WO2023011377A1 - 一种北斗通信系统中应用层回执传输方法、系统及装置 - Google Patents

一种北斗通信系统中应用层回执传输方法、系统及装置 Download PDF

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Publication number
WO2023011377A1
WO2023011377A1 PCT/CN2022/109263 CN2022109263W WO2023011377A1 WO 2023011377 A1 WO2023011377 A1 WO 2023011377A1 CN 2022109263 W CN2022109263 W CN 2022109263W WO 2023011377 A1 WO2023011377 A1 WO 2023011377A1
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Prior art keywords
slc
application layer
mdcp
network device
terminal
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PCT/CN2022/109263
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English (en)
French (fr)
Inventor
朱颖
李振洲
钱锋
甘雯昱
朱旭东
姚振东
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华为技术有限公司
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Priority to EP22852090.4A priority Critical patent/EP4354759A1/en
Publication of WO2023011377A1 publication Critical patent/WO2023011377A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/30—Definitions, standards or architectural aspects of layered protocol stacks
    • H04L69/32—Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
    • H04L69/322—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions
    • H04L69/324—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions in the data link layer [OSI layer 2], e.g. HDLC
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/1851—Systems using a satellite or space-based relay
    • H04B7/18513—Transmission in a satellite or space-based system
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
    • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
    • H04L1/1607—Details of the supervisory signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/04—Protocols for data compression, e.g. ROHC
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/30—Definitions, standards or architectural aspects of layered protocol stacks
    • H04L69/32—Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
    • H04L69/322—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions
    • H04L69/326—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions in the transport layer [OSI layer 4]

Definitions

  • the present application relates to the field of satellite communication, in particular to a method, system and device for transmitting application layer receipts in the Beidou communication system.
  • the Beidou satellite navigation system is a major infrastructure integrating positioning, timing and communication.
  • the Beidou short message communication service is one of the characteristics of the Beidou satellite navigation system that distinguishes it from other global navigation systems such as GPS, GLONASS, and GALILEO.
  • the Beidou short message communication service is especially suitable for communication in areas where mobile communication is not covered, or cannot be covered, or the communication system is damaged, such as oceans, deserts, grasslands, and uninhabited areas.
  • the short message system of the Beidou-3 satellite has upgraded the short message technical system and opened some necessary resources of the communication system of the Beidou short message service to civilian use. According to the civilian business and equipment characteristics, it needs to be based on the Beidou short message service.
  • the characteristics of the communication system design the communication protocol.
  • the communication system of the Beidou short message service adopts a satellite link control layer (satellite link control protocol, SLC) feedback mechanism to ensure that the transmitted data packets are not lost. That is, the receiving device can send an acknowledgment character (acknowledge character, ACK) of the SLC layer to the sending device when the receiving window ends, and the sending device can determine the receiving device's data packet reception situation at the SLC layer based on the ACK. The sending device may retransmit the data when it determines that the receiving device did not receive a complete data packet. However, this can only ensure that the sending device can confirm that the receiving device receives the data packet at the SLC layer, but cannot confirm the situation that the data packet is parsed at the application layer.
  • SLC satellite link control layer
  • This application provides an application layer receipt transmission method, system and related devices in the Beidou communication system, which realizes the establishment of a credible message transmission mechanism between the sending device and the receiving device, and ensures that the receiving device can parse the application layer message to obtain Raw data, ensuring normal communication between sending and receiving devices.
  • the present application provides an application layer receipt transmission method in the Beidou communication system, including:
  • the sending device sends the first message data convergence layer protocol data unit MDCP PDU in the first application layer message to the receiving device.
  • the header information of the first MDCP PDU includes a successor indication field.
  • the successor indication field is used to indicate the order of the first MDCP PDU in the first application layer message.
  • the sending device receives the first application layer receipt information sent by the receiving device.
  • the first application layer receipt information is used to indicate the result of parsing the first application layer packet by the receiving device.
  • the receiving device can generate application layer receipt information based on the result of parsing the application layer message after obtaining the application layer message sent by the sending device.
  • the receiving device can send the application layer receipt information to the sending device, and the sending device can determine the situation of the receiving device parsing the application layer message based on the application layer receipt information.
  • the sending device can confirm whether the receiving device has obtained the original data of the sending device.
  • the sending device can be clear about the sending of the data.
  • the sending device sends the first MDCP PDU in the first application layer message to the receiving device, specifically including:
  • the sending device uses the first MDCP PDU as the first satellite link control layer service data unit SLC SDU of the SLC layer of the sending device, and sends it from the MDCP layer of the sending device to the SLC layer of the sending device.
  • the sending device splits the first SLC SDU into N SLC PDUs at the SLC layer of the sending device, where N is a positive integer.
  • the N SLC PDUs include the first SLC PDU
  • the frame header information of the first SLC PDU includes the frame total number field and the frame sequence number field.
  • the frame total number field is used to indicate the total number N of SLC PDUs included in the first SLC SDU
  • the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU.
  • the sending device sends N SLC PDUs to the receiving device.
  • the sending device sends the first MDCP PDU to the SLC layer as the first SLC SDU of the SLC layer and splits the first SLC SDU into N SCL PDUs.
  • the embodiment shown in FIG. 7 can be referred to. This will not be repeated here.
  • the first application layer receipt information is also used to indicate that the receiving device has received all the N SLC PDUs in the first SLC SDU.
  • the sending device can determine all the SLC PDUs corresponding to the application layer message received by the receiving device through the first application layer receipt information.
  • the method before the sending device receives the first application layer receipt information sent by the receiving device, the method further includes: the sending device receives a first confirmation character ACK sent by the receiving device.
  • the first ACK is used to indicate that the receiving device has received all the N SLC PDUs in the first SLC SDU.
  • the method before the sending device receives the first application layer receipt information sent by the receiving device, the method further includes: the sending device receives a second confirmation character ACK sent by the receiving device.
  • the second ACK is used to indicate the frame sequence number of the SLC PDU not received by the receiving device in the first SLC SDU.
  • the sending device retransmits the SLC PDUs not received by the receiving device in the first SLC SDU to the receiving device.
