CN104254111A

CN104254111A - Processing method, equipment and system for reverse SRVCC (Single Radio Voice Call Continuity)

Info

Publication number: CN104254111A
Application number: CN201410508743.XA
Authority: CN
Inventors: 吴晓波; 徐小英; 刘海
Original assignee: Huawei Technologies Co Ltd
Current assignee: Godo Kaisha IP Bridge 1
Priority date: 2010-08-30
Filing date: 2010-08-30
Publication date: 2014-12-31
Anticipated expiration: 2030-08-30
Also published as: CN104254111B

Abstract

The invention provides a processing method, equipment and system for reverse SRVCC (Single Radio Voice Call Continuity). The method comprises the following steps: before UE (User Equipment) hands over voice service from a CS (Circuit Switched) domain network to a PS (Packet Switched) domain network, preconfiguring resource information needed for voice service handover in the PS domain network; in the process that the UE hands over voice service from the CS domain network to the PS domain network, establishing a forwarding channel between a first network element of a PS domain and a second network element of a CS domain by using the preconfigured resource information, wherein the forwarding channel is used for forwarding voice data between the UE and opposite UE after the UE is accessed to the PS domain network. The reverse SRVCC handover process of the embodiment of the invention does not need to wait for the completion of a domain handover process, thus the continuity of the voice service in reverse SRVCC handover is guaranteed to be good and the voice service after handover can also be guaranteed to obtain good voice service quality.

Description

Method, equipment and system for processing reverse single wireless voice call continuity

Technical Field

The embodiment of the invention relates to the technical field of communication, in particular to a method, equipment and a system for processing reverse single wireless voice call continuity.

Background

Second Generation (2nd Generation, 2G) or third Generation (3rd Generation, 3G) networks have been deployed for many years to form a full coverage situation. Meanwhile, with the development of network technology, some pure PS domain networks that only provide Packet Switching (PS), such as Long Term Evolution (LTE) networks, have gradually covered some urban areas and traffic hot spots at the initial stage of network establishment. Thus, in current communication networks, these pure PS domain networks and 2G/3G networks are in a state of coexistence.

Voice traffic has different bearer mechanisms corresponding to different communication networks. Specifically, in a 2G/3G network, a voice call supports a conversational Service carried by a Circuit Service (CS); in the PS domain network, the Voice call supports a Packet Switched (PS) domain-carried session service, also called Voice Over Internet Protocol (VOIP) service, and an IP Multimedia Subsystem (IP Multimedia Subsystem, IMS for short) provides service quality assurance.

Compared with the CS domain network, the PS domain network can provide a higher-speed and higher-quality voice service for the user, and can meet more data service requirements of the user, so in order to cultivate more voice users of the PS domain network, an operator usually sets the priority level of the PS domain higher than that of the CS domain, so that the voice users preferentially camp in the PS domain network. Therefore, under the situation that a CS domain network and a PS domain network coexist, when a User Equipment (User Equipment, abbreviated as UE) has initiated a Voice call in a CS domain of a 2G or 3G network and moves to an area simultaneously covered by the PS domain network, based on a requirement for higher Voice service quality or considering a limitation of high priority, the UE needs to convert the Voice call from the CS domain to the PS domain of the LTE/HSPA network, i.e., perform a processing flow of reverse Single Radio Voice Call Continuity (SRVCC). During the handover, the voice interruption delay caused by the handover cannot exceed 300ms for the voice call, otherwise the user experience is poor.

The existing reverse SRVCC process is generally implemented by the following two schemes. The first scheme is that when the UE performs the reverse SRVCC process, the voice service is first exited from the 2G/3G CS domain network, and then re-accessed to the LTE network, and a process flow of domain switching is initiated. In the scheme, for the access process of the network, the speed of the UE to re-access the voice service to the LTE network is fast, and a large voice interruption delay is not generated, and the experience of the voice continuity of the user is not sufficiently affected, but for domain switching, the UE has different time values according to different application scenarios, and the shortest required time is far longer than the minimum 300ms required by the voice handover interruption delay, so that the voice continuity during the reverse SRVCC handover is seriously affected, and the service quality is poor.

The second reverse SRVCC processing scheme is that when the UE performs the reverse SRVCC processing, the bearer of the voice service is first switched from the CS domain to the PS domain in the 2G/3G network, that is, the domain switching is first performed in the 2G/3G network, and then the LTE network is accessed, so as to completely switch the voice service to the PS domain of the LTE network. In the scheme, although the service continuity of the voice service of the UE between the LTE PS domain network and the 2G/3G CS domain network can be maintained through the transition of the PS domain voice service of the 2G/3G network, the PS domain voice service supported by the 2G/3G PS network can only provide poor service quality for the UE, so that a user cannot obtain good voice service for a long time.

Disclosure of Invention

The embodiment of the invention provides a method, equipment and a system for processing reverse single wireless voice call continuity, which are used for solving the defect that the existing reverse SRVCC technology cannot ensure good voice continuity due to overlarge voice switching interruption time delay or has poor service quality in a voice switching process.

To achieve the above object, an embodiment of the present invention provides a method for processing reverse single wireless voice call continuity, including:

the method comprises the steps that before a user terminal switches a voice service from a circuit domain network to a packet switching domain network, resource information required by voice service switching is pre-configured in the packet switching domain network;

and in the process that the user terminal switches the voice service from the circuit domain network to the packet switching domain network, establishing a forwarding channel between a first network element of the packet switching domain and a second network element of the circuit domain by using the pre-configured resource information, wherein the forwarding channel is used for forwarding the voice service data between the user terminal and an opposite terminal user terminal after the user terminal is accessed to the packet switching domain network.

In order to achieve the above object, an embodiment of the present invention further provides a user terminal, including:

a resource information configuration module, configured to, before the user terminal switches the voice service from the circuit switched domain network to the packet switched domain network, pre-configure resource information required for voice service switching in the packet switched domain network, so that, in a process in which the user terminal switches the voice service from the circuit switched domain network to the packet switched domain network, a forwarding channel can be established between a first network element of the packet switched domain network and a second network element of the circuit switched domain network by using the pre-configured resource information, where the forwarding channel is used to forward voice service data of the user terminal and an opposite-end user terminal after the user terminal is accessed to the packet switched domain network.

In order to achieve the above object, an embodiment of the present invention further provides a mobility management entity, including:

a receiving module, configured to receive a handover request, where the handover request is used to request that a voice service of a user equipment is handed over from a circuit switched domain network to a packet switched domain network;

and a forwarding channel establishing module, configured to, according to the switching request, control, by using resource information required for voice service switching, which is configured in the packet switched domain network in advance by the user terminal, to establish a forwarding channel between a first network element of the packet switched domain network and a second network element of the circuit switched domain network in a process in which the user terminal switches a voice service from the circuit switched domain network to the packet switched domain network, where the forwarding channel is used to forward voice service data between the user terminal and an opposite-end user terminal after the user terminal is accessed to the packet switched domain network.

To achieve the above object, an embodiment of the present invention provides a system for processing reverse single wireless voice call continuity, including: the system comprises a user terminal, a first network element and a second network element; wherein,

the user terminal is used for presetting configuration resource information required by voice service switching in the packet switched domain network before switching the voice service from the circuit domain network to the packet switched domain network;

the first network element is located in a packet switched domain network, the second network element is located in a circuit domain network, a forwarding channel can be established between the first network element of the packet switched domain and the second network element of the circuit domain by using the pre-configured resource information in the process that the user terminal switches the voice service from the circuit domain network to the packet switched domain network, and the forwarding channel is used for forwarding the voice service data between the user terminal and an opposite terminal user terminal after the user terminal is accessed to the packet switched domain network.

The processing method, the equipment and the system for the continuity of the reverse single wireless voice call of the embodiment of the invention configure the bearing resource information required by the voice switching in the PS domain network in advance by the UE before the UE switches the voice service from the CS domain network to the PS domain network, and establish the forwarding channel between the CS domain network and the PS network of the voice data by utilizing the reserved bearing information which is allocated for the UE in advance by the PS domain network in the process of switching the voice service from the CS domain network to the PS domain network by the UE, thereby ensuring that the UE can quickly transmit the voice data with an opposite terminal through the established forwarding channel after the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and quickly accesses to the PS domain network without waiting for the completion of a domain switching process for a long time, and ensuring the good voice service continuity in the reverse SRVCC switching process, furthermore, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Drawings

Fig. 1 is a flowchart of a reverse single wireless voice call continuity processing method according to a first embodiment of the present invention;

FIG. 2 is a flowchart of a second embodiment of a method for reverse single wireless voice call continuity handling according to the present invention;

fig. 3 is a signaling diagram illustrating an IMS registration and an SIP session establishment procedure performed in a PS domain before a user equipment initiates a reverse SRVCC handover in the method for processing reverse single wireless voice call continuity according to an embodiment of the present invention;

fig. 4 is a flowchart of a third embodiment of a reverse single wireless voice call continuity processing method according to the present invention;

FIG. 5 is a signaling diagram illustrating a domain switching procedure in the method for processing reverse single wireless voice call continuity according to an embodiment of the present invention;

fig. 6 is a signaling diagram of a fourth embodiment of a method for processing reverse single wireless voice call continuity according to the present invention;

fig. 7 is a signaling diagram of a fifth embodiment of a processing method for reverse single wireless voice call continuity according to the present invention;

fig. 8 is another signaling diagram illustrating the MS registration and the SIP session establishment procedure performed by the ue in the PS domain before initiating the reverse SRVCC handover in the processing method for reverse single wireless voice call continuity according to the embodiment of the present invention;

fig. 9 is a signaling diagram of a sixth embodiment of a method for processing reverse single wireless voice call continuity according to the present invention;

fig. 10 is a schematic structural diagram of a first embodiment of a user terminal according to the present invention;

fig. 11 is a schematic structural diagram of a second embodiment of a user terminal according to the present invention;

fig. 12 is a schematic structural diagram of a first embodiment of a mobility management entity device according to the present invention;

fig. 13 is a schematic structural diagram of a second embodiment of a mobility management entity device according to the present invention;

fig. 14 is a block diagram of an embodiment of a reverse single wireless voice call continuity processing system according to the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a flowchart of a first embodiment of a method for processing reverse single wireless voice call continuity according to an embodiment of the present invention, as shown in fig. 1, the method includes the following steps:

step 100, before the UE switches the voice service from the CS domain network to the PS domain network, pre-configuring resource information required for the voice service switching in the PS domain network;

in the reverse SRVCC processing scheme of the embodiment of the present invention, before the UE initiates the handover of the voice service from the CS domain network to the PS domain network, in order to configure in advance resource information capable of carrying the voice service to the PS domain network in the PS domain network, so that after the reverse SRVCC handover process is formally initiated, a core network element in the PS domain network can quickly establish a new voice carrying path with the opposite terminal for the UE by using the pre-allocated carrying resource, and before the UE has not initiated the handover of the voice service, the UE completes in advance the PS domain network configuration at the user media level in the core network element of the PS domain network, thereby configuring in advance certain resource information for transmitting the voice data packet in the PS domain network.

Specifically, the preparation process occurs before the UE initiates the reverse SRVCC handover of the voice service, and the UE completes the configuration of the user media plane in the PS domain network, such as the LTE network, in advance, so that the core network element of the PS domain network can allocate necessary resource information for bearing the VOIP voice service in the PS domain network to the UE in advance, for example, resource information such as address, number, codec, and the like required by the UE for bearing the voice service in the PS domain network, and thus when the UE actually initiates the domain handover of the voice service, the control network element can quickly establish a new voice bearer channel between the UE and the opposite terminal by using the pre-allocated resource information, thereby ensuring the continuity of the voice service of the UE in the handover process.

Step 101, in a process of initiating a handover of a voice service from a CS domain network to a PS domain network by a UE, establishing a forwarding channel between a first network element of the CS domain network and a second network element of the PS domain network by using pre-configured resource information, where the forwarding channel is used to forward voice service data of the UE after the UE is accessed to the PS domain network.

In the process that the UE really initiates the handover of the voice service from the CS domain to the PS domain, because the PS domain network has allocated resource information, which can be used to carry the relevant service of the UE in the PS domain network, to the UE in advance before the UE performs the reverse SRVCC handover, the PS domain network can quickly establish a new data forwarding channel for the UE to perform voice data interaction with the peer terminal by using the pre-configured resource information in the handover process.

Specifically, in order to eliminate the influence of too long time required for domain switching on the interruption delay of the voice switching service in the reverse SRVCC process, and to quickly establish a voice data forwarding channel between the UE and the opposite terminal, in the embodiment of the present invention, after the UE initiates the reverse SRVCC service switching process, a first network element in the CS domain network and a second network element in the PS domain network will establish forwarding channels with each other by using the reserved resource information that is allocated to the UE in advance by the PS domain network in the advance registration process of the UE. The forwarding channel is used for forwarding voice data interacted between the UE and the UE at the opposite end after the UE is accessed to the PS domain network, specifically after the UE is accessed to an Evolved NodeB (ENB) of the PS domain network, and before the UE performs a domain switching procedure, which is equivalent to providing a new path for performing a voice session between the UE and the UE at the opposite end.

Because the PS domain network has already allocated resource information for the UE to carry the service of the UE in the PS domain in advance, based on the preconfigured resource information, the forwarding channel between the first network element and the second network element can be established quickly without depending on the completion of the domain switching procedure of the UE in the reverse SRVCC handover process. Meanwhile, for the UE, in the handover process of the reverse SRVCC, the UE can also quickly complete the access operation in the PS domain network to access to the ENB of the PS domain network, so in the embodiment of the present invention, after the UE initiates the reverse SRVCC handover for the voice service, once the UE successfully accesses to the PS domain network, the UE can immediately perform voice data interaction with the opposite UE through the forwarding channel without waiting for the completion of the domain switching procedure for a long time. Therefore, the MME can quickly switch the voice service of the UE to the VOIP bearer of the PS domain network in a short time under the PS domain network environment, quickly establish voice communication with the opposite terminal, and cannot influence the voice switching interruption time delay of the reverse SRVCC in the embodiment of the invention even if the time required for completing the domain switching is too long, thereby ensuring the good voice continuity of the voice service in the switching process.

Furthermore, because the established new forwarding channel acts on the basis that the UE completes the PS domain network access, the voice service of the UE based on the forwarding channel belongs to the VOIP voice service type of the PS network, and compared with the PS domain voice service transition scheme of the 2G/3G network in the prior art, the forwarding channel can also ensure that the voice service of the UE obtains good service quality in the switching process.

