Communication method and apparatus

Abstract

The present application relates to the technical field of communications. Provided are a communication method and apparatus, which are used for solving the problem of it being impossible for a terminal to use a voice service when an IMS network has a fault. The method comprises: a terminal receiving a first message, wherein the first message is used for indicating that a proxy call session control function is unreachable, and the first message indicates a first duration; and when the first duration expires or times out, the terminal sending a second message, wherein the second message is used for requesting access to the proxy call session control function.

Description

Communication method and apparatus

[0001] The present application claims priority from the Chinese patent application No. 202411254674.4 filed on September 6, 2024, and entitled "A communication method and apparatus", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, and in particular to a communication method and apparatus. BACKGROUND

[0003] With the development of mobile communication technology, the internet protocol multimedia subsystem (IMS) technology emerges as the times require, and gradually replaces the circuit switched (CS) call technology of the traditional second generation (2G) or third generation (3G) network. Among them, the IMS can be carried on the fourth generation (4G) or fifth generation (5G) network to realize voice control, respectively called voice over long term evolution (VoLTE) and voice over new radio (VoNR). VoLTE or VoNR can provide shorter connection for user equipment (UE) to provide high-definition voice.

[0004] At present, the CS network and the IMS network are deployed together. When the UE initiates a voice call in the 4G or 5G network, in the case of IMS network failure or voice call failure, etc., the circuit switched fallback (CSFB) can be used, so that the UE can access the 2G or 3G network, realize voice call through the CS network, and then access the 4G or 5G network after the voice call is over.

[0005] However, the CS network is facing many problems such as old equipment, old underlying architecture, high operation and maintenance cost, etc. In the future, the CS network will be gradually retired or closed. Therefore, after the CS network is not available, the terminal may not be able to normally use voice services in the case of IMS network failure, and the user experience is poor. SUMMARY

[0006] The present application provides a communication method and apparatus to solve the problem that the terminal cannot use voice services in the case of IMS network failure.

[0007] In a first aspect, a communication method is provided, which can be performed by a communication device, which can be a terminal, or a module (such as a chip, chip system or circuit) in the terminal, or a module or software that can realize all or part of the functions of the terminal. The method comprises: receiving a first message, the first message being used to indicate that a proxy session control function is unreachable, the first message indicating a first time length; and when the first time length expires or times out, sending a second message, the second message being used to request access to the proxy session control function.

[0008] In the above embodiment, the network device sends the first message to the terminal, so that the terminal can determine that the proxy session control function of the current IMS network is unreachable, and the terminal can reattempt to access the proxy session control function, i.e., re-request access to the IMS network, after a certain time length according to the notification message. Optionally, the terminal can periodically request access to the IMS network according to the specified time length until successfully accessing the IMS network and realizing communication services through the IMS network, so as to effectively solve the problem of temporary unreachability of the proxy session control function in the IMS network, improve communication efficiency and improve user experience by instructing the terminal to re-request access to the IMS network.

[0009] In an embodiment, the first message comprises a first error code, which is used to indicate that the proxy session control function is unreachable.

[0010] In the above embodiment, the terminal can determine that the proxy session control function of the current IMS network is unreachable through the first error code carried in the received first message, so as to trigger re-request access to the proxy session control function after a first time length.

[0011] In an embodiment, sending the second message to the network device comprises: detecting that there is no accessible circuit switched (CS) network, and sending the second message to the network device when the first time length expires or times out.

[0012] In the above embodiment, when the proxy session control function of the IMS network is unreachable, the terminal can detect whether there is an accessible CS network, and if there is an accessible CS network, the terminal can realize voice call services through the CS technology; if there is no accessible CS network, the terminal can re-request access to the IMS network after a specified time length to realize voice call services.

[0013] In an embodiment, the first message is a packet data network connection reject message, and the second message is a packet data network connection request message.

[0014] The above-mentioned embodiments of the present application can be applied to a 4G network. 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. Therefore, the terminal can re-send a packet data network connection request message to the network after the expiration or timeout of the first time length to request access to the proxy session control function.

[0015] In an embodiment, the first message is a session setup rejection message, and the second message is a session setup request message.

[0016] The above-mentioned embodiments of the present application can be applied to a 5G network. The network can indicate to the terminal that the proxy session control function in the IMS network is unreachable through a session setup rejection message. Therefore, the terminal can re-send a session setup request message to the network after the expiration or timeout of the first time length to request access to the proxy session control function.

[0017] In an embodiment, the second message includes first information, and the first information indicates to obtain the address of the proxy session control function.

[0018] In a second aspect, a communication method is provided. The method can be performed by a communication apparatus. The communication apparatus can be a network device, or a module (such as a chip, a chip system, or a circuit) in the network device, or a module or software that can realize all or part of the functions of the network device. For example, the communication apparatus can be a mobility management device. The method includes determining that a proxy session control function is unreachable, and sending a first message to a terminal. The first message is used to indicate that the proxy session control function is unreachable. The first message indicates a first time length. The first time length is used to indicate a waiting time length for the terminal to request access to the proxy session control function.

[0019] In the above-mentioned embodiments, when the network device determines that the proxy session control function of the IMS network is unreachable, the network device can send a first message to the terminal to indicate that the proxy session control function of the current IMS network is unreachable. Therefore, the terminal can re-attempt to access the proxy session control function, i.e., re-request to access the IMS network, after the expiration of the time length. Optionally, the terminal can periodically request to access the IMS network according to the specified time length until successfully accessing the IMS network to implement a communication service through the IMS network. Therefore, the problem of temporary unreachability of the proxy session control function in the IMS network can be effectively solved. By indicating the terminal to re-request to access the IMS network, the communication efficiency is improved and the user experience is improved.

[0020] In an embodiment, the first message includes a first error code. The first error code is used to indicate that the proxy session control function is unreachable.

[0021] In an embodiment, determining that the proxy session control function is unreachable comprises: receiving a third message, the third message being used to indicate that the proxy session control function is unreachable; and determining that the proxy session control function is unreachable according to the third message.

[0022] In the above embodiments, the mobility management device in the network can autonomously determine that the proxy session control function is unreachable, or can determine that the proxy session control function is currently unreachable according to an indication of a third message received from another network element, that is, the mobility management device can flexibly determine that the proxy session control function in the IMS network is unreachable.

[0023] In an embodiment, the third message comprises the first time length.

[0024] In the above embodiments, the mobility management device can receive the third message and obtain the first time length from the third message, that is, the mobility management device can obtain the waiting time length for the terminal to re-request access to the proxy session control function from another network element. Alternatively, if the first time length is not included in the third message, the mobility management device can determine the waiting time length for the terminal to re-request access to the proxy session control function according to pre-configuration or protocol agreement.

[0025] In an embodiment, the mobility management device is an access and mobility management function (AMF) or a mobility management entity (MME).

[0026] In the above embodiments, the above embodiments of the present application can be applied to a 4G network or a 5G network. For the 4G network, 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 the 5G network, 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 re-send a session establishment request message to the network to request access to the proxy session control function after the first time length expires or times out.

[0027] In an embodiment, the method further comprises: receiving a second message from the terminal, the second message being used to request access to the proxy session control function.

[0028] In the above embodiments, after the mobility management device indicates to the terminal that the current access proxy session control function, the subsequent mobility management device can also receive a request message, such as the second message, from the terminal to access the proxy session control function, thereby improving the efficiency of the terminal successfully accessing the proxy session control function to implement communication services through the IMS network and improving communication efficiency and user experience.

[0029] In an embodiment, the first message is a session establishment rejection message, and the second message is a session establishment request message.

