A communication method and apparatus

Abstract

This application provides a communication method and apparatus for reducing the transmission latency of IMS service data. The method includes: a first core network element receiving first information from a second core network element, the first information being IMS-related data; the first core network element sending the first information and second information to an access network element, the second information indicating that the first information is transmitted via an SRB corresponding to an RLC mode that does not support retransmission.

Description

Technical Field

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

[0002] Internet Protocol Multimedia Subsystem (IMS) related data (such as IMS service data) is generally transmitted via a data radio bearer (DRB). Therefore, the terminal needs to support the establishment of a DRB and have a usable DRB. However, for terminals that do not support the establishment of a DRB or do not have a usable DRB, such as narrowband (NB) Internet of Things (IoT) devices, IMS service data needs to be transmitted via a signaling radio bearer (SRB).

[0003] However, reducing the transmission latency of IMS service data when transmitting IMS service data via SRB is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application provides a communication method for reducing the transmission latency of IMS service data.

[0005] Firstly, a communication method is provided, which can be applied to a first core network element. For example, the first core network element can be a first network device with first core network element functions, or it can be a device within the first network device (e.g., a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a system-on-a-chip (SoC) chip containing a modem core, or a system-in-package (SIP) chip), chip system, or processor), or it can be a logical node, logical module, or software capable of implementing all or part of the first network device. The method includes: the first core network element receiving first information from a second core network element, the first information being IMS-related data; the first core network element sending the first information and second information to an access network element, the second information being used to instruct the transmission of the first information through a signaling radio bearer (SRB) corresponding to a radio link control (RLC) mode that does not support retransmission mechanisms.

[0006] In this embodiment of the application, when transmitting IMS-related data via SRB, the first core network element can instruct the access network element to transmit IMS-related data via the SRB corresponding to the RLC mode that does not support retransmission mechanism. This can reduce the latency caused by the retransmission mechanism, thereby helping to reduce the transmission latency of IMS-related data.

[0007] In one possible implementation, the second information includes indication information, which indicates that the first information is IMS-related data.

[0008] In the above technical solution, the first information is IMS-related data, indicating that the first information needs to be transmitted through the SRB corresponding to the RLC mode, which does not support retransmission mechanisms. The indication method is relatively flexible. In addition, using indication information to realize the function of the second information is only one example. The function of the second information can also be realized in other ways. For example, the second information can be a special message format or information element, which can indicate the information type of the first information.

[0009] In one possible implementation, the method further includes: a first core network element determining that the first information is IMS-related data based on the connection identifier and / or the address information of the terminal device corresponding to the first information.

[0010] In the above technical solution, the first information is determined to be IMS-related data by the first core network element. This does not require any modification to the communication process between other core network elements on the link that transmits IMS-related data, making the implementation relatively simple.

[0011] In one possible implementation, the connection identifier includes: a packet data network (PDN) connection identifier, and / or, a tunnel identifier.

[0012] In the above technical solution, determining the information type transmitted according to the connection identifier conforms to the provisions of existing protocols. Furthermore, the identifier types included in the connection identifier are merely examples; for instance, the connection identifier could also be a protocol data unit (PDU) session identifier, and this application embodiment does not limit this.

[0013] In one possible implementation, the method further includes: a first core network element receiving the second information from a second core network element.

[0014] In the above technical solution, the second core network element is, for example, a serving gateway (SGW). The first information is determined to be IMS-related data through the second core network element, making the way IMS-related data is transmitted in this embodiment closer to the way IMS-related data is transmitted in the user plane.

[0015] In one possible implementation, the method further includes: a first core network element sending third information to a second core network element, the third information being used to instruct the second core network element to send the second information in the event that the first information has been sent.

[0016] In one possible implementation, the first core network element sends the first information to the access network element, including: the first core network element sending a first non-access stratum (NAS) message to the access network element, the first NAS message including the first information. The sending of IMS-related data transmitted via the control plane through the NAS message conforms to existing protocol specifications.

[0017] In one possible implementation, the first NAS message further includes the second information. The use of the second information carried within the first NAS message is merely an example; the second information can also be a specific NAS message format or element. This application does not limit the implementation method of the second information.

[0018] In one possible implementation, the method further includes: a first core network element sending fourth information to the access network element; wherein the fourth information is used by the access network element to establish a first SRB and transmit IMS-related data through the first SRB, wherein the RLC mode corresponding to the first SRB is a mode that does not support retransmission; or, the fourth information is used by the access network element to transmit IMS-related data through SRB0; or, the fourth information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission; or, the fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, wherein the RLC mode of the first RLC entity is a mode that does not support retransmission; or, the fourth information is used by the access network element to configure or enable a first function, wherein the first function is used to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission when transmitting IMS-related data through the second SRB; wherein the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3, or SRB4.

[0019] In the above technical solution, an SRB is established for transmitting IMS-related data. This approach ensures low latency for IMS-related data transmission without requiring modifications to existing SRBs, making implementation simple. Furthermore, by transmitting IMS-related data through SRB0, modifying the RLC mode of the existing SRB to an RLC mode that does not support retransmission, or configuring an RLC entity that does not support retransmission for the existing SRB, the probability of IMS-related data retransmission can be reduced, thereby helping to lower the transmission latency of IMS-related data.

[0020] In one possible implementation, the method further includes: a first core network element receiving fifth information from a terminal device, the fifth information indicating that the terminal device has the capability to transmit IMS-related data through the control plane, the terminal device being the target device corresponding to the first information. Optionally, the first core network element may also receive sixth information from a third core network element, the sixth information indicating that the terminal device is authorized to transmit IMS-related data through the control plane, the terminal device being the target device corresponding to the first information.

[0021] In one possible implementation, the terminal device accesses the network via Internet of Things (IoT) access technology. Optionally, the terminal device does not support establishing a data radio bearer (DRB); or, the terminal device has zero available DRBs.

[0022] In the above technical solution, the terminal device accesses the network through Internet of Things (e.g., narrowband Internet of Things) access technology, indicating that the terminal device may not have any available DRBs (i.e., the number of available DRBs is 0), or the terminal device does not support the establishment of DRBs. The terminal device cannot transmit IMS-related data through the user plane and needs to transmit IMS-related data through the control plane, that is, transmit IMS-related data through SRBs.

[0023] Secondly, a communication method is provided, which can be applied to an access network element. For example, the access network element can be an access network device with access network element functions, or it can be a device within the access network device (e.g., a module, communication module, circuit or chip responsible for communication functions (such as a modem chip, or a SoC chip or SIP chip containing a modem core), chip system, or processor), or it can be a logical node, logical module, or software capable of implementing all or part of the access network device. The method includes: the access network element receiving first information and second information from a first core network element, wherein the first information is IMS-related data, and the second information is used to indicate that the first information is transmitted through an SRB corresponding to an RLC mode that does not support retransmission; the access network element determines, based on the second information, to send the first information to a terminal device through a first SRB, wherein the RLC mode corresponding to the first SRB is a mode that does not support retransmission.

[0024] In one possible implementation, the second information includes indication information, which indicates that the first information is IMS-related data; the access network element determines to send the first information to the terminal device through the first SRB according to the second information, including: the access network element determines to send the first information to the terminal device through the first SRB corresponding to the RLC mode that does not support retransmission mechanism according to the indication information.

[0025] In one possible implementation, the access network element sends the first information to the terminal device through the first SRB, including: the access network element sends a first NAS message to the terminal device through the first SRB, the first NAS message including the first information.

[0026] In one possible implementation, the method further includes: an access network element receiving fourth information from the terminal device or the first core network element; wherein the fourth information is used by the access network element to establish a first SRB and transmit IMS-related data through the first SRB, wherein the RLC mode corresponding to the first SRB is a mode that does not support retransmission; or, the fourth information is used by the access network element to transmit IMS-related data through SRB0; or, the fourth information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission; or, the fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, wherein the RLC mode of the first RLC entity is a mode that does not support retransmission; or, the fourth information is used by the access network element to configure or enable a first function, wherein the first function is used to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission when transmitting IMS-related data through the second SRB; wherein the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3, or SRB4.

[0027] In one possible implementation, the fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB. The access network element sends the first information to the terminal device through the first SRB, including: the access network element sending the first information to the terminal device through the first RLC entity corresponding to the second SRB.

[0028] In one possible implementation, the terminal device accesses the network via Internet of Things (IoT) access technology.

[0029] In one possible implementation, the terminal device does not support establishing DRBs; or, the number of DRBs available to the terminal device is 0.

[0030] Thirdly, a communication method is provided, which can be applied to a terminal-side device. This terminal-side device is also referred to as a terminal device. The terminal device is, for example, a terminal equipment, or other equipment including terminal equipment functions, or a circuit, or a system-on-a-chip (or a chip, such as a modem chip, also known as a baseband chip, or a SoC chip or SIP chip containing a modem core) or other functional module, which can realize the functions of the terminal equipment, and is, for example, disposed in the terminal equipment. For ease of description, in the embodiments of this application, the communication method provided in the third aspect is applied to a terminal equipment as an example. The method includes: the terminal equipment sending seventh information to an access network element through a first SRB, the seventh information being IMS-related data, and the RLC mode corresponding to the first SRB being a mode that does not support retransmission mechanisms.

[0031] In one possible implementation, the terminal device sends a seventh message to the access network element, including: the terminal device sending a second non-access stratum (NAS) message to the access network element, wherein the second NAS message includes the seventh message.

[0032] In one possible implementation, the method further includes: the terminal device sending a fourth message to the access network element; wherein the fourth message is used by the access network element to establish a first SRB and transmit IMS-related data through the first SRB, wherein the RLC mode corresponding to the first SRB is a mode that does not support retransmission; or, the fourth message is used by the access network element to transmit IMS-related data through SRB0; or, the fourth message is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission; or, the fourth message is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, wherein the RLC mode of the first RLC entity is a mode that does not support retransmission; or, the fourth message is used by the access network element to configure or enable a first function, wherein the first function is used to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission when transmitting IMS-related data through the second SRB; wherein the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3, or SRB4.

[0033] In one possible implementation, the method further includes: the terminal device sending fifth information to a first core network element, the fifth information being used to indicate that the terminal device has the capability to transmit IMS-related data through the control plane.

[0034] In one possible implementation, the terminal device accesses the network via Internet of Things (IoT) access technology.

[0035] In one possible implementation, the terminal device does not support establishing a Data Radio Bearer (DRB); or, the number of DRBs available to the terminal device is 0.

[0036] Fourthly, a communication device is provided. The communication device can be a first core network element as described in any of the first to third aspects above. The communication device possesses the functions of the first core network element. For example, the communication device can implement the functions of the first core network element as described in any of the first to third aspects above. For example, the communication device includes modules, units, or means corresponding to the operations involved in the first core network element in any of the first to third aspects above. These modules, units, or means can be implemented through software, hardware, or a combination of software and hardware. In one optional implementation, the communication device includes a baseband device and a radio frequency device.