  • the method before the sending device receives the first confirmation character ACK sent by the receiving device, the method further includes: the sending device receives the second confirmation character ACK sent by the receiving device.
  • the second ACK is used to indicate the frame sequence number of the SLC PDU not received by the receiving device in the first SLC SDU.
  • the sending device retransmits the SLC PDUs not received by the receiving device in the first SLC SDU to the receiving device.
  • the sending device sends N SLC PDUs to the receiving device, which specifically includes: the sending device sends the first SLC PDU from the SLC layer of the sending device to the physical PHY layer as the PHY layer of the sending device Layer's first user frame.
  • the sending device performs physical layer processing on the first user frame to obtain first inbound data.
  • the sending device sends first inbound data to the receiving device.
  • the method before the sending device sends the first MDCP PDU in the first application layer message to the receiving device, the method further includes: the sending device obtains the application layer sent by the sending device at the message data aggregation MDCP layer. The first application layer packet.
  • the sending device takes the first application layer message as an MDCP SDU at the MDCP layer, and splits the MDCP SDU into M MDCP PDUs.
  • M is a positive integer.
  • the M MDCP PDUs include the first MDCP PDU.
  • the method further includes: the sending device sends M MDCP PDUs from the MDCP layer to the SLC layer as M SLC SDUs of the SLC layer, and the M SLC SDUs include the first SLC SDU.
  • the method before the sending device acquires at the MDCP layer the first application layer message delivered by the application layer of the sending device, the method further includes: the sending device acquires original data.
  • the sending device encodes and compresses the original data at the application layer to obtain the first compressed data.
  • the sending device encrypts the first compressed data at the application layer to obtain the first encrypted data.
  • the sending device adds message header information to the first encrypted data header to obtain the first application layer message.
  • the message header information includes a compression indication field and an encryption indication field
  • the compression indication field is used to indicate the encoding compression algorithm used when compressing the original data
  • the encryption indication field is used to indicate the encryption algorithm used when encrypting the first compressed data.
  • the method further includes:
  • the sending device determines that the receiving device fails to parse the first application layer message based on the first application layer receipt information, and the sending device retransmits the first application layer message to the receiving device.
  • the sending device determines that the receiving device fails to parse the application layer message, it can send the application layer message again, so as to avoid the situation that the receiving device fails to parse the application layer message due to data errors during transmission.
  • the first application layer receipt information includes a first parsing result, where the first parsing result is used to indicate that the receiving device fails to decrypt the first application layer packet.
  • the sending device negotiates key information with the receiving device.
  • the sending device encrypts the first compressed data based on the negotiated key information to obtain the second encrypted data.
  • the sending device sends the second application layer message including the second encrypted data to the receiving device.
  • the first application layer receipt information includes a second parsing result, where the second parsing result is used to indicate that the receiving device fails to decode and decompress the application layer packet.
  • the sending device negotiates a codebook with the receiving device based on the second parsing result.
  • the sending device encodes and compresses the original data based on the negotiated codebook to obtain second compressed data.
  • the sending device encrypts the second compressed data to obtain third encrypted data.
  • the sending device sends the third application layer packet to the receiving device, where the third application layer packet includes third encrypted data.
  • the above-mentioned sending device is a terminal
  • the receiving device is a Beidou network device.
  • the sending device is a Beidou network device
  • the receiving device is a terminal.
  • the present application provides a method for transmitting application layer receipts in the Beidou communication system, including:
  • the receiving device receives the first MDCP PDU of the first application layer message sent by the sending device.
  • the header information of the first MDCP PDU includes a successor indication field.
  • the successor indication field is used to indicate the order of the first MDCP PDU in the first application layer message.
  • the receiving device After the receiving device determines that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs in the first application layer message, the receiving device obtains the first application layer message based on the first MDCP PDU.
  • M is a positive integer.
  • the receiving device generates first application layer receipt information, where the first application layer receipt information is used to indicate a result of parsing the first application layer message by the receiving device.
  • the receiving device sends the first application layer receipt information to the sending device.
  • the method before the receiving device generates the first application layer receipt information, the method further includes: the receiving device decrypts the first encrypted data in the first application layer message, and obtains the First compress the data.
  • the method further includes: the receiving device decrypts the first The compressed data is decoded and decompressed to obtain the original data.
  • the method before the receiving device generates the first application layer receipt information, the method further includes: the receiving device fails to decrypt the first encrypted data.
  • the receiving device generates first application layer receipt information.
  • the first application layer receipt information includes a first parsing result, and the first parsing result is used to indicate that the receiving device fails to decrypt.
  • the method before the receiving device generates the first application layer receipt information, the method further includes: the receiving device fails to decode and decompress the first compressed data.
  • the receiving device generates first application layer receipt information.
  • the first application layer receipt information includes a second parsing result, and the second parsing result is used to indicate that the receiving device fails to decode.
  • the first application layer receipt information includes a third parsing result
  • the third parsing result is used to indicate that the receiving device parses the application layer message successfully.
  • the method further includes: when the receiving device is the Beidou network device 200, sending the original data to the cellular user equipment through the cellular network.
  • the method before the receiving device receives the first MDCP PDU of the first application layer message sent by the sending device, the method further includes: the receiving device acquires the first inbound data sent by the sending device at the PHY layer .
  • the receiving device performs physical layer processing based on the first inbound data to obtain the first user frame.
  • the receiving device presents the first user frame as the first SLC PDU in the SLC layer of the receiving device from the PHY layer to the SLC layer of the receiving device.
  • the method further includes: the receiving device receives X number of SLC PDUs in the first SLC SDU sent by the sending device, where X is a positive integer.
  • the X SLC PDUs include the first SLC PDU
  • the frame header information of the first SLC PDU includes the frame total number field and the frame sequence number field.
  • the frame total number field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and N is a positive integer, 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 receiving device When X is less than N, the receiving device sends a second ACK to the sending device, wherein the second ACK is used to indicate the frame sequence number of the SLC PDU not received by the receiving device in the first SLC SDU.
