A data transmission control method, system and related device in a satellite communication system

Abstract

A data transmission control method, system, and related apparatus in a satellite communication system. In this method, a terminal can split an MDCP SDU at the MDCP layer into one or more fixed-length MDCP segmented data, and add a successor indication field to the header of each MDCP segmented data to obtain an MDCP PDU. The successor indication field can be used to indicate whether the current MDCP PDU is the starting frame, intermediate frame, or last frame of continuously transmitted frames, or is a frame transmitted separately. The terminal can send one or more MDCP PDUs to a Beidou network device. The Beidou network device can combine multiple MDCP PDUs into one MDCP SDU based on the successor indication field in the MDCP PDU. By implementing this method, the terminal can also reliably transmit data to the Beidou network device under the constraints of the Beidou communication system and rate limitations.

Description

Technical Field

[0001] The present application relates to the field of satellite communications, and in particular to a data transmission control method, system and related devices in a satellite communication system. Background Art

[0002] The Beidou satellite navigation system is a major infrastructure integrating positioning, timing, and communications. The Beidou short message communication service is one of the key features that distinguishes the Beidou satellite navigation system from other global navigation systems, such as the US GPS, Russia's GLONASS, and Europe's GALILEO. It is particularly suitable for communication in areas such as oceans, deserts, grasslands, and uninhabited areas where mobile communications are not available, cannot be reached, or where communications systems are disrupted. The Beidou-3 satellite's short message system has upgraded the short message technology architecture. To address the specific characteristics of civilian services and equipment, a communication protocol must be designed based on the Beidou short message system.

[0003] Because the BeiDou short message service (BDS) communication system operates via satellite links, its key characteristics are: 1. Long latency; 2. High link loss; 3. Support for primarily bursty short message services; and 4. No support for link state management, mobility management, or broadcast control information. Current wireless communication protocols are not suitable for BDS communication systems. This is because, due to the long transmission distances of satellite communications, BDS communication systems require high terminal transmit power. Furthermore, the limited radio frequency capabilities of civilian terminals result in inbound data rates far lower than those of dedicated terminals. Therefore, a specific data transmission process needs to be designed to reduce signaling overhead and ineffective transmission within the constraints of the BeiDou communication system and its limited rate, thereby achieving reliable and orderly data transmission. Summary of the Invention

[0004] The present application provides a data transmission control method, system and related devices in a satellite communication system. Through the method provided by the present application, under the constraints of the Beidou communication system and rate limitation, the terminal can reduce signaling overhead and reduce invalid transmission, thereby achieving reliable and orderly data transmission.

[0005] In a first aspect, the present application provides a data transmission control method in a satellite communication system, which may include: after the terminal adds padding data and a redundant length indication field to the first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, it is divided into M data convergence layer protocol data units MDCP PDU, where M is a positive integer; wherein the redundant length indication field is used to indicate the data length of the padding data, the M MDCP PDUs include the first MDCP PDU, the header information of the first MDCP PDU includes a subsequent indication field, and the subsequent indication field is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; the terminal sends the first MDCP PDU to the Beidou network device.

[0006] In this way, under the constraints of the Beidou communication system and rate limitations, the terminal can also reliably transmit data to Beidou network equipment.

[0007] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0008] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0009] In this way, the terminal segments the data packet at the MDCP layer, enabling efficient data transmission within the constraints of the Beidou communication system and rate limits. The MDCP PDU header includes a Subsequent Indicator field, which indicates the order of the first MDCP PDU within the M MDCP PDUs. The receiving device can use this field to determine whether the received MDCP PDU is erroneous. This reduces signaling overhead and ineffective transmissions.

[0010] In a possible implementation, after adding padding data and a redundant length indication field to a first message data convergence layer service data unit (MDCP SDU) at a message data convergence layer (MDCP) layer, the terminal divides the first message data convergence layer service data unit (MDCP SDU) into M data convergence layer protocol data units (MDCP PDUs). Specifically, the terminal generates an application layer message at an application layer; and the terminal uses the application layer message as a first MDCP SDU at the MDCP layer, and after adding padding data and a redundant length indication field to the first MDCP SDU, divides the first MDCP SDU into M MDCP PDUs.

[0011] In one possible implementation, the terminal uses the application layer message as a first MDCP SDU at the MDCP layer, and after adding padding data and a redundant length indicator field to the first MDCP SDU and before dividing it into M MDCP PDUs, the method further includes: the terminal obtaining original data; the terminal compressing the original data at the application layer to obtain compressed data; the terminal encrypting the compressed data at the application layer to obtain encrypted data; the terminal adding message header information to a header of the encrypted data to obtain an application layer message; wherein the message header information includes a compression indicator field and an encryption indicator field, the compression indicator field being used to indicate a compression algorithm used when compressing the original data, and the encryption indicator field being used to indicate an encryption algorithm used when encrypting the compressed data.

[0012] In one possible implementation, the terminal sends the first MDCP PDU to the Beidou network device, specifically including: the terminal transmits the first MDCP PDU to the satellite link control SLC layer as the first satellite link control layer service data unit SLC SDU of the SLC layer; the terminal divides the first SLC SDU into N satellite link control layer protocol data units SLC PDU at the SLC layer, where N is a positive integer; wherein the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a service data unit alternation indication SAI field, a total number of frames field, and a frame sequence number field; the SAI field is used to indicate whether the first SLC PDU is retransmitted data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU; the terminal sends the first SLC PDU to the Beidou network device.

[0013] In this way, by flipping the value of the SAI field of the SLC PDU, it is indicated whether the SLC PDU is retransmitted data, which can ensure that the Beidou network device can identify whether the received SLC PDU is retransmitted data, thereby ensuring continuous data transmission in the Beidou communication system.

[0014] In one possible implementation, the terminal sends the first SLC PDU to the Beidou network device, specifically including: the terminal sends the first SLC PDU from the SLC layer to the physical PHY layer as the first coding block of the PHY layer; the terminal adds check bit information at the end of the first coding block at the PHY layer, and encodes the first coding block and the check bit information to obtain first coded data; the terminal inserts pilot information into the first coded data at the PHY layer to obtain first pilot data; the terminal modulates the first pilot data and the synchronization header of the first pilot data at the PHY layer to obtain first modulated data and a first modulation synchronization header; the terminal spreads the first modulated data and the modulation synchronization header at the PHY layer to obtain first spread spectrum modulated data; the terminal sends the first spread spectrum modulated data as the first physical frame to the Beidou network device at the PHY layer.

[0015] In a possible implementation, the terminal determines the data length of the first MDCP PDU according to the data length of the first MDCP SDU and the data length of the first physical frame.

[0016] In this way, the terminal can know how to split the MDCP SDU into multiple MDCP PDUs.

[0017] In a second aspect, a data transmission control method in a satellite communication system is provided, which may include: a Beidou network device receives M data convergence layer protocol data units (MDCP PDUs) sent by a terminal, where M is a positive integer; wherein the M MDCP PDUs include a first MDCP PDU, and the header information of the first MDCP PDU includes a successor indication field, which is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; and the Beidou network device splices the M MDCP PDUs into a first message data convergence layer service data unit (MDCP SDU) at the message data convergence MDCP layer.

[0018] In this way, data can be reliably transmitted between Beidou network devices and terminals under the constraints of the Beidou communication system and rate limitations.

[0019] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0020] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0021] In this way, the Beidou network device can accurately splice multiple MDCP PDUs into an MDCP SDU according to the order of the MDCP PDU in multiple MDCP PDUs indicated by the subsequent indication field in the MDCP PDU.

[0022] In a possible implementation, the Beidou network device splices the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: when the second MDCP PDU received by the Beidou network device subsequently indicates that the second MDCP PDU is the last one of the M MDCP PDUs, the Beidou network device splices the M MDCP PDUs into a first MDCP SDU at the MDCP layer, and reports the first MDCP SDU as an application layer message from the MDCP layer to the application layer.

[0023] In one possible implementation, the application layer message includes message header information and encrypted data, the message header information includes an encryption indication field and a compression indication field, the compression indication field is used to indicate the compression algorithm used by the terminal when compressing the original data into compressed data, and the encryption indication field is used to indicate the encryption algorithm used by the terminal when encrypting the compressed data into encrypted data; the method also includes: the Beidou network device decrypts the encrypted data in the application layer message at the application layer through the encryption algorithm indicated by the encryption indication field in the application layer message to obtain compressed data; the Beidou network device decompresses the compressed data at the application layer through the compression algorithm indicated by the compression indication field in the application layer message to obtain the original data.

[0024] In one possible implementation, it also includes: the Beidou network device splices N SLC PDUs into a first SLC SDU at the SLC layer, and reports the first SLC SDU as the first MDCP PDU from the SLC layer of the Beidou network device to the MDCP layer of the Beidou network device; wherein, the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a service data unit alternating indication SAI field, a total number of frames field, and a frame sequence number field; the SAI field is used to indicate whether the first SLC PDU is retransmitted data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU.

[0025] In one possible implementation, the Beidou network device splices N SLC PDUs into a first SLC SDU at the SLC layer, and reports the first SLC SDU as a first MDCP PDU from the SLC layer of the Beidou network device to the MDCP layer of the Beidou network device. The method also includes: the Beidou network device obtains the first spread spectrum modulation data sent by the terminal at the PHY layer; the Beidou network device despreads the first spread spectrum modulation data at the PHY layer to obtain the first modulation data and the first modulation synchronization header; the Beidou network device demodulates the first modulation data and the first modulation synchronization header at the PHY layer to obtain the first pilot data and the first synchronization header; the Beidou network device removes the pilot information in the first pilot data at the PHY layer to obtain the first coded data; the Beidou network device decodes the first coded data at the PHY layer to obtain the first coded block and the first verification information; the Beidou network device verifies the first coded block based on the first verification information at the PHY layer, and after the verification is successful, uses the first coded block as the first SLC in the first SLC SDU in the SLC layer of the Beidou network device. The PDU is presented from the PHY layer to the SLC layer of the Beidou network device.

[0026] In one possible implementation, the Beidou network device splices M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: after the Beidou network device removes the successor indication field of each MDCP PDU in the M MDCP PDUs at the MDCP layer, the M MDCP PDUs are spliced ​​into a first MDCP SDU in the order indicated by the successor indication of each MDCP PDU in the M MDCP PDUs.

[0027] According to a third aspect, a data transmission control method in a satellite communication system is provided, which may include: a Beidou network device divides a first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDUs at a message data convergence MDCP layer, where M is a positive integer; wherein the M MDCP PDUs include a first MDCP PDU, and the header information of the first MDCP PDU includes a successor indication field, which is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; and the Beidou network device sends the first MDCP PDU.

[0028] In this way, data can be reliably transmitted between Beidou network devices and terminals under the constraints of the Beidou communication system and rate limitations.

[0029] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0030] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0031] In this way, Beidou network devices segment data packets at the MDCP layer, enabling efficient data transmission within the constraints of the Beidou communication system and its limited rate. The MDCP PDU header includes a Subsequent Indicator field, which indicates the order of the first MDCP PDU within M MDCP PDUs. The receiving device can use this field to determine whether the received MDCP PDU is erroneous. This reduces signaling overhead and ineffective transmissions.

[0032] In one possible implementation, the Beidou network device divides the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDU at the message data convergence MDCP layer, specifically including: the Beidou network device generates an application layer message at the application layer; the Beidou network device uses the application layer message as the first MDCP SDU at the MDCP layer, and divides the first MDCP SDU into M MDCP PDUs.

[0033] In one possible implementation, the Beidou network device generates an application layer message at the application layer, specifically including: the Beidou network device obtains original data; the Beidou network device compresses the original data at the application layer to obtain compressed data; the Beidou network device encrypts the compressed data at the application layer to obtain encrypted data; the Beidou network device adds message header information to the encrypted data header to obtain an application layer message; wherein the message header information includes a compression indication field and an encryption indication field, the compression indication field is used to indicate the compression algorithm used when compressing the original data, and the encryption indication field is used to indicate the encryption algorithm used when encrypting the compressed data.

[0034] In a possible implementation, the Beidou network device sends the first MDCP PDU, specifically including: the Beidou network device transmits the first MDCP PDU to the satellite link control SLC layer as the first satellite link control layer service data unit SLC SDU of the SLC layer; the Beidou network device divides the first SLC SDU into N satellite link control layer protocol data units SLC PDUs at the SLC layer, where N is a positive integer; wherein the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a first user ID field and a first frame type field, the first user ID field is used to indicate the terminal receiving the first user frame, and the first frame type field is used to indicate the frame type of the first user frame; the Beidou network device sends the first SLC PDU.

[0035] In one possible implementation, the Beidou network device sends a first physical frame and a second physical frame, including: the Beidou network device adds first check bit information at the end of the first physical frame at the PHY layer, encodes the first physical frame and the first check bit information to obtain first coded data, adds second check bit information at the end of the second physical frame, and encodes the second physical frame and the second check bit information to obtain second coded data; the Beidou network device modulates the first coded data and the first reserved field of the first coded data at the PHY layer to obtain first modulated data, and modulates the second coded data and the second reserved field of the second coded data to obtain second modulated data; the Beidou network device spreads the first modulated data at the PHY layer to obtain first spread spectrum modulated data, and spreads the second modulated data to obtain second spread spectrum modulated data; the Beidou network device sends the first spread spectrum modulated data and the first pilot information of the first spread spectrum modulated data, as well as the second spread spectrum modulated data and the second pilot information of the second spread spectrum modulated data at the PHY layer.

[0036] In a possible implementation, the method further includes: the Beidou network device determining the data length of the first MDCP PDU according to the data length of the first MDCP SDU and the data length of the first physical frame.

[0037] In this way, the Beidou network device can know how to split the MDCP SDU into multiple MDCP PDUs.

[0038] In a fourth aspect, a data transmission control method in a satellite communication system is provided, which may include: a terminal receives M data convergence layer protocol data units (MDCP PDUs) sent by a Beidou network device, where M is a positive integer; wherein the M MDCP PDUs include a first MDCP PDU, and the header information of the first MDCP PDU includes a successor indication field, which is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; and the terminal splices the M MDCP PDUs into a first message data convergence layer service data unit (MDCP SDU) at the message data convergence MDCP layer.

[0039] In this way, data can be reliably transmitted between Beidou network devices and terminals under the constraints of the Beidou communication system and rate limitations.

[0040] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0041] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0042] In this way, the terminal can accurately splice multiple MDCP PDUs into an MDCP SDU according to the order of the MDCP PDU in multiple MDCP PDUs indicated by the subsequent indication field in the MDCP PDU.

[0043] In a possible implementation, the terminal splices M MDCP PDUs into a first message data convergence layer service data unit (MDCP SDU) at a message data convergence layer (MDCP layer), including: when a second MDCP PDU received by the terminal subsequently indicates that the second MDCP PDU is the last one of the M MDCP PDUs, the terminal splices the M MDCP PDUs into a first MDCP SDU at the MDCP layer, and reports the first MDCP SDU from the MDCP layer to the application layer as an application layer message.

[0044] In one possible implementation, the application layer message includes message header information and encrypted data, the message header information includes an encryption indication field and a compression indication field, the compression indication field is used to indicate the compression algorithm used by the terminal when compressing the original data into compressed data, and the encryption indication field is used to indicate the encryption algorithm used by the terminal when encrypting the compressed data into encrypted data; the method also includes: the terminal decrypts the encrypted data in the application layer message at the application layer using the encryption algorithm indicated by the encryption indication field in the application layer message to obtain compressed data; the terminal decompresses the compressed data at the application layer using the compression algorithm indicated by the compression indication field in the application layer message to obtain the original data.

[0045] In a possible implementation, the method may also include: the Beidou network device splices N SLC PDUs into a first SLC SDU at the SLC layer, and reports the first SLC SDU as the first MDCP PDU from the SLC layer of the Beidou network device to the MDCP layer of the Beidou network device; wherein, the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a first user ID field and a first frame type field, the first user ID field is used to indicate the terminal receiving the first user frame, and the first frame type field is used to indicate the frame type of the first user frame.

[0046] In one possible implementation, before the terminal splices N SLC PDUs into a first SLC SDU at the SLC layer and reports the first SLC SDU as a first MDCP PDU from the SLC layer of the Beidou network device to the MDCP layer of the Beidou network device, the method may further include: the terminal obtains first spread spectrum modulation data sent by the terminal at the PHY layer; the terminal despreads the first spread spectrum modulation data at the PHY layer to obtain first modulation data and a first modulation synchronization header; the terminal demodulates the first modulation data and the first modulation synchronization header at the PHY layer to obtain first pilot data and a first synchronization header; the terminal removes pilot information from the first pilot data at the PHY layer to obtain first coded data; the Beidou network device decodes the first coded data at the PHY layer to obtain a first coded block physical frame and first verification information; the terminal verifies the first coded block based on the first verification information at the PHY layer, and after the verification is successful, presents the first user frame in the first coded block whose ID field is the same as the terminal ID as the first SLC PDU in the first SLC SDU in the SLC layer of the terminal from the PHY layer to the SLC layer of the terminal.

[0047] In one possible implementation, the terminal, at a message data convergence MDCP layer, splices M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU, including: after the terminal, at the MDCP layer, removes a successor indication field of each MDCP PDU in the M MDCP PDUs, splicing the M MDCP PDUs into the first MDCP SDU in an order indicated by the successor indication of each MDCP PDU in the M MDCP PDUs.

[0048] In the fifth aspect, a Beidou communication system is provided, which may include Beidou network equipment and terminals; wherein the terminal can be used to execute the method in any possible implementation of the above-mentioned first aspect and fourth aspect; the Beidou network equipment can be used to execute the method in any possible implementation of the above-mentioned second aspect and third aspect.