[0037] In another optional implementation, the communication device includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module). The transceiver unit is capable of both sending and receiving functions. When the transceiver unit performs the sending function, it can be called a sending unit (sometimes also called a sending module); when the transceiver unit performs the receiving function, it can be called a receiving unit (sometimes also called a receiving module). The sending unit and the receiving unit can be the same functional module, which is called the transceiver unit and can perform both sending and receiving functions; alternatively, the sending unit and the receiving unit can be different functional modules, and the transceiver unit is a collective term for these functional modules.

[0038] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive first information from a second core network element, the first information being IMS-related data; and the transceiver unit (or the sending unit) is configured to send first information and second information to an access network element, the second information being used to instruct the transmission of the first information via an SRB corresponding to an RLC mode that does not support retransmission mechanisms.

[0039] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the first core network element described in any one of the first to third aspects above.

[0040] Fifthly, a communication device is provided. The communication device can be a second core network element as described in the first or second aspect above. The communication device possesses the functions of the aforementioned second core network element. For example, the communication device has the function of implementing the second core network element as described in the first or second aspect. For example, the communication device includes modules, units, or means corresponding to the operations involved in the second core network element described in the first or second aspect. These modules, units, or means can be implemented through software, hardware, or a combination of software and hardware. In one optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the relevant description in the fourth aspect.

[0041] In one optional implementation, the transceiver unit (or the receiving unit) is configured to receive first information and second information from a first core network element, wherein the first information is IMS-related data, and the second information is configured to indicate that the first information is transmitted through an SRB corresponding to an RLC mode that does not support retransmission; and the transceiver unit (or the sending unit) is configured to determine, based on the second information, to send the first information to the terminal device through a first SRB, wherein the RLC mode corresponding to the first SRB is a mode that does not support retransmission.

[0042] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the second core network element described in the first or second aspect above.

[0043] Sixthly, a communication device is provided. The communication device can be a terminal device as described in any of the first to third aspects above. The communication device possesses the functions of the aforementioned terminal device. For example, the communication device has the functions of a terminal device as described in any of the first to third aspects above; for example, the communication device includes modules, units, or means corresponding to operations involving the terminal device as described in any of the first to third aspects above. These modules, units, or means can be implemented in software, hardware, or a combination of software and hardware. In one optional implementation, the communication device includes a baseband device and a radio frequency device. In another optional implementation, the communication device includes a processing unit (sometimes also called a processing module) and a transceiver unit (sometimes also called a transceiver module). For details on the implementation of the transceiver unit, please refer to the relevant description in the fourth aspect.

[0044] In one optional implementation, the transceiver unit (or the sending unit) is configured to send seventh information to the access network element via a first SRB, the seventh information being IMS-related data, and the RLC mode corresponding to the first SRB being a mode that does not support retransmission mechanism.

[0045] In an alternative embodiment, the communication device further includes a storage unit (sometimes also called a storage module), and the processing unit is configured to couple with the storage unit and execute programs or instructions in the storage unit to enable the communication device to perform the functions of the terminal device described in any one of the first to third aspects above.

[0046] A seventh aspect provides a communication device comprising a memory and one or more processors. The memory stores part or all of a computer program or instructions necessary for implementing the functions described in the first aspect. The one or more processors are executable to carry out the computer program or instructions, such that, when executed, the communication device implements the methods in any possible design or implementation of the first aspect.

[0047] In one possible design, the communication device may further include an interface circuit, through which the processor communicates with other devices or components.

[0048] In one possible design, the communication device may also include the memory.

[0049] The aforementioned communication device may be a network device, a communication module within a network device, or a chip within a network device responsible for communication functions, such as a modem chip (also known as a baseband chip), or a SoC or SIP chip containing a modem module. Optionally, the network device may implement any of the possible designs or implementations described in the first aspect.

[0050] Eighthly, a communication device is provided, the communication device including a memory and one or more processors. The memory is used to store part or all of a computer program or instructions necessary for implementing the functions involved in the first aspect above. The one or more processors are executable to carry out the computer program or instructions, such that when the computer program or instructions are executed, the communication device implements the methods in any possible design or implementation of the second aspect above.

[0051] In one possible design, the communication device may further include an interface circuit, through which the processor communicates with other devices or components.

[0052] In one possible design, the communication device may also include the memory.

[0053] The aforementioned communication device may be a network device, a communication module within a network device, or a chip within a network device responsible for communication functions, such as a modem chip (also known as a baseband chip), or a SoC or SIP chip containing a modem module. Optionally, the network device may implement any of the possible designs or implementations described in the second aspect.

[0054] A ninth aspect provides a communication device comprising a memory and one or more processors. The memory stores part or all of a computer program or instructions necessary for implementing the functions described in the third aspect above. The one or more processors are executable to carry out the computer program or instructions, such that, when executed, the communication device implements the methods in any possible design or implementation of the third aspect above.

[0055] In one possible design, the communication device may further include an interface circuit, through which the processor communicates with other devices or components.

[0056] In one possible design, the communication device may also include the memory.

[0057] The aforementioned communication device may be a terminal, a communication module within a terminal, or a chip within a terminal responsible for communication functions, such as a modem chip (also known as a baseband chip), or a SoC or SIP chip containing a modem module. Optionally, the terminal may implement any of the methods in the third aspect of the design or implementation.

[0058] A tenth aspect provides a communication system comprising a first core network element and a second core network element, wherein the first core network element is configured to perform the method described in any one of the first to third aspects; and the second core network element is configured to perform the method described in the first aspect. For example, the first core network element may be implemented using the communication apparatus described in the fourth or seventh aspect.

[0059] Optionally, the communication system may further include a third core network element, which is used to perform the method described in the first aspect above.

[0060] Eleventhly, a communication system is provided, comprising an access network element and a first core network element, wherein the first core network element is used to execute the method described in any one of the first to third aspects; and the access network element is used to execute the method described in any one of the first to third aspects. For example, the first core network element can be implemented using the communication device described in the fourth or seventh aspect; and the access network element can be implemented using the communication device described in the fifth or eighth aspect.

[0061] Optionally, the communication system may further include a terminal device for performing the method described in any one of the first to third aspects. For example, the terminal device may be implemented using the communication apparatus described in the sixth or ninth aspect.

[0062] In a twelfth aspect, a computer-readable storage medium is provided for storing a computer program or instructions that, when executed, cause the method performed by the first core network element, access network element, or terminal device in the above aspects to be implemented.

[0063] In a thirteenth aspect, a computer program product containing instructions is provided, which, when the computer program or instructions are run on a computer, causes the methods described in the above aspects to be implemented.

[0064] In a fourteenth aspect, a chip system is provided, including a processor and an interface, the processor being configured to call and execute instructions from the interface to enable the chip system to implement the methods of the above aspects.

[0065] The technical effects that can be achieved by any of the second to fourteenth aspects mentioned above can be described with reference to the technical effects that can be achieved by any possible implementation of the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the air interface protocol layer between a terminal device and an access network device.

[0067] Figure 2 An example of a PDN connection;

[0068] Figure 3A and Figure 3B These are schematic diagrams illustrating two network architectures applicable to embodiments of this application;

[0069] Figure 4 A flowchart of a communication method provided in this application;

[0070] Figure 5 A flowchart of another communication method provided in this application;

[0071] Figure 6 A flowchart of another communication method provided in this application;

[0072] Figure 7 A flowchart of another communication method provided in this application;

[0073] Figure 8 A schematic diagram of an apparatus provided in an embodiment of this application;

[0074] Figure 9 This is a schematic diagram of another device provided in an embodiment of this application. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0076] In this application embodiment, the number of nouns, unless otherwise specified, refers to "singular nouns or plural nouns," that is, "one or more." "At least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. For example, A / B means: A or B. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0077] The ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, priority, or importance of the multiple objects. Furthermore, the numbering of steps in the various embodiments described in this application is only to distinguish different steps and is not used to limit the order in which the steps are performed.

[0078] The following explanations of some terms or concepts used in the embodiments of this application are provided to facilitate understanding by those skilled in the art (see 3rd generation partnership project (3GPP) protocols TS36.322, 36.331, 38.322, 38.331, 23.401 for details).

[0079] (1)SRB

[0080] SRBs are used to transmit control plane signaling, that is, SRBs are used to transmit control signaling between terminal equipment and access network equipment or core network elements, such as radio resource control (RRC) messages, NAS messages, etc.

[0081] For example, SRB0: used to transmit messages before the initial RRC connection is established.

[0082] SRB1: Used to transmit the main signaling after the RRC connection is established, that is, to transmit RRC messages and some NAS messages (such as NAS messages before the NAS security connection is established).

[0083] SRB2: Used to transmit NAS messages, with a lower priority than SRB1.

[0084] SRB1bis: An SRB specific to NB-IoT devices, used to transmit NAS messages, and its function is basically the same as SRB2. The difference between SRB1bis and SRB2 is that when using SRB1bis to transmit NAS messages, there is no PDCP layer in the air interface protocol layer, which reduces the length of the packet header.

[0085] (2) DRB

[0086] DRBs are used to transmit user plane data, meaning they transmit service data (such as video, voice, and web pages) between terminal devices and service servers. Multiple DRBs can be established between terminal devices and access network equipment. In fourth-generation (4G) mobile communication systems, each DRB corresponds to a different user plane bearer (also known as a session or PDN connection). Different DRBs can provide the same or different Quality of Service (QoS) for data transmission. For example, DRB 1 is the default bearer and does not guarantee QoS, while DRB 2 is a dedicated bearer that guarantees a certain maximum latency.

[0087] (3) RLC

[0088] Please refer to Figure 1 This is a schematic diagram of the air interface protocol layer between a terminal device and an access network device. For example... Figure 1 As shown, the air interface protocol layer between the terminal device and the access network device includes the Medium Access Control (MAC) layer, the RLC layer, the Packet Data Convergence Protocol (PDCP) layer, and the Service Data Adaptation Protocol (SDAP) layer. The dashed arrows indicate the data processing flow.

[0089] The RLC layer provides functions such as segmentation, reassembly, and retransmission to ensure data transmission integrity. The RLC layer supports the following three operating modes:

[0090] Transparent mode (TM): When the RLC layer operates in TM mode, MAC and PDCP can transmit data to each other, essentially eliminating the need for an RLC layer. TM mode is primarily used in scenarios where data segmentation or reliable transmission is not required, such as system broadcasting and paging.

[0091] Unacknowledged mode (UM): When the RLC layer operates in UM mode, it has packet segmentation and reassembly mechanisms, but no retransmission mechanism. The presence of packet segmentation and reassembly mechanisms can be understood as the RLC layer possessing packet segmentation and reassembly capabilities, while the lack of a retransmission mechanism can be understood as the absence of retransmission functionality. UM mode is primarily used in latency-sensitive service scenarios that tolerate a small amount of packet loss, such as user plane data transmission scenarios (IMS services, data traffic services, etc.).

