Communication method and device

Abstract

The invention provides a communication method and device, relates to the technical field of communication, and is used for solving the problem that a terminal cannot use a voice service under the condition of an IMS network fault. The method comprises: a terminal receiving a first message, the first message being used for indicating that a proxy session control function is unreachable, and the first message indicating a first duration; and when the first duration expires or is overtime, the terminal sends a second message, and the second message is used for requesting to access the proxy session control function.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0002] With the development of mobile communication technology, Internet Protocol Multimedia Subsystem (IMS) technology has emerged, gradually replacing traditional circuit-switched (CS) voice communication technology in second-generation (2G) or third-generation (3G) networks. IMS can be carried over fourth-generation (4G) or fifth-generation (5G) networks to implement voice control, referred to as Voice over Long Term Evolution (VoLTE) and Voice over New Radio (VoNR) respectively. VoLTE or VoNR can provide shorter connection times for high-definition voice to user equipment (UE).

[0003] Currently, CS network and IMS network are deployed together. When a UE initiates a voice call in a 4G or 5G network, in scenarios such as IMS network failure or voice call failure, circuit-switched fallback (CS Fallback, CSFB) can be used to enable the UE to access the 2G or 3G network and make a voice call through the CS network. After the voice call ends, the UE can then access the 4G or 5G network.

[0004] However, the CS network faces numerous problems, including outdated equipment, obsolete underlying architecture, and high maintenance costs. The CS network will be gradually phased out or shut down. Therefore, without the CS network, terminals may be unable to use voice services properly in the event of an IMS network failure, resulting in a poor user experience. Summary of the Invention

[0005] This application provides a communication method and apparatus to solve the problem that terminals cannot use voice services in the event of an IMS network failure.

[0006] In a first aspect, a communication method is provided, which can be executed by a communication device, which may be a terminal, a module (such as a chip, chip system, or circuit) in the terminal, or a module or software capable of implementing all or part of the terminal's functions. The method includes: receiving a first message indicating that a proxy session control function is unreachable, the first message indicating a first duration; and when the first duration expires or times out, sending a second message requesting access to the proxy session control function.

[0007] In the above embodiments, the network device sends a first message to the terminal, enabling the terminal to determine that the proxy session control function of the current IMS network is unreachable. Based on this notification message, the terminal can then retry accessing the proxy session control function after a certain period of time, i.e., re-request access to the IMS network. Optionally, the terminal can periodically request access to the IMS network for a specified period of time until successful access is achieved, enabling communication services through the IMS network. This effectively solves the problem of temporary unavailability of the proxy session control function in the IMS network, improving communication efficiency and enhancing user experience by instructing the terminal to re-request access to the IMS network.

[0008] In one implementation, the first message includes a first error code, which indicates that the proxy session control function is unavailable.

[0009] In the above embodiments, the terminal can determine that the proxy session control function in the current IMS network is unreachable by the first error code carried in the first message it receives, and thus can trigger a re-request to access the proxy session control function after a first period of time.

[0010] In one implementation, sending a second message to a network device includes: detecting that no accessible circuit-switched (CS) network exists, and sending the second message to the network device after the first duration has expired or timed out.

[0011] In the above implementation, when the proxy session control function in the IMS network is unreachable, the terminal can detect whether there is an accessible CS network. If there is an accessible CS network, voice call service can be implemented through CS technology. If there is no accessible CS network, the terminal can re-request access to the IMS network after a specified period of time to implement voice call service.

[0012] In one implementation, the first message is a packet data network connection rejection message, and the second message is a packet data network connection request message.

[0013] The above-described embodiments of this application can be applied to 4G networks. The network can indicate to the terminal that the proxy session control function in the IMS network is unreachable through a packet data network connection rejection message. Thus, the terminal can resend a packet data network connection request message to the network after the first duration expires or times out, in order to request access to the proxy session control function.

[0014] In one implementation, the first message is a session establishment rejection message, and the second message is a session establishment request message.

[0015] The above-described embodiments of this application can be applied to 5G networks. The network can indicate to the terminal through a session establishment rejection message that the proxy session control function in the IMS network is unreachable. Thus, the terminal can resend a session establishment request message to the network after the first duration expires or times out, in order to request access to the proxy session control function.

[0016] In one implementation, the second message includes first information indicating the address for obtaining the proxy session control function.

[0017] Secondly, a communication method is provided, which can be executed by a communication device. The communication device can be a network device, a module (such as a chip, chip system, or circuit) within the network device, or a module or software capable of implementing all or part of the functions of the network device. For example, the communication device can be a mobility management device, and the method includes: determining that a proxy session control function is unreachable; sending a first message to a terminal, the first message indicating that the proxy session control function is unreachable, the first message indicating a first duration, the first duration indicating the waiting time for the terminal to request access to the proxy session control function.

[0018] In the above embodiments, when the network device determines that the proxy session control function of the IMS network is unreachable, it can send a first message to the terminal to indicate that the proxy session control function of the IMS network is currently unreachable. The terminal can then, based on this notification message, retry accessing the proxy session control function after a specified duration, i.e., re-request access to the IMS network. Optionally, the terminal can periodically request access to the IMS network for a specified duration until successful access is achieved, enabling communication services through the IMS network. This effectively solves the problem of temporary unavailability of the proxy session control function in the IMS network, improving communication efficiency and enhancing user experience by instructing the terminal to re-request access to the IMS network.

[0019] In one implementation, the first message includes a first error code, which indicates that the proxy session control function is unavailable.

[0020] In one implementation, determining that a proxy session control function is unreachable includes: receiving a third message indicating that the proxy session control function is unreachable; and determining that the proxy session control function is unreachable based on the third message.

[0021] In the above embodiments, the mobility management device in the network can autonomously determine that the proxy session control function is unreachable, or it can determine that the current proxy session control function is unreachable by receiving a third message from other network elements and according to the indication of the third message. In other words, the mobility management device can flexibly determine that the proxy session control function in the IMS network is unreachable.

[0022] In one implementation, the third message includes the first duration.

[0023] In the above embodiments, the mobility management device can receive a third message and obtain a first duration from the third message, that is, the mobility management device can obtain the waiting time for the terminal to re-request the access proxy session control function from other network elements. Alternatively, if the third message does not include the first duration, the mobility management device can determine the waiting time for the terminal to re-request the access proxy session control function according to pre-configuration or protocol agreement.

[0024] In one implementation, the mobility management device is an access and mobility management function (AMF) or a mobility management entity (MME).

[0025] In the above embodiments, the above embodiments of this application can be applied to 4G networks or 5G networks. For 4G networks, the MME can indicate to the terminal that the proxy session control function in the IMS network is unreachable through a packet data network connection rejection message. For 5G networks, the AMF can indicate to the terminal that the proxy session control function in the IMS network is unreachable through a session establishment rejection message, so that the terminal can resend the session establishment request message to the network after the first duration expires or times out, in order to request access to the proxy session control function.

[0026] In one embodiment, the method further includes: receiving a second message from the terminal, the second message being used to request access to the proxy session control function.

[0027] In the above embodiments, after the mobility management device indicates the current access proxy session control function to the terminal, the mobility management device can also receive request messages from the terminal for the access proxy session control function, such as the second message, to improve the efficiency of the terminal successfully accessing the proxy session control function, so as to realize communication services through the IMS network, improve communication efficiency and user experience.

[0028] In one implementation, the first message is a session establishment rejection message, and the second message is a session establishment request message.

[0029] In one implementation, the first message is a packet data network connection rejection message, and the second message is a packet data network connection request message.

[0030] In one implementation, the second message includes first information indicating the address for obtaining the proxy session control function.