[0049] In a sixth aspect, the present application provides a communication device comprising one or more processors, one or more memories, and a transceiver. The transceiver and the one or more memories are coupled to the one or more processors, the one or more memories being configured to store computer program code, the computer program code comprising computer instructions. When the one or more processors execute the computer instructions, the communication device performs the method of any possible implementation of the first and fourth aspects.

[0050] The communication device may be a terminal or other product-type equipment.

[0051] In a seventh aspect, the present application provides a communication device comprising one or more processors, one or more memories, and a transceiver. The transceiver and the one or more memories are coupled to the one or more processors, the one or more memories being configured to store computer program code, the computer program code comprising computer instructions. When the one or more processors execute the computer instructions, the communication device performs the method of any possible implementation of the second and third aspects described above.

[0052] The communication device may be a Beidou network device, or any network element or a combination of multiple network elements in the Beidou network device.

[0053] In an eighth aspect, the present application provides a computer storage medium comprising computer instructions, which, when executed on a computer, enable the computer to execute a method in any possible implementation of the second and third aspects above.

[0054] In a ninth aspect, the present application provides a computer storage medium comprising computer instructions, which, when executed on a computer, enable the computer to execute a method in any possible implementation of the first and fourth aspects above.

[0055] In a tenth aspect, the present application provides a computer program product, which, when executed on a computer, enables the computer to execute the method in any possible implementation of the second and third aspects above.

[0056] In an eleventh aspect, the present application provides a computer program product, which, when executed on a computer, enables the computer to execute the method in any possible implementation of the first and fourth aspects above.

[0057] In the twelfth aspect, the present application provides a chip or chip system, which is applied to a terminal, including a processing circuit and an interface circuit, the interface circuit is used to receive code instructions and transmit them to the processing circuit, and the processing circuit is used to run the code instructions to execute the method in any possible implementation of the above-mentioned first and fourth aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 1 is a schematic diagram of the architecture of a Beidou communication system 10 provided in an embodiment of the present application;

[0059] Figure 2 This is a schematic diagram of the data inbound transmission process in a Beidou communication system provided by an embodiment of the present application;

[0060] Figure 3 1 is a schematic diagram of a protocol encapsulation architecture for inbound data of a Beidou communication system 10 provided in an embodiment of the present application;

[0061] Figure 4 1 is a schematic diagram of a protocol parsing architecture for inbound data of a Beidou communication system 10 provided in an embodiment of the present application;

[0062] Figure 5 This is a schematic diagram of a scenario in which multiple MDCP PDUs are successfully transmitted according to an embodiment of the present application;

[0063] Figure 6 This is a schematic diagram of a scenario in which a single MDCP PDU is successfully transmitted, provided by an embodiment of the present application;

[0064] Figure 7 This is a schematic diagram of a scenario in which multiple MDCP PDU transmissions fail, as provided in an embodiment of the present application;

[0065] Figure 8 This is a schematic diagram of a scenario in which multiple MDCP PDU transmissions fail, as provided in an embodiment of the present application;

[0066] Figure 9 This is a schematic diagram of a scenario in which multiple MDCP PDUs are successfully transmitted according to an embodiment of the present application;

[0067] Figure 10 1 is a schematic diagram of the protocol processing flow of data at the MDCP layer and the SLC layer of the Beidou communication system 10 provided in an embodiment of the present application;

[0068] Figure 11A 1 is a schematic diagram of a protocol encapsulation architecture for outbound data of a Beidou communication system 10 provided in an embodiment of the present application;

[0069] Figure 11B 1 is a schematic diagram of a protocol parsing architecture for outbound data of a Beidou communication system 10 provided in an embodiment of the present application;

[0070] Figure 11C A flowchart of a data transmission control method in a satellite communication system provided in an embodiment of the present application;

[0071] Figure 11D A schematic flow chart of a data transmission control method in a satellite communication system provided in an embodiment of the present application;

[0072] Figure 12 is a schematic structural diagram of an electronic device provided in an embodiment of the present application;

[0073] Figure 13 A schematic structural diagram of a communication device provided in an embodiment of the present application;

[0074] Figure 14 A schematic structural diagram of another communication device provided in an embodiment of the present application;

[0075] Figure 15 A schematic structural diagram of another communication device provided in an embodiment of the present application;

[0076] Figure 16 A schematic diagram of the structure of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0077] The terms used in the following examples of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. As used in the specification and appended claims of the present application, the singular expressions "a," "an," "said," "above," "the," and "this" are intended to include plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in the present application refers to and encompasses any or all possible combinations of one or more of the listed items.

[0078] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.

[0079] The following introduces a Beidou communication system 10 provided in an embodiment of the present application.

[0080] Figure 1 A schematic diagram of the architecture of a Beidou communication system 10 provided in an embodiment of the present application is shown.

[0081] As above Figure 1 As shown, the Beidou communication system 10 may include a terminal 100, a Beidou short message satellite 21, a Beidou network device 200, a short message center 25, and a terminal 300. Optionally, the Beidou communication system 10 may further include a national emergency rescue platform 26 and a national emergency rescue center 27.

[0082] Terminal 100 can send short messages to BeiDou short message satellites 21. BeiDou short message satellites 21 only relay the short messages sent by terminal 100 and directly forward them to BeiDou network devices 200 on the ground. BeiDou network devices 200 can parse the short messages forwarded by the satellites according to the BeiDou communication protocol and forward the general message content parsed from the short messages to a short message service center (SMSC) 25. The SMSC 25 can forward the message content to terminal 300 via a traditional cellular communication network. BeiDou network devices 200 can also transmit emergency messages sent by terminal 100 to the National Emergency Rescue Center 27 via the National Emergency Rescue Platform 26.

[0083] The terminal 300 can also send a short message to the short message center 25 through a traditional cellular communication network. The short message center 25 can forward the short message of the terminal 300 to the Beidou network device 200. The Beidou network device 200 can relay the short message of the terminal 300 to the terminal 100 via the Beidou short message satellite 21.

[0084] Among them, the above-mentioned Beidou network equipment 200 may include a Beidou ground transceiver station 22, a Beidou central station 23 and a Beidou short message fusion communication platform 24. Among them, the Beidou ground transceiver station 22 may include one or more devices with a sending function and one or more devices with a receiving function, or may include one or more devices with a sending function and a receiving function, which is not limited here. The Beidou ground transceiver station 22 can be used for the Beidou network equipment 200 to process data at the physical layer (physical layer protocol, PHY). The Beidou central station 23 can be used for the Beidou network equipment 200 to process data at the satellite link layer (satellite link control protocol, SLC) layer and the message convergence layer (message data convergence protocol, MDCP). The Beidou short message fusion communication platform 24 can be used for the data processing function at the application layer (application layer protocol, APP).

[0085] Because the BeiDou communication system 10 communicates via satellite links, its main characteristics are long latency (approximately 270ms one-way) and high link loss. Currently, the BeiDou communication system 10 primarily supports short message bursts and does not support link state management, mobility management, or broadcast control information.

[0086] The terminal 100 can actively send data to the Beidou network device 200 via the Beidou short message satellite 21. However, due to the lack of air interface signaling, the ground central station cannot actively page the user. Due to the long transmission distance of satellite communication, the Beidou communication system 10 requires high transmission power for the terminal 100. Due to the limitations of the radio frequency components on the current terminal 100, the terminal 100 cannot continuously send signals to the Beidou short message satellite 21 for a long time. In order to minimize damage to the radio frequency components on the terminal 100, the radio frequency components of the terminal 100 must stop working for a period of time after being in the sending state for a period of time before switching to the sending state to continue working. The duration of the sending state on the terminal 100 is determined by the underlying hardware capabilities of the terminal 100. In the above-mentioned Beidou communication system 10, in order to ensure that the data received and sent by the terminal 100 do not interfere with each other, the terminal 100 does not support sending and receiving data at the same time. The terminal 100 needs to wait for receiving data sent by the Beidou network device 200 after sending data.

[0087] The working mode of the Beidou network device 200 may be a duplex mode, in which data can be sent and received simultaneously, and the Beidou network device 200 may send and receive data for a long time.

[0088] The average consumer's usage habits may lead to the sending of a large amount of data at once. When this amount of data is large, the terminal must transmit it as multiple frames, which takes a long time. To avoid ineffective transmission, a separate layer protocol is needed to manage the multiple frames sent by the user. Therefore, the Message Data Convergence Protocol (MDCP) was defined. This MDCP layer receives application layer data passed down from the application layer and sends the processed data packets to the underlying Satellite Link Control Protocol (SLC).

[0089] Based on the MDCP layer, an embodiment of the present application provides a data transmission control method in a satellite communication system. The terminal 100 can use the application layer message as an MDCP SDU of the MDCP layer. The terminal 100 can add padding data (padding) to the end of an MDCP SDU of the MDCP layer to a specified length, and add a redundant length indication field to the end of the padding data field or the header of the MDCP SDU. The redundant length indication field can be used to indicate the length of the padding data. The terminal 100 can split the MDCP SDU after the redundant data is padded and the redundant length indication field is added into one or more fixed-length MDCP segment data (M_segement), and add a subsequent indication field to the header of each MDCP segment data to obtain an MDCP PDU, that is, the MDCP PDU includes an M_segement and a subsequent indication field. The subsequent indication field can be used to indicate whether the current MDCP PDU is the starting frame, an intermediate frame, or the last frame of continuously transmitted frames; or a frame transmitted separately. The terminal 100 can send one or more MDCP PDUs to the Beidou network device 200. The Beidou network device 200 may combine multiple MDCP PDUs into one MDCP SDU according to the subsequent indication field in the MDCP PDU.

[0090] In this way, under the constraints of the Beidou communication system and rate limitations, the terminal 100 can also send data to the Beidou network device 200.

[0091] In the embodiment of the present application, the scenario in which the terminal 100 sends data to the Beidou network device 200 is defined as inbound, and the scenario in which the Beidou network device 200 sends data to the terminal 100 is defined as outbound.

[0092] Figure 2 The present invention shows a data inbound transmission process in a Beidou communication system provided by an embodiment of the present application.

[0093] like Figure 2As shown, data inbound may refer to the terminal 100 sending data to the Beidou network device 200. For example, the terminal 100 may send a data frame to the Beidou ground transceiver station 22. The Beidou ground transceiver station 22 may send the data frame to the Beidou central station 23. The Beidou central station 23 may aggregate the data frames into a data message and report it to the Beidou short message fusion communication platform 24. After receiving the data frame sent by the terminal 100, the Beidou central station 23 may return an SLC layer acknowledgment character (ACK) to the terminal 100. The ACK may be used to indicate whether the Beidou network device 200 has successfully received the data frame sent by the terminal 100.

[0094] The following describes a protocol encapsulation architecture for inbound data of a Beidou communication system 10 provided in an embodiment of the present application.

[0095] Figure 3 A schematic diagram of a protocol encapsulation architecture for inbound data of a Beidou communication system 10 provided in an embodiment of the present application is shown.

[0096] like Figure 3 As shown, the Beidou message transmission protocol layer on the terminal 100 can be divided into an application layer (application layer protocol), a message data convergence protocol (MDCP), a satellite link layer (satellite link control protocol, SLC) and a physical layer (physical layer protocol, PHY).

[0097] When the terminal 100 sends data to the BeiDou network device 200, the workflow of the BeiDou message transmission protocol on the terminal 100 may be as follows:

[0098] At the APP layer, terminal 100 can compress the original data into compressed data using a compression algorithm and add a compression indicator field to the front of the compressed data. The compression indicator field can be used to indicate the compression algorithm type used for the compressed data. Terminal 100 can then encrypt the compressed data to obtain encrypted data and add an encryption algorithm field to the header of the encrypted data. The encryption algorithm field is used to indicate the encryption algorithm type used for the encrypted data. Terminal 100 can encapsulate the encrypted data, the compression indicator field, and the encryption indicator field into an application layer message and send it to the MDCP layer. The application layer message includes a message header and message data. The message header includes, among other things, a compression indicator field and an encryption indicator field. The message data includes the encrypted data.

[0099] Optionally, the terminal 100 may also encrypt the compression indication field and the compressed data together to obtain encrypted data.

[0100] At the MDCP layer, the terminal 100 can obtain the application layer message sent by the APP layer through the inter-layer interface and use the application layer message as an MDCP SDU. At the MDCP layer, the terminal 100 can add padding data (padding) to the end of the MDCP SDU to a specified length and add a redundant length indication field to the header of the MDCP SDU. The redundant length indication field can be used to indicate the length of the padding data. The terminal 100 can split the padding data and the MDCP SDU after adding the redundant length indication field into one or more fixed-length MDCP segment data (M_segement), and add a subsequent indication field to the header of each MDCP segment data to obtain an MDCP PDU, that is, the MDCP PDU includes an M_segement and a subsequent indication field. The subsequent indication field can be used to indicate whether the current MDCP PDU is the starting MDCP PDU, an intermediate MDCP PDU, or the last MDCP PDU of multiple MDCP PDUs sent continuously; or a single MDCP PDU sent separately.

[0101] At the SLC layer, terminal 100 can obtain the MDCP PDU sent by the MDCP layer through the inter-layer interface as an SLC SDU. At the SLC layer, terminal 100 can segment the SLC SDU into one or more (up to four) fixed-length SLC segments (S_segements) and add frame header information to the header of each S_segement to obtain an SLC PDU. The frame header information includes the service data unit alternated indicator (SAI) field, the total number of frames field, and the frame sequence number field.

[0102] The SAI field may be used to indicate whether the SLC PDU belongs to an unsent SLC SDU.

[0103] The total number of frames field may be used to indicate the total number of SLC PDUs included in the SLC SDU to which the SLC PDU belongs.

[0104] The frame sequence number field can be used to indicate the sequence number of the SLC PDU in the SLC SDU to which it belongs.

[0105] At the PHY layer, the terminal 100 can obtain the SLC PDU sent by the SLC layer through the inter-layer interface as the code block of the PHY layer, and add a synchronization header to the head of the code block and a check bit field to the tail of the code block. In the above-mentioned Beidou communication system 10, a cyclic redundancy check (CRC) can be used to check the code block, so the check bit field can include a CRC code. The terminal 100 can encode the code block and the check bit field (for example, polar coding) to obtain coded data, and then insert a pilot into the coded data to obtain pilot coded data (pilot+data). Then, the terminal 100 modulates the synchronization header and pilot coded data in sequence through the underlying hardware to obtain modulated data. The terminal 100 can spread the modulated data to obtain spread spectrum modulated data (spread+modulated data). The terminal 100 can send the spread spectrum modulated data to the Beidou short message satellite 21, which is relayed to the Beidou network device 200 via the Beidou short message satellite 21.

[0106] The following describes a protocol parsing architecture for inbound data of a Beidou communication system 10 provided in an embodiment of the present application.

[0107] Figure 4 A schematic diagram of a protocol parsing architecture for inbound data of a Beidou communication system 10 provided in an embodiment of the present application is shown.

[0108] like Figure 4 As shown, the BeiDou short message transmission protocol layer of the BeiDou network device 200 can be divided into an application layer protocol, a message data convergence protocol (MDCP), a satellite link control protocol (SLC), and a physical layer protocol (PHY). The BeiDou network device 200 can include a BeiDou ground transceiver station 22, a BeiDou central station 23, and a BeiDou short message fusion communication platform 24. The BeiDou ground transceiver station 22 can be used to be responsible for protocol processing at the PHY layer. The BeiDou central station 23 can be used to be responsible for protocol processing at the SLC layer and the MDCP layer. The BeiDou short message fusion communication platform 24 can be used to be responsible for protocol processing at the APP layer.

[0109] When the BeiDou network device 200 receives data sent by the terminal 100, the workflow of the BeiDou short message transmission protocol layer of the BeiDou network device 200 may be as follows:

[0110] At the PHY layer, the Beidou network device 200 can obtain the pilot coded data after modulation and spread spectrum sent by the terminal 100. The Beidou network device 200 can despread the received spread spectrum modulated data (spread+modulated data) to obtain modulated data (modulated data). Then, the Beidou network device 200 can demodulate the modulated data to obtain pilot coded data (pilot+data). Next, the Beidou network device 200 removes the pilot information in the pilot coded data to obtain coded data (code data). Then, the Beidou network device 200 can decode the coded data and verify the integrity of the coded block (code block) through the check data in the check bit field. If complete, the Beidou network device 200 can extract the coded block (code block) and present it to the SLC layer through the inter-layer interface as the SLC PDU of the SLC layer.

[0111] At the SLC layer, the BeiDou network device 200 can concatenate SLC PDUs belonging to the same SLC SDU into one SLC SDU based on the frame header information of the SLC PDU. The BeiDou network device 200 can present the SLC SDU to the MDCP layer through the inter-layer interface as an MDCP PDU of the MDCP layer.

[0112] At the MDCP layer, the BeiDou network device 200 can concatenate all MDCP PDUs belonging to the same MDCP SDU into one MDCP SDU. The BeiDou network device 200 can present the MDCP SDU to the APP layer through the inter-layer interface as an application layer message received by the APP layer.

[0113] At the APP layer, the Beidou network device 200 can decrypt and decompress the application layer message based on the message header of the application layer message to obtain the original data.

[0114] In the embodiments of the present application, the above-mentioned protocol processing process is only an example, and the present application does not limit the specific operations of the protocol processing.

[0115] Next, the fields involved in the MDCP SDU and MDCP PDU in the MDCP layer are introduced in detail.

[0116] 1. Redundant length indication field in MDCP SDU

[0117] The Redundancy Length Indication field is used to indicate the length of the padding in the MDCP SDU. In one possible implementation, the length of the Redundancy Length Indication field is 8 bits. It is understood that the embodiment of the present application does not limit the length of the Redundancy Length Indication field.