In the method for processing the reverse single wireless voice call continuity service of this embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs configuration of bearer resource information required for completing the voice service switching in the PS domain network in advance, and in the process of switching the voice service from the CS domain network to the PS domain network, the PS domain network is used to pre-allocate the bearer information allocated to the UE in advance, so as to establish a forwarding channel between the CS domain network and the PS network for voice data, so that after the UE truly initiates the switching of the voice service from the CS domain network to the PS domain network and rapidly accesses to the PS domain network, the UE can rapidly transmit the voice data with the opposite terminal through the established forwarding channel without waiting for completion of a long-term domain switching flow, thereby ensuring good voice service continuity performance in the reverse vcc switching process, furthermore, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 2 is a flowchart of a second embodiment of a processing method for reverse single wireless voice call continuity according to the present invention, as shown in fig. 2, the method includes the following steps:

step 200, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs IMS registration and establishes a Session Initiation Protocol (SIP) Session in the PS domain network, so as to pre-configure resource information in the PS domain network;

in this embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the resource information configuration process performed in the PS domain network in advance may be specifically implemented by an IMS registration and an SIP session establishment procedure performed in the PS domain network in advance by the UE, and specifically, the resource information configuration process may specifically include the following sub-steps:

step 2000, the UE initiates an attach procedure and a main Packet Data Protocol (PDP) activation procedure on a Serving GPRS Support Node (SGSN) of the PS domain network;

before the UE switches the voice service from the CS domain network to the PS domain network, the UE may complete registration in the PS domain network in advance according to a registration procedure specified by a protocol. Specifically, the UE may initiate and complete an Attach (Attach) procedure and a primary PDP activation procedure to the SGSN device of the PS domain network in sequence according to the procedures specified by the protocol. Through the attach and primary PDP activation procedure, the UE may negotiate with the SGSN about information required for the UE to initiate a Voice Call in the PS domain network, such as Voice CodeC type (CodeC) information of the UE in the PS domain network and session transfer Number (STN-SR) information for SRVCC, and cause the PS domain network side to allocate required resources to the UE. Specifically, for the CodeC information, in an attach procedure initiated by the UE, the UE may carry, in an attach request sent to the SGSN, the CodeC information supported by default in the PS domain network, so that based on the CodeC information, the SGSN may know a corresponding CodeC type of the UE in the PS domain.

Optionally, after the primary PDP activation procedure, the UE may also initiate a secondary PDP activation procedure to the SGSN, where the secondary PDP activation procedure assists the primary PDP activation procedure, and in the secondary PDP activation procedure, the UE may indicate to the SGSN the service level of the UE for this PS domain network registration, for example, indicating that this registration procedure is specifically used for voice services.

Step 2001, the UE initiates an SIP session establishment procedure to a service centralization and Continuity Application Server (SCC AS for short) of the PS domain network;

after the UE completes registration of the PS domain on the SGSN, further, the UE may also initiate a SIP session establishment request to the SCC AS, and establish a reserved SIP session connection in the PS domain network in advance by initiating a SIP session establishment procedure with the SCC AS. Specifically, the purpose of the SIP session establishment request initiated by the UE is not really to establish a SIP session with the opposite UE, and in fact, the pre-established SIP session connection may not play any substantial role before the UE does not initiate a handover of voice traffic from the CS domain network to the PS domain network, which may simply allocate corresponding resources for the UE in the core network of the PS domain network without any data transmission, and even during the SIP session establishment, the SCC AS does not need to make a real call to the opposite UE. However, once the UE initiates the reverse SRVCC handover procedure of the voice service, in the reverse SRVCC handover procedure, the UE can quickly switch the voice service to the VOIP voice of the PS domain based on the pre-allocated resources, and perform the subsequent domain switching procedure of the voice service, so that it is not necessary to temporarily initiate the SIP session in the subsequent domain switching procedure, which is equivalent to accelerating the speed of the subsequent domain switching procedure.

Specifically, the UE may carry special reverse SRVCC indication information in the SIP session establishment request sent to the SCC AS, where the reverse SRVCC indication information is used to indicate that the SIP session established by the SCC AS at this time is used in a subsequent reverse SRVCC handover procedure, so AS to indicate that the SCC AS does not need to initiate a real call to the opposite-end UE when establishing the SIP session for the UE according to the SIP session establishment request. Further, in the embodiment of the present invention, since the SIP session that is established in the PS domain network by the UE in advance and the pre-configured resource information are not transmitted substantially before the UE performs the reverse SRVCC handover, for any voice bearer path, if there is no packet transfer for a long time, the corresponding core network element may release the resource information belonging to the bearer according to the specification of the protocol layer. Therefore, in the embodiment of the present invention, in order to avoid such a situation, the reverse SRVCC indication information carried in the SIP session establishment request sent by the UE to the SCC AS may also be used to indicate that the SCC AS does not actively trigger the release procedure of the resource information of the UE even if there is no data transmission on the reserved SIP session connection for a long time.

In practical application, the UE carrying the reverse SRVCC indication information in the SIP session establishment request sent to the SCC AS may be specifically implemented in the following two ways: the UE may separately carry an indication information, such AS an rSRVCC indication information, in the SIP session establishment request, where the rSRVCC indication information indicates that the SCC AS is substantially used for the establishment of the SIP session in the subsequent reverse SRVCC handover; or, the UE may also carry a special called number in the SIP session establishment request sent to the SCC AS, where the special called number may be a specific number used for reverse SRVCC handover, and when the SCC AS receives the SIP session establishment request carrying a similar called number, the SCC AS may also know that the SIP session is used for reverse SRVCC handover, so that only the UE may negotiate allocation of bearer resource information during the SIP session establishment process, and the UE may not actually initiate a voice call to the UE at the opposite end.

Further optionally, in the process that the UE performs IMS registration in the PS domain network and establishes SIP session connection in the PS domain network, the UE may send another indication information to the SGSN in addition to the reverse SRVCC indication information to the SCC AS. The indication information is used to indicate that the SGSN does not initiate a Radio Access Bearer (RAB) establishment procedure after the SIP session of the UE in the PS domain network is established. The reason why the UE sends the indication information to instruct the SGSN not to initiate the RAB establishment procedure is that: since the substantial role of establishing the SIP session connection for the UE before the reverse SRVCC handover is to prepare for the subsequent reverse SRVCC handover procedure, and no transmission of any voice data of the UE is performed on the SIP session connection before the reverse SRVCC handover procedure is performed, the SGSN also does not need to initiate a substantial RAB establishment procedure, thereby avoiding waste of resources.

Specifically, the UE may send the indication information to the SGSN in the following several methods. If the SGSN supports the Gn/Gp mode, the UE may set a corresponding flag, for example, set a Maximum Bit Rate (MBR) field to 0, to inform the SGSN not to initiate an RAB establishment procedure, by sending a primary PDP activation request to the SGSN in the primary PDP activation procedure of step 2000; secondly, the UE can also carry indication information in the primary PDP activation request sent to the SGSN to indicate the SGSN that the VOIP voice bearer is reserved for reverse SRVCC, thereby indicating the SGSN not to initiate RAB establishment process; thirdly, the UE may not add any special indication, and after the SGSN receives the primary PDP activation request sent by the UE, if the network does not support the capability of establishing the PS domain voice service, the SGSN may not trigger the RAB establishment procedure. If the SGSN supports the mode of S4, the UE may set a Traffic Class parameter with a Service Class as a session Class in a Quality of Service (QoS) parameter carried in a primary PDP activation request sent to the SGSN, so as to inform the SGSN that an RAB establishment procedure is not required to be triggered.

It should be noted that, if the UE does not report the CodeC information supported in the PS domain network to the SGSN in the attach procedure to the SGSN, optionally, in the signaling interaction process of SIP session establishment between the UE and the SCC AS in this step, the UE may also negotiate the CodeC information of the UE in the PS domain network with the SCC AS, and after the negotiation is successful, the SCC AS carries the negotiated CodeC information in the SIP response message and returns the information to the UE. In addition, information such AS a destination address used for identifying service transmission of the UE in the PS domain network may also be negotiated by the UE and the SCC AS during the signaling interaction, and the SCC AS carries the negotiated address information in the SIP response message, and returns the address information to the UE in cooperation with the CodeC information. Through the registration process of the UE in the PS domain network in this step 200, the PS domain network pre-allocates the reserved resource information for the UE to transmit the voice data in the PS domain network. Specifically, the reserved resource information includes, in addition to information such as STN-SR number, address, CodeC, or the like of the UE in the PS domain Network, the reserved resource information at least should include first information allocated to the UE for the reverse SRVCC handover, where the first information is a first Network element in the PS domain Network, such as an Access Transfer Gateway (ATGW) or a Packet Data Network Gateway (PGW).

The first information may specifically include information such as an address and/or a port allocated by the first network element to the UE, and based on the first information, other network elements in the network can identify the first network element, so as to establish a data forwarding channel with the first network element. It should be noted that the port information pre-allocated by the first network element referred to herein may specifically be information of a port, which is pre-reserved for the reverse SRVCC handover, in the first network element, that is, the first network element may pre-designate a specific port for use in the reverse SRVCC handover process, so that when the first network element allocates the first information to the UE, the first network element does not need to temporarily allocate the port to the UE, but may allocate the information of the pre-designated port to the UE. It should also be noted that, in practical applications, the ATGW is generally integrated with a domain Transfer Control function (ATCF), so in the embodiment of the present invention, when the first network element is referred to as an ATGW in the following description, the first network element is replaced by the ATCF/ATGW, and signaling messages sent to the ATGW by other network elements may be forwarded to the ATGW through the ATCF.

Specifically, if the first network element is a PGW, the UE may instruct the SGSN to obtain the first information from the PGW in the primary PDP activation procedure initiated to the SGSN in step 2000; or, if the UE further sends a secondary PDP activation request to the SGSN after initiating the primary PDP activation procedure to the SGSN, the UE may further instruct the SGSN to acquire the first information from the PGW in the secondary PDP activation procedure. If the first network element is an ATCF/ATGW, the UE may anchor IMS registration to the ATCF device in the IMS registration process in the PS domain, and anchor a user plane of the SIP session to the ATGW in the SIP session establishment process with the SCC AS, so that the ATCF/ATGW allocates corresponding bearer resource information, that is, allocates the first information, to the UE in the PS domain network.

In the embodiment of the present invention, it should be further noted that, after the UE completes IMS registration in the PS domain and initiates establishment of an SIP session to the SCC AS, in order to further reduce a handover delay caused by the UE in a reverse SRVCC handover process, optionally, the UE may also pre-establish a reserved VOIP voice bearer for carrying the VOIP voice service of the UE between the UE and the SCC AS in the PS domain network on the basis thereof, that is, further allocate bearer information for the VOIP voice service to the UE in a core network element of the PS domain network. The pre-established reserved VOIP voice bearer is also used in the subsequent reverse SRVCC switching process and is in a suspended state before switching, and the UE does not need to temporarily establish the VOIP voice bearer in the process of really initiating the reverse SRVCC switching by pre-establishing the suspended VOIP voice bearer, thereby further accelerating the speed of switching the voice service to the PS domain network.

It should be noted that, in addition to establishing the reserved VOIP voice bearer for the UE after the SIP session connection between the UE and the SCC AS is established and before the reverse SRVCC handover procedure, in the embodiment of the present invention, if the first network element of the bearer network in the PS domain is the ATCF/ATGW, the establishment procedure of the VOIP voice bearer may also be triggered by the core network element in the PS domain network after the UE initiates the reverse SRVCC handover request and during the reverse SRVCC handover procedure. Specifically, the triggering of the VOIP voice bearer establishment procedure may be triggered by an SGSN, a Mobile Switching Center (MSC), an ATCF or other core network element in the PS domain network immediately after the UE initiates the reverse SRVCC handover request. Compared with the scheme for establishing the reserved VOIP voice bearer before the reverse SRVCC switching process, the scheme establishes the VOIP voice bearer only in the reverse SRVCC switching process, but avoids the situation that related voice resources need to be reserved in the PS domain network before the reverse SRVCC switching process does not occur, thereby avoiding the waste of resources in the PS domain network.

It should be noted that, for voice services, the UE may be classified into two types, i.e., supporting Dual Transfer Mode (DTM) or Universal Mobile Telecommunications System (UMTS), and not supporting DTM Mode or UMTS Mode. If the UE supports the DTM or UMTS mode, the voice service and the data service of the UE can be simultaneously and respectively borne on two different types of the CS domain and the PS domain, therefore, before the UE carries out reverse SRVCC switching, the UE can carry out IMS registration of the PS domain network after establishing a voice conversation of the CS domain with the opposite terminal UE, and a new IMS registration flow can not influence the voice service of the UE in the original CS domain network; if the UE does not support DTM or UMTS mode, the voice service and data service of the UE can not be simultaneously loaded on two different types of CS domain and PS domain, therefore before the UE performs reverse SRVCC switching, the IMS registration and SIP session establishment of the UE in the PS domain network must be completed before the UE establishes the voice session of the CS domain in the CS domain network, namely, the required resources are firstly distributed for the UE in the PS domain network, then the UE establishes a normal voice session in the CS domain network, and loads the voice service in the CS domain network, thereby avoiding the condition that the registration of IMS registration and SIP session affects the voice service in the original CS domain network.

Step 201, UE initiates the switching of voice service from CS domain network to PS domain network;

step 202, establishing a forwarding channel between a first network element of the PS domain and a second network element of the CS domain by using pre-configured resource information;

step 203, the UE is accessed to the PS domain network;

after the UE completes the IMS registration and SIP session establishment process in the PS domain network and the PS domain network allocates the resource information required for bearing and transmitting voice data to the UE in advance before switching, in the process that the UE really switches the voice service from the CS domain network to the PS domain network, the UE can smoothly establish a forwarding channel with each other by using the resource information allocated in advance by the PS domain network and the pre-established SIP session, the first network element of the PS domain and the second network element of the CS domain on the premise that the UE does not perform domain switching or the domain switching process is not completed. Therefore, when the ENB in the PS domain network allocates the access switching resource for the UE according to the switching request and the UE is smoothly accessed into the PS domain network, the forwarding channel between the first network element and the second network element can be used for carrying and transmitting the voice data between the UE and the opposite-end UE after the UE is accessed into the PS domain network and before the domain conversion operation is not carried out or the domain conversion process is not completed.

Specifically, the second network element of the CS domain network may be an MSC (hereinafter referred to as an rSRVCC MSC) for supporting an SRVCC service, downlink voice data sent by the UE to the peer UE may be transmitted to the peer UE through the UE, the ENB, the first network element, a forwarding channel between the first network element and the second network element, and through the second network element, and uplink voice data sent by the peer UE to the UE may be transmitted to the UE through an opposite path, so that the UE can also perform voice data transmission with the peer UE through the newly established forwarding channel on the premise of not depending on a domain switching procedure, thereby ensuring good continuity of a voice call in a handover process.

