second access leg with the first access leg.

A handover control entity according to an embodiment of the present invention includes: a receiving unit, configured to receive from

a request for establishing a second access leg with a multimedia attribute initiated by the CS domain; a holding unit, configured to keep the receiving unit from receiving the establishment request of the second access leg, and waiting for the media channel negotiation corresponding to the second access leg And the switching unit is configured to: use the indication that the holding unit receives the media channel negotiation corresponding to the second access leg as a trigger condition, and perform media update with the remote end, so that the second access leg replaces the first access leg.

A multimode terminal supporting multimedia call switching according to an embodiment of the present invention includes: And a notification unit, configured to: after the sensing unit senses a completion event of the media channel negotiation corresponding to the second access leg, issue a second access leg corresponding to the completion event of the media channel negotiation corresponding to the second access leg; The instructions for the completion of the media channel negotiation.

The media gateway control function entity of the embodiment of the present invention includes: a sensing unit, configured to perceive a completion event of a media channel negotiation corresponding to the second access leg; and a notification unit, configured to: the sensing unit senses the second access leg correspondingly After the completion of the media channel negotiation, an indication of completion of the media channel negotiation corresponding to the second access leg is issued.

The embodiment of the present invention further provides a CS domain adaptation entity, including: a first receiving unit, configured to receive a notification message in a USSD or SMS manner, where the notification message is used to notify that a second access is to be established in a boosted manner. a second receiving unit, configured to receive a media negotiation request, an identifying unit, configured to determine, according to the session identifier in the USSD or the SMS, that the received media negotiation request is an upgrade request, and a converting unit, configured to send the upgrade request Converted to the establishment request of the second access leg.

A system for implementing continuity of a multimedia call in a circuit domain according to an embodiment of the present invention includes: a multimode terminal supporting multimedia call handover, configured to initiate a setup request for a second access leg having a multimedia attribute from a CS domain, and After the completion event of the media channel negotiation corresponding to the second access leg, the indication of completion of the media channel negotiation corresponding to the second access leg is sent; the remote terminal is configured to cooperate with the completion of the media update; and the handover control entity is configured to receive After the establishment request of the second access leg with the multimedia attribute initiated by the CS domain, waiting for the indication of the completion of the media channel negotiation corresponding to the second access leg; and completing the negotiation of the media channel corresponding to the second access leg After the indication, the media update is performed with the remote terminal to replace the second access leg with the first access leg. Another system for implementing circuit domain multimedia call continuity according to an embodiment of the present invention includes: a multimode terminal supporting multimedia call handover, for initiating a request for establishing a second access leg with a multimedia attribute from a CS domain; a control function entity, configured to send an indication that the media channel negotiation corresponding to the second access leg is completed after the completion of the media channel negotiation completion event corresponding to the second access leg; the remote terminal is configured to cooperate with the completion of the media update; a control entity, configured to wait for a media channel corresponding to the second access leg after receiving the establishment request of the second access leg with the multimedia attribute initiated from the CS domain After the negotiation is completed, the media update is performed with the remote terminal after receiving the indication that the media channel negotiation of the second access leg is completed, so that the second access leg replaces the first access leg.

A switching system according to an embodiment of the present invention includes: a handover control entity, configured to receive from

After the establishment request of the second access leg with the multimedia attribute initiated by the CS domain, waiting for the indication of the completion of the media channel negotiation corresponding to the second access leg; and receiving the indication that the media channel negotiation corresponding to the second access leg is completed Afterwards, the switching entity is instructed to perform the switching. The switching entity is configured to perform media update with the remote terminal after receiving the handover indication sent by the handover control entity, so that the second access leg replaces the first access leg.

In the embodiment of the present invention, after receiving the setup request of the second access leg with the multimedia attribute initiated by the CS domain, the handover control entity does not immediately perform media update with the remote end, but waits for the media corresponding to the second access leg. The indication that the channel negotiation is completed; after the handover control entity receives the indication that the media channel negotiation of the second access leg is completed, the media update is started with the remote end, so that the second access leg replaces the first access leg. Therefore, the continuity of the multimedia call is realized when the user initiates the switching of the multimedia call from the CS domain. DRAWINGS

Figure 1 is a flow chart of an existing voice call;

2 is a flow chart of establishing a multimedia call in an existing circuit domain;

Figure 3 is a schematic diagram of an existing VCC architecture;

4 is a flow chart of a call from an IMS to an CS domain in an existing VCC;

FIG. 5 is a flowchart of steps of a method according to an embodiment of the present invention;

6 is a schematic structural diagram of a handover control entity according to an embodiment of the present invention;

7 is a schematic structural diagram of a multimode terminal supporting multimedia call handover according to an embodiment of the present invention; FIG. 8 is a schematic diagram of a first 10 channel conversion unit switching media channel in a multimode terminal supporting multimedia call switching according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a media gateway control function entity according to an embodiment of the present invention; Figure 10 is a flowchart of Embodiment 1 of the present invention;

Figure 11 is a flowchart of Embodiment 2 of the present invention;

Figure 12 is a flowchart of Embodiment 3 of the present invention;

Figure 13 is a flowchart of Embodiment 4 of the present invention;

Figure 14 is a flowchart of Embodiment 5 of the present invention;

Figure 15 is a flowchart of Embodiment 6 of the present invention;

Figure 16 is a flowchart of Embodiment 7 of the present invention;

FIG. 17 is a schematic structural diagram of a handover system according to an embodiment of the present invention. detailed description

In order to implement the continuity of the multimedia call when the user initiates the switching of the multimedia call from the CS domain, the embodiment of the present invention provides a method, device and system for implementing the continuity of the multimedia call, including: switching to a new CS multimedia session, And switching to an existing CS domain voice session, thus forming a CS multimedia session.

As shown in FIG. 5, an embodiment of the present invention provides a method for implementing continuity of a multimedia call, including the following main steps:

Sl. The handover control entity receives a setup request for a second access leg with a multimedia attribute initiated from the CS domain.

The handover control entity determines that the received setup request of the second access leg is initiated from the CS domain according to one of the following ways:

- The handover control entity determines according to the called number in the request (in this case, the called number has an association relationship with the CS domain, and is sent by the network to the terminal before the handover).

The handover control entity determines based on the content of the access domain information in the request.

- According to the default rule, the access domain information is not carried in the request, and the handover control entity determines that the request is initiated from the CS domain.

Wherein, the handover control entity determines the received second according to one or any combination of the following manners The access leg establishment request has multimedia attributes:

- The handover control entity determines based on the SDP information in the request.

- The handover control entity determines based on the called number in the request (in this case, the called number and the media type have an association relationship, and are sent by the network to the terminal before the handover).

- The handover control entity determines the bearer capability value of the UE in the CS domain based on the UE that initiated the request. Specifically, the handover control entity obtains the bearer capability value of the UE initiating the request in the CS domain by: triggering the smart service in the CS domain, and transmitting the bearer capability value of the UE in the CS domain to the IMS domain. The handover control entity obtains the bearer capability value in the process of forwarding the bearer capability value in the IMS domain; or writes the CS domain bearer capability value into the SDP of the SIP call request by using the MGCF, and the request is forwarded in the IMS network. The handover control entity acquires the bearer capability value.

S2. Unlike the multimedia call switching from the CS access network to the IMS network and the voice call being switched from the IMS to the CS access network, the handover control entity maintains the update process of the remote leg and waits for the media corresponding to the second access leg. The indication that the channel negotiation is complete.