[0092] Acknowledged mode (AM): When the RLC layer operates in AM mode, it has packet fragmentation, reassembly, and retransmission mechanisms. This means the RLC layer possesses packet fragmentation, reassembly, and retransmission capabilities. AM mode is primarily used in high-reliability service scenarios, such as control plane signaling transmission.

[0093] 3GPP defines the relationship between the operating modes of the RLC layer and the radio bearers. For example, the operating mode of the RLC layer corresponding to SRB0 is defined as TM mode, the operating mode of the RLC layer corresponding to SRB1, SRB2, and SRB1bis is defined as AM mode, and the operating mode of the RLC layer corresponding to DRB is defined as UM mode.

[0094] (4) NB-IoT

[0095] NB-IoT is a radio access technology (RAT) that supports low-power devices connecting to wide area networks. It boasts advantages such as wide coverage, large capacity, low power consumption, low cost, and superior architecture. NB-IoT can be widely applied in various vertical industries, such as remote meter reading and smart streetlights.

[0096] Terminals accessing the NB-IoT network (referred to as NB-IoT devices) generally have limited capabilities, supporting only 0-2 DRBs. This means an NB-IoT device may have no available DRBs, or at most two available DRBs. For NB-IoT devices without available DRBs, such as those that do not support DRB establishment, a control plane PDN connection can be established to transmit service data, i.e., service data is transmitted via SRBs.

[0097] (5) PDN connection

[0098] A PDN connection is a connection between a terminal device and an external network (such as a PDN). A PDN connection can include a user plane PDN connection and a control plane PDN connection. The user plane PDN connection is used for data transmission between the user equipment (UE) and the PDN, while the control plane PDN connection is used for signaling transmission between the UE and the PDN. For example, please refer to [reference needed]. Figure 2 This is an example of a PDN connection. Figure 2This includes: UE, radio access network (RAN) network elements, mobility management entity (MME) network elements, serving gateway control plane (SGW-C) network elements, packet data network gateway control plane (PGW-C) network elements, serving gateway user plane (SGW-U) network elements, packet data network gateway user plane (PGW-U) network elements, and PDN. The connection between SGW-U and PGW-U is a user plane PDN connection, and the connection between MME, SGW-C, and PGW-C is a control plane PDN connection.

[0099] The control plane PDN connection can also be used to realize data transmission between the UE and the PDN. For example, for NB-IoT devices that do not support DRB establishment, their service data needs to be transmitted through SRB, that is, the service data of the NB-IoT device needs to be transmitted through the control plane PDN connection. For example, during uplink data transmission, the NB-IoT device can carry data packets in NAS messages (e.g., NAS PDUs) and send the NAS message to the RAN through SRB1bis. The RAN then forwards the NAS message to the MME through the S1 interface. The MME sends the data packet to the SGW (e.g., the control plane tunnel) through the tunnel between the UE and the SGW (i.e., the control plane tunnel). Figure 2 The SGW-C shown is an example of an SGW (e.g., SGW-C). Figure 2 The SGW-U shown here communicates with a packet data network gateway (PGW) (e.g., Figure 2 The tunnel between the PGW-U (as shown) sends the data packet to the PGW-U, and the PGW-U sends the data packet to the server (e.g., the IMS in the core network).

[0100] During downlink data transmission, the IMS sends the data packet to the PGW-U, which then sends the data packet to the SGW-U via a tunnel between the PGW-U and the SGW-C. The SGW-C then sends the data packet to the MME via a control plane tunnel between the SGW-C and the MME. The MME carries the data packet in a NAS PDU and sends the NAS message to the RAN via the S1 interface. The RAN then sends the NAS message to the NB-IoT device via the SRB1bis.

[0101] (6) VoIP

[0102] In Long Term Evolution (LTE) and New Radio (NR) systems, VoIP is implemented in the packet-switched (PS) domain.

[0103] Terminal devices implement voice calls in the PS domain based on IMS. In LTE systems, this voice call is also called Voice over LTE (VoLTE). The terminal device accesses the evolved Node B (eNB) of the evolved universal terrestrial radio access network (UTRAN) via an air interface link, and then connects to the IMS in the core network. Similarly, in NR systems, VoIP is called Voice over NR (VoNR), and the terminal device accesses the NR base station (gNB) via an air interface link, and then connects to the IMS in the core network.

[0104] (7) Terminal equipment

[0105] A terminal device is a device with wireless transceiver capabilities. It can be a fixed device, a mobile device, a handheld device (such as a mobile phone), a wearable device, an in-vehicle device, or a wireless device (such as a communication module, modem, or chip system) built into the above devices. The terminal devices are used to connect people, objects, and machines, and can be widely used in various scenarios, including but not limited to the following: sensing scenarios, cellular communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, machine-to-machine / machine-type (M2M / MTC) communication, internet of things (IoT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, remote medical care, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart city, drones, robots, indoor commercial scenarios (such as mobile phone screen mirroring, file sharing, and mobile phone to VR glasses video transmission), satellite communication, and other scenarios. When the terminal device is applied to V2X, it can also be called a V2X device, such as a smart car, digital car, unmanned car, driverless car, pilotless car, or automobile, self-driving car, or autonomous car, pure electric vehicle (EV), hybrid electric vehicle (HEV), range-extended electric vehicle (REEV), plug-in hybrid electric vehicle (PHEV), new energy vehicle, or roadside unit (RSU). The terminal device can also be a device in D2D communication, such as an electricity meter or water meter. The terminal device can also be a terminal device in an IoT system. IoT is an important component of future information technology development, and its main technical characteristic is connecting objects to networks through communication technology, thereby realizing an intelligent network of human-machine interconnection and machine-to-machine interconnection.In this embodiment of the application, the terminal device is taken as an example of a terminal device in an IoT system.

[0106] The various terminal devices described above, if located in a vehicle (e.g., placed inside or installed inside a vehicle), can all be considered in-vehicle terminal devices, also known as on-board units (OBUs). The terminal device of this application can also be an in-vehicle module, in-vehicle component, in-vehicle chip, or in-vehicle unit built into a vehicle as one or more components or units. The vehicle can implement the methods of this application through the built-in in-vehicle module, in-vehicle component, in-vehicle chip, or in-vehicle unit.

[0107] The terminal equipment may sometimes be referred to as user equipment (UE), terminal, access station, UE station, remote station, wireless communication equipment, or user device, etc.

[0108] In this application embodiment, the communication device used to implement the terminal device function can be the terminal device itself, or it can be a device capable of supporting the terminal device in implementing the function, such as a chip system. This device can be installed in the terminal device. In the technical solutions provided in this application embodiment, the terminal device is used as an example to describe the technical solutions provided in this application embodiment. Furthermore, for ease of description, the terminal device in this application embodiment is described using a UE as an example.

[0109] (8) Access network equipment

[0110] Access network equipment refers to radio access network (R)AN equipment / RAN nodes. R)AN and RAN are interchangeable; for ease of description, RAN will be used as an example below. RAN can be a 3GPP-related cellular system, such as Long Term Evolution (LTE), 5th Generation (5G) / New Radio (NR) mobile communication systems, or future-oriented evolution systems. RAN can also be an open RAN (O-RAN or ORAN), a cloud radio access network (CRAN), a virtualized RAN (vRAN), or a non-terrestrial network (NTN) (e.g., satellite communication systems). RAN can also be a communication system that integrates two or more of the above systems. RAN equipment can also be called RAN nodes, RAN entities, or access nodes. In future scenarios, RAN nodes may also have other evolved forms; for example, RAN nodes may not be distinguished from core network equipment and may be collectively referred to as network equipment.

[0111] In one possible scenario, a RAN node can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation nodeB (gNB), a satellite (or satellite base station), or a high-altitude platform station (HAPS), or base station equipment mounted on a satellite / HAPS, or a base station in a future mobile communication system. The satellite can include at least one of the following: a geostationary orbit (GEO) satellite or a non-geostationary orbit (NGEO) satellite. A non-geostationary orbit satellite can include at least one of the following: a medium Earth orbit (MEO) satellite or a low Earth orbit (LEO) satellite. There are no restrictions here. RAN nodes can also be macro base stations, micro base stations, indoor stations, relay nodes, donor / host nodes, or wireless controllers. RAN nodes can also be servers, wearable devices, vehicles, or in-vehicle equipment. For example, in vehicle-to-everything (V2X) technology, the RAN node can be a roadside unit (RSU). The AP (Access Point) can serve as the central hub of this communication system and can be a base station, router, gateway, repeater, communication server, switch, or bridge, etc., equipped with a Wi-Fi chip. RAN nodes can also be gateway stations (or ground stations, earth stations, signaling stations, gateways, or gateway stations).

[0112] In another possible scenario, the RAN node can be a module or unit that performs some of the functions of the base station; or multiple RAN nodes can cooperate to assist terminal equipment in achieving wireless access, with different RAN nodes performing some of the functions of the base station. For example, the RAN node can be a CU, DU, or RU. The function of the CU can be implemented by a single entity or by different entities. For example, the function of the CU can be further divided, that is, the control plane and the user plane can be separated and implemented by different entities, namely the control plane CU entity (i.e., CU-control plane (CP) entity) and the user plane CU entity (i.e., CU-user plane (UP) entity). The CU-CP entity and the CU-UP entity can be coupled with the DU to jointly complete the function of the RAN node. The CU and DU can be set up separately or included in the same network element, such as in the baseband unit (BBU). Any of the units among the CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented by software modules, hardware modules, or a combination of software modules and hardware modules.

[0113] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples.

[0114] The CU and DU can be configured according to the protocol layer functions of the wireless network they implement. For example, the CU can be configured to implement the functions of the PDCP layer and higher protocol layers (such as the RRC layer and / or SDAP layer). The CU connects to network nodes such as the core network through interfaces, which can be E2 interfaces. Optionally, the CU can have some core network functions. The CU (e.g., PDCP layer and higher) connects to the DU (e.g., RLC layer and lower) through interfaces. For example, the DU can be configured to implement the functions of protocol layers below the PDCP layer (e.g., RLC, MAC layer, and / or physical (PHY) layer). For specific descriptions of the above protocol layers, please refer to the relevant 3GPP technical specifications or the technical specifications of other applicable communication protocols.

[0115] The above division of CU and DU processing functions according to the protocol layer is merely an example; other division methods are also possible, and this application does not impose any restrictions.