[0031] Thirdly, a communication method is provided, which can be executed by a communication device. The communication device can be a network device, a module (such as a chip, chip system, or circuit) within the network device, or a module or software capable of implementing all or part of the functions of the network device. For example, the communication device can be a session management device, and the method includes: the session management device determining that a proxy session control function is unreachable; and sending a third message to a mobility management device, the third message indicating that the proxy session control function is unreachable.

[0032] In one implementation, the third message includes a first error code indicating that the proxy session control function is unavailable.

[0033] In one implementation, the third message includes a first duration, which indicates the waiting time for the terminal to request access to the proxy session control function.

[0034] In one embodiment, the method further includes: a mobility management device receiving the third message and determining, based on the third message, that the proxy session control function is unreachable; the mobility management device sending a first message to the terminal, the first message indicating that the proxy session control function is unreachable, the first message indicating a first duration, the first duration indicating the waiting time for the terminal to request access to the proxy session control function.

[0035] In one implementation, the session management device is a packet data network (PDN) gateway, and the mobility management device is a mobility management entity (MME).

[0036] In one implementation, the session management device is a session management function (SMF), and the mobility management device is an access and mobility management function (AMF).

[0037] Fourthly, a communication device is provided for implementing the above-described method. This communication device may be an apparatus for performing the methods of the first, second, or third aspects described above, or a node or device containing the aforementioned apparatus, or a module within the aforementioned apparatus, such as a chip, chip system, or circuit, or a logic node, logic module, or software capable of implementing some or all of the functions.

[0038] The apparatus includes modules, units, or means that implement the methods described above. These modules, units, or means can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions described above.

[0039] In one possible implementation, the device may include a processing module and a transceiver module. The processing module can be used to implement the processing functions in any of the above aspects and any possible implementations thereof. The processing module may be, for example, a processor. The transceiver module, also referred to as a transceiver unit, is used to implement the sending and / or receiving functions in any of the above aspects and any possible implementations thereof. The transceiver module may include: transceiver circuitry, transceiver, transceiver unit, or communication interface.

[0040] In one possible implementation, the transceiver module includes a sending module and a receiving module, which are used to implement the sending and receiving functions in any of the above aspects and any possible implementations.

[0041] Fifthly, a communication device is provided, comprising: a processor; the processor being coupled to a memory and, after reading instructions from the memory, executing the method as described in any of the preceding aspects according to the instructions. The communication device may be a device as described in the first, second, or third aspects, or a node or device containing the aforementioned device, or a module of the aforementioned device, such as a chip, chip system, or circuit, or a logic node, logic module, or software capable of implementing some or all of the functions.

[0042] In one possible implementation, the communication device further includes a memory for storing program instructions and / or data. Optionally, the memory and processor are integrated together.

[0043] In one possible implementation, the communication device is a chip or a chip system. Optionally, when the communication device is a chip system, it can be composed of chips or may include chips and other discrete components.

[0044] A sixth aspect provides a communication device, comprising: a processor and an interface circuit; the interface circuit being configured to receive a computer program or instructions and transmit them to the processor; the processor being configured to execute the computer program or instructions to cause the communication device to perform the method described in any of the preceding aspects. The communication device may be a device as described in the first, second, or third aspects above, or a node or device containing the aforementioned device, or a module of the aforementioned device, such as a chip, chip system, or circuit, or a logic node, logic module, or software capable of implementing some or all of the functions.

[0045] In one possible implementation, the communication device is a chip or a chip system. Optionally, when the communication device is a chip system, it can be composed of chips or may include chips and other discrete components.

[0046] In a seventh aspect, a computer-readable storage medium is provided, which stores instructions that, when executed on a computer, cause the computer to perform the methods described in any of the preceding aspects.

[0047] Eighthly, a computer program product containing instructions is provided, which, when run on a computer, enables the computer to perform the methods described in any of the preceding aspects.

[0048] A ninth aspect provides a communication system comprising a terminal performing the method described in the first aspect above, and a network device performing the method described in the second aspect above. For example, the network device performing the method described in the second aspect above may be a mobility management device.

[0049] In one possible implementation, the communication system includes a communication device that performs the method described in the third aspect above. For example, the communication device that performs the method described in the third aspect above may be a session management device.

[0050] The technical effects of any of the possible implementations of aspects two through nine can be found in the technical effects of the different possible implementations of aspect one above, and will not be repeated here.

[0051] Understandably, provided that the solutions do not contradict each other, the solutions in the above aspects can be combined. Attached Figure Description

[0052] Figure 1 This application provides a schematic diagram of the architecture of a communication system.

[0053] Figure 2 This is a schematic diagram of the architecture of another communication system provided in an embodiment of this application;

[0054] Figure 3 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0055] Figure 4 A flowchart illustrating a communication method provided in an embodiment of this application;

[0056] Figure 5 A flowchart illustrating another communication method provided in an embodiment of this application;

[0057] Figure 6 A flowchart illustrating another communication method provided in an embodiment of this application;

[0058] Figure 7 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0059] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this embodiment, unless otherwise stated, "a plurality of" means two or more.

[0060] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0061] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0062] First, a brief introduction will be given to the implementation environment and application scenarios of the embodiments of this application.

[0063] The communication method provided in this application can be applied to fourth-generation (4G) communication systems, such as long-term evolution (LTE) communication systems or evolved packet system (EPS) networks, as well as fifth-generation (5G) communication systems, such as 5G new radio (NR) communication systems, or various communication systems evolving after 5G, and future communication systems. The 4G core network is called the evolved packet core (EPC), and the 5G core network is called the 5G core network (5G Core (5GC)).

[0064] For example, Figure 1 This application illustrates a network architecture to which this application applies, wherein, Figure 1Taking the network service architecture of a 5G system as an example, this paper illustrates the interaction relationship between network functions (NFs) and entities, as well as their corresponding interfaces. The 3rd generation partnership project (3GPP) service-based architecture (SBA) for 5G systems includes the following network functions and entities: user equipment (UE), at least one access network (AN) or radio access network (RAN) node, user plane function (UPF), data network (DN), access and mobility management function (AMF), session management function (SMF), policy control function (PCF), application function (AF), unified data management (UDM), network exposure function (NEF), unified data repository (UDR), authentication server function (AUSF), network repository function (NRF), network slice selection function (NSSF), and network slice specific authentication and authorization (BSA) elements. Functions such as NSSAAF (Network Data Analytics Function) and Network Data Analytics Function (NWDAF) are also available.

[0065] In this context, the UE, radio access network (RAN) node, UPF, and DN are generally referred to as user plane network functions and entities (or user plane network elements), while the others are generally referred to as control plane network functions and entities (or control plane network elements). Control plane network elements, defined by 3GPP, define the processing functions within a network. They possess 3GPP-defined functional behaviors and interfaces. An NF can function as a network element running on proprietary hardware, a software instance running on proprietary hardware, or a virtual function instantiated on a suitable platform, such as a cloud infrastructure.

[0066] The main functions of each network function are described in detail below.

[0067] The user plane network functions in the communication system include:

[0068] (R)AN Node: A (R)AN can be an AN, a RAN, or an access network device, RAN entity, or access node, etc., forming part of the communication system to help terminal devices access the communication network. For example, a (R)AN can be various types of base stations, such as macro base stations, micro base stations, radio controllers, relay stations, access points, or network equipment in vehicle-mounted devices, wearable devices, or future Public Land Mobile Networks (PLMNs). The (R)AN is primarily responsible for air interface-side radio resource management, quality of service management, data compression, and encryption.

[0069] In addition, (R)AN nodes can also be access nodes in open RAN (O-RAN or ORAN), cloud radio access network (CRAN), or wireless fidelity (WiFi) systems, or access nodes in communication systems that integrate two or more of the above systems.

