Communication method and apparatus

Abstract

The present application relates to the technical field of communications, and provides a communication method and apparatus. The method comprises: determining a non-access stratum (NAS) message, wherein the NAS message comprises a message header and user data, the message header comprises a security header type information element, and the security header type information element indicates that the NAS message is used for transmitting the user data; and sending the NAS message.

Description

A communication method and apparatus

[0001] This application claims priority to Chinese Patent Application No. 202411585673.8, filed on November 6, 2024, entitled "A Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0003] In the control plane user data transmission mechanism, user data is transmitted through non-access stratum (NAS) messages, thereby avoiding the establishment of user plane air interface bearers and improving transmission efficiency and network resource utilization. The NAS message includes a message header and user data. The message header includes information cells from at least one of the mobility management and session management protocols, as well as information cells for security protection. The mobility management or session management information cells indicate that the NAS message carries user data.

[0004] However, the large number of cells in mobility management and session management results in a high bit count in the message header. Furthermore, the method of indicating information is not efficient enough. In addition, data transmission efficiency and latency are also affected, for example, data transmission efficiency is low and transmission latency is high. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a communication method and apparatus that can reduce the bit usage of the message header. To achieve the above objective, this application adopts the following technical solution:

[0006] Firstly, a communication method is provided. This method can be executed by a first communication device. The first communication device can be a terminal device, a component within the terminal device (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the terminal device's functions. Alternatively, the first communication device can be a mobility management network element, a component within the mobility management network element (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the mobility management network element's functions. The following description uses the first communication device as the executing entity. The method includes:

[0007] Identify a Non-Access Stratum (NAS) message, which includes a message header and user data. The message header includes a security header type element indicating that the NAS message is used to transmit the user data. Send the NAS message.

[0008] In other words, the security header type information element indicates that the NAS message is used to transmit the user data, thus reusing existing information elements used for security protection. Compared to indicating that the NAS message contains user data through mobility management and session management information elements, this application uses the security header type information element for indication, thereby reducing message header overhead, improving data transmission efficiency, and reducing transmission latency by reusing existing information elements.

[0009] In one possible design, the method is applied to the first communication device. Before determining the NAS message, the method further includes: sending first capability information, the first capability information indicating that the first communication device supports the NAS message, to achieve capability negotiation between different communication devices.

[0010] In one possible design, the first capability information is included in at least one of the following messages: a registration request message, an attachment request message, or a tracking area update (TAU) request message, wherein the first communication device is a terminal device, thereby enabling capability negotiation during the initial registration, registration update, attachment process, or TAU process.

[0011] In one possible design, the first capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message, wherein the first communication device is a mobility management network element, thereby enabling capability negotiation during initial registration, registration update, attachment process, or TAU process.

[0012] In one possible design, sending the NAS message includes: sending the NAS message to a second communication device. Before determining the NAS message, the method further includes: receiving second capability information from the second communication device, the second capability information indicating that the second communication device supports the NAS message, to achieve capability negotiation between different communication devices.

[0013] In one possible design, the second capability information is included in at least one of the following messages: a registration request message, an attachment request message, or a tracking area update (TAU) request message, wherein the second communication device is a terminal device, thereby enabling capability negotiation during the initial registration, registration update, attachment process, or TAU process.

[0014] In one possible design, the second capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message, wherein the second communication device is a mobility management network element, thereby enabling capability negotiation during initial registration, registration update, attachment process, or TAU process.

[0015] Secondly, a communication method is provided. This method can be executed by a second communication device. The second communication device can be a terminal device, a component within the terminal device (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the terminal device's functions. Alternatively, the second communication device can be a mobility management network element, a component within the mobility management network element (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the mobility management network element's functions. The following description uses the second communication device as the executing entity. The method includes:

[0016] Receive a Non-Access Stratum (NAS) message, the NAS message including a message header and user data, the message header including a security header type element, the security header type element indicating that the NAS message is used to transmit the user data. Process the user data according to the security header type element.

[0017] In one possible design, receiving the NAS message includes: receiving the NAS message from a first communication device. Prior to receiving the NAS message, the method further includes: receiving first capability information from the first communication device, the first capability information indicating that the first communication device supports the NAS message.

[0018] In one possible design, the first capability information is included in at least one of the following messages: a registration request message, an attachment request message, or a tracking area update (TAU) request message, wherein the first communication device is a terminal device.

[0019] In one possible design, the first capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message, wherein the first communication device is a mobility management network element.

[0020] In one possible design, the method is applied to the second communication device. Before receiving the NAS message, the method further includes: sending second capability information, the second capability information indicating that the second communication device supports the NAS message.

[0021] In one possible design, the second capability information is included in at least one of the following messages: a registration request message, an attachment request message, or a tracking area update TAU request message, wherein the second communication device is a terminal device.

[0022] In one possible design, the second capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message, wherein the second communication device is a mobility management network element.

[0023] The technical effects of any design method in the second aspect can be seen in the technical effects of any design method in the first aspect, and will not be repeated here.

[0024] In conjunction with the first or second aspect, in one possible design, the security header type information element further indicates one of the following: the NAS message is security-protected; or, the NAS message is integrity-protected; or, the NAS message is integrity-protected and ciphered; or, the NAS message is integrity-protected and partially ciphered, thereby indicating the type of security protection applied to the NAS message. The message header of the security-protected NAS message is also referred to as the security header for the NAS message.

[0025] In conjunction with either the first or second aspect, in one possible design, the structure of the message header is as follows:

[0026] The value of the EPD cell indicates that the NAS message is a 5GMM (Fifth Generation System Mobility Management) message, and the EPD cell occupies A1 bytes.

[0027] The first type information indicates the data type of the user data, and the first type information occupies M1 bits.

[0028] The second type of information indicates the service type of the user data, and the second type of information occupies N1 bits.

[0029] The secure header type cell occupies P1 bits. M1 + N1 + P1 = 8.

[0030] The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C1 bytes.

[0031] The SN indicates the sequence number of the NAS message, and the SN occupies D1 bytes.

[0032] The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q1 bits.

[0033] The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S1 bits.

[0034] The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T1 bits. Q1 + T1 + S1 = 8.

[0035] A1, B1, C1, D1, E1, M1, N1, P1, Q1, S1, and T1 are all positive integers.

[0036] Based on the structure of the message header, it does not carry mobility management information elements and session management information elements, thereby reducing the overhead of the message header.

[0037] In addition, since the value of the EPD cell indicates that the NAS message is a 5GMM message, the NAS message is applicable to the processing flow of the 5G communication system.

[0038] Since the first information type indicates the data type of the user data and the second information type indicates the service type of the user data, the second communication can process the user data in a timely manner based on the first information type or the second information type.

[0039] The MAC can protect the integrity of the NAS messages to improve the security of message transmission.

[0040] The SN indicates the sequence number of the NAS message, thereby preventing retransmission attacks.

[0041] The first identifier is used to identify the security context, which enables security protection of the NAS message, thereby improving the security performance of message transmission.

[0042] The second identifier is used to identify the first session, so as to facilitate the second communication device to receive the user data through the first session.

[0043] Combining the first or second aspect, in one possible design, A1 = B1 = D1 = E1 = 1, C1 = 2 or 4.

[0044] In other words, the MAC address occupies 4 bytes, thus providing high-security integrity protection; alternatively, the MAC address occupies 2 bytes, thus saving on the overhead of the message header. Furthermore, the message header is 8 bytes, resulting in low overhead.

[0045] Combining the first or second aspect, in one possible design, P1 = 4. That is, the security header type cell occupies 4 bits, which helps to reduce the overhead of the message header.

[0046] In conjunction with either the first or second aspect, in one possible design, the structure of the message header is as follows:

[0047] The value of the EPD cell indicates that the NAS message is a 5GMM (Fifth Generation Mobile Management) message, and the EPD cell occupies A2 bytes.

[0048] The number of free bits is M2 bits, and the number of secure header type cells occupies P2 bits. M2 + P2 = 8.

[0049] The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C2 bytes.

[0050] The SN indicates the sequence number of the NAS message, and the SN occupies D2 bytes.

[0051] The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q2 bits.

[0052] The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S2 bits.

[0053] The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T2 bits. Q2 + T2 + S2 = 8.

[0054] A2, B2, C2, D2, E2, M2, P2, Q2, S2, and T2 are all positive integers.

[0055] Based on the structure of the message header, it does not carry mobility management information elements and session management information elements, thereby reducing the overhead of the message header.

[0056] In addition, since the value of the EPD cell indicates that the NAS message is a 5GMM message, the NAS message is applicable to the processing flow of the 5G communication system.

[0057] The MAC can protect the integrity of the NAS messages to improve the security of message transmission.

[0058] The SN indicates the sequence number of the NAS message, thereby preventing retransmission attacks.

[0059] The first identifier is used to identify the security context, which enables security protection of the NAS message, thereby improving the security performance of message transmission.

[0060] The second identifier is used to identify the first session, so as to facilitate the second communication device to receive the user data through the first session.

[0061] Combining the first or second aspect, in one possible design, A2 = B2 = D2 = E2 = 1, C2 = 2 or 4.

[0062] In other words, the MAC address occupies 4 bytes, thus providing a high level of integrity protection. Alternatively, the MAC address occupies 2 bytes, thereby saving on the overhead of the message header. Furthermore, the message header can be 6 or 8 bytes, resulting in low overhead.

[0063] Combining the first or second aspect, in one possible design, M2 = P2 = 4. That is, the security header type cell occupies 4 bits, which helps to reduce the overhead of the message header.

[0064] In conjunction with either the first or second aspect, in one possible design, the structure of the message header is as follows:

[0065] The value of the EPD cell indicates that the NAS message is a 5GMM (5th Generation Mobile Management) message, and the EPD cell occupies A3 bytes.

[0066] The first type information indicates the data type of the user data, and the first type information occupies M3 bits.

[0067] The second type of information indicates the service type of the user data, and the second type of information occupies N3 bits.

[0068] The secure header type cell occupies P3 bits. M3 + N3 + P3 = 8.

[0069] The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C3 bytes.

[0070] The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q3 bits.

[0071] The SN indicates the sequence number of the NAS message, and the SN occupies R3 bits. Q3 + R3 = 8.

[0072] The number of free bits is K3 bits.

[0073] The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S3 bits.

[0074] The second identifier is used to identify the first session, which is used to transmit the user data, and the second identifier occupies T3 bits.

[0075] A3, B3, C3, D3, E3, M3, N3, P3, R3, K3, S3, and T3 are all positive integers, and Q3 is an integer greater than or equal to 0.

[0076] Based on the structure of the message header, it does not carry mobility management information elements and session management information elements, thereby reducing the overhead of the message header.

[0077] In addition, since the value of the EPD cell indicates that the NAS message is a 5GMM message, the NAS message is applicable to the processing flow of the 5G communication system.

[0078] Since the first information type indicates the data type of the user data and the second information type indicates the service type of the user data, the second communication device can process the user data in a timely manner based on the first information type or the second information type.

[0079] The MAC can protect the integrity of the NAS messages to improve the security of message transmission.

[0080] The SN indicates the sequence number of the NAS message, thereby preventing retransmission attacks.

[0081] The first identifier is used to identify the security context, which enables security protection of the NAS message, thereby improving the security performance of message transmission.

[0082] The second identifier is used to identify the first session, so as to facilitate the second communication device to receive the user data through the first session.

[0083] Combining the first or second aspect, in one possible design, A3 = B3 = D3 = E3 = 1, C3 = 2 or 4.

[0084] In other words, the MAC address occupies 4 bytes, thus providing high-security integrity protection; alternatively, the MAC address occupies 2 bytes, thus saving on the overhead of the message header. Furthermore, the message header is 6 bytes, resulting in low overhead.

[0085] Combining the first or second aspect, in one possible design, P3 = 4. That is, the security header type cell occupies 4 bits, which helps to reduce the overhead of the message header.

[0086] In conjunction with either the first or second aspect, in one possible design, the structure of the message header is as follows:

[0087] The value of the EPD cell indicates that the NAS message is a 5GMM (Fifth Generation System Mobility Management) message, and the EPD cell occupies A4 bytes.

[0088] The number of free bits is M4 bits. The secure header type cell occupies P4 bits. M4 + P4 = 8.

[0089] The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C4 bytes.