[0030] In an embodiment, the first message is a packet data network connection reject message, and the second message is a packet data network connection request message.

[0031] In an embodiment, the second message comprises first information, the first information indicating to obtain an address of the proxy session control function.

[0032] In a third aspect, a communication method is provided, which can be performed by a communication apparatus. The communication apparatus can be a network device, or a module (e.g., a chip, a chip system, or a circuit) in the network device, or a module or software that can implement all or part of the functions of the network device. For example, the communication apparatus can be a session management device, and the method comprises: determining, by the session management device, that a proxy session control function is unreachable; and sending, by the session management device, a third message to a mobility management device, the third message being used to indicate that the proxy session control function is unreachable.

[0033] In an embodiment, the third message comprises a first error code, the first error code being used to indicate that the proxy session control function is unreachable.

[0034] In an embodiment, the third message comprises a first time length, the first time length being used to indicate a waiting time length of the terminal for accessing the proxy session control function.

[0035] In an embodiment, the method further comprises: receiving, by the mobility management device, the third message, and determining, by the mobility management device, that the proxy session control function is unreachable according to the third message; and sending, by the mobility management device, a first message to a terminal, the first message being used to indicate that the proxy session control function is unreachable, and the first message indicating a first time length, the first time length being used to indicate a waiting time length of the terminal for accessing the proxy session control function.

[0036] In an embodiment, the session management device is a packet data network (PDN) gateway, and the mobility management device is a mobility management entity (MME).

[0037] In an embodiment, the session management device is a session management function (SMF), and the mobility management device is an access and mobility management function (AMF).

[0038] In a fourth aspect, a communication apparatus is provided, which can be used to implement the method described above. The communication apparatus can be an apparatus that performs the method of the first aspect, the second aspect, or the third aspect, or a node or device that comprises the apparatus, or a module (e.g., a chip, a chip system, or a circuit) in the apparatus, or a logic node, a logic module, or software that can implement part or all of the functions.

[0039] The apparatus includes modules, units, or means corresponding to the above-described methods, which can be implemented by hardware, software, or by a combination of hardware and software. The hardware or software includes one or more modules or units corresponding to the above-described functions.

[0040] In a possible implementation, the apparatus can include a processing module and a transceiver module. The processing module can be configured to implement the processing functions in any of the above aspects and any possible implementation thereof. The processing module can be, for example, a processor. The transceiver module, which can also be referred to as a transceiver unit, is configured to implement the functions of transmitting and / or receiving in any of the above aspects and any possible implementation thereof. The transceiver module can include a transceiver circuit, a transceiver, a transceiver, or a communication interface.

[0041] In a possible implementation, the transceiver module includes a transmitting module and a receiving module, which are configured to implement the functions of transmitting and receiving in any of the above aspects and any possible implementation thereof.

[0042] In a fifth aspect, a communication apparatus is provided, which includes a processor. The processor is configured to couple with a memory, read instructions in the memory, and execute the method in any of the above aspects according to the instructions. The communication apparatus can be the apparatus in the first aspect, the second aspect, or the third aspect, or a node or device including the apparatus, or a module in the apparatus, such as a chip, a chip system, or a circuit, or a logical node, a logical module, or software that can implement some or all of the functions.

[0043] In a possible implementation, the communication apparatus further includes a memory configured to store program instructions and / or data. Optionally, the memory and the processor are integrated together.

[0044] In a possible implementation, the communication apparatus is a chip or a chip system. Optionally, when the communication apparatus is a chip system, the chip system can be composed of a chip or can include a chip and other discrete devices.

[0045] In a sixth aspect, a communication apparatus is provided, which includes a processor and an interface circuit. The interface circuit is configured to receive a computer program or instructions and transmit the computer program or instructions to the processor. The processor is configured to execute the computer program or instructions to enable the communication apparatus to perform the method in any of the above aspects. The communication apparatus can be the apparatus in the first aspect, the second aspect, or the third aspect, or a node or device including the apparatus, or a module in the apparatus, such as a chip, a chip system, or a circuit, or a logical node, a logical module, or software that can implement some or all of the functions.

[0046] In a possible implementation, the communication apparatus is a chip or a chip system. Optionally, when the communication apparatus is a chip system, the chip system can be composed of a chip or can include a chip and other discrete devices.

[0047] 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 method of any of the above aspects.

[0048] In an eighth aspect, a computer program product is provided, which stores instructions that, when executed on a computer, cause the computer to perform the method of any of the above aspects.

[0049] In a ninth aspect, a communication system is provided, which includes a terminal that performs the method of the first aspect and a network device that performs the method of the second aspect. For example, the network device that performs the method of the second aspect can be a mobility management device.

[0050] In a possible implementation, the communication system includes a communication apparatus that performs the method of the third aspect. For example, the communication apparatus that performs the method of the third aspect can be a session management device.

[0051] The technical effects brought by any of the possible implementations of the second aspect to the ninth aspect can refer to the technical effects brought by the different possible implementations of the first aspect, which will not be described herein.

[0052] It can be understood that the solutions in the above aspects can be combined as long as the solutions are not contradictory. BRIEF DESCRIPTION OF DRAWINGS

[0053] FIG. 1 is a schematic diagram of an architecture of a communication system according to an embodiment of the present application;

[0054] FIG. 2 is a schematic diagram of another architecture of a communication system according to an embodiment of the present application;

[0055] FIG. 3 is a schematic diagram of a structure of a communication apparatus according to an embodiment of the present application;

[0056] FIG. 4 is a schematic diagram of a flow of a communication method according to an embodiment of the present application;

[0057] FIG. 5 is a schematic diagram of a flow of another communication method according to an embodiment of the present application;

[0058] FIG. 6 is a schematic diagram of a flow of another communication method according to an embodiment of the present application;

[0059] FIG. 7 is a schematic diagram of a structure of another communication apparatus according to an embodiment of the present application. DETAILED DESCRIPTION

[0060] Hereinafter, the terms "first", "second", etc. are used only for the purpose of description, and should not be construed as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0061] It should be noted that in this application, the words "exemplary" or "for example" are used to mean serving as an example, instance, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of "exemplary" or "for example" is intended to present concepts in a particular manner. It should be noted that the terms "first", "second", etc. are used only for the purpose of description, and should not be construed as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0062] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0063] First, the implementation environment and application scenario of the embodiments of the present application are briefly introduced.

[0064] The communication method provided by the embodiments of the present application can be applied to a fourth generation (4th generation, 4G) communication system, such as a long term evolution (long term evolution, LTE) communication system or an evolved packet system (Evolved Packet System, EPS) network, and can also be applied to a fifth generation (5th generation, 5G) communication system, such as a 5G new radio (new radio, NR) communication system, or to various communication systems evolved after 5G, future communication systems. The 4G core network is called evolved packet core network (Evolved Packet Core, EPC), and the 5G core network is called 5G core network (5G Core, 5GC).

[0065] Exemplarily, FIG. 1 shows a network architecture to which the present application is applicable, wherein FIG. 1 shows the interaction relationship between network functions (NFs) and entities and the corresponding interfaces taking the network service architecture of a 5G system as an example. The 3rd generation partnership project (3GPP) service-based architecture (SBA) of the 5G system contains network functions and entities mainly including: a user equipment (UE), at least one access network (AN) or radio access network (RAN) node, a user plane function (UPF), a data network (DN), an access and mobility management function (AMF), a session management function (SMF), a policy control function (PCF), an application function (AF), a unified data management (UDM), a network exposure function (NEF), a unified data repository (UDR), an authentication server function (AUSF), an NF repository function (NRF), a network slice selection function (NSSF), a network slice specific authentication and authorization function (NSSAAF), and a network data analytics function (NWDAF), etc.