[0116] For example, in one design, the CU or DU can be further divided into processing functions with protocol layers. In one design, some functions of the RLC layer and the protocol layer functions above the RLC layer are located in the CU, while the remaining functions of the RLC layer and the protocol layer functions below the RLC layer are located in the DU. In another possible design, the DU and RU cooperate to implement the PHY layer functions, or it can be described as moving some of the PHY layer functions of the DU to the RU. A DU can be connected to one or more RUs. The functions of the DU and RU can be configured in various ways depending on the design. For example, the DU is configured to implement baseband functions, and the RU is configured to implement mid-RF functions. As another example, the DU is configured to implement higher-level functions in the PHY layer, and the RU is configured to implement lower-level functions in the PHY layer, or to implement both lower-level and RF functions.

[0117] When the RAN is O-RAN, it can also have artificial intelligence (AI) capabilities. For example, O-RAN includes an intelligent controller. The intelligent controller can be a non-real-time RAN intelligent controller (RIC / non-RT RIC / NRTRIC) or a near-real-time RAN intelligent controller (RIC / nRT RIC / nRT RIC). A non-real-time RIC can be used to implement non-real-time intelligent management of RAN functions, enabling workflows including model training and updates, and guiding applications / functions in the nRT RIC based on policies. A near-real-time RIC can be used to implement near-real-time intelligent management of the RAN. Through data collection and related operations on the E2 interface, near-real-time control and optimization of O-RAN modules and resources are achieved.

[0118] The technical features involved in the embodiments of this application are described below.

[0119] In its Release 20 discussions, 3GPP mentioned that NB-IoT devices should support IMS services. Currently, IMS service data is transmitted by establishing dedicated user plane sessions, meaning it's transmitted via DRBs, and the RLC mode corresponding to a DRB does not support retransmission. However, NB-IoT devices can only establish 0-2 DRBs, meaning they may not have any available DRBs (only supporting 0 DRBs, or the DRB is occupied by other services). For NB-IoT devices without available DRBs, transmission via SRB1bis can be considered. SRB1bis corresponds to AM mode in RLC, which supports retransmission. However, if SRB1bis is used to transmit IMS service data, the AM mode's retransmission mechanism may increase communication latency.

[0120] Therefore, in this embodiment of the application, when transmitting IMS-related data via SRB, it can be instructed to transmit IMS-related data via SRB corresponding to RLC mode that does not support retransmission mechanism. This can reduce the latency caused by retransmission mechanism, thereby helping to reduce the transmission latency of IMS-related data.

[0121] The technical solutions provided in this application can be applied to 4G systems, such as LTE systems, or 5G systems, such as NR systems, or next-generation mobile communication systems or other similar communication systems, or satellite mobile communication technology systems, such as communication systems where the UE accesses the network via a GEO satellite. Specific applications are not limited. The technical solutions provided in this application can be applied to NTN (Network-to-Network) systems, or non-NTN systems, such as terrestrial cellular networks. For example, this application can be applied to scenarios where multiple network devices or multiple cells need to perform joint transmission. Furthermore, the technical solutions provided in this application can also be applied to D2D scenarios, such as NR-D2D scenarios, or V2X scenarios, such as NR-V2X scenarios. For example, this application can be used in fields such as factory manufacturing, smart homes, intelligent driving, assisted driving, intelligent connected vehicles, or indoor commercial scenarios.

[0122] Please refer to Figure 3A This is a schematic diagram of a network architecture applicable to the embodiments of this application, as detailed in 3GPP TS23.501. Figure 3A The network architecture shown can be divided into three parts: the terminal part, the data network (DN), and the carrier network part. The functions of some of these network elements are briefly described below.

[0123] The operator network may include, but is not limited to, one or more of the following network elements: network slice selection function (NSSF) network elements, authentication server function (AUSF) network elements, network exposure function (NEF) network elements, network repository function (NRF) network elements, access and mobility management function (AMF) network elements, policy control function (PCF) network elements, unified data management (UDM) network elements, session management function (SMF) network elements, access network (AN) or radio access network (RAN), and user plane function (UPF) network elements. The portion of the operator network excluding the radio access network portion can be referred to as the core network portion. In one possible implementation, the operator network may also include application function (AF) network elements.

[0124] The UE can establish a connection with the operator's network through interfaces provided by the operator's network (such as N1), and use data and / or voice services provided by the operator's network, such as IMS services. The UE can also access the DN through the operator's network, and use operator services deployed on the DN, and / or services provided by third parties. These third parties can be service providers outside of the operator's network and terminal equipment, and can provide other data and / or voice services to the terminal equipment. The specific form of these third parties can be determined according to the actual application scenario and is not limited here.

[0125] RAN (Radio Access Network) is a subnetwork of a carrier network, serving as the implementation system between service nodes and terminal devices within the carrier network. For a terminal device to access the carrier network, it first passes through the RAN, and then connects to the carrier network's service nodes via the RAN.

[0126] The AMF (Automatic Mobility Management) network element primarily performs functions such as mobility management and access authentication / authorization. Additionally, it is responsible for transmitting user policies between the UE and the PCF (Programmable Component Filter).

[0127] The SMF network element mainly performs functions such as session management, execution of control policies issued by the PCF, selection of the UPF, and allocation of Internet Protocol (IP) addresses for the UE.

[0128] UPF network elements, as interfaces with the data network, perform functions such as user plane data forwarding, session / flow-based billing and statistics, and bandwidth limiting.

[0129] UDM network elements are mainly responsible for managing contract data, user access authorization, and other functions.

[0130] The NSSF network element is primarily responsible for managing information related to network slicing.

[0131] NEF network elements are primarily used to support the opening of capabilities and events.

[0132] AF (Application Provider) network elements primarily convey application-side requests to the network side, such as Quality of Service (QoS) requirements or user state event subscriptions. AF can be a third-party functional entity or an application service deployed by the operator, such as IMS (Information Management Service).

[0133] The PCF network element is primarily responsible for policy control functions such as billing, QoS bandwidth assurance, mobility management, and UE policy decision-making at the session and service data stream levels. In this architecture, the PCFs connected to the AMF and SMF correspond to the AM PCF (PCF for Access and Mobility Control) and SM PCF (PCF for Session Management), respectively, but may not be the same PCF entity in actual deployment scenarios.

[0134] NRF network elements can be used to provide network element discovery functionality, providing network element information corresponding to the network element type based on requests from other network elements. NRF also provides network element management services, such as network element registration, updates, deregistration, and network element status subscription and push.

[0135] AUSF network element: mainly responsible for authenticating users to determine whether to allow users or devices to access the network.

[0136] A Domain Provider (DN) is a network located outside of the carrier's network. A carrier's network can connect to multiple DNs, and various services can be deployed on a DN, providing data and / or voice services to terminal devices. For example, a DN might be the private network of a smart factory. Sensors installed in the workshop can act as terminal devices, and a control server for these sensors is deployed within the DN. The control server provides services to the sensors. Sensors can communicate with the control server, receive instructions from it, and transmit the collected sensor data back to the control server accordingly. Another example is a DN serving as an internal office network for a company. Employees' mobile phones or computers can act as terminal devices, accessing information and data resources on the company's internal office network.

[0137] Figure 3A Nnssf, Nausf, Nnef, Nnrf, Namf, Npcf, Nsmf, Nudm, Naf, N1, N2, N3, N4, and N6 are interface sequence numbers. The meanings of these interface sequence numbers can be found in the definitions in the 3GPP standard protocols, and are not limited here.

[0138] Please refer to Figure 3B This is a schematic diagram of another network architecture applicable to the embodiments of this application, see 3GPP TS23.401 for details. Figure 3B The network architecture shown can be divided into three parts: the terminal part, the PDN, and the carrier network part. The functions of some of these network elements are briefly described below.

[0139] The operator network may include, but is not limited to, one or more of the following network elements: UTRAN, MME, Home Subscriber Server (HSS), Serving Gateway (SGW), Packet Data Network Gateway (PGW), Policy and Charging Rules Function (PCRF) network element, and IMS Application Server (AS).

[0140] UTRAN stands for Access Network Equipment, equivalent to RAN in a 5G network. PDN stands for Packet Data Network, equivalent to DN in a 5G network. Therefore, for relevant introductions to UE, UTRAN, and DN, please refer to [link to relevant documentation]. Figure 3A The introduction of UE, RAN and DN in the code will not be repeated here.

[0141] PCRF network elements primarily perform dynamic QoS policy control and dynamic flow-based charging control functions, while also providing authorization control functions based on user subscription information.

[0142] The MME is a key control node in the LTE access network, mainly responsible for paging idle mode UEs and marking processes, including retransmissions.

[0143] SGW has functions such as local mobility anchoring for inter-base station handover, mobility anchoring for inter-3GPP mobility, packet routing and forwarding, transport level packet marking, and consideration of inter-carrier billing.

[0144] The PGW acts as a connection point to provide transport between the UE and the PDN. A UE can access multiple PDNs simultaneously through multiple PGWs. The PGW implements control policy enforcement, user-specific packet filtering, billing, lawful detection, and packet screening.

[0145] HSS: The core database for storing user information, including subscription details, and also provides a management interface.

[0146] Figure 3B Uu, S1, S6a, S10, S11, S5, Gx, Rx, and SGi are interface sequence numbers. The meanings of these interface sequence numbers can be found in the definitions in the 3GPP standard protocols, and are not limited here.

[0147] The methods provided in the embodiments of this application are described below with reference to the accompanying drawings. In the drawings corresponding to the various embodiments of this application, all steps indicated by dashed lines are optional steps. The various embodiments herein can be applied to... Figure 3A or Figure 3B The architecture shown. For example, the first core network element described in the various embodiments of this document can be... Figure 3A The AMF shown here has a second core network element. Figure 3A The SMF shown here has the following access network element: Figure 3A The RAN shown is a terminal device. Figure 3A The UE shown. Alternatively, the first core network element described in the various embodiments of this document can be... Figure 3B The MME shown has a second core network element. Figure 3B The SGW shown is an access network element. Figure 3B The UTRAN shown here has the following terminal equipment: Figure 3B The UE shown.

[0148] This application provides a communication method, please refer to the embodiments therein. Figure 4 This is a flowchart of the method. In the embodiments of this application, the various embodiments described herein are used. Figure 3B The architecture shown is an example.

[0149] S401: The second core network element sends the first information to the first core network element. Correspondingly, the first core network element receives the first information.

[0150] The first piece of information is IMS-related data, which may be IMS signaling (such as session initiation protocol (SIP) signaling, such as invite messages, 183 messages, 200 messages, 180 ringing messages, etc.), or IMS service data, which may include voice data, video data, holographic call data, or text data, etc. In the following embodiments, IMS-related data is taken as IMS service data.

[0151] In this embodiment, the IMS service data is transmitted through the control plane. Transmission through the control plane can be understood as transmission through control plane network elements, or transmission through a control plane PDN connection (e.g., a PDN connection using / applying to / supporting control plane cellular IoT evolved packet system optimization), or transmission through a control plane session. In this embodiment, IMS service data is transmitted through a control plane PDN connection as an example; that is, in the following embodiments, IMS service data and IMS-related data can be used interchangeably.