[0090] The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q4 bits. The SN indicates the sequence number of the NAS message, and the SN occupies R4 bits. Q4 + R4 = 8.

[0091] The second type of information indicates the service type of the user data, and the second type of information occupies K4 bits.

[0092] The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S4 bits.

[0093] The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T4 bits. K4 + S4 + T4 = 8.

[0094] A4, B4, C4, D4, E4, M4, P4, R4, K4, S4, and T4 are all positive integers, and Q4 is an integer greater than or equal to 0.

[0095] Based on the structure of the message header, it does not carry mobility management information elements and session management information elements, thereby reducing the overhead of the message header.

[0096] In addition, since the value of the EPD cell indicates that the NAS message is a 5GMM message, the NAS message is applicable to the processing flow of the 5G communication system.

[0097] The MAC can protect the integrity of the NAS messages to improve the security of message transmission.

[0098] Since the second type of information indicates the service type of the user data, the second communication can process the user data in a timely manner based on the second type of information.

[0099] The SN indicates the sequence number of the NAS message, thereby preventing retransmission attacks.

[0100] The first identifier is used to identify the security context, which enables security protection of the NAS message, thereby improving the security performance of message transmission.

[0101] The second identifier is used to identify the first session, so as to facilitate the second communication device to receive the user data through the first session.

[0102] Combining the first or second aspect, in one possible design, A4 = B4 = D4 = E4 = 1, C4 = 2 or 4.

[0103] In other words, the MAC address occupies 4 bytes, thus providing high-security integrity protection; alternatively, the MAC address occupies 2 bytes, thus saving on the overhead of the message header. Furthermore, the message header is 6 bytes, resulting in low overhead.

[0104] Combining the first or second aspect, in one possible design, M4 = P4 = 4. That is, the security header type cell occupies 4 bits, which helps to reduce the overhead of the message header.

[0105] In conjunction with either the first or second aspect, in one possible design, the structure of the message header is as follows:

[0106] The secure header type cell occupies M5 bits.

[0107] The value of the PD cell indicates that the NAS message is an Evolved Packet System Mobility Management (EMM) message, and the PD cell occupies N5 bits. M5 + N5 = 8.

[0108] The MAC is used for the integrity protection of the NAS messages, and the MAC occupies 5 bytes.

[0109] The SN indicates the sequence number of the NAS message, and the SN occupies C5 bytes.

[0110] The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies P5 bits.

[0111] The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies Q5 bits.

[0112] The second identifier is used to identify the first bearer, which is used to transmit the user data. The second identifier occupies S5 bits. P5 + Q5 + S5 = 8.

[0113] A5, B5, C5, D5, M5, N5, P5, Q5, and S5 are all positive integers.

[0114] Based on the structure of the message header, it does not carry mobility management information elements and session management information elements, thereby reducing the overhead of the message header.

[0115] In addition, since the value of the PD cell indicates that the NAS message is an EMM message, the NAS message is applicable to the processing flow of the 4G communication system.

[0116] The MAC can protect the integrity of the NAS messages to improve the security of message transmission.

[0117] The SN indicates the sequence number of the NAS message, thereby preventing retransmission attacks.

[0118] The first identifier is used to identify the security context, which enables security protection of the NAS message, thereby improving the security performance of message transmission.

[0119] The second identifier is used to identify the first bearer, so as to facilitate the second communication device to receive the user data through the first bearer.

[0120] Combining the first or second aspect, in one possible design, A5 = C5 = D5 = 1, B5 = 2 or 4.

[0121] In other words, the MAC address occupies 4 bytes, thus providing high-security integrity protection; alternatively, the MAC address occupies 2 bytes, thus saving on the overhead of the message header. Furthermore, the message header is 7 bytes, resulting in low overhead.

[0122] Combining the first or second aspect, in one possible design, M5 = N5 = 4. That is, the security header type cell occupies 4 bits, which helps to reduce the overhead of the message header.

[0123] In conjunction with either the first or second aspect, in one possible design, the structure of the message header is as follows:

[0124] The secure header type cell occupies M6 bits.

[0125] The value of the PD cell indicates that the NAS message is an Evolved Packet System Mobility Management (EMM) message, and the PD cell occupies N6 bits. M6 + N6 = 8.

[0126] The MAC is used for the integrity protection of the NAS messages, and the MAC occupies 6 bytes.

[0127] The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies P6 bits.

[0128] The SN indicates the sequence number of the NAS message, and the SN occupies K6 bits. P6 + K6 = 8.

[0129] The second type of information indicates the service type of the user data, and the second type of information occupies R6 bits.

[0130] The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies Q6 bits.

[0131] The second identifier is used to identify the first bearer, which is used to transmit the user data. The second identifier occupies S6 bits. R6 + Q6 + S6 = 8.

[0132] A6, B6, C6, D6, M6, N6, K6, R6, Q6, and S6 are all positive integers, and P6 is an integer greater than or equal to 0.

[0133] Based on the structure of the message header, there is no need to carry mobility management information elements and session management information elements, thereby reducing the overhead of the message header.

[0134] In addition, since the value of the PD cell indicates that the NAS message is an EMM message, the NAS message is applicable to the processing flow of the 4G communication system.

[0135] The MAC can protect the integrity of the NAS messages to improve the security of message transmission.

[0136] The SN indicates the sequence number of the NAS message, thereby preventing retransmission attacks.

[0137] The first identifier is used to identify the security context, which enables security protection of the NAS message, thereby improving the security performance of message transmission.

[0138] Since the second type of information indicates the service type of the user data, the second communication can process the user data in a timely manner based on the second type of information.

[0139] The second identifier is used to identify the first bearer, so as to facilitate the second communication device to receive the user data through the first bearer.

[0140] Combining the first or second aspect, in one possible design, A6 = C6 = D6 = 1, B6 = 2 or 4.

[0141] In other words, the MAC address occupies 4 bytes, thus providing high-security integrity protection; alternatively, the MAC address occupies 2 bytes, thus saving on the overhead of the message header. Furthermore, the message header is 5 bytes, resulting in low overhead.

[0142] Combining the first or second aspect, in one possible design, M6 = N6 = 4. That is, the security header type cell occupies 4 bits, which helps to reduce the overhead of the message header.

[0143] In conjunction with the first or second aspect, in one possible design, the message header length is less than or equal to 8 bytes.

[0144] In other words, the message header length does not exceed 8 bytes, resulting in low message header overhead.

[0145] In conjunction with the first or second aspect, in one possible design, the first type of information indicates that the data type of the user data is one of the following: control plane user data, short message, location service data, or terminal device policy information.

[0146] In conjunction with the first or second aspect, in one possible design, the second type of information indicates that the service type of the user data is one of the following: uplink data transmission, downlink data transmission, or emergency data transmission.

[0147] In conjunction with the first or second aspect, in one possible design, the security header type element indicates that the NAS message is used to transmit the user data. This can be understood as the security header type element indicating that the NAS message is dedicated to transmitting the user data. In other words, the NAS message is a dedicated message.

[0148] Thirdly, a communication device is provided for implementing the various methods described above. The communication device includes modules, units, or means corresponding to the methods, which can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the functions.

[0149] In some possible designs, the communication device may include a processing module and a transceiver module. The processing module can be used to implement the processing functions in any of the above aspects and any possible implementations. The transceiver module, also called a transceiver unit, is used to implement the sending and / or receiving functions in any of the above aspects and any possible implementations. The transceiver module may consist of transceiver circuitry, a transceiver, a transceiver unit, or a communication interface.

[0150] In some possible designs, the transceiver module includes a sending module and / or a receiving module, which are used to implement the sending or receiving functions in any of the above aspects and any possible implementations.

[0151] Fourthly, a communication device is provided for implementing the method in any of the above aspects or any possible design of any aspect.

[0152] Fifthly, a communication device is provided, comprising: a processor; the processor being configured to execute a computer program or instructions to cause the communication device to perform the method described in any one aspect or any possible design in any one aspect.

[0153] Optionally, the communication device further includes a memory, which may be coupled to the processor, or the memory may exist independently of the processor; for example, the memory and the processor may be two separate modules. The memory may be located outside or inside the communication device.

[0154] Sixthly, a computer-readable storage medium is provided. This computer-readable storage medium stores a computer program or instructions that, when executed, cause the methods described in any of the foregoing aspects or any possible design of any of the foregoing aspects to be implemented.

[0155] In a seventh aspect, a computer program product containing instructions is provided, which, when run, causes the method described in any of the foregoing aspects or any possible design in any of the foregoing aspects to be implemented.

[0156] The communication device provided in any of the third to seventh aspects can be the first communication device of the first aspect, or a component included in the first communication device, such as a chip or chip system; or it can be the second communication device of the second aspect, or a component included in the second communication device, such as a chip or chip system. When the device is a chip system, it can be composed of chips or can include chips and other discrete devices.

[0157] It is understandable that when the communication device provided by any of the third to seventh aspects is a chip, the sending action / function of the communication device can be understood as outputting information, and the receiving action / function of the communication device can be understood as inputting information.

[0158] Eighthly, a communication apparatus is provided for implementing the method described in any of the preceding aspects or any possible design method in any of the preceding aspects. Optionally, the communication apparatus includes a terminal device, a mobility management network element, a chip system, or a chip.

[0159] The technical effects of any of the design methods in aspects three through eight can be found in the technical effects of any of the design methods in aspects one through two, and will not be repeated here. Attached Figure Description

[0160] Figure 1 is a schematic diagram of the architecture of a communication system provided in an embodiment of this application;

[0161] Figure 2 is a schematic diagram of the architecture of another communication system provided in an embodiment of this application;

[0162] Figure 3 is a schematic diagram of the architecture of another communication system provided in an embodiment of this application;

[0163] Figure 4 is a schematic diagram of a communication protocol stack provided in an embodiment of this application;

[0164] Figure 5 is a flowchart illustrating a communication method provided in an embodiment of this application;

[0165] Figure 6 is a flowchart illustrating another communication method provided in an embodiment of this application;

[0166] Figure 7 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0167] Figure 8 is a schematic diagram of another communication device provided in an embodiment of this application;

[0168] Figure 9 is a schematic diagram of the structure of another communication device provided in an embodiment of this application. Detailed Implementation

[0169] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0170] The network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0171] Figure 1 is a schematic diagram of the architecture of a communication system provided in an embodiment of this application. As shown in Figure 1, the communication system includes a terminal device, an access network device, and a core network device. The access network device and the core network device can be collectively referred to as network devices. The access network device can also be called a radio access network (RAN) device.

[0172] The terminal equipment includes devices that provide voice and / or data connectivity to users. Specifically, it includes devices that provide voice connectivity to users, or devices that provide data connectivity to users, or devices that provide both voice and data connectivity to users. For example, it may include a handheld device with wireless connectivity or a processing device connected to a wireless modem. This terminal equipment can communicate with the core network via a radio access network (RAN), exchanging voice or data with the RAN, or interacting with the RAN for both voice and data. The terminal equipment may include user equipment (UE), wireless terminal equipment, mobile terminal equipment, device-to-device (D2D) terminal equipment, vehicle-to-everything (V2X) terminal equipment, machine-to-machine / machine-type communications (M2M / MTC) terminal equipment, Internet of Things (IoT) terminal equipment, subscriber unit, subscriber station, mobile station, remote station, access point (AP), remote terminal, access terminal, user terminal, user agent, or user device, etc. For example, it may include mobile phones (or "cellular" phones), computers with mobile terminal devices, portable, pocket-sized, handheld, or computer-embedded mobile devices, etc. Examples include personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, and personal digital assistants (PDAs). It also includes limited devices, such as those with low power consumption, limited storage capacity, or limited computing power. Examples include information sensing devices such as barcode scanners, radio frequency identification (RFID), sensors, global positioning systems (GPS), and laser scanners.

[0173] The various terminal devices described above, if located in a vehicle (e.g., placed inside or installed inside a vehicle), can be considered as vehicle-mounted terminal devices, also known as on-board units (OBUs).

[0174] In this embodiment, the terminal device may further include a relay. Alternatively, it can be understood that anything capable of data communication with a base station can be considered a terminal device.

