CN113875287B

CN113875287B - IMS voice communication method, wireless communication device and communication system

Info

Publication number: CN113875287B
Application number: CN201980096887.XA
Authority: CN
Inventors: 姚琴波; 胡文; 夏苗方; 闫志吉
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-08-06
Filing date: 2019-08-06
Publication date: 2023-04-04
Anticipated expiration: 2039-08-06
Also published as: CN113875287A; WO2021022497A1

Abstract

The application discloses an internet protocol multimedia subsystem IMS voice communication method, a wireless communication device and a communication system, wherein the method comprises the following steps: receiving an EPS (evolved packet System) fallback indication message; switching from first access network equipment supporting a fifth generation mobile communication network to second access network equipment supporting a fourth generation mobile communication network to perform IMS voice communication; and after the IMS voice communication is finished, accessing to the fifth generation mobile communication network when a wireless resource control connection release message is received, wherein the wireless resource control connection release message does not carry redirection carrier information. And after receiving the EPS fallback indication message, the terminal falls back to the fourth generation mobile communication network from the fifth generation mobile communication network, autonomously identifies the scene needing autonomous returning, and autonomously returns to the fifth generation mobile communication network in the scene needing autonomous returning.

Description

IMS voice communication method, wireless communication device and communication system

Technical Field

The present application relates to the field of communications technologies, and in particular, to an IMS voice communication method, a wireless communication apparatus, and a communication system.

Background

An Evolved Packet System Fallback (EPS Fallback) may occur during the communication process of the terminal in the fifth-generation mobile communication network, that is, the terminal falls back from the fifth-generation mobile communication network to the fourth-generation mobile communication network. After the fall back has occurred, the terminal may return to the fifth generation mobile communication network where it was before the fall back by redirection of the access network device of the fourth generation mobile communication network.

However, currently, the access network device of the fourth generation mobile communication network does not have the above redirection function, and only after the upgrade, the redirection of the terminal falling back to the fourth generation mobile communication network to the fifth generation mobile communication network is supported. Upgrading access network equipment is often not recommended at present, because the access network equipment is subjected to a plurality of problems. Several problems will be briefly enumerated below: firstly, the air interface of the access network equipment needs to be modified for upgrading, so that the access network equipment supports the redirection function, but the modification of the air interface is not only complicated, but also errors are easy to occur, and the system is not compatible; secondly, for some old versions of access network equipment, not only the redirection function needs to be upgraded, but also other functions in the access network equipment need to be upgraded in advance before the redirection function is upgraded; second, since the upgrade may limit the communication traffic and even completely disconnect the communication service, the upgrade of the access network equipment is generally performed late at night when the traffic is low in order to minimize the impact on the normal communications of the user. It can be seen that access network equipment upgrade is not only costly, but also difficult.

Disclosure of Invention

The embodiment of the application provides an internet protocol Multimedia Subsystem (IMS, IP Multimedia Subsystem) voice communication method, so that a terminal can autonomously return to a fifth-generation mobile communication network after an Evolved Packet System Fallback (EPS Fallback, or Evolved Packet System Fallback).

It should be understood that the method in the embodiment of the present application may be executed by a wireless communication apparatus, which may be a complete computer of a computing device, or may be a part of a device in the computing device, for example, a chip related to a wireless communication function, such as a system chip, a communication chip, or a radio frequency chip. The system chip is also called a system on chip, or SoC chip. Specifically, the wireless communication apparatus may be a terminal such as a smartphone, and may also be a system chip or a communication chip that can be provided in the terminal. The communication chip may include one or more of a radio frequency processing chip and a baseband processing chip. The baseband processing chip is sometimes also referred to as a modem (modem) or baseband processor. In physical implementation, the communication chip may be integrated inside the SoC chip or may not be integrated with the SoC chip. For example, the baseband processing chip is integrated in the SoC chip, and the radio frequency processing chip is not integrated with the SoC chip.

In a first aspect, an embodiment of the present application provides an IMS voice communication method, where after receiving an Evolved Packet System (EPS) fallback indication message sent by a first access network device, a wireless communication device, in response to the EPS fallback indication message, drops from a fifth-generation mobile communication network to a fourth-generation mobile communication network, that is, switches from a first access network device of the fifth-generation mobile communication network to a second access network device of the fourth-generation mobile communication network; then, after connecting to the second access network device, the wireless communication device performs an internet protocol Multimedia Subsystem (IMS) voice communication through the fourth generation mobile communication network; the wireless communication apparatus accesses the first access network device or the third access network device of the fifth generation mobile communication network upon receiving a radio resource control connection release (RRCConnectionRelease) message after ending the IMS voice communication, where the radio resource control connection release message does not carry redirection carrier information (redirectedCarrierInfo). The EPS fallback indication message is a mobility message (MobilityFromNRCommand) message from a new radio command, or a radio resource control release (RRCRelease) message. The third access network device is any access network device except the second access network device in the fifth generation mobile communication network.

It should be understood that the wireless communication apparatus ending the IMS voice communication means that the wireless communication apparatus transmits a BYE message and receives a good 200 (OK) message while performing the IMS calling service, or the wireless communication apparatus receives a BYE message and transmits a good 200 (OK) message in response to the BYE message while performing the IMS called service. The BYE message and the good 200 (OK) message are messages in a Session Initiation Protocol (SIP), specifically, the BYE message is used to indicate that the IMS voice communication is ended, and the good 200 (OK) message is used to respond to the BYE message.

Based on the method described in the first aspect, the wireless communication device may autonomously identify whether the current scenario is a scenario requiring autonomous return after the fallback, and initiate autonomous return in the scenario requiring autonomous return, and reduce invalid autonomous return attempts in the scenario not requiring autonomous return. Therefore, by the method of the embodiment of the application, the wireless communication device can avoid staying in the fourth generation mobile communication network under the condition that the access network equipment supporting the fourth generation mobile communication network is not upgraded, autonomously return to the fifth generation mobile communication and obtain better communication experience.

In an implementable manner, after the wireless communication device finishes IMS voice communication, when a rrc connection release message not carrying redirection carrier information is received and a Quality of Service Flow (QoS Flow) of the IMS voice does not exist before the EPS fallback indication message is received, the wireless communication device accesses the fifth-generation mobile communication network. Based on such an embodiment, the wireless communication apparatus can more accurately identify whether the current scenario is a scenario that requires autonomous return by further determining whether the fallback is caused because the fifth generation mobile communication network does not support IMS voice communication.