[0152] For example, the IMS service data is data sent from the IMS system or the peer terminal of an IMS call to the terminal device, and the terminal device is an NB-IoT device, for example, the RAT type of the terminal device is NB-IoT. Optionally, the terminal device does not support establishing DRBs, or the number of DRBs available to the terminal device is 0. Therefore, the terminal device needs to transmit IMS service data through the control plane. The fact that the number of DRBs available to the terminal device is 0 can also be understood as the terminal device having no available DRBs. Additionally, the fact that the number of DRBs available to the terminal device is 0 indicates that the terminal device may support establishing DRBs, but the established DRBs have been occupied by other services. In this embodiment, an NB-IoT device that does not support establishing DRBs or has 0 available DRBs is used as an example, but this does not limit the scope of protection of the present invention. It also applies to terminal devices that support establishing DRBs or have a number of DRBs that are not 0.

[0153] Optionally, upon receiving the first information, the first core network element can further determine the information type of the first information, or determine whether the first information is IMS service data, for example, whether the first information is control signaling or IMS service data. If the first core network element determines that the first information is control signaling or not IMS service data, the first core network element can send the first information to the access network element, thereby the access network element can send the first information to the terminal device through SRB1bis; if the first core network element determines that the first information is IMS service data, S402 can be executed. It is understood that when the first core network element determines that the first information is control signaling or not IMS service data, it will not send the second information described in the following embodiments when sending the first information to the access network element.

[0154] Optionally, the first core network element can determine the information type of the first information based on the connection identifier corresponding to the first information and / or the address information of the terminal device. For example, the PDN connection in the control plane includes a first PDN connection for transmitting control signaling and a second PDN connection for transmitting IMS service data. If the connection identifier corresponding to the first information indicates the first PDN connection, it indicates that the information type of the first information is control signaling or not IMS-related data; if the connection identifier corresponding to the first information indicates the second PDN connection, it indicates that the information type of the first information is IMS service data.

[0155] The connection identifier may include, for example, one or more of the following: a PDN connection identifier and / or a tunnel identifier. The tunnel identifier, for example, is the identifier of the tunnel established between the first core network element and the second core network element when establishing a control plane PDN connection for transmitting IMS service data (e.g., the aforementioned first PDN connection). This tunnel identifier may be, for example, a tunnel endpoint identifier (TEID) on the first core network element side, or it may be a TEID on the second core network element side. Taking an MME as the first core network element and an SGW as the second core network element, the tunnel identifier may be the MME TEID, or it may be the SGW TEID on the control plane. Optionally, the access point name (APN) corresponding to the first PDN connection is the APN for the IMS service.

[0156] Alternatively, the first core network element can determine the information type of the first information according to the instruction of the second core network element. For example, the second core network element can send the second information to the first core network element to instruct the first information to be transmitted through the SRB corresponding to the RLC mode that does not support retransmission mechanism.

[0157] The first core network element can determine the information type of the first information (or whether the first information is IMS service data) based on whether it receives the second information. For example, if the first core network element receives the second information from the second core network element, it indicates that the information type of the first information is IMS service data; if the first core network element does not receive the second information from the second core network element, or if the first core network element receives signaling indication information from the second core network element, it indicates that the information type of the first information is control signaling. The RLC mode that does not support retransmission mechanisms can be, for example, a transparent mode or an unacknowledged mode. The RLC mode that does not support retransmission mechanisms can also be understood as the RLC entity operating in a mode that does not support retransmission mechanisms. For example, the same SRB may correspond to multiple RLC entities, including RLC entities operating in a mode that supports retransmission mechanisms and RLC entities operating in a mode that does not support retransmission mechanisms.

[0158] Optionally, the second information includes indication information, which indicates that the first information is IMS service data. This indication information indicating that the first information is IMS service data can also be understood as the second information indicating that the first information is IMS service data.

[0159] Optionally, the first information sent by the second core network element to the first core network element is a data packet, and the second information can be carried in the header of the data packet, or the second information can be sent separately from the first information. When the second information is sent separately from the first information, the timing of the second information transmission can be the same as the timing of the first information transmission, i.e., the second core network element sends both the first and second information to the first core network element simultaneously; or the timing of the second information transmission can be different from the timing of the first information transmission. For example, the second core network element can send the first information to the first core network element first, and then send the second information to the first core network element, or vice versa. This embodiment does not limit the timing of the transmission of the first and second information.

[0160] Optionally, the first core network element can also send third information to the second core network element, instructing the second core network element to send the second information when sending IMS service data. That is, the second core network element sending the second information to the first core network element can be instructed by the first core network element. This third information can, for example, be carried in a create session request message. It is understood that instructing the second core network element to send the second information when sending IMS service data is one example of the third information. The third information can also be indication information instructing the second core network element to send information indicating the type of IMS service data when sending IMS service data; this embodiment does not limit this. In this embodiment, "create" and "establish" have the same meaning and can be used interchangeably.

[0161] S402: The first core network element sends first information and second information to the access network element. Correspondingly, the access network element receives the first information and second information.

[0162] When the first core network element determines that the information type of the first information is IMS service data, it can send the first information and the second information to the access network element. The second information is used to instruct the access network element to transmit the first information through the SRB corresponding to the RLC mode that does not support retransmission mechanism.

[0163] Optionally, the first information is carried in a first NAS message, such as a downlink NAS transport message. The second information can be carried in the first NAS message, or it can be carried in other messages, or the second information can be a special format of a NAS PDU. The following are examples of several ways in which a first core network element sends the first and second information to an access network element.

[0164] Method 1: The first core network element sends a first NAS message to the access network element. This first NAS message includes first information and second information. Specifically, in addition to carrying IMS service data, the first NAS message also carries second information indicating that the IMS service data is transmitted via the SRB corresponding to the RLC mode which does not support retransmission. For example, the first information is transmitted as part of a NAS PDU information element (IE), and the second information is an indication for IMS service IE.

[0165] Method 2: The first core network element sends a first NAS message and second information to the access network element. The first NAS message includes the first information, that is, the first NAS message is only used to carry IMS service data, while the second information, which is used to indicate that the IMS service data is transmitted through the SRB corresponding to the RLC mode that does not support retransmission mechanism, is carried in other messages.

[0166] Method 3: The first core network element sends a first NAS message to the access network element. This first NAS message includes first information, which is carried in a special format container, such as a special format NASPDU. This special format can serve as second information, indicating that the IMS service data should be transmitted through the SRB corresponding to the RLC mode that does not support retransmission. For example, the protocol defines a special NAS PDU format (e.g., IMS NAS PDU or IMSNAS PDU IE) for transmitting IMS service data. Therefore, when the first core network element uses this format of NAS PDU to transmit the first information, the access network element can determine that the information in the NASPDU (i.e., the IMS service data) needs to be transmitted through the SRB corresponding to the RLC mode that does not support retransmission.

[0167] It is understood that when a second core network element sends second information to a first core network element, the second information sent by the second core network element to the first core network element may be the same as or different from the second information sent by the first core network element to the access network element. This application embodiment does not limit this. For example, the second information sent by the second core network element to the first core network element may include indication information, the second information sent by the first core network element to the access network element may be second information including indication information, or the second information sent by the first core network element to the access network element may be in a special NAS PDU format.

[0168] As shown in S401, determining the information type of the first information can be implemented by either a first core network element or a second core network element. When the information type of the first information is determined to be implemented by the second core network element (i.e., the first core network element receives the second information from the second core network element), the first core network element can send the first and second information to the access network element in either method 1 or method 2, meaning the first core network element forwards the first and second information. When the information type of the first information is determined to be implemented by the first core network element (i.e., the first core network element does not receive the second information from the second core network element), the first core network element can send the first and second information to the access network element in any of the methods 1, 2, or 3 described above.

[0169] S403: The access network element determines, based on the second information, to send the first information to the terminal device via the first SRB. Accordingly, the terminal device receives the first information via the first SRB.

[0170] When the access network element receives the second information, it can determine the first SRB based on the second information and send the IMS service data to the terminal device through the first SRB. For example, the access network element can send a NAS message to the terminal device through the first SRB, and the NAS message includes the first information. The RLC mode corresponding to the first SRB is a mode that does not support retransmission mechanisms.

[0171] Optionally, when the terminal device has an uplink transmission requirement, such as when the terminal device determines that it needs to send IMS service data to the IMS, the terminal device can send the uplink IMS service data (e.g., the seventh information) to the access network element through the first SRB. For example, the terminal device can send a second NAS message to the access network element, which includes the seventh information. This second NSA message is, for example, an uplink NAS transport message. Optionally, the second NAS message may also include indication information indicating that the seventh information is IMS service data and not control signaling.

[0172] The first SRB can be a different SRB from any of the SRBs defined in the protocol, namely SRB0, SRB1, SRB2, SRB3, SRB4 or SRB1bis. That is, the first SRB is a newly established SRB dedicated to transmitting IMS service data.

[0173] Alternatively, the first SRB can be a protocol-defined SRB. For example, the first SRB could be SRB0. Alternatively, the first SRB can be a second SRB whose RLC mode is adjusted to transparent or unacknowledged mode. This second SRB could be any of SRB1, SRB2, SRB1bis, SRB3, or SRB4. For example, the first SRB could be SRB1bis whose RLC mode is adjusted to transparent or unacknowledged mode. Alternatively, the first SRB can be a second SRB whose corresponding RLC entity operates in transparent or unacknowledged mode. For example, the RLC entity corresponding to SRB1bis includes a first RLC entity (operating in transparent or unacknowledged mode) and a second RLC entity (operating in acknowledged mode), where the first RLC entity transmits IMS service data, the second RLC entity transmits control signaling, and the first SRB could be SRB1bis that transmits information through the first RLC entity. It is understandable that if the first SRB is a second SRB that transmits information through the first RLC entity, then the access network element sending IMS service data to the terminal device through the first SRB is equivalent to the access network element sending IMS service data to the terminal device through the first RLC entity corresponding to the second SRB.

[0174] The above examples illustrate the process of IMS service data transmission, which will be explained below. Figure 5 The illustrated embodiments are described below. Figure 4 Previous possible implementations of the illustrated embodiment.

[0175] Please refer to Figure 5 This is a flowchart of another communication method provided in an embodiment of this application.

[0176] S501: The first core network element sends the fourth information to the access network element. Correspondingly, the access network element receives the fourth information.

[0177] Optionally, before executing S501, the first core network element can further determine that the terminal device can transmit IMS-related data through the control plane. For example, the first core network element can determine that the terminal device can transmit IMS-related data through the control plane based on the terminal device's indication. For instance, the terminal device can send fifth information to the first core network element, which indicates that the terminal device has the capability to transmit IMS-related data through the control plane, or the fifth information indicates that the terminal device supports IMS services. Optionally, the fifth information may also include indication information indicating that the terminal device does not have an available DRB.