Before the handover control entity receives the indication that the media channel negotiation of the second access leg is completed, the handover control entity searches for the media on the second access leg according to the remote media information saved in the first access leg establishment process. The negotiation request (including the SDP offer in the initial access leg establishment request) is responded; the media information includes the media data receiving address of the far end and the media type supported by the far end. In this way, the success of subsequent multimedia channel negotiation and the success rate of the terminal negotiating with the remote UE media on the second access leg can be ensured. At the same time, in order to ensure the security of the handover control entity, the handover control entity sets a timer for waiting for the completion of the media channel negotiation, and rejects the handover when the indication is not received within a certain period of time, releasing the relevant handover or the entire call. The timer may be started after the second access leg is established (ie, the handover control entity sends a SIP 200 OK message on the second access leg), and is released after receiving the indication that the media channel negotiation is completed or timeout.

S3. The handover control entity receives an indication that the media channel negotiation corresponding to the second access leg is completed. After the negotiation of the media channel corresponding to the second access leg is completed, the MSC UE and the MGCF participate in the CS multimedia channel negotiation process, so that the negotiation can be perceived. Therefore, the MGCF may send an indication to the handover control entity that the media channel negotiation is completed by the second access leg; or the MSC UE sends an indication to the handover control entity that the media channel negotiation corresponding to the second access leg is completed.

Specifically, in the actual deployment, if the indication is sent by the MGCF, the MGCF may be delivered in one of the following manners, and the handover control entity learns the media channel negotiation completion event corresponding to the second access leg in a corresponding manner:

- MGCF notifies by SIP INFO message, which carries the indication (which is indicated by extending the SIP header field, method, message body); correspondingly, after receiving the message from the second access leg, the handover control entity detects the carrying The instructions are informed of the completion event.

- MGCF notifies by SIP Notify message, which carries the corresponding extended parameter representation (this method requires the handover control entity to subscribe to the user's CS multimedia channel negotiation completion event); correspondingly, the handover control entity receives from the second access leg After the message, the indication carried by it is detected to know the completion event.

- MGCF sends a SIP RelNVITE/Update message notification to the DTF, and sets the media attribute from INACTIVE to ACTIVE (previously when the MGCF receives the establishment request of the second access leg initiated by the MSC UE, the media attribute is set to INACTIVE Correspondingly, after receiving the message from the second access leg, the handover control entity detects that the media attribute of the second access leg is ACTIVE to learn the completion event.

Specifically, in the actual deployment, if the indication is sent by the MSC UE, the MSC UE is sent in one of the following manners, and the handover control entity learns the media channel negotiation completion event corresponding to the second access leg in a corresponding manner:

- the MSC UE notifies via the SIP Notify message on the first access leg, which carries the corresponding extended parameter representation (this method requires the handover control entity to subscribe to the user's CS multimedia channel negotiation completion event); correspondingly, the handover control entity After receiving the message on the first access leg, The indication carried by the agent is detected to know the completion event.

- the MSC UE is notified by a SIP INFO message, which carries a corresponding indication (the indication is extended by extending the SIP header field, the method); correspondingly, after the handover control entity receives the message from the first access leg, The indication carried by the agent is detected to know the completion event.

- ^18 (1^ is indicated by 80 ^} 8¥ on the first access leg (may be carried with an extended indication or not carrying); correspondingly, the handover control entity receives the message from the second access leg or The indication carried in the message is detected to know the completion event.

S4. The switching control entity performs media update with the remote end to replace the second access leg with the first access leg.

After step S4, the resources occupied by the first access leg may also be released. Specifically, after the MSC UE detects that the media channel negotiation is completed, the MSC UE initiates a release request on the first access leg, and after the handover control entity receives the release request and confirms that the remote access terminal is replaced, the first connection is released. After the switching control entity and the remote end complete the access leg replacement, the release request is initiated on the first access leg, and after receiving the release request, the MSC UE cooperates with releasing the corresponding resource of the first access leg. .

In the embodiment of the present invention, the first access leg and the second access leg are respectively located on different terminals, or the first access leg and the second access leg are located on the same terminal.

In the embodiment of the present invention, if the media channel negotiation of the second access leg fails, the UE that initiates the second access leg establishment request may initiate a release request of the second access leg, and the network receives the release request of the second access leg. After that, the second access leg is released and the first access leg is retained. Thereby ensuring the continuity of the multimedia call.

The embodiment of the present invention further provides a handover control entity. As shown in FIG. 6, the method includes: a receiving unit, a holding unit, and a switching unit. Further, the receiving unit further includes: a first determining subunit and a second determining unit.

And a receiving unit, configured to receive a setup request of a second access leg with a multimedia attribute initiated from the CS domain. The first determining subunit, configured to determine, according to one of the following manners, that the received request for establishing the second access leg is initiated from the CS domain:

The first determining subunit determines according to the called number in the request;

The first determining subunit determines according to the content of the access domain information in the request;

If the request does not carry the access domain information, the first determining subunit determines that the request is from

The CS domain is initiated.

The second determining subunit is configured to determine, according to one of the following manners, that the received request for establishing the second access leg has a multimedia attribute:

The second determining subunit determines according to the SDP information in the request;

The second determining subunit determines according to the bearer capability value of the UE initiating the request in the CS domain; the second determining subunit determines according to the called number in the request.

And a holding unit, configured to: keep the receiving unit receiving the establishment request of the second access leg, and wait for an indication that the media channel negotiation corresponding to the second access leg is completed.

And a switching unit, configured to perform, by the holding unit, an indication that the media channel negotiation corresponding to the second access leg is completed as a trigger condition, and perform media update with the remote end, so that the second access leg replaces the first access leg. The switching unit may be separately mapped to one application server in the IMS network, and the receiving unit and the holding unit are jointly mapped to another application server in the IMS network, and communicate with each other through the IMS network using the SIP protocol; these units may also be mapped together The same application server to the IMS network communicates with each other using the internal interface.

Further, when the switch to the existing voice session in the CS, the receiving unit may include: an identifying subunit, configured to determine, according to the session identifier in the notification received from the IMS network where the media to be switched is located, The media negotiation request is an upgrade request, and the request is used as the establishment request of the second access leg in combination with the notification information in the IMS network.

Further, in order to ensure the security of the handover control entity, the handover control entity may further include: a timing unit, configured to start a timer after determining that the second access leg is established, and instruct the holding unit to wait for the second connection within the timing time. The indication of the completion of the media channel negotiation corresponding to the leg. The embodiment of the present invention further provides a multi-mode terminal that supports multimedia call handover, that is, the MSC UE in the embodiment of the present invention, which includes: a sensing unit and a notification unit; and further includes at least an initiating unit and a first 10-channel conversion One of the unit and the second 10-channel conversion unit. Referring to FIG. 7, an example includes a sensing unit, a notification unit, an initiating unit, and a first 10-channel conversion unit.

And an initiating unit, configured to initiate, from the CS domain, a request for establishing a second access leg having a multimedia attribute.

The sensing unit is configured to sense a completion event of the media channel negotiation corresponding to the second access leg. Since the multimode terminal supporting multimedia call handover participates in the CS multimedia channel negotiation process, the sensing unit can sense whether the negotiation is completed.