[0175] In this application embodiment, the device for implementing the functions of the terminal device can be the terminal device itself, or it can be a device capable of supporting the terminal device in implementing the functions, such as a chip system, which can be installed in the terminal device. In this application embodiment, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in this application embodiment, the terminal device is used as an example to illustrate the device for implementing the functions of the terminal.

[0176] Access network equipment can be access points for wireless or wired communication, such as base stations or base station controllers, wireless-fidelity (Wi-Fi) access points or Wi-Fi controllers, or fixed-line access points, etc. The base station can include various types of base stations, such as micro base stations (also known as small stations), macro base stations, relay stations, access points, etc., but this application embodiment does not specifically limit this. In the embodiments of this application, the base station may be a base transceiver station (BTS) in Global System for Mobile Communication (GSM), a base station (node ​​B) in Wideband Code Division Multiple Access (WCDMA), an evolved node B (eNB or e-NodeB) in Long Term Evolution (LTE), an eNB in ​​Internet of Things (IoT), Narrow Band Internet of Things (NB-IoT), Broadband Internet of Things, or Satellite Internet of Things, a base station in the fifth generation (5G) mobile communication network, or a future evolved public land mobile network (PLMN). The embodiments of this application do not impose any limitations on this.

[0177] There can be various types of core network equipment. For example, core network equipment may include a mobility management entity (MME), as shown in Figure 2. Alternatively, core network equipment may include core access and mobility management function (AMF) network elements, as shown in Figure 3.

[0178] For example, Figure 2 illustrates a schematic diagram of the architecture of a fourth-generation (4G) communication system. This 4G communication system includes Evolved UMTS Territorial Radio Access Network (E-UTRAN) equipment, MME, Serving Gateway (SGW), Packet Data Network (PDN) Gateway (PGW), Policy and Charging Rules Function (PCRF) network elements, and Home Subscriber Server (HSS) and other network elements or equipment.

[0179] Specifically, the terminal device accesses the E-UTRAN device via LTE-Uu, the E-UTRAN device communicates with the MME via S1-MME, the E-UTRAN device communicates with the SGW via S1-U, different MMEs communicate with each other via S10 (Figure 2 only shows one MME as an example), the MME communicates with the HSS via S6a, the MME communicates with the SGW via S11, the SGW communicates with the PGW via S5, the PGW communicates with the PCRF network element via Gx, the PCRF network element communicates with the server via Rx, and the PGW accesses the server via SGi.

[0180] The E-UTRAN equipment is used to implement radio-related functions of the evolved network. The MME is responsible for mobility management on the control plane, including user context and mobility state management, and assigning temporary user identities. The SGW is the user plane anchor point between 3GPP access networks and serves as the interface for terminating E-UTRAN. The PGW is the user plane anchor point between 3GPP and non-3GPP access networks and serves as the interface for terminating external PDNs. PCRF network elements are used for policy control decisions and flow charging control functions. The HSS stores user subscription information. Servers provide Internet Protocol (IP) services, such as voice / video services and packet-switched streaming services (PSS) based on the Internet Protocol Multimedia Subsystem (IMS).

[0181] Optionally, for backward compatibility with the general packet radio service (GPRS) data service provided by the 2G / 3G system and better interoperability with the second-generation (2G) / third-generation (3G) communication system, as shown in Figure 2, it also includes UTRAN / global system for mobile communication (GSM) or enhanced data rate for GSM evolution (EDGE) radio access network (GSM / EDGE radio access network, GERAN) equipment of the 2G / 3G communication system and the serving GPRS support node (SGSN). They participate in the inter-system mobility of terminal devices between the 4G communication system and the 2G / 3G communication system, including idle-state mobility and connected-state handover. This will be explained uniformly here and will not be repeated below. When a terminal device accesses a 2G / 3G communication system, the terminal device communicates with the SGSN through the UTRAN / GERAN equipment, the UTRAN / GERAN equipment communicates with the SGW through S12, the SGSN communicates with the MME through S3, and the SGSN communicates with the SGW through S4.

[0182] Optionally, the UTRAN / GERAN equipment in Figure 2 can be, for example, a base station system (BSS) in a 2G communication system or a radio network controller (RNC) in a 3G communication system, without limitation. Furthermore, the E-UTRAN equipment in Figure 2 can be, for example, an evolved node B (eNodeB), without limitation.

[0183] Optionally, the network architecture shown in Figure 2 may also include other network elements, such as policy and charging rules function (PCRF) network elements, etc., without limitation.

[0184] For example, Figure 3 shows a schematic diagram of the architecture of a fifth-generation (5G) communication system. The 5G communication system includes radio access network (RAN) equipment, user plane function (UPF) network elements, network slice-specific authentication and authorization function (NSSAAF) network elements, authentication server function (AUSF) network elements, AMF network elements, session management function (SMF) network elements, service communication function (SCP) network elements, network slice admission control function (NSACF) network elements, network slice selection function (NSSF) network elements, network exposure function (NEF) network elements, network exposure function repository function (NRF) network elements, policy control function (PCF) network elements, unified data management (UDM) network elements, application function (AF) network elements, and edge application server discovery function (EASDF) network elements.

[0185] It should be noted that Figure 3 is only an example of some network elements or entities in a 5G communication system. The 5G communication system may also include network data analytics function (NWDAF) network elements and other network elements or entities not shown in Figure 3. This application embodiment does not make specific limitations on this.

[0186] As shown in Figure 3, the terminal device accesses the 5G network through the RAN device. The terminal device communicates with the AMF network element through the N1 interface (N1); the RAN device communicates with the AMF network element through the N2 interface (N2); the RAN device communicates with the UPF network element through the N3 interface (N3); the SMF network element communicates with the UPF network element through the N4 interface (N4); the UPF network element accesses the data network (DN) through the N6 interface (N6); and different UPF network elements communicate with each other through the N9 interface (N9). In the architecture shown in Figure 3, N1, N2, N3, N4, N6, and N9 represent reference points between relevant network elements / network functions.

[0187] In addition, the control plane functions of the NSSAAF, AUSF, AMF, SMF, SCP, NSACF, NSSF, NEF, NRF, PCF, UDM, AF, or EASDF network elements shown in Figure 3 interact using service-oriented interfaces. For example, the service interface provided by the NSSAAF network element is Nnssaaf; the service interface provided by the AUSF network element is Nausf; the service interface provided by the AMF network element is Namf; the service interface provided by the SMF network element is Nsmf; the service interface provided by the NSACF network element is Nnsacf; the service interface provided by the NSSF network element is Nnssf; the service interface provided by the NEF network element is Nnef; the service interface provided by the NRF network element is Nnrf; the service interface provided by the PCF network element is Npcf; the service interface provided by the UDM network element is Nudm; the service interface provided by the AF network element is Naaf; and the service interface provided by the EASDF network element is Neasdf. Related functional and interface descriptions can be found in the 5G system architecture diagram in the 3GPP standard, and will not be elaborated upon here.

[0188] For example, Figure 4 illustrates a schematic diagram of a communication protocol stack. As shown in Figure 4, the protocol stack on the terminal device side includes at least the following layers: Non-access stratum (NAS), Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and Physical (PHY) layer. Among these, the RRC, PDCP, RLC, MAC, and PHY layers all belong to the access stratum (AS).

[0189] The Non-Access Layer (NAL) is a functional layer between the terminal equipment and the core network equipment, used to support signaling and data transmission between the terminal equipment and core network elements (such as MME or AMF network elements, or other mobility management network elements). In other words, the NAL is the interface protocol between the terminal equipment and core network equipment (such as mobility management network elements). The RRC layer supports functions such as radio resource management and RRC connection control. For the definitions and functions of other protocol layers, such as the PDCP layer and RLC layer, please refer to the relevant 3GPP technical specifications; they will not be elaborated upon here.

[0190] It should be understood that the names of the aforementioned core network devices, such as the MME and AMF network elements, are merely names and do not constitute a limitation on the devices themselves. It is understood that other names may be used in 5G communication systems and other future networks, and this application does not specifically limit this. For example, an AMF network element may also be called an AMF or an AMF entity; this will be explained uniformly here and will not be repeated below.

[0191] Optionally, the core network equipment can be implemented by a single device, multiple devices working together, or a functional module within a single device; this application does not specifically limit this. It is understood that the aforementioned functional module can be a network element in a hardware device, a software functional module running on dedicated hardware, or a virtualized functional module instantiated on a platform (e.g., a cloud platform).

[0192] It should be understood that the applicable scenarios for the embodiments of this application include cellular Internet of Things (IoT), such as narrowband IoT, broadband IoT, and satellite IoT.

[0193] To facilitate understanding of the embodiments of this application, the terminology used in the embodiments of this application will be briefly explained below. It should be understood that these explanations are only for the purpose of understanding the embodiments of this application and should not constitute any limitation on this application.

[0194] 1. Control plane user data transmission

[0195] In the 3GPP technical specifications, the user plane is mainly used to transmit user data, while the control plane is mainly used to transmit control signaling. For example, when a terminal device transmits user data through the user plane, after initiating an initial NAS message and entering the connected state, it establishes a user plane bearer context (including the user plane air interface bearer). The terminal device can then send user data to the RAN device, which forwards the user data to the user plane function (UPF) network element. For IoT terminal devices, data transmission is optimized. For example, user data can be transmitted through the control plane. This means that IoT terminal devices can transmit data by carrying user data in NAS messages from the control plane, avoiding the establishment of the user plane air interface bearer and improving the efficiency of user data transmission and network resource utilization. This mechanism can also be called the Data over NAS mechanism.

[0196] In this application, the data transmitted via NAS messages will be referred to as user data, or control plane user data, or control plane data, or cellular Internet of Things (CIoT) control plane data, or CIoT user data, or simply data. The following section will use user data as an example.

[0197] 2. 4G CIoT Control Plane User Data Transmission Mechanism

[0198] In 4G communication systems, the 3GPP 4G NAS protocol defines NAS messages for control plane user data transmission:

[0199] First, for the idle state, this NAS message is a Control Plane Service Request (CPSR) message, used in the mobility management service request process, employing a two-layer protocol nesting. The nested two-layer protocols include the mobility management protocol and the session management protocol.

[0200] The CPSR message, as shown in Table 1a, has a header of 18 bytes, meaning that the header overhead is 18 bytes, specifically including:

[0201] The 6-byte security header overhead indicates the required information elements in the security header, such as the security header type, protocol discriminator (PD), message authentication code (MAC), and sequence number (SN). The security header type indicates the type of security protection for the NAS message, such as integrity-protected NAS message, integrity-protected and ciphered NAS message, or integrity-protected and partially ciphered NAS message. Different values ​​for the security header type correspond to different security protection types for the NAS message; refer to relevant technical specifications. The protocol discriminator indicates that the NAS message is an Evolved Packet System (EPS) Mobility Management (EMM) message. The message authentication code is used for integrity protection of the NAS message, and the sequence number indicates the transmission order of the NAS message.

[0202] A 6-byte Mobility Management Message Header overhead is used to indicate the required elements in the Mobility Management Message Header, such as the EMM header and the Evolved Packet System (EPS) Session Management (ESM) Message Container Information Element header.

[0203] A 6-byte session management message header overhead is used to indicate the required elements in the session management message header, such as the ESM message header and the user data container information element header.

[0204] Table 1a

[0205] It should be understood that in this application, the NAS message header can also be called the NAS protocol header; the two have the same meaning and can be used interchangeably.

[0206] Second, for the connected state, this NAS message is an ESM data transfer message, used in the control plane user data transfer process, employing a nested Layer 1 protocol. The nested Layer 1 protocol includes the session management protocol. The ESM data transfer message can be denoted as ESM DATA TRANSPORT.

[0207] The ESM DATA TRANSPORT message in the connection state is shown in Table 1b. The message header is 12 bytes (octets), meaning that the message header overhead is 12 bytes, specifically including:

[0208] The 6-byte security protection header overhead indicates the required information elements in the security protection header, such as security header type, protocol discriminator (PD), message authentication code (MAC), and sequence number (SN).

[0209] A 6-byte session management message header overhead is used to indicate the required elements in the session management message header, such as the ESM message header, user data container information element header, etc.

[0210] Table 1b

[0211] 3. 5G CIoT Control Plane User Data Transmission Mechanism

[0212] In 5G communication systems, the 3GPP 5G NAS protocol has made some protocol optimizations for control plane user data transmission, mainly including:

[0213] First, for the idle state, control plane user data is transmitted through control plane service request (CPSR) messages, using a single layer of protocol nesting, thereby reducing message header overhead.