Specifically, in the process of reverse SRVCC handover, the establishment of the forwarding channel between the first network element and the second network element may be controlled by a Mobility Management Entity (MME). For example, if the first network element of the PS domain network is a PGW, in the embodiment of the present invention, a specific process of controlling, by the MME, establishment of a forwarding channel between the first network element of the PS domain and the second network element of the CS domain by using pre-configured resource information may be as follows:

in the pre-registration process of the UE, the first information such as the address and/or the port allocated to the UE by the first network element is acquired and stored by the SGSN, so that the MME can acquire the first information from the SGSN in the reverse SRVCC handover process at this time; further, in order to enable a second network element in the CS domain network to establish a forwarding channel with the first network element for transmitting the voice data, the MME further forwards the obtained first information to the second network element, which is equivalent to inform the second network element of information such as an address and/or a port of the first network element, so that when the second network element receives uplink voice data sent by the peer UE to the UE, the uplink voice data can be transmitted to the first network element according to the information, so as to transmit the uplink voice data to the UE.

Further, in order to enable the first network element to also obtain information such as an address and/or a port of the second network element, so that when the first network element receives downlink voice data sent to the opposite terminal by the UE, the downlink voice data can be transmitted to the corresponding second network element according to the obtained related information of the second network element, and then transmitted to the opposite terminal UE, the MME further obtains second information allocated to the forwarding channel by the rsrvcmsc from the second network element of the CS domain, that is, the rSRVCC MSC. Likewise, the second information includes information such as the address and/or port allocated to the UE by the rSRVCC MSC. After acquiring the second information from the second network element, the MME forwards the second information to the first network element, so that if the first network element receives downlink voice data sent by the UE to the opposite-end UE, the first network element can also transmit the downlink voice data to the second network element according to the address and/or port information of the second network element.

It should be noted that, while the MME forwards the address and/or port information allocated by the first network element to the second network element, the MME may also forward context information registered by the UE in the registration process to the second network element, for example, CodeC information corresponding to the UE in the PS domain network and STN-SR information, so that the rSRVCC MSC of the second network element can perform corresponding coding operation on the received uplink voice data sent by the UE at the opposite end according to the CodeC information, perform corresponding coding operation on the downlink voice data sent by the UE, and perform transmission between the UE and the UE at the opposite end.

If the first network element in the PS domain network is the ATCF/ATGW, in the embodiment of the present invention, the process of the MME controlling the establishment of the forwarding channel between the ATCF/ATGW and the rSRVCC MSC by using the pre-configured resource information may be the following process: after receiving the handover request forwarded by the rSRVCC MSC, the MME may first obtain, from the SGSN device, STN-SR information that the UE has registered in the PS domain network in advance, and forward the STN-SR information to a second network element in the CS domain network, that is, to the rSRVCC MSC; after learning STN-SR information registered by UE in PS domain network, rSRVCC MSC can accurately address ATCF equipment anchoring the registration request in the pre-registration process of UE, so that second information of address and/or port of allocated IP is sent to a first network element user plane entity ATGW in PS domain network through the ATCF equipment; and then the first network element user plane entity ATGW can also accurately send the first information of the address and/or the port which is allocated for the UE in advance to the rSRVCC MSC after knowing the address and/or the port information of the rSRVCC MSC. Therefore, after the first network element and the second network element mutually exchange the address and/or the port information of each other, the forwarding channel between the first network element and the second network element is also successfully established.

It should be noted that, in the above process, if the UE is of a type supporting a DTM or UTMS mode, the step of acquiring, by the MME, STN-SR information that the UE is registered in the PS domain network in advance from the SGSN device may be implemented by the SGSN receiving the handover request and actively sending the STN-SR information together to the MME in the handover request forwarded to the MME; if the UE is of a type that does not support the DTM or UTMS mode, the SGSN does not receive the handover request, so that the step of acquiring, by the MME from the SGSN device, the STN-SR information that the UE has registered in the PS domain network in advance may be implemented by the MME sending an identifier query request, for example, sending a location update request message, to the HSS to query, according to the identifier of the UE, the SGSN corresponding to the UE in the HSS, and then acquiring, to the SGSN, the context information that the UE has registered in advance, where the context information includes the STN-SR information.

It should be further noted that, if the first network element in the PS domain network is the ATCF/ATGW, in the embodiment of the present invention, the process of establishing the forwarding channel between the ATCF/ATGW and the rSRVCC MSC may also be executed without being controlled by the MME, specifically, the process is as follows: after receiving the handover request, the rSRVCC MSC may also directly send an identifier query request carrying the UE identifier, for example, a location update request message, to the HSS to query the identifier of the SGSN corresponding to the UE; and after inquiring the label of SGSN, rSRVCC MSC can directly forward the switching request to the appointed SGSN, and obtains the context information registered in advance by UE from SGSN through the switching request, so that SGSN can further forward the switching request to MME to trigger the preparation process of target side bearing, meanwhile, rSRVCC MSC can directly address ATCF equipment anchoring the registration request in the pre-registration process of UE according to the obtained STN-SR information of UE, thereby establishing a forwarding channel between ATCF equipment and first network element ATGW.

As can be seen from the above description, in the process of the reverse SRVCC handover of the UE, the process of establishing the forwarding channel between the first network element and the second network element may be performed in various ways, and in the following embodiments, various implementation manners will be described in detail respectively.

It should be further noted that, in the embodiment of the present invention, in the process of the reverse SRVCC handover of the UE, the process of establishing the forwarding path between the first network element and the second network element in the process domain where the UE accesses the PS domain network may be performed in a cross manner at the same time. Specifically, the ENB of the PS domain network may allocate access resources to the UE during the establishment of the forwarding channel, and since the processing speed of the UE on the network access procedure is usually fast, the UE can usually successfully access the PS domain network before the forwarding channel is established. Therefore, once the forwarding channel is established, the UE can perform voice data communication with the UE at the opposite end through the ENB of the PS domain network, the first network element, the forwarding channel between the first network element and the second network element, and the communication link of the second network element, which is equivalent to completing the handover in the PS domain network. And the establishment process of the forwarding channel only needs a short time compared with the domain switching process, so in the embodiment of the invention, the UE can quickly switch the voice service to the PS domain network, and the completion of the switching does not depend on the domain switching process, thereby ensuring the good voice service continuity performance in the reverse SRVCC switching process.

For the opposite UE, it should be noted that, at this time, although the UE has already been accessed to the PS domain network and also has already loaded its own voice service to the PS domain network, since the opposite UE still performs voice data interaction with the UE through the second network element of the CS domain, that is, through the MGW, for the opposite UE, it cannot know the fact that the UE has switched the voice service to the PS domain network, and still considers that the UE still performs voice data communication with the UE in the CS domain network, but this does not affect the service quality of the voice service between the two, and does not bring any other adverse problem.

Step 204, UE initiates a domain switching process;

step 205, after the domain switching process is completed, the SCC AS controls to release the resources occupied by the forwarding channel.

After the forwarding channel is established and the UE can perform voice data communication with the peer UE by using the forwarding channel and the pre-established reserved VOIP voice bearer, in the embodiment of the present invention, in order to truly switch the voice service between the UE and the peer UE to the PS domain network, optionally, the UE may also initiate a domain switching procedure on the basis. The domain switching process is performed on the basis that the UE can perform normal VOIP voice service with the opposite-end UE, so that the interruption of the voice service of the UE is not caused due to the high speed and the low speed of the domain switching process.

After the domain switching process is completed, the UE does not need to transmit downlink voice data to the UE at the opposite end through a forwarding channel between the first network element and the second network element, and also does not need to receive uplink voice data sent by the UE at the opposite end through the forwarding channel, but can directly perform voice data communication with the UE at the opposite end through a communication link of the ENB, a Serving Gateway (Serving GW for short), and a PGW, so that the SCC AS can control to release resources occupied by the forwarding channel at this time, so AS to really complete the reverse SRVCC handover process.

In the method for processing the continuity of a reverse single wireless voice call of the embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs IMS registration in the PS domain network in advance and initiates establishment of an SIP session, so that the PS domain network allocates bearer resource information to the UE in advance, and in the process of switching the voice service from the CS domain network to the PS domain network, the PS domain network allocates the reserved bearer information to the UE in advance, and establishes a forwarding channel between the CS domain network and the PS network for voice data, so that after the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and rapidly accesses to the PS domain network, the UE can rapidly transmit voice data with an opposite terminal through the established forwarding channel without waiting for completion of a long-time domain switching flow, thereby ensuring good voice service continuity in the reverse SRVCC switching process, furthermore, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 3 is a signaling diagram illustrating IMS registration and SIP session establishment in the PS domain before the user equipment initiates the reverse SRVCC handover in the method for processing the reverse single wireless voice call continuity according to the embodiment of the present invention. In the signaling diagram of this embodiment, a specific flow of IMS registration and SIP session establishment performed by the UE in the PS domain network in advance is described by taking an example that the UE does not support the DTM or UTMS mode and the first network element of the PS domain is the ATCF/ATGW. As shown in fig. 3, before initiating the reverse SRVCC handover procedure, the preparation process performed in the PS domain network by the UE in this embodiment specifically includes the following steps:

step 300, UE sends attach request to SGSN;

step 301, SGSN returns attach response to UE;

step 302, UE sends a primary PDP activation request to SGSN;

step 303, the SGSN returns a primary PDP activation response to the UE;

step 304, UE sends auxiliary PDP activating request to SGSN;

step 305, the SGSN returns a secondary PDP activation response to the UE;

wherein, the steps 304 and 305 are optional. The secondary PDP may trigger a Policy and Charging Rules Function (PCRF) to initiate bearer establishment when the SCC AS/ATCF receives the SIP session establishment request.

In this embodiment, it is described by taking an example that the UE does not support the DTM or UTMS mode, that is, the UE cannot support the voice bearer of the CS domain and the voice bearer of the PS domain at the same time, so that the IMS registration in the PS domain performed by the UE before the reverse SRVCC handover must be performed before the UE initiates the voice call of the CS domain network and establishes the CS domain voice session with the opposite UE. In practical applications, the UE may perform the preparation operation in the PS domain just after starting up the power-on.

Specifically, in this embodiment, the registration of the UE in the PS domain network may be specifically divided into two procedures: the first process is registration of the UE in the PS domain network on the SGSN device, and the second process is IMS registration of the UE, and then the SIP voice call process is initiated. In the first registration process, the steps 300 and 305 may be specifically included. Optionally, in the attach request sent by the UE to the SGSN, the UE may also carry CodeC type (CodeC) information supported by default in the PS domain network in the attach request, and based on the CodeC information, the SGSN may know the CodeC type supported by the UE in the PS domain network.

After the UE completes registration in the PS domain network on the SGSN, the UE may further perform registration of the IMS on the SCC AS based on the registration information, and specifically, the registration procedure of the IMS may specifically include the following steps:

step 306, the UE sends an IMS registration request to the ATCF through the SGSN;

optionally, in this step, after receiving the IMS registration request sent by the UE, the SGSN may also send the IMS registration request to the ATCF through a Gateway GPRS Support Node (GGSN).

Step 307, the ATCF anchors the IMS registration to itself;

step 308, the ATCF allocates STN-SR information to the UE, and forwards the STN-SR carried in the IMS registration request to the SCC AS by querying a Call session control Function (I/S-CSCF);

step 309, the SCC AS updates the STN-SR of the UE to the HSS;

step 310, the HSS updates the STN-SR of the UE to the SGSN;

after the UE completes the registration of the PS domain on the SGSN, optionally, the UE may also initiate an IMS registration procedure to the SCC AS, and further initiate an SIP session establishment procedure, and establish a reserved VOIP voice bearer corresponding to the UE in the PS domain network in advance through the SIP session establishment procedure with the SCC AS. Specifically, in this embodiment, the UE first needs to anchor the IMS registration request to the ATCF network element to initiate establishment of the SIP session through the ATCF. In the anchoring process, an IMS registration request can be sent to the ATCF through the UE, and the ATCF anchors the IMS registration process to the ATCF after receiving the IMS registration request. Further, after the ATCF anchors the IMS registration process to itself, the STN-SR identifier of the UE in the PS domain network may be allocated to the UE, and the STN-SR is carried in the IMS registration request and forwarded to the SCC AS through the I/S-CSCF, so that the SCC AS updates the STN-SR identifier allocated to the UE to the database HSS, and further updates the identifier to the SGSN.

Step 311, the UE sends an SIP session establishment request to the ATCF;

step 312, the ATCF anchors the SIP session on the ATGW, so that the ATGW allocates the first information for carrying the VOIP voice service to the UE;

step 313, the ATCF forwards the SIP session establishment request to the SCC AS through the I/S-CSCF;

after the UE anchors the IMS registration request to the ATCF, the ATCF may further anchor the SIP session to the ATCF/ATGW when the UE sends a SIP session establishment request to the ATCF, and the ATGW allocates an address and/or information, i.e., first information, for carrying the VOIP voice service of the UE to the UE in the anchoring process. Specifically, after receiving a SIP session establishment request of the UE and anchoring the SIP session to the ATGW, the ATCF forwards the SIP session establishment request to the SCC AS through the I/S-CSCF, so that the SCC AS completes configuration of a UE context and returns information configured for the UE to the ATCF through the I/S-CSCF. Optionally, in this embodiment, the ATCF may terminate the SIP session establishment request message on the ATCF.

In particular, since the purpose of the UE-initiated SIP session establishment request is not really to establish a SIP session with the opposite UE, the pre-established SIP session connection may not play any substantial role until the UE does not initiate a handover of voice traffic from the CS domain network to the PS domain network, which may simply allocate corresponding resources for the UE in the core network of the PS domain network without any data transmission. However, once the UE initiates the reverse SRVCC handover procedure of the voice service, in the reverse SRVCC handover procedure, the UE can quickly switch the voice service to the VOIP voice of the PS domain based on the pre-allocated resources, and perform the subsequent domain switching procedure of the voice service, so that it is not necessary to temporarily initiate an SIP session in the subsequent domain switching procedure, and establish a VOIP voice bearer, which is equivalent to accelerating the speed of the subsequent domain switching procedure.