The notification unit is configured to send an indication that the media channel negotiation corresponding to the second access leg is completed after the sensing unit senses the completion event of the media channel negotiation corresponding to the second access leg. Specifically, the notification unit sends an indication that the media channel negotiation corresponding to the second access leg is completed by one of the following manners: the notification unit is notified by the SIP Notify message on the first access leg, where the corresponding extended parameter representation is carried The mode needs to switch the control entity to the CS multimedia channel negotiation completion event of the previously subscribed user). The notification unit is notified by a SIP INFO message, which carries a corresponding indication (the indication is extended by extending the SIP header field, the method). The notification unit is indicated by the SIP BYE on the first access leg (it may also carry an extended indication or not carry).

a first 10-channel conversion unit, configured to: after the sensing unit senses that the media channel negotiation of the second access leg is completed, convert the 10-channel between the multi-mode terminal and the user from the bearer connection controlled by the first access leg to The bearer connection is controlled with the second access leg to cooperate with the multimedia user data to continue communication with the remote end through the control of the second access leg and the remote leg after the handover is completed. Specifically, the voice call is taken as an example. Referring to FIG. 8 , the first 10-channel conversion unit is configured to convert the media channel (10 channels) between the multi-mode terminal and the user from the media channel controlled by the first access leg to the second channel. The media channel connection (ie, bearer connection) controlled by the access leg, the conversion of the multimedia channel is similar. The speaker and microphone can be regarded as the media channel entrance and exit between the user and the multimode terminal. The second 10-channel conversion unit is configured to receive the 10-channel switch after the handover control entity receives the remote leg media update completion indication.

Further, when switching to an existing voice session in the CS, the multimode terminal supporting the multimedia call handover may further include: a detecting unit, a notification unit, and an upgrade request sending unit.

a detecting unit, configured to detect a switching indication;

a notification unit, configured to notify the CSAF in the USSD or SMS manner that the second access leg is to be upgraded in a session, or notify the MGCF in a DTMF manner that the session associated with the DTMF signal is to be upgraded Establishing a second access leg; or establishing a second access leg in a upgrading manner on the session indicated by the notification switching control entity in the IMS network where the medium to be switched is located;

The upgrade request sending unit is configured to send an upgrade request to the CS network side.

The embodiment of the present invention further provides a media gateway control function entity, as shown in FIG. 9, which includes: a sensing unit and a notification unit.

The sensing unit is configured to sense a completion event of the media channel negotiation corresponding to the second access leg. Since the MGCF participates in the CS multimedia channel negotiation process, the sensing unit can sense whether the negotiation is completed.

The notification unit is configured to send an indication that the media channel negotiation corresponding to the second access leg is completed after the sensing unit senses the completion event of the media channel negotiation corresponding to the second access leg. Specifically, the notification unit sends an indication that the media channel negotiation corresponding to the second access leg is completed by one of the following manners: the notification unit is notified by the SIP INFO message, where the indication is carried (the indication is extended by the SIP header field, the method, the message Body representation). The notification unit is notified by the SIP Notify message, which carries the corresponding extended parameter representation (this method requires the handover control entity to subscribe to the user's CS multimedia channel negotiation completion event). The notification unit uses the SIP RelNVITE/Update notification to transmit the media parameters in the media negotiation result to the DTF after the MGCF detects that the CS multimedia channel has been negotiated. The notification unit sends a SIP to the DTF

RelNVITE/Update message notification, and set the media attribute from INACTIVE to ACTIVE (The media attribute is set to INACTIVE when the MGCF receives the request to establish the second access leg initiated by the MSC UE).

Further, when switching to the existing voice session in the CS, the media gateway control function entity may further include: a converting unit, configured to convert the upgrade request into an IMS network after receiving the upgrade request from the CS network side Medium media negotiation request. Or,

The method may further include: a receiving unit, configured to receive the information notified by the DTMF method and the upgrade request; and an assembling unit, configured to assemble the information notified by the DTMF manner and the information carried in the upgrade request into the second access leg. Create a request.

An embodiment of the present invention further provides a CS domain adaptation entity, including: a first receiving unit, a second receiving unit, an identifying unit, and a converting unit.

a first receiving unit, configured to receive a notification message in a manner of USSD or SMS, where the notification message is used to notify that a second access leg is to be established in a boosted manner;

a second receiving unit, configured to receive a media negotiation request;

An identifying unit, configured to determine, according to the session identifier in the USSD or the SMS, that the received media negotiation request is an upgrade request;

And a converting unit, configured to convert the upgrade request into a setup request of the second access leg.

The embodiment of the invention further provides a system for implementing multimedia call continuity in a circuit domain, comprising: a multimode terminal supporting a multimedia call handover, a remote terminal, and a handover control entity.

A multimode terminal supporting a multimedia call handover, configured to initiate a setup request of a second access leg with a multimedia attribute from the CS domain, and send a second connection after sensing a completion event of the media channel negotiation corresponding to the second access leg The indication of the completion of the media channel negotiation corresponding to the leg.

The remote terminal is used to complete the media update.

a handover control entity, configured to wait for an indication of completion of media channel negotiation corresponding to the second access leg after receiving the establishment request of the second access leg with the multimedia attribute initiated from the CS domain; and receiving the second connection After the media channel negotiation corresponding to the leg is completed, the media update is performed with the remote terminal to replace the second access leg with the first access leg. The embodiment of the present invention further provides another system for implementing circuit domain multimedia call continuity, including: a multimode terminal supporting a multimedia call handover, a media gateway control function entity, a remote terminal, and a handover control entity.

a multimode terminal supporting multimedia call handover, configured to initiate a setup request for a second access leg having a multimedia attribute from a CS domain;

The media gateway control function entity is configured to: after the completion of the media channel negotiation completion event corresponding to the second access leg, issue an indication that the media channel negotiation corresponding to the second access leg is completed;

The remote terminal is configured to cooperate with the completion of the media update;

a handover control entity, configured to wait for an indication of completion of media channel negotiation corresponding to the second access leg after receiving the establishment request of the second access leg with the multimedia attribute initiated from the CS domain; and receiving the second connection After the media channel negotiation corresponding to the leg is completed, the media update is performed with the remote terminal to replace the second access leg with the first access leg.

The following is specifically described by three embodiments.

[Embodiment 1] The procedure for the multimedia call to be handed over from the IMS to the CS domain; the MGCF notifies the CS domain multimedia channel of the negotiation completion event and the media negotiation mode (in this flow, the CS domain and the IMS part of the MSC UE may also be distributed in different terminals. The process is initiated by the DTF, or the MSC UE initiates the release; the visited mobile switching center in this process may also be combined with the media gateway control function)

The MSC UE has already conducted a multimedia session with the remote UE in the IMS and completed the anchoring in the DTF. The multimedia call continuity process when switching to the CS domain, as shown in Figure 10, includes the following steps:

1 . The MSC UE detects that the multimedia call needs to be switched to the CS domain, and establishes a second access leg in the CS domain.

La, the optional MGCF sets the local port attribute to INACTIVE in the request. 2. The second access leg setup request is routed to the DTF process of the user's home IMS network (the route uses the technology directly routed to the DTF in the VCC, and may also use the VCC involved in it) It is routed).

3. The DTF determines that the call handover direction is switched from the IMS to the CS domain according to the called number or the access domain information in the request, and the access domain where the first access leg is associated; and according to the SDP information in the request The called number or the CS bearer capability information obtained in Embodiment 3 determines that the second access leg belongs to the multimedia call; and the multimedia call is switched from the CS access network to the IMS network and the voice call is switched from the IMS to the CS access network. Therefore, the DTF judges that the call leg between the remote UE and the remote UE is not updated, but waits for the completion of the negotiation of the CS domain multimedia channel corresponding to the second access leg.