[0214] Second, for the connected state, user data is transmitted through uplink non-access stratum transport (UL NAS TRANSPORT) messages or downlink non-access stratum transport (DL NAS TRANSPORT) messages, which also adopts a layer 1 protocol nesting, thereby reducing message header overhead.

[0215] Third, for small data packets (such as data packets with a length of less than or equal to 254 bytes), a dedicated cellular IoT small data container is used for encapsulation, which can be transmitted in the idle state.

[0216] For large data packets (such as data packets with a length greater than 254 bytes), a payload container is used for encapsulation, which can be transmitted in idle state or connected state.

[0217] The NAS messages encapsulated using the CIoT small data container are shown in Table 1c. The message header is 14 bytes (octets), meaning that the message header overhead is 14 bytes, specifically including:

[0218] The 7-byte security protection header overhead indicates the required elements in the security protection header, such as the extended protocol discriminator (EPD), security header type, message authentication code (MAC), and sequence number (SN).

[0219] A 4-byte mobility management message header overhead is used to indicate the required cells in the mobility management message header, such as the fifth generation system (5GS) mobility management messages (5GMM) message header.

[0220] The 3-byte information elements (IE) header overhead includes elements such as the cellular IoT small packet container information element header, data type, downlink data expectation, and PDU session identifier. The data type indicates the data type of the user data. The downlink data expectation indicates whether downlink data transmission is expected after the user data transmission. The PDU session identifier identifies a PDU session used for transmitting user data.

[0221] Table 1c

[0222] The CPSR message encapsulated using the Payload container is shown in Table 1d. The message header is 17 bytes long, meaning that the message header overhead is 17 bytes, specifically including:

[0223] The 7-byte security protection header overhead indicates the required elements in the security protection header, such as the extended protocol discriminator (EPD), security header type, message authentication code (MAC), and sequence number (SN).

[0224] A 4-byte Mobility Management header overhead is used to indicate the required elements in the Mobility Management header, such as the 5GMM header.

[0225] The 3-byte mandatory IE header overhead includes elements such as the payload container type, PDU session identifier, and payload container information element header.

[0226] Table 1d

[0227] The UL / DL NAS TRANSPORT message encapsulated using a payload container is shown in Table 1e. The message header is 15 bytes long, meaning the header overhead is 15 bytes, specifically including:

[0228] The 7-byte security protection header overhead indicates the required elements in the security protection header, such as the extended protocol discriminator (EPD), security header type, message authentication code (MAC), and sequence number (SN).

[0229] A 4-byte Mobility Management header overhead is used to indicate the required elements in the Mobility Management header, such as the 5GMM header.

[0230] Two bytes of other mandatory IE header overhead, and two bytes of IE header overhead such as PDU session identifier, payload container information element header, etc.

[0231] Table 1e

[0232] In summary, the overhead of the 4G / 5G CIoT control plane user data transmission head is shown in Table 1f:

[0233] Table 1f

[0234] As shown in Table 1f, in infrequent small data packet transmission scenarios for low-cost, low-power IoT terminal devices, the message header overhead is significant, reducing the efficiency of small data packet transmission. This is especially true for satellite IoT access, where satellite link quality and air interface transmission latency are worse than those of terrestrial cellular networks. Furthermore, even within terrestrial cellular networks, the air interface link quality and air interface transmission latency of narrowband IoT (NB-IoT) access are worse than those of ordinary broadband cellular access, while NB-IoT is a mandatory option for supporting control plane user data transmission.

[0235] In other words, in the 4G / 5G CIoT control plane user data transmission mechanism, NAS messages employ nested Layer 1 or Layer 2 protocols. The nested protocols include at least one of mobility management and session management protocols. In other words, the message header includes not only security protection information elements but also mobility management or session management information elements. On the receiving side, the user data carried by the NAS message is determined based on the mobility management or session management information elements. This can be understood as the mobility management or session management information elements indicating that the NAS message contains user data.

[0236] In summary, in the 4G / 5G CIoT control plane user data transmission mechanism, the NAS message header includes not only security protection cells but also mobility management or session management cells, which indicate that the NAS message contains user data. However, the large number of mobility management and session management cells results in high message header overhead, low data transmission efficiency, and high transmission latency.

[0237] In view of this, this application provides a communication method. This method can be applied to systems such as those shown in Figures 1 to 3. The method includes:

[0238] Identify the NAS message, which includes a message header and user data. The message header includes a security header type element indicating that the NAS message is used to transmit user data. Send the NAS message.

[0239] In other words, for security header type information elements, in addition to their use for security protection, they can also indicate that the NAS message is used to transmit user data. That is, the same information element can indicate more information, thereby reusing existing information elements used for security protection. Compared with the method of indicating that the NAS message contains user data through mobility management and session management information elements, this application uses security header type information elements for indication, thereby reusing existing information elements, reducing message header overhead, improving data transmission efficiency, and reducing transmission latency.

[0240] It should be noted that the user data transport described in this application can also be referred to as carrying user data, containing user data, or encapsulating user data.

[0241] The communication method proposed in this application embodiment will now be described in detail with reference to Figure 5. The communication method 500 proposed in this application embodiment includes the following operations:

[0242] S501, The first communication device confirms the NAS message.

[0243] The first communication device can be a terminal device as shown in Figures 1 to 3, or a core network device as shown in Figures 1 to 3, such as a mobility management network element. For example, a mobility management network element can be an MME in a 4G communication system. As another example, a mobility management network element can be an AMF network element in a 5G communication system.

[0244] The NAS message includes a header and user data. The user data is carried in the data payload of the NAS message, as shown in Table 2 or Table 3.

[0245] The message header is described as follows:

[0246] The message header includes a security header type element.

[0247] The security header type element indicates that the NAS message is used to transmit user data. For example, the security header type element may have a new value, indicating that the NAS message is used to transmit user data. For instance, the new value of the security header type element could be 1101, suitable for 4G or 5G communication systems. Alternatively, for 5G communication systems, the new value of the security header type element could be 1101 or 1100.

[0248] Optionally, the security header type information element may also indicate one of the following: the NAS message is security-protected; or, the NAS message is integrity-protected; or, the NAS message is integrity-protected and ciphered; or, the NAS message is integrity-protected and partially ciphered, thereby indicating the type of security protection applied to the NAS message. The message header of a security-protected NAS message may also be referred to as a security header for the NAS message. In this application, the message header is used as an example for description.

[0249] Optionally, in a 5G communication system, the security header type cell occupies f1 bits, where f1 is a positive integer, as shown in Table 2. For example, f1 = 4. That is, the security header type cell occupies 4 bits.

[0250] Optionally, in a 4G communication system, the security header type cell occupies e2 bits, where e2 is a positive integer, as shown in Table 3. For example, e2 = 4. That is, the security header type cell occupies 4 bits.

[0251] Optionally, in this application, the NAS message is used to transmit user data, which can be understood as the NAS message being dedicated solely to transmitting user data. For example, if the security header type element indicates that the NAS message is used to transmit user data, it means that the security header type element indicates that the NAS message is dedicated solely to transmitting user data.

[0252] Optionally, the message header may also include an EPD cell or a PD cell.

[0253] The value of the EPD cell indicates that the NAS message is a 5GMM message. This means that the NAS message can be used as a 5GMM message in the processing flow of a 5G communication system, conforming to the basic principles of the NAS protocol. As shown in Table 2, the EPD cell occupies a1 bytes, where a1 is a positive integer. For example, a1 = 1. That is, the EPD cell occupies 1 byte.

[0254] The value of the PD cell indicates that the NAS message is an EMM message. This means that the NAS message can be used as an EMM message in the processing flow of the 4G communication system, conforming to the basic principles of the NAS protocol. As shown in Table 3, the PD cell occupies f2 bits, where f2 is a positive integer. For example, f2 = 4. That is, the PD cell occupies 4 bits.

[0255] Optionally, the message header may also include at least one of a message authentication code (MAC) and a sequence number (SN), wherein the MAC is used for integrity protection of the NAS message and the SN indicates the sequence number of the NAS message.

[0256] As shown in Table 2, the MAC occupies c1 bytes, where c1 is a positive integer.

[0257] For example, c1 = 4. That is to say, the MAC occupies 4 bytes, which can be understood as a long MAC to provide higher security and integrity protection.

[0258] For example, c1 = 2. That is to say, the MAC occupies 2 bytes, which can be understood as a short MAC to save the overhead of the message header.

[0259] Similarly, taking Table 3 as an example, b2 = 2 or 4.

[0260] As shown in Table 2, SN occupies g1 bits, where g1 is a positive integer.

[0261] For example, g1 = 8. That is, SN occupies 8 bits, or 1 byte (i.e., d1 = 1). It can be understood that SN is a long SN, which more accurately indicates the sending order of the NAS message.

[0262] For example, g1 = 5. That is to say, SN occupies 5 bits, which can be understood as SN being a short SN to save the overhead of the message header.

[0263] Similarly, taking Table 3 as an example, g2 = 5 or 8.

[0264] It should be understood that in this application, Table 2 shows a message header structure for a NAS message applicable to the processing flow of a 5G communication system. Table 3 shows another message header structure for a NAS message applicable to the processing flow of a 4G communication system.

[0265] Table 2

[0266] It should be understood that in Table 2, a1, b1, c1, d1, e1, f1, and g1 are all positive integers. For example, a1 = b1 = d1 = 1, c1 = 2 or 4, e1 = f1 = 4, and g1 = 5 or 8.

[0267] Table 3

[0268] It should be understood that in Table 3, a2, b2, c2, e2, f2, and g2 are all positive integers. For example, a2 = b2 = 1, c2 = 2 or 4, e2 = f2 = 4, and g2 = 5 or 8.

[0269] It should be understood that in this application, the message header of the NAS message also contains some spare bits. As shown in Table 2, the byte containing the security header type has some spare bits. As shown in Table 2 or Table 3, when the SN is a short SN, the byte containing the short SN may also have some spare bits. Based on this, the message header also includes other information elements, which are described in detail below:

[0270] Optionally, the message header may also include at least one of a first type of information and a second type of information.

[0271] The first type of information indicates the data type of the user data. For example, the first type of information indicates that the data type of the user data is one of the following: control plane user data, short message, location service data, or terminal device policy information. The terminal device policy information can be referred to as UE policy information. For example, the first type of information is included in the data type information element, occupying 2 or 3 bits.

[0272] The second type of information indicates the service type of the user data. For example, the second type of information indicates that the service type of the user data is one of the following: uplink data transmission, downlink data transmission, or emergency data transmission. Uplink data transmission refers to the terminal device initiating (mobile originating, MO) the NAS message. Downlink data transmission refers to the NAS message sent to the terminal device, i.e., mobile terminating (MT), used for paging response. For example, the second type of information is included in the service type information element, occupying 2 or 3 bits.

[0273] Optionally, the message header may also include at least one of downlink data expected (DDX), a first identifier, and a second identifier.

[0274] DDX indicates whether downlink data transmission is expected after user data transmission. For example, when the user data is uplink data, DDX is used to indicate single-shot or single-shot+single ack.

[0275] In this application, "single-shot" means that no uplink or downlink data transmission occurs after the user data transmission is completed; that is, the end of the user data transmission signifies the end of the transmission process. In other words, the DDX cell value is 01 to indicate that there is no further uplink data transmission, nor is there any further downlink data transmission following the uplink data transmission (i.e., No further uplink and no further downlink data transmission subsequent to the uplink data transmission is expected).

[0276] In this application, "single-shot + single ack" means that downlink data transmission occurs after the user data transmission is completed. This downlink data transmission includes ACK transmission. For example, the DDX cell occupies 2 or 3 bits. In other words, the DDX cell value is 10 to indicate that only one downlink data transmission occurs, and no further uplink data transmission is expected after the uplink data transmission.

[0277] Additionally, DDX can also be 00, indicating that no information about DDX is carried. If received, it should be interpreted as "neither value '01' nor value '10' applies".

[0278] The first identifier identifies the security context, which is used for the security protection of NAS messages. For example, the security context includes a security key, which is used for encrypting or decrypting NAS messages.

[0279] For example, in a 4G communication system, the first identifier is called the key set identifier (KSI), which occupies 3 bits.