Therefore, in the SIP session establishment request sent by the UE through the ATCF, the UE may carry reverse SRVCC indication information, where the reverse SRVCC indication information is used to finally indicate that the SIP session established by the SCC AS at this time is used in a subsequent reverse SRVCC handover procedure, so AS to indicate that when the SCC AS establishes the SIP session for the UE according to the SIP session establishment request, it only needs to process the SIP session establishment request message locally, and does not need to initiate a real voice call to the UE at the opposite end, and even if there is no data transfer on the reserved SIP session connection for a long time, the release process of the resource information of the UE is not actively triggered.

In practical application, the UE carrying the reverse SRVCC indication information in the SIP session establishment request sent to the SCC AS may be specifically implemented in the following two ways: the UE may separately carry an indication information, such as an rSRVCC indication information, in the SIP session establishment request; or, the UE may also carry a special called number in the SIP session establishment request sent to the SCC AS, so AS to indicate that the SCC AS knows that the SIP session is used for the reverse SRVCC handover when receiving the SIP session establishment request carrying a similar called number.

Further preferably, in the process that the UE sends the SIP session establishment request to the SCC AS through the SGSN, the UE may send another indication information to the SGSN, in addition to finally sending the reverse SRVCC indication information to the SCC AS. The indication information is used for indicating the SGSN not to initiate the RAB establishment process after the SIP session of the UE in the PS domain network is established. Since the substantial role of establishing the SIP session connection for the UE before the reverse SRVCC handover is to prepare for the subsequent reverse SRVCC handover procedure, and no transmission of any voice data of the UE is performed on the SIP session connection before the reverse SRVCC handover procedure is performed, the SGSN also does not need to initiate a substantial RAB establishment procedure, thereby avoiding waste of resources. Specifically, the method for the UE to send the indication information to the SGSN may also refer to the description in the above embodiment, and is not described herein again.

It should be noted that, if the UE does not report the CodeC information supported in the PS domain network to the SGSN in the attach procedure to the SGSN, optionally, in the signaling interaction process of SIP session establishment between the UE and the SCC AS in this step, the UE may also negotiate the CodeC information of the UE in the PS domain network with the SCC AS, and after the negotiation is successful, the SCC AS carries the negotiated CodeC information in the SIP response message and returns the information to the UE. In addition, information such AS a destination address used for identifying service transmission of the UE in the PS domain network may also be negotiated by the UE and the SCC AS during the signaling interaction, and the SCC AS carries the negotiated address information in the SIP response message, and returns the address information to the UE in cooperation with the CodeC information.

Step 314, SCC AS returns a call response message to ATCF through I/S-CSCF; the call response message may include configuration information about the UE, such as a Correlation-MSISDN (C-MISDN);

after the SCC AS completes the processing of the SIP session establishment request sent by the UE, a call response message is returned to the ATCF through the I/S-CSCF. Optionally, in the returned call response message, the SCC AS may further return the C-MSISDN number, which is allocated to the UE and corresponds to the SIP Session established by the UE, to the ATCF, and return a special number, which is allocated to the UE, for example, an rSRVCC Session Transfer Identifier (rSRVCC Session Transfer Update-Session Transfer Identifier, abbreviated AS rSRVCC ATU-STI), to the ATCF, where the ATCF stores the special number and the C-MSISDN number returned by the SCC AS, and at the same time, the ATCF directly returns the call response message to the UE, where the special number and the C-MSISDN number are not carried, and at this time, a voice bearer between the UE and the ATGW is established.

Step 315, the UE and SCC AS establish a reserved VOIP voice bearer in the PS domain network;

after the IMS procedure of the PS domain network is completed, optionally, the UE may also establish a reserved VOIP voice bearer in the PS domain network with the SCC AS, specifically, the establishment of the PS media plane between the UE and the SGSN, the SGW, the PGW, and the ATGW is completed, and the reserved VOIP voice bearer may be used in the subsequent reverse SRVCC handover process. The pre-established reserved VOIP voice bearer is used in the subsequent reverse SRVCC switching process and is in a suspended state before switching, and the UE does not need to establish the VOIP voice bearer in the process of really initiating the reverse SRVCC switching by pre-establishing the suspended VOIP voice bearer, thereby accelerating the speed of switching the voice service to the PS domain network.

Step 316, the UE initiates a CS domain voice call, and establishes a CS domain voice session with the UE at the opposite end.

After the UE completes IMS registration in the PS domain and pre-establishes a reserved VOIP voice bearer with the SCC AS, the UE can send a voice call of the CS domain to the opposite-end UE according to a conventional CS domain voice session flow, so AS to establish a CS domain voice session with the opposite-end UE.

It should be noted that, in the process of registering the UE in the PS domain network in this embodiment, if the DTM mode is supported by the UE, that is, the voice service of the UE can be simultaneously carried in two different types of the CS domain and the PS domain, in the above step, the registration of the UE in the PS domain network can complete the establishment of the voice session of the CS domain in the CS domain network by the UE, that is, the UE first establishes a normal voice session in the CS domain network, and then allocates the required resources to the UE in the PS domain network, so as to carry the voice service in the CS domain network, without the occurrence of a situation that the registration of a new voice service affects the voice service in the original CS domain network.

Fig. 4 is a signaling diagram of a third embodiment of a processing method for reverse single wireless voice call continuity according to the present invention. In this embodiment, the specific procedure of performing the reverse SRVCC handover on the UE is described by taking the UE not supporting the DTM or the UTMS mode and the first network element of the PS domain as the ATCF/ATGW as an example. It should be noted that, for the first network element being the ATCF/ATGW, in the embodiment of the present invention, the process of establishing the forwarding channel between the ATCF/ATGW and the rSRVCC MSC may be established under control of the MME, or established by the rSRVCC MSC actively querying related information from the HSS. It should be noted that, in practical application, the ATCF and the ATGW are generally integrally configured, so in this embodiment, the first network element ATGW is described as ATCF/ATGW, and signaling messages sent to the ATGW by representing other network elements may be forwarded to the ATGW through the ATCF.

As shown in fig. 4, the method includes the following steps:

step 400, UE carries out IMS registration in PS domain network and establishes SIP session so as to make PS domain network distribute resource information for UE in advance;

step 401, UE initiates a voice call of CS domain, and establishes a CS domain voice session with an opposite terminal UE;

the specific process of the above step 400 can be referred to the specific description of the previous signaling diagram. The UE registers in the PS domain network in advance and establishes SIP session connection before the reverse SRVCC handover is carried out, so that the PS domain network allocates the reserved resource information for the UE in advance. Further, on the basis of the pre-allocated resource information, the UE may also pre-establish a reserved VOIP voice bearer for the voice service in the PS domain network. In addition, in the embodiment, the UE does not support the DTM or the UTMS mode as an example, so that the UE must perform the registration process in the PS domain network in advance before the normal CS domain voice session establishment process, so as to avoid the situation that the registration of the new voice service affects the voice service in the original CS domain network.

Step 402, a Radio Network Subsystem (RNS)/Base Station controller System (BSS) sends a handover request to a serving MSC;

in this embodiment, since it is assumed that the UE does not support the DTM or the UTMS mode, that is, the UE can only support one type of voice bearer at the same time, in the process of initiating the reverse SRVCC handover by the RNS/BSS, only the CS domain voice bearer needs to be handed over, and thus in this step, the RNS/BSS only needs to send a handover request to the serving MSC. However, it should be noted that, in this embodiment, if the UE supports the DTM mode or the UTMS mode, in this step, the RNS/BSS needs to send a handover request to the serving MSC and the SGSN at the same time.

Optionally, when the BSS/RNS sends the handover request to the serving MSC, the BSS/RNS may further carry reverse SRVCC indication information in the handover request, so as to notify the MME or the rsrvcmsc that the handover is rSRVCC through the serving MSC, and in a subsequent flow, the MME may contact a Home Subscriber Server (HSS) according to the indication information, thereby obtaining the identification information of the corresponding SGSN.

Step 403, the serving MSC forwards the handover request to the rSRVCC MSC;

step 404, the rSRVCC MSC forwards the switching request to the MME;

after receiving the switching request of the RNS/BSS, the serving MSC forwards the switching request (rSRVCC CSto PS request) to the rSRVCC MSC, and in order to respond to the switching request, the rSRVCC MSC allocates second information such as an address and/or a port for the UE.

Step 405, MME sends an identification query request to HSS to obtain the identification of SGSN served by UE;

step 406, the HSS returns the identifier of the SGSN corresponding to the UE to the MME;

after receiving the handover request forwarded by the rSRVCC MSC, in order to enable the rSRVCC MSC to address the corresponding ATCF/ATGW to interact address and/or port information with the ATCF/ATGW, thereby establishing a forwarding channel, the MME needs to first acquire the identifier of the SGSN corresponding to the UE from the database HSS, so as to acquire STN-SR information and related voice bearer information of the UE in the PS domain network from the corresponding SGSN, so as to address the corresponding ATCF/ATGW according to the STN-SR.

Therefore, in this embodiment, after receiving the handover request forwarded by the rSRVCC MSC, the MME sends an identifier query request message to the HSS, where the identifier query request message may specifically be a location update request or other types of request messages, and the identifier query request message carries an identifier of the UE to indicate the HSS to return an identifier of an SGSN to which the specified UE belongs. And after receiving the location updating request carrying the UE identification, the HSS queries the appointed UE in the local database and returns the queried SGSN identification corresponding to the UE to the MME. Optionally, the identity request message sent by the MME to the HSS may also carry srvcc indicator information to notify the HSS that the query of this time is used in an rSRVCC handover operation.

Step 407, the MME acquires context information of the UE from the SGSN;

after acquiring the SGSN identification corresponding to the UE, the MME addresses the corresponding SGSN and performs signaling interaction with the SGSN to acquire the context information of the UE from the corresponding SGSN, wherein the context information comprises STN-SR information and CodeC information registered by the UE in a PS domain network.

Step 408, the MME indicates the ENB to allocate access switching resources for the UE;

step 409, the ENB sends confirmation information to the MME to confirm that the access switching resource allocation is completed;

at this time, the MME has already acquired the context information of the UE, and optionally, in order to enable the UE to smoothly access the PS domain network and complete the access operation in the PS domain network, the MME may further instruct the ENB of the PS domain network to prepare the resource for access handover for the UE at this time, and after the resource allocation is completed, the ENB sends a confirmation message to the MME to notify that the resource allocation for access handover prepared for the UE is completed.

Step 410, the MME sends a switching response message to the rSRVCC MSC, wherein the switching response message carries the acquired context information of the UE;

and after the ENB sends the confirmation message to the MME, and the MME knows that the ENB completes the allocation of the access handover resources for the UE, the MME may further return a handover response message to the rSRVCC MSC, where the handover response message carries the context information of the UE acquired from the SGSN in the step 407, that is, the STN-SR and CodeC information registered in the PS domain network by the UE in the previous registration process, so as to forward the context message of the UE to the rSRVCC MSC through the handover response message. Wherein, the Codec information is optional information. Based on the CodeC information, the rSRVCC MSC can perform corresponding encoding operation on the uplink voice data when forwarding the uplink voice data of the UE to the ATGW after the forwarding channel between the rSRVCC MSC and the ATGW is established, and then forward the encoded uplink voice data to the UE.

Step 411, the rSRVCC MSC returns a switching response message to the RNS/BSS through the service MSC;

in order to complete the access operation of the UE in the RNS/BSS as soon as possible, the rSRVCC MSC also forwards the handover response message through the MSC to inform the RNS/BSS that the access handover resource allocation prepared for the UE has been completed.

Step 412, the rSRVCC MSC sends SIP message to ATCF/ATGW, wherein the SIP message carries the second information distributed by the rSRVCC MSC;

step 413, the ATCF/ATGW returns an SIP response message to the rSRVC MSC, where the SIP response message carries the first information allocated by the ATCF/ATGW;

specifically, after the rSRVCC MSC obtains the context information of the UE, since the UE already anchors the IMS registration to the ATCF in the pre-registration process of the UE, the rSRVCC MSC can directly address the corresponding ATCF/ATGW with the STN-SR information at this time to interact with the address and/or port information of the ATCF/ATGW, thereby establishing a forwarding channel with the ATCF/ATGW.

Step 414, the RNS/BSS sends a handover command to the UE;

step 415, the UE is accessed into the ENB;

step 416, the ENB sends a handover complete message to the MME;

and when the rSVCC MSC and the ATCF/ATGW exchange address and/or port information with each other, after the RNS/BSS receives a switching response message sent by the MSC, in order to complete the access of the UE in the PS domain network as soon as possible, the RNS/BSS sends a switching command to the UE to instruct the UE to carry out the access operation of the PS domain network (EUTRAN), so that the UE utilizes the access switching resources distributed by the ENB for the UE to smoothly access the ENB, namely the PS domain network, and the access flow of the network is completed. And after the access flow of the UE in the ENB is completed, the ENB sends a handover completion message to the MME so as to inform the MME of the message that the access of the MME in the PS domain network is completed.

Until the address and/or port information interaction between the rSVCC MSC and the ATCF/ATGW is completed and the access of the UE to the ENB is completed, a new voice bearing path between the UE and the opposite terminal UE is established, and the downlink voice data sent to the opposite terminal UE by the UE can pass through: the downlink voice bearer path of "UE-ENB-SGW-PGW-ATGW-rSVCC MSC-opposite terminal UE" is sent to the opposite terminal UE, and the uplink voice data sent by the opposite terminal UE to the UE can be sent through the opposite bearer path: "opposite UE-rSVCC MSC-ATGW-PGW-SGW-ENB-UE" (shown as the dashed path below step 416 in fig. 4), is sent to the UE. Therefore, even if the domain switching process is not started or completed, the UE and the opposite-end UE can carry out voice data communication through the bearing path without interrupting the voice service, and the good continuity of the voice service is ensured. Further, the bearer path is established on the basis that the UE completes the PS domain network access, so that the voice service based on the UE can also obtain good voice service quality.

Step 417, the ATCF/ATGW initiates a domain switching process;

step 418, after the domain conversion process is completed, releasing the resources occupied by the forwarding channel.

After the bearer path is successfully established and the UE can perform voice data communication with the peer UE by using the bearer path, in the embodiment of the present invention, in order to truly switch the voice service between the UE and the peer UE to the PS domain network, optionally, the ATCF/ATGW may also initiate a domain switching procedure. The domain switching process is performed on the basis that the UE can perform a normal VOIP voice service with the UE at the opposite end, and thus the speed of the domain switching process does not affect the continuity of the voice service of the UE, specifically, the process of initiating the domain switching by the ATCF/ATGW may be referred to the following fig. 5. It should be noted that, if the UE does not perform the IMS registration procedure in the process of performing the PS domain network registration in advance, the UE must perform the IMS registration in the PS domain network before the ATCF/ATGW initiates the domain switching procedure.