[0070] In one possible scenario, a RAN node can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB) in a future mobile communication system, or an access node in a WiFi system. A RAN node can be a macro base station, a micro base station, an indoor station, a relay node, a donor node, or a radio controller in a CRAN scenario. Optionally, a RAN node can also be a server, a wearable device, a vehicle, or in-vehicle equipment. For example, the access network equipment in vehicle-to-everything (V2X) technology can be a roadside unit (RSU). All or part of the functions of the RAN node in this application can also be implemented through software functions running on hardware, or through virtualization functions instantiated on a platform (e.g., a cloud platform). The RAN node in this application can also be a logical node, logical module, or software capable of implementing all or part of the RAN node functions.

[0071] In another possible scenario, multiple RAN nodes collaborate to assist terminal devices in achieving wireless access, with different RAN nodes each implementing some of the base station's functions. For example, RAN nodes can be central units (CUs), distributed units (DUs), CU-control plane (CPs), CU-user plane (UPs), or radio units (RUs), etc. CUs and DUs can be set up separately or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio frequency equipment or radio frequency units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs).

[0072] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0073] UE: Also known as a terminal, terminal device, mobile station (MS), mobile terminal (MT), etc., it is a device used to provide voice or data connectivity to users, or an Internet of Things (IoT) device. For example, terminal devices include handheld devices with wireless connectivity, in-vehicle devices, etc. Currently, terminal devices can include: mobile phones, tablets, laptops, PDAs, mobile internet devices (MIDs), wearable devices (such as smartwatches, smart bracelets, pedometers, smart glasses, etc.), in-vehicle devices (such as cars, bicycles, electric vehicles, airplanes, ships, trains, high-speed trains, etc.), satellite terminals, virtual reality (VR) devices, augmented reality (AR) devices, point-of-sale (POS) machines, customer-premises equipment (CPE), light user equipment (UE), reduced capability user equipment (REDCAP UE), wireless terminals in industrial control, smart home devices (such as refrigerators, televisions, air conditioners, electricity meters, etc.), intelligent robots, robotic arms, workshop equipment, wireless terminals in autonomous driving, wireless terminals in telemedicine, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, or wireless terminals in smart homes, and flying equipment (such as intelligent robots, hot air balloons, drones, airplanes), etc. Terminal devices can also be vehicle devices, such as vehicle devices, vehicle modules, vehicle chips, onboard units (OBU), or telematics boxes (T-BOX). Terminal devices can also be other devices with terminal functions. For example, a terminal device can also be a device that plays a terminal function in D2D communication.

[0074] The embodiments of this application do not limit the form of the terminal device. The device used to implement the functions of the terminal device can be the terminal device itself, or it can be a device that supports the terminal device in implementing the functions, such as a chip system. The device can be installed in the terminal device or used in conjunction with the terminal device. In the embodiments of this application, the chip system can be composed of chips, or it can include chips and other discrete devices. All or part of the functions of the terminal device in this application can also be implemented by software functions running on hardware, or by virtualization functions instantiated on a platform (such as a cloud platform).

[0075] UPF: Primarily responsible for forwarding and receiving user plane data. The UPF can receive downlink data from the DN and then transmit that downlink data to the UE via (R)AN. The UPF can also receive uplink data from the UE via (R)AN and then forward that uplink data to the DN.

[0076] DN: For example, a DN can be an operator service network, an internet access network, or a third-party service network. A DN can exchange information with the UE through a PDU session. PDU sessions can be of various types, such as Internet Protocol version 4 (IPv4) and IPv6. For a 5GC network, the IMS network is a type of DN.

[0077] In addition, the control plane network functions in the communication system include:

[0078] AMF (Automatic Management Function): Primarily responsible for processing control plane messages and managing the mobility of terminal devices, including mobility state management, assigning temporary user identities, and authenticating and authorizing users. Examples include access control, mobility management, registration and deregistration, and network element selection.

[0079] SMF: Primarily used for session management, session establishment, allocation and management of UE's (private) IP address, responsible for session establishment, modification and release, and quality of service (QoS) control, etc.

[0080] UDM (User Authentication and Authorization Manager): Primarily used for authentication and credit processing, it manages subscription data, user identification, access authorization, registration / mobility management, subscription management, and SMS management. For example, when a user's subscription data is modified, the UDM is responsible for notifying the relevant network elements.

[0081] NEF: Primarily used to provide corresponding security guarantees to ensure the security of external applications to the communication network, providing functions such as opening up QoS customization capabilities for external applications, subscription to mobility state events, and distribution of AF requests.

[0082] NRF: Primarily used to provide internal / external addressing functions, etc.

[0083] AUSF: Primarily used for authentication processing functions, enabling two-way authentication between terminals and networks.

[0084] AF: Primarily used to send data routing information affecting applications to the network side, and to perform policy control through interaction between network open function elements and the policy framework.

[0085] PCF: Its main function is as a policy decision point, providing rules for detection, QoS, and flow-based charging control based on service data flows or applications. It can also provide policies to AMF and SMF, such as QoS policies and slice selection policies.

[0086] Furthermore, the IMS network can be carried on 4G or 5G networks to provide voice call services based on the Internet Protocol (IP).

[0087] The IMS network may include a Call Session Control Function (CSCF), which is mainly responsible for handling signaling control during multimedia call sessions. This includes managing user authentication in the IMS network, IMS bearer QoS, controlling Session Initiation Protocol (SIP) sessions in cooperation with other network entities, as well as service negotiation and resource allocation.

[0088] Based on their different functions, CSCFs can be divided into Proxy CSCFs (P-CSCF), Interrogating CSCFs (I-CSCF), and Serving CSCFs (S-CSCF). Essentially, they are all SIP servers used to process SIP signaling. The main functions of a P-CSCF include: forwarding SIP registration requests from terminals to the I-CSCF; and forwarding SIP messages from terminals to the S-CSCF. The P-CSCF determines the S-CSCF when the terminal initiates the registration process. The P-CSCF is the user access node in the IMS network.

[0089] Optional, such as Figure 1 As shown, an IMS network may include at least one Proxy-CallSession Control Function (P-CSCF).

[0090] in addition, Figure 2 This illustrates another network architecture to which this application applies. Figure 2Taking the network service architecture of a 4G system as an example, the network functions and entities included in a 4G system mainly include: UE, eNodeB, Mobility Management Entity (MME), Serving Gateway (S-GW), Packet Data Network Gateway (PDN-GW or P-GW), Home Subscription Server (HSS), Policy and Charging Rule Function (PCRF), and Service Capability Exposure Function (SCEF), etc.

[0091] MME: The key control node of the LTE access network, which is responsible for the location of UE (User Equipment) in idle mode, the paging process, including relaying.

[0092] S-GW: User plane access service gateway of EPC network, responsible for user data forwarding.

[0093] P-GW: Used to provide users with functions such as session management and bearer control, data forwarding, IP address allocation, and access for non-3GPP users. It is the anchor point for users to access the Packet Data Network (PDN).

[0094] HSS: The information processed includes: user identification, numbering and address information; user security information; user location information; user list information.

[0095] PCRF: It can control the QoS service quality of users and services, thereby providing users with differentiated services, as well as providing users with service flow carrying resources and traffic billing policies, such as Policy and Charging Control (PCC) rules.

[0096] SCEF exposes the services and capabilities of 3GPP network functions to third-party applications, and also allows third-party applications to provide information to 3GPP network functions.

[0097] It should be noted that, Figure 1 or Figure 2 The functions of other network elements included can be found in the relevant descriptions in conventional technologies, and will not be repeated here. Figure 1 or Figure 2The network architecture shown is for illustrative purposes only and is not intended to limit the technical solutions of this application. Those skilled in the art should understand that other network elements or devices may be included in the specific implementation, and the number of access network devices, terminal devices, and / or core network devices may be determined according to specific needs.