In an implementable manner, after the wireless communication device finishes IMS voice communication, when a rrc connection release message not carrying redirection carrier information is received and a measurement report is not reported within a preset time period before the EPS fallback indication message is received, the wireless communication device accesses the fifth-generation mobile communication network.

The preset duration is a specific duration set in advance, where the measurement report may be a common measurement report, or may refer to a measurement report including a specific handover event. The measurement report may represent the communication quality of the wireless communication device. Wherein, the specific switching event comprises one or two of a B1 event and a B2 event. The B1 event is used to indicate that the quality of the inter-system cell is better than the threshold, the B2 event is used to indicate that the quality of the serving cell where the wireless communication device is located is lower than the threshold 1, and the quality of the inter-system cell is better than the threshold 2. Based on such an embodiment, the wireless communication device can more accurately identify whether the current scenario is a scenario that requires autonomous return by quickly determining that the EPS fallback is not caused by the poor communication quality of the wireless communication device in the fifth generation mobile communication network.

In a second aspect, a wireless communication apparatus is provided, which may be a terminal device or an apparatus for a terminal device. For example, the terminal device may be a mobile phone, a wearable device, a tablet computer, or the like. The means for the terminal device may be a chip within the terminal device. The wireless communication device may perform the method as described in any one of the first aspect and the possible implementation manners of the first aspect. The functions of the wireless communication device may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more units corresponding to the above functions. The unit may be software and/or hardware. The wireless communication apparatus includes:

a receiving unit, configured to receive an EPS fallback indication message; the processing unit is used for switching from first access network equipment supporting a fifth generation mobile communication network to second access network equipment supporting a fourth generation mobile communication network to carry out Internet protocol multimedia subsystem (IMS) voice communication; the receiving unit is further configured to receive a radio resource control connection release message (RRCConnectionRelease), where the radio resource control connection release message does not carry redirection indication information (redirectedCarrierInfo); the processing unit is configured to access the fifth-generation mobile communication network when receiving a radio resource control connection release message after the IMS voice communication is completed. The EPS fallback indication message is a mobility message (MobilityFromNRCommand) from a new radio command or a radio resource control release (rrcreelease) message. The third access network device is any access network device except the second access network device in the fifth generation mobile communication network.

In an implementation manner, the processing unit is specifically configured to: after the BYE message is sent and the good OK message is received, or after the BYE message is received and the good OK message is sent, when the radio resource control connection release message is received, the fifth generation mobile communication network is accessed; the BYE message and the OK message are messages in a session initiation protocol, the BYE message is used for indicating the end of the IMS voice communication, and the OK message is used for responding to the BYE message.

In an implementation manner, the processing unit is specifically configured to: and after the IMS voice communication is finished, accessing to the fifth generation mobile communication network when a radio resource control connection release message which does not carry redirection carrier information is received and the quality of service flow of the IMS voice does not exist before the EPS fallback indication message of the evolved packet system is received.

In an implementation manner, the processing unit is specifically configured to: and after the IMS voice communication is finished, accessing to the fifth generation mobile communication network when a radio resource control connection release message which does not carry redirection carrier information is received and a measurement report is not reported within a preset time before the EPS fallback indication message of the evolved packet system is received. The measurement report may be a general measurement report, and may also specifically refer to a measurement report including a B1 event, or a B2 event, or a B1 event and a B2 event.

In a third aspect, a wireless communication apparatus is provided, which may be a terminal device or an apparatus for a terminal device. For example, the terminal device may be a mobile phone, a wearable device, a tablet computer, or the like. The means for the terminal device may be a chip within the terminal device. The wireless communication device includes a processor and a transceiver. Wherein the processor is connected to the transceiver. Optionally, the wireless communication device further comprises a memory. A processor is coupled to the memory.

In an implementable manner, when the wireless communication device is a terminal device, the transceiver may include an antenna and a radio frequency circuit connected to the antenna. The transceiver is used for realizing communication between the wireless communication device and other network elements. For example, the transceiver is used to enable communication between the wireless communication device and a network device.

In an implementation manner, when the wireless communication device is a device for a terminal device, the transceiver may be an interface circuit, and the interface circuit is used for the processor to acquire or output information or data. For example, the interface circuit is used for the processor to read data from or write data to the memory, and for example, the interface circuit is used for the processor to receive information or data from or transmit information or data to the outside of the device.

Wherein the processor is configured to perform the method of any one of the first aspect and the implementable modes of the first aspect.

Wherein the memory is used for storing a program, and the processor calls the program stored in the memory to execute the method of any one of the first aspect and the implementable embodiments of the first aspect. The operations and advantages performed by the processor may refer to the method and advantages described in any one of the first aspect and the implementable modes of the first aspect, and repeated descriptions are omitted here.

In a fourth aspect, a communication system is provided. The communication system includes a wireless communication device and a first access network apparatus, wherein: the first access network device is configured to send an EPS fallback indication message to the wireless communication apparatus; the wireless communication device is configured to receive an EPS fallback indication message sent by the first access network device, and then switch from a first access network device supporting a fifth-generation mobile communication network to a second access network device supporting a fourth-generation mobile communication network, to perform IMS voice communication; the wireless communication device is further configured to access the fifth-generation mobile communication network after the IMS voice communication is terminated and when a radio resource control connection release message (RRCConnectionRelease) is received, where the radio resource control connection release message does not carry redirection carrier information (redirectedCarrierInfo). The EPS fallback indication message is a mobility message (MobilityFromNRCommand) message from a new radio command, or a radio resource control release (RRCRelease) message. The third access network device is any access network device except the second access network device in the fifth generation mobile communication network.

In one implementation, the terminating of the IMS voice communication by the wireless communication apparatus means that after sending a BYE-BYE message and receiving a good OK message, or after receiving a BYE-BYE message and sending a good OK message, the BYE message and the OK message are messages in a session initiation protocol, the BYE message indicates that the IMS voice communication is terminated, and the OK message is used to respond to the BYE message.

In an implementable manner, the wireless communication device is specifically configured to, after the IMS voice communication is ended, access to the fifth-generation mobile communication network when a rrc connection release message that does not carry information of a redirection carrier is received and a qos flow of the IMS voice does not exist before the EPS fallback indication message is received.