  • the method further includes: when X is equal to N, the receiving device converts the X SLC PDUs at the SLC layer Splicing into the first SLC SDU, and reporting the first SLC SDU as the first MDCP PDU of the MDCP layer from the SLC layer of the receiving device to the MDCP layer of the receiving device.
  • the method further includes: when X is equal to N, the receiving device sends the first ACK to the sending device, Wherein, the first ACK is used to indicate that the receiving device has received all the N SLC PDUs in the first SLC SDU.
  • the receiving device obtains the application layer message based on the first MDCP PDU, Specifically include: the receiving device splices M MDCP PDUs at the MDCP layer to obtain an MDCP SDU, and reports the MDCP SDU as an application layer message from the MDCP layer to the application layer.
  • the receiving device sends the first application layer receipt information to the sending device, which specifically includes: the receiving device sends the first application layer receipt information from the application layer of the receiving device to the receiving device through a preset interface. SLC layer.
  • the receiving device After adding frame header information to the first application layer receipt information at the SLC layer, the receiving device sends the first application layer receipt information added with frame header information to the physical layer to obtain a receipt frame.
  • the frame header information includes a frame type field, and the frame type field is used to indicate the frame type of the user frame.
  • the receiving device sends the acknowledgment frame to the sending device.
  • the above-mentioned sending device is a terminal
  • the receiving device is a Beidou network device.
  • the sending device is a Beidou network device
  • the receiving device is a terminal.
  • the present application provides a Beidou communication system, including: terminals and Beidou network equipment; wherein:
  • the sending device is configured to send the first MDCP PDU of the first application layer message to the receiving device.
  • the receiving device is configured to receive the first MDCP PDU.
  • the receiving device is further configured to obtain the first application layer message based on the first MDCP PDU after determining that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs in the first application layer message.
  • M is a positive integer.
  • the receiving device is further configured to generate first application layer receipt information, where the first application layer receipt information is used to indicate the result of parsing the first application layer packet by the receiving device.
  • the receiving device is further configured to send the first application layer receipt information to the sending device.
  • the sending device is configured to receive the first application layer receipt information.
  • the sending device may also execute the method in any possible implementation manner of the foregoing first aspect.
  • the receiving device may also execute the method in any possible implementation manner of the foregoing first aspect.
  • the above-mentioned sending device is a terminal
  • the receiving device is a Beidou network device.
  • the sending device is a Beidou network device
  • the receiving device is a terminal.
  • the present application provides a communication device, including one or more processors, one or more memories, and a transceiver.
  • the transceiver, the one or more memories are coupled to the one or more processors, the one or more memories are used to store computer program codes, the computer program codes include computer instructions, and when the one or more processors execute the computer instructions, the The communication device executes the method in any possible implementation manner of the first aspect or the second aspect above.
  • the communication device may be a terminal or other product form equipment.
  • the present application provides a communication device, including one or more processors, one or more memories, and a transceiver.
  • the transceiver, the one or more memories are coupled to the one or more processors, the one or more memories are used to store computer program codes, the computer program codes include computer instructions, and when the one or more processors execute the computer instructions, the The communication device executes the method in any possible implementation manner of the first aspect or the second aspect above.
  • the communication device may be Beidou network equipment, or any network element or a combination of multiple network elements in the Beidou network equipment.
  • the present application provides a computer storage medium, including computer instructions.
  • the computer instructions When the computer instructions are run on the computer, the computer is made to execute the method in any possible implementation manner of the first aspect above.
  • the present application provides a computer storage medium, including computer instructions.
  • the computer instructions When the computer instructions are run on the computer, the computer is made to execute the method in any possible implementation manner of the second aspect above.
  • the present application provides a computer program product, which, when the computer program product is run on a computer, causes the computer to execute the method in any possible implementation manner of the first aspect above.
  • the present application provides a computer program product, which, when the computer program product is run on a computer, causes the computer to execute the method in any possible implementation manner of the second aspect above.
  • the present application provides a chip or a chip system, which is applied to a terminal, and includes 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 manner of the first aspect or the second aspect above.
  • FIG. 1A is a schematic diagram of a Beidou communication system provided by an embodiment of the present application.
  • FIG. 1B is a schematic diagram of a Beidou communication system provided by an embodiment of the present application.
  • FIG. 1C is a schematic diagram of a Beidou communication system provided by an embodiment of the present application.
  • 2A-2B are schematic diagrams of an inbound protocol in a Beidou communication system provided by an embodiment of the present application.
  • 3A-3B are schematic diagrams of an outbound protocol in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 4 is a schematic diagram of an ACK processing flow in a Beidou communication system provided in an embodiment of the present application
  • FIG. 5 is a schematic diagram of a protocol processing flow in a Beidou communication system provided by an embodiment of the present application
  • FIG. 6A is a schematic diagram of inbound transmission in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 6B is a schematic diagram of outbound transmission in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of an application layer receipt mechanism in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram of an application layer message in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a receipt frame in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a receipt frame in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 11 is a schematic diagram of an application layer receipt mechanism in a Beidou communication system provided by an embodiment of the present application.
  • FIG. 12 is a schematic diagram of a hardware structure provided by an embodiment of the present application.
  • FIG. 13 is a schematic flowchart of an application layer receipt transmission method in the Beidou communication system provided by an embodiment of the present application
  • FIG. 14 is a schematic structural diagram of a communication device provided by an embodiment of the present application.
  • FIG. 15 is a schematic structural diagram of another communication device provided by an embodiment of the present application.
  • FIG. 16 is a schematic structural diagram of another communication device provided by an embodiment of the present application.
  • FIG. 17 is a schematic structural diagram of another communication device provided by an embodiment of the present application.
  • first and second are used for descriptive purposes only, and cannot be understood as implying or implying relative importance or implicitly specifying the quantity of indicated technical features. Therefore, the features defined as “first” and “second” may explicitly or implicitly include one or more of these features. In the description of the embodiments of the present application, unless otherwise specified, the “multiple” The meaning is two or more.
  • a Beidou communication system 10 provided in the embodiment of the present application is introduced below.
  • Beidou communication system 10 may include but not limited to terminal 100 , Beidou short message satellite 21 , Beidou network equipment 200 , short message center 25 , terminal 300 and so on.