[0098] Optional, Figure 1 or Figure 2 Each network element shown can be a device, a functional module within a device, or a logical functional unit. It is understood that the aforementioned functions can be network components in hardware devices, such as communication chips in mobile phones, software functions running on dedicated hardware, or virtualization functions instantiated on a platform (e.g., a cloud platform).

[0099] Understandably, the above Figure 1 or Figure 2 In a communication system, devices or network elements can communicate directly or through forwarding from other devices. This application does not specifically limit this.

[0100] Understandably, the above Figure 1 or Figure 2 This is merely an illustrative diagram and does not constitute a limitation on the applicable scenarios of the technical solutions provided in this application. Those skilled in the art should understand that, in specific implementation processes, the communication system may include, for example, […]. Figure 1 or Figure 2 The number of devices or network elements shown may be fewer, or the communication system may include other devices or other network elements, and the number of devices or network elements in the communication system may be determined according to specific needs.

[0101] For example, Figure 1 or Figure 2 Each network element in the network can be accessed through Figure 3 This is achieved through the communication device 300. Figure 3 The diagram shows a hardware structure of a communication device applicable to embodiments of this application. The communication device 300 includes at least one processor 301, a communication line 302, and at least one communication interface 304. Optionally, the communication device 300 may further include a memory 303.

[0102] Processor 301 can be one or more Central Processing Units (CPUs). If the processor is a CPU, it can be a single-core CPU or a multi-core CPU. The processor can be a general-purpose processor, digital signal processor, application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly manifested as being executed by a hardware processor, or executed by a combination of hardware and software modules within the processor.

[0103] Optionally, the processor may include one or more of the following: a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a microprocessor unit (MPU), a microcontroller unit (MCU), a graphics processing unit (GPU), a field-programmable gate array (FPGA), an artificial intelligence processor (AI processor), or a neural processing unit (NPU).

[0104] Communication line 302 may include a path for transmitting information between the aforementioned components, such as a bus.

[0105] Communication interface 304 uses any transceiver-like device for communicating with other devices or communication networks, such as Ethernet interface, RAN interface, wireless local area network (WLAN) interface, etc.

[0106] The memory 303 may include, but is not limited to, cache, read-only memory (ROM), random access memory (RAM), synchronous dynamic random access memory (SDRAM), hard disk drive (HDD) or solid-state drive (SSD), erasable programmable read-only memory (EPROM), or compact disc read-only memory (CD-ROM), etc. Memory is any other medium capable of carrying or storing desired program code in the form of instructions or data structures that can be accessed by a computer, but is not limited to this. The memory in the embodiments of this application may also be a circuit or any other device capable of implementing storage functions for storing computer programs or instructions, and / or data. Optionally, the memory may exist independently and be connected to the processor via communication line 302. Optionally, the memory may also be integrated with the processor. The memory provided in the embodiments of this application can generally be non-volatile. The memory 303 stores computer execution instructions involved in the present application, and the processor 301 controls the execution of these instructions. The processor 301 executes the computer execution instructions stored in the memory 303 to implement the method provided in the embodiments of the present application.

[0107] Optionally, the computer execution instructions in the embodiments of this application may also be referred to as application code, and the embodiments of this application do not specifically limit this.

[0108] In a specific implementation, as one example, processor 301 may include one or more CPUs, for example... Figure 3 CPU0 and CPU1 in the CPU.

[0109] In a specific implementation, as one example, the communication device 300 may include multiple processors, such as... Figure 3 Processors 301 and 307 are described herein. Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor here may refer to one or more devices, circuits, and / or processing cores used to process data (e.g., computer program instructions).

[0110] In a specific implementation, as one embodiment, the communication device 300 may further include an output device 305 and an input device 306. The output device 305 communicates with the processor 301 and can display information in various ways. For example, the output device 305 may be a liquid crystal display (LCD), a light-emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector, etc. The input device 306 communicates with the processor 301 and can receive user input in various ways. For example, the input device 306 may be a mouse, keyboard, touchscreen device, or sensing device, etc.

[0111] The aforementioned communication device 300 can be a general-purpose device or a dedicated device. In specific implementations, the communication device 300 can be a portable computer, a network server, a handheld digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, an embedded device, or something similar. Figure 3 Devices with similar structures. This application does not limit the type of communication device 300 to any particular embodiment.

[0112] The communication method provided in the embodiments of this application will be described in detail below.

[0113] It should be noted that the message names between network elements or the names of parameters in the messages in the following embodiments of this application are just examples. Other names may be used in the specific implementation. This application does not limit them in this respect.

[0114] It is understood that some or all of the steps in the embodiments of this application are merely examples, and other steps or variations thereof may also be performed in the embodiments of this application. Furthermore, the steps may be performed in different orders as presented in the embodiments of this application, and it is not necessary to perform all the steps in the embodiments of this application.

[0115] This application proposes a communication method that can be applied to 4G networks, 5G networks, and future communication networks. In the event of an IMS network failure, the network can indicate to the terminal that the current proxy session control function is unreachable, thereby instructing the terminal to re-request access to the proxy session control function after a certain period of time. This solves the problem of unavailable voice call services when the IMS network fails, improves communication efficiency, and enhances user experience.

[0116] like Figure 4 As shown, the method may include the following steps.

[0117] 401: The network device has determined that the proxy session control function is unreachable.

[0118] In one implementation, the network device can be a core network element, such as a mobility management device. That is, the core network mobility management device can determine that the proxy session control function is unreachable before executing subsequent step 402. For example, for a 5G network, the mobility management device can specifically be an AMF; for a 4G network, the mobility management device can be an MME.

[0119] The unreachability of the proxy session control function can specifically include a failure of the proxy session control function in the IMS network, and / or a link failure (such as link disconnection or congestion) between the core network and the proxy session control function. In other words, the core network cannot currently establish a connection with the proxy session control function in IMS; therefore, network devices cannot provide communication services, such as voice call services, to terminals through the IMS network.

[0120] In one implementation, before step 401, the terminal triggers a proxy session control function discovery process, so that the network device can determine that the proxy session control function is unreachable based on the proxy session control function discovery process triggered by the terminal. The terminal's proxy session control function discovery process will be described in subsequent embodiments and will not be repeated here.

[0121] For example, the proxy session control function can refer to the P-CSCF in an IMS network.

[0122] In one implementation, the IMS network may include one or more proxy session control functions. If the IMS network includes multiple P-CSCFs, then the proxy session control functions are unreachable. Specifically, this may mean that all multiple proxy session control functions are unreachable, or that all P-CSCFs in the IMS network are unreachable.

[0123] 402: The network device sends a first message to the terminal, which indicates that the proxy session control function is unreachable.

[0124] After determining that the proxy session control function is unreachable, the network device can generate a first message, which indicates that the proxy session control function is unreachable.

[0125] In one implementation, the first message may carry a specific error code, such as a first error code, which may be used to indicate that the agent session control function is unavailable.

[0126] Correspondingly, the terminal receives the first message and, based on the first message, can determine that the proxy session control function in the current IMS network is unreachable. For example, the terminal receives the first message, obtains the first error code carried in the first message, and, based on the first error code, can determine that the proxy session control function is unreachable.

[0127] In addition, the first message can also indicate a first duration. The first duration is used to indicate the waiting time for the terminal to request access to the proxy session control function. That is, the first duration can be the waiting time for the terminal to re-request access to the IMS network. In other words, the network device can use the first message to indicate to the terminal that the proxy session control function is unreachable and to indicate that the retry waiting time is the first duration. After the first duration, the terminal can try to request access to the proxy session control function of the IMS network.

[0128] This application does not limit the specific method of indicating the first duration. For example, the first message may include a first duration, such as 1 millisecond (ms), in which case the first message may carry this duration value of 1ms. Alternatively, the network device and terminal may pre-configure several parameters for the first duration and their corresponding indices, such as pre-configuring the first duration values ​​as 1ms, 2ms, and 5ms, with corresponding indices of 00, 01, and 11. Thus, indicating one of the indices in the first message can indicate the value of the first duration corresponding to that index.