In an implementable manner, the wireless communication device is specifically configured to, after the IMS voice communication is ended, access to the fifth generation mobile communication network when a rrc connection release message that does not carry information of a redirection carrier is received and a measurement report is not reported within a preset time period before the EPS fallback indication message of the evolved packet system is received. The measurement report may be a general measurement report, and may also specifically refer to a measurement report including a B1 event, or a B2 event, or a B1 event and a B2 event.

In a fifth aspect, a computer program product is provided, which, when run on a computer, causes the computer to perform the method of the first aspect or possible implementation manner of the first aspect.

A sixth aspect provides a computer-readable storage medium having stored therein instructions which, when run on a computer, cause the computer to perform the above first aspect or the method of an implementable embodiment of the first aspect.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below.

Fig. 1 is a schematic architecture diagram of a communication system according to an embodiment of the present application;

fig. 2 is a flowchart illustrating an IMS voice communication method according to an embodiment of the present application;

fig. 3 is a flowchart illustrating another IMS voice communication method according to an embodiment of the present application;

fig. 4 is a flowchart illustrating an IMS voice communication method according to an embodiment of the present application;

fig. 5 is a schematic block diagram of a wireless communication device provided by an embodiment of the present application;

fig. 6 is a block diagram illustrating a structure of a wireless communication apparatus according to an embodiment of the present disclosure.

Detailed Description

The embodiment of the application provides an IMS voice communication method, a wireless communication device and a communication system. Wherein the IMS voice communication method may be performed by a wireless communication device. The wireless communication apparatus may be a terminal, or may be an apparatus for a terminal device. The means for the terminal device may be a chip or the like within the terminal device. The IMS voice communication method will be described below with a terminal as an execution subject. By implementing the method of the embodiment of the application, the terminal can autonomously identify the scene needing autonomous return and trigger the return to the 5G mobile communication network after the terminal falls back to the fourth generation (4G, 4th generation) mobile communication network from the fifth generation (5G, 5th generation) mobile communication network, and does not need the access network equipment of the 4G mobile communication network to instruct the terminal to redirect to the 5G mobile communication network.

The following describes an architecture of a communication system to which embodiments of the present application are applicable. As shown in the architecture of the communication system in fig. 1, the communication system comprises a terminal, a first access network device and a second access network device. The first access network device is a next generation Node B (gNodeB or gNB); the second access network device is an evolved Node B (eNodeB or eNB). Optionally, the communication system may further include other access network devices (e.g., a third access network device) and a terminal, where the third access network device is also a gNB, and the first access network device, the second access network device, and the third access network device are different devices, which is not described herein again.

A terminal may also be referred to as a User Equipment (UE), a Mobile Station (MS), or a Subscriber Unit (SU), among others. The terminal may specifically be, but not limited to, a mobile phone, a tablet computer (tablet computer), a laptop computer (laptop computer), a wearable device (smart watch, smart bracelet, smart helmet, smart glasses, etc.), and other communication devices with wireless access capability, such as various internet of things devices including smart home devices (smart meter, smart home appliance, etc.), a smart vehicle, and the like.

The access network device may provide communication coverage for a specific geographic area, and may communicate with a terminal located in the coverage area, and the access network device may support communication protocols of different systems, or may support different communication modes.

The terminal can access to the corresponding mobile communication network through the access network device, here, the first access network device supports a 5G mobile communication network, and the second access network device supports a 4G mobile communication network as an example. In general, the communication effect and service experience obtained from the 5G mobile communication network may be better than those of the 4G mobile communication network, but in a few cases such as unstable communication environment, the communication effect of the 4G mobile communication network may actually be better than that of the 5G mobile communication network. Therefore, when the terminal performs communication, the terminal is preferably accessed to the 5G mobile communication network, and the terminal will fall back from the 5G mobile communication network to the 4G mobile communication network only when the communication quality of the terminal in the 5G mobile communication network is poor or the 5G mobile communication network does not support IMS voice communication that the terminal needs to perform. The IMS voice communication includes a general voice call (voice call) service, an emergency call (emergency call) service, a video call (video call) service, and the like.

In summary, during the process that the terminal maintains the connection state with the first access network device supporting the 5G mobile communication network, the terminal may be handed over from the first access network device under the 5G mobile communication network to the second access network device under the 4G mobile communication network, so that an Evolved Packet System Fallback (EPS Fallback, or Evolved Packet System Fallback) occurs, where the Evolved Packet System Fallback falls back from the 5G mobile communication network to the 4G mobile communication network. Since the communication effect of the 5G mobile communication network is superior to that of the 4G mobile communication network in most cases, even if a fallback occurs, the terminal wants to return to the 5G mobile communication network as soon as possible to obtain a higher quality communication service.

In this case, the terminal may be instructed to return to the 5G mobile communication network where the terminal was located before the fallback in a manner of redirection by the access network device. However, it is a real situation that an access network device under the 4G mobile communication network needs to be upgraded to support redirection of the terminal to the 5G mobile communication network.

In order to solve the above problem, the present application provides an IMS voice communication method, which can implement autonomous return of a terminal without returning under the instruction of an access network device in a 4G mobile communication network. Specifically, the terminal receives an Evolved Packet System (EPS) fallback indication message sent by a first access network device of the 5G mobile communication network. And then the terminal falls back to the 4G mobile communication network from the 5G mobile communication network according to the EPS falling indication message, namely, the terminal is switched to a second access network device under the 4G mobile communication network from a first access network device under the 5G mobile communication network. After the terminal falls back successfully, IMS voice communication is carried out through the 4G mobile communication network. And finally, the terminal accesses to the 5G mobile communication network when the IMS voice communication is completed and the radio resource control connection release message which does not carry the redirection carrier information is received.

In order to better understand the IMS voice communication method provided in the present application, the present application will be described in more detail. For example, when the first access device and the terminal are in a connection state, the first access device sends an EPS fallback indication message to the terminal to indicate that the terminal is switched from the first access device in the 5G mobile communication network to the second access device in the 4G mobile communication network. The fallback indication message may be a mobility fromnrcommm (mobility command) message from a new radio command described in the third generation partnership project (3 gpp,3rd generation partnership project) technical specification, or may be a radio resource control release (rrcelease) message. And after receiving the fallback indication message, the terminal is connected to the second access equipment according to the fallback indication message to fall back to the 4G to execute IMS voice communication. Since the IMS voice communication is performed after the terminal falls back, it can be determined that the fall back is caused by the fact that the 5G mobile communication network does not support IMS voice communication, and is not caused by the fact that the communication quality of the terminal in the 5G mobile communication network is poor. Therefore, after the IMS voice communication is completed, if it is identified that the current scenario is a scenario that needs to be returned autonomously, that is, when a radio resource control connection release (RRCConnectionRelease) message that does not carry a redirect carrier information (redirect _ carrier _ info) field is received, the mobile communication device autonomously accesses the 5G mobile communication network.