[0280] For example, in a 5G communication system, the first identifier is called the next generation key set identifier (ngKSI), which occupies 3 bits.

[0281] The second identifier is used to identify the first session or the first bearer. The first session and the first bearer are used to transmit the user data.

[0282] For example, in a 4G communication system, the second identifier is the identifier of the first bearer, which is included in the Evolved Packet System Bearer Identity (EPS) cell and occupies 3 bits.

[0283] For example, in a 5G communication system, the second identifier is the identifier of the first session, which is included in the Protocol Data Unit Session Identity (PDU) information element and occupies 3 bits.

[0284] Optionally, the message header length is less than or equal to 8 bytes. Compared to the message header overhead in Table 1f, the message header overhead of this NAS message is reduced.

[0285] It should be understood that in this application, the message header also includes at least one of first type information, second type information, DDX, first identifier, and second identifier, and the position and length of the first type information, second type information, DDX, first identifier, and second identifier in the message header are not limited. Next, the structure of the message header will be described using six examples (Examples 1-6 below):

[0286] Example 1, the message header structure is shown in Table 4a:

[0287] Table 4a

[0288] As shown in Table 4a, the bytes or bits occupied by each information cell are as follows:

[0289] The value of the EPD cell indicates that the NAS message is a 5GMM message, and the EPD cell occupies A1 bytes.

[0290] The first type of information indicates the data type of the user data, occupying M1 bits. The second type of information indicates the service type of the user data, occupying N1 bits. The security header type information cell occupies P1 bits. Furthermore, M1 + N1 + P1 = 8.

[0291] MAC is used for integrity protection of NAS messages, and MAC occupies C1 bytes.

[0292] SN indicates the sequence number of the NAS message. SN occupies D1 bytes.

[0293] The first identifier identifies the security context, which is used for the security protection of NAS messages. This identifier occupies Q1 bits. The DDX indicates whether downlink data transmission is expected after user data transmission; it occupies S1 bits. The second identifier identifies the first session, which is used to transmit user data; it occupies T1 bits. Furthermore, Q1 + T1 + S1 = 8.

[0294] Among them, parameters A1, B1, C1, D1, E1 and P1 are all positive integers, and M1, N1, Q1, S1 and T1 are all integers greater than or equal to 0.

[0295] Furthermore, A1 = B1 = D1 = E1 = 1, C1 = 2 or 4. That is to say, the EPD cell occupies 1 byte, the MAC cell occupies 2 or 4 bytes, and the SN cell occupies 1 byte.

[0296] Furthermore, P1 = 4. That is, the security header type occupies 4 bits.

[0297] Furthermore, based on M1+N1+P1=8, the following possible implementation methods can be included: M1=N1=2, P1=4; or, M1=1, N1=3, P1=4; or, M1=3, N1=1, P1=4.

[0298] Furthermore, based on Q1+T1+S1=8, the following possible implementations can be included: Q1=T1=3, S1=2; or, Q1=T1=4, S1=0; or, Q1=T1=2, S1=4. It should be understood that the parameters Q1, T1, and S1 can also have other values, as long as Q1+T1+S1=8 is satisfied.

[0299] It should be understood that the positions of Type 1 information, Type 2 information, DDX, Type 1 identifier, and Type 2 identifier in the message header in Table 4a are presented as examples, and the positions of each information element in the message header can be interchanged. For example, the positions of Type 1 information and Type 2 information can be interchanged, or the positions of Type 1 identifier and Type 2 identifier can be interchanged, or the positions of identifier (such as Type 1 identifier or Type 2 identifier) ​​and DDX can be interchanged, or the positions of identifier (such as Type 1 identifier or Type 2 identifier) ​​and type information (such as Type 1 information or Type 2 information) can be interchanged.

[0300] Optionally, for Table 4a, when A1=B1=D1=E1=1 and C1=4, it means that the message header overhead of the NAS message is a total of 8 bytes. Compared with the 5G NAS message header overhead shown in Table 1f, the message header overhead of this application is reduced by 6-9 bytes.

[0301] Example 2, the message header structure is shown in Table 4b:

[0302] Table 4b

[0303] As shown in Table 4b, the bytes or bits occupied by each information cell are as follows:

[0304] The value of the EPD cell indicates that the NAS message is a 5GMM message, and the EPD cell occupies A2 bytes.

[0305] There are M² bits of free space. The secure header type cell occupies P² bits. Therefore, M² + P² = 8.

[0306] MAC is used for integrity protection of NAS messages, and MAC occupies C2 bytes.

[0307] SN indicates the sequence number of the NAS message. SN occupies D2 bytes.

[0308] The first identifier identifies the security context, which is used for the security protection of NAS messages. This identifier occupies Q2 bits. The DDX indicates whether downlink data transmission is expected after user data transmission; it occupies S2 bits. The second identifier identifies the first session, which is used to transmit user data; it occupies T2 bits. Therefore, Q2 + T2 + S2 = 8.

[0309] Where A2, B2, C2, D2, E2 and P2 are all positive integers, and M2, Q2, S2 and T2 are all integers greater than or equal to 0.

[0310] Furthermore, A2 = B2 = D2 = E2 = 1. And C2 = 2 or 4. That is to say, the EPD cell occupies 1 byte, the MAC cell occupies 2 or 4 bytes, and the SN cell occupies 1 byte.

[0311] Furthermore, M2 = P2 = 4. That is, the security header type occupies 4 bits, with half a byte of space.

[0312] Furthermore, based on Q2+T2+S2=8, the following possible implementation methods can be included: Q2=T2=3, S2=2; or, Q2=T2=4, S2=0; or, Q2=T2=2, S2=4. It should be understood that the parameters Q2, T2, and S2 can also have other values, as long as Q2+T2+S2=8 is satisfied.

[0313] It should be understood that the positions of DDX, the first identifier, and the second identifier in the message header in Table 4b are presented as examples, and the positions of each information element in the message header can be interchanged. For example, the positions of the first identifier and the second identifier can be interchanged, or the positions of the identifier (such as the first identifier or the second identifier) ​​and DDX can be interchanged. In addition, the positions of the aforementioned information elements (such as DDX, the first identifier, and the second identifier) ​​can also be interchanged with the positions of the idle bits.

[0314] Optionally, for Table 4b, when A2=B2=D2=E2=1 and C2=4, it means that the message header overhead of the NAS message is a total of 8 bytes. Compared with the 5G NAS message header overhead shown in Table 1f, the message header overhead of this application is reduced by 6-9 bytes.

[0315] Example 3, the message header structure is shown in Table 4c:

[0316] Table 4c

[0317] As shown in Table 4c, the bytes or bits occupied by each information cell are as follows:

[0318] The value of the EPD cell indicates that the NAS message is a 5GMM message, and the EPD cell occupies A3 bytes.

[0319] The first type of information indicates the data type of the user data, occupying M3 bits. The second type of information indicates the service type of the user data, occupying N3 bits. The security header type information cell occupies P3 bits. Therefore, M3 + N3 + P3 = 8.

[0320] MAC is used for integrity protection of NAS messages, and MAC occupies C3 bytes.

[0321] The first identifier is used to identify the security context, which is used for the security protection of NAS messages. The first identifier occupies Q3 bits. The SN indicates the sequence number of the NAS message, and the SN occupies R3 bits. Furthermore, Q3 + R3 = 8.

[0322] The free bits are K3 bits. DDX indicates whether downlink data transmission is expected after user data transmission; DDX occupies S3 bits. The second identifier is used to identify the first session, which is used to transmit user data; the second identifier occupies T3 bits. Furthermore, K3 + T3 + S3 = 8.

[0323] Among them, A3, B3, C3, D3, E3, R3 and P3 are all positive integers, and M3, N3, Q3, K3, S3 and T3 are all integers greater than or equal to 0.

[0324] Furthermore, A3 = B3 = D3 = E3 = 1, and C3 = 2 or 4. That is to say, the EPD cell occupies 1 byte, and the MAC cell occupies 2 or 4 bytes.

[0325] Furthermore, P3 = 4. That is, the security header type cell occupies 4 bits.

[0326] Furthermore, based on M3+N3+P3=8, the following possible implementation methods can be included: M3=N3=2, P3=4; or, M3=1, N3=3, P3=4; or, M3=3, N3=1, P3=4.

[0327] Furthermore, based on Q3 + R3 = 8, the following possible implementations can be included: Q3 = 3, R3 = 5; or, Q3 = 4, R3 = 45; or, Q3 = 0, R3 = 8. It should be understood that parameters Q3 and R3 can also have other values, as long as Q3 + R3 = 8 is satisfied.

[0328] Furthermore, based on K3+T3+S3=8, the following possible implementation methods can be included: K3=S3=2, T3=4; or, K3=S3=3, T3=2; or, K3=S3=4, T3=0. It should be understood that the parameters K3, T3, and S3 can also have other values, as long as K3+T3+S3=8.

[0329] It should be understood that in Table 4c, the positions of the first type of information, the second type of information, DDX, the first identifier, and the second identifier in the message header are presented as examples. The positions of each information element in the message header can be interchanged, as described in Table 4a, and will not be repeated here. In addition, the free bit can also be interchanged with the above information elements (such as the first type of information, the second type of information, DDX, the first identifier, and the second identifier).

[0330] Optionally, for Table 4c, when A3=B3=D3=E3=1 and C3=2, it means that the message header overhead of the NAS message is a total of 6 bytes. Compared with the 5G NAS message header overhead shown in Table 1f, the message header overhead of this application is reduced by 8-11 bytes.

[0331] Example 4, the message header structure is shown in Table 4d:

[0332] Table 4d

[0333] As shown in Table 4d, the bytes or bits occupied by each information cell are as follows:

[0334] The value of the EPD cell indicates that the NAS message is a 5GMM message, and the EPD cell occupies A4 bytes.

[0335] There are M4 free bits. The secure header type cell occupies P4 bits. Therefore, M4 + P4 = 8.

[0336] MAC is used for integrity protection of NAS messages, and MAC occupies C4 bytes.

[0337] The first identifier is used to identify the security context, which is used for the security protection of NAS messages. The first identifier occupies Q4 bits. The SN indicates the sequence number of the NAS message, and the SN occupies R4 bits. Furthermore, Q4 + R4 = 8.

[0338] The second type of information indicates the service type of the user data, occupying K4 bits. DDX indicates whether downlink data transmission is expected after user data transmission, occupying S4 bits. The second identifier is used to identify the first session, which is used to transmit user data; this identifier occupies T4 bits. Furthermore, K4 + S4 + T4 = 8.

[0339] Among them, A4, B4, C4, D4, E4, R4 and P4 are all positive integers, and M4, Q4, K4, S4 and T4 are all integers greater than or equal to 0.

[0340] Furthermore, A4 = B4 = D4 = E4 = 1, and C4 = 2 or 4. That is to say, the EPD cell occupies 1 byte, and the MAC cell occupies 2 or 4 bytes.

[0341] Furthermore, M4 = P4 = 4. That is, the security header type occupies 4 bits, with half a byte of space.

[0342] Furthermore, based on Q4 + R4 = 8, the following possible implementations can be included: Q4 = 3, R4 = 5; or, Q4 = 4, R4 = 4; or, Q4 = 0, R4 = 8. It should be understood that parameters Q4 and R4 can also have other values, as long as Q4 + R4 = 8 is satisfied.

[0343] Furthermore, based on K4+S4+T4=8, the following possible implementations can be included: K4=S4=2, T4=4; or, K4=S4=3, T4=2; or, K4=S4=4, T3=0. It should be understood that the parameters K4, T4, and S4 can also have other values, as long as K4+S4+T4=8 is satisfied.

[0344] It should be understood that in Table 4d, the positions of the second type information, DDX, first identifier, and second identifier in the message header are presented as examples. The positions of each information element in the message header can be interchanged, as described in Table 4a, and will not be repeated here. In addition, the free bit can also be interchanged with the above information elements (such as the second type information, DDX, first identifier, and second identifier).

[0345] Optionally, for Table 4d, when A4=B4=D4=E4=1 and C4=2, it means that the message header overhead of the NAS message is a total of 6 bytes. Compared with the 5G NAS message header overhead shown in Table 1f, the message header overhead of this application is reduced by 8-11 bytes.