  • the Beidou communication system 10 may also include an emergency rescue platform 26 and an emergency rescue center 27 .
  • the terminal 100 of the Beidou network can send short message information to the terminal 300 of the cellular network.
  • the terminal 100 can first send the short message information to the Beidou short message satellite 21, and the Beidou short message satellite 21 only relays, and can directly forward the short message information sent by the terminal 100 to the Beidou network equipment 200 on the ground .
  • the Beidou network device 200 can analyze the short message information forwarded by the satellite according to the Beidou communication protocol, and forward the message content parsed from the short message information to a short message service center (Short message service center, SMSC) 25 .
  • SMSC short message service center
  • the short message center 25 can forward the content of the message to the terminal 300 through a traditional cellular communication network.
  • the Beidou network device 200 may also send the emergency rescue message sent by the terminal 100 to the emergency rescue center 27 through the emergency rescue platform 26 .
  • the terminal 300 of the cellular network may be referred to as cellular user equipment
  • the terminal 300 can send the short message to the short message center 25 through a traditional cellular communication network (also called a cellular 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 through the Beidou short message satellite 21 .
  • the above-mentioned Beidou network equipment 200 may include a Beidou ground sending/receiving station 22, a Beidou central station 23 and a Beidou short message fusion communication platform 24.
  • the Beidou ground transmitting/receiving station 22 may include one or more devices respectively having a sending function and one or more devices having a receiving function, or may include one or more devices having a sending function and a receiving function, here Not limited.
  • the Beidou ground sending/receiving station 22 can be used for the Beidou network device 200 to process data at the physical layer (physical layer protocol, PHY).
  • the Beidou central station 23 can be used for the data processing function of the Beidou network equipment 200 in the satellite link control layer and the message data convergence protocol (message data convergence protocol, MDCP).
  • the Beidou short message fusion communication platform 24 can be used to process data at the application layer (application layer protocol, APP).
  • the sending device may send data to the receiving device.
  • the receiving device may send an acknowledgment character (ACK) of the SLC layer to the sending device.
  • ACK acknowledgment character
  • the sending device can determine whether the receiving device successfully receives the data frame based on the ACK.
  • FIG. 1B shows an inbound data transmission process in a Beidou communication system provided by an embodiment of the present application.
  • data inbound may refer to the terminal 100 sending data to the Beidou network device 200 .
  • the terminal 100 may send a data frame to the Beidou ground transceiver station 22 .
  • the Beidou ground transceiver station 22 can send the data frame to the Beidou central station 23 .
  • the Beidou central station 23 can aggregate the data frames into an application layer message and report it to the Beidou short message fusion communication platform 24 .
  • the Beidou central station 23 may return an ACK of the SLC layer to the terminal 100 after receiving the data frame sent by the terminal 100 .
  • the ACK can be used to indicate whether the Beidou network device 200 has successfully received the data frame sent by the terminal 100 .
  • the data frame may refer to the SLC PDU in the embodiment of the present application.
  • Fig. 1C shows a data outbound transmission process in the Beidou communication system provided by the embodiment of the present application.
  • outbound data may refer to the BDS network device 200 sending data to the terminal 100 .
  • the Beidou short message fusion communication platform 24 can send the application layer message to the Beidou central station 23; then, the Beidou central station 23 can split the application layer message into one or more data frames, and send the one or more Multiple data frames are sent to the terminal 100 through the Beidou ground transceiver station 22 and the Beidou short message satellite 21 .
  • the terminal 100 may return an ACK of the SLC layer to the Beidou network device 200.
  • the ACK can be used to indicate whether the terminal 100 has successfully received the data frame sent by the Beidou network device 200 .
  • the data frame may refer to the SLC PDU in the embodiment of the present application.
  • the Beidou network device 200 can splice the data frames sent to multiple terminals at the SLC layer to obtain outbound data, and then send the outbound data to all terminals . Therefore, the outbound resources of the SLC layer of the Beidou network device 200 are in short supply, and the processing of retransmitted data will cause a loss of computing resources to the Beidou network device 200 . Therefore, after sending the data, the Beidou network device 200 can clear the cache of the sent data. Similarly, after receiving the data frame sent by the Beidou network device 200, the terminal 100 does not return the AKC of the SLC layer to the Beidou network device 200. During outbound transmission, there is no retransmission mechanism at the SLC layer.
  • FIG. 2A shows a schematic diagram of a protocol encapsulation architecture of inbound data of a Beidou communication system 10 provided in an embodiment of the present application.
  • the Beidou message transmission protocol layer on the terminal 100 can be divided into an application layer, a message data aggregation layer, a satellite link control layer and a physical layer.
  • the workflow of the Beidou message transmission protocol on the terminal 100 can be as follows:
  • the terminal 100 can encode and compress the original data to obtain compressed data.
  • Terminal 100 may encrypt the compressed data to obtain encrypted data.
  • message header information before the encrypted data to obtain an application layer message.
  • the original data may include but not limited to text information input by the user, indication of the number of receiving users, ID of the receiving user, location information of the terminal 100, voice, image, animation, etc.
  • the packet header information may include, but not limited to, a compression indication field, an encryption indication field, and the like.
  • the compression indication field may be used to indicate the encoding and compression algorithm type used by the terminal 100 to compress data.
  • the encryption indication field is used to indicate the encryption algorithm type used by the terminal 100 to encrypt data.
  • the terminal 100 may add the above-mentioned compression indication field before the compressed data.
  • the terminal 100 uses the key to encrypt the compressed data added with the compression indication field to obtain encrypted data.
  • the terminal 100 can obtain the application layer message sent by the APP layer through the interlayer interface, and use the application layer message as a service data unit (server data unit, SDU) of the MDCP layer, referred to as MDCP SDU.
  • MDCP SDU service data unit
  • the terminal 100 can add padding to a specified length at the end of the MDCP SDU, and add a redundant length indication field to the MDCP SDU.
  • the redundant length indication field may 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_segment), and add a follow-up indication to the header of each MDCP segment data field to obtain the protocol data unit (protocol data unit, PDU) of the MDCP layer, referred to as MDCP PDU.