4. The DTF uses the saved media information of the remote UE and the second access leg to negotiate the media, and returns the remote receiving port in the response (in the process, the DTF can also set the attribute of the remote receiving port to INACTIVE). Or Send Only, to prevent the MGCF from transmitting data in the media channel to the remote end before the CS domain multimedia channel negotiation and the supported media information. In this way, the success of subsequent subsequent multimedia channel negotiation and the success rate of the terminal negotiating with the remote UE media on the second access leg can be ensured.

After the second access leg is established, neither the MSC UE nor the DTF initiates the release of the first access leg, and the DTF waits for the second access leg to correspond to the completion of the CS domain multimedia channel negotiation. The MSC UE continues to provide data transmission and reception on the 10 channels of the first access leg, and prepares to perform multimedia channel negotiation on the bearer connection corresponding to the second access leg. Meanwhile, in order to ensure the security of the DTF, the DTF sets a wait. The timer for releasing the message releases the related resources of the current handover or the entire call when the message is not received within a certain period of time; the timer may be after the second access leg is established (ie, the DTF is in the second connection) Send a SIP 200 OK message on the leg) Start, release after receiving the notification message from the MGCF on the first access leg or timeout.

6. Perform CS domain multimedia channel negotiation on the bearer connection corresponding to the second access leg. (In this process, the MGCF may initiate media re-negotiation with the remote media according to the result of the CS domain multimedia channel negotiation. Before the DTF detects the CS domain multimedia channel negotiation completion event, the DTF will perform media negotiation between the proxy remote end and the MGCF.) 7. After the negotiation process in the CS domain ends, the MGCF notifies the DTF by using SIP RelNVITE/UPDATE (the SIP header field or the SIP method or the SIP message body can be extended to carry the information, and there is no extension in this example; SIP Notify notification can also be used. DTF, provided that the DTF has subscribed to the media channel negotiation completion event in the CS domain before the handover, so the MGCF can issue the notification; other SIP messages, such as Info notification to the DTF, can also be used.

8. The DTF detects the media channel negotiation completion event (such as receiving the media negotiation completion indication carried in the extended SIP signaling, or changing the media attribute of the receiving port of the second access leg to ACTIVE or Send Receive according to the MGCF indication) And the proxy MSC UE and the remote UE re-negotiate the media of the remote leg by using the media information in the second access leg establishment request (the MGCF may also pass the CS network signaling after receiving the 200 OK response of the RelNVITE sent by the MGCF. The MSC UE is instructed to perform a 10-channel handover, and the MSC UE receives 10 channels after receiving it.

9. After the remote leg update is completed, the DTF releases the first access leg of the IMS domain (which may also be a terminal-initiated release, where the DTF release in the network is taken as an example). At this time, the MSC UE transfers the 10 channels of the media from the bearer connection controlled by the first access leg to the bearer connection controlled by the second access leg (the 10 channel switch can also detect the inband in the MSC UE) After the media channel negotiation is completed).

[Embodiment 2] The procedure for the multimedia call to be switched from the IMS to the CS domain; the UE notifies the CS domain multimedia channel negotiation completion event (in this process, the CS domain and the IMS part of the MSC UE may also be distributed on different terminals; The UE initiates the release as an example, or the DTF initiates the release; the visited mobile switching center in this process may also be combined with the media gateway control function)

The MSC UE has already conducted a multimedia session with the remote UE in the IMS and completed the anchoring in the DTF. The multimedia call continuity process when switching to the CS domain, as shown in Figure 11, includes the following steps:

2, the second access leg establishment request is routed to the DTF processing of the user's home IMS network (the Routing uses the technology in VCC, and other routing methods involved in VCC can also be used.

4. The DTF uses the saved media information of the remote UE and the received media information and the second access leg to negotiate the media, and returns the remote receiving port in its response (in the process, the DTF can also attribute the port) Set to INACTIVE or Send Only to prevent the MGCF from transmitting data from the media channel to the far end before the CS domain multimedia channel negotiation and the supported media information. In this way, the success of subsequent subsequent multimedia channel negotiation and the success rate of the terminal negotiating with the remote UE media on the second access leg can be ensured.

After the establishment of the second access leg, the MSC UE and the DTF do not initiate the release of the first access leg, and wait for the second access leg to correspond to the completion of the negotiation of the CS domain multimedia channel. The MSC UE continues to provide data transmission and reception for the user in the 10 channels of the first access leg, and is ready to perform multimedia channel negotiation on the bearer connection corresponding to the second access leg.

6. Perform CS domain multimedia channel negotiation on the bearer connection corresponding to the second access leg. (In this process, the MGCF may also initiate media re-negotiation with the remote media according to the result of the CS domain multimedia channel negotiation. Before the DTF detects the CS domain multimedia channel negotiation completion event, the DTF will perform media negotiation between the proxy remote end and the MGCF)

7. In this example, after the negotiation process of the MSC UE in the CS domain ends, the first access leg release message is used to notify the DTF. Here, the SIP BYE message is used as an example, and other SIP messages and methods, such as Notify, Info notification, may also be used. To the DTF event; when only the media cut out from the first access leg is released, it can be done using the SIP protocol UPDATE or RelNVITE); In order to ensure the security of the DTF, the handover control entity sets a timer waiting for the release message, and releases the relevant resources of the handover or the entire call when the message is not received within a certain period of time; the timer can be in the second connection. After the leg is established (ie, the DTF sends a SIP 200 OK message on the second access leg), it is released, and is released after receiving the release message or timeout of the MSC UE on the first access leg.

8. After the DTF receives the media negotiation completion indication, the proxy MSC UE and the remote UE re-negotiate the media of the remote leg by using the media information in the second access leg establishment request. (If the remote receiving port attribute is set to INACTIVE or Send Only in step 4, use SIP message to indicate to MGCF to change this attribute to ACTIVE or Send Receive after this step)

9. After the remote leg update is completed, the DTF confirms to the MSC UE to release the first access leg of the IMS domain (the release process may also be a release initiated by the DTF, where the MSC UE release in the network is taken as an example); The UE transfers the 10 channels of the media from the bearer connection controlled by the first access leg to the bearer connection controlled by the second access leg (the 10 channel switch can also detect the media channel in the band detected by the MSC UE) After completion).

[Embodiment 3] Transmission of CS domain bearer capability information, CAMEL triggering mode, see figure

12, including the following steps:

The terminal initiates a multimedia call in the CS domain, where the bearer capability information of the CS domain is represented.

2. The visited mobile switching center VMCS domain reports the indication to the CAMEL business entity during the CAMEL redirection process.

3. The CS domain routes the call to the MGCF for processing according to the redirected called number.

4. The MGCF routes the call to the Circuit Domain Adaptation Entity (CSAF) based on the called number. The CSAF obtains the information from the CAMEL service entity according to the internal interface, and fills the information into the header field or the message body (such as SDP) in the SIP call request message, and continues to route in the IMS network.

5-6, after the call request message is routed to the DTF, the DTF is based on the added header field or message. The body knows the bearer capability information of the user in the CS domain network.

[Embodiment 4] The manner of the USSD/SMS notification (this embodiment omits part of the prior art signaling, retaining the key part of the invention; this embodiment switches the video session in the IP to the voice session in the CS by IP-CAN (PS) For example, the other media may be switched to the CS call. In this embodiment, the switching source and the destination are in the same user equipment, and may also be located in different user equipments; the CSAF entity may be merged with the handover control entity-DTF; the IMS network entity refers to completion. Various CSCFs required for session control, other entities, etc.)