[0118] 2. Subsequent indication field in MDCP PDU

[0119] The data length of the subsequent indication field may be 2 bits. In one possible implementation, the value and corresponding meaning of the subsequent indication field may be as shown in Table 1 below.

[0120] Table 1

[0121] Subsequent instructions illustrate 00 A single MDCP PDU 01 The first PDU among multiple MDCP PDUs 11 The middle PDU among multiple MDCP PDUs 10 The last PDU in multiple MDCP PDUs

[0122] As shown in Table 1, when the Successor Indication field is "00", it indicates that the MDCP PDU is a single MDCP PDU; when the Successor Indication field is "01", it indicates that the MDCP PDU is the first PDU among multiple MDCP PDUs; when the Successor Indication field is "11", it indicates that the MDCP PDU is the middle PDU among multiple MDCP PDUs; when the Successor Indication field is "10", it indicates that the MDCP PDU is the last PDU among multiple MDCP PDUs.

[0123] It is understood that the values ​​and corresponding meanings of the subsequent indication field shown in Table 1 are only examples. The embodiments of the present application do not limit the length of the subsequent indication field, the specific bit value of the subsequent indication field, and the meaning corresponding to the bit value.

[0124] The following describes the design of the Subsequent Indication field based on Table 1, and introduces the transmission scenarios of the MDCP PDU when there is no 00 field in the Subsequent Indication field of the MDCP PDU and when there is a 00 field in the Subsequent Indication field of the MDCP PDU.

[0125] 1. Transmission scenario of MDCP PDU when there is no 00 field in the successor indication field.

[0126] When there is no 00 field in the successor indication field, that is, when the successor indication field length is 2 bits, the value of the successor indication field does not include "00" and its corresponding meaning. The value of the successor indication field includes: "01", "10", and "11".

[0127] When the MDCP PDU is the first among multiple MDCP PDUs, the Successor Indication field of the MDCP PDU may be "01". When the MDCP PDU is the middle among multiple MDCP PDUs, the Successor Indication field of the MDCP PDU may be "11". When the MDCP PDU is a single MDCP PDU or the last among multiple MDCP PDUs, the Successor Indication field of the MDCP PDU may be "10".

[0128] Scenario 1: Multiple MDCP PDUs are successfully transmitted

[0129] Figure 5 The example shows a scenario in which multiple MDCP PDUs are successfully transmitted when there is no 00 field in the subsequent indication field.

[0130] like Figure 5 As shown, terminal 100 can send four MDCP PDUs to Beidou network device 200. Among these four MDCP PDUs, the MDCP PDU with a Subsequent Indication field of "01" is the first MDCP PDU, the MDCP PDU with a Subsequent Indication field of "11" is the middle MDCP PDU, and the MDCP PDU with a Subsequent Indication field of "10" is the last PDU packet. During the normal transmission process of the four MDCP PDUs, Beidou network device 200 can successfully receive the four MDCP PDUs.

[0131] It is understandable that after the terminal 100 sends an MDCP PDU to the Beidou network device 200, the terminal 100 sends a new MDCP PDU to the Beidou network device 200 only after receiving the ACK replied by the Beidou network device 200 for the SLC SDU corresponding to the MDCP PDU.

[0132] Scenario 2: Single MDCP PDU transmission successful

[0133] Figure 6 The example shows a scenario in which a single MDCP PDU is successfully transmitted when there is no 00 field in the subsequent indication field.

[0134] like Figure 6 As shown, the terminal 100 can send a single MDCP PDU to the Beidou network device 200. The subsequent indication field of the MDCP PDU is "10". The Beidou network device 200 can successfully receive the single MDCP PDU.

[0135] Scenario 3: The last MDCP PDU among multiple MDCP PDUs is not received and the waiting timeout occurs.

[0136] Figure 7 The example shows a scenario in which the transmission of multiple MDCP PDUs fails when there is no 00 field in the subsequent indication field.

[0137] like Figure 7 As shown, terminal 100 can send four MDCP PDUs to Beidou network device 200. Among these four MDCP PDUs, the MDCP PDU with a Subsequent Indicator field of "01" is the first MDCP PDU, the MDCP PDU with a Subsequent Indicator field of "11" is the middle MDCP PDU, and the MDCP PDU with a Subsequent Indicator field of "10" is the last MDCP PDU. Beidou network device 200 did not receive the last of the four MDCP PDUs sent by terminal 100. The waiting time of Beidou network device 200 exceeded, and terminal 100's transmission failed, thus completing the transmission normally.

[0138] If a Beidou network device times out at the MDCP layer, that is, the Beidou network device times out at the SLC layer while waiting to receive an SLC SDU. For example, an SLC SDU includes N SLC PDUs, and the maximum time a terminal can receive each SLC PDU is the first duration. If the Beidou network device receives an MDCP PDU at the MDCP layer and still does not receive the next MDCP PDU after the second duration, it is considered a Beidou network device timeout at the MDCP layer. The second duration can be N times the first duration.

[0139] Scenario 4: The last MDCP PDU among multiple MDCP PDUs is not received and the waiting time does not expire.

[0140] Figure 8 The example shows a scenario in which the transmission of multiple MDCP PDUs fails when there is no 00 field in the subsequent indication field.

[0141] like Figure 8As shown, terminal 100 can send four MDCP PDUs to Beidou network device 200. Among these four MDCP PDUs, the MDCP PDU with a Subsequent Indication field of "01" is the first MDCP PDU, the MDCP PDU with a Subsequent Indication field of "11" is the middle MDCP PDU, and the MDCP PDU with a Subsequent Indication field of "10" is the last PDU packet. Beidou network device 200 does not receive the last MDCP PDU of the four MDCP PDUs sent by terminal 100. Beidou network device 200 waits for the timeout, and terminal 100 initiates a new service, namely, sends a new MDCP PDU. This new MDCP PDU is a separate MDCP PDU, and the Subsequent Indication field of this separate MDCP PDU is "10." For example, while sending the MDCP PDU, the terminal experiences an exception and crashes, and then the user initiates another service on the terminal. At this point, Beidou network device 200 might mistake this single MDCP PDU for the last of the four MDCP PDUs previously sent by terminal 100. Beidou network device 200 then combines this single MDCP PDU with three of the four MDCP PDUs received last time into a single MDCP SDU. Consequently, Beidou network device 200 incorrectly reassembles the MDCP SDU.

[0142] 2. Transmission scenario of MDCP PDU when there is a 00 field in the successor indication field.

[0143] The values ​​of the subsequent indication field include: "00", "01", "10", and "11". The corresponding meanings of the values ​​of the subsequent indication field can be referred to the description in Table 1 above.

[0144] Scenario 5: The last PDU in multiple MDCP PDUs is not received and the waiting time does not expire.

[0145] Figure 9 The example shows a scenario in which the transmission of multiple MDCP PDUs fails when there is no 00 field in the subsequent indication field.

[0146] like Figure 9As shown, terminal 100 can send four MDCP PDUs to Beidou network device 200. Among these four MDCP PDUs, the MDCP PDU with a Subsequent Indicator field of "01" is the first MDCP PDU, the MDCP PDU with a Subsequent Indicator field of "11" is the middle MDCP PDU, and the MDCP PDU with a Subsequent Indicator field of "10" is the last PDU packet. Beidou network device 200 does not receive the last MDCP PDU of the four MDCP PDUs sent by terminal 100. Beidou network device 200 waits for the last MDCP PDU to arrive before the timeout. Terminal 100 then sends a separate MDCP PDU with a Subsequent Indicator field of "00." Based on the "00" in the Subsequent Indicator field of this MDCP PDU, Beidou network device 200 can determine that this MDCP PDU is a separate MDCP PDU. Therefore, Beidou network device 200 does not reassemble this separate MDCP PDU with the previously received MDCP PDU into an MDCP SDU. That is, the Beidou network device 200 will not have the problem of misassembling packets.

[0147] The following describes in detail the protocol processing flow of data at the MDCP layer and the SLC layer of the Beidou communication system 10.

[0148] Figure 10 A schematic diagram of the protocol processing flow of data at the MDCP layer and the SLC layer of the Beidou communication system 10 provided in an embodiment of the present application is shown.

[0149] 1. The protocol encapsulation process of the terminal 100 for sending data at the MDCP layer

[0150] like Figure 10 As shown, at the MDCP layer, terminal 100 can split the MDCP SDU (after the padding data and the redundant length indicator field) into one or more fixed-length MDCP segments (M_segement) and add a subsequent indicator field to the header of each MDCP segment to obtain an MDCP PDU. That is, the MDCP PDU includes the M_segement and subsequent indicator fields. Terminal 100 can store the resulting MDCP PDUs in a first-in, first-out order in the MDCP layer transmit buffer (MDCP Tx buffer). The data length of the subsequent indicator field can occupy 2 bits. The meaning of the value of the subsequent indicator field can be as shown in Table 1 above.

[0151] Exemplarily, the terminal 100 may split the MDCP SDU after adding the padding data and the redundant length indication field into three MDCP PDUs. In descending order of high bit, the three MDCP PDUs are MDCP PDU0, MDCP PDU1, and MDCP PDU2. Since MDCP PDU0 is the starting MDCP PDU in the current MDCP SDU, the terminal 100 may set the value of the Subsequent Indication field in MDCP PDU0 to "01." Since MDCP PDU1 is an intermediate MDCP PDU in the current MDCP SDU, the terminal 100 may set the value of the Subsequent Indication field in MDCP PDU1 to "11." Since MDCP PDU2 is the last MDCP PDU in the current MDCP SDU, the terminal 100 may set the value of the Subsequent Indication field in MDCP PDU2 to "10."

[0152] As another example, the terminal 100 may split the MDCP SDU after adding the padding data and the redundant length indication field into two MDCP PDUs. In descending order of high bit, the two MDCP PDUs are MDCP PDU0 and MDCP PDU1. Since MDCP PDU0 is the starting MDCP PDU in the current MDCP SDU, the terminal 100 may set the value of the Subsequent Indication field in MDCP PDU0 to "01." Since MDCP PDU1 is the last MDCP PDU in the current MDCP SDU, the terminal 100 may set the value of the Subsequent Indication field in MDCP PDU1 to "10."

[0153] As another example, the terminal 100 may treat the MDCP SDU after adding the padding data and the redundant length indication field as MDCP PDU0. Since MDCP PDU0 is the only MDCP PDU in the current MDCP SDU, the terminal 100 may set the value of the subsequent indication field in MDCP PDU0 to "00".

[0154] In the embodiment of the present application, due to the limited capabilities of the terminal's underlying layer and the limited data length of a physical frame, the data length that can be sent by an SLC layer is limited by the physical frame length. Therefore, the SLC layer needs to split the SLC SDU into multiple SLC PDUs. The data length in the SLC PDU also limits the data length sent by the MDCP layer. Therefore, the MDCP layer also needs to split an MDCP SDU into one or more MDCP PDUs.

[0155] 2. The terminal 100 performs protocol encapsulation of the sent data at the SLC layer.

[0156] At the SLC layer, the terminal 100 can control the SLC layer's SLC PDU transmission strategy, including the initial transmission and retransmission of the SLC PDU, based on the reception feedback (e.g., ACK) sent by the Beidou network device 200, through the SLC layer transmission state controller. The terminal 100 can obtain the MDCP PDU sent by the MDCP layer as an SLC SDU through the inter-layer interface. After the terminal 100 sends the previous SLC SDU to the Beidou network device 200 and confirms that the Beidou network device 200 has successfully received it, it will obtain the next MDCP PDU from the MDCP layer as the next SLC SDU and send it to the Beidou network device 200.

[0157] Optionally, in a possible implementation, the terminal 100 divides the MDCP SDU into multiple MDCP PDUs at the MDCP layer, and the terminal 100 may transmit the multiple MDCP PDUs to the SLC layer of the terminal 100 together.

[0158] For example, the terminal 100 can split the MDCP SDU after adding padding data and the redundant length indication field into three MDCP PDUs. Among them, in order from high bit to low bit, the three MDCP PDUs are MDCP PDU0, MDCP PDU1, and MDCP PDU2. At the SLC layer, the terminal 100 first obtains MDCP PDU0 issued by the MDCP layer through the inter-layer interface. The terminal 100 can send MDCP PDU0 as the first SLC SDU of the SLC layer in this message transmission process to the Beidou network device 200. After the terminal 100 determines that the data of the first SLC SDU has been sent to the Beidou network device 200, the terminal 100 can obtain MDCP PDU1 from the MDCP layer and send MDCP PDU1 to the Beidou network device 200 as the second SLC SDU in this message transmission process. After the terminal 100 determines that the Beidou network device 200 has sent the data of the second SLC SDU to the Beidou network device 200, the terminal 100 can obtain MDCP PDU2 from the MDCP layer and send MDCP PDU2 to the Beidou network device 200 as the last SLC SDU in this message transmission process.

[0159] The above examples are only used to explain the present application and should not be construed as limiting.

[0160] At the SLC layer, the terminal 100 can segment the SLC SDU into one or more fixed-length SLC segment data (S_segement) and add frame header information to the header of each S_segement to obtain an SLC PDU. The frame header information includes the SAI field, the total number of frames field, and the frame sequence number field.

[0161] (1) The SAI field can occupy 1 bit. The value of the SAI field can be "0" or "1". The terminal 100 can determine whether the SLC PDU to be sent currently belongs to an SLC SDU that has not been sent. If so, the terminal 100 can set the value of the SAI field in the SLC PDU to be different from the value of the SAI field of the SLC PDU in the previous SLC SDU session (including the SLC SDU initial transmission session or the SLC SDU retransmission session); if not, the terminal 100 can set the value of the SAI field in the SLC PDU to be the same as the value of the SAI field of the SLC PDU in the previous SLC SDU session. When the value of the SAI field in the SLC PDU is the same as the value of the SAI field of the SLC PDU in the previous SLC SDU session, it indicates that the SLC PDU is retransmitted data.

[0162] It is understood that the SAI field has a preset initial value, and the SAI field of the first SLC SDU sent by the terminal 100 to the Beidou network device 200 is the preset initial value. If the SAI field of the first SLC SDU received by the Beidou network device 200 is not the preset initial value, the Beidou network device 200 can directly discard the SLC SDU. The preset initial value of the SAI field in the SLC SDU can be 0 or other values. This application does not limit the preset initial value of the SAI field.

[0163] For example, during the entire application layer message transmission process, the terminal 100 needs to transmit three SLC SDUs. Each SLC SDU may include four SLC PDUs. The SAI field values ​​of the four SLC PDUs in the first SLC SDU may all be "0," and the SAI field values ​​of the four SLC PDUs in the second SLC SDU may all be "1." The SAI field values ​​of the four SLC PDUs in the third SLC SDU may all be "0."

[0164] The above examples are only used to explain the present application and should not be construed as limiting.

[0165] (2) The Total Frames field may be used to indicate the total number of SLC PDUs in the SLC SDU to which the SLC PDU belongs. When an SLC SDU in the BeiDou communication system 10 can be divided into a maximum of four fixed-length SLC segments (S_segement), the Total Frames field may occupy 2 bits.

[0166] For example, when an SLC SDU includes only one SLC PDU, the value of the Total Frames field of the only SLC PDU in the SLC SDU may be "00". When an SLC SDU includes two SLC PDUs, the value of the Total Frames field of both SLC PDUs in the SLC SDU may be "01". When an SLC SDU includes three SLC PDUs, the value of the Total Frames field of all three SLC PDUs in the SLC SDU may be "10". When an SLC SDU includes four SLC PDUs, the value of the Total Frames field of all four SLC PDUs in the SLC SDU may be "11".

[0167] The above examples are only used to explain the present application and should not be construed as limiting.

[0168] (3) Frame Sequence Number field, which can be used to indicate the sequence number of the SLC PDU within the SLC SDU to which it belongs. When an SLC SDU in the BeiDou communication system 10 can be divided into a maximum of four fixed-length SLC segments (S_segement), the frame sequence number field can occupy 2 bits.

[0169] For example, when an SLC SDU includes only one SLC PDU, the value of the frame sequence number field of the only SLC PDU in the SLC SDU may be "00". When an SLC SDU includes two SLC PDUs, the value of the frame sequence number field in the first SLC PDU in the SLC SDU may be "00", and the value of the frame sequence number field in the second SLC PDU in the SLC SDU may be "01". When an SLC SDU includes three SLC PDUs, the value of the frame sequence number field in the first SLC PDU in the SLC SDU may be "00", the value of the frame sequence number field in the second SLC PDU in the SLC SDU may be "01", and the value of the frame sequence number field in the third SLC PDU in the SLC SDU may be "10". When the SLC SDU includes 4 SLC PDUs, the value of the frame sequence number field in the first SLC PDU in the SLC SDU can be "00", the value of the frame sequence number field in the second SLC PDU in the SLC SDU can be "01", the value of the frame sequence number field in the third SLC PDU in the SLC SDU can be "10", and the value of the frame sequence number field in the fourth SLC PDU in the SLC SDU can be "11".

[0170] The above examples are only used to explain the present application and should not be construed as limiting.

[0171] 3. The Beidou network device 200 performs protocol parsing of received data at the SLC layer.

[0172] At the SLC layer, after the Beidou network device 200 receives the SLC PDU from the terminal 100, it can determine whether all SLC PDUs in an SLC SDU have been received based on the frame header information of the SLC PDU. If so, the Beidou network device 200 can splice the received one or more SLC PDUs into an SLC SDU in order from small to large according to the value of the frame sequence number field. If not all SLC PDUs in an SLC SDU have been received, the Beidou network device 200 can send feedback information (for example, ACK) to notify the terminal 100 to retransmit the unreceived SLC PDU after the SLC layer receiving window ends. After splicing the SLC SDU, the Beidou network device 200 can report the SLC SDU to the MDCP layer through the inter-layer interface as an MDCP PDU.