[0346] Example 5, the message header structure is shown in Table 4e:

[0347] Table 4e

[0348] As shown in Table 4e, the bytes or bits occupied by each information cell are as follows:

[0349] The security header type cell occupies M5 bits. The PD cell value indicates that the NAS message is an EMM message, and the PD cell occupies N5 bits. Furthermore, M5 + N5 = 8.

[0350] MAC is used for integrity protection of NAS messages, and MAC occupies 5 bytes.

[0351] SN indicates the sequence number of the NAS message. SN occupies C5 bytes.

[0352] The first identifier identifies the security context, which is used for the security protection of NAS messages. This identifier occupies P5 bits. The DDX indicates whether downlink data transmission is expected after user data transmission; it occupies Q5 bits. The second identifier identifies the first bearer, which is used to transmit user data; it occupies S5 bits. Therefore, P5 + Q5 + S5 = 8.

[0353] Among them, A5, B5, C5, D5, M5 and N5 are all positive integers, and P5, Q5 and S5 are all integers greater than or equal to 0.

[0354] Furthermore, A5 = C5 = D5 = 1, and B5 = 2 or 4. That is, the MAC address occupies either 2 or 4 bytes. The SN address occupies 1 byte.

[0355] Furthermore, M5 = N5 = 4. That is, the security header type cell occupies 4 bits. The PD cell occupies 4 bits.

[0356] Furthermore, based on P5+Q5+S5=8, the following possible implementations can be included: P5=S5=3, Q5=2; or, P5=S5=2, Q5=4; or, P5=S5=4, Q5=0. It should be understood that the parameters P5, Q5, and S5 can also have other values, as long as P5+Q5+S5=8.

[0357] It should be understood that the positions of DDX, the first identifier, and the second identifier in the message header in Table 4e are presented as examples. The positions of each information element in the message header can be interchanged, as can be seen in Table 4a, and will not be repeated here.

[0358] Optionally, for Table 4e, when A5=C5=D5=1 and B5=4, it means that the message header overhead of the NAS message is a total of 7 bytes. Compared with the 4G NAS message header overhead shown in Table 1f, the message header overhead of this application is reduced by 5-11 bytes.

[0359] Example 6, the message header structure is Table 4f:

[0360] Table 4f

[0361] As shown in Table 4e, the bytes or bits occupied by each information cell are as follows:

[0362] The security header type cell occupies M6 bits. The PD cell value indicates that the NAS message is an EMM message, and the PD cell occupies N6 bits. Furthermore, M6 + N6 = 8.

[0363] MAC is used for integrity protection of NAS messages, and MAC occupies 6 bytes.

[0364] The first identifier is used to identify the security context, which is used for the security protection of NAS messages. The first identifier occupies P6 bits. The SN indicates the sequence number of the NAS message, and the SN occupies K6 bits. Furthermore, P6 + K6 = 8.

[0365] The second type of information indicates the service type of the user data, occupying R6 bits. DDX indicates whether downlink data transmission is expected after user data transmission, occupying Q6 bits. The second identifier identifies the first bearer, which is used to transmit user data, occupying S6 bits. Furthermore, R6 + Q6 + S6 = 8.

[0366] Among them, A6, B6, C6, D6, K6, M6 and N6 are all positive integers, and P6, R6, Q6 and S6 are all integers greater than or equal to 0.

[0367] Furthermore, A6 = C6 = D6 = 1, and B6 = 2 or 4. That is to say, the MAC occupies 2 bytes or 4 bytes.

[0368] Furthermore, M6 = N6 = 4. That is, the security header type cell occupies 4 bits. The PD cell occupies 4 bits.

[0369] Furthermore, based on P6+K6=8, the following possible implementations can be included: P6=3, K6=5; or, P6=4, K6=4; or, P6=0, K6=8. It should be understood that parameters P6 and K6 can also have other values, as long as P6+K6=8.

[0370] Furthermore, based on R6+Q6+S6=8, the following possible implementation methods can be included: R6=Q6=2, S6=4; or, R6=Q6=3, S6=2; or, R6=Q6=4, S6=0. It should be understood that the parameters R6, Q6, and S6 can also have other values, as long as R6+Q6+S6=8.

[0371] It should be understood that in Table 4f, the second type of information can also be replaced with the first type of information. Furthermore, the positions of the second type of information, DDX, first identifier, and second identifier in the message header are introduced as examples. The positions of each information element in the message header can be interchanged, as can be seen in the introduction in Table 4a, and will not be repeated here.

[0372] Optionally, for Table 4f, when A6=C6=D6=1 and B6=2, it means that the message header overhead of the NAS message is a total of 5 bytes. Compared with the 4G NAS message header overhead shown in Table 1f, the message header overhead of this application is reduced by 7-13 bytes.

[0373] For the first communication device, after determining the NAS message, it executes S502:

[0374] S502, the first communication device sends a NAS message to the second communication device. Correspondingly, the second communication device receives the NAS message from the first communication device.

[0375] The second communication device can be a terminal device as shown in Figures 1 to 3, or a mobility management network element as shown in Figures 1 to 3.

[0376] Specifically, when the first communication device is a terminal device, the second communication device is a mobility management network element.

[0377] For details on NAS messages, please refer to the introduction of S501, which will not be repeated here.

[0378] For the second communication device, after receiving the NAS message, it executes S503:

[0379] S503, The second communication device processes user data according to the security header type information cell.

[0380] The second communication device can be found in the description of S502, and will not be repeated here.

[0381] For details on the security header type information element and user data, please refer to the introduction in S501, which will not be repeated here.

[0382] For example, the second communication device obtains user data from the NAS message based on the security header type information element, and processes the user data.

[0383] In other words, more information is indicated through security header type cells, thereby reusing existing cells used for security protection. Compared to indicating that the NAS message contains user data through mobility management and session management cells, this application uses security header type cells to indicate this, achieving cell reuse, thereby reducing message header overhead, improving data transmission efficiency, and reducing transmission latency.

[0384] In some embodiments, the first communication device and the second communication device perform capability negotiation. Specifically, as shown in FIG6, this application further includes at least one of S511 and S512:

[0385] S511, the first communication device sends first capability information to the second communication device. Correspondingly, the second communication device receives the first capability information from the first communication device.

[0386] The first capability information indicates that the first communication device supports the aforementioned NAS message.

[0387] For example, if the first communication device is a terminal device and the second communication device is a mobility management network element, then the first capability information is included in at least one of the following messages: registration request message, attachment request message, or tracking area update (TAU) request message.

[0388] For example, if the first communication device is a mobility management network element and the second communication device is a terminal device, then the first capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message.

[0389] In other words, the first communication device and the second communication device negotiate their capabilities during the initial registration, location update registration, attachment, or TAU process to inform each other of their own capabilities.

[0390] S512, the second communication device sends second capability information to the first communication device. Correspondingly, the first communication device receives the second capability information from the second communication device.

[0391] The second capability information indicates that the second communication device supports the aforementioned NAS message.

[0392] For example, if the first communication device is a mobility management network element and the second communication device is a terminal device, the second capability information is included in at least one of the following messages: registration request message, attachment request message, or tracking area update (TAU) request message.

[0393] For example, if the first communication device is a terminal device and the second communication device is a mobility management network element, then the second capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message.

[0394] In other words, the first communication device and the second communication device negotiate their capabilities during the initial registration, location update registration, attachment, or TAU process to inform each other of their own capabilities.

[0395] Optionally, taking the first communication device as the terminal device and the second communication device as the mobility management network element as an example, in the initial registration process (or registration update process), the first communication device sends the first capability information through the registration request message, and the second communication device sends the second capability information through the registration acceptance message, thereby realizing capability negotiation between the two parties in the registration process.

[0396] Alternatively, taking the first communication device as a mobile management network element and the second communication device as a terminal device as an example, in the initial registration process (or registration update process), the second communication device sends the second capability information through a registration request message, and the first communication device sends the first capability information through a registration acceptance message, thereby realizing capability negotiation between the two parties in the registration process.

[0397] Optionally, taking the first communication device as the terminal device and the second communication device as the mobility management network element as an example, in the attach process, the first communication device sends the first capability information through the attach request message, and the second communication device sends the second capability information through the attach accept message, thereby realizing capability negotiation between the two parties in the attach process.

[0398] Alternatively, taking the first communication device as a mobile management network element and the second communication device as a terminal device as an example, in the attach process, the second communication device sends the second capability information through the attach request message, and the first communication device sends the first capability information through the attach accept message, thereby realizing capability negotiation between the two parties in the attach process.

[0399] Optionally, taking the first communication device as the terminal device and the second communication device as the mobility management network element as an example, in the TAU process, the first communication device sends the first capability information through the TAU request message, and the second communication device sends the second capability information through the TAU receive message, thereby realizing capability negotiation between the two parties in the TAU process.

[0400] Alternatively, taking the first communication device as a mobile management network element and the second communication device as a terminal device as an example, in the TAU process, the second communication device sends the second capability information through the TAU request message, and the first communication device sends the first capability information through the TAU receive message, thereby realizing capability negotiation between the two parties in the TAU process.

[0401] Optionally, control plane user data transmission is performed only if both the first and second communication devices support the aforementioned NAS messages, as described in S501-S503.

[0402] It should be added that the initial registration and location update registration process includes the following steps:

[0403] Step 1: The terminal device sends a registration request message to the mobility management network element. Correspondingly, the mobility management network element receives the registration request message from the terminal device.

[0404] For the mobility management network element, if it accepts the registration request message, it proceeds to step 2:

[0405] Step 2: The mobility management network element sends a registration acceptance message to the terminal device. Accordingly, the terminal device receives the registration acceptance message from the mobility management network element, thus completing the initial registration or location update registration process.

[0406] It should be added that the attachment process includes the following steps:

[0407] Step 3: The terminal device sends an attach request message to the mobility management network element. Correspondingly, the mobility management network element receives the attach request message from the terminal device.

[0408] For the mobility management element, if it accepts the attach request message, it proceeds to step 4:

[0409] Step 4: The mobility management network element sends an attach accept message to the terminal device. Correspondingly, the terminal device receives the attach accept message from the mobility management network element, thus completing the attach procedure.

[0410] It should be added that the TAU process includes the following steps:

[0411] Step 5: The terminal device sends a TAU request message to the mobility management network element. Correspondingly, the mobility management network element receives the TAU request message from the terminal device.

[0412] For the mobility management network element, if the mobility management network element accepts the TAU request message, then it executes step 6:

[0413] Step 6: The mobility management network element sends a TAU acceptance message to the terminal device. Accordingly, the terminal device receives the TAU acceptance message from the mobility management network element, thus completing the attach procedure.

[0414] In some embodiments, the communication method of this application is applicable to both connected and idle states, including uplink transmission and downlink transmission.

[0415] It should be noted that the message name for the NAS message is not limited in this application; for example, see below:

[0416] In some embodiments, the NAS messages in this application use the same message name for all scenarios under the same communication standard.

[0417] For example, in a 5G communication system, the message name of this NAS message is 5GMM Data Transport or Short 5GMM Data Transport.

[0418] For example, in a 4G communication system, the message name of this NAS message is EMM Data Transport or Short EMM Data Transport.

[0419] In some embodiments, the NAS messages in this application may have different message names for different scenarios under the same communication standard.

[0420] For example, in the uplink idle state, the message name of this NAS message is Short Control Plane Service Request (SHORT CONTROL PLANE SERVICE REQUEST).

[0421] For example, in the connected state, for a 5G communication system, the message name of the NAS message is 5GMM Data Transport or Short 5GMM Data Transport; or, for a 4G communication system, the message name of the NAS message is EMM Data Transport or Short EMM Data Transport.

[0422] It should be noted that in this application, the message header includes an EPD element, the value of which indicates that the NAS message is a 5GMM message, applicable to the processing flow of 5G communication systems, and conforms to the basic principles of the NAS protocol. Alternatively, the message header includes a PD element, the value of which indicates that the NAS message is an EMM message, applicable to the processing flow of 4G communication systems, and conforms to the basic principles of the NAS protocol. Compared to the approach of defining new NAS protocols in related technologies, this application aims to design new NAS messages (such as the NAS messages in S501-S503) rather than define new NAS protocols, thereby making the NAS message applicable to the processing flow of either 5G or 4G communication systems, with good compatibility.