[0129] In one possible implementation, the network device and the terminal can be pre-configured to periodically re-request the access proxy session control function, or the first message sent by the network device to the terminal can indicate that the terminal can periodically re-request the access proxy session control function, wherein the first duration can be the period for re-accessing the IMS network, that is, the terminal can request the access proxy session control function every first duration.

[0130] For example, after receiving the first message, the terminal can periodically request access to the proxy session control function. That is, the terminal triggers a request to access the proxy session control function once every first time interval until the terminal successfully accesses the proxy session control function. For example, if the terminal receives a response message indicating successful access to the proxy session control function, the terminal will stop making periodic requests.

[0131] In another possible implementation, the maximum number of times the access proxy session control function can be repeatedly requested can be set. For example, the network device and the terminal can be pre-configured to periodically request the access proxy session control function a maximum number of times, such as three or five times; or, the first message sent by the network device to the terminal can also be used to indicate the number of repetitions.

[0132] For example, after receiving the first message, the terminal periodically requests access to the proxy session control function. That is, the terminal triggers a request to access the proxy session control function once every first time interval until the terminal successfully accesses the proxy session control function, or until the number of repeated requests reaches the indicated maximum number. For example, if the configured maximum number is three, the terminal receives a response message indicating successful access to the proxy session control function, or after receiving the first message, the terminal repeats the request to access the proxy session control function three times, and then the terminal stops periodically requesting access to the proxy session control function.

[0133] 403: When the first duration expires or times out, the terminal sends a second message to the network device to request access proxy session control function.

[0134] In other words, after receiving the first message, the terminal can send a second message to the network device after a first time interval.

[0135] In one implementation, after receiving the first message, the terminal can start a first timer. The duration of the first timer can be set to a first duration. When the first timer expires or times out, the terminal triggers the sending of a second message to the network device. The second message can be used to request access proxy session control function.

[0136] In one implementation, the terminal sends a second message to the network device, that is, the terminal re-triggers the P-CSCF discovery process. Correspondingly, the network device can receive the second message from the terminal.

[0137] In one implementation, the second message may include first information, which can be used to indicate the address for obtaining the proxy session control function. That is, the network device can include the first information in the second message to indicate that the terminal requests the address for obtaining the proxy session control function.

[0138] In one implementation, if the terminal is currently connected to a 4G network, the first message may be a packet data network connection rejection message (such as a PDN connectivity reject message), and the second message may be a packet data network connection request message (such as a PDN connectivity request message), referred to as a PDN connection request message.

[0139] For example, the PDN connection request message may include an indication of the network access technology (APN) and protocol configuration options (PCO). The APN can be used to indicate which access method the terminal uses to connect to the network. The PCO is used to provide additional information about the terminal's network connection.

[0140] For example, the APN carried in the PDN connection request message is the IMS APN, indicating that the terminal needs to access the IMS network; the PCO information element carried contains the P-CSCF address request (such as P-CSCF Address Request) parameter, that is, requesting the address of the P-CSCF.

[0141] In another implementation, if the terminal is currently connected to a 5G network, the first message can specifically be a session establishment rejection message, and the second message can specifically be a session establishment request message. For example, the first message can be a PDU session establishment reject message, used to instruct the network to refuse to establish a PDU session for the terminal; the second message can be a PDU session establishment request message, used to request the establishment of a PDU session.

[0142] For example, the PDU session establishment request message may include Extended Protocol Configuration Options (ePCO), which provides additional information for the terminal to connect to the network.

[0143] For example, the ePCO information element carried in the PDU session establishment request message may include a P-CSCF address request parameter (such as P-CSCF Address Request), which requests the address of the P-CSCF.

[0144] It should be noted that the terminal sends a request to the network device for access proxy session control function, such as the second message. Optionally, the terminal can send the request periodically until one or more unreachable P-CSCFs in the IMS network are cleared, allowing the terminal to successfully access the reachable P-CSCF. The specific interaction process can be found in the relevant technical procedures. Furthermore, the process of successful P-CSCF access may differ depending on the network architecture (e.g., 4G or 5G), and this application will not elaborate on this.

[0145] In one implementation, after determining that the P-CSCF is unreachable, the terminal can directly trigger a re-access to the P-CSCF; or, it can try to fall back to the CS network. If there is no CS network that can be accessed, the terminal will then request access to the P-CSCF again.

[0146] In other words, in one implementation, the terminal sends a second message to the network device, which may specifically include: the terminal detects that there is no accessible CS network, and sends a second message to the network device after the first time period expires or times out.

[0147] For example, a terminal can detect the existence of an accessible CS network by initiating an access request to the CS network. For instance, the terminal can send a CS service request (such as a CM Service Request) message to the Mobile Access Gateway Control Function (mAGCF), or a connect management service request message to the mAGCF. If the terminal does not receive a corresponding response message, it determines that no accessible CS network exists. Conversely, if the terminal receives a corresponding response message, it has detected an accessible CS network and can then use that network to make voice calls.

[0148] In one implementation, the specific implementation of the network device determining that the proxy session control function is unreachable in step 401 can include various methods. For example, the network device can request other network elements to obtain available proxy session control functions, thereby determining that the proxy session control function is unreachable. Alternatively, the network device can receive notification messages from other network elements to indicate that the proxy session control function is unreachable.

[0149] For example, if the network device is a mobility management device, before step 401, the session management device can send a third message to the mobility management device. This third message indicates that the proxy session control function is unreachable, thus allowing the mobility management device to determine that the proxy session control function is unreachable based on the third message. For instance, in a 5G network, the session management device can be an SMF (Service Management Function), and in a 4G network, it can be a PDN (Personal Domain Name) gateway. The PDN gateway can send a third message to the MME (Mechanical Management Equipment) through the serving gateway (S-GW).

[0150] Alternatively, in one possible implementation, the user plane function may send a third message to the mobility management device indicating that the proxy session control function is unreachable.

[0151] For example, if the network device is an SMF, the SMF can determine that the P-CSCF is unreachable in the following ways, as shown in the examples below:

[0152] (1) The P-CSCF will periodically register with the NRF. The NRF can determine whether there is an available P-CSCF, so the SMF can request the NRF to determine that the P-CSCF is unreachable.

[0153] (2) After the SMF obtains the list of accessible P-CSCF addresses through the NRF, it can save it locally and perform IP reachability detection on the P-CSCF, thereby determining that the P-CSCF is unreachable.

[0154] (3) The SMF may also receive notification messages from other network elements, such as the UPF. When the UPF detects that the P-CSCF is unreachable, the UPF can notify the SMF of the P-CSCF unreachability via the N4 interface message. Alternatively, the AMF can detect that the P-CSCF is unreachable and notify the SMF of the P-CSCF unreachability.

[0155] Subsequently, this application will describe the communication method provided by this application in conjunction with specific embodiments, including the specific implementation of how a network device determines that the proxy session control function is unreachable, which will not be elaborated here.

[0156] In one implementation, the network device is a mobility management device. The third message sent by the session management device to the mobility management device may include a first error code indicating that the proxy session control function is unreachable. Thus, the mobility management device can determine that the proxy session control function is unreachable based on the third message, then generate a first message and send it to the terminal to indicate that the proxy session control function is unreachable.

[0157] Optionally, the third message may include the waiting time for the terminal to re-request the access agent session control function, i.e., the first duration, or the third message may not include the first duration.

[0158] For example, the third message received by the mobility management device may include a first error code and a first duration. Thus, the mobility management device can determine that the proxy session control function is unreachable based on the third message, and then generate a first message and send it to the terminal. The first message may include the first error code and the first duration, indicating that the proxy session control function is unreachable, and the waiting time for the terminal to request re-access to the proxy session control function is the first duration.