[0173] Among them, the Beidou network device 200 can control the SLC layer feedback information (e.g., ACK) sending strategy and SLC PDU splicing based on the SAI field in the SLC PDU through the SLC layer reception state controller at the SLC layer. The duration of the SLC layer reception state controller is the maximum retransmission time of the SLC PDU on the terminal 100.

[0174] For example, the SAI value of the first SLC PDU in the first SLC SDU received by the Beidou network device 200 may be "0", the total number of frames may be "11", and the frame sequence number may be "00". The SAI value of the second SLC PDU in the first SLC SDU may be "0", the total number of frames may be "11", and the frame sequence number may be "01". The SAI value of the third SLC PDU in the first SLC SDU may be "0", the total number of frames may be "11", and the frame sequence number may be "10". The SAI value of the fourth SLC PDU in the first SLC SDU may be "0", the total number of frames may be "11", and the frame sequence number may be "11". The Beidou network device 200 may concatenate these four SLC PDUs into the first SLC SDU in ascending order of frame sequence numbers and report it to the MDCP layer as MDCP PDU0 of the MDCP layer. The Beidou network device 200 may store the MDCP PDU0 in the MDCP layer receiving buffer (MDCP Rx buffer), wherein the value of the subsequent indication field in the MDCP PDU0 is "01".

[0175] The SAI value of the first SLC PDU in the second SLC SDU received by the Beidou network device 200 may be "1," the total number of frames may be "11," and the frame sequence number may be "00." The SAI value of the second SLC PDU in the second SLC SDU may be "1," the total number of frames may be "11," and the frame sequence number may be "01." The SAI value of the third SLC PDU in the second SLC SDU may be "1," the total number of frames may be "11," and the frame sequence number may be "10." The SAI value of the fourth SLC PDU in the second SLC SDU may be "1," the total number of frames may be "11," and the frame sequence number may be "11." The Beidou network device 200 may concatenate these four SLC PDUs into the second SLC SDU in ascending order of frame sequence numbers and report it to the MDCP layer as MDCP PDU1. The Beidou network device 200 may store the MDCP PDU1 in the MDCP layer receiving buffer (MDCP Rx buffer), wherein the value of the subsequent indication field in the MDCP PDU1 is "10".

[0176] The SAI value of the first SLC PDU in the third SLC SDU received by the Beidou network device 200 may be "0," the total number of frames may be "11," and the frame sequence number may be "00." The SAI value of the second SLC PDU in the third SLC SDU may be "0," the total number of frames may be "11," and the frame sequence number may be "01." The SAI value of the third SLC PDU in the third SLC SDU may be "0," the total number of frames may be "11," and the frame sequence number may be "10." The SAI value of the fourth SLC PDU in the third SLC SDU may be "0," the total number of frames may be "11," and the frame sequence number may be "11." The Beidou network device 200 may concatenate these four SLC PDUs into a third SLC SDU in ascending order of frame sequence numbers and report it to the MDCP layer as MDCP PDU2. The Beidou network device 200 may store the MDCP PDU2 in the MDCP layer receiving buffer (MDCP Rx buffer), wherein the value of the subsequent indication field in the MDCP PDU2 is "11".

[0177] The above examples are only used to explain the present application and should not be construed as limiting.

[0178] 4. The Beidou network device 200 performs protocol parsing of received data at the MDCP layer.

[0179] At the MDCP layer, after receiving all MDCP PDUs of an MDCP SDU sent by the terminal 100, the Beidou network device 200 may aggregate multiple MDCP PDUs in a receiving time sequence based on the subsequent indication field in the MDCP PDU to obtain an MDCP SDU.

[0180] After the Beidou network device 200 obtains an MDCP PDU with a Subsequent Indicator field value of "11" from the SLC layer, it can retrieve all MDCP PDUs from the MDCP Rx buffer and concatenate them according to the Subsequent Indicator field value and the order of receipt time. After concatenation, it removes the redundant indicator field and padding data to obtain an MDCP SDU. The Beidou network device 200 can report the MDCP SDU to the application layer through the inter-layer interface as an application layer message.

[0181] The following describes the segmentation process of the MDCP layer MDCP SDU when entering the station.

[0182] The following description uses the example of the terminal 100 segmenting an MDCP SDU into one or more MDCP PDUs. The terminal 100 segmenting an MDCP SDU into one or more MDCP PDUs may include the following steps:

[0183] 1. The data compressed and encrypted by the application layer of the terminal 100 is used as the MDCP SDU of the MDCP layer. The data size of the MDCP SDU can be recorded as DataSizeOfMsdu;

[0184] 2. Terminal 100 can calculate the number of segments (SegmentNumOfMsdu) of an MDCP SDU, the data portion of each MDCP PDU obtained by segmenting the MDCP SDU, and the padding data based on the transmission capability provided by the SLC layer. The transmission capability of the SLC layer is obtained from the PHY layer via the inter-layer transmission interface. The transmission capability of the SLC layer refers to the specific data length of an SLC PDU that the SLC layer can transmit. The data length of an SLC PDU that the SLC layer can transmit is determined by the data length of a physical frame in the PHY layer.

[0185] 3. The terminal 100 adds padding data and a redundant length indicator field to the MDCP SDU according to the number of segments SegmentNumOfMsdu and the sequence number of the MDCP PDU, and then segments it into multiple MDCP PDUs. The redundant length indicator field is used to indicate the data length of the padding data. The terminal 100 then determines the subsequent indication for each MDCP PDU, ultimately forming a complete MDCP PDU. The subsequent indication needs to indicate the first MDCP PDU, the middle MDCP PDU, and the last MDCP PDU among the multiple MDCP PDUs. If the current SegmentNumOfMsdu = 1, the subsequent indication needs to indicate that the current MDCP PDU is a single MDCP PDU. If SegmentNumOfMsdu = 4, the subsequent indication requires 4 states, 2 bits.

[0186] 4. The terminal 100 transmits the MDCP PDU to the SLC layer through the inter-layer interface as the SLC SDU of the SLC layer.

[0187] Next, the MDCP PDU reassembly process at the MDCP layer upon inbound transmission is described.

[0188] The following is an example of the Beidou network device 200 reassembling one or more received MDCP PDUs into an MDCP SDU. The Beidou network device 200 reassembling one or more received MDCP PDUs into an MDCP SDU may include the following steps:

[0189] 1. At the SLC layer, the BeiDou network device 200 calculates the length of an MDCP PDU based on the frame sequence number and total number of frames carried in the received SLC PDU and the frame length of the SLC PDU obtained through blind decoding. The BeiDou network device 200 then reports the calculated length of the MDCP PDU to the MDCP layer.

[0190] Specifically, the incoming physical layer frame length is a fixed frame length from a finite set. Thus, upon successfully receiving an incoming physical layer frame (after successfully decoding each frame length), the physical layer of the Beidou network device 200 learns the corresponding physical layer frame length. After the SLC layer receives multiple SLC frames (each corresponding to a physical layer frame), the SLC informs the MDCP layer of the packet length of its SLC SDU, or MDCP PDU.

[0191] Then, the Beidou network device 200 can obtain the length of the packet after being packaged based on the length of each MDCP PDU, and then obtain the padding length by parsing the bit indicated by the redundant length, thereby removing the padding bit to obtain the MDCP SDU data.

[0192] 2. At the MDCP layer, the Beidou network device 200 combines one or more received MDCP PDUs into a complete MDCP SDU data packet according to the subsequent indication field of each MDCP PDU.

[0193] If the subsequent indication field of the MDCP PDU indicates that the MDCP PDU is a single MDCP PDU, the Beidou network device 200 treats the single MDCP PDU as an MDCP SDU data packet.

[0194] If the successor indicator bit of the current MDCP PDU indicates that the current MDCP PDU is not the first MDCP PDU among multiple MDCP PDUs, nor is it a single MDCP PDU (i.e., the last MDCP PDU or an intermediate MDCP PDU among multiple MDCP PDUs), the Beidou network device 200 removes the successor indicator field from the currently received MDCP PDU and packages it with the previously received MDCP PDUs without the successor indicator field in sequence. This continues until the successor indicator field of the received MDCP PDU indicates that the current MDCP PDU is the last MDCP PDU. The Beidou network device 200 removes the successor indicator field from the last MDCP PDU and packages it with the previously packaged data, ultimately obtaining an MDCP SDU data packet.

[0195] 3. The Beidou network device 200 passes the MDCP SDU to the application layer for processing (such as decryption and decompression, etc.).

[0196] It is understandable that, due to the fact that terminals can retransmit during inbound transmission, for example, during a transmission, terminal 100 sends SLC PDU0 to Beidou network device 200 and then retransmits the same SLC PDU0 to Beidou network device 200. Beidou network device 200 needs to determine whether the received SLC PDU is a retransmission. If so, it discards the retransmitted SLC PDU at the SLC layer. After receiving all MDCP PDUs from the MDCP layer, Beidou network device 200 assembles them into MDCP SDU packets, parses the Redundant Length Indicator field in the MDCP SDU, removes the padding data, and then passes it to the application layer for subsequent decryption and decompression operations.

[0197] Table 2 exemplarily shows that a single MDCP PDU is reassembled into an MDCP SDU.

[0198] Table 2

[0199]

[0200] As shown in Table 2, the Beidou network 200 device combines a single MDCP PDU into an MDCP SDU as an example. The Beidou network device 200 can Figure 3The length of the MDCP PDU packet is calculated based on the length of the code data shown in the figure. Then, the length of the MDCP SDU can be obtained based on the length of the MDCP PDU. As shown in Table 2, taking the coded data (including the code block and the check bit) as 512 bits as an example, the length of an SLC layer PDU is also the length of a code block, that is, the length of the coded data minus the length of the check bit (that is, 512 bits - 24 bits), which is 488 bits. Among them, the length of the frame header in the SLC PDU is 64 bits, so the length of the S_segment of the SLC layer is (448 bits - 64 bits) = 424 bits. When an SLC SDU is divided into only one S_segment, the length of the SLC SDU is also the length of an MDCP PDU, which is 424 bits. The length of the MDCP PDU is also the length of an SLC SDU. When the MDCP SDU contains only one MDCP PDU (including the successor indicator and M_segment), the padding (237 bits) is obtained by subtracting the length of the successor indicator (2 bits), the length of the redundant length indicator (8 bits), and the length of the MDCP SDU (assuming 177 bits).

[0201] It should be understood that Table 2 is merely an example and does not limit the application embodiments.

[0202] Table 3 exemplarily shows that one MDCP SDU is divided into multiple MDCP PDUs and reassembled.

[0203] Table 3

[0204]

[0205] As shown in Table 3, the terminal 100 divides an MDCP SDU into two MDCP PDUs. As shown in Table 3, the terminal 100 receives a data packet at the MDCP layer, which is an MDCP SDU with a data length of 2106 bits. The terminal 100 obtains the coded data (i.e. Figure 3 The data length of the code data shown in FIG is 512 bits, and the length of the check bit is 24 bits. Therefore, the terminal 100 can determine the transmission capacity that the SLC layer can provide, that is, the data length of an SLC PDU that the SLC layer can transmit is the code data (i.e. Figure 3The data length of the code data (shown in the figure) minus the length of the check bit and the length of the SLC PDU header is 424 bits. Terminal 100 can then determine the number of segments of the MDCP SDU based on the data length of the SLC PDU, namely, the two MDCP PDUs, the data length of each MDCP PDU (the data length of the first MDCP PDU is 1694 bits, and the data length of the second MDCP PDU is 422 bits), and the padding length (e.g., 2 bits).

[0206] It should be understood that Table 3 is merely an example and does not limit the embodiments of the present application.

[0207] The following describes a protocol encapsulation architecture for outbound data of a Beidou communication system 10 provided in an embodiment of the present application.

[0208] Figure 11A A schematic diagram of a protocol encapsulation architecture for outbound data of a Beidou communication system 10 provided in an embodiment of the present application is shown.

[0209] like Figure 11A As shown, the BeiDou short message transmission protocol layer in the BeiDou network device 200 can be an application layer protocol, a message data convergence protocol (MDCP), a satellite link control protocol (SLC), and a physical layer protocol (PHY). Among them, the BeiDou network device 200 can include a BeiDou ground transceiver station 22, a BeiDou central station 23, and a BeiDou short message fusion communication platform 24. The BeiDou ground transceiver station 22 can be used to be responsible for the protocol processing of the PHY layer. The BeiDou central station 23 can be used to be responsible for the protocol processing of the SLC layer and the MDCP layer. The BeiDou short message fusion communication platform 24 can be used to be responsible for the protocol processing of the APP layer.

[0210] When the Beidou network device 200 sends data to the terminal 100, the workflow of the Beidou short message transmission protocol in the Beidou network device 200 may be as follows:

[0211] At the APP layer, the Beidou network device 200 may compress the original data into compressed data using a compression algorithm and add a compression indicator field to the front of the compressed data. The compression indicator field may be used to indicate the compression algorithm type used for the compressed data. The Beidou network device 200 may then encrypt the compressed data to obtain encrypted data and add an encryption algorithm field to the header of the encrypted data. The encryption algorithm field indicates the encryption algorithm type used for the encrypted data. The Beidou network device 200 may encapsulate the encrypted data, the compression indicator field, and the encryption indicator field into an application layer message and send it to the MDCP layer. The application layer message may include a message header and message data. The message header may include a compression indicator field, an encryption indicator field, and the like. The message data includes the encrypted data.

[0212] Optionally, in a possible implementation, the Beidou network device 200 divides the MDCP SDU into multiple MDCP PDUs at the MDCP layer, and the Beidou network device 200 may transmit the multiple MDCP PDUs to the SLC layer of the Beidou network device 200 together.

[0213] At the MDCP layer, the Beidou network device 200 can obtain the application layer message sent by the APP layer through the inter-layer interface and use the application layer message as an MDCP SDU. At the MDCP layer, the Beidou network device 200 can split an MDCP SDU into one or more fixed-length MDCP segment data (M_segement) and add a successor indication field to the header of each MDCP segment data to obtain an MDCP PDU. That is, the MDCP PDU includes an M_segement and a successor indication field. The successor indication field can be used to indicate whether the current MDCP PDU is the starting MDCP PDU, an intermediate MDCP PDU, or the last MDCP PDU of multiple MDCP PDUs sent continuously; or a single MDCP PDU sent separately.

[0214] At the SLC layer, the BeiDou network device 200 can obtain the MDCP PDU sent by the MDCP layer through the inter-layer interface as an SLC SDU. At the SLC layer, the BeiDou network device 200 can segment the SLC SDU into one or more (up to 4) fixed-length SLC segments (S_segement) and add frame header information to the header of each S_segement to obtain an SLC PDU.

[0215] At the PHY layer, the Beidou network device 200 can obtain the SLC PDU sent by the SLC layer through the inter-layer interface. The Beidou network device 200 can obtain the SLC PDU of one or more users from the SLC layer. The Beidou network device 200 can splice the SLC PDUs of multiple users together, add the frame header of the physical frame (such as the version number) as the code block of the PHY layer, and add a check bit (such as a cyclic redundancy check (CRC) code) at the end of the code block, and encode the code block and CRC code (such as polar coding). The encoded physical frame plus the reserved segment can form the coded data of the message branch (S2C_d branch) of a fixed-length physical time slot. Among them, the Beidou network device 200 can put multiple SLC PDUs of a user into different physical frames respectively. Then, the Beidou network device 200 combines the coded data of the S2C_d branch and the pilot information of the pilot branch (S2C_p branch) to form pilot coded data, that is, outbound data. The Beidou network device 200 can send outbound data to the Beidou short message satellite 21, which is then relayed to the terminal 100 via the Beidou short message satellite 21.

[0216] It is understood that the pilot information of the S2C_p branch is related to the satellite beam. When the satellite beam number is known, the pilot information of the S2C_p branch is also known and does not need to be decoded. However, the coded data of the S2C_d branch needs to be decoded.

[0217] The following describes a protocol parsing architecture for outbound data of a Beidou communication system 10 provided in an embodiment of the present application.

[0218] Figure 11B A schematic diagram of a protocol parsing architecture for outbound data of a Beidou communication system 10 provided in an embodiment of the present application is shown.

[0219] like Figure 11B As shown, the Beidou short message transmission protocol layer of the terminal 100 can be divided into an application layer (application layer protocol), a message data convergence protocol (MDCP), a satellite link control protocol (SLC) and a physical layer (PHY).

[0220] When the terminal 100 receives data sent by the Beidou network device, the workflow of the Beidou short message transmission protocol layer of the terminal 100 can be as follows:

[0221] At the PHY layer, the terminal 100 can obtain the pilot coded data after modulation and spread spectrum sent by the Beidou network device 200. The terminal 100 can despread the received spread spectrum modulated data (spread+modulated data) to obtain modulated data (modulated data). Then, the terminal 100 can demodulate the modulated data to obtain pilot coded data (pilot+data). Then, the terminal 100 can remove the pilot information in the pilot coded data to obtain coded data (code data). Then, the terminal 100 can decode the coded data and verify the integrity of the code block (code block) through the check data in the check bit field. If complete, the terminal 100 can extract the code block (code block) and present it to the SLC layer through the inter-layer interface as the SLC PDU of the SLC layer.

[0222] Here, the pilot coded data is the outbound data sent by the Beidou network device 200, and the outbound data consists of the coded data of the S2C_d branch and the pilot information of the pilot branch (S2C_p branch).

[0223] At the SLC layer, the terminal 100 can concatenate SLC PDUs belonging to the same SLC SDU into one SLC SDU based on the frame header information of the SLC PDU. The terminal 100 can present the SLC SDU to the MDCP layer through the inter-layer interface as an MDCP PDU of the MDCP layer.