[0423] To reduce message header overhead, the technical solution for the new NAS protocol is defined as follows:

[0424] To address the issue of high message header overhead in 4G CIoT NAS, a novel NAS protocol is proposed, specifically designed for transmitting control plane user data. The message encoding of this NAS protocol is shown in Table 5. The message header of this NAS message includes:

[0425] A newly defined 1-byte extended protocol discriminator (EPD) indicates that the NAS message is an Evolved Packet System (EPS) cellular Internet of Things (CIoT) data transmission message (which can be denoted as EPS CIoT data transmission message). Furthermore, the value of the EPD differs from that of the PD, signifying that this NAS protocol differs from the 4G NAS protocol.

[0426] A 4-byte message authentication code (MAC) is used for integrity protection of the NAS message.

[0427] A 1-byte sequence number (SN) indicates the order in which the NAS message was sent.

[0428] One byte of required parameters. These parameters include: a 3-bit EPS bearer ID, a 2-bit downlink data expected (DDX), and a 3-bit key set identifier (KSI). The EPS bearer ID identifies an EPS bearer used to transmit user data. The DDX indicates whether it's a single-slot or single-slot + single ack configuration. A single-slot configuration means that no downlink data transmission is expected after uplink user data transmission, while a single-slot + single ack configuration means that downlink data transmission is expected after uplink user data transmission. Downlink data transmission includes the transmission of an acknowledgment (ACK). The key set identifier identifies the security context of the NAS message, which is used for the security protection of the NAS message.

[0429] Table 5

[0430] As shown in Table 5, this NAS message occupies n bytes, i.e., bytes 1 to byte n. The message header occupies 7 bytes. The extended protocol distinguisher occupies 1 byte, i.e., byte 1. The message authentication code occupies 4 bytes, i.e., bytes 2 to 5. The sequence number occupies 1 byte, i.e., byte 6. The EPS bearer identifier, downlink data expectation, and NAS key set identifier together occupy 1 byte, i.e., byte 7. The data payload occupies the remaining bytes, i.e., bytes 8 to byte n. n is a positive integer.

[0431] It should be noted that while Tables 1c, 1d, 1e, and 5 all involve EPD information elements, the values ​​of these EPD information elements differ. Specifically, in Tables 1c, 1d, and 1e, the value of the EPD information element indicates that the message it belongs to is a 5GMM message. In Table 5, the value of the EPD information element indicates that the message it belongs to is an EPS CIoT data transmission message. In other words, the values ​​of the EPD information elements are the same in Tables 1c, 1d, and 1e, but different from the values ​​in Table 5.

[0432] When the terminal device is in an idle state, this NAS message is used as an EMM message in the service request phase of the EMM process.

[0433] When the terminal device is in a connected state, this NAS message is used as an ESM message in the user data transmission phase of the ESM process.

[0434] Furthermore, when using the NAS protocol to transmit user data, terminal devices and network devices (such as mobility management network elements) need to negotiate NAS protocol capabilities.

[0435] As shown in Table 5, the header of this NAS message is 7 bytes, which saves 11 bytes of overhead compared to the NAS message shown in Table 1a, and 5 bytes of overhead compared to the NAS message shown in Table 1b.

[0436] However, the NAS protocol shown in Table 5 has many drawbacks when transmitting user data, such as:

[0437] First, in the NAS messages shown in Table 5, EPD indicates that the protocol is a brand new NAS protocol, not 4G NAS, but it is used as a 4G NAS protocol, which violates the basic principles of NAS protocols.

[0438] Second, in the idle state, the NAS messages shown in Table 5 are used as EMM messages in the Service Request phase of the EMM process. In other words, using one protocol message within one protocol process violates the fundamental principles of the NAS protocol.

[0439] Third, in connected mode, the NAS messages shown in Table 5 are used as ESM messages in the user data transmission phase of the ESM process. In other words, using one protocol message within one protocol process violates the fundamental principles of the NAS protocol.

[0440] Fourth, the same NAS protocol message, as shown in Table 5, is used as both an EMM message and an ESM message, which violates the basic principles of the NAS protocol.

[0441] In other words, even if a completely new NAS protocol is proposed specifically for transmitting control plane user data, although it can reduce message header overhead to some extent, it violates the basic principles of NAS protocols.

[0442] In S501-S503 of this application, the value of the EPD information cell in the NAS message indicates that the NAS message is a 5GMM message, suitable for the processing flow of 5G communication systems. This can be understood as the NAS message of this application being suitable for control plane user data transmission, but not a new NAS protocol. It is compatible with the processing flow of 5G communication systems and conforms to the basic principles of NAS protocols.

[0443] Similarly, the value of the PD cell in the NAS message indicates that the NAS message is an EMM message, suitable for the processing flow of the 4G communication system. It can be understood that the NAS message in this application is applicable to control plane user data transmission, but it is not a new NAS protocol; it is compatible with the processing flow of the 4G communication system and conforms to the basic principles of the NAS protocol.

[0444] Furthermore, in 4G communication systems, ESM messages and EMM messages are different messages. The security header type information element in the corresponding message header indicates that the NAS message includes user data, thereby reusing the existing security header type information element to reduce message header overhead. It can also avoid the situation where the same message is used as both an EMM message and an ESM message, which is in line with the basic principles of NAS.

[0445] It is understood that, in the above embodiments, the methods and / or steps implemented by the first communication device can also be implemented by components (e.g., processors, chips, chip systems, circuits, logic modules, or software) that can be used in the first communication device; similarly, the methods and / or steps implemented by the second communication device can also be implemented by components (e.g., processors, chips, chip systems, circuits, logic modules, or software) that can be used in the second communication device. The chip system can be composed of chips, or it can include chips and other discrete devices.

[0446] It is understood that, in order to achieve the aforementioned functions, the communication device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0447] This application embodiment can divide the communication device into functional modules according to the above method embodiment. For example, each function can be divided into a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. 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.

[0448] Figure 7 shows a schematic diagram of a communication device 700. The communication device 700 includes a processing module 701 and a transceiver module 702. This communication device 700 can be used to implement the functions of the first or second communication device described above.

[0449] In some embodiments, the communication device 700 further includes a storage module (not shown in FIG. 7) for storing program instructions and data.

[0450] In some embodiments, the transceiver module 702, also referred to as a transceiver unit, is used to implement sending and / or receiving functions. The transceiver module 702 may consist of a transceiver circuit, a transceiver, a transceiver unit, or a communication interface.

[0451] In some embodiments, the transceiver module 702 may include a receiving module and a sending module, respectively configured to perform receiving and sending steps performed by the first communication device (or the second communication device) in the above method embodiments, and / or other processes to support the technology described herein; the processing module 701 may be configured to perform processing steps (e.g., determination) performed by the first communication device (or the second communication device) in the above method embodiments, and / or other processes to support the technology described herein.

[0452] In one possible design, taking the communication device 700 as the first communication device in the above method embodiment as an example:

[0453] Processing module 701 is used to determine the non-access stratum NAS message. The NAS message includes a message header and user data. The message header includes a security header type information element, which indicates that the NAS message is used to transmit user data.

[0454] The transceiver module 702 is used to send NAS messages.

[0455] In one possible design, taking the communication device 700 as the second communication device in the above method embodiment as an example:

[0456] The transceiver module 702 is used to receive non-access stratum (NAS) messages, the NAS messages including a message header and user data, the message header including a security header type information element, the security header type information element indicating that the NAS message is used to transmit the user data.

[0457] Processing module 701 is used to process the user data according to the security header type information element.

[0458] All relevant content of each step involved in the above method embodiments can be referenced from the functional description of the corresponding functional module, and will not be repeated here.

[0459] Optionally, in this application, the transceiver module receiving / sending information can also be understood as the processing module receiving / sending information through the transceiver module. The processing module receiving / sending information through the transceiver module can also be understood as the processing module controlling the transceiver module to receive / send information. Alternatively, the processing module sending information through the transceiver module can be understood as the processing module outputting information to the transceiver module, which then sends that information; the processing module receiving information through the transceiver module can be understood as the transceiver module receiving information and inputting that information into the processing module.

[0460] In this application, the communication device 700 can be presented in an integrated manner by dividing it into various functional modules. Here, "module" can refer to an application-specific integrated circuit (ASIC), a circuit, a processor and memory that executes one or more software or firmware programs, integrated logic circuits, and / or other devices that can provide the above functions.

[0461] In some embodiments, when the communication device 700 in FIG7 is a chip or chip system, the function / implementation process of the transceiver module 702 can be implemented through the input / output interface (or communication interface) of the chip or chip system, and the function / implementation process of the processing module 701 can be implemented through the processor (or processing circuit) of the chip or chip system.

[0462] Since the communication device 700 provided in this embodiment can execute the above method, the technical effects it can achieve can be referred to the above method embodiment, and will not be repeated here.

[0463] As a possible product form, the first or second communication device described in the embodiments of this application can also be implemented using one or more field programmable gate arrays (FPGAs), programmable logic devices (PLDs), controllers, state machines, gate logic, discrete hardware components, any other suitable circuits, or any combination of circuits capable of performing the various functions described throughout this application.

[0464] As another possible product form, the first or second communication device described in this application embodiment can be implemented using a general bus architecture. For ease of explanation, refer to FIG8, which is a schematic diagram of the structure of a communication device 800 provided in an embodiment of this application. The communication device 800 includes a processor 801 and a transceiver 802. The communication device 800 can be a first communication device, or a chip or chip system therein; or, the communication device 800 can be a second communication device, or a chip or module therein. FIG8 only shows the main components of the communication device 800. In addition to the processor 801 and transceiver 802, the communication device 800 may further include a memory 803 and input / output devices (not shown in the figure).

[0465] Optionally, the processor 801 is mainly used to process communication protocols and communication data, control the entire communication device, execute software programs, and process the data of the software programs. The memory 803 is mainly used to store software programs and data. The transceiver 802 may include radio frequency (RF) circuitry and an antenna. The RF circuitry is mainly used for converting baseband signals to RF signals and processing RF signals. The antenna is mainly used for transmitting and receiving RF signals in the form of electromagnetic waves. Input / output devices, such as touch screens, displays, and keyboards, are mainly used to receive user input data and output data to the user.

[0466] Optionally, the processor 801, transceiver 802, and memory 803 can be connected via a communication bus.

[0467] It should be noted that the memory 803 can exist independently of the processor 801, or it can be integrated with the processor 801. The memory 803 can be located inside or outside the communication device 800, without restriction.

[0468] When the communication device is powered on, the processor 801 can read the software program in the memory 803, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor 801 performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency (RF) circuit. The RF circuit processes the baseband signal and transmits the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the communication device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor 801. The processor 801 converts the baseband signal into data and processes the data.

[0469] In another implementation, the radio frequency circuitry and antenna can be set up independently of the processor performing baseband processing. For example, in a distributed scenario, the radio frequency circuitry and antenna can be arranged remotely, independent of the communication device.

[0470] In some embodiments, those skilled in the art will recognize that the above-described communication device 700 can be implemented in the form of the communication device 800 shown in FIG8.

[0471] As an example, the function / implementation process of the processing module 701 in Figure 7 can be implemented by the processor 801 in the communication device 800 shown in Figure 8 calling computer execution instructions stored in the memory 803. The function / implementation process of the transceiver module 702 in Figure 7 can be implemented by the transceiver 802 in the communication device 1000 shown in Figure 8.

[0472] As another possible product form, the first or second communication device in this application may adopt the composition structure shown in FIG. 9, or include the components shown in FIG. 9. FIG. 9 is a schematic diagram of the composition of a communication device 900 provided in this application.

[0473] As shown in Figure 9, the communication device 900 includes at least one processor 901. Optionally, the communication device also includes a communication interface 902.

[0474] When the relevant program instructions are executed in the at least one processor 901, the communication device 900 can implement the methods and any possible designs provided in any of the foregoing embodiments. Alternatively, the processor 901 can implement the methods and any possible designs provided in any of the foregoing embodiments through logic circuits or executable code instructions.

[0475] The communication interface 902 can be used to receive program instructions and transmit them to the processor, or it can be used for the communication device 900 to communicate and interact with other communication devices, such as exchanging control signaling and / or service data. For example, the communication interface 902 can be used to receive signals from other devices besides the communication device 900 and transmit them to the processor 901, or to send signals from the processor 901 to other communication devices besides the communication device 900.