After the domain switching process is completed, the UE may perform voice data communication with the peer UE through a new voice bearer path established in the domain switching process, that is, perform voice service with the peer UE through a downlink voice bearer path of "UE-ENB-SGW-PGW-ATGW-peer UE" and an uplink voice bearer path of "peer UE-ATGW-PGW-SGW-ENB-UE" (as shown by a dotted path below step 417 in fig. 4), so that the rSVCC MSC may control to release resources occupied by the forwarding channel at this time, thereby really completing the reverse SRVCC handover process. Specifically, the process of resource release may be initiated by the ATCF.

In addition, it should be noted that in this embodiment, if the UE does not pre-establish the reserved VOIP voice bearer with the SCC AS in step 315 in the registration process of the PS domain network in advance, that is, the UE does not establish the reserved VOIP voice bearer before the reverse SRVCC handover process, in this embodiment, after the RNS/BSS in step 402 sends the handover request to the MSC, the core network element in the PS domain network will actively trigger the establishment of the VOIP voice bearer of the UE in the PS domain network. Specifically, the triggering of the VOIP voice bearer establishment procedure may be triggered by the SGSN, MSC, ATCF or other core network element in the PS domain network immediately after the step 402. Compared with the scheme of establishing the reserved VOIP voice bearer before the reverse SRVCC switching process, the scheme of establishing the VOIP voice bearer only in the reverse SRVCC switching process avoids the situation that related voice resources need to be reserved in the PS domain network before the reverse SRVCC switching occurs, thereby avoiding the waste of resources in the PS domain network.

In the method for processing reverse single wireless voice call continuity of this embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs IMS registration and initiates establishment of an SIP session in advance in the PS domain network, so as to enable the PS domain network to allocate bearer resource information to the UE in advance, and in the process of switching the voice service from the CS domain network to the PS domain network, the MME controls a forwarding channel between an rSRVCC MSC in the CS domain network and an ATGW in the PS domain network to establish voice data, so that after the UE actually initiates the switching of the voice service from the CS domain network to the PS domain network and rapidly accesses to the PS domain network, the UE can rapidly transmit voice data with an opposite terminal through the established forwarding channel without waiting for completion of a long-time domain switching procedure, the method ensures good voice service continuity in the reverse SRVCC switching process, and further, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 5 is a signaling diagram illustrating a domain switching procedure in the method for processing reverse single wireless voice call continuity according to an embodiment of the present invention. In the signaling diagram of this embodiment, a detailed procedure of interacting address and/or port information between the srvcc MSC and the ATGW is also described, as shown in fig. 5, on the basis of the previous embodiment, after the srvcc MSC returns a handover response message to the RNS/BSS through the serving MSC in step 411, a procedure of interacting port and/port information between the srvcc MSC and the ATGW and a domain switching procedure initiated by the ATCF are specifically as follows:

step 500, the rSRVCC MSC sends SIP message (INVITE message) carrying C-MSISDN number and address and/or port information to ATCF;

step 501, the ATCF configures the ATGW according to the received SIP message;

specifically, after the rSRVCC MSC addresses the corresponding ATCF according to the STN-SR information, the rSRVCC MSC carries the address and/or port information allocated to the UE and the pre-obtained C-MSISDN number in the SIP message and sends the SIP message to the ATCF. The C-MSISDN number is associated with the SIP session pre-established by the UE, and the ATCF can find the SIP session corresponding to the UE according to the C-MSISDN number.

After receiving the SIP message, the ATCF uses the C-MSISDN to associate to the session to be transferred, and then interacts with the ATGW, thereby updating the media surface, and associating the pre-established voice bearer and the newly established bearer, namely the newly established bearer between the rSRVCC MSC and the ATGW.

Step 502, the ATGW returns a configuration response message (Configure ATGW acknowledgement) to the ATCF; wherein the address and/or port information pre-allocated by ATGW for UE is sent to ATCF

Step 503, the ATCF returns an SIP response message to the rSRVCC MSC, wherein the SIP response message carries the address and/or port information of the ATGW;

step 504, the ATCF sends an Access transfer Update (Access transfer Update) message to the SCC AS;

step 505, SCC AS forwards the modification message to the peer UE;

after receiving the CS to PS access transfer message, the ATCF reestablishes a session with the SCC AS, and informs the SCC AS of the CS to PS access transfer. The SCC AS uses rSRVCC ATU-STI to locate the relevant session and establish a new session between ATCF and SCC AS. Meanwhile, the SCC AS associates the newly-established session with the SIP session pre-established by the UE during registration, and the association operation is usually implemented by the C-MSISDN.

Optionally, the SCC AS updates the media plane of the UE at the opposite end, so that the UE at the opposite end can directly send the voice data to the ATGW. Meanwhile, the opposite terminal UE can directly receive the voice data sent by the ATGW.

Step 506, the opposite terminal UE returns a modification response message to the SCC AS;

step 507, the SCC AS returns an access switching modification response message to the ATCF;

at this time, a new voice bearer path between the UE and the UE at the opposite end is established, and the new voice bearer path after domain switching is specifically a downlink voice bearer path of "UE-ENB-SGW-PGW-ATGW-UE at the opposite end" and an uplink voice bearer path of "UE-ATGW-PGW-SGW-ENB-UE at the opposite end".

Fig. 6 is a signaling diagram of a fourth embodiment of a processing method for reverse single wireless voice call continuity according to the present invention. The procedure of the reverse SRVCC handover in this embodiment is performed based on the UE pre-registration described in the embodiment and the signaling diagram of fig. 3, and in this embodiment, a specific procedure of the reverse SRVCC handover performed by the UE is described by taking the UE supporting the DTM or the UTMS mode and taking the first network element of the PS domain as the ATCF/ATGW as an example. In this embodiment, only the process of controlling and establishing the forwarding channel between the ATCF/ATGW and the rSRVCC MSC by the MME is specifically described. It should be noted that the difference between the present embodiment and the embodiment shown in fig. 4 is only that the UE of the present embodiment supports DTM or UTMS mode, but the UE of the above embodiment does not support DTM or UTMS mode, and therefore, in the present embodiment, for the same steps as those of the above embodiment shown in fig. 4, the description of the embodiment corresponding to fig. 4 may be specifically referred to.

As shown in fig. 6, the method includes the following steps:

step 600, UE initiates a CS domain voice call, and establishes a CS domain voice session with an opposite terminal UE;

601, UE carries out IMS registration in PS domain network and establishes SIP session, so that PS domain network distributes resource information for UE in advance;

in this embodiment, the UE supports the DTM or the UTMS mode as an example, so that the registration process of the UE in the PS domain network may be performed after the normal CS domain voice session establishment process in advance, and the situation that the registration of a new voice service affects the voice service in the original CS domain network does not occur.

Step 602, RNS/BSS sends a handover request to a serving MSC and SGSN at the same time;

step 603, the serving MSC forwards the handover request to the rSRVCC MSC;

step 604, the rSRVCC MSC forwards the handover request to the MME;

step 605, the SGSN forwards the handover request carrying the context information of the UE to the MME;

since the UE supports the DTM or UMTS mode in this embodiment, the MME does not need to send an identifier query request to the HSS to obtain the identifier of the SGSN corresponding to the UE from the HSS through the location update request, so as to address the SGSN. In this embodiment, the SGSN actively forwards the context information of the UE to the MME upon receiving the handover request sent by the RNS/BSS, so that the MME can automatically obtain the context information pre-registered by the UE in the PS domain network without sending an identifier query request to the HSS.

Step 606, MME instructs ENB to allocate access switching resource for UE;

step 607, the ENB sends confirmation information to the MME to confirm that the access handover resource allocation is completed;

at this time, in order to enable the UE to access the PS domain network, the MME may instruct the ENB of the PS domain network to prepare the resource for access handover for the UE, and after the resource allocation is completed, the ENB may transmit a confirmation message to the MME to inform that the resource allocation for access handover prepared for the UE is completed.

Step 608, MME sends handover response message to rSRVCC MSC, where it carries context information of UE;

step 609, the rSRVCC MSC sends SIP message to ATCF/ATGW, wherein the SIP message carries the second information distributed by the rSRVCC MSC;

step 610, ATCF/ATGW returns SIP response message to rSRVC MSC, wherein the SIP response message carries the first information distributed by ATCF/ATGW;

specifically, after the rSRVCC MSC learns the context information of the UE, since the UE already anchors the IMS registration to the ATCF in the pre-registration process of the UE, at this time, the rSRVCC MSC can directly address the corresponding ATCF/ATGW with the STN-SR information to interact with the address and/or port information of the ATCF/ATGW, thereby establishing a forwarding channel with the ATCF/ATGW.

Step 611, the rSRVCC MSC returns a switching response message to the RNS/BSS through the service MSC;

step 612, the MME returns a handover response message to the RNS/BSS through the SGSN;

meanwhile, after the step 607, after knowing that the ENB is the access handover resource allocation of the UE, the MME also returns a handover response message to the SGSN, so that the SGSN forwards the handover response message to the RNS/BSS to inform the RNS/BSS that the access handover resource information is already allocated to the UE in the ENB.

Step 613, the RNS/BSS sends a handover command to the UE;

step 614, the UE is accessed into the ENB;

step 615, the ENB sends a handover complete message to the MME;

step 616, the MME sends a bearer modification request to the ATCF/ATGW;

step 617, the ATCF/ATGW returns a bearer modification response message to the MME;

until the address and/or port information interaction between the rSVCC MSC and the ATCF/ATGW is completed and the access of the UE to the ENB is completed, a new voice bearing path between the UE and the opposite terminal UE is established, and the downlink voice data sent to the opposite terminal UE by the UE can pass through: the downlink voice bearer path of "UE-ENB-SGW-PGW-ATGW-rSVCC MSC-opposite terminal UE" is sent to the opposite terminal UE, and the uplink voice data sent by the opposite terminal UE to the UE can be sent through the opposite bearer path: "opposite end UE-rSVCC MSC-ATGW-PGW-SGW-ENB-UE" is sent to the UE. Therefore, even if the domain switching process is not started or completed, the UE and the opposite-end UE can carry out voice data communication through the bearing path without interrupting the voice service, and the good continuity of the voice service is ensured. Further, the bearer path is established on the basis that the UE completes the PS domain network access, so that the voice service based on the UE can also obtain good voice service quality.

Step 618, the ATCF/ATGW initiates the domain switching process;

step 619, after the domain switching process is completed, releasing the resources occupied by the forwarding channel.

After the bearer path is successfully established and the UE can perform voice data communication with the peer UE by using the bearer path, in the embodiment of the present invention, in order to truly switch the voice service between the UE and the peer UE to the PS domain network, optionally, the ATCF/ATGW may also initiate a domain switching procedure. After the domain switching process is completed, the UE can perform voice data communication with the opposite-end UE through a new voice bearer path established in the domain switching process, that is, perform voice service with the opposite-end UE through a downlink voice bearer path of "UE-ENB-SGW-PGW-ATGW-opposite-end UE" and an uplink voice bearer path of "opposite-end UE-ATGW-PGW-SGW-ENB-UE", so that the rSVCC MSC can control to release resources occupied by the forwarding channel at this time, thereby really completing the reverse SRVCC handover process. Specifically, the process of resource release may be initiated by the ATCF.

Fig. 7 is a signaling diagram of a fifth embodiment of a processing method for reverse single wireless voice call continuity according to the present invention. In this embodiment, the specific procedure of performing the reverse SRVCC handover on the UE is described by taking the UE not supporting the DTM or the UTMS mode and the first network element of the PS domain as the ATCF/ATGW as an example. It should be noted that, for the first network element being the ATCF/ATGW, in the embodiment of the present invention, the process of establishing the forwarding channel between the ATCF/ATGW and the rSRVCC MSC may be established under control of the MME, or established by the rSRVCC MSC actively querying the relevant information from the HSS, and in this embodiment, the process established by the rSRVCC MSC actively querying the relevant information from the HSS is specifically described. It should be noted that, in practical application, the ATCF and the ATGW are generally integrally configured, so in this embodiment, the first network element ATGW is also described as ATCF/ATGW, and a signaling message sent to the ATGW by representing another network element may be forwarded to the ATGW through the ATCF.

As shown in fig. 7, the method includes the following steps:

step 700, UE carries out IMS registration in PS domain network and establishes SIP session, so that PS domain network distributes resource information for UE in advance;

step 701, UE initiates a voice call of CS domain, and establishes a CS domain voice session with an opposite terminal UE;

in this embodiment, the UE does not support the DTM or UTMS mode, so that the UE must perform the registration process in the PS domain network before the normal CS domain voice session establishment process in advance, so as to avoid the situation that the registration of the new voice service affects the voice service in the original CS domain network.

Step 702, the RNS/BSS sends a handover request to the serving MSC;

in this embodiment, since it is assumed that the UE does not support the DTM or the UTMS mode, that is, the UE can only support one type of voice bearer at the same time, in the process of initiating the reverse SRVCC handover by the RNS/BSS, only the CS domain voice bearer needs to be handed over, and thus in this step, the RNS/BSS only needs to send a handover request to the serving MSC. Optionally, the BSS/RNS may also carry the reverse SRVCC indication information in the handover request when sending the handover request to the serving MSC.

Step 703, the serving MSC forwards the handover request to the rSRVCC MSC;

step 704, the rSRVCC MSC sends an identifier query request to the HSS, where the identifier carries the identifier of the UE;

step 705, the HSS returns the identifier of the SGSN corresponding to the UE to the rSRVCC MSC;

in this embodiment, after receiving the handover request forwarded by the serving MSC, the rSRVCC MSC directly queries and acquires the identification information of the SGSN corresponding to the UE from the database HSS by sending an identification query request carrying the identification of the UE to the HSS, not through the MME. The identification query request message may specifically be a location update request or other type of request message. Optionally, the identity request message sent by the MME to the HSS may also carry srvcc indicator information to notify the HSS that the query of this time is used in an rSRVCC handover operation.

Step 706, the rSRVCC MSC forwards the handover request to the specified SGSN;

step 707, the SGSN returns a response message to the rSRVCC MSC, where the response message carries context information of the UE;

after acquiring the SGSN identifier corresponding to the UE, the rSRVCC MSC addresses the corresponding SGSN, and forwards the handover request to the SGSN, where the handover request may carry indication information to indicate the SGSN to return context information of the UE, where the context information includes STN-SR information and CodeC information registered by the UE in the PS domain network.