The MSC UE has already conducted a multimedia session with the remote UE in the IMS and completed the anchoring at the handover control entity. The voice part is connected in the CS network, and other media components are connected in the PS network. The multimedia call continuity process when switching to the CS domain, as shown in Figure 13, includes the following steps:

1 . The user equipment detects the handover indication, including but not limited to receiving the user handover indication or the user equipment itself detects that the handover needs to be performed according to the wireless signal, and uses the USSD/SMS to notify the CSAF that the call is to be switched, where the CSAF is requested. The address can be configured in advance or otherwise set to the user equipment;

2. The end office MSC routes the USSD/SMS message to the CSAF according to the destination address through the CS network.

A, after receiving the message <Note 1>, CSAF waits for the upgrade request in the CS call;

3-6, the MSC UE initiates a SCUDIF process to request the CS network to upgrade the voice call to a multimedia call (for example, the upgrade is only an audio + video component, and may include other methods of upgrading), and the network passes through the office. Inter-signaling, such as a BICC message, sends the request to the MGCF, and the MGCF converts the upgrade to a media negotiation request in the IMS network according to the interworking process (the upgrade is also expressed in the IMS network as requesting to add media in the session);

B. The CSAF determines that the request is a pending upgrade request according to the session identifier in the USSD/SMS; the CSAF combines the received USSD/SMS information with the upgrade request using the SIP header field or method or the message body to assemble a SIP handover request. (For example, here is RelNVITE, it can also be Other SIP messages such as UPDATE 2>);

7-8, the handover request is delivered to the DTF through a call signaling path;

C: The DTF determines that the call handover direction is switched from the IMS to the CS domain according to the called number or the access domain information in the request, and the access domain where the first access leg is associated; and according to the SDP information in the request The called number or the CS bearer capability information obtained in Embodiment 3 determines that the second access leg belongs to the multimedia call; according to the DTF, the call leg between the remote UE and the remote UE is not updated.

9-18, the DTF uses the saved media information of the remote UE and the received media information and the second access leg to negotiate the media, and returns the remote receiving port in the response (in the process, the DTF can also use the port) The attribute is set to INACTIVE or Send Only to prevent the MGCF from transmitting data in the media channel to the far end before the CS domain multimedia channel negotiation and the supported media information. In this way, the success of subsequent subsequent multimedia channel negotiation and the success rate of the terminal negotiating with the remote UE media on the second access leg can be ensured.

D, the subsequent switching process, see step 5 of the embodiment 1 to the end of the process or the fifth step of the embodiment 2 to the end of the process; and the difference between the two embodiments is that the first access leg is released The cut-out media may be a RelNVITE message or an UPDATE message; if the media corresponding to the entire first access leg is released, it is consistent with the processes of the two embodiments.

Note 1: The information conveyed includes any combination of the following specific information:

A. Up-conversion switching indication: indicates that the media on the PS will be switched to the indicated CS call by means of media upgrade;

B. Type of handover: Use the method of A above to indicate that some or all of the media are merged into an existing session of a destination network or switched to a new session;

C. The replaced media identifier: the identifier of the replaced media is used to indicate to the DTF that the media in the anchored user session is to be switched, and may use the session identifier of the media plus the media identifier in the session, or use a global identifier. Indicates that if the media in the entire session is switched, the session identifier is used; D. The identifier of the session between the MSC UE and the CS AF: the destination session corresponding to the CS AF location, including but not limited to the identifier of the IMS part session corresponding to the CS voice call;

Note 2: The switching request includes any combination of the following information:

A. The handover indication may be represented by a specific called number such as a VDI/VDN in the VCC, or may be some header fields, methods, and message bodies in the SIP message. Here, only the called number is used as an example;

B. Type of handover: Use the method of A above to indicate, such as media stream merge to a session switch, etc.;

C. The replaced media identifier: the identifier of the replaced media is used to indicate to the DTF that the media in the anchored user session is to be switched, and may use the session identifier of the media plus the media identifier in the session, or use a global identifier. Indicates that if the media in the entire session is switched, the session identifier is used to indicate;

D. Corresponding media information in the new access leg: carried by the SDP information carried in the access leg established in the cut destination network.

[Embodiment 5] Mode of DTMF/CS enhanced notification (This embodiment omits part of the prior art signaling, retaining the key part of the invention; this embodiment switches the voice in the CS to the voice in the CS by IP-CAN (PS) For example, in the embodiment, the other media may be switched to the CS call. In this embodiment, the switching source and the destination are in the same user equipment, and may also be located in different user equipments. The IMS network entity refers to various CSCFs required for completing session control and other Entity, etc.)

The MSC UE has already conducted a multimedia session with the remote UE in the IMS and completed the anchoring at the handover control entity (DTF). The voice part is connected in the CS network, and other media components are connected in the PS network. The multimedia call continuity process when switching to the CS domain, as shown in Figure 14, includes the following steps:

Al, after the MSC UE detects that a handover is required (including but not limited to receiving a user handover indication or the MSC UE detects that a handover is required according to the wireless signal), the MGMF is used to notify the MGCF that handover is to be performed, and the required information transmitted through the DTMF is <Note 1>; A2a. l, the end office MSC uses the in-band signal to transmit DTMF, that is, the VMSC instructs its own MGW to transmit DTMF information;

A2a.2, after receiving the MGW of the MGCF, using the H248 mechanism to notify the MGCF of the received DTMF information; or

A2b, the VMSC uses the inter-office signaling to transmit the DTMF information, and the MGCF receives the DTMF message through the signaling channel;

A3, the network returns a DTMF response (other DTMF delivery messages are omitted)

A, after receiving the information, the MGCF waits for the upgrade request in the CS call;

A4-a5, the MSC UE initiates the SCUDIF process to request the CS network to upgrade the voice call to a multimedia call (in this embodiment, only the upgrade to the audio + video component is taken as an example, and other methods may be included), and the network passes through the office. Inter- signaling, such as a BICC message, sends the request to the MGCF; bl-b2, the MSC UE initiates a SCUDIF process to request the CS network to upgrade the voice call to a multimedia call (in this embodiment, only the upgrade to audio + video component is taken as an example, The network may also include other methods of ascending), and the network sends the request to the MGCF through inter-office signaling, such as a BICC message, where the signaling of the CS is extended, and the required information is carried therein <Note 1>;

B. The MGCF combines the upgrade switching information received by the mode a or b and the upgrade request to assemble a SIP handover request by using the SIP header field or the method or the message body (here, for example, RelNVITE, or other SIP messages such as UPDATE< Note 2>);

6-7, the handover request is delivered to the DTF through a call signaling path;

8- 13, the DTF uses the saved media information of the remote UE and the received media information and the second access leg to negotiate the media, and returns the remote receiving port in the response (the DTF can also use the port in the process) The property is set to INACTIVE or Send Only to avoid MGCF The cs domain multimedia channel is sent to the far end before the multimedia channel negotiation and the supported media information. In this way, the success of the subsequent subsequent multimedia channel negotiation and the success rate of the terminal negotiation between the second access leg and the remote UE media can be ensured.

B. Type of handover: Obtained from the information transmitted by DTMF, and can be represented by some header fields, methods, and message bodies in the SIP message in the IMS;

C. The replaced media identifier: obtained from the information transmitted by the DTMF, and may be represented by some header fields, methods, and message bodies in the SIP message in the IMS;

D. Corresponding media information in the new access leg: carried by the SDP information carried in the access leg established in the cut destination network. [Embodiment 6] The manner of notifying the DTF in the IP-CAN (PS) (This embodiment omits part of the prior art signaling, and retains the key part of the invention; this embodiment switches the video to CS in the IP-CAN. For example, the voice session is switched to a CS call. In this embodiment, the source and destination of the handover are in the same user equipment, and may also be located in different user equipments. The IMS network entity refers to various CSCFs required for completing session control. And other entities, etc.)