  • MDCP PDU includes M_segment and successor indication fields.
  • the successor indication field can be used to indicate the order of the current MDCP PDU in multiple MDCP PDUs in the same MDCP SDU, or the current MDCP PDU is the only MDCP PDU of the MDCP SDU.
  • the terminal 100 can obtain the MDCP PDU issued by the MDCP layer through the inter-layer interface as the SDU of the SLC layer, that is, the SLC SDU.
  • the terminal 100 can segment the SLC SDU into one or more (for example, 4) fixed-length SLC segment data (S_segment), and add frame header information to each S_segment header to obtain the SLC layer PDU, that is, SLC PDU.
  • the frame header information includes a service data unit alternated indicator (service data unit alternated indicator, SAI) field, a frame total number field, and a frame sequence number field.
  • SAI service data unit alternated indicator
  • the SAI field can be used to indicate whether the SLC PDU belongs to a SLC SDU that has not been sent.
  • the total number of frames field can be used to indicate the total number of SLC PDUs included in the SLC SDU to which the SLC PDU belongs.
  • 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.
  • the terminal 100 can obtain the SLC PDU issued by the SLC layer through the interlayer interface, and use the SLC PDU as a user frame using the PHY layer.
  • the terminal 100 may perform physical layer processing (for example, operations such as encoding, pilot insertion, modulation, and spectrum spreading) on user frames to obtain inbound data.
  • the terminal 100 can send the inbound data to the Beidou short message satellite 21 , and forward it to the Beidou network device 200 via the Beidou short message satellite 21 .
  • FIG. 2B shows a schematic diagram of a protocol analysis architecture of inbound data of the Beidou communication system 10 provided in the embodiment of the present application.
  • the Beidou message transmission protocol layer on the Beidou network device 200 can be divided into an application layer, a message data aggregation layer, a satellite link control layer and a physical layer.
  • the Beidou network device 200 may include, but not limited to, the Beidou ground transceiver station 22 , the Beidou central station 23 and the Beidou short message integrated 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.
  • the workflow of the Beidou message transmission protocol on the terminal 100 can be as follows:
  • the Beidou network device 200 can obtain the inbound data sent by the terminal 100 .
  • the Beidou network device 200 performs physical layer processing (for example, despreading, demodulation, de-pilot, decoding, etc.) on the inbound data to obtain user frames, and the Beidou network device 200 can present the user frames to the SLC layer through the interlayer interface , as the SLC PDU of the SLC layer.
  • physical layer processing for example, despreading, demodulation, de-pilot, decoding, etc.
  • the Beidou network device 200 can splice the 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 interlayer interface as the MDCP PDU of the MDCP layer.
  • the Beidou network device 200 can splice together all MDCP PDUs belonging to the same MDCP SDU according to the receiving time, and remove the padding data and redundant length indication fields of the spliced MDCP PDUs to obtain the MDCP SDU.
  • the Beidou network device 200 can present the MDCP SDU to the APP layer through the interlayer interface as an application layer message received by the APP layer.
  • the Beidou network device 200 can decrypt the encrypted data in the application layer message based on the message header of the application layer message to obtain compressed data.
  • the Beidou network device 200 can decompress and decode the compressed data to obtain the original data.
  • FIG. 3A shows a schematic diagram of a protocol encapsulation architecture of outbound data of the Beidou communication system 10 provided in the embodiment of the present application.
  • the Beidou message transmission protocol layer on the Beidou network device 200 can be divided into an application layer, a message data aggregation layer, a satellite link control layer and a physical layer.
  • the workflow of the Beidou message transmission protocol on the Beidou network device 200 can be as follows:
  • the Beidou network device 200 can encode and compress the original data to obtain compressed data.
  • the Beidou network device 200 can encrypt the compressed data to obtain encrypted data. And adding message header information before the encrypted data to obtain an application layer message.
  • the original data may include but not limited to data, text, semaphore, voice, image, animation, etc. sent by a third-party server (eg, short message center 25 ).
  • the packet header information may include, but not limited to, a compression indication field, an encryption indication field, and the like.
  • the compression indication field may be used to indicate the type of encoding and compression algorithm used by the Beidou network device 200 to compress data.
  • the encryption indication field is used to indicate the type of encryption algorithm used by Beidou network device 200 to encrypt data.
  • the Beidou network device 200 may add the above-mentioned compression indication field before the compressed data after encoding and compressing the original data to obtain the compressed data.
  • the Beidou network device 200 then encrypts the compressed data with the compression indication field added using the key to obtain encrypted data.
  • the Beidou network device 200 can obtain the application layer message sent by the APP layer through the interlayer interface, and use the application layer message as an MDCP SDU.
  • the Beidou network device 200 can split the MDCP SDU into one or more fixed-length MDCP segment data (M_segment), and add a follow-up indication field to the header of each MDCP segment data to obtain the MDCP PDU, that is, the MDCP PDU includes M_segment and successor indication fields.
  • the successor indication field can be used to indicate the sequence of the current MDCP PDU in the same MDCP SDU.
  • the Beidou network device 200 can obtain the MDCP PDU sent by the MDCP layer through the interlayer interface as the SLC SDU.
  • the Beidou network device 200 can segment the SLC SDU into one or more (for example, 4) fixed-length SLC segment data (S_segment), and add frame header information to the header of each S_segment to obtain the SLC PDU.
  • S_segment fixed-length SLC segment data
  • the Beidou network device 200 can obtain the SLC PDU delivered by the SLC layer through the interlayer interface as a user frame.
  • the Beidou network device 200 can stitch user frames (also called data frames) of multiple users or one user together, and add a frame header (such as a version number) and a check digit to obtain a physical frame.
  • the Beidou network device 200 can perform physical layer processing on the physical frame (eg, encoding, pilot insertion, modulation, spectrum spreading, etc.) to obtain encoded data of the message branch (S2C-d branch).
  • the Beidou network device 200 can combine the coded data of the S2C-d branch and the pilot data (also called secondary code) of the pilot branch (S2C-p branch) to form pilot coded data, that is, outbound data. And the outbound data is sent to the Beidou short message satellite 21, and relayed to one or more terminals via the Beidou short message satellite 21.