It should be noted that the terminal of the present application autonomously returns to the 5G mobile communication network, and does not need to access to the 5G mobile communication network according to the instruction of the access network device. It can be understood that there are various types of rrc connection release messages sent by the network side, and the terminal may determine, according to whether the received rrc connection release message includes a redirection carrier information field and information carried in the redirection carrier information field, to which system or which frequency cell the terminal is redirected after receiving the rrc connection release message.

Specifically, according to the 3GPP ts36.331 technical specification (for example, the 3GPP ts36.331 v15.4.0 technical specification), in the prior art, when the radio resource control connection release message received by the wireless communication network does not carry the redirection carrier information, the wireless communication network enters an IDLE (IDLE) state according to the specification of the 3GPP technical specification, and then autonomously initiates an access procedure to the 5G mobile communication network; when the radio resource control connection release message received by the wireless communication network carries the redirection carrier information, the wireless communication network accesses the mobile communication network pointed by the redirection carrier information carried by the radio resource control connection release message according to the radio resource control connection release message. For example, when the information carried on the redirection carrier information field of the rrc connection release message is fifth generation mobile communication technology carrier information (carrierlnfo nr), the terminal accesses the 5G mobile communication network according to the rrc connection release message; when the information carried on the redirection carrier information field of the radio resource control connection release message is Global Mobile communication radio access network carrier frequency information (carrier freqgeran), the terminal is accessed to a Global System for Mobile Communications (GSM) System according to the radio resource control connection release message; when the information carried on the redirection carrier information field of the Radio resource control connection release message is the absolute Radio channel number value information (ARFCN-value UTRA) of the Universal Terrestrial Radio Access network, the terminal accesses the Universal Terrestrial Radio Access (UTRA) network according to the Radio resource control connection release message; when the information carried on the redirection carrier information field of the radio resource control connection release message is Code Division Multiple Access (CDMA) carrier frequency information (Carrier FreqCDMA 2000), the terminal accesses to a CDMA network according to the radio resource control connection release message; and when the information carried on the redirection carrier information field of the radio resource control connection release message is absolute radio channel number value information (ARFCN-value EUTRA) of the Evolution universal terrestrial radio access network, the terminal accesses to a Long Term Evolution (LTE) system of the global system for mobile communication according to the radio resource control connection release message.

Fig. 2 is a schematic flowchart of an IMS voice communication method provided in an embodiment of the present application, and fig. 3 is a schematic flowchart of another IMS voice communication method provided in an embodiment of the present application. As shown in fig. 2 and 3, the terminal initiates a calling service. It should be understood that the IMS voice communication process mainly uses a Session Initiation Protocol (SIP) Protocol to establish, modify, and terminate the IMS voice communication Session.

As shown in fig. 2, the IMS voice communication method mainly includes:

201. the terminal sends a request (INVITE) message to the access network device requesting a session to be established with the called subscriber.

202. The terminal receives an attempt 100 (Trying) message sent by the access network device, wherein the attempt 100 (Trying) message is used for indicating that the request message is received.

203. The terminal receives a Ringing 180 message sent by the access network equipment, and the Ringing 180 message is used for indicating the terminal to ring.

204. The terminal receives a good 200 (OK) message sent by the access network equipment, and the good 200 (OK) message is used for indicating the called user to answer the session.

205. The terminal sends an Acknowledgement (ACK) message to the access network device that a final response to the request message has been received.

206. And the terminal receives a BYE message sent by the access network equipment, wherein the BYE message is used for indicating the session ending.

207. The terminal sends a good 200 (OK) message to the access network device, the good 200 (OK) message being used in response to the BYE message.

Alternatively, as shown in fig. 3, the IMS voice communication method mainly includes portions 301 to 307, where the portions 301 to 305 are the same as the portions 201 to 205, and are not repeated here.

306. The terminal sends a BYE message to the access network device, wherein the BYE message is used for indicating the session ending.

307. The terminal receives a good 200 (OK) message sent by the access network equipment, and the good 200 (OK) message is used for responding to the BYE message.

As can be seen from fig. 2 and 3, the terminal represents the end of the IMS voice communication when transmitting the BYE message and receiving the good 200 (OK) message, or when receiving the BYE message and transmitting the good 200 (OK) message. The difference between the flow diagrams of the IMS voice communication methods illustrated in fig. 2 and fig. 3 is mainly that the IMS voice communication is terminated by the originating party or the called party.

In order to better understand the embodiments of the present application, the following detailed description will be made with reference to the flowchart shown in fig. 4. Referring to fig. 4, fig. 4 is a flowchart illustrating another IMS voice communication method according to an embodiment of the present application. As shown in fig. 4, the IMS voice communication method includes portions 401 to 403, in which:

401. and the first access network equipment sends an EPS (evolved packet System) fallback indication message to the terminal.

In this embodiment of the application, a first access network device sends an EPS fallback indication message to a terminal, where the EPS fallback indication message is used to indicate that the terminal is switched from a first access network device of a 5G mobile communication network to a second access network device of a 4G mobile communication network. It should be noted that the EPS fallback indication message is used to indicate that the terminal is executing the fallback process, and before receiving the EPS fallback indication message, the terminal cannot accurately know whether the fallback occurs from the air interface.

In an implementation manner, the EPS fallback indication message may be a mobility message (mobility fromnrcommm) message from a new radio command specified in the 3gpp technical specification, or may be a radio resource control release (rrcreelease) message.

In an implementable manner, before the first access network device sends the EPS fallback indication message to the terminal, the first access network device initiates IMS voice communication to the terminal, or the terminal initiates IMS voice communication to the first access network device, which is not limited in this application. A process in which the terminal initiates the IMS voice communication to the first access network device is called a calling party (MO), and a process in which the first access network device initiates the IMS voice communication to the terminal is called a called party (MT).

402. After receiving an EPS fallback indication message sent by a first access network device, a terminal connects from the first access network device supporting a fifth-generation mobile communication network to a second access network device supporting a fourth-generation mobile communication network to perform IMS voice communication.