[0066] Among them, the UE, (radio) access network ((R)AN) node, UPF and DN are generally referred to as user plane network functions and entities (or user plane network elements), and other parts are generally referred to as control plane network functions and entities (or control plane network elements). The control plane network element is defined by 3GPP as a processing function in a network, and the control plane network element has a 3GPP-defined function behavior and a 3GPP-defined interface. NF can be a network element running on a dedicated hardware, or a software instance running on a dedicated hardware, or a virtual function instantiated on a suitable platform, such as a cloud infrastructure.

[0067] The main functions of each network function are described below.

[0068] Among them, the user plane network functions in the communication system include:

[0069] (R)AN node: (R)AN can be AN, RAN, access network device, RAN entity or access node, etc., which constitutes a part of the communication system and helps the terminal device to access the communication network. For example, (R)AN can be various forms of base stations, such as macro base stations, micro base stations, radio controllers, relay stations, access points, or vehicle-mounted devices, wearable devices, or network devices in future evolved public land mobile networks (PLMN), etc. (R)AN is mainly responsible for radio resource management, quality of service management, data compression and encryption, etc.

[0070] In addition, the (R)AN node can also be an open access network (open RAN, O-RAN or ORAN), a cloud radio access network (CRAN), or an access node in a wireless fidelity (WiFi) system, and can also be an access node in a communication system that integrates two or more of the above systems.

[0071] In a possible scenario, the RAN node can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a base station in a future mobile communication system (next generation NodeB, gNB), or an access node in a WiFi system, etc. The RAN node can be a macro base station, a micro base station or an indoor station, a relay node or a donor node, or a wireless controller in a CRAN scenario. Optionally, the RAN node can also be a server, a wearable device, a vehicle or a vehicle-mounted device, etc. For example, the access network device in vehicle to everything (V2X) technology can be a road side unit (RSU). All or part of the functions of the RAN node in the present application can also be implemented by software functions running on hardware, or by virtualized functions instantiated on a platform such as a cloud platform. The RAN node in the present application can also be a logical node, a logical module or software that can implement all or part of the functions of the RAN node.

[0072] In another possible scenario, multiple RAN nodes cooperate to assist a terminal device to implement wireless access, and different RAN nodes respectively implement part of the functions of a base station. For example, the RAN node can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), etc. The CU and the DU can be separately arranged, or can be included in the same network element, such as a baseband unit (BBU). The RU can be included in a radio frequency device or a radio frequency unit, such as a radio frequency remote unit (RRU), an active antenna processing unit (AAU), or a remote radio head (RRH).

[0073] The CU (or CU-CP and CU-UP), DU or RU can also have different names in different systems, but those skilled in the art can understand their meanings. For example, in the ORAN system, the CU can also be referred to as O-CU (open CU), the DU can also be referred to as O-DU, the CU-CP can also be referred to as O-CU-CP, the CU-UP can also be referred to as O-CU-UP, and the RU can also be referred to as O-RU. For the convenience of description, the CU, CU-CP, CU-UP, DU and RU are taken as examples for description in this application. Any one of the CU (or CU-CP, CU-UP), DU and RU in this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0074] UE: can also be referred to as a terminal, a terminal device, a mobile station (MS), a mobile terminal (MT), etc., or a device used to provide voice or data connectivity to a user, or an Internet of Things device. For example, a terminal device includes a handheld device having wireless connection functionality, a vehicle-mounted device, etc. At present, a terminal device can be: a mobile phone, a tablet computer, a notebook computer, a palm computer, a mobile Internet device (MID), a wearable device (such as a smart watch, a smart bracelet, a pedometer, smart glasses, etc.), a vehicle-mounted device (such as a car, a bicycle, an electric vehicle, an airplane, a ship, a train, a high-speed rail, etc.), a satellite terminal, a virtual reality (VR) device, an augmented reality (AR) device, a smart point of sale (POS) machine, a customer-premises equipment (CPE), a light UE, a reduced capability UE (REDCAP UE), a wireless terminal in industrial control, a smart home device (such as a refrigerator, a television, an air conditioner, an electricity meter, etc.), a smart robot, a mechanical arm, a workshop device, a wireless terminal in unmanned driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, or a wireless terminal in a smart home, a flight device (such as a smart robot, a hot air balloon, a drone, an airplane), etc. A terminal device can also be a vehicle device, such as a whole vehicle device, a vehicle-mounted module, a vehicle-mounted chip, an on board unit (OBU), or a telematics box (T-BOX), etc. A terminal device can also be other devices with terminal functions, for example, a device that plays a terminal function in D2D communication.

[0075] Embodiments of the present application do not limit the device form of the terminal, and the device used to implement the function of the terminal device can be a terminal device, or can be a device capable of supporting the terminal device to implement the function, such as a chip system. The device can be installed in the terminal device or used in matching with the terminal device. In embodiments of the present application, a chip system can be composed of a chip, or can include a chip and other discrete devices. All or part of the functions of the terminal device in the present application can also be implemented by software functions running on hardware, or by virtualized functions instantiated on a platform (such as a cloud platform).

[0076] UPF: mainly responsible for forwarding and receiving user plane data. The UPF can receive downlink data from the DN and then transmit the downlink data to the UE through the (R)AN. The UPF can also receive uplink data from the UE through the (R)AN and then forward the uplink data to the DN.

[0077] DN: for example, the DN can be an operator service network, an Internet access, or a third-party service network, etc. The DN can interact with the UE through a PDU session. Among them, the PDU session can be divided into multiple types, such as internet protocol version 4 (IPv4), IPv6, etc. For the 5GC network, the IMS network is a kind of DN.

[0078] In addition, the control plane network functions in the communication system include:

[0079] AMF: mainly responsible for processing control plane messages, responsible for mobility management of terminal devices, including mobile state management, allocation of user temporary identity, authentication and authorization of users. For example, access control, mobility management, registration and deregistration, and network element selection, etc.

[0080] SMF: mainly used for session management, session establishment, (private) IP address allocation and management of the UE, responsible for the establishment, modification and release of the session, as well as quality of service (QoS) control, etc.

[0081] UDM: mainly used for authentication credit processing, responsible for managing subscription data, user identity processing, access authorization, registration / mobility management, subscription management and short message management, etc. For example, when the subscription data of the user is modified, the UDM is responsible for notifying the corresponding network element.

[0082] NEF: mainly used for providing corresponding security guarantees to ensure the security of external applications to the communication network, providing external application QoS customization capability exposure, mobility state event subscription, AF request distribution, etc.

[0083] NRF: mainly used for providing internal / external addressing functions, etc.

[0084] AUSF: mainly used for authentication processing functions, realizing bidirectional authentication and authorization between the terminal and the network, etc.

[0085] AF: mainly used for sending application impact data routing information to the network side, interacting with the policy framework through the network exposure function network element for policy control, etc.

[0086] PCF: the main function is a policy decision point, provides rules such as detection based on service data flow or application, QoS and flow-based charging control. And can provide policy to AMF, SMF, such as QoS policy, slice selection policy, etc.

[0087] Further, the IMS network can be carried on a 4G or 5G network, etc., to provide voice call services based on the Internet Protocol (Internet Protocol, IP).

[0088] The IMS network can include a call session control function (Call Session Control Function, CSCF), which is mainly responsible for processing signaling control in the process of a multimedia call session, such as can be used to manage user authentication of the IMS network, IMS bearer QoS, and other network entities. Control of the Session Initiation Protocol (SIP) session, as well as service negotiation and resource allocation, etc.