  • the pilot data of the S2C-p branch is related to the satellite beam. When the satellite beam is known information, the pilot data of the S2C-p branch is also known without decoding. The coded data of the S2C-d branch needs to be decoded.
  • FIG. 3B shows a schematic diagram of a protocol analysis framework for outbound data of the Beidou communication system 10 provided in the embodiment of the present application.
  • the Beidou message transmission protocol layer on the terminal 100 can be divided into an application layer, a message data aggregation layer, a satellite link control layer and a physical layer.
  • the terminal 100 can capture the coded data of the S2C-d branch based on the secondary code of the S2C-p branch sent by the Beidou network device 200 . After capturing the coded data of the S2C-d branch, the terminal 100 can perform physical layer processing (for example, despreading, demodulation, de-pilot, decoding, etc.) on the coded data of the S2C-d branch to obtain the physical frame . The terminal 100 may extract user frames belonging to the terminal 100 from the physical frames. The terminal 100 can present the user frame to the SLC layer through the interlayer interface as an SLC PDU of the SLC layer.
  • physical layer processing for example, despreading, demodulation, de-pilot, decoding, etc.
  • the terminal 100 can splice the SLC PDUs belonging to the same SLC SDU into one SLC SDU.
  • the terminal 100 can present the SLC SDU to the MDCP layer through the interlayer interface as the MDCP PDU of the MDCP layer.
  • the terminal 100 can retransmit the current SLC SDU/send the next SLC SDU/stop sending the SLC SDU.
  • the terminal 100 can splice one or more MDCP PDUs into one MDCP SDU.
  • the terminal 100 can present the MDCP SDU to the APP layer through the interlayer interface as an application layer message received by the APP layer.
  • the terminal 100 may decrypt the application layer message to obtain compressed data.
  • the terminal 100 decompresses and decodes the compressed data to obtain the original data.
  • FIG. 4 shows a schematic diagram of an ACK processing flow in the Beidou communication system 10 provided in the embodiment of the present application.
  • the sending device may generate an application layer packet at the application layer. Then, the sending device can send the application layer message to the MDCP layer as the MDCP SDU of the MDCP layer. Then, the sending device can subpackage the MDCP SDU into multiple MDCP PDUs at the MDCP layer. Then, the sending device can send the MDCP PDU to the SLC layer as the SLC SDU of the SLC layer, and frame the SLC SDU into N SLC PDUs at the SLC layer, where N is a positive integer (for example, 4).
  • the frame header information of the SLC PDU includes a service data unit alternated indicator (service data unit alternated indicator, SAI) field, a frame total number field, and a frame sequence number field.
  • SAI service data unit alternated indicator
  • the SAI field can be used to indicate whether the SLC PDU belongs to an unsent SLC SDU.
  • the total number of frames field can be used to indicate the total number of SLC PDUs included in the SLC SDU to which the SLC PDU belongs.
  • 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.
  • the sending device can send the SLC PDU of the SLC SDU to the receiving device.
  • the receiving device can judge whether it has received all the SLC PDUs of the SLC SDU based on the frame header information of the SLC PDU.
  • the receiving device may send the first ACK to the sending device.
  • the first ACK may be used to indicate that the receiving device has received all SLC PDUs of the SLC SDU.
  • the sending device can determine at the SLC layer that the receiving device has received the SLC PDU of the SLC SDU. If the sending device is the SLC PDU of the last SLC SDU of the MDCP SDU sent by the sending device, the sending device may end the sending operation. If the SLC PDU of the MDCP SDU sent by the sending device is not the SLC PDU of the last SLC SDU, the sending device can continue to send the SLC PDU of the next SLC SDU of the MDCP SDU.
  • the receiving device may send a second ACK to the sending device.
  • the second ACK may be used to indicate that the receiving device has not received all SLC PDUs of the SLC SDU.
  • the sending device may retransmit all SLC PDUs of the SLC SDU to the receiving device after receiving the second ACK.
  • the second ACK may also indicate the frame sequence number of the unreceived SLC PDU.
  • the sending device may retransmit the unreceived SLC PDU indicated by the second ACK to the receiving device.
  • the sending device after receiving the second ACK, the sending device retransmits the SLC PDU not received by the receiving device, and after receiving the SLC PDU, the receiving device may feed back the first ACK to the sending device.
  • the sending device in the inbound process, may be the terminal 100 and the receiving device may be the Beidou network device 200 .
  • the sending device may be the Beidou network device 200
  • the receiving device may be the terminal 100 .
  • the terminal 100 does not need to maintain communication with the Beidou network device 200 at all times.
  • the terminal 100 only needs to send a service request to the Beidou network device 200 during communication, and the Beidou network device 200 sends a service response to the terminal 100 based on the service request.
  • the Beidou network device 200 is provided with a retransmission mechanism at the SLC layer, the computational burden is heavy, and the beneficial effect is not obvious.
  • the sending device does not retransmit the SLC PDU of the SLC SDU to the receiving device after receiving the second ACK.
  • the sending device may also stop sending SLC SDUs to the Beidou network device 200. In this way, the Beidou network device 200 does not retransmit data at the SLC layer, which can better save limited transmission resources.
  • the terminal 100 may not send the feedback ACK of the SLC layer to the Beidou network device (including the first ACK and second ACK).
  • Fig. 5 shows a schematic flow chart of protocol processing of data by the MDCP layer and the SLC layer of the Beidou communication system 10 provided in the embodiment of the present application.
  • the sending device in the inbound process, is the terminal 100 and the receiving device is the Beidou network device 200 .
  • the sending device is the Beidou network device 200, and the receiving device is the terminal 100.
  • the sending device can split the MDCP SDU into one or more fixed-length MDCP segment data (M_segment), and add a follow-up indication field to the header of each MDCP segment data , get the MDCP PDU, that is, the MDCP PDU includes M_segment and successor indication fields.