The MSC UE has already conducted a multimedia session with the remote UE in the IMS and completed the anchoring at the handover control entity (DTF). The voice part is connected in the CS network, and other media components are connected in the PS network. The multimedia call continuity process when switching to the CS domain, as shown in Figure 15, includes the following steps:

1 . After the MSC UE detects that a handover is required (including but not limited to receiving a user handover indication or

The MSC UE detects the need to switch according to the wireless signal, and uses the SIP INFO in the session of the IMS network to be switched. (The INFO message is used as an example, and other messages may be used; or through a new session or through Ut interface messaging) passing information <Note 2> to the DTF, wherein the requested DTF address can be configured in advance to the user equipment;

A. After receiving the information, the DTF waits for the upgrade request in the corresponding CS call;

2-3. The MSC UE initiates a SCUDIF process to request the network to upgrade the voice call to a multimedia call (in this embodiment, the upgrade is only an audio + video component, and may also include other methods of upgrading), and the network passes through the interoffice. Signaling such as a BICC message to send the request to the MGCF;

4-5, the MGCF converts the upgrade to a media negotiation request in the IMS network according to the interworking process (the upgrade is expressed as requesting to increase the media), and the request is transmitted to the DTF through the call signaling path;

C. The DTF determines, according to the session identifier in step 1, that the request is the waiting for the upgrade request, and then the DTF according to the called number or the access domain information in the request, and the access of the associated first access leg. The domain determines that the call handover direction is from the IMS to the CS domain; and determines that the second access leg belongs to the multimedia call according to the SDP information in the request, the called number, or the CS bearer capability information obtained in Embodiment 3; The call leg between the remote UE and the remote UE is not updated first;

6- 11 , DTF uses the saved media information of the remote UE and the received media information and the second The access leg negotiates the media and returns the remote receiving port in its response (in this process, the DTF can also set the port's attribute to INACTIVE or Send Only to prevent the MGCF from processing the CS domain multimedia channel before negotiating in the media channel. The data is sent to the far end) and the supported media information. In this way, the success of the subsequent subsequent multimedia channel negotiation and the success rate of the terminal negotiation between the second access leg and the remote UE media can be ensured.

A, the upgrade switching indication: indicates that the media on the PS will be switched to the indicated CS call by means of media upgrade; it may be represented by some header fields, methods, and message bodies in the SIP message;

D. The identifier of the session between the MSC UE and the DTF: the destination session corresponding to the DTF location, including but not limited to the identifier of the IMS part session corresponding to the CS voice call.

In summary, in the embodiment of the present invention, after receiving the setup request of the second access leg with the multimedia attribute initiated by the CS domain, the handover control entity does not immediately perform media update with the remote end, but waits for the second connection. The indication that the media channel negotiation is completed by the leg; the switching control entity receives the media channel negotiation completion instruction corresponding to the second access leg, and then starts media update with the remote end, so that the second access leg replaces the first Access the legs.

Since the embodiment of the present invention does not receive the slave CS domain in the handover control entity as in the prior art After the initiation request of the second access leg with the multimedia attribute is initiated, the media update is performed immediately with the remote end, so before the handover, the user can continuously receive the media stream of the multimedia call from the first access leg; After receiving the indication that the media channel negotiation of the second access leg is completed, the entity performs media negotiation with the remote end to replace the first access leg with the second access leg, and switches the media stream of the multimedia call to the second connection. The bearer is connected to the corresponding bearer connection, so the user can experience continuous multimedia calls throughout the handover process.

Further, in the embodiment of the present invention, the multi-mode terminal MSC UE or the media gateway control function entity MGCF that supports the multimedia call handover can send an indication to the handover control entity that the media channel negotiation corresponding to the second access leg is completed. Therefore, in the embodiment of the present invention, a multimode terminal and a media gateway control function entity supporting multimedia call handover are also provided, and corresponding systems are respectively provided. Thus, embodiments of the invention are better supported.

[Embodiment 7] The procedure for the multimedia call to be switched from the IMS to the CS domain, the adaptation entity receives the reception media channel negotiation completion indication (in the present process, the MGCF only informs the CS domain multimedia channel negotiation completion event and the media negotiation mode as an example, The function of the multi-mode terminal and the remote terminal is the same as that of the first embodiment. The MSC UE may notify the CS domain multimedia channel negotiation completion event through the existing session or other signaling mode of the IMS access. The control function of the multimode terminal, the remote terminal, and the media gateway is the same as that described in Embodiment 2; the CS domain and the IMS part of the MSC UE may also be distributed on different terminals; For example, the MSC UE initiates the release; in this embodiment, the handover control entity and the handover entity are mapped to different application servers to perform corresponding functions and can interact through the IMS network; the visited mobile switching center in this process may also The media gateway control function is unified).

The MSC UE has already conducted a multimedia session with the remote UE under IMS access, and the anchoring is completed in the handover entity. The handover control entity may or may not be in the ongoing session signaling path. The multimedia call continuity process when switching to the CS domain, as shown in Figure 16, includes the following steps:

1 . The MSC UE detects that the multimedia call needs to be switched to the CS domain, and can call in the CS domain. Calling a special called number (which may be a PSI number pointing to the switching entity or switching control entity, both of which may identify the number) to establish a second access leg;

La, the optional MGCF sets the local port attribute to INACTIVE in the request;

2. The second access leg establishment request is routed to the handover control entity of the user's home IMS network (the route uses the PSI to directly route to the handover control entity, and other routing methods may also be used);

3: The handover control entity determines, according to the called number or the access domain information in the request, and the access domain where the first access leg is associated (if the handover control entity is in the signaling path of the existing session) The call handover direction is switched from the IMS to the CS domain; and the second access leg belongs to the multimedia call according to the SDP information in the request, the called number, or the CS bearer capability information obtained in Embodiment 3; The network switches to the IMS network and the voice call is switched from the IMS to the CS access network. The handover control entity determines that the handover request for the second access leg is not initiated to the handover entity, but waits for the second access leg. corresponding

An indication that the CS domain multimedia channel negotiation is completed;

4. The handover control entity uses the saved (if the handover control entity is in the signaling path of the existing session), the media information of the remote UE and the second access leg negotiate the media, and returns the remote receiving port in the response ( In this process, the handover control entity may also set the remote receiving port attribute to INACTIVE or Send Only to prevent the MGCF from transmitting data in the media channel to the remote end before the CS domain multimedia channel negotiation and the supported media information. . In this way, the subsequent success of the subsequent multimedia channel negotiation and the success rate of the terminal negotiation between the second access leg and the remote UE media are ensured; or the SDP negotiation process is completed by using the default manner;

After the establishment of the second access leg, the MSC UE and the handover control entity do not initiate the release of the first access leg, and the handover control entity waits for the indication that the second access leg corresponds to the completion of the CS domain multimedia channel negotiation. The MSC UE continues to provide data transmission and reception on the 10 channels of the first access leg, and prepares to perform multimedia channel negotiation on the bearer connection corresponding to the second access leg. Meanwhile, in order to ensure the security of the handover control entity, the handover control Entity set a wait for this a timer for releasing the message, releasing the related resources of the second access leg establishment or the entire call when the message is not received within a certain period of time; the timer may be after the second access leg is established