[0178] This fifth piece of information can be carried in an attach request; or it can be carried in a PDN connection setup request sent by the terminal device to the first core network element. For example, this fifth piece of information could be a request from the terminal device to transmit IMS-related data through the control plane.

[0179] Alternatively, the first core network element can also determine whether the terminal device can transmit IMS-related data through the control plane, or whether the terminal device supports IMS services, based on at least one of the terminal device's RAT type information, the terminal device's indication information for access via satellite (e.g., GEO), or the fifth type of information. The RAT type information can be used to determine the type or access type of the terminal device. For example, if the terminal device's RAT type is NB-IoT, the first core network element can determine that the terminal device is an NB-IoT device.

[0180] It is understandable that the RAT type information of the terminal device and the indication information for the terminal device's access via GEO can be sent by the access network element, not by the terminal device itself. That is, the source device sending the RAT type information and the indication information for the terminal device's access via GEO is the access network element, not the terminal device. Therefore, the RAT type information and the indication information for the terminal device's access via GEO are carried in different information elements or messages than the fifth information. Taking the fifth information carried in an attach request as an example, when the access network element forwards an attach request to the first core network element, it can carry the RAT type information and the indication information for the terminal device's access via GEO along with the attach request in different NAS PDUs. Alternatively, the access network element can send the RAT type information and the indication information for the terminal device's access via GEO along with the fifth information through different NAS messages. For example, the access network element can send the RAT type information and the indication information for the terminal device's access via GEO to the first core network element through NAS message 1, and send an attach request to the first core network element through NAS message 2.

[0181] Alternatively, the first core network element can also determine, based on the instructions of the third core network element, that the terminal device can transmit IMS-related data through the control plane. For example, the third core network element can send a sixth message to the second core network element. This sixth message indicates that the terminal device is authorized to transmit IMS-related data through the control plane; for example, this sixth message may be the terminal device's subscription information. For example, the third core network element is... Figure 3BThe HSS shown records the subscription information of the terminal device. The first core network element can determine that the terminal device is authorized to transmit IMS related data through the control plane based on the subscription information of the terminal device sent by the HSS.

[0182] When the first core network element determines that the terminal device has the capability to transmit IMS-related data through the control plane, or determines that the terminal device is authorized to transmit IMS-related data through the control plane, it can determine that the terminal device needs to transmit IMS-related data with the access network element via the SRB corresponding to the RLC that does not support retransmission. The first core network element can then send fourth information to the access network element. This fourth information can, for example, be carried in an initial context setup message or a bearer setup request message.

[0183] The fourth piece of information can be used for any of the following:

[0184] The fourth piece of information is used by access network elements to establish a first SRB dedicated to transmitting IMS service data; or,

[0185] The fourth piece of information is used by access network elements to transmit IMS-related data via SRB0; or,

[0186] The fourth piece of information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission, wherein the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3, or SRB4; or,

[0187] The fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB. The RLC mode of this first RLC entity is a mode that does not support retransmission mechanisms, wherein the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3, or SRB4; or,

[0188] The fourth information is used to configure or enable the first function of the access network element. The first function is used to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism when transmitting IMS related data through the second SRB. The second SRB is any one of SRB1, SRB2, SRB1bis, SRB3 or SRB4.

[0189] Specifically, if the fourth information is used by the access network element to establish a first SRB dedicated to transmitting IMS service data, the access network element can execute S502 and S503 after receiving the fourth information. If the fourth information is used by the access network element to transmit IMS-related data through SRB0, the access network element can execute S504 after receiving the fourth information. If the fourth information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission, the access network element can execute S505 and S506 after receiving the fourth information. If the fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, the access network element can execute S507 and S508 after receiving the fourth information. If the fourth information is used by the access network element to configure or enable a first function, the access network element can execute S509 after receiving the fourth information.

[0190] S502: Access network elements establish the first SRB.

[0191] Wherein, the RLC mode corresponding to the first SRB is either transparent mode or unacknowledged mode. The first SRB established by the access network element in transparent mode or unacknowledged mode may be indicated by the first core network element (e.g., triggered by step S501), or it may be predefined by the protocol, or it may be determined by the access network element itself, or it may be determined by other means. This application embodiment does not limit this.

[0192] If the first SRB establishing the RLC mode as transparent or unacknowledged mode by the access network element is indicated by the first core network element, the first core network element can also send indication information to the access network element to indicate the transparent or unacknowledged mode, or the fourth information can also be used to indicate the transparent or unacknowledged mode. Specifically, the indication information sent by the first core network element to the access network element, which is the same as indicating the transparent or unacknowledged mode, can be carried in the same message as the fourth information; that is, the indication information for indicating the transparent or unacknowledged mode can be carried in the initial contextsetup message or the bearer setup request message. Alternatively, the indication information sent by the first core network element to the access network element, which is the same as indicating the transparent or unacknowledged mode, can also be carried in a different message than the fourth information. This application embodiment does not limit this.

[0193] S503: The access network element sends a first indication message to the terminal device, instructing the terminal device to transmit IMS-related data through the first SRB. Accordingly, the terminal device receives the first indication message.

[0194] S503 is an optional step, whereby the terminal device transmits IMS-related data through the first SRB. This transmission can be predefined by the protocol, determined by the terminal device itself, or determined through other means. This embodiment of the application does not limit this step. For example, if a first SRB different from the second SRB is established, the terminal device can determine that the first SRB is used for transmitting IMS-related data.

[0195] S504: The access network element sends a second instruction message to the terminal device, instructing the terminal device to transmit IMS-related data via SRB0. Accordingly, the terminal device receives this second instruction message.

[0196] S505: The access network element adjusts the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism.

[0197] It is understandable that after the access network element adjusts the RLC mode of the second SRB to a mode that does not support retransmission mechanism, the accuracy of the second SRB transmission control signaling may be low, so the second SRB transmission control signaling may not be applicable.

[0198] S506: The access network element sends a third indication message to the terminal device, instructing the terminal device to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission. Accordingly, the terminal device receives this third indication message.

[0199] S507: The access network element configures the first RLC entity for the second SRB. The working mode of the first RLC entity is a mode that does not support retransmission mechanism.

[0200] For example, an access network element can configure two RLC entities for the second SRB, such as a first RLC entity and a second RLC entity. The first RLC entity operates in a mode that does not support retransmission mechanisms, such as transparent mode or unacknowledged mode, and is used to transmit IMS-related data. The second RLC entity operates in acknowledged mode and is used to transmit control signaling.

[0201] S508: The access network element sends a fourth indication message to the terminal device, instructing the terminal device to transmit IMS-related data through the first RLC entity corresponding to the second SRB. Accordingly, the terminal device receives this fourth indication message.

[0202] S508 is an optional step, whereby the terminal device transmits IMS-related data through the first RLC entity corresponding to the second SRB. This transmission can be predefined by the protocol, determined by the terminal device itself, or determined through other means. This embodiment of the application does not limit this. For example, the second SRB corresponds to two RLC entities (a first RLC entity and a second RLC entity). The first RLC entity operates in a mode that does not support retransmission, while the second RLC entity operates in a mode that supports retransmission. The terminal device can determine that it will transmit IMS-related data through the first RLC entity.

[0203] S509: The access network element sends a fifth indication message to the terminal device, instructing the terminal device to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission when transmitting IMS-related data through the second SRB. The terminal device receives this fifth indication message accordingly.

[0204] When transmitting IMS-related data via the second SRB, the RLC mode corresponding to the second SRB is adjusted to a mode that does not support retransmission. This allows the terminal device or access network element to determine the RLC mode corresponding to the second SRB each time it transmits information, based on the information type. This reduces the communication latency of IMS-related data while ensuring the accuracy of control information transmission.

[0205] The aforementioned second, third, fourth, or fifth indication information may, for example, be carried in an RRC connection reconfiguration message.

[0206] Figure 5 In the illustrated embodiment, the example is a first core network element instructing an access network element to establish a first SRB, transmit IMS-related data through SRB0, adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission, and configure the first RLC entity to transmit IMS-related data or configure or enable the first function. In other embodiments, there may be other implementation methods. For example, the terminal device can instruct the access network element to establish a first SRB, transmit IMS-related data through SRB0, adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission, configure the first RLC entity to transmit IMS-related data, or configure or enable the first function. That is, the fourth information can also be sent from the terminal device to the access network element.

[0207] Alternatively, the access network element can establish the first SRB simultaneously with the establishment of the second SRB. For example, the access network element locally determines to establish the first SRB while establishing SRB 1bis or SRB2. Alternatively, the access network element can establish the first SRB after the NAS security establishment is completed. Alternatively, the access network element can also determine to establish the first SRB based on the RRC connection establishment completion message or the NAS security establishment completion message from the terminal device.

[0208] Alternatively, IMS-related data can be transmitted via SRB0 as defined in the protocol.

[0209] Alternatively, the access network element can be configured to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission when it determines that the terminal device needs to transmit IMS-related data, or when a PDN connection or bearer for transmitting IMS-related data is established, or when it is determined that the terminal device can transmit IMS-related data through the control plane.

[0210] Alternatively, when the access network element determines that the terminal device needs to transmit IMS-related data, or when it has established a PDN connection or bearer for transmitting IMS-related data, or when it determines that the terminal device can transmit IMS-related data through the control plane, it may adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism.

[0211] Alternatively, the protocol defines that when the terminal device indicates to the first core network element that it has the ability to transmit IMS-related data in the control plane, or when it determines that the PDN connection used for transmitting IMS-related data has been established, the RLC mode corresponding to the second SRB is adjusted to a mode that does not support retransmission mechanism.

[0212] Alternatively, when the terminal device indicates to the first core network element that it has the capability to transmit IMS-related data in the control plane, or when it determines that the PDN connection used for transmitting IMS-related data has been established, it adjusts the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism.

[0213] Alternatively, when establishing the second SRB, the access network element configures two RLC entities for the second SRB: one RLC entity for transmitting control signaling and the other RLC entity for transmitting IMS-related data.

[0214] Alternatively, the access network element can be configured with two RLC entities for the second SRB when it is determined that the terminal device needs to transmit IMS-related data, or when a PDN connection or bearer for transmitting IMS-related data is established, or when it is determined that the terminal device can transmit IMS-related data through the control plane. One RLC entity is used to transmit control signaling, and the other RLC entity is used to transmit IMS-related data.

[0215] Alternatively, when the access network element determines that the terminal device needs to transmit IMS-related data, or when a PDN connection or bearer for transmitting IMS-related data is established, or when it determines that the terminal device can transmit IMS-related data through the control plane, it configures two RLC entities for the second SRB: one RLC entity for transmitting control signaling and one RLC entity for transmitting IMS-related data.