[0089] Among them, according to the different functions of CSCF, it can be divided into proxy CSCF (Proxy CSCF, P-CSCF), interrogating CSCF (Interrogating CSCF, I-CSCF), and serving CSCF (Serving CSCF, S-CSCF). In essence, they are all SIP servers and can be used to process SIP signaling. Among them, the main functions of P-CSCF include: forwarding the SIP registration request sent by the terminal to I-CSCF; forward the SIP message sent by the terminal to S-CSCF, and determine the S-CSCF by the P-CSCF when the terminal initiates the registration process. P-CSCF is the user access node of the IMS network.

[0090] Optionally, as shown in FIG. 1, the IMS network can include at least one proxy session control function (Proxy-Call Session Control Function, P-CSCF).

[0091] In addition, Figure 2 shows another network architecture to which the present application is applicable, and Figure 2 takes the network service architecture of a 4G system as an example. The network functions and entities included in the 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.

[0092] Among them, MME: the key control node of the LTE access network, which is responsible for the positioning of the UE (User Equipment) in idle mode, paging process, including relay.

[0093] S-GW: the user plane access service gateway of the EPC network, which is responsible for user data forwarding.

[0094] P-GW: used to provide session management and bearer control for users, data forwarding, IP address allocation, and non-3GPP user access functions. It is the anchor point for user access to the Packet Data Network (PDN).

[0095] HSS: used to process information including: user identification, numbering and address information; user security information; user positioning information; user list information.

[0096] PCRF: can control the QoS (Quality of Service) of users and services, thereby providing differentiated services for users, and providing traffic bearing resources for users and traffic charging policies, such as Policy and Charging Control (PCC) rules.

[0097] 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.

[0098] It should be noted that the functions of other network elements included in FIG. 1 or FIG. 2 can refer to the related description in the conventional technology, which will not be repeated here. The network architecture shown in FIG. 1 or FIG. 2 is only used for example, and is not used to limit the technical solutions of the present application. Those skilled in the art should understand that in the specific implementation process, other network elements or devices can also be included, and the number of access network devices, terminal devices and / or core network devices can also be determined according to specific needs.

[0099] Optionally, each network element shown in FIG. 1 or FIG. 2 can be a device, or a functional module in the device, or a logical functional unit. It can be understood that the above functions can be network elements in hardware devices, such as communication chips in mobile phones, or software functions running on special hardware, or virtualized functions instantiated on a platform (for example, a cloud platform).

[0100] It can be understood that the devices or network elements in the communication system of FIG. 1 or FIG. 2 can communicate directly or through forwarding of other devices, which is not limited in the embodiments of the present application.

[0101] It can be understood that the above FIG. 1 or FIG. 2 is only a schematic diagram, and does not constitute a limitation on the applicable scenarios of the technical solutions provided by the present application. Those skilled in the art should understand that in the specific implementation process, the communication system can include fewer devices or network elements than those shown in FIG. 1 or FIG. 2, or the communication system can also include other devices or other network elements, and the number of devices or network elements in the communication system can also be determined according to specific needs.

[0102] For example, each network element in FIG. 1 or FIG. 2 can be implemented by the communication device 300 in FIG. 3. FIG. 3 shows a hardware structure schematic diagram of a communication device applicable to the embodiments of the present 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 can also include a memory 303.

[0103] The processor 301 can be one or more Central Processing Units (CPUs), which can be a single core processor or a multiple core processor. The processor can be a general purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, and can implement or execute the methods, steps and logical block diagrams disclosed in the embodiments of the present application. The general purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of the present application can be directly embodied as a hardware processor for execution, or a combination of hardware and software modules in the processor for execution.

[0104] Optionally, the processor can include one or a combination of 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 network processor (NPU).

[0105] The communication line 302 can include a path for transmitting information between the above components, such as a bus.

[0106] The communication interface 304 uses any transceiver-like device for communicating with other devices or communication networks, such as an Ethernet interface, a RAN interface, a wireless local area networks (WLAN) interface, etc.

[0107] The memory 303 can include, but is not limited to, a cache, a read-only memory (ROM), a random access memory (RAM), a synchronous dynamic random access memory (SDRAM), a hard disk drive (HDD), or a solid-state drive (SSD), an erasable programmable ROM (EPROM), or a compact disc read-only memory (CD-ROM), and the like. The memory is any medium capable of storing or carrying the desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited thereto. The memory in the embodiments of the present application can also be a circuit or any other device capable of realizing a storage function, used for storing computer programs or instructions, and / or data. Alternatively, the memory can exist independently and be connected to the processor through the communication line 302. Alternatively, the memory can also be integrated with the processor. The memory provided in the embodiments of the present application can generally have a non-volatility. The memory 303 is used to store computer execution instructions related to the schemes of the present application, and the execution is controlled by the processor 301. The processor 301 is used to execute the computer execution instructions stored in the memory 303, so as to realize the method provided in the embodiments of the present application.

[0108] Optionally, the computer execution instructions in the embodiments of the present application can also be referred to as application program codes, which are not specifically limited in the embodiments of the present application.

[0109] In a specific implementation, as an embodiment, the processor 301 can include one or more CPUs, for example, CPU0 and CPU1 in FIG. 3.

[0110] In a specific implementation, as an embodiment, the communication device 300 can include multiple processors, for example, the processor 301 and the processor 307 in FIG. 3. Each of the processors can be a single-CPU processor or a multi-CPU processor. The processor herein can refer to one or more devices, circuits, and / or processing cores for processing data (for example, computer program instructions).

[0111] In a particular implementation, as an example, the communication apparatus 300 can 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 can 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 can be a mouse, a keyboard, a touch screen device, a sensor device, etc.

[0112] The communication apparatus 300 described above can be a general-purpose device or a special-purpose device. In a particular implementation, the communication apparatus 300 can be a laptop computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal apparatus, an embedded device, or a device having a similar structure as shown in FIG. 3. The embodiments of the present application do not limit the type of the communication apparatus 300.

[0113] The communication method provided by the embodiments of the present application will be described in detail below.

[0114] It should be noted that the names of messages between network elements or the names of parameters in the messages in the following embodiments of the present application are only examples, and other names can also be used in a particular implementation, which is not limited in the embodiments of the present application.

[0115] It can be understood that some or all of the steps in the embodiments of the present application are only examples, and other steps or variations of various steps can also be performed in the embodiments of the present application. In addition, the steps can be performed in different orders according to the embodiments of the present application, and it is possible that not all steps in the embodiments of the present application are performed.

[0116] The present application provides a communication method, which can be applied to 4G network, 5G network and future communication network, etc. In the case of IMS network failure, the network can indicate that the current proxy session control function is unreachable to the terminal, so as to instruct the terminal to request access to the proxy session control function after a certain time length, so as to solve the problem of unavailable voice call service in the case of IMS network failure, improve communication efficiency and improve user experience.

[0117] As shown in FIG. 4, the method can include the following steps.

[0118] 401: The network device determines that the proxy session control function is unreachable.

[0119] In an embodiment, the network device can be a network element of the core network, such as a mobility management device. That is, the mobility management device of the core network can perform the subsequent step 402 after determining that the proxy session control function is unreachable. For example, for a 5G network, the mobility management device can be an AMF; for a 4G network, the mobility management device can be an MME.