Step 708, the SGSN forwards the handover request to the MME;

step 709, the MME instructs the ENB to allocate access switching resources for the UE;

step 710, the ENB sends confirmation information to the MME to confirm that the access switching resource allocation is completed;

the SGSN returns a response message to the rSRVCC MSC, and simultaneously forwards the switching request message to the MME, and in order to enable the UE to be smoothly accessed into the PS domain network and complete the access operation in the PS domain network, the MME can also indicate the ENB of the PS domain network to prepare the resources for accessing and switching the UE at the moment, and after the resource allocation is completed, the ENB sends a confirmation message to the MME to inform that the resource allocation for accessing and switching the UE is completed.

Step 711, the rSRVCC MSC sends an SIP message to the ATCF/ATGW, wherein the SIP message carries second information allocated by the rSRVCC MSC;

step 712, the ATCF/ATGW returns an SIP response message to the rSRVC MSC, where the SIP response message carries the first information allocated by the ATCF/ATGW;

meanwhile, after the above step 707, the rSRVCC MSC obtains the context information of the UE, and since the UE already anchors the IMS registration to the ATCF in the pre-registration process of the UE, the rSRVCC MSC can directly address the corresponding ATCF/ATGW according to the STN-SR information in the context information to interact with the address and/or port information of the ATCF/ATGW, thereby establishing a forwarding channel with the ATCF/ATGW.

Step 713, the MME sends a switching response message to the rSRVCC MSC;

step 714, the rSRVCC MSC returns a switching response message to the RNS/BSS through the service MSC;

step 715, the RNS/BSS sends a handover command to the UE;

step 716, the UE accesses to the ENB;

step 717, the ENB transmits a handover complete message to the MME;

and when the rSVCC MSC and the ATCF/ATGW exchange address and/or port information with each other, after the RNS/BSS receives a switching response message sent by the MGW, in order to complete the access of the UE in the PS domain network as soon as possible, the RNS/BSS sends a switching command to the UE to instruct the UE to carry out the access operation of the PS domain network (EUTRAN), so that the UE utilizes the access switching resources distributed by the ENB for the UE to smoothly access the ENB, namely the PS domain network, and the access flow of the network is completed. And after the access flow of the UE in the ENB is completed, the ENB sends a handover completion message to the MME so as to inform the MME of the message that the access of the MME in the PS domain network is completed.

Step 718, the ATCF/ATGW initiates a domain switching procedure;

step 719, after the domain conversion process is completed, releasing the resources occupied by the forwarding channel.

After the domain switching process is completed, the UE can perform voice data communication with the opposite-end UE through a new voice bearer path established in the domain switching process, that is, perform voice service with the opposite-end UE through a downlink voice bearer path of "UE-ENB-SGW-PGW-ATGW-opposite-end UE" and an uplink voice bearer path of "opposite-end UE-ATGW-PGW-SGW-ENB-UE", so that the rSVCC MSC can control to release resources occupied by the forwarding channel at this time, thereby really completing the reverse SRVCC handover process. Specifically, the process of resource release may be initiated by the ATCF.

In addition, it should be noted that in this embodiment, if the UE does not pre-establish the reserved VOIP voice bearer with the SCC AS in step 315 in the registration process of the PS domain network in advance, that is, the UE does not establish the reserved VOIP voice bearer before the reverse SRVCC handover process, in this embodiment, after the RNS/BSS of step 702 sends the handover request to the MSC, the core network element in the PS domain network will actively trigger the establishment of the VOIP voice bearer of the UE in the PS domain network. Specifically, the triggering of the VOIP voice bearer establishment procedure may be triggered by the SGSN, MSC, ATCF or other core network element in the PS domain network immediately after step 702.

In the method for processing reverse single wireless voice call continuity of this embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs IMS registration in the PS domain network in advance and initiates establishment of an SIP session, so that the PS domain network allocates bearer resource information to the UE in advance, and in the process of switching the voice service from the CS domain network to the PS domain network, the PS domain network reserves bearer information allocated to the UE in advance, and the rSRVCC MSC in the CS domain network actively queries related information from the HSS to establish a forwarding channel between the rSRVCC MSC and the ATGW, so that after the UE actually initiates the switching of the voice service from the CS domain network to the PS domain network and rapidly accesses to the PS domain network, the UE can rapidly transmit voice data with the opposite terminal through the established forwarding channel without waiting for completion of a long-time domain switching process, the method ensures good voice service continuity in the reverse SRVCC switching process, and further, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 8 is another signaling diagram illustrating the MS registration and the SIP session establishment procedure performed by the ue in the PS domain before initiating the reverse SRVCC handover in the processing method for reverse single radio voice call continuity according to the embodiment of the present invention. In the signaling diagram of this embodiment, a specific procedure of the UE performing IMS registration and establishing an SIP session in the PS domain network in advance is described by taking the UE supporting the DTM or UTMS mode and the first network element of the PS domain as the PGW as an example. As shown in fig. 8, the registration and SIP session establishment procedure performed in the PS domain network before the UE initiates the reverse SRVCC handover procedure in this embodiment specifically includes the following steps:

step 800, UE initiates a CS domain voice call, and establishes a CS domain voice session with an opposite terminal UE;

in this embodiment, the UE supports the DTM or UTMS mode as an example, and the UE can simultaneously support the voice bearer of the CS domain and the voice bearer of the PS domain, so that the IMS registration and the SIP session establishment initiated in the PS domain by the UE before the reverse SRVCC handover can be performed on the basis that the UE initiates the voice call of the CS domain network and establishes the CS domain voice session with the opposite UE.

Specifically, in this embodiment, after the UE completes the CS session establishment with the UE on the opposite side through the regular CS session procedure, the IMS registration and the SIP session establishment performed in the PS domain network may be specifically divided into two procedures. The first procedure is a registration procedure of the UE in the PS domain network performed on the SGSN device, and the registration procedure of the PS domain network may specifically include the following steps:

step 801, UE sends an attach request to SGSN;

step 802, SGSN returns an attach response to the UE;

step 803, the UE sends a primary PDP activation request to the SGSN;

step 804, SGSN returns a primary PDP activation response to UE;

step 805, the UE sends a secondary PDP activation request to the SGSN;

step 806, the SGSN returns a secondary PDP activation response to the UE;

the above steps 805 and 806 are optional steps in which the UE performs the secondary PDP activation procedure on the SGSN. Specifically, in the attach request sent by the UE to the SGSN, the UE may also carry CodeC type (CodeC) information supported by default in the PS domain network in the attach request, and based on the CodeC information, the SGSN may know the CodeC type supported by the UE in the PS domain network.

Further optionally, in the primary PDP activation request or the secondary PDP activation request sent by the UE to the SGSN, the UE may further carry indication information in the primary PDP activation request or the secondary PDP activation request to indicate the SGSN to acquire the first information of the address and/or the port from the PGW of the PS domain network. Therefore, under the indication of the indication information, the SGSN indicates the PGW to allocate resource information required by the UE in the PS domain network to the UE, and returns the resource information to the SGSN, and the first information can be used for establishing a forwarding channel in the subsequent reverse SRVCC handover procedure. It should be noted that, in the first information, the port information allocated by the PGW to the UE may be a public port dedicated to establishing a forwarding channel in the reverse SRVCC handover, and if the port is a dedicated public port, the port information allocated by the PGW to the UE may also be directly configured on the MME or the rSRVCC MSC.

After the UE completes registration in the PS domain network on the SGSN, the UE may further perform IMS registration on the SCC AS based on the registration information, and in the IMS registration process, the SCC AS allocates unique STN-SR information to the UE. And after the IMS registration procedure is completed, the UE may also initiate an SIP session establishment procedure on the SCC AS, and specifically, the SIP session establishment procedure may specifically include the following steps:

step 807, the UE sends a SIP session establishment request to the SCC AS;

step 808, the SCC AS returns an SIP response message to the UE, carrying resource information allocated to the UE;

after the UE completes registration of the PS domain on the SGSN, further, the UE may also initiate a SIP session establishment procedure to the SCC AS, and establish a reserved SIP session connection in the PS domain network in advance through the SIP session establishment procedure with the SCC AS. Specifically, the purpose of the UE initiating the SIP session establishment request is not really to establish a SIP session with the opposite UE, and the pre-established SIP session may not play any substantial role before the UE does not initiate a handover of voice traffic from the CS domain network to the PS domain network, which may be simply to allocate corresponding resources for the UE in the core network of the PS domain network without any data transmission. However, once the UE initiates the reverse SRVCC handover procedure of the voice service, in the reverse SRVCC handover procedure, the UE can quickly switch the voice service to the VOIP voice of the PS domain based on the pre-allocated resources, and perform the subsequent domain switching procedure of the voice service, so that it is not necessary to temporarily initiate an SIP session in the subsequent domain switching procedure, and establish a VOIP voice bearer, which is equivalent to accelerating the speed of the subsequent domain switching procedure.

Therefore, in the SIP session establishment request sent by the UE to the SCC AS, the UE may carry reverse SRVCC indication information, where the reverse SRVCC indication information is used to indicate that the SIP session established by the SCC AS at this time is used in a subsequent reverse SRVCC handover procedure, so AS to indicate that the SCC AS does not need to initiate a real call to the opposite UE when establishing the SIP session for the UE according to the SIP session establishment request, and is used to indicate that the SCC AS does not actively trigger a release process of the resource information of the UE even if there is no data transfer on the reserved SIP session connection for a long time. In practical application, the UE carrying the reverse SRVCC indication information in the SIP session establishment request sent to the SCC AS may be specifically implemented in the following two ways: the UE may separately carry an indication information, such as the srvcc indicator information, in the SIP session establishment request; or, the UE may also carry a special called number in the SIP session establishment request sent to the SCC AS, so AS to indicate that the SCC AS knows that the SIP session is used for the reverse SRVCC handover when receiving the SIP session establishment request carrying a similar called number.

Step 809, the UE establishes a reserved VOIP voice bearer within the PS domain network.

Further, after the UE establishes the SIP session on the SCC AS, optionally, the UE may also pre-establish a reserved VOIP voice bearer for carrying the VOIP voice service of the UE with the SCC AS in the PS domain network, that is, further allocate reserved bearer information for the VOIP voice service to the UE in a core network element of the PS domain network. The pre-established reserved VOIP voice bearer is used in the subsequent reverse SRVCC switching process and is in a suspended state before switching, and the suspended VOIP voice bearer is pre-established, so that the UE does not need to temporarily establish the VOIP voice bearer in the process of really initiating the reverse SRVCC switching by the UE, thereby accelerating the speed of switching the voice service to the PS domain network.

It should be noted that, in the process of registering the UE in the PS domain network in this embodiment, if the UE supports the non-DTM mode, that is, the voice service of the UE cannot be simultaneously carried in two different types of the CS domain and the PS domain, in the above step, the IMS registration performed by the UE in the PS domain network must complete before the UE establishes the voice session of the CS domain in the CS domain network, that is, the UE first allocates the required resources to the UE in the PS domain network, and then establishes a normal voice session in the CS domain network, and carries the voice service in the CS domain network, thereby avoiding the occurrence of a situation that the registration of a new voice service affects the voice service in the original CS domain network.

Fig. 9 is a signaling diagram of a sixth embodiment of a processing method for reverse single wireless voice call continuity according to the present invention. In this embodiment, also taking the example that the UE supports the DTM or UTMS mode and the first network element of the PS domain is the PGW, a specific procedure for performing the reverse SRVCC handover for the UE is described. As shown in fig. 9, the method includes the following steps:

step 900, UE initiates a CS domain voice call and establishes a CS domain voice session with an opposite terminal UE;

step 901, registering and establishing an SIP session in a PS domain network by the UE, so that the PS domain network allocates resource information to the UE in advance;

the specific process of the above steps can be referred to the specific description of the previous signaling diagram. The UE registers in the PS domain network in advance and establishes SIP session connection before reverse SRVCC switching is carried out, so that the PS domain network allocates the reserved resource information for the UE in advance, and further, based on the pre-allocated resource information, the UE can also establish the reserved VOIP voice bearer for the voice service in the PS domain network in advance.

Step 902, RNS/BSS sends handover request to serving MSC and SGSN at the same time;

in this embodiment, it is assumed that the UE supports the DTM or the UTMS mode, that is, supports two types of voice bearers simultaneously, so that in the process of initiating the reverse SRVCC handover by the RNS/BSS, the RNS/BSS must simultaneously switch the two types of bearers, specifically, simultaneously switch the CS voice service and the PS voice service, and in this step, the RNS/BSS needs to simultaneously send a handover request to the MSC and the SGSN. It should be noted that, if the UE does not support the DTM mode in this embodiment, in this step, the RNS/BSS only needs to send a handover request to the MSC.

Step 903, the serving MSC forwards the handover request to the rSRVCC MSC;

step 904, the rSRVCC MSC allocates the second information to the UE, carries the second information in the handover request, and forwards the second information to the MME;

for the serving MSC, in this embodiment, after receiving the handover request of the RNS/BSS, the serving MSC forwards the handover request to the rSRVCC MSC, and notifies the rSRVCC MSC of second information for allocating an address and/or a port to the UE. Therefore, the rSRVCC MSC knows that the UE needs to switch the voice service to the PS domain network at the moment according to the switching request, responds to the switching request, allocates address and/or port information for the UE, and carries second information of the allocated address and/or port in the switching request to be forwarded to the MME.

Step 905, the SGSN forwards the first information pre-allocated by the PGW and the context information of the UE to the MME, carrying the handover request;

for the SGSN, after receiving the handover request of the RNS/BSS, the SGSN also forwards the handover request to the MME, and at the same time, the SGSN also carries the first information of the address and/or the port acquired from the first network element PGW during the IMS registration process in the PS domain network performed in advance by the UE, and the context information registered by the UE in the PS domain network, for example, the STN-SR and CodeC information registered by the UE in the PS domain network, together with the handover request, and forwards the handover request to the MME.

It should be noted that, in this embodiment, if the UE does not support the DTM or the UTMS mode, in this step, the SGSN does not actively forward the first information and the context information of the UE to the MME on the basis of not receiving the handover request sent by the RNS/BSS, so that the MME sends a location update request or other request messages to the HSS in order to obtain the above information from the SGSN, where the location update request or other request messages carry the identifier of the UE, so that the HSS can query the identifier of the corresponding SGSN according to the UE identifier in the location update request and feed the identifier back to the MME, and then the MME further obtains the context information and the first information of the UE from the corresponding SGSN.