In the embodiment of the application, after receiving an EPS fallback indication message sent by a first access network device supporting a 5G mobile communication network, a terminal accesses a second access network device supporting a 4G mobile communication network according to the EPS fallback indication message to fallback to the 4G mobile communication network, and performs IMS voice communication through the 4G mobile communication network. The IMS voice communication through the 4G mobile communication network means that the second access network device allocates wireless resources for IMS voice communication, and establishes a Quality of Service (QoS Flow) for transmitting Service data of the IMS voice communication between the terminal and the access network device, so as to complete the IMS voice communication.

403. And after the terminal finishes the IMS voice communication, when receiving a radio resource control connection release message, accessing to a fifth generation mobile communication network, wherein the radio resource control connection release message does not carry redirection carrier information.

In the embodiment of the present application, the terminal fallback is caused by that the 5G mobile communication network does not support IMS voice communication, and the terminal needs to return to the 5G mobile communication network after completing IMS voice communication, so as to obtain a higher-quality communication service as much as possible. Specifically, after the terminal completes the IMS voice communication, the terminal autonomously accesses the 5G mobile communication network when receiving a radio resource control connection release message that is sent by the second access network device and does not carry the redirection carrier information. To return to the 5G mobile communication network, the terminal may access any access network device under the 5G mobile communication network, including but not limited to the first access network device. For example, the terminal may re-access to the first access network device supporting the fifth generation mobile communication network, or search for and access to the third access network device supporting the fifth generation mobile communication network. The process of the terminal autonomously accessing to the 5G mobile communication network may be a conventional terminal network access process, and for example, mainly includes three stages: the first stage, cell search and cell selection; the second stage, random access; the third stage, REGISTRATION (REGISTRATION).

In one possible implementation, the terminal marks the end of IMS voice communication after sending the BYE message and receiving the good 200 (OK) message, or after receiving the BYE message and sending the good 200 (OK) message. The BYE message and the good 200 (OK) message are messages in a session initiation protocol, the BYE message is used for indicating that the IMS voice communication is ended, and the good 200 (OK) message is used for responding to the BYE message.

It should be noted that, after the terminal completes the IMS voice communication, if a radio resource control connection release message that does not carry information of the redirection carrier is received, it is equivalent to identifying that the current scenario is a scenario that needs to be returned autonomously. Otherwise, it is recognized that the current scenario is not a scenario requiring autonomous return, and thus an invalid autonomous return attempt is not made.

It should also be noted that the terminal may determine whether IMS voice communication is currently in progress. When the terminal initiates an IMS voice communication to the access network device, or when the access network device initiates an IMS voice communication to the terminal, the terminal may send or receive an Invite (Invite) signaling for initiating an IMS voice communication. Therefore, if the terminal detects that the terminal sends or receives an Invite (Invite) signaling, it may determine that the terminal is performing IMS voice communication.

It should be noted that the reason why the terminal needs to return to 5G after completing the IMS voice communication is that the terminal receives a REGISTRATION receipt (REGISTRATION ACCEPT) message sent by the first access network device under 5G before falling back, where the REGISTRATION receipt message indicates that the 5G mobile communication network does not support IMS voice communication. Therefore, when the terminal performs IMS voice communication after the fallback, it can be determined that the fallback is caused because the 5G mobile communication network does not support IMS voice communication, and thus it is required to return to the 5G mobile communication network after the IMS voice communication is completed. Wherein, the internet protocol multimedia subsystem packet voice service (IMS-VoPS) field in the registration received message records the content of whether the 5G mobile communication network supports the currently accessed IMS voice communication, and if the value in the IMS-VoPS field is 00, it represents that the 5G mobile communication network does not support the currently accessed IMS voice communication.

There are many cases where the terminal accesses a fifth-generation mobile communication network after completing IMS voice communication, including mainly four cases. These four cases will be described in detail next.

In the first case: and after the terminal finishes IMS voice communication, when receiving a wireless resource control connection release message which does not carry the redirection carrier information, accessing to the fifth generation mobile communication network.

In the embodiment of the application, after the IMS voice communication is completed, if a radio resource control connection release message that does not carry the redirection carrier information is received, the terminal autonomously accesses to the 5G mobile communication network. Because the radio resource control connection release message sent by the second access network device does not carry the redirection carrier information, it indicates that the second access network device does not support redirecting the terminal to the 5G mobile communication network. Therefore, when the terminal completes IMS voice communication and determines that the second access network equipment under the 4G mobile communication network does not support the redirection of the terminal to the 5G mobile communication network, the terminal autonomously initiates a network access flow accessed to the 5G mobile communication network so as to access to the 5G mobile communication network.

In the second case: after the terminal finishes IMS voice communication, the terminal receives a radio resource control connection release message which does not carry redirection carrier information, and accesses to a fifth generation mobile communication network when the quality of service flow of the IMS voice does not exist before receiving the EPS fallback indication message of the evolution packet system.

The embodiment of the application can further determine whether the fallback is caused by that the 5G mobile communication network does not support IMS voice communication. Specifically, the method comprises the following steps. The terminal does not detect the QoS Flow of the IMS voice communication before receiving the EPS fallback indication message, which may indicate that the IMS voice Flow is initiated between the terminal and the first access network device under 5G, but the QoS Flow of the IMS voice communication is not established, so that the fallback of the terminal may be more accurately determined because the 5G mobile communication network does not support the IMS voice communication. Therefore, after the terminal finishes the IMS voice communication, the terminal accesses to a fifth generation mobile communication network when receiving the radio resource control connection release message which does not carry the redirection carrier information and when the quality of service flow of the IMS voice does not exist before receiving the EPS fallback indication message.

It should be noted that after the IMS voice communication is initiated, a QoS Flow is established between the terminal and the access network device to transmit data of the IMS voice communication. The QoS Flow includes not only traffic data (e.g., voice data and video data of a user) of IMS voice communication but also a QoS identifier (5 QI) of the QoS Flow. And the terminal determines whether the QoS Flow established between the terminal and the access network equipment is the QoS Flow of the IMS voice communication by reading the 5QI of the QoS Flow. Specifically, the terminal detects whether a 5QI of a QoS Flow established between the terminal and the access network device is 1 or 2, and if yes, determines that the QoS Flow of the IMS voice communication is detected. If the 5QI of the QoS Flow is 1, determining that the QoS Flow of the IMS Voice communication is the QoS Flow of a Voice service (switching Voice); if the 5QI of the QoS Flow is 2, it is determined that the QoS Flow of the IMS voice communication is the QoS Flow of the Video service (centralized Video).