[0159] Alternatively, in another implementation, the third message received by the mobility management device may include a first error code indicating that the proxy session control function is unreachable. Thus, the mobility management device can determine that the proxy session control function is unreachable based on the third message, and then generate a first message and send it to the terminal. The first message may include the first error code and a first duration, indicating that the proxy session control function is unreachable, and the first duration is the waiting time indicated by the mobility management device for the terminal to request re-access to the proxy session control function.

[0160] In the above embodiments, when the mobility management device in the network determines that the proxy session control function is unreachable, it can indicate to the terminal that the current proxy session control function is unreachable. The terminal can then, based on this indication, retry accessing the proxy session control function after a certain period of time, i.e., re-request access to the IMS network. Optionally, the terminal can periodically request access to the IMS network until successful access is achieved, thereby enabling communication services through the IMS network. The above embodiments of this application effectively solve the problem of temporary unavailability of the proxy session control function in the IMS network, improving communication efficiency and enhancing user experience by instructing the terminal to re-request access to the IMS network.

[0161] The following section, in conjunction with the accompanying drawings, will describe several possible specific implementation methods.

[0162] Example 1: Applied to 4G networks, combined with Figure 2 As shown, the network device is an MME as an example.

[0163] like Figure 5 As shown, the communication method includes the following steps.

[0164] 501: The UE attaches to the network upon power-on, establishing a default bearer between the UE and the APN.

[0165] The above process refers to the attachment process from the UE to the MME after the UE is powered on.

[0166] This includes the default bearer for establishing the UE to the APN, or the default bearer for the Quality of Service Class Identifier (QCI), i.e., QCI=9.

[0167] 502: The UE sends a PDN connection request message to the MME, requesting access to the IMS network.

[0168] The PDN connection request message carries an IMS APN, indicating that the UE needs to access the IMS domain. Furthermore, the PCO element in the PDN connection request message contains a P-CSCF Address Request parameter, which indicates a request to obtain a P-CSCF address.

[0169] 503: The MME sends a session establishment request message to the S-GW.

[0170] The session establishment request (e.g., create session request) message sent by the MME to the S-GW may include a default bearer ID, carry an IMS APN, include P-CSCF address request parameters in the PCO cell, and include the subscribed QoS profile (e.g., QCI=5).

[0171] 504: The S-GW sends a session establishment request message to the P-GW.

[0172] The session establishment request message may carry a PCO cell (P-CSCF address request parameter), the UE IP assigned by the P-GW, and the address of the selected P-CSCF.

[0173] 505: P-GW obtains the PCC rules of the UE from the PCRF.

[0174] Specifically, the PCRF can determine the strategy for EPS sessions based on the signed configuration file, select the rule corresponding to the SIP signaling as the PCC rule, and forward it to the P-GW.

[0175] 506: P-GW detected that P-CSCF is unreachable.

[0176] Specifically, the P-GW can detect that all P-CSCFs are unreachable through Internet Control Message Protocol (ICMP) messages, such as by sending ping messages in real time. For example, P-CSCF unreachability can include: P-CSCF unreachability due to link failure or congestion from the P-GW to the P-CSCF, or P-CSCF network element failure, etc.

[0177] 507: The P-GW sends a session establishment response message to the S-GW, indicating that the P-CSCF is unreachable.

[0178] The P-GW sends a Create Session Response message to the S-GW, carrying a specific error code, such as the first error code, to indicate that the P-CSCF is unreachable.

[0179] Optionally, the session establishment response message may carry a first duration or a timer, such as a first timer, to indicate the retry period for the UE to re-access the IMS network. This means that the UE needs to periodically attempt to access the IMS network according to the first duration or the duration indicated by the timer until successful access. The duration of the first timer can be the first duration.

[0180] 508: The S-GW sends a session establishment response message to the MME, indicating that the P-CSCF is unreachable.

[0181] The S-GW can forward the session establishment response message received from the P-GW to the MME, carrying the aforementioned error code, as well as optional information such as the first duration or the first timer.

[0182] 509: The MME sends a PDN connection rejection message to the terminal.

[0183] This PDN connection rejection message corresponds to the aforementioned Figure 4 In the first message of the embodiment, the PDN connection rejection message may carry the error code assigned by the P-GW, and optionally carry information such as a first duration or a first timer.

[0184] In one implementation, if the session establishment response message received by the MME does not carry timer information or an indication of a first duration, the MME may, according to a pre-configured policy, carry timer information or an indication of a first duration in the PDN connection rejection message sent to the terminal.

[0185] 510: After the first duration expires or times out, the UE sends a PDN connection request message to the MME to request access to the IMS network.

[0186] Among them, the PDN connection request message sent by the UE to the MME after the first duration expires or times out corresponds to the aforementioned Figure 4 The second message in the embodiment.

[0187] The PDN connection request message carries an IMS APN, indicating that the UE requests access to the IMS domain; the PCO information element carries a P-CSCF address request parameter, indicating that the UE requests a P-CSCF address.

[0188] In one implementation, after receiving a P-CSCF unreachable message, the UE can determine different processing based on its different attach modes. The UE's attach technology can include packet-switched (PS) technology and circuit-switched (CS) technology, specifically including PS mode 1, PS mode 2, CS / PS mode 1, and CS / PS mode 2, etc.

[0189] Among them, PS mode 1 means that the UE only registers for EPS service and the UE's usage is set to "voice-centric";

[0190] PS Mode 2: This means that the UE only registers for EPS service, and the UE's usage is set to "data-centric".

[0191] CS / PS Mode 1: This means that the UE registers for both EPS and non-EPS services at the same time, and the UE's usage is set to "voice-centric".

[0192] CS / PS Mode 2: This means that the UE registers for both EPS and non-EPS services at the same time, and the UE's usage is set to "data-centric".

[0193] Optionally, after receiving a P-CSCF unreachable message, the UE can determine different processing based on the different attachment modes of the UE, as shown below.

[0194] For UEs with attachment modes PS mode 1 and PS mode 2, after determining that P-CSCF is unreachable, the UE does not attempt CS fallback, but instead waits for the timer to expire before retrying to access the IMS network.

[0195] For UEs with attachment modes of CS / PS mode 1 and CS / PS mode 2, after receiving the P-CSCF unreachable error code, they first attempt to access the CS network. If it is determined that there is no available CS network, they can periodically retry accessing the IMS network according to the first duration or the first timer until they successfully access the IMS network.

[0196] Example 2: Applied to 5G networks, combined with Figure 1 As shown, the network device is AMF as an example.

[0197] like Figure 6 As shown, the communication method includes the following steps.

[0198] 601: The UE powers on and establishes a default PDU session with the 5G core network.

[0199] 602: The UE sends a PDU session establishment request message to the AMF, requesting access to the IMS network.

[0200] The PDU session establishment request message may carry an ePCO information element to indicate the request for a P-CSCF address.

[0201] 603: AMF should be selected as SMF.

[0202] 604: AMF sends a PDU session context creation request message to SMF.

[0203] Specifically, the AMF selects the appropriate SMF and sends a PDU session context creation request (such as PDU Session Create SMContext Request) message to the SMF to request the creation of the PDU session context.

[0204] Optionally, after receiving the PDU session context creation request, the SMF can obtain the subscription data from the UDM and return a response indicating that the context corresponding to the PDU session has been established.

[0205] 605: SMF selects P-CSCF, confirming that P-CSCF is unreachable.

[0206] After receiving the PDU session context creation request, the SMF can obtain the address of an available P-CSCF from the NRF and determine that the P-CSCF is unreachable.

[0207] Specifically, the process by which the SMF determines that the P-CSCF is unreachable can include the following methods:

[0208] (1) The P-CSCF periodically registers with the NRF. The NRF can determine whether there is an available P-CSCF, so the SMF can request the NRF to determine that the P-CSCF is unreachable.