Step 906, the MME instructs the ENB to allocate access switching resources for the UE;

step 907, the ENB sends confirmation information to the MME to confirm that the access handover resource allocation is completed;

Step 908, the MME sends a handover response message to the rSRVCC MSC, where the handover response message carries the first information allocated by the PGW and the context information of the UE;

after knowing that the ENB is the access handover resource allocation of the UE is completed, the MME returns a handover response message to the MGW, where the handover response message carries the first bearer information allocated to the forwarding channel by the PGW acquired from the SGSN in the step 905 and the CodeC information registered in the PS domain network by the UE in the pre-registration process, so as to forward the first information allocated by the PGW to the srvcc MSC of the second network element, which is equivalent to informing the srvcc MSC of the address and/or port information of the PGW of the first network element, so that when the rsvcc MSC receives the uplink voice data sent to the UE by the UE of the opposite terminal, the MME can accurately transmit the uplink voice data to the PGW of the first network element according to the address and/or port information, so as to transmit the uplink voice data to the UE. Based on the CodeC information registered by the UE in the PS domain network, the rsrvcmsc can also perform corresponding encoding operation on the uplink voice data before forwarding the uplink voice data of the UE to the PGW, and then forward the encoded uplink voice data to the UE.

Step 909, the rSRVCC MSC returns a handover response message to the RNS/BSS through the serving MSC;

and after receiving the switching response message sent by the MME, the rSRVCC MSC stores the carrying information carried in the switching response message, and further forwards the switching response message to the RNS/BSS through the serving MSC so as to complete the process of switching the CS voice to the PS domain.

Step 910, the MME returns a switching response message to the RNS/BSS through the SGSN;

meanwhile, after the step 407, after knowing that the ENB is the access handover resource allocation of the UE is completed, the MME also returns a handover response message to the SGSN, so that the SGSN forwards the handover response message to the RNS/BSS to inform the RNS/BSS that the access handover resource information is already allocated to the UE in the ENB.

Step 911, the RNS/BSS sends a handover command to the UE;

step 912, accessing the UE to the ENB;

step 913, the ENB sends a handover complete message to the MME;

after receiving the switching response message, the RNS/BSS sends a switching command to the UE to instruct the UE to perform access operation of the PS domain network, so that the UE smoothly accesses to the ENB by using the access switching resources distributed by the ENB for the UE, namely, accesses to the PS domain network, and the network access process is completed. And after the access flow of the UE in the ENB is completed, the ENB sends a handover completion message to the MME so as to inform the MME of the message that the access of the MME in the PS domain network is completed.

Step 914, the MME sends a bearer modification request to the PGW, carrying the second information allocated by the rSRVCC MSC for the UE;

step 915, the PGW returns a bearer modification response message to the MME;

after receiving the handover complete message, the MME sends a bearer modification request to the PGW of the first network element of the PS domain network, where the bearer modification request carries the second information obtained from the rSRVCC MSC of the second network element in step 404, that is, the MME directs the bearer path of the voice service to the UE to the rSRVCC MSC on the PGW, and forwards the address and/or port information of the UE allocated by the rSRVCC MSC to the PGW, so that the PGW modifies the voice bearer path that should be directly directed to the UE at the opposite end to direct to the rSRVCC MSC, thereby establishing a forwarding channel between the PGW and the rSRVCC MSC. Therefore, when the PGW receives downlink voice data sent to the opposite terminal UE by the UE through the ENB, the downlink voice data can be accurately forwarded to the rSRVCC MSC according to the address and/or port information distributed by the rSRVCC MSC for the VOIP voice bearer of the UE, and then sent to the opposite terminal UE. Further, based on the CodeC information of the UE registered in the PS domain network acquired by the rSRVCC MSC in step 408, after receiving the downlink voice data of the UE forwarded by the PGW, the rsrvcmsc may further perform corresponding decoding operation on the downlink voice data before sending the downlink voice data to the peer UE, and then forward the decoded downlink voice data to the peer UE.

So far, a new voice bearer path between the UE and the peer UE is established, downlink voice data sent by the UE to the peer UE may be sent to the peer UE through a downlink voice bearer path of "UE-ENB-SGW-PGW-rSRVCC MSC-serving MSC-peer UE", and uplink voice data sent by the peer UE to the UE may be sent through an opposite bearer path: the opposite end "UE-serving MSC-rSRVCC MS-PGW-SGW-ENB-UE" (shown as the dashed path below step 915 in fig. 9), is sent to the UE. Therefore, even if the domain switching process is not started or completed, the UE and the opposite-end UE can carry out voice data communication through the bearing path without interrupting the voice service, and the good continuity of the voice service is ensured. Further, the bearer path is established on the basis that the UE completes the PS domain network access, so that the voice service based on the UE can also obtain good voice service quality.

It should be noted that, since the UE may be classified into two types, which support DTM or UTMS mode and do not support DTM or UTMS mode, although the embodiment only takes the example that the UE supports DTM or UTMS mode, and describes the procedure of the reverse SRVCC handover, it should be understood that, if the UE does not support DTM or UTMS mode, in the embodiment of the present invention, the difference between the procedure of the reverse SRVCC handover and the procedure that the UE supports DTM mode is as follows:

if the UE does not support the DTM or UTMS mode, the IMS registration process of the UE in the PS domain before switching must be completed before the UE establishes a CS domain voice session with the opposite terminal UE in the CS domain network; in the process of the reverse SRVCC handover, since the UE cannot support two types of voice bearers simultaneously, in step 902, the RNS/BSS only needs to initiate a handover request to the serving MSC once, and does not need to send two handover requests to the SGSN and the serving MSC simultaneously. At this time, since the SGSN does not receive the RNS/BSS sending the handover request, the SGSN cannot carry the first information allocated by the PGW and the context information registered by the UE in the PS domain network to the handover request and forward the handover request to the MME, so that the MME also needs to send a location update request or other request messages to the HSS to obtain, from the HSS, the SGSN storing the first information and other information through the location update request, thereby actively obtaining, from the corresponding SGSN, the first information allocated by the PGW and the upper context information registered by the UE in the PS domain network.

Step 916, the UE initiates a domain switching procedure;

step 917, after the domain switching process is completed, releasing the resources occupied by the forwarding channel.

After the bearer path is successfully established and the UE can perform voice data communication with the peer UE by using the bearer path, in the embodiment of the present invention, in order to truly switch the voice service between the UE and the peer UE to the PS domain network, optionally, the UE may also initiate a domain switching procedure. The domain switching process is performed on the basis that the UE can perform normal VOIP voice service with the opposite-end UE, so that the speed of the domain switching process is high and low, and the continuity of the voice service of the UE is not affected. It should be noted that, if the UE does not perform the IMS registration procedure in the process of performing the PS domain network registration in advance, the UE must perform the IMS registration in the PS domain network before initiating the domain switching procedure.

After the domain switching procedure is completed, the UE may perform voice data communication with the peer UE through a new voice bearer path established in the domain switching procedure, that is, perform voice service with the peer UE through a downlink voice bearer path of "UE-ENB-SGW-PGW-peer UE" and an uplink voice bearer path of "peer UE-PGW-SGW-ENB-UE" (AS shown by a dotted path below step 916 in fig. 9), so that the SCC AS may control to release resources occupied by the forwarding channel at this time, so AS to really complete the reverse SRVCC handover procedure. Specifically, the process of resource release may be initiated by an Interworking Solution Function (IWS), and the IWS sends the indication information of resource release to the MME through the MSC, so that the MME controls to release all resources borne by the VOIP.

In the method for processing continuity of a reverse single wireless voice call of this embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs IMS registration and initiates establishment of an SIP session in advance in the PS domain network, so that the PS domain network allocates bearer resource information to the UE in advance, and in the process of switching the voice service from the CS domain network to the PS domain network, the MME controls establishment of a forwarding channel between the rSRVCC MSC and the PGW by using the bearer information allocated to the UE in advance by the PS domain network, so that after the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and quickly accesses the PS domain network, the UE can quickly transmit voice data with an opposite terminal through the established forwarding channel without waiting for completion of a long-time domain switching procedure, thereby ensuring good voice service continuity in the reverse SRVCC switching process, furthermore, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

Fig. 10 is a schematic structural diagram of a user terminal according to a first embodiment of the present invention. As shown in fig. 10, the ue of this embodiment at least includes a resource information configuration module 11. Specifically, the resource information configuration module 11 is configured to, before the user terminal switches the voice service from the CS domain network to the PS domain network, pre-configure resource information required for switching the voice service in the PS domain network, where the resource information may be used in a process that the user terminal switches the voice service from the CS domain network to the PS domain network. Specifically, by using the pre-configured resource information, a forwarding channel can be established between a first network element of the PS domain network and a second network element of the CS domain network, and the forwarding channel is used for forwarding voice service data between the user terminal and the opposite user terminal after the user terminal accesses to the PS domain network.

Specifically, the specific working processes related to all modules in this embodiment may refer to the related contents disclosed in the related embodiments related to the processing method for reverse single wireless voice call continuity, and are not described herein again.

The user terminal of this embodiment, by allocating the bearer resource information to the UE in advance in the PS domain network before switching the voice service from the CS domain network to the PS domain network, enables the PS domain network to use the reserved bearer information allocated to the UE in advance during the process of switching the voice service from the CS domain network to the PS domain network, and can establish the forwarding channel between the CS domain network and the PS network, so that after the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and quickly accesses to the PS domain network, the UE can quickly transmit voice data with the opposite terminal through the forwarding channel without waiting for the completion of the domain switching procedure for a long time, thereby ensuring good voice service continuity in the reverse SRVCC switching process, further, the forwarding channel is established on the basis that the UE completes the PS domain network access, therefore, the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 11 is a schematic structural diagram of a second embodiment of a user terminal according to the present invention. Specifically, in this embodiment, the first network element in the PS domain network may specifically be a PGW or an ATGW, and the second network element in the CS domain network may specifically be an rSRVCC MSC.

As shown in fig. 11, on the basis of the previous embodiment, in the user terminal of this embodiment, optionally, the resource information configuring module may specifically include: IMS registration section 111 and SIP session establishment section 112. The IMS registration unit 111 is configured to perform IMS registration in the PS domain network before the user terminal switches the voice service from the CS domain network to the PS domain network; and the SIP session establishing unit 112 is configured to establish a SIP session in the PS domain network before the user terminal switches the voice service from the CS domain network to the PS domain network.

Specifically, the SIP session establishing unit 112 may further include a first indicating sub-unit 1121, where the first indicating sub-unit 1121 is configured to send rSRVCC indicating information to the SCC AS in an SIP session establishing process performed by the SIP session establishing module 112, where the rSRVCC indicating information is used to indicate that the SCC AS establishes an SIP session at this time for a reverse SRVCC service handover, so that the SCC AS does not need to initiate a voice call to an opposite terminal user equipment, and does not actively trigger a release procedure of pre-configured resource information.

Further optionally, in the user terminal of this embodiment, the IMS registration unit 111 may further include a second indication subunit 1111, where the second indication subunit 111 is configured to send, in an IMS registration procedure performed by the IMS registration module 111, indication information to the SGSN, where the indication information is used to indicate that the SGSN does not initiate an RAB establishment procedure before the user terminal initiates handover of a voice service from a CS domain network to a PS domain network.

Further, in this embodiment, the user terminal may further include a VOIP voice bearer establishing module 12. The VOIP voice bearer establishing module 12 is configured to, after the SIP session establishing unit 112 performs the above SIP session establishing process, before the user terminal initiates the switching of the voice service from the CS domain network to the PS domain network, establish a reserved VOIP voice bearer for the voice service switching in the PS domain network in advance; or, the VOIP voice bearer establishing module 12 is configured to establish a VOIP voice bearer for switching the voice service in the PS domain network after the user terminal initiates the switching of the voice service from the CS domain network to the PS domain network.

The user terminal of this embodiment, before switching the voice service from the CS domain network to the PS domain network, performs IMS registration in the PS domain network in advance to make the PS domain network pre-allocate bearer resources for the UE, so that in the process of switching the voice service from the CS domain network to the PS domain network, the PS domain network pre-allocates bearer information for the UE, and a forwarding channel can be established between the CS domain network and the PS network, so that after the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and quickly accesses to the PS domain network, the UE can quickly transmit voice data to the opposite terminal through the forwarding channel without waiting for the completion of a long domain switching procedure, thereby ensuring good voice service continuity in the reverse vcc srswitching process, further, the forwarding channel is established on the basis that the UE completes the PS domain network access, therefore, the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 12 is a schematic structural diagram of a mobility management entity according to a first embodiment of the present invention. As shown in fig. 12, the mobility management entity of this embodiment at least includes two modules, a receiving module 21 and a forwarding path establishing module 22. The receiving module 21 is configured to receive a handover request, where the handover request is used to request that a voice service of a UE is handed over from a CS domain network to a PS domain network; the forwarding channel establishing module 22 is configured to, in a process that the UE switches the voice service from the CS domain network to the PS domain network, control, by using resource information required for switching the voice service, which is configured in the PS domain network in advance by the UE, to establish a forwarding channel between a first network element of the PS domain network and a second network element of the CS domain network. Specifically, the forwarding path establishing module 22 controls the established forwarding path to be used for: and after the UE is accessed to the PS domain network, forwarding voice service data between the UE and the opposite UE.

The mobility management entity of the embodiment, by means of the process of the UE switching the voice service from the CS domain network to the PS domain network, the UE is utilized to control and establish a forwarding channel between the CS domain network and the PS domain network of voice data through the resource information configured in the PS domain network in advance before switching the voice service from the CS domain network to the PS domain network, therefore, when the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and quickly accesses to the PS domain network, the UE can quickly transmit voice data with the opposite terminal through the forwarding channel, without waiting for the completion of the domain switching process for a long time, the method ensures good voice service continuity in the reverse SRVCC switching process, and further, the forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 13 is a schematic structural diagram of a second embodiment of a mobility management entity according to the present invention. Specifically, in this embodiment, the first network element in the PS domain network may specifically be an ATGW or a PGW, and the second network element in the CS domain network may specifically be an rSRVCC MSC. The UE establishes a flow through an IMS registration flow and an SIP session, and the resource information configured in the PS domain network in advance may at least include context information that the UE registers in the PS domain network in advance, where the context information at least includes STN-SR information.

On this basis, when the first network element is an ATGW and the UE supports the DTM or UMTS mode, the forwarding channel establishing module 22 may further include two sub-units, namely, a request receiving unit 221 and an information forwarding unit 222. Wherein, the request receiving unit 221 is configured to receive a handover request forwarded by an SGSN, where the handover request carries the context information pre-registered by the UE; the information forwarding unit 222 is configured to forward the context information to the rSRVCC MSC, so that the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information of the UE, and establishes a forwarding channel with the corresponding ATGW.