In a third case: and after the terminal finishes IMS voice communication, receiving a radio resource control connection release message which does not carry redirection carrier information, and accessing to a fifth generation mobile communication network when a measurement report is not reported within a preset time before receiving the EPS fallback indication message of the evolved packet system. The measurement report is a measurement report including any event, and the preset time duration may be any time duration, which is not limited in this application.

The embodiment of the application can determine that the 5G mobile communication network is caused by not supporting IMS voice communication, and can further determine whether the fallback is caused by poor communication quality of the terminal in the 5G mobile communication network by determining whether the terminal does not report the measurement report within the preset time before receiving the EPS fallback indication message. If the terminal does not report the measurement report within the preset time before receiving the EPS fallback indication message, determining that the fallback is not caused by the poor communication quality of the terminal in the 5G mobile communication network; if the terminal reports the measurement report within the preset time before receiving the EPS fallback indication message, the fallback may be caused by poor communication quality of the terminal in the 5G mobile communication network. If it is because the 5G mobile communication network does not support IMS voice communication but is not caused by poor communication quality, the terminal needs to return to the 5G mobile communication network after completing IMS voice communication in order to acquire a higher-quality communication service as much as possible. Therefore, after the terminal finishes the IMS voice communication, the terminal receives the radio resource control connection release message which does not carry the redirection carrier information, and accesses to a fifth generation mobile communication network when the measurement report is not reported within the preset time before the EPS fallback indication message is received.

It should be noted that the measurement report includes an event for indicating communication quality, and the access network device performs, for example, an operation of instructing the terminal to switch connection to another access network device according to the event in the measurement report after receiving the measurement report sent by the terminal, so as to improve the communication quality of the terminal. Therefore, when the terminal does not report the measurement report, the communication quality of the mobile communication network in which the terminal is currently located can be considered to be better. Therefore, in the case that the terminal does not report the measurement report within the preset time period before receiving the EPS fallback indication message, it may be determined that the terminal fallback is not caused by poor communication quality in the 5G mobile communication network.

In a fourth case: and after the terminal finishes IMS voice communication, receiving a radio resource control connection release message which does not carry redirection carrier information, and accessing to a fifth generation mobile communication network when a measurement report is not reported within a preset time before receiving the EPS fallback indication message of the evolved packet system. The measurement report is a measurement report including a B1 event, or a B2 event, or a B1 event and a B2 event. The preset time period may be any time period, which is not limited in this application.

The embodiment of the application may determine that the 5G mobile communication network is caused by not supporting IMS voice communication, and may determine that the fallback is not caused by poor communication quality of the terminal in the 5G mobile communication network by determining that the measurement report including the specific handover event is not reported within a preset time period before the evolved packet system EPS fallback indication message is received. If it is because the 5G mobile communication network does not support IMS voice communication but is not because the communication quality is poor, it is necessary to return to the 5G mobile communication network after completion of IMS voice communication in order to provide a higher-quality communication service to the terminal as much as possible. Therefore, after the terminal finishes the IMS voice communication, the terminal receives the radio resource control connection release message which does not carry the redirection carrier information, and accesses to a fifth generation mobile communication network when the measurement report containing the specific switching event is not reported in the preset time before the evolved packet system EPS fallback indication message is received. Wherein the specific handover event includes at least one of a B1 event and a B2 event.

It should be noted that all events included in the measurement report do not necessarily cause a fallback, and the fallback may be caused only when a specific handover event, such as at least one of a B1 event and a B2 event, is included in the measurement report. Specifically, the measurement report includes events for indicating communication quality, for example, a type a event for indicating communication quality of cells in the same system, and a type B event for indicating communication quality of cells between different systems. Since the 5G mobile communication network falls back to the 4G mobile communication network and belongs to the handover event of the heterogeneous system, the application only focuses on the B-type event in the measurement report, the B-type event comprises a B1 event and a B2 event, the B1 event means that the quality of the heterogeneous system cell is better than the threshold, the B2 event means that the quality of the serving cell is lower than the threshold 1, and the quality of the heterogeneous system cell is better than the threshold 2. Therefore, in the case that the terminal does not report the measurement report containing at least one of the B1 event and the B2 event within the preset time period before receiving the EPS fallback indication message, it may be determined that the terminal fallback is not caused by the poor communication quality in the 5G mobile communication network.

It can be seen that, in addition to the first case and the second case that it is only necessary to determine that the fallback is caused because the 5G mobile communication network does not support IMS voice communication, the third case and the fourth case that it is not only necessary to determine that the fallback is caused because the 5G mobile communication network does not support IMS voice communication, but also necessary to determine that the fallback is not caused because the communication quality of the terminal is poor when the 5G mobile communication network is in use.

It should be noted that, in addition to the above cases, the above cases may be combined, for example: after the terminal finishes IMS voice communication, the terminal receives a radio resource control connection release message, does not have the quality of service flow of the IMS voice before receiving an EPS fallback indication message, and is accessed to a fifth generation mobile communication network when a measurement report is not reported within a preset time length before receiving an EPS fallback indication message of an evolved packet system; also for example: after the terminal finishes IMS voice communication, the terminal receives a radio resource control connection release message, does not have the service quality flow of the IMS voice before receiving an EPS fallback indication message, and accesses to a fifth generation mobile communication network when a measurement report containing a specific switching event is not reported in a preset time before receiving an EPS fallback indication message of an evolved packet system. However, it should be noted that, although it can be determined more accurately whether the current scene is a scene that needs to be returned autonomously by combining the above four cases, it is found through practical verification that the above four cases can already determine very accurately whether the current scene is a scene that needs to be returned autonomously, and therefore, in some communication scenarios that are particularly concerned with communication delay and communication quality, any one of the above four cases is adopted alone, which shortens the determination time and returns autonomously to the 5G mobile communication network more quickly than the above combined case, and therefore, a better communication effect can be obtained.