(ie, the handover control entity sends a SIP 200 OK message on the second access leg), and is released after receiving the notification message of the MGCF on the first access leg or after timeout;

6. Perform CS domain multimedia channel negotiation on the bearer connection corresponding to the second access leg. (In this process, the MGCF may also initiate media re-negotiation according to the result of the CS domain multimedia channel negotiation. Before the handover control entity receives the CS domain multimedia channel negotiation completion event, the handover control entity performs the proxy remote end and the MGCF. Media negotiation in the second access leg);

After the media channel negotiation process in the CS domain ends, the MGCF uses the SIP RelNVITE/UPDATE to notify the handover control entity (the SIP header field or the SIP method, or the SIP message body can be extended to carry the information, and there is no extension in this example; The SIP control is used to notify the handover control entity, provided that the handover control entity has subscribed to the media channel negotiation completion event in the CS domain before the handover, so the MGCF can issue the notification; other SIP messages, such as Info notification, can also be used to the handover control entity. The event);

8-9, the handover control entity detects the media channel negotiation completion event (such as receiving the media negotiation completion indication carried in the extended SIP signaling, or changing the media attribute of the receiving port of the second access leg to the ACTIVE according to the MGCF indication. Or Send Receive), forwarding a second access leg establishment request to the switching entity;

10-16. The switching entity performs media negotiation with the remote end according to the media information related to the handover carried in the second access leg. After the completion, the 200 ΟΚ response message is returned. After receiving the 200 OK response of the RelNVITE/UPDATE sent by the MGCF, the MGCF may instruct the MSC UE to perform the 10-channel transfer through the CS network signaling, and the MSC UE receives the 10 channels after receiving the response;

The switching entity releases the first access leg of the IMS domain (which may also be a terminal-initiated release, where the handover control entity in the network is released as an example). At this time, the MSC UE transfers the 10 channels of the media from the bearer connection controlled by the first access leg to the bearer connection controlled by the second access leg (the 10 channel switch can also detect the inband in the MSC UE) After the media channel negotiation is completed get on) ;

The foregoing embodiment can provide the user with a continuous service experience of the session, and the switching entity does not have to perform special processing for the multimedia session switched to the CS access, so as to ensure that the CS access-related features are shielded from other entities by the handover control entity, The switching entity switching processing function is consistent, and the logic of the switching processing is centralized; thereby facilitating the development and maintenance of device functions.

As shown in FIG. 17, a schematic structural diagram of a handover system according to an embodiment of the present invention includes: a handover control entity, configured to wait after receiving a setup request for a second access leg with a multimedia attribute initiated from a CS domain An indication of completion of the media channel negotiation corresponding to the second access leg; and sending a handover indication to the handover entity after receiving the indication that the media channel negotiation corresponding to the second access leg is completed; and the switching entity is configured to receive the handover control entity To the handover indication as a trigger condition, the media update is performed with the remote end to replace the second access leg with the first access leg.

The foregoing switching control entity includes: a receiving unit, configured to receive a setup request of a second access leg with a multimedia attribute initiated from a CS domain; and a holding unit, configured to keep the receiving unit receiving the second access leg Establishing a request, and waiting for the indication of the completion of the media channel negotiation corresponding to the second access leg, and sending the handover indication to the handover entity after receiving the indication of the completion of the media channel negotiation corresponding to the second access leg; the handover entity includes: And performing, by using the switching indication received by the holding unit as a trigger condition, performing media update with the remote end, so that the second access leg replaces the first access leg.

The foregoing switching system can provide a continuous service experience for the user, and the switching entity does not have to perform special processing for the multimedia session switched to the CS access, so as to ensure that the CS access-related features are shielded from other entities by the handover control entity, The switching entity switching processing function is consistent, and the logic of the switching processing is centralized; thereby facilitating the development and maintenance of device functions. The spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and modifications of the invention

Claims

Rights request

A method for implementing continuity of a multimedia call, comprising the steps of: after receiving a request for establishing a second access leg with a multimedia attribute initiated from a CS domain, the handover control entity waits for a second access leg An indication that the corresponding media channel negotiation is completed;

After receiving the indication that the media channel negotiation of the second access leg is completed, the handover control entity performs media update with the remote end to replace the second access leg with the first access leg.

2. The method according to claim 1, wherein the handover control entity determines that the received setup request of the second access leg is initiated from the CS domain according to one of the following manners:

The handover control entity determines according to the called number in the request;

The handover control entity determines according to the content of the access domain information in the request;

If the request does not carry the access domain information, the handover control entity determines that the request is initiated from the CS domain.

3. The method according to claim 1, wherein the handover control entity determines that the received setup request of the second access leg has a multimedia attribute according to at least one of the following manners: the handover control entity according to the request SDP information determination in ;

The handover control entity determines according to the bearer capability value of the UE initiating the request in the CS domain; the handover control entity determines according to the called number in the request.

The method according to claim 3, wherein the handover control entity obtains a bearer capability value of the UE initiating the request in the CS domain by:

The smart bearer in the CS domain triggers the bearer capability value of the UE in the CS domain to

In the IMS domain, the handover control entity obtains the load capacity value during the forwarding of the bearer capability value in the IMS domain.

The method according to claim 1, wherein the handover control entity includes the media negotiation process in the signaling channel before receiving the indication that the media channel negotiation of the second access leg is completed: The handover control entity receives the media negotiation request on the second access leg;

The handover control entity responds according to the remote media information saved in the first access leg establishment process.

The method according to claim 1, wherein after the negotiation of the media channel corresponding to the second access leg is completed, the MGCF sends a media channel negotiation completion indication corresponding to the second access leg to the handover control entity.

The method according to claim 6, wherein the MGCF sends an indication to the handover control entity that the media channel negotiation is completed by the second access leg, and the handover control entity learns the corresponding manner in the corresponding manner. The media channel negotiation completion event corresponding to the second access leg:

In a manner, the MGCF carries, in a message sent to the handover control entity, an indication that the media channel negotiation corresponding to the second access leg is completed; and the handover control entity obtains the indication from the message received on the second access leg, and according to the message The media channel negotiation completion event corresponding to the second access leg is obtained; mode 12, after detecting that the media channel negotiation corresponding to the second access leg is completed, the MGCF sets the media attribute in the SIP message from ACTIVE to ACTIVE, and switches to After the control entity sends the message from the second access leg, it detects that the media attribute in the message is ACTIVE, and then learns the media channel negotiation completion event corresponding to the second access leg.

The method according to claim 1, wherein after the negotiation of the media channel corresponding to the second access leg is completed, the MSC UE sends an indication to the handover control entity that the media channel negotiation corresponding to the second access leg is completed. .

The method according to claim 8, wherein the MSC UE sends an indication to the handover control entity that the media channel negotiation is completed by the second access leg, and the handover control entity learns the corresponding manner in the corresponding manner. The media channel negotiation completion event corresponding to the second access leg: the mode 21, the MSC UE carries, by using the first access leg, the indication that the media channel negotiation corresponding to the second access leg is completed in the message sent to the handover control entity; and the handover control Obtaining the indication from the message received by the entity on the first access leg, and obtaining the media pass corresponding to the second access leg The road negotiated the completion of the event.

10. The method of claim 1 wherein after the second access leg replaces the first access leg, further comprising releasing the first access leg.