[0120] In an embodiment, the proxy session control function being unreachable can include that the proxy session control function in the IMS network is faulty, and / or a link between the core network and the proxy session control function is faulty (e.g., the link is disconnected or congested, etc.). That is, the core network is currently unable to establish a connection with the proxy session control function in the IMS network, and thus the network device is unable to implement a communication service (e.g., a voice call service) for the terminal via the IMS network.

[0121] In an embodiment, before step 401, the terminal triggers a proxy session control function discovery procedure, so that the network device can determine that the proxy session control function is unreachable based on the proxy session control function discovery procedure triggered by the terminal. In subsequent embodiments, the proxy session control function discovery procedure of the terminal will be described, and thus will not be described herein.

[0122] For example, the proxy session control function can refer to a P-CSCF in the IMS network.

[0123] In an embodiment, the IMS network can include one or more proxy session control functions, such as multiple P-CSCFs in the IMS network. In this case, the proxy session control function being unreachable can refer to that all of the multiple proxy session control functions are unreachable, or all of the P-CSCFs in the IMS network are unreachable.

[0124] 402: The network device sends a first message to the terminal, and the first message is used to indicate that the proxy session control function is unreachable.

[0125] After determining that the proxy session control function is unreachable, the network device can generate the first message, and the first message is used to indicate that the proxy session control function is unreachable.

[0126] In an embodiment, the first message can carry a specific error code, such as a first error code, and the first error code can be used to indicate that the proxy session control function is unreachable.

[0127] Correspondingly, the terminal receives the first message, and can determine that the proxy session control function in the current IMS network is unreachable based on the first message. For example, the terminal receives the first message, obtains the first error code carried in the first message, and can determine that the proxy session control function is unreachable based on the first error code.

[0128] In addition, the first message can further indicate a first time length, the first time length being used to indicate a waiting time length for the terminal to request the access to the proxy session control function, i.e., the first time length can be a waiting time length for the terminal to re-request the access to the IMS network. That is, the network device can indicate, through the first message, the terminal that the proxy session control function is unreachable, and indicate that the retry waiting time length is the first time length, and the terminal can attempt to request the access to the proxy session control function of the IMS network after the first time length.

[0129] The application does not limit the specific indication manner of the first time length. For example, the first message can include the first time length, such as the first time length being 1 millisecond (ms), and the first message can carry the time length value 1 ms. Alternatively, the network device and the terminal can be pre-configured with parameters of several first time lengths and corresponding indexes, such as the pre-configured values of the first time length can be 1 ms, 2 ms and 5 ms, and the corresponding indexes can be 00, 01 and 11, so that the first message indicates one of the indexes, which can indicate the value of the first time length corresponding to the index.

[0130] In a possible implementation, the network device and the terminal can be pre-configured to periodically re-request the access to the proxy session control function, or the first message sent by the network device to the terminal is used to indicate that the terminal can periodically re-request the access to the proxy session control function, wherein the first time length can be a period of re-accessing the IMS network, i.e., the terminal can trigger the request for the access to the proxy session control function every first time length.

[0131] For example, the terminal can periodically request the access to the proxy session control function after receiving the first message, i.e., the terminal triggers the request for the access to the proxy session control function every first time length until the terminal successfully accesses the proxy session control function. For example, the terminal receives a response message indicating the successful access to the proxy session control function, and the terminal stops the periodic request.

[0132] In another possible implementation, the maximum number of repeated requests for the access to the proxy session control function can be set, such as the network device and the terminal can be pre-configured with the maximum number of times of the periodic re-request for the access to the proxy session control function by the terminal, such as three times or five times; or the first message sent by the network device to the terminal can further be used to indicate the number of times of repetition.

[0133] For example, after receiving the first message, the terminal periodically requests the P-CSCF until the terminal successfully accesses the P-CSCF or until the number of repeated requests reaches the maximum number of times indicated. For example, the maximum number of times is configured to be three, and the terminal receives a response message indicating that the terminal successfully accesses the P-CSCF, or the terminal repeatedly requests the P-CSCF for three times after receiving the first message, and the terminal stops periodically requesting the P-CSCF.

[0134] 403: When the first time period expires or times out, the terminal sends a second message to the network device to request access to the P-CSCF.

[0135] That is, after receiving the first message, the terminal can send the second message to the network device after the first time period.

[0136] In an embodiment, after receiving the first message, the terminal can start a first timer, and the time period of the first timer can be set to the first time period. When the first timer expires or times out, the terminal triggers sending the second message to the network device, and the second message can be used to request access to the P-CSCF.

[0137] In an embodiment, the terminal sends the 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.

[0138] In an embodiment, the second message can include first information, which can be used to indicate the address of the P-CSCF. That is, the network device can carry the first information in the second message to indicate that the terminal requests the address of the P-CSCF.

[0139] In an embodiment, the terminal currently accesses a 4G network, and the first message can be a packet data network connection rejection message (such as a PDN connectivity reject message), and the second message can be a packet data network connection request message (such as a PDN connectivity request message), which is referred to as a PDN connection request message.

[0140] For example, the PDN connection request message can include an indication of an access point name (APN) and a protocol configuration option (PCO). The APN can be used to indicate the access mode of the terminal to connect to the network. The PCO is used to provide additional information for the terminal to connect to the network.

[0141] For example, the APN carried in the PDN connection request message is an IMS APN, indicating that the terminal needs to access the IMS network; the P-CSCF address request (such as P-CSCF Address Request) parameter is included in the PCO information element, that is, the address of the P-CSCF is requested.

[0142] In another embodiment, the terminal currently accesses the 5G network, and the first message can be specifically a session establishment rejection message, and the second message can be specifically a session establishment request message. For example, the first message can be a PDU session establishment rejection message (Session Establishment reject) message, which is used to indicate that the network rejects to establish a PDU session for the terminal; and the second message can be a PDU session establishment request message (Session Establishment Request) message, which is used to request to establish a PDU session.

[0143] For example, the PDU session establishment request message can include an extended protocol configuration option (ePCO), which is used to provide additional information of the terminal connecting the network.

[0144] For example, the ePCO information element carried in the PDU session establishment request message can include the P-CSCF address request (such as P-CSCF Address Request) parameter, that is, the address of the P-CSCF is requested.

[0145] It should be noted that the terminal sends a request to access the P-CSCF to the network device, such as the second message. Optionally, the terminal can periodically send the request until the unavailability of one or more P-CSCFs in the IMS network is resolved, so that the terminal can successfully access the reachable P-CSCF. The specific interaction process can refer to the related technical process. In addition, the process of the terminal successfully accessing the P-CSCF is applied to different network architectures such as 4G or 5G, and the corresponding interaction process can be different, which will not be described herein.

[0146] In one embodiment, after the terminal determines that the P-CSCF is unreachable, the terminal can directly trigger to re-access the P-CSCF; or the terminal can also try to fall back to the CS network, and if there is no accessible CS network, the terminal re-requests to access the P-CSCF.

[0147] That is, in one embodiment, the terminal sends the second message to the network device, which can specifically include: the terminal detects that there is no accessible CS network, and sends the second message to the network device after the first time period expires or times out.

[0148] For example, the terminal detects whether there is an accessible CS network. Specifically, the terminal can initiate an access request of the CS network, for example, the terminal can send a CS service request (e.g., a CM Service Request) message to a mobile access gateway control function (mAGCF), for example, the terminal sends a connect management service request message to the mAGCF. Then, if the terminal does not receive a corresponding response message, the terminal determines that there is no accessible CS network. Conversely, if the terminal receives a corresponding response message, the terminal detects that there is an accessible CS network, and thus can implement a voice call service through the accessible CS network.