[0476] Optionally, the communication interface 902 can be a code and / or data read / write interface circuit, or the communication interface 902 can be a signal transmission interface circuit between a communication processor and a transceiver, or a chip pin.

[0477] Optionally, the communication device 900 may also include at least one memory 903, which may be used to store the required program instructions and / or data.

[0478] It should be noted that the memory 903 can exist independently of the processor 901, or it can be integrated with the processor 901. The memory 903 can be located inside or outside the communication device 900, without restriction.

[0479] Optionally, the communication device 900 may further include a power supply circuit 904, which can be used to power the processor 901. The power supply circuit 904 may be located in the same chip as the processor 901, or in a separate chip outside the chip containing the processor 901.

[0480] Optionally, the communication device 900 also includes a bus 905, through which the various parts of the communication device 900 can be interconnected.

[0481] In some embodiments, those skilled in the art will recognize that the communication device 700 shown in FIG7 can take the form of the communication device 900 shown in FIG9 in terms of hardware implementation.

[0482] As an example, the function / implementation process of the processing module 701 in Figure 7 can be implemented by the processor 901 in the communication device 900 shown in Figure 9 calling computer execution instructions stored in the memory 903. The function / implementation process of the transceiver module 702 in Figure 7 can be implemented by the communication interface 902 in the communication device 900 shown in Figure 9.

[0483] It should be noted that the structure shown in Figure 9 does not constitute a specific limitation on the first or second communication device. For example, in other embodiments of this application, the first or second communication device may include more or fewer components than shown in the figure, or combine some components, or split some components, or have different component arrangements. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0484] Optionally, the processor in this application can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The general-purpose processor can be a microprocessor, or it can be any conventional processor.

[0485] Optionally, the memory in this application can be volatile memory or non-volatile memory, or it can include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), or direct rambus RAM (DR RAM).

[0486] Optionally, the power supply circuit described in the embodiments of this application includes, but is not limited to, at least one of the following: a power supply line for an electronic system, a power management chip, a power management processor, or a power management control circuit.

[0487] In some embodiments, this application also provides a communication device, which includes a processor for implementing the methods in any of the above method embodiments.

[0488] As one possible implementation, the communication device also includes a memory. This memory stores necessary computer programs and data. The computer program may include instructions, which a processor can invoke to instruct the communication device to execute the methods described in any of the above method embodiments. Alternatively, the memory may not be present in the communication device.

[0489] As another possible implementation, the communication device also includes an interface circuit, which is a code / data read / write interface circuit, used to receive computer execution instructions (which are stored in memory and may be read directly from memory or may be transmitted through other devices) and transmit them to the processor.

[0490] As another possible implementation, the communication device also includes a communication interface for communicating with modules outside the communication device.

[0491] It is understood that the communication device can be a chip or a chip system. When the communication device is a chip system, it can be composed of chips or may include chips and other discrete devices. This application does not specifically limit this.

[0492] This application also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a computer, implements the functions of any of the above-described method embodiments.

[0493] This application also provides a computer program product that, when executed by a computer, implements the functions of any of the above method embodiments.

[0494] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0495] It is understood that the systems, apparatuses, and methods described in this application can also be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms. The units described as separate components may or may not be physically separate, i.e., they may be located in one place or distributed across multiple network units. The components shown as units may or may not be physical units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0496] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. In the above embodiments, they can be implemented entirely or partially by software, hardware, firmware, or any combination thereof. When implemented using a software program, 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, optical fiber, 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 it can contain one or more data storage devices such as servers or data centers that can be integrated with the medium. The available medium may 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 drive (SSD)). In embodiments of this application, the computer may include the aforementioned apparatus. Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, can understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit may implement several functions listed in the claims. Although certain measures are recited in mutually different dependent claims, this does not mean that these measures cannot be combined to produce good results.

Claims

1. A communication method, characterized in that, include: A non-access stratum NAS message is identified, the NAS message including a message header and user data, the message header including a security header type information element, the security header type information element indicating that the NAS message is used to transmit the user data; Send the NAS message.

2. The method according to claim 1, characterized in that, The method is applied to a first communication device; Before determining the NAS message, the method further includes: sending first capability information, the first capability information indicating that the first communication device supports the NAS message.

3. A communication method, characterized in that, include: Receive a non-access stratum NAS message, the NAS message including a message header and user data, the message header including a security header type information element, the security header type information element indicating that the NAS message is used to transmit the user data; The user data is processed according to the security header type information element.

4. The method according to claim 3, characterized in that, Receiving the NAS message includes: receiving the NAS message from the first communication device; Before receiving the NAS message, the method further includes: receiving first capability information from the first communication device, the first capability information indicating that the first communication device supports the NAS message.

5. The method according to claim 2 or 4, characterized in that, The first capability information is included in at least one of the following messages: a registration request message, an attachment request message, or a tracking area update (TAU) request message, wherein the first communication device is a terminal device; or, The first capability information is included in at least one of the following messages: registration acceptance message, attachment acceptance message, or TAU acceptance message, wherein the first communication device is a mobility management network element.

6. The method according to any one of claims 1-5, characterized in that, The security header type information cell also indicates one of the following: The NAS message is securely protected; or, The NAS message is protected for integrity; or... The NAS message is protected by integrity and encrypted; or, The NAS messages are protected for integrity and partially encrypted.

7. The method according to any one of claims 1-6, characterized in that, The structure of the message header is as follows: The value of the EPD cell indicates that the NAS message is a 5GMM (5th Generation Mobile Management) message, and the EPD cell occupies A1 bytes; The first type information indicates the data type of the user data, and the first type information occupies M1 bits; The second type of information indicates the service type of the user data, and the second type of information occupies N1 bits; The secure header type cell occupies P1 bits; M1+N1+P1=8; The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C1 bytes; The SN indicates the sequence number of the NAS message, and the SN occupies D1 bytes; The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q1 bits. The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S1 bits; The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T1 bits; Q1+T1+S1=8; A1, B1, C1, D1, E1, M1, N1, P1, Q1, S1, and T1 are all positive integers.

8. The method according to claim 7, characterized in that, A1 = B1 = D1 = E1 = 1, C1 = 2 or 4; P1 = 4.

9. The method according to any one of claims 1-6, characterized in that, The structure of the message header is as follows: The value of the EPD cell indicates that the NAS message is a 5GMM (5th Generation Mobile Management) message, and the EPD cell occupies A2 bytes; The number of free bits is M2 bits, and the number of secure header type cells occupies P2 bits; M2 + P2 = 8; The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C2 bytes; The SN indicates the sequence number of the NAS message, and the SN occupies D2 bytes; The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q2 bits. The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S2 bits; The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T2 bits; Q2+T2+S2=8; A2, B2, C2, D2, E2, M2, P2, Q2, S2, and T2 are all positive integers.

10. The method according to claim 9, characterized in that, A2 = B2 = D2 = E2 = 1, C2 = 2 or 4; M2 = P2 = 4.

11. The method according to any one of claims 1-6, characterized in that, The structure of the message header is as follows: The value of the EPD cell indicates that the NAS message is a 5GMM (5th Generation Mobile Management) message, and the EPD cell occupies A3 bytes; The first type of information indicates the data type of the user data, and the first type of information occupies M3 bits; The second type of information indicates the service type of the user data, and the second type of information occupies N3 bits; The secure header type cell occupies P3 bits; M3+N3+P3=8; The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C3 bytes; The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q3 bits. The SN indicates the sequence number of the NAS message, and the SN occupies R3 bits; Q3 + R3 = 8; The number of free bits is K3 bits; The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S3 bits; The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T3 bits. A3, B3, C3, D3, E3, M3, N3, P3, R3, K3, S3, and T3 are all positive integers, and Q3 is an integer greater than or equal to 0.

12. The method according to claim 11, characterized in that, A3=B3=D3=E3=1, C3=2 or 4; P3=4.

13. The method according to any one of claims 1-6, characterized in that, The structure of the message header is as follows: The value of the EPD cell indicates that the NAS message is a 5GMM (5th Generation Mobile Management) message, and the EPD cell occupies A4 bytes; The number of free bits is M4 bits; the number of secure header type cells occupies P4 bits; M4 + P4 = 8; The MAC is used for the integrity protection of the NAS messages, and the MAC occupies C4 bytes; The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies Q4 bits; the SN indicates the sequence number of the NAS message, which occupies R4 bits; Q4 + R4 = 8; The second type of information indicates the service type of the user data, and the second type of information occupies K4 bits; The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies S4 bits; The second identifier is used to identify the first session, which is used to transmit the user data. The second identifier occupies T4 bits; K4+S4+T4=8; A4, B4, C4, D4, E4, M4, P4, R4, K4, S4, and T4 are all positive integers, and Q4 is an integer greater than or equal to 0.

14. The method according to claim 13, characterized in that, A4 = B4 = D4 = E4 = 1, C4 = 2 or 4; M4 = P4 = 4.

15. The method according to any one of claims 1-6, characterized in that, The structure of the message header is as follows: The secure header type cell occupies M5 bits; The value of the PD cell indicates that the NAS message is an Evolved Packet System Mobility Management (EMM) message, and the PD cell occupies N5 bits; M5 + N5 = 8; The MAC is used for the integrity protection of the NAS messages, and the MAC occupies 5 bytes. The SN indicates the sequence number of the NAS message, and the SN occupies C5 bytes; The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies P5 bits. The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies Q5 bits; The second identifier is used to identify the first bearer, which is used to transmit the user data. The second identifier occupies S5 bits; P5+Q5+S5=8; A5, B5, C5, D5, M5, N5, P5, Q5, and S5 are all positive integers.

16. The method according to claim 15, characterized in that, A5 = C5 = D5 = 1, B5 = 2 or 4; M5 = N5 = 4.

17. The method according to any one of claims 1-6, characterized in that, The structure of the message header is as follows: The secure header type cell occupies M6 bits; The value of the PD cell indicates that the NAS message is an Evolved Packet System Mobility Management (EMM) message, and the PD cell occupies N6 bits; M6 + N6 = 8; The MAC is used for the integrity protection of the NAS messages, and the MAC occupies 6 bytes. The first identifier is used to identify the security context, which is used for the security protection of the NAS message. The first identifier occupies P6 bits. The SN indicates the sequence number of the NAS message, and the SN occupies K6 bits; P6 + K6 = 8; The second type of information indicates the service type of the user data, and the second type of information occupies R6 bits; The DDX indicates whether downlink data transmission is expected after the user data transmission, and the DDX occupies Q6 bits; The second identifier is used to identify the first bearer, which is used to transmit the user data. The second identifier occupies S6 bits; R6+Q6+S6=8; A6, B6, C6, D6, M6, N6, K6, R6, Q6, and S6 are all positive integers, and P6 is an integer greater than or equal to 0.

18. The method according to claim 17, characterized in that, A6 = C6 = D6 = 1, B6 = 2 or 4; M6 = N6 = 4.

19. The method according to any one of claims 1-18, characterized in that, The message header length is less than or equal to 8 bytes.

20. A communication device, characterized in that, The communication device is a first communication device, including a module for implementing the method as described in any one of claims 1-2 and 5-19.

21. The communication device according to claim 20, characterized in that, The communication device includes terminal equipment, mobility management network elements, or chips.

22. A communication device, characterized in that, The communication device is a second communication device, including a module for implementing the method as described in any one of claims 3-19.

23. The communication device according to claim 22, characterized in that, The communication device includes terminal equipment, mobility management network elements, or chips.

24. A computer-readable storage medium, included in a first communication device, the computer-readable storage medium storing a computer program or instructions, characterized in that, When the computer program or instructions are run, the method as described in any one of claims 1-2 and 5-19 is implemented.

25. A computer program product, said computer program product being included in a first communication device, characterized in that, When the computer program product is run, the method as described in any one of claims 1-2 and 5-19 is implemented.

26. A computer-readable storage medium, included in a second communication device, the computer-readable storage medium storing a computer program or instructions, characterized in that, When the computer program or instructions are run, the method as described in any one of claims 3-19 is implemented.

27. A computer program product, said computer program product being included in a second communication device, characterized in that, When the computer program product is run, the method as described in any one of claims 3-19 is implemented.

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