[0224] At the MDCP layer, the terminal 100 may concatenate all MDCP PDUs belonging to the same MDCP SDU into one MDCP SDU. The terminal 100 may present the MDCP SDU to the APP layer via an inter-layer interface as an application layer message received by the APP layer.

[0225] At the APP layer, the terminal 100 may decrypt and decompress the application layer message based on the message header of the application layer message to obtain the original data.

[0226] In the embodiments of the present application, the above-mentioned protocol processing process is only an example, and the present application does not limit the specific operations of the protocol processing.

[0227] The following describes the segmentation process of the MDCP SDU at the MDCP layer when outbound.

[0228] The following description uses the Beidou network device 200 as an example to illustrate how to segment an MDCP SDU into one or more MDCP PDUs. The Beidou network device 200 may segment an MDCP SDU into one or more MDCP PDUs, including the following steps:

[0229] 1. The data of the application layer of the Beidou network device 200 is compressed and encrypted as the MDCP SDU of the MDCP layer. The data size of the MDCP SDU can be recorded as DataSizeOfMsdu;

[0230] 2. The BeiDou network device 200 can calculate the number of segments of an MDCP SDU (SegmentNumOfMsdu) and the data portion of each MDCP PDU obtained by segmenting the MDCP SDU according to the transmission capacity provided by the SLC layer;

[0231] 3. The Beidou network device 200 determines the successor indication of each MDCP PDU based on the number of segments SegmentNumOfMsdu and the sequence number of the MDCP PDU, and finally forms a complete MDCP PDU; wherein the successor indication needs to indicate the first MDCP PDU, the middle MDCP PDU, and the last MDCP PDU in multiple MDCP PDUs; if the current SegmentNumOfMsdu=1, the successor indication needs to indicate that the current MDCP PDU is a single MDCP PDU; if SegmentNumOfMsdu=4, the successor indication needs 4 states, 2 bits;

[0232] 4. The Beidou network device 200 passes the MDCP PDU to the SLC layer through the inter-layer interface as the SLC SDU of the SLC layer.

[0233] Next, the MDCP PDU reassembly process at the MDCP layer during outbound transmission is described.

[0234] The following description uses the example of the terminal 100 reassembling one or more received MDCP PDUs into an MDCP SDU. The terminal 100 reassembling one or more received MDCP PDUs into an MDCP SDU may include the following steps:

[0235] 1. At the SLC layer, terminal 100 calculates the length of an MDCP PDU based on the frame sequence number and total number of frames carried in the received SLC PDU, as well as the frame length of an SLC PDU. Terminal 100 then reports the calculated length of an MDCP PDU to the MDCP layer.

[0236] 2. At the MDCP layer, the terminal 100 combines one or more received MDCP PDUs into a complete MDCP SDU data packet according to the subsequent indication field of each MDCP PDU.

[0237] If the subsequent indication field of the MDCP PDU indicates that the MDCP PDU is a single MDCP PDU, the terminal 100 regards the single MDCP PDU as an MDCP SDU data packet.

[0238] If the successor indicator field of the current MDCP PDU indicates that the current MDCP PDU is not the first MDCP PDU among multiple MDCP PDUs, nor is it a single MDCP PDU (i.e., the last MDCP PDU or an intermediate MDCP PDU among multiple MDCP PDUs), the terminal 100 removes the successor indicator field from the currently received MDCP PDU and sequentially groups it with the previously received MDCP PDUs without the successor indicator field. This continues until the successor indicator field of the received MDCP PDU indicates that the current MDCP PDU is the last MDCP PDU. The terminal 100 removes the successor indicator field from the last MDCP PDU and groups it with the previously grouped data, ultimately obtaining an MDCP SDU data packet.

[0239] 3. The terminal 100 passes the MDCP SDU to the application layer for processing (eg, decryption and decompression, etc.).

[0240] The following describes a data transmission control method in a satellite communication system provided in an embodiment of the present application.

[0241] Figure 11C A flow chart of a data transmission control method in a satellite communication system provided in an embodiment of the present application is shown.

[0242] like Figure 11C As shown, the data transmission control method in the Beidou communication system may include:

[0243] S1101. The terminal 100 adds padding data and a redundant length indication field to a first message data convergence layer service data unit MDCP SDU at the message data convergence layer MDCP layer, and then divides the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDUs.

[0244] Wherein, M is a positive integer; the redundant length indication field is used to indicate the data length of the padding data, the M MDCP PDUs include a first MDCP PDU, the header information of the first MDCP PDU includes a subsequent indication field, and the subsequent indication field is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; the terminal sends the first MDCP PDU to the Beidou network device.

[0245] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0246] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0247] S1102 : The terminal 100 sends a first MDCP PDU to the Beidou network device 200 .

[0248] S1103. The Beidou network device 200 receives M data convergence layer protocol data units (MDCPPDUs) sent by the terminal.

[0249] S1104 : The Beidou network device 200 concatenates the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer.

[0250] Some possible implementations performed by the terminal 100 are described below.

[0251] In a possible implementation, after adding padding data and a redundant length indication field to a first message data convergence layer service data unit (MDCP SDU) at a message data convergence layer (MDCP) layer, the terminal 100 divides the first message data convergence layer service data unit (MDCP SDU) into M data convergence layer protocol data units (MDCP PDUs). Specifically, the terminal 100 generates an application layer message at an application layer; and the terminal 100 uses the application layer message as a first MDCP SDU at the MDCP layer, and after adding padding data and a redundant length indication field to the first MDCP SDU, divides the first MDCP SDU into M MDCP PDUs.

[0252] In one possible implementation, the terminal 100 uses the application layer message as a first MDCP SDU at the MDCP layer, and after adding padding data and a redundant length indicator field to the first MDCP SDU and before dividing it into M MDCP PDUs, the method further includes: the terminal 100 obtaining original data; the terminal 100 compressing the original data at the application layer to obtain compressed data; the terminal 100 encrypting the compressed data at the application layer to obtain encrypted data; the terminal 100 adding message header information to a header of the encrypted data to obtain an application layer message; wherein the message header information includes a compression indication field and an encryption indication field, the compression indication field being used to indicate a compression algorithm used when compressing the original data, and the encryption indication field being used to indicate an encryption algorithm used when encrypting the compressed data.

[0253] In one possible implementation, the terminal 100 sends the first MDCP PDU to the Beidou network device, specifically including: the terminal 100 transmits the first MDCP PDU to the satellite link control SLC layer as the first satellite link control layer service data unit SLC SDU of the SLC layer; the terminal 100 divides the first SLC SDU into N satellite link control layer protocol data units SLC PDUs at the SLC layer, where N is a positive integer; wherein the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a service data unit alternation indication SAI field, a total number of frames field, and a frame sequence number field; the SAI field is used to indicate whether the first SLC PDU is retransmitted data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU; the terminal 100 sends the first SLC PDU to the Beidou network device.

[0254] In this way, by flipping the value of the SAI field of the SLC PDU, it is indicated whether the SLC PDU is retransmitted data, which can ensure that the Beidou network device can identify whether the received SLC PDU is retransmitted data, thereby ensuring continuous data transmission in the Beidou communication system.

[0255] In one possible implementation, the terminal 100 sends the first SLC PDU to the Beidou network device, specifically including: the terminal 100 sends the first SLC PDU from the SLC layer to the physical PHY layer as the first coding block of the PHY layer; the terminal 100 adds check bit information at the end of the first coding block at the PHY layer, and encodes the first coding block and the check bit information to obtain first coded data; the terminal 100 inserts pilot information into the first coded data at the PHY layer to obtain first pilot data; the terminal 100 modulates the first pilot data and the synchronization header of the first pilot data at the PHY layer to obtain first modulated data and a first modulation synchronization header; the terminal 100 spreads the first modulated data and the modulation synchronization header at the PHY layer to obtain first spread spectrum modulated data; the terminal 100 sends the first spread spectrum modulated data as the first physical frame to the Beidou network device at the PHY layer.

[0256] In a possible implementation, the terminal 100 determines the data length of the first MDCP PDU according to the data length of the first MDCP SDU and the data length of the first physical frame.

[0257] In this way, the terminal 100 can know how to split the MDCP SDU into multiple MDCP PDUs.

[0258] The following introduces some possible implementations of the Beidou network device 200.

[0259] In a possible implementation, the Beidou network device 200 splices the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: when the second MDCP PDU received by the Beidou network device 200 subsequently indicates that the second MDCP PDU is the last one of the M MDCP PDUs, the Beidou network device 200 splices the M MDCP PDUs into a first MDCP SDU at the MDCP layer, and reports the first MDCP SDU as an application layer message from the MDCP layer to the application layer.

[0260] In one possible implementation, the application layer message includes message header information and encrypted data, the message header information includes an encryption indication field and a compression indication field, the compression indication field is used to indicate the compression algorithm used by the terminal 100 to compress the original data into compressed data, and the encryption indication field is used to indicate the encryption algorithm used by the terminal 100 to encrypt the compressed data into encrypted data; the method also includes: the Beidou network device 200 decrypts the encrypted data in the application layer message at the application layer using the encryption algorithm indicated by the encryption indication field in the application layer message to obtain compressed data; the Beidou network device 200 decompresses the compressed data at the application layer using the compression algorithm indicated by the compression indication field in the application layer message to obtain the original data.

[0261] In one possible implementation, it also includes: the Beidou network device 200 splices N SLC PDUs into a first SLC SDU at the SLC layer, and reports the first SLC SDU as a first MDCP PDU from the SLC layer of the Beidou network device 200 to the MDCP layer of the Beidou network device 200; wherein, the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a service data unit alternating indication SAI field, a total number of frames field, and a frame sequence number field; the SAI field is used to indicate whether the first SLC PDU is retransmitted data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU.

[0262] In a possible implementation, the BeiDou network device 200 concatenates N SLC PDUs into a first SLC SDU at the SLC layer, and uses the first SLC SDU as the first MDCP. Before the PDU is reported from the SLC layer of the Beidou network device 200 to the MDCP layer of the Beidou network device 200, the method also includes: the Beidou network device 200 obtains the first spread spectrum modulated data sent by the terminal 100 at the PHY layer; the Beidou network device 200 despreads the first spread spectrum modulated data at the PHY layer to obtain the first modulated data and the first modulation synchronization header; the Beidou network device 200 demodulates the first modulated data and the first modulation synchronization header at the PHY layer to obtain the first pilot data and the first synchronization header; the Beidou network device 200 removes the pilot information in the first pilot data at the PHY layer to obtain the first coded data; the Beidou network device 200 decodes the first coded data at the PHY layer to obtain the first coded block and the first verification information; the Beidou network device 200 verifies the first coded block based on the first verification information at the PHY layer, and after the verification is successful, uses the first coded block as the first SLC in the first SLC SDU in the SLC layer of the Beidou network device 200 The PDU is presented from the PHY layer to the SLC layer of the Beidou network device 200 .

[0263] In a possible implementation, the Beidou network device 200 splices M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: after the Beidou network device 200 removes the successor indication field of each MDCP PDU in the M MDCP PDUs at the MDCP layer, the M MDCP PDUs are spliced ​​into a first MDCP SDU in the order indicated by the successor indication of each MDCP PDU in the M MDCP PDUs.

[0264] Figure 11D A flow chart of a data transmission control method in a satellite communication system provided in an embodiment of the present application is shown.

[0265] like Figure 11D As shown, the data transmission control method in the Beidou communication system may include:

[0266] S2101. The Beidou network device 200 divides a first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDUs at the message data convergence layer MDCP layer.

[0267] Wherein, M is a positive integer; the M MDCP PDUs include a first MDCP PDU, the header information of the first MDCP PDU includes a subsequent indication field, and the subsequent indication field is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; the Beidou network device 200 sends the first MDCP PDU.

[0268] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0269] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0270] S2102 . The Beidou network device 200 sends a first MDCP PDU to the terminal 100 .

[0271] S2103. The terminal 100 receives M data convergence layer protocol data units MDCP PDUs sent by the terminal 100.

[0272] S2104: The terminal 100 concatenates the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer.

[0273] The following introduces some possible implementations of the Beidou network device 200.

[0274] In a possible implementation, the Beidou network device 200 divides the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDU at the message data convergence MDCP layer, specifically including: the Beidou network device 200 generates an application layer message at the application layer; the Beidou network device 200 uses the application layer message as the first MDCP SDU at the MDCP layer, and divides the first MDCP SDU into M MDCP PDUs.

[0275] In one possible implementation, the Beidou network device 200 generates an application layer message at the application layer, specifically including: the Beidou network device 200 obtains original data; the Beidou network device 200 compresses the original data at the application layer to obtain compressed data; the Beidou network device 200 encrypts the compressed data at the application layer to obtain encrypted data; the Beidou network device 200 adds message header information to the encrypted data header to obtain an application layer message; wherein the message header information includes a compression indication field and an encryption indication field, the compression indication field is used to indicate the compression algorithm used when compressing the original data, and the encryption indication field is used to indicate the encryption algorithm used when encrypting the compressed data.

[0276] In a possible implementation, the Beidou network device 200 sends the first MDCP PDU, specifically including: the Beidou network device 200 transmits the first MDCP PDU to the satellite link control SLC layer as the first satellite link control layer service data unit SLC SDU of the SLC layer; the Beidou network device 200 divides the first SLC SDU into N satellite link control layer protocol data units SLC PDUs at the SLC layer, where N is a positive integer; wherein the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a first user ID field and a first frame type field, the first user ID field is used to indicate the terminal 100 receiving the first user frame, and the first frame type field is used to indicate the frame type of the first user frame; the Beidou network device 200 sends the first SLC PDU.

[0277] In a possible implementation, the Beidou network device 200 sends a first physical frame and a second physical frame, including: the Beidou network device 200 adds first check bit information to the end of the first physical frame at the PHY layer, encodes the first physical frame and the first check bit information to obtain first coded data, adds second check bit information to the end of the second physical frame, and encodes the second physical frame and the second check bit information to obtain second coded data; the Beidou network device 200 modulates the first coded data and the first reserved field of the first coded data at the PHY layer to obtain first modulated data, and modulates the second coded data and the second reserved field of the second coded data to obtain second modulated data; the Beidou network device 200 spreads the first modulated data at the PHY layer to obtain first spread spectrum modulated data, and spreads the second modulated data to obtain second spread spectrum modulated data; the Beidou network device 200 sends the first spread spectrum modulated data and the first pilot information of the first spread spectrum modulated data, as well as the second spread spectrum modulated data and the second pilot information of the second spread spectrum modulated data at the PHY layer.

[0278] In a possible implementation, the method further includes: the Beidou network device 200 determining the data length of the first MDCP PDU according to the data length of the first MDCP SDU and the data length of the first physical frame.

[0279] In this way, the Beidou network device 200 can know how to split the MDCP SDU into multiple MDCP PDUs.

[0280] Some possible implementations performed by the terminal 100 are described below.

[0281] In a possible implementation, the terminal 100, at a message data convergence MDCP layer, splices M MDCP PDUs into a first message data convergence layer service data unit (MDCP SDU), including: when a second MDCP PDU received by the terminal 100 subsequently indicates that the second MDCP PDU is the last one of the M MDCP PDUs, the terminal 100, at the MDCP layer, splices the M MDCP PDUs into a first MDCP SDU, and reports the first MDCP SDU from the MDCP layer to the application layer as an application layer message.

[0282] In one possible implementation, the application layer message includes message header information and encrypted data, the message header information includes an encryption indication field and a compression indication field, the compression indication field is used to indicate the compression algorithm used by the terminal 100 when compressing the original data into compressed data, and the encryption indication field is used to indicate the encryption algorithm used by the terminal 100 when encrypting the compressed data into encrypted data; the method also includes: the terminal 100 decrypts the encrypted data in the application layer message at the application layer through the encryption algorithm indicated by the encryption indication field in the application layer message to obtain compressed data; the terminal 100 decompresses the compressed data at the application layer through the compression algorithm indicated by the compression indication field in the application layer message to obtain the original data.

[0283] In a possible implementation, the method may further include: the Beidou network device 200 splices N SLC PDUs into a first SLC SDU at the SLC layer, and reports the first SLC SDU as a first MDCP PDU from the SLC layer of the Beidou network device 200 to the MDCP layer of the Beidou network device 200; wherein, the N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes a first user ID field and a first frame type field, the first user ID field is used to indicate the terminal 100 receiving the first user frame, and the first frame type field is used to indicate the frame type of the first user frame.

[0284] In a possible implementation, the terminal 100 concatenates N SLC PDUs into a first SLC SDU at the SLC layer, and uses the first SLC SDU as the first MDCP Before the PDU is reported from the SLC layer of the Beidou network device 200 to the MDCP layer of the Beidou network device 200, the method may further include: the terminal 100 obtains the first spread spectrum modulated data sent by the terminal 100 at the PHY layer; the terminal 100 despreads the first spread spectrum modulated data at the PHY layer to obtain first modulated data and a first modulation synchronization header; the terminal 100 demodulates the first modulated data and the first modulation synchronization header at the PHY layer to obtain first pilot data and a first synchronization header; the terminal 100 removes the pilot information in the first pilot data at the PHY layer to obtain first coded data; the Beidou network device 200 decodes the first coded data at the PHY layer to obtain a first coded block physical frame and first verification information; the terminal 100 verifies the first coded block based on the first verification information at the PHY layer, and after the verification is successful, presents the first user frame in the first coded block whose ID field is the same as the terminal 100 ID as the first SLCPDU in the first SLC SDU in the SLC layer of the terminal 100 from the PHY layer to the SLC layer of the terminal 100.