From fig. 4 and the above description, it can be seen that the terminal does not in any case need to autonomously return to the 5G mobile communication network after falling back from the 5G mobile communication network to the 4G mobile communication network. After the terminal falls back to the 4G mobile communication network from the 5G mobile communication network and finishes the IMS voice service, whether the current scene is the scene needing to return to the 5G mobile communication network autonomously is automatically identified, and the current scene is automatically returned to the 5G mobile communication network in the scene needing to be returned autonomously. Specifically, after the terminal finishes IMS voice communication, if a radio resource control connection release message that does not carry redirection carrier information is received, it is determined that the second access network device in the 4G mobile communication network does not support redirection of the terminal to the 5G mobile communication network, and therefore the terminal autonomously returns to the 5G mobile communication network without an instruction of the second access network device in the 4G mobile communication network. Therefore, by the method, the terminal can autonomously identify whether the current scene is the scene needing autonomous return after the fallback. And the autonomous return is initiated in time under the scene that the autonomous return is needed, so that high-quality communication service is obtained as far as possible. In the scenario that autonomous return is not needed, invalid autonomous return attempts are reduced, because invalid autonomous return attempts seriously affect normal communication of the terminal. Therefore, the method of the embodiment can realize the high-efficiency communication process and improve the communication efficiency without upgrading the access network equipment under the 4G mobile communication network.

It should be noted that what is shown in fig. 1 and fig. 4 is an example and does not constitute a limitation to the embodiment of the present application, because the present application does not limit specific expressions of the terminal, the first access network device, the second access network device, and the like.

Referring to fig. 5, the embodiment of the present invention may perform functional unit division on the device according to the above method example, for example, each functional unit may be divided corresponding to each function, or two or more functions may be integrated into one unit. The integrated unit may be implemented in the form of hardware, or may also be implemented in the form of a software functional unit. It should be noted that the division of the unit in the embodiment of the present invention is schematic, and is only a logic function division, and there may be another division manner in actual implementation.

The invention also provides a wireless communication device. The wireless communication device includes a receiving unit 510 and a processing unit 520, specifically:

a receiving unit 510, configured to receive an EPS fallback indication message;

a processing unit 520, configured to switch from a first access network device supporting a fifth generation mobile communication network to a second access network device supporting a fourth generation mobile communication network, and perform an internet protocol multimedia subsystem IMS voice communication;

the receiving unit 510 is further configured to receive a radio resource control connection release message, where the radio resource control connection release message does not carry redirection indication information;

the processing unit 520 is configured to access to the fifth generation mobile communication network when receiving a rrc connection release message after the IMS voice communication is completed.

In an implementation manner, the processing unit 520 is specifically configured to: after the BYE message is sent and the good 200 (OK) message is received, or after the BYE message is received and the good 200 (OK) message is sent, when the radio resource control connection release message is received, accessing to the fifth generation mobile communication network; the BYE message and the good 200 (OK) message are messages in a session initiation protocol, the BYE message is used for indicating the end of the IMS voice communication, and the good 200 (OK) message is used for responding to the BYE message.

In an implementation manner, the processing unit 520 is specifically configured to: and accessing to the fifth generation mobile communication network when the radio resource control connection release message is received and the quality of service flow of the IMS voice does not exist before the evolved packet system EPS fallback indication message is received.

In an implementation manner, the processing unit 520 is specifically configured to: and when a radio resource control connection release message is received and a measurement report is not reported within a preset time before the Evolved Packet System (EPS) fallback indication message is received, accessing to the fifth generation mobile communication network.

In an implementable manner, the measurement report refers to a measurement report including a B1 event, or a B2 event, or a B1 event and a B2 event.

In an implementation manner, the EPS fallback indication message is a mobility message from a new radio command.

In an implementation manner, the EPS fallback indication message is a radio resource control release message.

In an implementation manner, the processing unit 520 is specifically configured to: and re-accessing to the first access network equipment supporting the fifth generation mobile communication network.

In an implementation manner, the processing unit 520 is specifically configured to: searching and accessing to a third access network device supporting a fifth generation mobile communication network.

Specifically, the wireless communication apparatus may implement, through the aforementioned units, part or all of the steps in the IMS voice communication method in the embodiment shown in fig. 4. It should be understood that the embodiments of the present application are device embodiments corresponding to method embodiments, and the description of the method embodiments also applies to the embodiments of the present application.

Fig. 6 is a schematic block diagram of a wireless communication device according to another embodiment of the present application. The wireless communication apparatus in the present embodiment as shown in the figure may include: a processor 610, a transceiver 620, and a memory 630. The processor 61, transceiver 620, and memory 630 are coupled by a bus 640.

The processor 610 may be a Central Processing Unit (CPU), a general purpose processor, a coprocessor, a Digital Signal Processor (DSP), an application-specific integrated circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic device, transistor logic device, hardware component, or any combination thereof. The processor 610 may also be a combination of computing functions, e.g., comprising one or more microprocessors, DSPs, and microprocessors, among others.

The processor 610 invokes the program code stored in the memory 630 to perform the steps performed by the wireless communication device in the above method embodiments. Specifically, the method comprises the following steps:

the transceiver 620 is configured to execute the function of the receiving unit 510, and is configured to receive an EPS fallback indication message; the processor 610 is configured to execute the function of the processing unit 520, and is configured to switch from a first access network device supporting a fifth generation mobile communication network to a second access network device supporting a fourth generation mobile communication network, so as to perform an internet protocol multimedia subsystem IMS voice communication; the transceiver 620 is further configured to receive a radio resource control connection release message, where the radio resource control connection release message does not carry redirection indication information; the processor 610 is further configured to access the fifth generation mobile communication network when receiving a rrc connection release message after the IMS voice communication is completed.

In an implementation manner, the processor 610 is specifically configured to: after the BYE message is sent and the good 200 (OK) message is received, or after the BYE message is received and the good 200 (OK) message is sent, when the radio resource control connection release message is received, accessing to the fifth generation mobile communication network; the BYE message and the good 200 (OK) message are messages in a session initiation protocol, the BYE message is used for indicating the end of the IMS voice communication, and the good 200 (OK) message is used for responding to the BYE message.

In an implementation manner, the processor 610 is specifically configured to: and accessing to the fifth generation mobile communication network when the radio resource control connection release message is received and the quality of service flow of the IMS voice does not exist before the evolved packet system EPS fallback indication message is received.

In an implementation manner, the processor 610 is specifically configured to: and when a radio resource control connection release message is received and a measurement report is not reported within a preset time before the Evolved Packet System (EPS) fallback indication message is received, accessing to the fifth generation mobile communication network.