  • MDCP segment data M_segment
  • successor indication fields M_segment and successor indication fields
  • the sending device can add padding data and a redundant length indication field to the MDCP SDU. Then, the sending device can split the MDCP SDU with padding data and redundant length indication field into one or more fixed-length MDCP segment data, and add a subsequent indication field at the header of each MDCP segment data, Get MDCP PDU.
  • the sending device can directly split the MDCP SDU into one or more fixed-length MDCP segment data, and add a follow-up indication field to the header of each MDCP segment data to obtain MDCP PDUs.
  • the sending device can store the split MDCP PDU into the MDCP layer sending buffer (MDCP Tx buffer) in the order of high bit to low bit:
  • the data length of the subsequent indication field may occupy 2 bits.
  • the meaning of the value of the subsequent indication field can be as follows:
  • MDCP PDU 01 Indicates that the MDCP PDU is the starting MDCP PDU among multiple MDCP PDUs in this MDCP SDU;
  • MDCP PDU is an intermediate MDCP PDU among multiple MDCP PDUs in this MDCP SDU, that is, refers to other MDCP PDUs in this MDCP SDU except the initial MDCP PDU and the last MDCP PDU;
  • the terminal 100 can split the MDCP SDU into three MDCP PDUs, wherein, according to the order of high bits to low bits, the three MDCP PDUs are MDCP PDU0, MDCP PDU1 and MDCP PDU2.
  • the terminal 100 since MDCP PDU0 is the initial MDCP PDU in the current MDCP SDU, the terminal 100 can set the value of the successor indication field in MDCP PDU0 to "01".
  • MDCP PDU1 is an intermediate MDCP PDU in the current MDCP SDU, terminal 100 may set the value of the successor indication field in MDCP PDU1 to "10".
  • MDCP PDU2 is the last MDCP PDU in the current MDCP SDU, and terminal 100 can set the value of the successor indication field in MDCP PDU2 to "11".
  • the sending device can control the SLC PDU sending strategy of the SLC layer through the SLC layer sending state controller at the SLC layer, including the initial transmission and retransmission of the SLC PDU.
  • the sending device may also control the sending and retransmission of the SLC PDU based on the reception feedback (eg, ACK) sent by the receiving device.
  • the sending device can obtain the MDCP PDU sent by the MDCP layer through the interlayer interface as the SLC SDU. Among them, when the sending device sends the previous SLC SDU to the receiving device and confirms that the receiving device receives it successfully, it will obtain the next MDCP PDU from the MDCP layer as the next SLC SDU and send it to the receiving device.
  • the sending device may deliver MDCP PDU0 among MDCP PDU0, MDCP PDU1 and MDCP PDU2 to the SLC layer.
  • the sending device first obtains the MDCP PDU0 issued by the MDCP layer through the interlayer interface, and the sending device can send the MDCP PDU0 as the first SLC SDU (that is, SLC SDU0) of the SLC layer in the message transmission process to the receiving device.
  • the sending device determines that the receiving device has sent the data of SLC SDU0 to the receiving device
  • the sending device can obtain MDCP PDU1 from the MDCP layer, and use MDCP PDU1 as the second SLC SDU in this message transmission process (that is, SLC SDU1 ) to the receiving device.
  • the sending device After the sending device confirms that the receiving device has sent the data of the second SLC SDU to the receiving device, the sending device can obtain MDCP PDU2 from the MDCP layer, and send MDCP PDU2 as the last SLC SDU in this message transmission process to the receiving device equipment.
  • the sending device can send all MDCP PDUs of the MDCP SDUs of the MDCP layer to the SLC layer through the inter-layer interface as SLC SDUs of the SLC layer.
  • the sending device sends the previous SLC SDU to the receiving device and confirms that the receiving device has successfully received it, it sends the next SLC SDU to the receiving device.
  • the sending device may deliver MDCP PDU0, MDCP PDU1 and MDCP PDU2 to the SLC layer.
  • the sending device first obtains the MDCP PDU0, MDCP PDU1, and MDCP PDU2 issued by the MDCP layer through the interlayer interface, and the sending device can use MDCP PDU0 as the first SLC SDU of the SLC layer in this message transmission process , SLC SDU0).
  • Use MDCP PDU2 as the third SLC SDU (ie, SLC SDU2) of the SLC layer in this message transmission process.
  • the sending device After the sending device determines that the receiving device has sent the data of SLC SDU0 to the receiving device, the sending device can send SLC SDU1 to the receiving device, and so on.
  • the sending device can segment the SLC SDU into one or more fixed-length SLC segment data (S_segment), and add frame header information to each S_segment header to obtain the SLC PDU.
  • the frame header information includes an SAI field, a frame total number field and a frame sequence number field.
  • the SAI field can occupy 1 bit.
  • the value of the SAI field may be "0" or "1".
  • the sending device can determine whether the SLC PDU to be sent currently belongs to an unsent SLC SDU, and if so, the sending device can set the value of the SAI field in the SLC PDU to match the previous SLC SDU session (including the SLC SDU initial transmission session or the SLC SDU session).
  • the value of the SAI field of the SLC PDU in the SDU retransmission session) is different; if not, the sending device 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.
  • the value of the SAI field in the SLC PDU is the same as the value of the SAI field in the SLC PDU in the previous SLC SDU session, it means that the SLC PDU is retransmission data.
  • each SLC SDU can include 4 SLC PDUs.
  • the values of the SAI fields of the 4 SLC PDUs in the first SLC SDU can all be "0"
  • the values of the SAI fields of the 4 SLC PDUs in the second SLC SDU that is, SLC SDU1
  • the values can all be "1”.
  • the values of the SAI fields of the 4 SLC PDUs in the 3rd SLC SDU may all be "0".
  • the receiving device analyzes the protocol of the received data at the SLC layer.
  • the receiving device can judge whether it has received all the SLC PDUs in an SLC SDU based on the frame header information of the SLC PDU.
  • the receiving device can splice the received one or more SLC PDUs into one SLC SDU in sequence according to the value of the frame sequence number field from small to large. Further, the receiving device may also send feedback information (for example, the first ACK) to the sending device, and after receiving the feedback information, the sending device may confirm that the receiving device has received all the SLC PDUs based on the feedback information.