[0209] (2) After the SMF obtains the list of accessible P-CSCF addresses through the NRF, it can save it locally and perform IP reachability detection on the P-CSCF, thereby determining that the P-CSCF is unreachable.

[0210] (3) The SMF may also receive notification messages from other network elements, such as the UPF. When the UPF detects that the P-CSCF is unreachable, the UPF can notify the SMF of the P-CSCF unreachability via the N4 interface message. Alternatively, the AMF can detect that the P-CSCF is unreachable and notify the SMF of the P-CSCF unreachability.

[0211] 606: SMF sends a PDU session context creation response message to AMF, P-CSCF unreachable.

[0212] The PDU session context creation response message is used to indicate that the P-CSCF is unreachable. It can correspond to the third message described in the foregoing embodiments, which is used to indicate to the mobility management device that the P-CSCF is unreachable.

[0213] For example, the PDU session context creation response message may carry a specific error code, such as the first error code, to indicate that the P-CSCF is unreachable.

[0214] Optionally, the PDU session context creation response message may also carry a first duration, or a timer, such as a first timer, to indicate the retry period for the UE to re-access the IMS network. This means that the UE needs to periodically attempt to access the IMS network according to the first duration or the duration indicated by the timer, until successful access. The duration of the first timer can be the first duration.

[0215] 607: The AMF sends a PDU session establishment rejection message to the UE, indicating that the P-CSCF is unreachable.

[0216] Specifically, the PDU session establishment rejection message can carry the aforementioned error code, as well as optional information such as a first duration or a first timer.

[0217] 608: After the first duration expires or times out, the UE sends a PDU session establishment request message to the AMF to request access to the IMS network.

[0218] Among them, after the first duration expires or times out, the PDU session establishment request message sent by the UE to the AMF corresponds to the aforementioned Figure 4 The second message in the embodiment.

[0219] The ePCO information element carried in the PDU session establishment request message contains a P-CSCF address request parameter, indicating that the UE requests a P-CSCF address.

[0220] The various embodiments mentioned above in this application can be combined without contradiction, and no limitation is imposed.

[0221] The above mainly describes the solution provided in this application from the perspective of interaction between various network nodes. Accordingly, this application also provides a communication device, which can be one of the communication devices or nodes in the above method embodiments, or a component such as a chip that can be used in the above communication devices or nodes.

[0222] It is understood that, in order to achieve the aforementioned functions, the communication device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the unit and algorithm operations of the examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0223] It should be understood that the above description is merely an example illustrating the interactions between various network element nodes. In reality, the processing performed by the aforementioned communication devices or nodes is not limited to being performed by a single network element.

[0224] This application can divide the communication device into functional modules based on the above method examples. For example, each function can be divided into its own functional modules, or two or more functions can be integrated into one processing module. The integrated modules can be implemented in hardware or as software functional modules. It is understood that the module division in this application is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0225] For example, when dividing the functional modules using an integrated approach. Figure 7 A schematic diagram of a communication device 700 is shown. The communication device 700 includes an interface module 701.

[0226] In some embodiments, the communication device 700 may further include a storage module. Figure 7 (Not shown in the image) is used to store program instructions and data.

[0227] For example, the communication device 700 can be used to implement the above. Figure 3 The communication device 700 can be described in the embodiment as having the function of a communication device. Figures 4-6 The terminals in the various embodiments described.

[0228] The interface module 701 can be used to receive a first message, which indicates that the proxy session control function is unreachable and indicates a first duration.

[0229] When the first duration expires or the timeout occurs, the interface module 701 can be used to send a second message, which is used to request access to the proxy session control function.

[0230] In one implementation, the first message includes a first error code, which indicates that the agent session control function is unavailable.

[0231] In one embodiment, the interface module 701 can also be used to send the second message to the network device when it detects that there is no accessible circuit-switched (CS) network and the first duration expires or times out.

[0232] In one implementation, the first message is a packet data network connection rejection message, and the second message is a packet data network connection request message.

[0233] In one implementation, the first message is a session establishment rejection message, and the second message is a session establishment request message.

[0234] In one implementation, the second message includes first information indicating the address for obtaining the proxy session control function.

[0235] In addition, the communication device 700 can be used to implement the functions implemented by the network device in the above embodiments. Figure 7 A schematic diagram of a communication device 700 is shown. The communication device 700 includes an interface module 701 and a processing module 702. For example, the communication device 700 is as described above. Figure 4 The network device in the embodiments, or, as described above Figure 5 The MME in the embodiments, or, as described above Figure 6 AMF in the embodiments.

[0236] The processing module 702 can be used to determine that the proxy session control function is unreachable.

[0237] The interface module 701 can be used to send a first message to the terminal, the first message being used to indicate that the proxy session control function is unreachable, the first message indicating a first duration, the first duration being used to indicate the waiting time for the terminal to request access to the proxy session control function.

[0238] In one implementation, the first message includes a first error code, which indicates that the proxy session control function is unavailable.

[0239] In one embodiment, the interface module 701 can also be used to receive a third message indicating that the proxy session control function is unreachable. The processing module 702 can be used to determine that the proxy session control function is unreachable based on the third message.

[0240] In one implementation, the third message includes the first duration.

[0241] In one implementation, the communication device 700 may be an Access and Mobility Management Function (AMF) or a Mobility Management Entity (MME).

[0242] In one embodiment, the interface module 701 can also be used to receive a second message from the terminal, the second message being used to request access to the proxy session control function.

[0243] In one implementation, the first message is a session establishment rejection message, and the second message is a session establishment request message.

[0244] In one implementation, the first message is a packet data network connection rejection message, and the second message is a packet data network connection request message.

[0245] In one implementation, the second message includes first information indicating the address for obtaining the proxy session control function.

[0246] In addition, the communication device 700 can be used to implement the functions implemented by the network device in the above embodiments. Figure 7 A schematic diagram of a communication device 700 is shown. The communication device 700 includes an interface module 701 and a processing module 702. For example, the communication device 700 can be the session management function described in the foregoing embodiments, such as the aforementioned... Figure 5 The P-GW in the embodiments, or, as described above Figure 6 SMF in the embodiments.

[0247] The processing module 702 can be used to determine that the proxy session control function is unreachable.

[0248] The interface module 701 can be used to send a third message to the mobility management device, the third message indicating that the agent session control function is unreachable.

[0249] In one implementation, the third message includes a first error code, which indicates that the agent session control function is unavailable.

[0250] In one implementation, the third message includes a first duration, which indicates the waiting time for the terminal to request access to the proxy session control function.

[0251] In one implementation, the mobility management device can be used to receive a third message and determine that the proxy session control function is unreachable based on the third message; then, the mobility management device is used to send a first message to the terminal, the first message indicating that the proxy session control function is unreachable, the first message indicating a first duration, the first duration indicating the waiting time for the terminal to request access to the proxy session control function.

[0252] In one implementation, the session management device is a packet data network (PDN) gateway, and the mobility management device is a mobility management entity (MME).

[0253] In one implementation, the session management device is a session management function (SMF), and the mobility management device is an access and mobility management function (AMF).

[0254] In summary, when the communication device 800 is used to implement the functions performed by the communication device or node in the above embodiments, other functions that the communication device 800 can implement can be referred to the relevant descriptions of any of the embodiments shown above, and will not be elaborated further.

[0255] In a simplified embodiment, those skilled in the art will recognize that the communication device 700 can employ... Figure 3 The form shown. For example, Figure 3 The processor 301 can call computer execution instructions stored in the memory 303 to cause the communication device 300 to execute the method described in the above method embodiment.

[0256] For example, Figure 7 The function / implementation process of the processing module 702 can be achieved through... Figure 3 It is implemented by processor 301 in the system.