In an implementable manner, the EPS fallback indication message is a mobility message from a new radio command.

In an implementation manner, the EPS fallback indication message is a rrc release message.

In an implementation manner, the processor 610 is specifically configured to: and re-accessing to the first access network equipment supporting the fifth generation mobile communication network.

In an implementation manner, the processor 610 is specifically configured to: searching and accessing to a third access network device supporting a fifth generation mobile communication network.

Based on the same inventive concept, the principle of the wireless communication apparatus provided in the embodiments of the present application to solve the problem is similar to that of the wireless communication apparatus provided in the embodiments of the method of the present application to solve the problem, so that the implementation of each device may refer to the implementation of the method, and is not described herein again for brevity.

Those skilled in the art will recognize that, in one or more of the examples described above, the functions described in this invention may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the scope of the present invention, and any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the present invention should be included in the scope of the present invention.

Claims

1. An internet protocol multimedia subsystem (IMS) voice communication method, comprising:

receiving an EPS (evolved packet System) fallback indication message;

switching from first access network equipment supporting a fifth generation mobile communication network to second access network equipment supporting a fourth generation mobile communication network to perform IMS voice communication;

and after the IMS voice communication is finished, accessing to the fifth generation mobile communication network when a radio resource control connection release message is received, wherein the radio resource control connection release message does not carry redirection carrier information.

2. The method according to claim 1, wherein the ending of the IMS voice communication specifically means after sending a BYE message and receiving a good 200 (OK) message, or after receiving a BYE message and sending a good 200 (OK) message, where the BYE message and the good 200 (OK) message are messages in a session initiation protocol, the BYE message is used to indicate the end of the IMS voice communication, and the good 200 (OK) message is used to respond to the BYE message.

3. The method according to claim 1, wherein the accessing to the fifth generation mobile communication network upon receiving the rrc connection release message comprises:

and accessing to the fifth generation mobile communication network when the radio resource control connection release message is received and the quality of service flow of the IMS voice does not exist before the EPS fallback indication message is received.

4. The method according to claim 1, wherein the accessing to the fifth generation mobile communication network upon receiving the rrc connection release message comprises:

and when a radio resource control connection release message is received and a measurement report is not reported within a preset time before the Evolved Packet System (EPS) fallback indication message is received, accessing to the fifth generation mobile communication network.

5. The method of claim 4, wherein the measurement report refers to a measurement report comprising a B1 event, or a B2 event, or a B1 event and a B2 event.

6. The method according to any of claims 1 to 5, wherein the EPS fallback indication message is a mobility message from a new radio command.

7. The method according to any of claims 1 to 5, wherein the EPS fallback indication message is a radio resource control release message.

8. The method according to any of claims 1 to 5, wherein said accessing the fifth generation mobile communication network specifically comprises:

re-accessing to the first access network device supporting the fifth generation mobile communication network.

9. The method according to any of claims 1 to 5, wherein said accessing the fifth generation mobile communication network specifically comprises:

searching for and accessing to a third access network device supporting the fifth generation mobile communication network.

10. A wireless communications apparatus, comprising:

a receiving unit, configured to receive an EPS fallback indication message;

the processing unit is used for switching from first access network equipment supporting a fifth generation mobile communication network to second access network equipment supporting a fourth generation mobile communication network to carry out Internet protocol multimedia subsystem (IMS) voice communication;

the receiving unit is further configured to receive a radio resource control connection release message, where the radio resource control connection release message does not carry redirection indication information;

and the processing unit is used for accessing to the fifth generation mobile communication network after the IMS voice communication is completed and when a radio resource control connection release message is received.

11. The wireless communication apparatus of claim 10, wherein the processing unit is specifically configured to:

accessing to the fifth generation mobile communication network when receiving a radio resource control connection release message after transmitting a BYE message and receiving a good 200 (OK) message, or after receiving a BYE message and transmitting a good 200 (OK) message; the BYE message and the good 200 (OK) message are messages in a session initiation protocol, the BYE message is used for indicating the end of the IMS voice communication, and the good 200 (OK) message is used for responding to the BYE message.

12. The wireless communication apparatus of claim 10, wherein the processing unit is specifically configured to:

and accessing to the fifth generation mobile communication network when the radio resource control connection release message is received and the quality of service flow of the IMS voice does not exist before the evolved packet system EPS fallback indication message is received.

13. The wireless communication apparatus of claim 10, wherein the processing unit is specifically configured to:

14. The wireless communications apparatus of claim 13, wherein the measurement report refers to a measurement report including a B1 event, or a B2 event, or a B1 event and a B2 event.

15. A wireless communication apparatus according to any of claims 10 to 14, wherein the EPS fallback indication message is a mobility message from a new radio command.

16. The wireless communications apparatus of any of claims 10-14, wherein the EPS fallback indication message is a radio resource control release message.

17. The wireless communication device according to any of claims 10 to 14, wherein the processing unit is specifically configured to:

and re-accessing to the first access network equipment supporting the fifth generation mobile communication network.

18. The wireless communication device according to any of claims 10 to 14, wherein the processing unit is specifically configured to:

searching and accessing to a third access network device supporting a fifth generation mobile communication network.

19. A wireless communication apparatus, which may be a terminal device or an apparatus for a terminal device, includes a processor and a transceiver, wherein the processor is connected to the transceiver;

the transceiver is used for receiving an EPS fallback indication message;

the processor is used for switching from a first access network device supporting a fifth generation mobile communication network to a second access network device supporting a fourth generation mobile communication network to perform IMS voice communication;

the transceiver is further configured to receive a radio resource control connection release message, where the radio resource control connection release message does not carry redirection indication information;

the processor is further configured to access the fifth-generation mobile communication network after the IMS voice communication is ended and when a radio resource control connection release message is received.

20. A communication system, comprising a wireless communication device and a first access network apparatus, wherein:

the first access network equipment is used for sending an EPS fallback indication message to the wireless communication device;

the wireless communication device is configured to receive an EPS fallback indication message sent by the first access network device, and switch from a first access network device supporting a fifth-generation mobile communication network to a second access network device supporting a fourth-generation mobile communication network according to the EPS fallback indication message, so as to perform IMS voice communication;

the wireless communication device is further configured to access the fifth-generation mobile communication network after the IMS voice communication is ended and when a radio resource control connection release message is received, where the radio resource control connection release message does not carry redirection carrier information.