Further, when the first network element is an ATGW and the UE does not support the DTM or UMTS mode, the forwarding channel establishing module 22 may further include: three subunits of an identification inquiry unit 223, an information acquisition unit 224 and a request response unit 225. Specifically, the identifier querying unit 223 is configured to query, in the HSS, an identifier of an SGSN corresponding to the UE according to the received handover request forwarded by the rSRVCC MSC; the information acquiring unit 224 is configured to acquire the context information pre-registered by the UE from the specified SGSN according to the identifier of the SGSN queried by the identifier querying unit 223; and the request response unit 225 is configured to carry STN-SR information in the context information acquired by the information acquisition unit 224 in a handover response message and return the handover response message to the rSRVCC MSC, so that the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information and establishes a forwarding channel with the corresponding ATGW.

Further, when the first network element is a PGW, in this embodiment, the forwarding channel establishing module 22 may further include an information obtaining and forwarding unit 226. The information obtaining and forwarding unit 226 is configured to obtain addresses and/or port information allocated to the UE by the PGW and the rSRVCC MSC from the PGW and the rSRVCC MSC, respectively, and interact the obtained addresses and/or port information between the PGW and the rSRVCC MSC, so as to establish a forwarding channel between the PGW and the rSRVCC MSC.

Specifically, the specific working processes related to all the modules in this embodiment may also refer to the related contents disclosed in the related embodiments related to the above processing method for reverse single wireless voice call continuity, and are not described herein again.

The mobility management entity of the embodiment, by means of the process of the UE switching the voice service from the CS domain network to the PS domain network, controlling the forwarding channel between the CS domain network and the PS network for establishing voice data by using the resource information configured by the IMS registration performed in the PS domain network in advance before the voice service is switched from the CS domain network to the PS domain network by the UE, therefore, when the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and quickly accesses to the PS domain network, the UE can quickly transmit voice data with the opposite terminal through the forwarding channel, without waiting for the completion of the domain switching process for a long time, the method ensures good voice service continuity in the reverse SRVCC switching process, and further, the forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Fig. 14 is a block diagram of an embodiment of a reverse single wireless voice call continuity processing system according to the invention. As shown in fig. 14, the processing system for reverse voice call continuity service of this embodiment at least includes a user terminal 1, a first network element 2 and a second network element 3.

Specifically, the user terminal 1 is configured to pre-configure resource information in the PS domain network before switching the voice service from the CS domain network to the PS domain network; the first network element 2 is located in a PS domain network, the second network element 3 is located in a CS domain network, and the first network element 2 may specifically be a PGW or ATGW device in the PS domain network, and the second network element 3 may specifically be an rSRVCC MSC device in the CS domain network. In the process that the user terminal 1 switches the voice service from the CS domain network to the PS domain network, by using the resource information pre-configured by the user terminal 1, a forwarding channel can be established between the first network element 2 and the second network element 3, and the forwarding channel is used for forwarding the voice service data between the user terminal 1 and the opposite terminal user terminal after the user terminal 1 is accessed to the PS domain network.

Specifically, all modules included in the ue in this embodiment and the specific working processes related to the included modules may refer to the related contents disclosed in the related embodiments related to the single radio reverse voice call continuity processing method, the ue and the mobility management entity, which are not described herein again.

In the processing system for continuity of reverse single wireless voice call of this embodiment, before the UE switches the voice service from the CS domain network to the PS domain network, the UE performs IMS registration in the PS domain network in advance and initiates establishment of an SIP session, so that the PS domain network allocates bearer resource information to the UE in advance, and in the process of switching the voice service from the CS domain network to the PS domain network, the PS domain network allocates the reserved bearer information to the UE in advance, and establishes a forwarding channel between the CS domain network and the PS network for voice data, so that after the UE really initiates the switching of the voice service from the CS domain network to the PS domain network and rapidly accesses to the PS domain network, the UE can rapidly transmit voice data with an opposite terminal through the established forwarding channel without waiting for completion of a long-time domain switching procedure, thereby ensuring good voice service continuity in the reverse SRVCC switching process, furthermore, the established forwarding channel is established on the basis that the UE completes the PS domain network access, so that the voice service based on the forwarding channel can also obtain good voice service quality.

Further, on the basis of the above technical solution, the processing system of the reverse voice call continuity service according to this embodiment may further include a mobile management entity 4. The mobility management entity 4 is configured to, in a process that the user terminal 1 switches the voice service from the CS domain network to the PS domain network, control the forwarding channel to be established between the first network element 2 and the second network element 3 by using resource information pre-configured by the user terminal 1. Specifically, all modules included in the mobility management entity in this embodiment and the specific working processes related to the included modules may also refer to the related contents disclosed in the related embodiments related to the reverse single wireless voice call continuity processing method, the user terminal and the mobility management entity, which are not described herein again.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A method for processing reverse single wireless voice call continuity, comprising:

2. The method of claim 1, wherein the reverse single wireless voice call continuity processing method comprises:

the first network element is a domain switching gateway ATGW or a packet data network gateway PGW, and the second network element is a mobile switching center rSRVCCMSC supporting a reverse single wireless voice call continuity service.

3. The method of claim 2, wherein the establishing a forwarding path between the first network element of the packet-switched domain and the second network element of the circuit domain using the pre-configured resource information specifically comprises:

and the MME controls the establishment of the forwarding channel between the first network element of the packet switching domain and the second network element of the circuit domain by utilizing the pre-configured resource information.

4. The method of claim 3, wherein the reverse single wireless voice call continuity processing method comprises:

the resource information at least comprises context information registered in the packet switched domain network by the user terminal in advance, and the context information at least comprises session transfer number STN-SR information used for reverse voice call continuity service;

if the first network element is the ATGW and the user terminal supports a dual mode transmission DTM or a universal mobile telecommunications system UMTS mode, the controlling, by the MME, the establishment of the forwarding channel between the first network element of the packet switching domain and the second network element of the circuit domain by using the pre-configured resource information specifically includes:

the MME receives a switching request forwarded by a serving GPRS support node, wherein the switching request carries the context information pre-registered by the user terminal;

and the MME forwards the context information to the rSRVCC MSC so that the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information in the context information and establishes the forwarding channel with the corresponding ATGW.

5. The method of claim 3, wherein the reverse single wireless voice call continuity processing method comprises:

the resource information at least comprises context information registered in the packet switched domain network by the user terminal in advance, and the context information at least comprises STN-SR information;

if the first network element is the ATGW and the user terminal does not support the DTM or UMTS mode, the controlling, by the MME, the establishment of the forwarding channel between the first network element of the packet switching domain and the second network element of the circuit domain by using the pre-configured resource information specifically includes:

the MME inquires the identification of a serving GPRS support node corresponding to the user terminal in a Home Subscriber Server (HSS) according to the received switching request forwarded by the rSRVCC MSC;

the MME acquires the context information pre-registered by the user terminal from a designated serving GPRS support node according to the inquired identification of the serving GPRS support node;

and the MME carries the STN-SR information in the context information in a switching response message and returns the switching response message to the rSRVCC MSC so that the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information in the context information and establishes the forwarding channel with the corresponding ATGW.

6. The method of claim 2, wherein the reverse single wireless voice call continuity processing method comprises:

if the first network element is the ATGW and the user terminal does not support the DTM or UMTS mode, the establishing a forwarding channel between the first network element of the packet switched domain and the second network element of the circuit domain by using the pre-configured resource information specifically includes:

after receiving the switching request, the rSRVCC MSC inquires the identification of a service GPRS supporting node corresponding to the user terminal in the HSS;

the rSRVCC MSC forwards the switching request to MME through a designated serving GPRS support node according to the inquired identification of the serving GPRS support node, and obtains the context information registered in advance by the user terminal from the designated serving GPRS support node;

and the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information in the context information, and establishes the forwarding channel with the corresponding ATGW.

7. The method of claim 3, wherein if the first network element is the PGW, the MME controlling, by using the pre-configured resource information, establishment of the forwarding path between the first network element in the packet switching domain and the second network element in the circuit domain specifically includes:

the MME acquires addresses and/or port information allocated to the user terminal by the PGW and the rSRVCC MSC from the PGW and the rSRVCC MSC respectively, and interacts the acquired addresses and/or port information between the PGW and the rSRVCC MSC so as to establish the forwarding channel between the PGW and the rSRVCC MSC.

8. The method for processing continuity of a reverse single radio voice call according to any of claims 1 to 7, wherein, before the user terminal switches the voice service from the circuit domain network to the packet switched domain network, pre-configuring resource information required for switching the voice service in the packet switched domain network specifically includes:

before switching the voice service from the circuit domain network to the packet switched domain network, the user terminal performs IMS registration and SIP session establishment in the packet switched domain network so as to pre-configure the resource information in the packet switched domain network.

9. The method of claim 8, wherein the method further comprises:

the user terminal sends reverse single wireless voice call continuity (rSRVCC) indication information to a service centralization and continuous application server (SCC AS) in the SIP session establishment process, wherein the rSRVCC indication information is used for indicating the SCC AS that the SIP session is used in reverse voice call continuity service switching, so that the SCC AS does not need to initiate a voice call to the opposite terminal user terminal and does not actively trigger the release flow of the pre-configured resource information.

10. The method of claim 8, wherein the method further comprises:

and the user terminal sends indication information to a serving GPRS support node in the IMS registration process, wherein the indication information is used for indicating that the serving GPRS support node does not initiate the establishment process of the radio access bearer before the user terminal initiates the switching of the voice service from the circuit domain network to the packet switching domain network.

11. The method of claim 8, wherein the method further comprises:

after the establishment process of the SIP session, the user terminal establishes a reserved VOIP voice bearer for voice service switching in the packet switched domain network in advance before switching the voice service from the circuit domain network to the packet switched domain network;

or after the user terminal initiates the switching of the voice service from the circuit domain network to the packet switched domain network, establishing a VOIP voice bearer for the voice service switching in the packet switched domain network.

12. A user terminal, comprising:

13. The user terminal of claim 12, wherein:

14. The ue according to claim 12 or 13, wherein the resource information configuring module specifically includes:

an IMS registration unit, configured to perform IMS registration in a packet switched domain network before the user terminal switches a voice service from a circuit domain network to the packet switched domain network;

and the SIP session establishing unit is used for establishing the SIP session in the packet switched domain network before the user terminal switches the voice service from the circuit domain network to the packet switched domain network.

15. The user terminal according to claim 14, wherein the SIP session establishing unit comprises at least:

a first indicating subunit, configured to send, to a service centralized and continuous application server SCC AS, indication information of reverse single wireless voice call continuity rSRVCC during the SIP session establishment process, where the rSRVCC indication information is used to indicate the SCC AS that the SIP session is used in a reverse voice call continuity service handover, so that the SCC AS does not need to initiate a voice call to the opposite-end user terminal and does not actively trigger a release procedure of the pre-configured resource information.

16. The ue of claim 14, wherein the IMS registration unit comprises at least:

a second indicating subunit, configured to send, in the IMS registration procedure, indication information to a serving GPRS support node, where the indication information is used to indicate that the serving GPRS support node does not initiate a procedure for establishing a radio access bearer before the user equipment initiates a handover of a voice service from a circuit domain network to a packet switched domain network.

17. The user terminal according to claim 14, further comprising:

a VOIP voice bearer establishing module, configured to establish a reserved VOIP voice bearer for voice service switching in the packet-switched domain network in advance before the user terminal initiates switching of a voice service from a circuit domain network to a packet-switched domain network after the SIP session establishing unit establishes the SIP session; or after the user terminal initiates the switching of the voice service from the circuit domain network to the packet switched domain network, establishing a VOIP voice bearer for the voice service switching in the packet switched domain network.

18. A mobility management entity, comprising:

a forwarding channel establishing module, configured to, according to the switching request, control, by using resource information, which is required by the user terminal to switch the voice service from the circuit switched domain network to the packet switched domain network and is configured in the packet switched domain network in advance, a forwarding channel to be established between a first network element of the packet switched domain network and a second network element of the circuit switched domain network, where the forwarding channel is used to forward voice service data between the user terminal and an opposite-end user terminal after the user terminal is accessed to the packet switched domain network.

19. The mobility management entity according to claim 18, wherein:

20. The mobility management entity according to claim 19, wherein:

if the first network element is the ATGW and the user terminal supports a dual mode transmission DTM or a universal mobile telecommunications system UMTS mode, the forwarding channel establishing module specifically includes:

a request receiving unit, configured to receive the handover request forwarded by a serving GPRS support node, where the handover request carries the context information pre-registered by the user equipment;

and the information forwarding unit is used for forwarding the context information to the rSRVCC MSC so that the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information in the context information and establishes the forwarding channel with the corresponding ATGW.

21. The mobility management entity according to claim 19, wherein:

if the first network element is the ATGW and the user terminal does not support the DTM or UMTS mode, the forwarding channel establishing module specifically includes:

an identifier query unit, configured to query, in a home subscriber server HSS, an identifier of a serving GPRS support node corresponding to the user terminal according to the received handover request forwarded by the rSRVCC MSC;

an information obtaining unit, configured to obtain, from an appointed serving GPRS support node, the context information pre-registered by the user equipment according to the queried identifier of the serving GPRS support node;

and the request response unit is used for carrying the STN-SR information in the context information in a switching response message and returning the switching response message to the rSRVCC MSC so that the rSRVCC MSC addresses the corresponding ATGW according to the STN-SR information and establishes the forwarding channel with the corresponding ATGW.

22. The mme of claim 19, wherein if the first network element is the PGW, the forwarding path establishment module further comprises:

an information obtaining and forwarding unit, configured to obtain, from the PGW and the rSRVCC MSC, addresses and/or port information allocated to the user terminal by the PGW and the rSRVCC MSC, respectively, and interact the obtained addresses and/or port information between the PGW and the rSRVCC MSC, so as to establish the forwarding channel between the PGW and the rSRVCC MSC.

23. A system for processing reverse single wireless voice call continuity, comprising: the system comprises a user terminal, a first network element and a second network element; wherein,

the user terminal is used for pre-configuring resource information required by voice service switching in the packet switched domain network before switching the voice service from the circuit domain network to the packet switched domain network;

24. The reverse single wireless voice call continuity handling system according to claim 23, wherein:

25. The reverse single wireless voice call continuity processing system according to claim 23 or 24, further comprising:

and the mobile management entity is used for controlling the establishment of the forwarding channel between the first network element of the packet switching domain and the second network element of the circuit domain by utilizing the pre-configured resource information in the process of switching the voice service from the circuit domain network to the packet switching domain network by the user terminal.