[0257] For example, Figure 7 The function / implementation process of interface module 701 can be accessed through... Figure 3 It is implemented using the communication interface 304.

[0258] It is understood that one or more of the above modules or units can be implemented by software, hardware, or a combination of both. When any of the above modules or units are implemented by software, the software exists as computer program instructions and is stored in memory. The processor can be used to execute the program instructions and implement the above method flow. The processor can be built into a SoC (System-on-a-Chip) or ASIC, or it can be a separate semiconductor chip. In addition to the core that executes software instructions for computation or processing, the processor may further include necessary hardware accelerators, such as field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), or logic circuits that implement dedicated logic operations.

[0259] When the above modules or units are implemented in hardware, the hardware can be any one or any combination of a CPU, microprocessor, digital signal processing (DSP) chip, microcontroller unit (MCU), artificial intelligence processor, ASIC, SoC, FPGA, PLD, application-specific digital circuit, hardware accelerator, or non-integrated discrete device, which can run the necessary software or perform the above method flow independently of software.

[0260] In one possible implementation, this application also provides a chip system, including: at least one processor and an interface, wherein the at least one processor is coupled to a memory via the interface, and when the at least one processor executes a computer program or instructions in the memory, the method in any of the above method embodiments is executed. In one possible implementation, the chip system further includes a memory. Optionally, the chip system may be composed of chips or may include chips and other discrete devices; this application does not specifically limit this.

[0261] Optionally, this application also provides a computer-readable storage medium. All or part of the processes in the above method embodiments can be implemented by a computer program instructing related hardware. This program can be stored in the aforementioned computer-readable storage medium. When executed, the program can include the processes described in the above method embodiments. The computer-readable storage medium can be an internal storage unit of the communication device in any of the foregoing embodiments, such as the hard disk or memory of the communication device. The aforementioned computer-readable storage medium can also be an external storage device of the communication device, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the communication device. Further, the aforementioned computer-readable storage medium can include both internal storage units and external storage devices of the communication device. The aforementioned computer-readable storage medium is used to store the aforementioned computer program and other programs and data required by the communication device. The aforementioned computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0262] In one possible implementation, this application also provides a computer program product. All or part of the processes in the above method embodiments can be executed by a computer program instructing related hardware. This program can be stored in the above computer program product, and when executed, it can include the processes of the above method embodiments.

[0263] In one possible implementation, this application also provides computer instructions. All or part of the processes in the above method embodiments can be executed by computer instructions instructing related hardware (such as a computer, processor, network device, or terminal device). The program can be stored in the aforementioned computer-readable storage medium or the aforementioned computer program product.

[0264] In one possible implementation, this application also provides a communication system, including: the terminal in the above embodiments and a network device, wherein, for example, the network device may be a mobility management device.

[0265] In one possible implementation, the communication system may also include the session management device described in the above embodiments.

[0266] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0267] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0268] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0269] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0270] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method characterized by comprising: The method comprises: receiving a first message, the first message being used for indicating that a proxy session control function is unreachable, the first message indicating a first time length; when the first time length expires or times out, sending a second message, the second message being used for requesting to access the proxy session control function.

2. The method of claim 1, wherein, The first message comprises a first error code, the first error code being used for indicating that the proxy session control function is unreachable.

3. The method according to claim 1 or 2, characterized in that, The sending of the second message comprises: detecting that there is no circuit switched (CS) network that can be accessed, and sending the second message to a network device after the first time length expires or times out.

4. The method according to any one of claims 1 to 3, characterized in that, The first message is a packet data network (PDN) connection reject message, and the second message is a PDN connection request message.

5. The method according to any one of claims 1 to 3, characterized in that, The first message is a session establishment reject message, and the second message is a session establishment request message.

6. The method according to any one of claims 1 to 5, characterized in that, The second message comprises first information, the first information being used for indicating an address of the proxy session control function.

7. A communication method characterized by comprising: The method applied to a mobility management device comprises: determining that a proxy session control function is unreachable; sending a first message to a terminal, the first message being used for indicating that the proxy session control function is unreachable, the first message indicating a first time length, the first time length being used for indicating a waiting time length for the terminal to request to access the proxy session control function.

8. The method of claim 7, wherein, The first message comprises a first error code, the first error code being used for indicating that the proxy session control function is unreachable.

9. The method according to claim 7 or 8, characterized in that, The determining that the proxy session control function is unreachable comprises: receiving a third message, the third message being used for indicating that the proxy session control function is unreachable; determining that the proxy session control function is unreachable according to the third message.

10. The method of claim 9, wherein, The third message comprises the first time length.

11. The method according to any one of claims 7-10, characterized in that, The mobility management device is an access and mobility management function (AMF) or a mobility management entity (MME).

12. The method according to any one of claims 7-10, characterized in that, The method further comprises: receiving a second message from the terminal, the second message being used for requesting to access the proxy session control function.

13. The method of claim 12, wherein, The first message is a session establishment reject message, and the second message is a session establishment request message.

14. The method of claim 12, wherein, The first message is a PDN connection reject message, and the second message is a PDN connection request message.

15. The method according to any one of claims 12-14, characterized in that, The second message comprises first information, the first information being used for indicating an address of the proxy session control function.

16. A method of communication, comprising: The method comprises: a session management device determining that a proxy session control function is unreachable; sending a third message to a mobility management device, the third message being used for indicating that the proxy session control function is unreachable.

17. The method of claim 16, wherein, The third message comprises a first error code, the first error code being used for indicating that the proxy session control function is unreachable.

18. The method according to claim 16 or 17, characterized in that, The third message comprises a first time length, the first time length being used for indicating a waiting time length for a terminal to request to access the proxy session control function.

19. The method according to any one of claims 16-18, characterized by, The method further comprises: a mobility management device receiving the third message and determining that the proxy session control function is unreachable according to the third message; The mobility management device sends a first message to the terminal, the first message being used to indicate that the proxy session control function is unreachable, the first message indicating a first time length, the first time length being used to indicate a waiting time length for the terminal to request to access the proxy session control function.

20. The method according to any one of claims 16-19, characterized by, The session management device is a packet data network (PDN) gateway, and the mobility management device is a mobility management entity (MME).

21. The method according to any one of claims 16-19, characterized by, The session management device is a session management function (SMF), and the mobility management device is an access and mobility management function (AMF).

22. A communications device, characterized by A method as claimed in any one of claims 1-6, 7-15 or 16-21.

23. A communications device, characterized by Comprising: at least one processor coupled with a memory for storing programs or instructions which, when executed by the at least one processor, cause a method as claimed in any one of claims 1-6 to be performed; or cause a method as claimed in any one of claims 7-15 to be performed; or cause a method as claimed in any one of claims 16-21 to be performed.

24. A computer readable storage medium having stored thereon a computer program or instructions, characterized in that, The computer programs or instructions, when executed, cause a method as claimed in any one of claims 1-6 to be performed; or cause a method as claimed in any one of claims 7-15 to be performed; or cause a method as claimed in any one of claims 16-21 to be performed.

25. A computer program product, comprising computer program code in said computer program product, characterised in that, The computer programs or instructions, when executed, cause a method as claimed in any one of claims 1-6 to be performed; or cause a method as claimed in any one of claims 7-15 to be performed; or cause a method as claimed in any one of claims 16-21 to be performed.

26. A chip, characterized by The chip is used to implement a method as claimed in any one of claims 1-6, or to implement a method as claimed in any one of claims 7-15, or to implement a method as claimed in any one of claims 16-21.

27. A communication system, characterized by The communication system comprises: a communication device implementing a method as claimed in any one of claims 1-6, a communication device implementing a method as claimed in any one of claims 7-15, and a communication device implementing a method as claimed in any one of claims 16-21.

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