11. The method of claim 10 wherein the first access leg is released by one of:

After detecting that the media channel negotiation is completed, the MSC UE initiates a release request on the first access leg, and the handover control entity receives the release request and confirms that the access leg is replaced with the remote end, and cooperates to release the first access. The corresponding resources of the leg;

After the handover control entity and the remote end complete the access leg replacement, the release request is initiated on the first access leg, and after receiving the release request, the MSC UE cooperates with releasing the corresponding resource of the first access leg.

The method according to claim 1, wherein the first access leg and the second access leg are respectively located on different terminals, or the first access leg and the second access leg are located in the same On the terminal.

The method according to claim 1, wherein the MSC UE converts the internal 10 channel of the MSC UE into 10 corresponding to the second access leg after the media channel negotiation corresponding to the second access leg is completed. aisle.

14. The method according to claim 1, wherein the MSC UE receives the handover control entity to perform 10-channel handover after the remote leg media update completion indication.

The method according to claim 1, wherein the media channel negotiation corresponding to the second access leg fails, and the UE that initiates the second access leg establishment request initiates a release request of the second access leg; and the network After receiving the release request of the second access leg, the second access leg is released and the first access leg is retained.

The method according to claim 1, wherein before the handover control entity receives the establishment request of the second access leg, the method further includes:

The user equipment detects the handover indication, and notifies the session indicated by the CS AF in USSD or SMS mode that the second access leg is to be upgraded in a upgrade manner; The user equipment sends an upgrade request to the CS network side, and after receiving the request from the CS network side, the MGCF converts the upgrade request into a media negotiation request in the IMS network, and sends the request to the CSAF;

The CSAF determines the received media negotiation request as an upgrade request according to the session identifier in the USSD or SMS, and converts the request into the establishment request of the second access leg, and sends the request to the handover control entity.

The user equipment detects the handover indication, and notifies the MGCF in the DTMF manner that the second access leg is to be upgraded in the session associated with the DTMF signal;

The user equipment sends an upgrade request to the CS network side, and the CS network side sends the upgrade request to the MGCF;

The MGCF assembles the information notified by the DTMF method and the information carried in the upgrade request to the establishment request of the second access leg, and sends the request to the handover control entity.

After the user equipment detects the handover indication, the second access leg is established in a upgrade manner on the session indicated by the notification switching control entity in the IMS network where the media to be switched is located;

The MGCF converts the upgrade request into a media negotiation request in the IMS network, and sends the request to the switching control entity;

The handover control entity determines, according to the session identifier in the notification received in the IMS network where the media to be switched is received, that the received media negotiation request is an upgrade request, and combines the notification information in the IMS network with the request as the first Two access leg establishment requests.

19. The method of claim 1 further comprising the step of: After the completion of the leg establishment, the timer is started, and the instruction for completing the media channel negotiation corresponding to the second access leg is waited for within the time limit.

20. A handover control entity, comprising:

a receiving unit, configured to receive a setup request of a second access leg with a multimedia attribute initiated from the CS domain;

a holding unit, configured to: keep the receiving unit receiving the establishment request of the second access leg, and wait for an indication that the media channel negotiation corresponding to the second access leg is completed;

And a switching unit, configured to perform, by the holding unit, an indication that the media channel negotiation corresponding to the second access leg is completed as a trigger condition, and perform media update with the remote end, so that the second access leg replaces the first access leg.

The entity according to claim 20, wherein the receiving unit includes: a first determining subunit, configured to determine, according to one of the following manners, that the received request for establishing the second access leg is from CS domain initiated:

If the request does not carry the access domain information, the first determining subunit determines that the request is initiated from the CS domain.

The entity according to claim 20, wherein the receiving unit comprises: a second determining subunit, configured to determine, according to one of the following manners, that the received request for establishing the second access leg has multimedia Attributes:

The entity according to claim 20, wherein the receiving unit includes: an identifying subunit, configured to determine, according to a session identifier in a notification received from an IMS network where the media to be switched is located, received The media negotiation request is an upgrade request and is combined with the IMS network. The notification information is the request to establish the second access leg.

24. The entity of claim 20, further comprising:

And a timing unit, configured to start a timer after determining that the second access leg is established, and instruct the holding unit to wait for an indication of that the media channel negotiation corresponding to the second access leg is completed within the timing time.

A multi-mode terminal supporting a multimedia call handover, comprising: a sensing unit, configured to perceive a completion event of a media channel negotiation corresponding to the second access leg; and a notification unit, configured to sense the second in the sensing unit After the completion event of the media channel negotiation corresponding to the access leg, an indication that the media channel negotiation corresponding to the second access leg is completed is issued.

The multimode terminal according to claim 25, further comprising: an initiating unit, configured to initiate, from the CS domain, a request for establishing a second access leg having a multimedia attribute.

The multimode terminal according to claim 25, further comprising: a first 10-channel conversion unit, configured to: after the sensing unit senses that the media channel corresponding to the second access leg is negotiated, The 10 channels between the die terminal and the user are converted from the media channel connection corresponding to the first access leg to the media channel corresponding to the second access leg.

The multimode terminal according to claim 25, further comprising: a second 10-channel conversion unit, configured to receive a 10-channel switch after the handover control entity receives the remote leg media update completion indication.

The multimode terminal according to claim 25, further comprising: a detecting unit, configured to detect a switching indication;

30. A media gateway control function entity, comprising: a sensing unit, configured to sense a completion event of the media channel negotiation corresponding to the second access leg, and a notification unit, configured to send the second access leg after the sensing unit perceives the completion event of the media channel negotiation corresponding to the second access leg The corresponding media channel negotiation completion indication.

The entity of claim 30, further comprising:

a conversion unit, configured to convert the upgrade request to be received after receiving the upgrade request from the CS network side

Media negotiation request in the IMS network.

32. The entity of claim 30, further comprising:

a receiving unit, configured to receive the information notified by the DTMF method and the upgrade request, and an assembling unit, configured to assemble the information notified by the DTMF manner and the information carried in the upgrade request into a request for establishing the second access leg.

33. A CS domain adaptation entity, comprising:

a second receiving unit, configured to receive a media negotiation request;

34. A system for implementing continuity of a multimedia call in a circuit domain, comprising: a multimode terminal supporting multimedia call handover, configured to initiate a request for establishing a second access leg having a multimedia attribute from a CS domain, and After the completion of the media channel negotiation completion event corresponding to the second access leg, the indication that the media channel negotiation corresponding to the second access leg is completed is sent;

35. A system for implementing continuity of a multimedia call in a circuit domain, comprising: a multimode terminal supporting multimedia call handover, configured to initiate a setup request for a second access leg having a multimedia attribute from a CS domain;

36. A switching system, comprising:

a handover control entity, configured to wait for an indication of completion of media channel negotiation corresponding to the second access leg after receiving the establishment request of the second access leg with the multimedia attribute initiated from the CS domain; and receiving the second connection Sending a handover indication to the handover entity after the indication of the completion of the media channel negotiation corresponding to the leg;

And a switching entity, configured to perform a media update with the remote end to receive the handover indication from the handover control entity, so that the second access leg replaces the first access leg.

The switching system according to claim 36, wherein the handover control entity comprises:

a holding unit, configured to: keep the receiving unit receiving the establishment request of the second access leg, and wait for the indication that the media channel negotiation corresponding to the second access leg is completed, and negotiate the media channel corresponding to the second access leg After the completed indication, a handover indication is sent to the handover entity.

The switching system according to claim 36 or 37, wherein the switching entity comprises:

And a switching unit, configured to perform a media update with the remote end by using the switching indication received by the holding unit as a trigger condition, so that the second access leg replaces the first access leg.