[0149] In an embodiment, the network device determines that the proxy session control function is unreachable in the step 401, which can include various implementations. For example, the network device can request other network elements to obtain available proxy session control functions, and thus determine that the proxy session control function is unreachable. Alternatively, the network device can receive a notification message from other network elements, which is used to indicate that the proxy session control function is unreachable.

[0150] For example, the network device is a mobility management device, and before the step 401, the session management device can send a third message to the mobility management device, which is used to indicate that the proxy session control function is unreachable, so that the mobility management device can determine that the proxy session control function is unreachable according to the third message. For example, the session management device in the 5G network can be an SMF, and the session management device in the 4G network can be a PDN gateway. The PDN gateway can send the third message to the MME through the serving gateway S-GW.

[0151] Alternatively, in a possible embodiment, the user plane function can send a third message to the mobility management device, which is used to indicate that the proxy session control function is unreachable.

[0152] For example, if the network device is an SMF, the SMF can determine that the P-CSCF is unreachable in the following ways, for example:

[0153] (1) The P-CSCF can periodically register with the NRF, and the NRF can determine whether there is an available P-CSCF, so that the SMF can request the NRF to determine that the P-CSCF is unreachable.

[0154] (2) After the SMF obtains the list of accessible P-CSCF addresses through the NRF, the SMF can locally save the list and perform IP reachability detection on the P-CSCF, so as to determine that the P-CSCF is unreachable.

[0155] (3) The SMF can also receive a notification message sent by another network element, such as a UPF, to determine that the P-CSCF is unreachable. When the UPF detects that the P-CSCF is unreachable, the UPF can notify the SMF that the P-CSCF is unreachable through an N4 interface message. Alternatively, when the AMF detects that the P-CSCF is unreachable, the AMF can notify the SMF that the P-CSCF is unreachable.

[0156] In the following, the communication method provided by the present application will be described by combining specific embodiments, including a specific implementation of the network device determining that the proxy session control function is unreachable, which will not be described herein again.

[0157] In an implementation, the network device is a mobility management device, and the third message sent by the session management device to the mobility management device can include a first error code, used to indicate that the proxy session control function is unreachable. Thus, the mobility management device can determine, according to the third message, that the proxy session control function is unreachable, and then generate a first message and send the first message to the terminal, used to indicate that the proxy session control function is unreachable.

[0158] Optionally, the third message can include a first time length, which is a waiting time length for the terminal to re-request to access the proxy session control function, or the third message can not include the first time length.

[0159] For example, the third message received by the mobility management device can include the first error code and the first time length. Thus, the mobility management device can determine, according to the third message, that the proxy session control function is unreachable, and then generate a first message according to the third message and send the first message to the terminal. The first message can include the first error code and the first time length, used to indicate that the proxy session control function is unreachable, and the waiting time length for the terminal to re-request to access the proxy session control function is the first time length.

[0160] Alternatively, in another implementation, the third message received by the mobility management device can include the first error code, used to indicate that the proxy session control function is unreachable. Thus, the mobility management device can determine, according to the third message, that the proxy session control function is unreachable, and then generate a first message according to the third message and send the first message to the terminal. The first message can include the first error code and the first time length, used to indicate that the proxy session control function is unreachable, and the waiting time length for the terminal to re-request to access the proxy session control function, indicated by the mobility management device to the terminal, can be the first time length.

[0161] In the above embodiments, when the mobility management device in the network determines that the proxy session control function is unreachable, the terminal can be instructed that the current proxy session control function is unreachable, so that the terminal can reattempt to access the proxy session control function, i.e., re-request to access the IMS network, according to the instruction after a certain time length. Optionally, the terminal can periodically request to access the IMS network until successfully accessing the IMS network, so that the communication service can be implemented through the IMS network. The above embodiments of the present application can effectively solve the problem of temporary unreachability of the proxy session control function in the IMS network, and improve the communication efficiency and user experience by instructing the terminal to re-request to access the IMS network.

[0162] Several possible specific embodiments will be described below in conjunction with the accompanying drawings.

[0163] Embodiment one: applied to a 4G network, and taking the network device MME as an example in conjunction with FIG. 2.

[0164] As shown in FIG. 5, the communication method comprises the following steps.

[0165] 501: The UE is powered on and attached to the network to establish a default bearer of the UE to the APN.

[0166] The above process refers to the attachment process of the UE to the MME after the UE is powered on.

[0167] The process includes establishing a default bearer of the UE to the APN, or a default bearer of the Quality of Service Class Identifier (QCI), i.e., QCI=9.

[0168] 502: The UE sends a PDN connection request message to the MME to request to access the IMS network.

[0169] The APN carried in the PDN connection request message is the IMS APN, indicating that the UE needs to access the IMS domain. In addition, the P-CSCF address request (P-CSCF Address Request) parameter is included in the PCO information element in the PDN connection request message, which is used to indicate the request to obtain the P-CSCF address.

[0170] 503: The MME sends a session establishment request message to the S-GW.

[0171] The session establishment request (such as create session request) message sent by the MME to the S-GW can include a default bearer ID, carry the IMS APN, include the P-CSCF address request parameter in the PCO information element, and include the QoS configuration file (such as QCI=5) of the subscription.

[0172] 504: The S-GW sends a session establishment request message to the P-GW.

[0173] The session establishment request message can carry a PCO information element (P-CSCF address request parameter), a UE IP allocated by the P-GW, and an address of the selected P-CSCF.

[0174] 505: The P-GW obtains PCC rules of the UE from the PCRF.

[0175] Specifically, the PCRF can determine a policy of an EPS session according to a subscription profile, select a rule corresponding to SIP signaling as the PCC rule, and forward the PCC rule to the P-GW.

[0176] 506: The P-GW detects that the P-CSCF is unreachable.

[0177] Specifically, the P-GW can detect that the P-CSCF is all unreachable by means such as sending a real-time ping message, an Internet Control Message Protocol (ICMP) packet, and the like. For example, the P-CSCF being unreachable can include the P-CSCF being unreachable due to a link failure or link congestion of the P-GW to the P-CSCF, or the P-CSCF being unreachable due to a failure of a P-CSCF network element, and the like.

[0178] 507: The P-GW sends a session establishment response message to the S-GW, indicating that the P-CSCF is unreachable.

[0179] The P-GW sends a session establishment response (Create Session Response) message to the S-GW, carrying a specific error code, such as a first error code, to indicate that the P-CSCF is unreachable.

[0180] Optionally, the session establishment response message can carry a first time length or a timer (Timer), such as a first timer, to indicate a retry period for the UE to re-access the IMS network, indicating that the UE needs to periodically attempt to access the IMS network according to the time length indicated by the first time length or the Timer until access is successful. The time length of the first timer can be the first time length.

[0181] 508: The S-GW sends a session establishment response message to the MME, indicating that the P-CSCF is unreachable.

[0182] The S-GW can forward the session establishment response message received from the P-GW to the MME, carrying the error code and optionally carrying the first time length or the first timer, and the like.

[0183] 509: The MME sends a PDN connection reject message to the terminal.

[0184] The PDN connection reject message corresponds to the first message in the embodiment of the preceding FIG. 4, and the PDN connection reject message can carry the error code allocated by the P-GW, and optionally carries the first time length or the first timer.

[0185] In an embodiment, if the session establishment response message received by the MME does not carry the indication of the timer information or the first time length, the MME can carry the indication of the timer information or the first time length in the PDN connection reject message sent to the terminal according to the preconfigured strategy.

[0186] 510: After the first time length expires or times out, the UE sends a PDN connection request message to the MME to request access to the IMS network.