[0216] Alternatively, the protocol defines that when the terminal device indicates to the first core network element that it has the ability to transmit IMS-related data in the control plane, or when it determines that the PDN connection used for transmitting IMS-related data has been established, the RLC mode corresponding to the second SRB is adjusted to a mode that does not support retransmission mechanism.

[0217] Alternatively, by defining the protocol, when terminal devices and access network devices need to transmit IMS-related data through the second SRB, the RLC mode corresponding to the second SRB can be adjusted to a mode that does not support retransmission mechanism.

[0218] In the above technical solution, when transmitting IMS-related data through SRB, the IMS-related data can be transmitted through SRB that does not support retransmission mechanism, which can reduce IMS communication latency.

[0219] The following is passed Figure 6 and Figure 7 Two embodiments are introduced, which are as follows: Figure 4 and Figure 5 Two examples of communication methods described in the combined embodiments. Figure 6 and Figure 7 In the embodiment shown, the first core network element is MME, the second core network element is SGW, the access network element is eNB, and the terminal device is UE.

[0220] Please refer to Figure 6 ,for Figure 4 and Figure 5 A flowchart illustrating an example of a communication method described in the combined embodiments. Figure 6 In the illustrated embodiment, the determination of the first information as IMS-related data is implemented by the MME as an example.

[0221] S601: The MME determines that the UE transmits IMS-related data through the control plane.

[0222] Specifically, the MME determines whether the UE transmits IMS-related data through the control plane based on the fifth information sent by the UE, the sixth information sent by the HSS, or the RAT type information. The descriptions of the fifth, sixth, and RAT type information can be found in the corresponding descriptions in S501, and will not be repeated here.

[0223] S602: The MME sends a fourth message to the eNB. The eNB then receives this fourth message.

[0224] The description of the fourth information can be found in S501, and will not be repeated here.

[0225] S603: The eNB performs the first operation based on this fourth information.

[0226] The first operation can be referenced. Figure 5 The operations performed by the access network element in S502 to S509 of the illustrated embodiment. For example, if the fourth information is used by the access network element to establish a first SRB dedicated to transmitting IMS service data, the first operation includes establishing the first SRB and sending first indication information to the UE to instruct the UE to transmit IMS-related data through the first SRB.

[0227] If the fourth information is used by the access network element to transmit IMS-related data through SRB0, the first operation is to send a second indication information to the UE to instruct the UE to transmit IMS-related data through SRB0.

[0228] If the fourth information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission, the first operation includes adjusting the RLC mode corresponding to the second SRB to a mode that does not support retransmission and sending the third indication information to the UE.

[0229] If the fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, the first operation includes configuring two RLC entities for the second SRB, such as a first RLC entity and a second RLC entity, wherein the first RLC entity operates in a mode that does not support retransmission mechanisms, such as a transparent mode or an unacknowledged mode, and is used to transmit IMS-related data; the second RLC entity operates in an acknowledged mode and is used to transmit control signaling; and sending fourth indication information to the UE to instruct the UE to transmit IMS-related data through the first RLC entity corresponding to the second SRB.

[0230] If the fourth information is used for access network element configuration or to enable the first function, the first operation is to send the fifth indication information to the UE, which is used to instruct the UE to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism when transmitting IMS related data through the second SRB.

[0231] S604: The UE sends the seventh information to the eNB via the first SRB. The eNB receives the seventh information accordingly.

[0232] For example, the terminal device can send a second NAS message to the access network element, which includes the seventh information. Optionally, the second NAS message may also include indication information indicating that the seventh information is IMS service data rather than control signaling. The seventh information is IMS-related data sent by the UE to the IMS.

[0233] S605: The eNB sends this seventh message to the MME. Correspondingly, the MME receives this seventh message.

[0234] The eNB can send NAS messages (such as a third NAS message) to the MME, which include a seventh message.

[0235] S606: The MME sends this seventh message to the IMS. Correspondingly, the IMS receives this seventh message.

[0236] The process of the eNB sending the seventh information to the IMS is as follows: the MME sends the seventh information to the SGW, the SGW then sends the seventh information to the PGW, and finally the PGW sends the seventh information to the IMS.

[0237] S607: IMS sends the first message to SGW. Correspondingly, SGW receives the first message.

[0238] The process of IMS sending the first information to SGW is as follows: IMS sends the first information to PGW, and then PGW sends the first information to SGW. The relevant description of the first information can be found in the description of the first information in S401, and will not be repeated here.

[0239] S608: The SGW sends the first message to the MME. The MME then receives this first message.

[0240] The relevant description of S607 can be found in the description of the second core network element sending the first information to the first core network element in S401, and will not be repeated here.

[0241] S609: The MME determines that the first information is IMS-related data based on the connection identifier and / or the UE's address information corresponding to the first information.

[0242] The relevant description of S608 can be found in the description of S401 in which the first core network element can determine that the first information is IMS service data based on the connection identifier and / or the address information of the terminal device corresponding to the first information, which will not be repeated here.

[0243] S610: The MME sends first information and second information to the eNB. Correspondingly, the MME receives the first and second information.

[0244] S611: The eNB determines, based on the second information, to send the first information to the UE via the first SRB.

[0245] The relevant descriptions of S610 and S611 can be found in the descriptions of S402 and S403, and will not be repeated here.

[0246] Please refer to Figure 7 ,for Figure 4 and Figure 5 A flowchart illustrating another example of the communication method described in the combined embodiments. Figure 7 In the illustrated embodiment, the determination of the first information as IMS-related data is implemented by SGW as an example.

[0247] S701: The MME determines that the UE transmits IMS-related data through the control plane.

[0248] The relevant description of S701 can be found in the description of S601, and will not be repeated here.

[0249] S702: The MME sends a third message to the SGW. The SGW then receives this third message.

[0250] The description of the third information can be found in S401, and will not be repeated here.

[0251] S703: The MME sends the fourth message to the eNB. The eNB receives the fourth message accordingly.

[0252] S704: The eNB performs the first operation based on this fourth information.

[0253] S705: The UE sends the seventh information to the eNB via the first SRB. The eNB then receives this seventh information.

[0254] S706: The MME sends this seventh message to the MME. Correspondingly, the MME receives this seventh message.

[0255] S707: The MME sends this seventh message to the IMS. Correspondingly, the IMS receives this seventh message.

[0256] S708: IMS sends the first message to SGW. Correspondingly, SGW receives the first message.

[0257] The descriptions of S703 to S708 can be found in the descriptions of the corresponding steps in S602 to S607, and will not be repeated here. S703 and S702 can be executed simultaneously, or S703 can be executed after S702, or S703 can be executed before S702. This embodiment does not limit the execution order of S702 and S703.

[0258] S709: The SGW sends first information and second information to the MME. Correspondingly, the MME receives the first and second information.

[0259] Optionally, the second information includes indication information, which indicates that the first information is IMS service data. This indication information indicating that the first information is IMS service data can also be understood as the second information indicating that the first information is IMS service data.

[0260] Optionally, the first information sent by the SGW to the MME is a data packet, and the second information can be carried in the header of the data packet, or the second information can be sent separately from the first information. When the second information is sent separately from the first information, the timing of the second information transmission can be the same as the timing of the first information transmission, i.e., the SGW sends both the first and second information to the MME simultaneously; or the timing of the second information transmission can be different from the timing of the first information transmission. For example, the SGW can send the first information to the MME first, and then send the second information to the MME, or the SGW can send the second information to the MME first, and then send the first information to the MME. This embodiment of the application does not limit the timing of the transmission of the first and second information.

[0261] S710: The MME sends first information and second information to the eNB. Correspondingly, the MME receives the first and second information.

[0262] S711: The eNB determines, based on the second information, to send the first information to the UE via the first SRB.

[0263] The relevant descriptions of S710 and S711 can be found in the descriptions of S402 and S403, and will not be repeated here.

[0264] Figure 8 A schematic diagram of a communication device according to an embodiment of this application is provided. The communication device 800 may be... Figures 4-7The first core network element or its circuit system, as shown in any of the embodiments illustrated in the accompanying drawings, is used to implement the method corresponding to the first core network element in the above method embodiments. Alternatively, the communication device 800 may be... Figures 4-7 The access network element or circuit system of any of the embodiments shown in the accompanying drawings is used to implement the method corresponding to the access network element in the above method embodiments. Alternatively, the communication device 800 may be... Figures 4-7 The terminal device or its circuit system, as shown in any of the accompanying drawings, is used to implement the method corresponding to the terminal device in the above method embodiments. Alternatively, the communication device 800 may be... Figures 4-7 The second core network element or its circuit system, as shown in any of the accompanying drawings, is used to implement the method corresponding to the second core network element in the above method embodiments. For example, one such circuit system is a chip system.

[0265] The communication device 800 includes at least one processor 801. The processor 801 can be used for internal processing within the device to implement certain control processing functions. Optionally, the processor 801 includes instructions. Optionally, the processor 801 can store data. Optionally, different processors can be independent devices, located in different physical locations, or located on different integrated circuits. Optionally, different processors can be integrated into one or more processors, for example, integrated on one or more integrated circuits.

[0266] Optionally, the communication device 800 includes one or more memories 803 for storing instructions. Optionally, the memories 803 may also store data. The processor and the memories may be separate or integrated together.

[0267] Optionally, the communication device 800 includes a communication line 802 and at least one communication interface 804. Since the memory 803, communication line 802, and communication interface 804 are all optional, therefore... Figure 8 All are represented by dashed lines.

[0268] Optionally, the communication device 800 may further include a transceiver and / or an antenna. The transceiver can be used to send information to or receive information from other devices. The transceiver may be referred to as a transceiver unit, transceiver circuit, input / output interface, etc., and is used to realize the transmission and reception functions of the communication device 800 via the antenna. Optionally, the transceiver includes a transmitter and a receiver. For example, the transmitter can be used to generate a radio frequency (RF) signal from a baseband signal, and the receiver can be used to convert the RF signal back into a baseband signal.

[0269] The processor 801 may include a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of programs according to the present application.

[0270] Communication line 802 may include a path for transmitting information between the aforementioned components.

[0271] The communication interface 804 uses any transceiver-like device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area network (WLAN), wired access network, etc.

[0272] The memory 803 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. The memory 803 may exist independently and be connected to the processor 801 via communication line 802. Alternatively, the memory 803 may be integrated with the processor 801.

[0273] The memory 803 stores computer execution instructions for implementing the scheme of this application, and its execution is controlled by the processor 801. The processor 801 executes the computer execution instructions stored in the memory 803, thereby realizing... Figures 4-7 The steps performed by the first core network element, the second core network element, the access network element, or the terminal device in any of the embodiments shown in the accompanying drawings.

[0274] Optionally, the computer execution instructions in the embodiments of this application may also be referred to as application code, and the embodiments of this application do not specifically limit this.