[0285] In one possible implementation, the terminal 100, at the message data convergence MDCP layer, splices M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU, including: after the terminal 100, at the MDCP layer, removes the successor indication field of each MDCP PDU in the M MDCP PDUs, splicing the M MDCP PDUs into the first MDCP SDU in an order indicated by the successor indication of each MDCP PDU in the M MDCP PDUs.

[0286] The following first introduces the exemplary terminal 100 provided in the embodiment of the present application.

[0287] Figure 12 It is a structural diagram of the terminal 100 provided in an embodiment of the present application.

[0288] The following embodiments are described in detail using terminal 100 as an example. It should be understood that terminal 100 may have more or fewer components than shown in the figure, may combine two or more components, or may have a different component configuration. The various components shown in the figure may be implemented in hardware, including one or more signal processing and / or application-specific integrated circuits, software, or a combination of hardware and software.

[0289] The terminal 100 may include: a processor 110, an external memory interface 120, an internal memory 121, a universal serial bus (USB) interface 130, a charging management module 140, a power management module 141, a battery 142, an antenna 1, an antenna 2, a mobile communication module 150, a wireless communication module 160, an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, an earphone interface 170D, a sensor module 180, a button 190, a motor 191, an indicator 192, a camera 193, a display screen 194, and a subscriber identification module (SIM) card interface 195, etc. The sensor module 180 may include a pressure sensor 180A, a gyroscope sensor 180B, an air pressure sensor 180C, a magnetic sensor 180D, an acceleration sensor 180E, a distance sensor 180F, a proximity light sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, a bone conduction sensor 180M, etc.

[0290] It should be understood that the structure illustrated in the embodiments of the present invention does not constitute a specific limitation on terminal 100. In other embodiments of the present application, terminal 100 may include more or fewer components than shown, or may combine or separate certain components, or arrange the components differently. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0291] The processor 110 may include one or more processing units. For example, the processor 110 may include an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU). The different processing units may be independent devices or integrated into one or more processors.

[0292] The controller may be the nerve center and command center of the terminal 100. The controller may generate an operation control signal according to the instruction operation code and the timing signal to complete the control of fetching and executing instructions.

[0293] Processor 110 may also include a memory for storing instructions and data. In some embodiments, the memory in processor 110 is a cache memory. This memory can store instructions or data that have just been used or are being recycled by processor 110. If processor 110 needs to use the same instruction or data again, it can directly access the memory. This avoids duplicate accesses, reduces processor 110 latency, and thus improves system efficiency.

[0294] In some embodiments, the processor 110 may include one or more interfaces. The interfaces may include an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a subscriber identity module (SIM) interface, and / or a universal serial bus (USB) interface.

[0295] The I2C interface is a bidirectional synchronous serial bus that includes a serial data line (SDA) and a serial clock line (SCL). In some embodiments, the processor 110 may include multiple I2C bus lines. The processor 110 may be coupled to the touch sensor 180K, the charger, the flash, the camera 193, and the like via different I2C bus interfaces. For example, the processor 110 may be coupled to the touch sensor 180K via the I2C interface, enabling communication between the processor 110 and the touch sensor 180K via the I2C bus interface, thereby implementing the touch function of the terminal 100.

[0296] The I2S interface can be used for audio communication. In some embodiments, the processor 110 can include multiple I2S buses. The processor 110 can be coupled to the audio module 170 via the I2S bus to enable communication between the processor 110 and the audio module 170. In some embodiments, the audio module 170 can transmit audio signals to the wireless communication module 160 via the I2S interface, enabling the function of answering calls through a Bluetooth headset.

[0297] The PCM interface can also be used for audio communication, sampling, quantizing, and encoding analog signals. In some embodiments, the audio module 170 and the wireless communication module 160 can be coupled via a PCM bus interface. In some embodiments, the audio module 170 can also transmit audio signals to the wireless communication module 160 via the PCM interface, enabling the function of answering calls via a Bluetooth headset. Both the I2S interface and the PCM interface can be used for audio communication.

[0298] The UART interface is a universal serial data bus used for asynchronous communication. This bus can be a bidirectional communication bus. It converts the data to be transmitted between serial communication and parallel communication. In some embodiments, the UART interface is typically used to connect the processor 110 and the wireless communication module 160. For example, the processor 110 communicates with the Bluetooth module in the wireless communication module 160 via the UART interface to implement Bluetooth functionality. In some embodiments, the audio module 170 can transmit audio signals to the wireless communication module 160 via the UART interface, enabling the function of playing music through Bluetooth headphones.

[0299] The MIPI interface can be used to connect the processor 110 to peripheral devices such as the display 194 and the camera 193. MIPI interfaces include the camera serial interface (CSI) and the display serial interface (DSI). In some embodiments, the processor 110 and the camera 193 communicate via the CSI interface to implement the camera function of the terminal 100. The processor 110 and the display 194 communicate via the DSI interface to implement the display function of the terminal 100.

[0300] The GPIO interface can be configured via software. The GPIO interface can be configured as either a control signal or a data signal. In some embodiments, the GPIO interface can be used to connect the processor 110 to the camera 193, display 194, wireless communication module 160, audio module 170, sensor module 180, etc. The GPIO interface can also be configured as an I2C interface, an I2S interface, a UART interface, a MIPI interface, etc.

[0301] The SIM interface can be used to communicate with the SIM card interface 195 to implement the function of transmitting data to the SIM card or reading data in the SIM card.

[0302] The USB interface 130 is an interface that complies with USB standards and specifications, and may be a MiniUSB interface, a MicroUSB interface, a USB Type-C interface, or the like. The USB interface 130 can be used to connect a charger to charge the terminal 100, or to transfer data between the terminal 100 and peripheral devices. It can also be used to connect headphones to play audio. This interface can also be used to connect other electronic devices, such as AR devices.

[0303] It is understood that the interface connection relationship between the modules illustrated in the embodiment of the present invention is merely an illustrative description and does not constitute a structural limitation on the terminal 100. In other embodiments of the present application, the terminal 100 may also adopt a different interface connection method from the above embodiment, or a combination of multiple interface connection methods.

[0304] The charging management module 140 is configured to receive charging input from a charger, which may be a wireless charger or a wired charger.

[0305] The power management module 141 is used to connect the battery 142, the charging management module 140, and the processor 110. The power management module 141 receives input from the battery 142 and / or the charging management module 140 to provide power to the processor 110, the internal memory 121, the external memory, the display 194, the camera 193, and the wireless communication module 160.

[0306] The wireless communication function of the terminal 100 can be implemented through the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, the modem processor and the baseband processor.

[0307] Antenna 1 and Antenna 2 are used to transmit and receive electromagnetic wave signals. Each antenna in terminal 100 can be used to cover a single or multiple communication frequency bands. Different antennas can also be reused to improve antenna utilization. For example, antenna 1 can be reused as a diversity antenna for a wireless local area network. In other embodiments, the antennas can be used in conjunction with a tuning switch.

[0308] The mobile communication module 150 can provide solutions for wireless communications including 2G / 3G / 4G / 5G applied on the terminal 100. The mobile communication module 150 may include at least one filter, a switch, a power amplifier, a low noise amplifier (LNA), etc. The mobile communication module 150 can receive electromagnetic waves from the antenna 1, and filter, amplify, and process the received electromagnetic waves, and transmit them to the modulation and demodulation processor for demodulation. The mobile communication module 150 can also amplify the signal modulated by the modulation and demodulation processor, and convert it into electromagnetic waves for radiation through the antenna 1. In some embodiments, at least some of the functional modules of the mobile communication module 150 can be set in the processor 110. In some embodiments, at least some of the functional modules of the mobile communication module 150 can be set in the same device as at least some of the modules of the processor 110.

[0309] The modem processor may include a modulator and a demodulator. The modulator is used to modulate the low-frequency baseband signal to be transmitted into a medium-high frequency signal. The demodulator is used to demodulate the received electromagnetic wave signal into a low-frequency baseband signal. The demodulator then transmits the demodulated low-frequency baseband signal to the baseband processor for processing. After being processed by the baseband processor, the low-frequency baseband signal is passed to the application processor. The application processor outputs a sound signal through an audio device (not limited to the speaker 170A, the receiver 170B, etc.) or displays an image or video through the display screen 194. In some embodiments, the modem processor may be an independent device. In other embodiments, the modem processor may be independent of the processor 110 and be set in the same device as the mobile communication module 150 or other functional modules.

[0310] The wireless communication module 160 can provide wireless communication solutions applied on the terminal 100, including wireless local area networks (WLAN) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), frequency modulation (FM), near field communication (NFC), infrared technology (IR), Beidou communication, etc. The wireless communication module 160 can be one or more devices integrating at least one communication processing module. The wireless communication module 160 receives electromagnetic waves via the antenna 2, frequency modulates and filters the electromagnetic wave signals, and sends the processed signals to the processor 110. The wireless communication module 160 can also receive the signal to be sent from the processor 110, frequency modulate it, amplify it, and convert it into electromagnetic waves for radiation through the antenna 2.

[0311] In some embodiments, the antenna 1 of the terminal 100 is coupled to the mobile communication module 150, and the antenna 2 is coupled to the wireless communication module 160, so that the terminal 100 can communicate with the network and other devices through wireless communication technology. The wireless communication technology may include global system for mobile communications (GSM), general packet radio service (GPRS), code division multiple access (CDMA), wideband code division multiple access (WCDMA), time-division code division multiple access (TD-SCDMA), long term evolution (LTE), BT, GNSS, WLAN, NFC, FM, and / or IR technology, and Beidou communication technology. The GNSS may include a global positioning system (GPS), a global navigation satellite system (GLONASS), a Beidou navigation satellite system (BDS), a quasi-zenith satellite system (QZSS) and / or a satellite based augmentation system (SBAS).

[0312] The terminal 100 can communicate with the Beidou network device 200 via the Beidou communication technology. Optionally, the Beidou communication technology can exist in an independent chip or can be integrated into the wireless communication module 160.

[0313] Terminal 100 implements display functions through a GPU, display screen 194, and an application processor. The GPU is a microprocessor for image processing that connects display screen 194 and the application processor. The GPU is used to perform mathematical and geometric calculations for graphics rendering. Processor 110 may include one or more GPUs that execute program instructions to generate or modify display information.

[0314] Display screen 194 is used to display images, videos, and the like. Display screen 194 includes a display panel. The display panel can be a liquid crystal display (LCD), an organic light-emitting diode (OLED), an active-matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), a MiniLED, a MicroLED, a Micro-oLed, or a quantum dot light-emitting diode (QLED). In some embodiments, terminal 100 may include one or N display screens 194, where N is a positive integer greater than one.

[0315] The terminal 100 can realize the shooting function through the ISP, camera 193, video codec, GPU, display screen 194 and application processor.

[0316] The ISP processes data fed back by camera 193. For example, when taking a photo, the shutter is opened, and light is transmitted through the lens to the camera's photosensitive element. The light signal is converted into an electrical signal, which is then passed to the ISP for processing and converted into a visible image. The ISP can also perform algorithmic optimization on image noise, brightness, and skin tone. It can also optimize parameters such as exposure and color temperature of the captured scene. In some embodiments, the ISP can be located within camera 193.

[0317] The camera 193 is used to capture still images or videos. The object generates an optical image through the lens and projects it onto the photosensitive element. The photosensitive element can be a charge coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) phototransistor. The photosensitive element converts the light signal into an electrical signal, and then passes the electrical signal to the ISP for conversion into a digital image signal. The ISP outputs the digital image signal to the DSP for processing. The DSP converts the digital image signal into an image signal in a standard RGB, YUV or other format. In some embodiments, the terminal 100 may include 1 or N cameras 193, where N is a positive integer greater than 1.

[0318] The digital signal processor is used to process digital signals. In addition to processing digital image signals, it can also process other digital signals. For example, when the terminal 100 selects a frequency point, the digital signal processor is used to perform Fourier transform on the frequency point energy.

[0319] Video codecs are used to compress or decompress digital video. Terminal 100 may support one or more video codecs. This allows terminal 100 to play or record videos in various encoding formats, such as Moving Picture Experts Group (MPEG) 1, MPEG2, MPEG3, and MPEG4.

[0320] The NPU is a neural network (NN) computing processor. Drawing on the structure of biological neural networks, such as the transmission patterns between neurons in the human brain, it rapidly processes input information and can continuously self-learn. The NPU enables intelligent cognitive applications in the terminal 100, such as image recognition, face recognition, speech recognition, and text comprehension.

[0321] The internal memory 121 may include one or more random access memories (RAM) and one or more non-volatile memories (NVM).

[0322] Random access memory may include static random-access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM, for example, the fifth generation of DDR SDRAM is generally referred to as DDR5 SDRAM), etc.

[0323] Non-volatile memory may include disk storage devices and flash memory.

[0324] Flash memory can be divided into NOR FLASH, NAND FLASH, 3D NAND FLASH according to the operating principle, single-level cell (SLC), multi-level cell (MLC), triple-level cell (TLC), quad-level cell (QLC) according to the potential level of the storage cell, and universal flash storage (UFS) and embedded multi-media card (eMMC) according to the storage specification.

[0325] The random access memory can be directly read and written by the processor 110, and can be used to store executable programs (such as machine instructions) of the operating system or other running programs, and can also be used to store user and application data.

[0326] The non-volatile memory may also store executable programs and user and application data, etc., and may be loaded into the random access memory in advance for direct reading and writing by the processor 110 .

[0327] The terminal 100 can implement audio functions such as music playback and recording through the audio module 170, the speaker 170A, the receiver 170B, the microphone 170C, the headphone jack 170D, and the application processor.

[0328] The audio module 170 is used to convert digital audio information into analog audio signal output, and is also used to convert analog audio input into digital audio signals. The audio module 170 can also be used to encode and decode audio signals. In some embodiments, the audio module 170 can be provided in the processor 110, or some functional modules of the audio module 170 can be provided in the processor 110.

[0329] The speaker 170A, also called a "speaker", is used to convert audio electrical signals into sound signals. The terminal 100 can listen to music or listen to hands-free calls through the speaker 170A.

[0330] The receiver 170B, also called a "handset", is used to convert audio electrical signals into sound signals. When the terminal 100 receives a call or a voice message, the user can place the receiver 170B close to the ear to hear the voice.

[0331] Microphone 170C, also known as "microphone" or "microphone", is used to convert sound signals into electrical signals. When making a call or sending a voice message, the user can speak by putting their mouth close to the microphone 170C to input the sound signal into the microphone 170C. The terminal 100 can be provided with at least one microphone 170C. In other embodiments, the terminal 100 can be provided with two microphones 170C, which can not only collect sound signals but also realize noise reduction function. In other embodiments, the terminal 100 can also be provided with three, four or more microphones 170C to realize sound signal collection, noise reduction, and identification of sound sources, and realize directional recording function, etc.

[0332] The headphone jack 170D is used to connect a wired headphone and can be the USB interface 130 or a 3.5mm open mobile terminal platform (OMTP) standard interface or a cellular telecommunications industry association of the USA (CTIA) standard interface.

[0333] Pressure sensor 180A is used to sense pressure signals and convert them into electrical signals. In some embodiments, pressure sensor 180A can be located on display screen 194. There are many types of pressure sensors 180A, such as resistive, inductive, and capacitive. A capacitive pressure sensor can include at least two parallel plates made of conductive material. When force is applied to pressure sensor 180A, the capacitance between the electrodes changes. Terminal 100 determines the intensity of the pressure based on this change in capacitance. When a touch operation is applied to display screen 194, terminal 100 detects the touch intensity based on pressure sensor 180A. Terminal 100 can also calculate the touch location based on the detection signal from pressure sensor 180A. In some embodiments, touch operations applied to the same touch location but with different touch intensities can correspond to different operation instructions. For example, when a touch operation with an intensity less than a first pressure threshold is applied to a short message application icon, a command to view short messages is executed. When a touch operation with an intensity greater than or equal to the first pressure threshold is applied to a short message application icon, a command to create a new short message is executed.

[0334] The gyroscope sensor 180B can be used to determine the motion posture of the terminal 100. In some embodiments, the angular velocity of the terminal 100 around three axes (i.e., x, y, and z axes) can be determined by the gyroscope sensor 180B. The gyroscope sensor 180B can be used for anti-shake shooting. For example, when the shutter is pressed, the gyroscope sensor 180B detects the angle of the terminal 100 shaking, calculates the distance that the lens module needs to compensate based on the angle, and allows the lens to offset the shaking of the terminal 100 through reverse movement to achieve anti-shake. The gyroscope sensor 180B can also be used for navigation and somatosensory game scenes.

[0335] The air pressure sensor 180C is used to measure air pressure. In some embodiments, the terminal 100 calculates the altitude using the air pressure value measured by the air pressure sensor 180C to assist in positioning and navigation.

[0336] The magnetic sensor 180D includes a Hall sensor. The terminal 100 can use the magnetic sensor 180D to detect the opening and closing of the flip case. In some embodiments, when the terminal 100 is a flip phone, the terminal 100 can detect the opening and closing of the flip cover based on the magnetic sensor 180D. Furthermore, based on the detected opening and closing status of the case or flip cover, features such as automatic unlocking of the flip cover can be configured.

[0337] Accelerometer 180E can detect the magnitude of acceleration of terminal 100 in all directions (generally three axes). When terminal 100 is stationary, it can detect the magnitude and direction of gravity. It can also be used to identify the electronic device's posture, enabling applications such as switching between landscape and portrait modes and pedometers.

[0338] The distance sensor 180F is used to measure distance. The terminal 100 can measure distance using infrared or laser. In some embodiments, when shooting a scene, the terminal 100 can use the distance sensor 180F to measure distance to achieve fast focusing.