[0187] The PDN connection request message sent by the UE to the MME after the first time length expires or times out corresponds to the second message in the embodiment of the preceding FIG. 4.

[0188] The PDN connection request message carries the APN as the IMS APN, indicating that the UE requests to access the IMS domain, and the P-CSCF address request parameter in the PCO information element, indicating that the UE requests the P-CSCF address.

[0189] In an embodiment, after receiving the message that the P-CSCF is unreachable, the UE can determine different processing based on different attachment modes of the UE. The attachment technology of the UE can include Packet Switched (PS) technology and Circuit Switched (CS) technology, and can specifically include PS mode 1, PS mode 2, CS / PS mode 1, and CS / PS mode 2.

[0190] The PS mode 1 means that the UE only registers the EPS service, and the use of the UE is set to "voice centric".

[0191] The PS mode 2 means that the UE only registers the EPS service, and the use of the UE is set to "data centric".

[0192] The CS / PS mode 1 means that the UE registers both the EPS and non-EPS services, and the use of the UE is set to "voice centric".

[0193] The CS / PS mode 2 means that the UE registers both the EPS and non-EPS services, and the use of the UE is set to "data centric".

[0194] Optionally, after receiving the message that the P-CSCF is unreachable, the UE can determine different processing based on the different attachment modes of the UE, as follows.

[0195] For the UE in the PS mode 1 and the PS mode 2, after determining that the P-CSCF is unreachable, the UE does not attempt CS fallback, but directly waits until the timer expires to reattempt access to the IMS network.

[0196] For the UE in the CS / PS mode 1 and the CS / PS mode 2, after receiving the P-CSCF unreachable error code, the UE first attempts to access the CS network, and if it is determined that there is no available CS network, the UE can periodically reattempt access to the IMS network according to a first time length or a first timer until successfully accessing the IMS network.

[0197] Embodiment two: applied to a 5G network, combined with FIG. 1, taking the network device AMF as an example.

[0198] As shown in FIG. 6, the communication method includes the following steps.

[0199] 601: The UE is powered on and establishes a default PDU session with the 5G core network.

[0200] 602: The UE sends a PDU session establishment request message to the AMF to request access to the IMS network.

[0201] The PDU session establishment request message can carry an ePCO information element to indicate a request for a P-CSCF address.

[0202] 603: The AMF selects an SMF.

[0203] 604: The AMF sends a PDU session context creation request message to the SMF.

[0204] Specifically, the AMF selects a suitable SMF and sends a PDU session context creation request (such as a PDU Session Create SMContext Request) message to the SMF to request creation of a PDU session de context.

[0205] Optionally, after receiving the PDU session context creation request, the SMF can obtain subscription data from the UDM and return a response indicating that the context corresponding to the PDU session has been established.

[0206] 605: The SMF selects a P-CSCF and determines that the P-CSCF is unreachable.

[0207] After receiving the PDU session context creation request, the SMF can obtain the address of the available P-CSCF from the NRF, and determine that the P-CSCF is unreachable.

[0208] Specifically, the process in which the SMF determines that the P-CSCF is unreachable can include the following manners:

[0209] (1) The P-CSCF periodically registers with the NRF, and the NRF can determine whether there is an available P-CSCF, so that the SMF can request the NRF to determine that the P-CSCF is unreachable.

[0210] (2) After the SMF obtains the list of accessible P-CSCF addresses from the NRF, the SMF can perform local storage and IP reachability detection on the P-CSCF, so as to determine that the P-CSCF is unreachable.

[0211] (3) The SMF can also receive a notification message from other network elements to determine, such as the UPF. When the UPF detects that the P-CSCF is unreachable, the UPF can notify the SMF of the P-CSCF being unreachable through the N4 interface message. Alternatively, when the AMF detects that the P-CSCF is unreachable, the AMF can notify the SMF of the P-CSCF being unreachable.

[0212] 606: The SMF sends a PDU session context creation response message to the AMF, indicating that the P-CSCF is unreachable.

[0213] The PDU session context creation response message is used to indicate that the P-CSCF is unreachable, and can correspond to the third message described in the foregoing embodiments, and is used to indicate the P-CSCF being unreachable to the mobility management device.

[0214] For example, the PDU session context creation response message can carry a specific error code, such as a first error code, to indicate that the P-CSCF is unreachable.

[0215] Optionally, the PDU session context creation response message can also carry a first time length or a timer, such as a first timer, to indicate a retry period for the UE to access the IMS network, that is, the UE needs to periodically attempt to access the IMS network according to the time length indicated by the first time length or the timer until the access is successful. The time length of the first timer can be the first time length.

[0216] 607: The AMF sends a PDU session establishment rejection message to the UE, indicating that the P-CSCF is unreachable.

[0217] Specifically, the PDU session establishment rejection message can carry the error code described above, and optionally carry the first time length or the first timer and the like.

[0218] 608: After the first time period expires or times out, the UE sends a PDU session establishment request message to the AMF, requesting to access the IMS network.

[0219] The PDU session establishment request message sent by the UE to the AMF after the first time period expires or times out corresponds to the second message in the embodiment of FIG. 4.

[0220] The P-CSCF address request parameter is included in the ePCO information element in the PDU session establishment request message, indicating that the UE requests the P-CSCF address.

[0221] The various embodiments mentioned in the foregoing of the present application can be combined without contradiction in the scheme, without limitation.

[0222] The above mainly introduces the scheme provided by the present application from the perspective of interaction between various network nodes. Correspondingly, the present application also provides a communication apparatus, which can be each communication apparatus or node in the above method embodiments, or a component such as a chip that can be used for the above communication apparatus or node.

[0223] It can be understood that the communication apparatus described above contains the corresponding hardware structure and / or software module for implementing each function. Those skilled in the art should easily realize that, in combination with the algorithm operation of each example described in the embodiments disclosed in the present application, the present application can be realized in the form of hardware or a combination of hardware and computer software. Whether a certain function is driven by hardware or computer software, it depends on the specific application and design constraints of the technical scheme. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0224] It should be understood that the above only describes the interaction between each network element node by way of example. In fact, the processing performed by the above communication apparatus or node is also not limited to being performed only by a single network element.

[0225] The present application can divide the functional modules of the communication apparatus according to the above method examples, for example, each functional module can be divided according to each function, or two or more functions can be integrated in one processing module. The above integrated module can be realized in the form of hardware or software functional module. It can be understood that the division of modules in the present application is illustrative, and is only a logical functional division. Actual implementation can have another division manner.

[0226] For example, in the case of dividing the functional modules in an integrated manner, FIG. 7 shows a structural schematic diagram of a communication apparatus 700. The communication apparatus 700 comprises an interface module 701.

[0227] In some embodiments, the communication apparatus 700 can further comprise a storage module (not shown in FIG. 7) for storing program instructions and data.

[0228] Exemplarily, the communication apparatus 700 can be used to implement the functions of the communication apparatus in the above-mentioned embodiment of FIG. 3. The communication apparatus 700 can be the terminal in each of the above-mentioned embodiments of FIG. 4-FIG. 6.

[0229] The interface module 701 can be configured to receive a first message, the first message being used to indicate that a proxy session control function is unreachable, and the first message indicating a first time length.

[0230] When the first time length expires or times out, the interface module 701 can be configured to send a second message, the second message being used to request access to the proxy session control function.

[0231] In an implementation, the first message comprises a first error code, and the first error code is used to indicate that the proxy session control function is unreachable.