[0275] In a specific implementation, as one example, the processor 801 may include one or more CPUs, for example... Figure 8 CPU0 and CPU1 in the CPU.

[0276] In a specific implementation, as one example, the communication device 800 may include multiple processors, such as... Figure 8 Processors 801 and 805 are mentioned. Each of these processors can be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor here can refer to one or more devices, circuits, and / or processing cores used to process data (such as computer program instructions).

[0277] when Figure 8 When the device shown is a chip, such as a chip for a first core network element, a chip for a second core network element, a chip for an access network element, or a chip for a terminal device, the chip includes a processor 801 (and may also include a processor 805), a communication line 802, and a communication interface 804. Optionally, it may include a memory 803. Specifically, the communication interface 804 may be an input interface, pins, or circuits, etc. The memory 803 may be a register, cache, etc. The processor 801 and processor 805 may be a general-purpose CPU, microprocessor, ASIC, or one or more integrated circuits for controlling the execution of a program that controls the communication method of any of the above embodiments.

[0278] This application embodiment can divide the device into functional modules according to the above method example. For example, each function can be divided into its own functional modules, or two or more functions can be integrated into one processing module. The integrated modules can be implemented in hardware or as software functional modules. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods. For example, when dividing the device into functional modules according to each function, Figure 9 This is a schematic diagram of an apparatus. The apparatus 900 can be a first core network element, a second core network element, an access network element, or a terminal device involved in the above-described method embodiments, or it can be a chip of the first core network element, a chip of the second core network element, a chip of the access network element, or a chip of the terminal device. The apparatus 900 includes a processing unit 902 and a transceiver unit 901.

[0279] It should be understood that the device 900 can be used to implement the steps performed by the first core network element, the second core network element, the access network element, or the terminal device in the communication method of the embodiments of this application, and the relevant features can be referred to above. Figures 4-7The embodiments shown in any of the accompanying drawings will not be described in detail here.

[0280] Optional, Figure 9 The functions / implementation process of the transceiver unit 901 and the processing unit 902 can be obtained through Figure 8 The processor 801 in the memory calls computer execution instructions stored in memory 803 to implement the function. Alternatively, Figure 9 The function / implementation process of the processing unit 902 in the middle can be achieved through Figure 8 The processor 801 in the memory calls computer execution instructions stored in the memory 803 to implement this. Figure 9 The function / implementation process of the transceiver unit 901 in the middle can be obtained through Figure 8 It is implemented using the 804 communication interface.

[0281] Optionally, when the device 900 is a chip or circuit, the function / implementation process of the transceiver unit 901 can also be implemented through pins or circuits. Optionally, the transceiver unit 901 may include a transmitting unit and / or a receiving unit, whereby the transmitting unit implements the transmitting function and the receiving unit implements the receiving function; or, the transceiver unit 901 may be an integral module capable of implementing both transmitting and / or receiving functions. Optionally, the transceiver unit 901 can be implemented using a transceiver.

[0282] This application also provides a computer-readable storage medium storing a computer program or instructions. When the computer program or instructions are executed, they implement the methods performed by the first core network element, the second core network element, the access network element, or the terminal device in the aforementioned method embodiments. Thus, the functions described in the above embodiments can be implemented as software functional units and sold or used as independent products. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to it, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0283] This application also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to perform the method executed by the first core network element, the second core network element, the access network element, or the terminal device in any of the foregoing method embodiments.

[0284] This application also provides a processing device, including a processor and an interface; the processor is used to execute the methods executed by the first core network element, the second core network element, the access network element, or the terminal device involved in any of the above method embodiments.

[0285] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0286] The various illustrative logic units and circuits described in the embodiments of this application can be implemented or operate the described functions using a general-purpose processor, digital signal processor (DSP), ASIC, field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The general-purpose processor can be a microprocessor; alternatively, it can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented using a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0287] The steps of the methods or algorithms described in the embodiments of this application can be directly embedded in hardware, software units executed by a processor, or a combination of both. The software units can be stored in RAM, flash memory, ROM, erasable programmable read-only memory (EPROM), EEPROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium in the art. Exemplarily, the storage medium can be connected to the processor so that the processor can read information from the storage medium and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. The processor and storage medium can be disposed in an ASIC, which can be disposed in the terminal device. Optionally, the processor and storage medium can also be disposed in different components of the terminal device.

[0288] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0289] The contents of the various embodiments of this application can be referenced to each other. Unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0290] It is understood that in the embodiments of this application, at least one of the first core network element, the second core network element, the access network element, or the terminal device can perform some or all of the steps in the embodiments of this application. These steps or operations are merely examples, and other operations or variations thereof can also be performed in the embodiments of this application. Furthermore, the steps can be performed in different orders as presented in the embodiments of this application, and it is not necessary to perform all the operations in the embodiments of this application.

Claims

1. A communication method, characterized in that, Applied to the first core network element, the method includes: Receive first information from the second core network element, wherein the first information is related data of Internet Protocol Multimedia Subsystem (IMS); Send first information and second information to the access network element, wherein the second information is used to instruct the transmission of the first information through the signaling radio bearer SRB corresponding to the Radio Link Control (RLC) mode that does not support retransmission mechanism.

2. The method as described in claim 1, characterized in that, The second information includes indication information, which indicates that the first information is IMS-related data.

3. The method as described in claim 1 or 2, characterized in that, The method further includes: Based on the connection identifier and / or the address information of the terminal device corresponding to the first information, the first information is determined to be IMS related data.

4. The method as described in claim 3, characterized in that, The connection identifier includes: a Packet Data Network (PDN) connection identifier, and / or a tunnel identifier.

5. The method as described in claim 1 or 2, characterized in that, The method further includes: Receive the second information from the second core network element.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: Send a third message to the second core network element, the third message being used to instruct the second core network element to send the second message in the event that the first message has been sent.

7. The method according to any one of claims 1 to 6, characterized in that, Send the first information to the access network element, including: A first non-access stratum (NAS) message is sent to the access network element, the first NAS message including the first information.

8. The method as described in claim 7, characterized in that, The first NAS message also includes the second information.

9. The method according to any one of claims 1 to 8, characterized in that, The method further includes: Send fourth information to the access network element; wherein, The fourth information is used by the access network element to establish a first SRB and transmit IMS-related data through the first SRB. The RLC mode corresponding to the first SRB is a mode that does not support retransmission mechanism; or... The fourth piece of information is used by the access network element to transmit IMS-related data via SRB0; or... The fourth information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission; or, The fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, wherein the RLC mode of the first RLC entity is a mode that does not support retransmission mechanism; or, The fourth information is used to configure or enable the first function of the access network element. The first function is used to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism when transmitting IMS related data through the second SRB. Wherein, the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3 or SRB4.

10. The method according to any one of claims 1 to 9, characterized in that, The method further includes: The terminal device receives a fifth piece of information, which indicates that the terminal device has the ability to transmit IMS-related data through the control plane. The terminal device is the target device corresponding to the first piece of information.

11. The method according to any one of claims 1 to 10, characterized in that, The method further includes: The sixth information is received from the third core network element. The sixth information is used to indicate that the terminal device is authorized to transmit IMS-related data through the control plane. The terminal device is the target device corresponding to the first information.

12. The method as described in claim 10 or 11, characterized in that, The terminal device accesses the network via Internet of Things (IoT) access technology.

13. The method according to any one of claims 10 to 12, characterized in that, The terminal device does not support establishing a Data Radio Bearer (DRB); or, the number of DRBs available to the terminal device is 0.

14. A communication method, characterized in that, Applied to access network elements, the method includes: Receive first information and second information from the first core network element. The first information is Internet Protocol Multimedia Subsystem (IMS) related data. The second information is used to instruct the first information to be transmitted through the Signaling Radio Bearer (SRB) corresponding to the Radio Link Control (RLC) mode that does not support retransmission. Based on the second information, it is determined that the first information is sent to the terminal device through the first SRB, and the RLC mode corresponding to the first SRB is a mode that does not support retransmission mechanism.

15. The method as described in claim 14, characterized in that, The second information includes indication information, which indicates that the first information is IMS-related data; Determining to send the first information to the terminal device via the first SRB based on the second information includes: determining, based on the indication information, to send the first information to the terminal device via the first SRB corresponding to the RLC mode that does not support retransmission.

16. The method as described in claim 14 or 15, characterized in that, Sending the first information to the terminal device includes: Send a first non-access stratum (NAS) message to the terminal device, the first NAS message including the first information.

17. The method according to any one of claims 14 to 16, characterized in that, The method further includes: Receive fourth information from the terminal device or the first core network element; wherein, The fourth information is used by the access network element to establish a first SRB and transmit IMS-related data through the first SRB. The RLC mode corresponding to the first SRB is a mode that does not support retransmission mechanism; or... The fourth piece of information is used by the access network element to transmit IMS-related data via SRB0; or... The fourth information is used by the access network element to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission; or, The fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, wherein the RLC mode of the first RLC entity is a mode that does not support retransmission mechanism; or, The fourth information is used to configure or enable the first function of the access network element. The first function is used to adjust the RLC mode corresponding to the second SRB to a mode that does not support retransmission mechanism when transmitting IMS related data through the second SRB. Wherein, the second SRB is any one of SRB1, SRB2, SRB1bis, SRB3 or SRB4.

18. The method as described in claim 17, characterized in that, The fourth information is used by the access network element to configure a first RLC entity for transmitting IMS-related data for the second SRB, and to send the first information to the terminal device through the first SRB, including: The first information is sent to the terminal device through the first RLC entity corresponding to the second SRB.

19. The method according to any one of claims 14 to 18, characterized in that, The terminal device accesses the network via Internet of Things (IoT) access technology.

20. The method according to any one of claims 14 to 19, characterized in that, The terminal device does not support establishing a Data Radio Bearer (DRB); or, the number of DRBs available to the terminal device is 0.

21. A communication system, characterized in that, include: First core network element and second core network element.

22. The communication system as described in claim 21, characterized in that, Also includes: Third core network element.

23. A communication device, characterized in that, It includes a processor and a memory, the memory and the processor being coupled, the processor being configured to invoke computer instructions in the memory to execute the method as described in any one of claims 1 to 13, or to execute the method as described in any one of claims 14 to 20.

24. A computer-readable storage medium, characterized in that, Includes a computer program that, when run on a computer, causes the computer to perform the method as described in any one of claims 1 to 13, or causes the computer to perform the method as described in any one of claims 14 to 20.

25. A computer program product, characterized in that, When it is run on a computer, it causes the computer to perform the method as described in any one of claims 1 to 13, or causes the computer to perform the method as described in any one of claims 14 to 20.

26. A chip system, characterized in that, include: A processor for calling and running a computer program from memory such that the method described in any one of claims 1 to 13 is implemented, or the method described in any one of claims 14 to 20 is implemented.

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