[0339] The proximity light sensor 180G may include, for example, a light emitting diode (LED) and a light detector, such as a photodiode. The light emitting diode may be an infrared light emitting diode. The terminal 100 emits infrared light outward through the light emitting diode. The terminal 100 uses the photodiode to detect infrared reflected light from nearby objects. When sufficient reflected light is detected, it can be determined that there is an object near the terminal 100. When insufficient reflected light is detected, the terminal 100 can determine that there is no object near the terminal 100. The terminal 100 can use the proximity light sensor 180G to detect when the user holds the terminal 100 close to the ear to talk, so as to automatically turn off the screen to save power. The proximity light sensor 180G can also be used in leather case mode and pocket mode to automatically unlock and lock the screen.

[0340] Ambient light sensor 180L is used to sense ambient light brightness. Terminal 100 can adaptively adjust the brightness of display screen 194 based on the perceived ambient light brightness. Ambient light sensor 180L can also be used to automatically adjust white balance when taking photos. Ambient light sensor 180L can also work with proximity light sensor 180G to detect whether terminal 100 is in a pocket to prevent accidental touches.

[0341] The fingerprint sensor 180H is used to collect fingerprints. The terminal 100 can use the collected fingerprint characteristics to implement fingerprint unlocking, access application locks, fingerprint photography, fingerprint call answering, etc.

[0342] Temperature sensor 180J is used to detect temperature. In some embodiments, terminal 100 uses the temperature detected by temperature sensor 180J to implement a temperature handling strategy. For example, when the temperature reported by temperature sensor 180J exceeds a threshold, terminal 100 reduces the performance of a processor located near temperature sensor 180J to reduce power consumption and implement thermal protection. In other embodiments, when the temperature falls below another threshold, terminal 100 heats battery 142 to prevent abnormal shutdown of terminal 100 due to low temperature. In other embodiments, when the temperature falls below yet another threshold, terminal 100 boosts the output voltage of battery 142 to prevent abnormal shutdown due to low temperature.

[0343] The touch sensor 180K is also called a "touch panel." The touch sensor 180K can be disposed on the display screen 194. The touch sensor 180K and the display screen 194 form a touch screen, also called a "touch screen." The touch sensor 180K is used to detect touch operations applied thereto or in the vicinity thereof. The touch sensor can transmit the detected touch operations to the application processor to determine the type of touch event. Visual output related to the touch operations can be provided via the display screen 194. In other embodiments, the touch sensor 180K can also be disposed on the surface of the terminal 100, in a location different from that of the display screen 194.

[0344] Keys 190 include a power button, a volume button, etc. Keys 190 may be mechanical keys or touch keys. Terminal 100 may receive key inputs and generate key signal inputs related to user settings and function control of terminal 100.

[0345] Motor 191 can generate vibration prompts. Motor 191 can be used for incoming call vibration prompts, and can also be used for touch vibration feedback. For example, touch operations acting on different applications (such as taking pictures, audio playback, etc.) can correspond to different vibration feedback effects. For touch operations acting on different areas of the display screen 194, motor 191 can also correspond to different vibration feedback effects. Different application scenarios (for example: time reminders, receiving messages, alarm clocks, games, etc.) can also correspond to different vibration feedback effects. The touch vibration feedback effect can also support customization.

[0346] The indicator 192 may be an indicator light, which may be used to indicate the charging status, power level changes, messages, missed calls, notifications, etc.

[0347] The SIM card interface 195 is used to connect a SIM card. The SIM card can be connected to and disconnected from the terminal 100 by inserting or removing it from the SIM card interface 195. The terminal 100 can support one or N SIM card interfaces, where N is a positive integer greater than one. The SIM card interface 195 can support Nano SIM cards, Micro SIM cards, SIM cards, and the like. Multiple cards can be inserted into the same SIM card interface 195 at the same time. The multiple cards can be of the same or different types. The SIM card interface 195 is also compatible with different types of SIM cards. The SIM card interface 195 is also compatible with external memory cards. The terminal 100 interacts with the network through the SIM card to implement functions such as calls and data communications.

[0348] The above content elaborates on the method provided by the present application. In order to facilitate better implementation of the above scheme of the embodiment of the present application, the embodiment of the present application also provides corresponding devices or equipment.

[0349] In the embodiment of the present application, the terminal 100 and the Beidou network device 200 can be divided into functional modules according to the above method example. For example, each functional module can be divided corresponding to each function, or two or more functions can be integrated into one processing module. The above-mentioned integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical functional division. There may be other division methods in actual implementation.

[0350] The following will be combined Figures 13 to 16 The communication device according to the embodiment of the present application is described in detail.

[0351] In the case of integrated units, see Figure 13 , Figure 131 is a schematic diagram of the structure of the communication device 1300 provided in the embodiment of the present application. The communication device 1300 may be the terminal 100 in the above embodiment. Optionally, the communication device 1300 may be a chip / chip system, for example, a Beidou communication chip. Figure 13 As shown, the communication device 1300 may include a transceiver unit 1310 and a processing unit 1320 .

[0352] In one design, the transceiver unit 1310 may be used to receive the MDCP PDU sent by the Beidou network device 200 and also to send the MDCP PDU to the Beidou network device 200 .

[0353] The processing unit 1320 may be configured to add padding data and a redundant length indication field to the first message data convergence layer service data unit MDCP SDU at the message data convergence layer MDCP layer, and then divide the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDUs.

[0354] The processing unit 1320 may be further configured to splice the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer.

[0355] Optionally, the transceiver unit 1310 may also be used to perform the above Figure 11C and Figure 11D The terminal 100 in the illustrated method embodiment performs the functional steps related to sending and receiving.

[0356] Optionally, the processing unit 1320 may also be configured to execute the above Figure 11C and Figure 11D The method embodiment shown includes the functional steps of protocol parsing and encapsulation and calculation determination performed by the terminal 100.

[0357] It should be understood that the communication device 1300 in this design can execute the method steps executed by the terminal 100 in the aforementioned embodiment. For the sake of brevity, they will not be repeated here.

[0358] In the case of integrated units, see Figure 14 , Figure 14 1 is a structural diagram of the communication device 1400 provided in an embodiment of the present application. The communication device 1400 may be the BeiDou network device 200 in the above embodiment. Optionally, the communication device 1400 may be a specific network element in the BeiDou network device 200, for example, a network element or a combination of multiple network elements in the BeiDou ground transceiver station 22, the BeiDou central station 23, and the BeiDou short message fusion communication platform 24. Figure 14 As shown, the communication device 1400 may include a transceiver unit 1410 and a processing unit 1420 .

[0359] In one design, transceiver unit 1410 may be configured to send MDCP PDUs to terminal 100 and receive MDCP PDUs sent by terminal 100.

[0360] The processing unit 1420 may be configured to divide the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDUs at the message data convergence layer MDCP layer.

[0361] Wherein, M is a positive integer; the M MDCP PDUs include a first MDCP PDU, the header information of the first MDCP PDU includes a subsequent indication field, and the subsequent indication field is used to indicate the order of the first MDCP PDU in the M MDCP PDUs; the Beidou network device 200 sends the first MDCP PDU.

[0362] In one possible implementation, M is greater than 1, the successor indication field of the first MDCP PDU is a first value, and the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a second value, and the second value is used to indicate that the first MDCP PDU is the middle MDCP PDU among the M MDCP PDUs; M is greater than 1, the successor indication field of the first MDCP PDU is a third value, and the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

[0363] In a possible implementation, M is 1, and the subsequent indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a separate MDCP PDU.

[0364] The processing unit 1420 may be further configured to concatenate the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer.

[0365] Optionally, the transceiver unit 1410 may also be used to perform the above Figure 11C and Figure 11D The Beidou network device 200 in the illustrated method embodiment performs the functional steps related to sending and receiving.

[0366] Optionally, the processing unit 1420 may also be configured to execute the above Figure 11C and Figure 11D The method embodiment shown includes the functional steps of protocol parsing and encapsulation and calculation determination performed by the Beidou network device 200.

[0367] It should be understood that the communication device 1400 in this design can execute the method steps executed by the Beidou network device 200 in the aforementioned embodiment. For the sake of brevity, they will not be repeated here.

[0368] The above describes the terminal 100 and BeiDou network device 200 of the embodiment of the present application. It should be understood that any device having the above Figure 12 Any product having the functions of the terminal 100 as described above Figure 13 Any product that implements the functions of the Beidou network device 200 falls within the protection scope of the embodiments of the present application.

[0369] As a possible product form, the terminal 100 described in the embodiment of the present application can be implemented by a general bus architecture.

[0370] See also Figure 15 , Figure 15 1 is a schematic diagram of the structure of the communication device 1500 provided in an embodiment of the present application. The communication device 1500 may be the terminal 100, or a device therein. Figure 15 As shown, the communication device 1500 includes a processor 1501 and a transceiver 1502 connected to the internal communication of the processor. The processor 1501 can be a general-purpose processor or a dedicated processor. For example, it can be a baseband processor or a central processing unit for satellite communication. The baseband processor for satellite communication can be used to process satellite communication protocols and satellite communication data, and the central processing unit can be used to control the communication device (such as a baseband chip, terminal, terminal chip, etc.), execute computer programs, and process computer program data. The transceiver 1502 can be called a transceiver unit, a transceiver, or a transceiver circuit, etc., and is used to implement transceiver functions. The transceiver 1502 can include a receiver and a transmitter. The receiver can be called a receiver or a receiving circuit, etc., and is used to implement the receiving function; the transmitter can be called a transmitter or a transmitting circuit, etc., and is used to implement the transmitting function. Optionally, the communication device 1500 can also include an antenna 1503 and / or a radio frequency unit (not shown). The antenna 1503 and / or the radio frequency unit may be located inside the communication device 1500 or may be separated from the communication device 1400 , that is, the antenna 1503 and / or the radio frequency unit may be remotely or distributedly deployed.

[0371] Optionally, the communication device 1500 may include one or more memories 1504, on which instructions may be stored. The instructions may be computer programs. The computer programs may be executed on the communication device 1500 to enable the communication device 1500 to perform the methods described in the above method embodiments. Optionally, the memories 1504 may also store data. The communication device 1500 and the memories 1504 may be provided separately or integrated together.

[0372] The processor 1501 , the transceiver 1502 , and the memory 1504 may be connected via a communication bus.

[0373] In one design, the communication device 1500 may be configured to perform the functions of the terminal 100 in the aforementioned embodiment: the processor 1501 may be configured to perform the aforementioned Figure 11C and Figure 11D In the embodiment shown, the terminal 100 performs the protocol parsing and encapsulation and the functional steps determined by the operation and / or other processes used in the technology described herein; the transceiver 1502 can be used to perform the above Figure 11C and Figure 11D The terminal 100 in the illustrated embodiment performs functional steps related to protocol parsing and encapsulation and computational determination and / or other processes for the technology described herein.

[0374] In any of the above designs, processor 1501 may include a transceiver for implementing receiving and transmitting functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing the receiving and transmitting functions may be separate or integrated. The transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or the transceiver circuit, interface, or interface circuit may be used for transmitting or delivering signals.

[0375] In any of the above designs, processor 1501 may store instructions, which may be computer programs. The computer programs, when executed on processor 1501, may cause communication device 1500 to execute the method steps performed by terminal 100 in the above method embodiments. The computer programs may be fixed in processor 1501, in which case processor 1501 may be implemented by hardware.

[0376] In one implementation, the communication device 1500 may include a circuit that can implement the functions of sending, receiving, or communicating in the aforementioned method embodiments. The processor and transceiver described in this application can be implemented on an integrated circuit (IC), an analog IC, a radio frequency integrated circuit RFIC, a mixed signal IC, an application specific integrated circuit (ASIC), a printed circuit board (PCB), an electronic device, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal oxide semiconductor (CMOS), N-type metal oxide semiconductor (nMetal-oxide-semiconductor, NMOS), P-type metal oxide semiconductor (positive channel metal oxide semiconductor, PMOS), bipolar junction transistor (bipolar junction transistor, BJT), bipolar CMOS (BiCMOS), silicon germanium (SiGe), gallium arsenide (GaAs), etc.

[0377] The scope of the communication device described in this application is not limited thereto, and the structure of the communication device may not be limited thereto. Figure 15 The communication device 1500 may be a standalone device or may be part of a larger device. For example, the communication device 1500 may be:

[0378] (1) An independent integrated circuit (IC), or chip, or chip system or subsystem;

[0379] (2) a collection of one or more ICs, optionally including a storage component for storing data and computer programs;

[0380] (3) ASIC, such as modem;

[0381] (4) Modules that can be embedded in other devices;

[0382] (5) Receivers, terminals, smart terminals, cellular phones, wireless devices, handheld devices, mobile units, vehicle-mounted devices, network devices, cloud devices, artificial intelligence devices, etc.;

[0383] (6)Others, etc.

[0384] As a possible product form, any network element in the Beidou network device 200 described in the embodiment of the present application (for example, the Beidou ground transceiver station 22, the Beidou central station 23, the Beidou short message fusion communication platform 24) can be implemented by a general bus architecture.

[0385] See also Figure 16 , Figure 16 1 is a schematic diagram of the structure of the communication device 1600 provided in the embodiment of the present application. The communication device 1600 may be the Beidou network device 200, or a device therein. Figure 16 As shown, the communication device 1600 includes a processor 1601 and a transceiver 1602 connected to the internal communication of the processor. The processor 1601 is a general-purpose processor or a dedicated processor. For example, it can be a baseband processor or a central processing unit for satellite communication. The baseband processor for satellite communication can be used to process satellite communication protocols and satellite communication data, and the central processing unit can be used to control the communication device (such as a baseband chip, etc.), execute computer programs, and process computer program data. The transceiver 1602 can be called a transceiver unit, a transceiver, or a transceiver circuit, etc., for implementing transceiver functions. The transceiver 1602 can include a receiver and a transmitter. The receiver can be called a receiver or a receiving circuit, etc., for implementing a receiving function; the transmitter can be called a transmitter or a transmitting circuit, etc., for implementing a transmitting function. Optionally, the communication device 1600 can also include an antenna 1603 and / or a radio frequency unit (not shown). The antenna 1603 and / or the radio frequency unit may be located inside the communication device 1600 or may be separated from the communication device 1600 , that is, the antenna 1603 and / or the radio frequency unit may be remotely or distributedly deployed.

[0386] Optionally, the communication device 1600 may include one or more memories 1604, on which instructions may be stored. The instructions may be computer programs. The computer programs may be executed on the communication device 1600 to enable the communication device 1600 to perform the methods described in the above method embodiments. Optionally, the memories 1604 may also store data. The communication device 1600 and the memories 1604 may be provided separately or integrated together.

[0387] The processor 1601 , the transceiver 1602 , and the memory 1604 may be connected via a communication bus.

[0388] In one design, the communication device 1600 can be used to perform the functions of the Beidou network device 200 in the above embodiment: the processor 1601 can be used to perform the above Figure 11C and Figure 11DIn the embodiment shown, the Beidou network device 200 performs the protocol parsing and encapsulation and the functional steps determined by the operation and / or other processes used in the technology described herein; the transceiver 1602 can be used to perform the above Figure 11C and Figure 11D The Beidou network device 200 in the illustrated embodiment performs functional steps related to protocol parsing and encapsulation and computational determination and / or other processes for the technology described herein.

[0389] In any of the above designs, processor 1601 may include a transceiver for implementing receiving and transmitting functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing the receiving and transmitting functions may be separate or integrated. The transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or the transceiver circuit, interface, or interface circuit may be used for transmitting or delivering signals.

[0390] In any of the above designs, processor 1601 may store instructions, which may be computer programs. The computer programs, when executed on processor 1601, may cause communication device 1600 to execute the method steps performed by terminal 100 in the above method embodiments. The computer programs may be fixed in processor 1601, in which case processor 1601 may be implemented by hardware.

[0391] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program code is stored. When the processor executes the computer program code, the communication device executes the method in any of the aforementioned embodiments.

[0392] An embodiment of the present application further provides a computer program product, which, when executed on a computer, enables the computer to execute the method in any of the aforementioned embodiments.

[0393] An embodiment of the present application also provides a communication device, which can exist in the form of a chip product. The structure of the device includes a processor and an interface circuit. The processor is used to communicate with other devices through a receiving circuit, so that the device executes the method in any of the aforementioned embodiments.

[0394] An embodiment of the present application further provides a Beidou communication system, including a terminal 100 and a Beidou network device 200. The terminal 100 and the Beidou network device 200 can execute the method in any of the aforementioned embodiments.

[0395] This application describes the short message communication function of the Beidou communication system. It is understood that other satellite systems may also support short message communication functions. Therefore, the method described in this application is not limited to the Beidou communication system. If other satellite systems also support short message communication functions, the method described in this application is also applicable to communications in other satellite systems.

[0396] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0397] As used in the above embodiments, the term “when…” may be interpreted to mean “if…” or “after…” or “in response to determining…” or “in response to detecting…”, depending on the context. Similarly, the phrases “upon determining…” or “if (stated condition or event) is detected” may be interpreted to mean “if determining…” or “in response to determining…” or “upon detecting (stated condition or event)” or “in response to detecting (stated condition or event)”, depending on the context.

[0398] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part 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, the process or function described in the embodiment of the present application is generated in whole or in part. 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 computer-readable storage medium. 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 a wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrations. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk).