[0232] In an implementation, the interface module 701 can be further configured to, when it is detected that there is no circuit switched (CS) network that can be accessed, send the second message to a network device after the first time length expires or times out.

[0233] In an implementation, the first message is a packet data network (PDN) connection reject message, and the second message is a PDN connection request message.

[0234] In an implementation, the first message is a session establishment reject message, and the second message is a session establishment request message.

[0235] In an implementation, the second message comprises first information, and the first information is used to indicate that an address of the proxy session control function is acquired.

[0236] In addition, the communication apparatus 700 can be used to implement the functions of the network device in the above-mentioned embodiments. FIG. 7 shows a structural schematic diagram of a communication apparatus 700. The communication apparatus 700 comprises an interface module 701 and a processing module 702. Exemplarily, the communication apparatus 700 is, for example, the network device in the above-mentioned embodiment of FIG. 4, or the MME in the above-mentioned embodiment of FIG. 5, or the AMF in the above-mentioned embodiment of FIG. 6.

[0237] The processing module 702 can be configured to determine that a proxy session control function is unreachable.

[0238] The interface module 701 can be configured to send, to the terminal, a first message, 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.

[0239] In an embodiment, the first message comprises a first error code, the first error code being used to indicate that the proxy session control function is unreachable.

[0240] In an embodiment, the interface module 701 can be further configured to receive a third message, the third message being used to indicate that the proxy session control function is unreachable. The processing module 702 can be configured to determine, according to the third message, that the proxy session control function is unreachable.

[0241] In an embodiment, the third message comprises the first time length.

[0242] In an embodiment, the communication apparatus 700 can be an access and mobility management function (AMF), or a mobility management entity (MME).

[0243] In an embodiment, the interface module 701 can be further configured to receive, from the terminal, a second message, the second message being used to request to access the proxy session control function.

[0244] In an embodiment, the first message is a session establishment reject message, and the second message is a session establishment request message.

[0245] In an embodiment, the first message is a packet data network connection reject message, and the second message is a packet data network connection request message.

[0246] In an embodiment, the second message comprises first information, the first information being used to indicate to obtain an address of the proxy session control function.

[0247] In addition, the communication apparatus 700 can be configured to implement the functions of the network device in the above embodiments. FIG. 7 shows a structural schematic diagram of a communication apparatus 700, which comprises an interface module 701 and a processing module 702. For example, the communication apparatus 700 can be a session management function in the above embodiments, for example, the P-GW in the embodiment of FIG. 5, or the SMF in the embodiment of FIG. 6.

[0248] The processing module 702 can be configured to determine that the proxy session control function is unreachable.

[0249] The interface module 701 can be configured to send, to the mobility management device, a third message, the third message being used to indicate that the proxy session control function is unreachable.

[0250] In an embodiment, the third message comprises a first error code, and the first error code is used to indicate that the proxy session control function is unreachable.

[0251] In an embodiment, the third message comprises a first time length, and the first time length is used to indicate a waiting time length of the terminal for requesting to access the proxy session control function.

[0252] In an embodiment, the mobility management device can be configured to receive the third message, determine that the proxy session control function is unreachable according to the third message, and send a first message to the terminal, wherein the first message is used to indicate that the proxy session control function is unreachable, and the first message indicates a first time length, and the first time length is used to indicate a waiting time length of the terminal for requesting to access the proxy session control function.

[0253] In an embodiment, the session management device is a packet data network (PDN) gateway, and the mobility management device is a mobility management entity (MME).

[0254] In an embodiment, the session management device is a session management function (SMF), and the mobility management device is an access and mobility management function (AMF).

[0255] In summary, when the communication apparatus 800 is configured to implement the functions performed by the communication apparatus or node in the above embodiments, the other functions that can be implemented by the communication apparatus 800 can refer to the descriptions of the above embodiments.

[0256] In a simple embodiment, the communication apparatus 700 can be in the form shown in FIG. 3, which can be conceived by those skilled in the art. For example, the processor 301 in FIG. 3 can execute the above method embodiments by invoking the computer-executable instructions stored in the memory 303.

[0257] For example, the functions / implementation processes of the processing module 702 in FIG. 7 can be implemented by the processor 301 in FIG. 3.

[0258] For example, the functions / implementation processes of the interface module 701 in FIG. 7 can be implemented by the communication interface 304 in FIG. 3.

[0259] It can be understood that one or more of the above modules or units can be implemented in software, hardware or a combination of both. When any of the above modules or units is implemented in software, the software exists in the form of computer program instructions and is stored in the memory, and the processor can be used to execute the program instructions and implement the above method flow. The processor can be built in the SoC (System on Chip) or ASIC, or be a separate semiconductor chip. The processor further includes the core for executing software instructions to perform operations or processing, and can further include necessary hardware accelerators, such as field programmable gate array (FPGA), programmable logic device (PLD), or logic circuit for implementing special logic operations.

[0260] When any of the above modules or units is implemented in hardware, the hardware can be any one or any combination of CPU, microprocessor, digital signal processing (DSP) chip, microcontroller unit (MCU), artificial intelligence processor, ASIC, SoC, FPGA, PLD, special purpose digital circuit, hardware accelerator or non-integrated discrete device, which can run necessary software or be independent of software to execute the above method flow.

[0261] In a possible implementation, the present application also provides a chip system, including at least one processor and an interface, the at least one processor is coupled with the memory through the interface, when the at least one processor executes the computer program or instructions in the memory, the method in any of the above method embodiments is executed. In a possible implementation, the chip system further includes the memory. Optionally, the chip system can be composed of a chip, or can include the chip and other discrete devices, and the present application does not make specific limitation hereon.

[0262] Optionally, the present application also provides a computer readable storage medium. All or part of the processes in the above method embodiments can be instructed by a computer program to relevant hardware to complete, the program can be stored in the above computer readable storage medium, and the program can include the processes of the above method embodiments when executed. The computer readable storage medium can be an internal storage unit of the communication device in any of the above embodiments, such as a hard disk or a memory of the communication device. The above computer readable storage medium can also be an external storage device of the above communication device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the above communication device. Further, the above computer readable storage medium can include both the internal storage unit and the external storage device of the above communication device. The above computer readable storage medium is used to store the above computer program and other programs and data required by the above communication device. The above computer readable storage medium can also be used to temporarily store data that has been output or will be output.

[0263] In a possible implementation, the present application also provides a computer program product. All or part of the processes in the above method embodiments can be instructed by a computer program to relevant hardware to complete, the program can be stored in the above computer program product, and the program can include the processes of the above method embodiments when executed.

[0264] In a possible implementation, the present application also provides a computer instruction. All or part of the processes in the above method embodiments can be instructed by a computer instruction to relevant hardware (such as a computer, a processor, a network device, or a terminal device, etc.) to complete. The program can be stored in the above computer readable storage medium or the above computer program product.

[0265] In a possible implementation, the present application also provides a communication system, including the terminal and the network device in the above embodiments. Exemplarily, the network device can be a mobility management device.

[0266] In a possible implementation, the communication system can also include the session management device in the above embodiments.

[0267] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional modules is taken as an example for illustration, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.

[0268] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. For example, the embodiments of the apparatus described above are merely schematic, and the division of the modules or units is merely logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another device, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, or the among different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0269] The units described as separated components can or can not be physically separated, and the components displayed as units can be located in one place or can be distributed to multiple places. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments.

[0270] In addition, each functional unit in the embodiments of the present application can be integrated in a processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in one unit. The integrated unit can be implemented in the form of hardware, or in the form of a software functional unit.

[0271] The above describes only the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection 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 of claim 16 or 17, wherein, 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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