[0399] Those skilled in the art will appreciate that all or part of the process steps in the above-described method embodiments can be implemented by a computer program instructing the relevant hardware. The program can be stored in a computer-readable storage medium, and when executed, the program can include the process steps in the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM or random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A data transmission control method in a satellite communication system, characterized in that: include: After adding padding data and a redundant length indication field to the first message data convergence layer service data unit (MDCP SDU) at the message data convergence layer (MDCP) SDU, the terminal divides the first message data convergence layer service data unit (MDCP SDU) into M data convergence layer protocol data units (MDCP PDUs), where M is a positive integer; wherein the redundant length indication field is used to indicate the data length of the padding data; the M MDCP PDUs include a first MDCP PDU; the header information of the first MDCP PDU includes a subsequent indication field; and the subsequent indication field is used to indicate the order of the first MDCP PDU in the M MDCP PDUs. The terminal sends the first MDCP PDU to the satellite network device.

2. The method according to claim 1, characterized in that M is greater than 1, and a successor indication field of the first MDCP PDU is a first value, where the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a second value, where the second value is used to indicate that the first MDCP PDU is a middle MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a third value, where the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

3. The method according to any one of claims 1 or 2, characterized in that The M is 1, and the successor indication field of the first MDCP PDU is a fourth value, where the fourth value is used to indicate that the first MDCP PDU is a single MDCP PDU.

4. The method according to claim 3, characterized in that The terminal adds padding data and redundant length indication fields to the first message data convergence layer service data unit MDCP SDU at the message data convergence layer MDCP layer, and then divides the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDU, specifically including: The terminal generates an application layer message at the application layer; The terminal uses the application layer message as the first MDCP SDU at the MDCP layer, and after adding padding data and a redundant length indication field to the first MDCP SDU, divides the first MDCP SDU into the M MDCP PDUs.

5. The method according to claim 4, characterized in that The terminal uses the application layer message as the first MDCP SDU at the MDCP layer, and before dividing the first MDCP SDU into the M MDCP PDUs after adding padding data and a redundant length indication field. The terminal obtains original data; The terminal compresses the original data at the application layer to obtain compressed data; The terminal encrypts the compressed data at the application layer to obtain encrypted data; The terminal adds message header information to the encrypted data header to obtain the application layer message; wherein the message header information includes a compression indication field and an encryption indication field, the compression indication field is used to indicate the compression algorithm used when compressing the original data, and the encryption indication field is used to indicate the encryption algorithm used when encrypting the compressed data.

6. The method according to claim 5, characterized in that The terminal sending the first MDCP PDU to the satellite network device specifically includes: The terminal transmits the first MDCP PDU to a satellite link control SLC layer as a first satellite link control layer service data unit SLC SDU of the SLC layer; The terminal divides the first SLC SDU into N satellite link control layer protocol data units (SLCPDUs) at the SLC layer, where N is a positive integer; wherein the N SLC PDUs include a first SLC PDU, and frame header information of the first SLC PDU includes a service data unit alternation indication (SAI) field, a total number of frames field, and a frame sequence number field; the SAI field is used to indicate whether the first SLC PDU is retransmitted data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate a frame sequence number of the first SLC PDU in the first SLC SDU; The terminal sends the first SLC PDU to the satellite network device.

7. The method according to claim 6, characterized in that The terminal sending the first SLC PDU to the satellite network device specifically includes: The terminal sends the first SLC PDU from the SLC layer to the physical PHY layer as a first coding block of the PHY layer; The terminal adds check bit information at the end of the first coding block at the PHY layer, and encodes the first coding block and the check bit information to obtain first coded data; The terminal inserts pilot information into the first coded data at the PHY layer to obtain first pilot data; The terminal modulates the first pilot data and the synchronization header of the first pilot data at the PHY layer to obtain first modulated data and a first modulated synchronization header; The terminal performs spectrum spreading on the first modulated data and the modulation synchronization header at the PHY layer to obtain first spread spectrum modulated data; The terminal sends the first spread spectrum modulated data as a first physical frame to the satellite network device at the PHY layer.

8. The method according to any one of claims 4 to 7, characterized in that: The method further comprises: The terminal determines the data length of the first MDCP PDU according to the data length of the first MDCP SDU and the data length of the first physical frame.

9. A data transmission control method in a satellite communication system, characterized in that: include: The satellite network device receives M data convergence layer protocol data units (MDCP PDUs) sent by the terminal, where M is a positive integer; wherein the M MDCP PDUs include a first MDCP PDU, and header information of the first MDCP PDU includes a subsequent indication field, where the subsequent indication field is used to indicate an order of the first MDCP PDU in the M MDCP PDUs; The satellite network device splices the M MDCP PDUs at a message data convergence MDCP layer, and removes a redundant length indication field and padding data after splicing to obtain a first message data convergence layer service data unit MDCP SDU, where the redundant length indication field is used to indicate a data length of the padding data.

10. The method according to claim 9, characterized in that M is greater than 1, and a successor indication field of the first MDCP PDU is a first value, where the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a second value, where the second value is used to indicate that the first MDCP PDU is a middle MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a third value, where the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

11. The method according to claim 9 or 10, characterized in that The successor indication field of the first MDCP PDU is a fourth value, and the fourth value is used to indicate that the first MDCP PDU is a single MDCP PDU.

12. The method according to claim 11, characterized in that The satellite network device splices the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: When a second MDCP PDU received by the satellite network device subsequently indicates that the second MDCP PDU is the last one of the M MDCP PDUs, the satellite network device concatenates the M MDCP PDUs into a first MDCP SDU at the MDCP layer, and reports the first MDCP SDU from the MDCP layer to the application layer as an application layer message.

13. The method according to claim 12, characterized in that The application layer message includes message header information and encrypted data, the message header information includes an encryption indication field and a compression indication field, the compression indication field is used to indicate the compression algorithm used by the terminal when compressing original data into compressed data, and the encryption indication field is used to indicate the encryption algorithm used by the terminal when encrypting the compressed data into encrypted data; The method further comprises: The satellite network device decrypts the encrypted data in the application layer message at the application layer using an encryption algorithm indicated by an encryption indication field in the application layer message to obtain the compressed data; The satellite network device decompresses the compressed data at the application layer using a compression algorithm indicated by a compression indication field in the application layer message to obtain the original data.

14. The method according to claim 13, characterized in that The method further comprises: The satellite network device splices N SLC PDUs into a first SLC SDU at the SLC layer, and reports the first SLC SDU as the first MDCP PDU from the SLC layer of the satellite network device to the MDCP layer of the satellite network device; wherein the N SLC PDUs include a first SLC PDU, and the frame header information of the first SLC PDU includes a service data unit alternation indication SAI field, a total number of frames field, and a frame sequence number field; the SAI field is used to indicate whether the first SLC PDU is retransmitted data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU.

15. The method according to claim 14, characterized in that Before the satellite network device, at the SLC layer, splices the N SLC PDUs into the first SLC SDU and reports the first SLC SDU as the first MDCP PDU from the SLC layer of the satellite network device to the MDCP layer of the satellite network device, the method further includes: The satellite network device obtains the first spread spectrum modulated data sent by the terminal at the physical PHY layer; The satellite network device despreads the first spread spectrum modulated data at the PHY layer to obtain first modulated data and a first modulation synchronization header; The satellite network device demodulates the first modulated data and the first modulated synchronization header at the PHY layer to obtain first pilot data and a first synchronization header; The satellite network device removes the pilot information in the first pilot data at the PHY layer to obtain first coded data; The satellite network device decodes the first coded data at the PHY layer to obtain a first coded block and first verification information; The satellite network device verifies the first coding block based on the first verification information at the PHY layer, and after the verification is successful, presents the first coding block from the PHY layer to the SLC layer of the satellite network device as the first SLC PDU in the first SLC SDU in the SLC layer of the satellite network device.

16. The method according to any one of claims 9 to 15, characterized in that The satellite network device splices the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the MDCP layer, including: After removing the successor indication field of each MDCP PDU in the M MDCP PDUs at the MDCP layer, the satellite network device splices the M MDCP PDUs into a first MDCP SDU in an order indicated by the successor indication of each MDCP PDU in the M MDCP PDUs.

17. A data transmission control method in a satellite communication system, characterized in that: include: The satellite network device divides the first message data convergence layer service data unit (MDCP SDU) into M data convergence layer protocol data units (MDCP PDUs) at the message data convergence layer (MDCP), where M is a positive integer; wherein the M MDCP PDUs include a first MDCP PDU, and header information of the first MDCP PDU includes a subsequent indication field, where the subsequent indication field is used to indicate an order of the first MDCP PDU in the M MDCP PDUs; The satellite network device transmits the first MDCP PDU to a satellite link control SLC layer as a first satellite link control layer service data unit SLC SDU of the SLC layer; The satellite network device divides the first SLC SDU into N satellite link control layer protocol data units (SLC PDUs) at the SLC layer, where N is a positive integer; wherein the N SLC PDUs include a first SLC PDU, and frame header information of the first SLC PDU includes a first user ID field and a first frame type field, wherein the first user ID field is used to indicate a terminal receiving the first user frame, and the first frame type field is used to indicate a frame type of the first user frame; The satellite network device sends the first SLC PDU.

18. The method according to claim 17, characterized in that M is greater than 1, and a successor indication field of the first MDCP PDU is a first value, where the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a second value, where the second value is used to indicate that the first MDCP PDU is a middle MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a third value, where the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

19. The method according to any one of claims 17 or 18, characterized in that The M is 1, the successor indication field of the first MDCP PDU is a fourth value, and the fourth value is used to indicate that the first MDCP PDU is a single MDCP PDU.

20. The method according to any one of claims 17 to 19, characterized in that: The satellite network device divides the first message data convergence layer service data unit MDCP SDU into M data convergence layer protocol data units MDCP PDU at the message data convergence MDCP layer, specifically including: The satellite network device generates an application layer message at the application layer; The satellite network device uses the application layer message as a first MDCP SDU at the MDCP layer, and divides the first MDCP SDU into M MDCP PDUs.

21. The method according to claim 20, characterized in that The satellite network device generates an application layer message at the application layer, specifically including: The satellite network device acquires raw data; The satellite network device compresses the original data at the application layer to obtain compressed data; The satellite network device encrypts the compressed data at the application layer to obtain encrypted data; The satellite network device adds message header information to the encrypted data header to obtain the application layer message; wherein the message header information includes a compression indication field and an encryption indication field, the compression indication field is used to indicate the compression algorithm used when compressing the original data, and the encryption indication field is used to indicate the encryption algorithm used when encrypting the compressed data.

22. The method according to claim 21, characterized in that The N SLC PDUs further include a second SLC PDU, and the satellite network device sends the first SLC PDU to the terminal, including: The satellite network device sends the first SLC PDU and the second SLC PDU to the physical PHY layer; The satellite network device generates a first physical frame from the first SLC PDU and generates a second physical frame from the second SLC PDU at the PHY layer; The satellite network device sends the first physical frame and the second physical frame.

23. The method according to claim 22, characterized in that The satellite network device sending the first physical frame and the second physical frame includes: The satellite network device adds first check bit information to the end of the first physical frame at the PHY layer, and encodes the first physical frame and the first check bit information to obtain first encoded data; adds second check bit information to the end of the second physical frame, and encodes the second physical frame and the second check bit information to obtain second encoded data; The satellite network device modulates the first coded data and the first reserved field of the first coded data at the PHY layer to obtain first modulated data, and modulates the second coded data and the second reserved field of the second coded data to obtain second modulated data; The satellite network device performs spectrum spreading on the first modulated data at the PHY layer to obtain first spread spectrum modulated data, and performs spectrum spreading on the second modulated data to obtain second spread spectrum modulated data; The satellite network device transmits the first spread spectrum modulation data and first pilot information of the first spread spectrum modulation data, and the second spread spectrum modulation data and second pilot information of the second spread spectrum modulation data at the PHY layer.

24. The method according to any one of claims 19 to 23, characterized in that The method further comprises: The satellite network device determines the data length of the first MDCP PDU according to the data length of the first MDCP SDU and the data length of the first physical frame.

25. A data transmission control method in a satellite communication system, characterized in that: include: The terminal receives N satellite link control layer protocol data units (SLC PDUs) sent by the satellite network device; The terminal splices the N SLC PDUs into a first satellite link control layer service data unit (SLCSDU) at the SLC layer, and reports the first SLC SDU as a first data convergence layer protocol data unit (MDCP PDU) from the SLC layer of the satellite network device to a message data convergence (MDCP) layer of the satellite network device; wherein the N SLC PDUs include a first SLC PDU, and frame header information of the first SLC PDU includes a first user ID field and a first frame type field, the first user ID field is used to indicate a terminal receiving the first user frame, and the first frame type field is used to indicate a frame type of the first user frame; The terminal splices, at the MDCP layer, M MDCP PDUs into a first message data convergence layer service data unit (MDCP SDU), wherein the M MDCP PDUs include the first MDCP PDU, and header information of the first MDCP PDU includes a successor indication field, where the successor indication field is used to indicate an order of the first MDCP PDU in the M MDCP PDUs.

26. The method according to claim 25, characterized in that M is greater than 1, and a successor indication field of the first MDCP PDU is a first value, where the first value is used to indicate that the first MDCP PDU is the first MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a second value, where the second value is used to indicate that the first MDCP PDU is a middle MDCP PDU among the M MDCP PDUs; The M is greater than 1, and the successor indication field of the first MDCP PDU is a third value, where the third value is used to indicate that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs.

27. The method according to claim 25 or 26, characterized in that The successor indication field of the first MDCP PDU is a fourth value, and the fourth value is used to indicate that the first MDCP PDU is a single MDCP PDU.

28. The method according to claim 27, characterized in that The terminal splices the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: When a subsequent indication in a second MDCP PDU received by the terminal indicates that the second MDCP PDU is the last one of the M MDCP PDUs, the terminal concatenates the M MDCP PDUs into a first MDCP SDU at the MDCP layer, and reports the first MDCP SDU from the MDCP layer to the application layer as an application layer message.

29. The method according to claim 28, characterized in that The application layer message includes message header information and encrypted data, the message header information includes an encryption indication field and a compression indication field, the compression indication field is used to indicate the compression algorithm used by the terminal when compressing original data into compressed data, and the encryption indication field is used to indicate the encryption algorithm used by the terminal when encrypting the compressed data into encrypted data; The method further comprises: The terminal decrypts the encrypted data in the application layer message at the application layer using an encryption algorithm indicated by an encryption indication field in the application layer message to obtain the compressed data; The terminal decompresses the compressed data at the application layer using a compression algorithm indicated by a compression indication field in the application layer message to obtain the original data.

30. The method according to claim 29, wherein Before the terminal, at the SLC layer, splices the N SLC PDUs into the first SLC SDU, and reports the first SLC SDU as the first MDCP PDU from the SLC layer of the satellite network device to the MDCP layer of the satellite network device, the method further includes: The terminal obtains first spread spectrum modulated data sent by the terminal at a physical PHY layer; The terminal despreads the first spread spectrum modulated data at the PHY layer to obtain first modulated data and a first modulation synchronization header; The terminal demodulates the first modulated data and the first modulated synchronization header at the PHY layer to obtain first pilot data and a first synchronization header; The terminal removes the pilot information in the first pilot data at the PHY layer to obtain first coded data; The satellite network device decodes the first coded data at the PHY layer to obtain a first coded block physical frame and first check information; The terminal verifies the first coding block based on the first verification information at the PHY layer, and after the verification is successful, presents the first user frame in the first coding block whose ID field is the same as the terminal ID as the first SLC PDU in the first SLC SDU in the SLC layer of the terminal from the PHY layer to the SLC layer of the terminal.

31. The method according to any one of claims 28 to 30, characterized in that The terminal splices the M MDCP PDUs into a first message data convergence layer service data unit MDCP SDU at the message data convergence MDCP layer, including: After removing the successor indication field of each MDCP PDU in the M MDCP PDUs at the MDCP layer, the terminal concatenates the M MDCP PDUs into a first MDCP SDU according to the order indicated by the successor indication field of each MDCP PDU in the M MDCP PDUs.

32. A satellite communication system, characterized in that: It comprises a satellite network device and a terminal; wherein: the terminal is used to execute a data transmission control method in a satellite communication system as described in any one of claims 1-8 and / or claims 25-31; the satellite network device is used to execute a data transmission control method in a satellite communication system as described in any one of claims 9-16 and / or claims 17-24.

33. A communication device, characterized in that: The invention comprises one or more processors, one or more memories and a transceiver; wherein the transceiver and the one or more memories are coupled to the one or more processors, the one or more memories are used to store computer program code, and the computer program code includes computer instructions. When the one or more processors execute the computer instructions, the communication device executes a data transmission control method in a satellite communication system as described in any one of claims 9 to 16 and / or claims 17 to 24.

34. The communication device according to claim 33, wherein: The communication device is a satellite network device.

35. A communication device, characterized in that: The device comprises one or more processors, one or more memories, and a transceiver; wherein the transceiver and the one or more memories are coupled to the one or more processors, the one or more memories are used to store computer program code, and the computer program code includes computer instructions. When the one or more processors execute the computer instructions, the communication device executes a data transmission control method in a satellite communication system as described in any one of claims 1 to 8 and / or claims 25 to 31.

36. The communication device according to claim 35, characterized in that The communication device is a terminal.

37. A computer-readable storage medium storing instructions, which, when executed on a computer, causes the computer to execute a method for controlling data transmission in a satellite communication system according to any one of claims 9 to 16 and / or claims 17 to 24.

38. A computer-readable storage medium storing instructions, which, when executed on a computer, causes the computer to execute a method for controlling data transmission in a satellite communication system according to any one of claims 1 to 8 and / or claims 25 to 31.

39. A chip or chip system, applied to a terminal, characterized in that: The method comprises a processing circuit and an interface circuit, wherein the interface circuit is used to receive code instructions and transmit them to the processing circuit, and the processing circuit is used to run the code instructions to execute a data transmission control method in a satellite communication system as claimed in any one of claims 1 to 8 and / or claims 25 to 31.

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