  • feedback information for example, the first ACK
  • the receiving device may send feedback information (for example, the second ACK) to notify the sending device to retransmit the unreceived SLC PDUs after the SLC layer receiving window ends.
  • the receiving device can report the SLC SDU to the MDCP layer through the interlayer interface as an MDCP PDU.
  • the receiving device can control the sending strategy of the feedback information (for example, ACK) of the SLC layer and the splicing of the SLC PDU through the SLC layer receiving state controller at the SLC layer, based on the SAI field in the SLC PDU.
  • the duration of the SLC layer receiving state controller is the maximum retransmission time of the SLC PDU on the sending device.
  • the receiving device determines that all the SLC PDUs in the first SLC SDU (i.e.
  • the receiving device can splice these 4 SLC PDUs into SLC SDU0 in order of frame number from small to large, and report it to the MDCP layer , as MDCP PDU0 of the MDCP layer.
  • the receiving device can store MDCP PDU0 in the MDCP layer receive buffer (MDCP Rx buffer). Among them, the value of the successor indication field in MDCP PDU0 is "01".
  • the receiving state controller of the SLC layer of the receiving device may send an ACK to the sending state controller of the SLC layer of the sending device.
  • the ACK frame may include frame header information and a bitmap (bitmap) field.
  • the bitmap field can be used to feed back the receiving status of the SLC PDU of the receiving device.
  • the length of the bitmap field can be 1 bit, and the value of the bitmap can indicate whether all SLC PDUs of the SLC SDU are received. For example, when the value of the bitmap field is 0, it can indicate that all SLC PDUs that have not received the SLC SDU, and when the value of the bitmap field is 1, it can indicate that all SLC PDUs that have received the SLC SDU, here, the above example only uses It should not be construed as a limitation in the interpretation of this application.
  • the length of the bitmap field can be 4 bits, and each bit of the bitmap can mark whether the SLC PDU of the corresponding frame number is received.
  • the first bit of the bitmap can be used to mark the reception of the first SLC PDU (for example, the frame number is 00), and the second bit can be used to mark the reception of the second SLC PDU (for example, the frame number is 01). And so on.
  • the value of a certain bit of the bitmap is 0, it indicates that the receiving device has not received the SLC PDU corresponding to this bit within the receiving window.
  • the value of a certain bit of the bitmap is 1, it indicates that the receiving device has received the SLC PDU corresponding to the bit within the receiving window.
  • the sending device After receiving the first ACK sent by the receiving device, the sending device confirms that the receiving device has successfully received all SLC PDUs of SLC PDU0 based on the bitmap value of the first ACK, and starts sending SLC SDU1.
  • the receiving device has not received the SLC PDU with the SAI value of "0", the total frame value of "11", and the frame number of "01" in SLC SDU0 within the receiving window time, that is, all SLC PDUs that have not received SLC SDU0
  • the second SLC PDU in the frame (frame number is 01).
  • the SLC layer receiving state controller of the receiving device may send the second ACK to the SLC layer sending state controller of the sending device.
  • the value of the bitmap field of the second ACK is 1011.
  • the sending device receives the second ACK sent by the receiving device, it confirms that the receiving device has not received the second SLC PDU of SLC PDU0 based on the value of the bitmap, and the sending device retransmits the second SLC PDU of SLC PDU0.
  • the receiving device analyzes the protocol of the received data at the MDCP layer.
  • the receiving device can aggregate multiple MDCP PDUs in order of time based on the successor indication field in the MDCP PDU to obtain an MDCP SDU.
  • the receiving device can take out all the MDCP PDUs from the MDCP Rx buffer, and proceed according to the value of the successor indication field and the order of receiving time Splicing to get MDCP SDU.
  • the receiving device can report the MDCP SDU to the application layer through the interlayer interface as an application layer message.
  • the receiving device after splicing according to the value of the subsequent indication field and the order of receiving time, the receiving device also needs to remove the redundant indication field and padding data to obtain the MDCP SDU.
  • ACK can be used between the sending device and the receiving device to ensure that the data at the SLC layer will not be lost.
  • the sending device can determine whether the SLC layer of the receiving device has successfully received all the SLC PDUs of the application layer message sent by the sending device based on the ACK, but it does not mean that the application layer of the receiving device can successfully Parse the received application layer message. In this way, it cannot reliably indicate whether the receiving device can obtain the original data sent by the sending device (that is, the receiving device cannot parse out the original data of the application layer message).
  • the sending device sends data to the receiving device, the transmission is successful at the SLC layer, but the application layer decryption or decoding fails, the receiving device cannot parse the original data of the application layer message, and the sending device cannot confirm the analysis of the receiving device Condition. This will cause the user of the sending device to think that he has sent the Beidou short message to the receiving device, but the receiving device cannot obtain the original data of the successful reception. Moreover, even if the receiving device cannot obtain the original data, the operator confirms that the application layer message is sent/received successfully according to the SLC layer, and charges the user for the communication fee. The fee is unreasonable, resulting in poor user experience.
  • the terminal 100 sends emergency rescue information to the Beidou network device 200, it only confirms at the SLC layer. In this case, the user of the terminal 100 does not know, and will not send the second emergency rescue message.
  • the Beidou network device 200 cannot decode/decrypt the received application layer message, and cannot send the rescue information in the application layer message to the emergency rescue center 27, which delays the rescue time.
  • the present application provides an application layer receipt transmission method in the Beidou communication system.
  • the receiving device may analyze the application layer message, and obtain corresponding application layer receipt information based on the result of parsing the application layer message.
  • the receiving device can send the application layer receipt information to the sending device, and the sending device can confirm the situation of the receiving device parsing the application layer message based on the application layer receipt information (for example, parsing succeeds, parsing fails).
  • a credible message transmission mechanism can be established to ensure that the sending device can obtain information about the parsing of the application layer message by the receiving device.
  • the sending device may also perform corresponding operations based on the application layer receipt information. For example, if the application layer receipt information indicates that the receiving device parses the application layer message successfully, the sending device ends the sending operation. If the application layer receipt information indicates that the receiving device fails to parse the application layer message, the sending device may retransmit the application layer message. In this way, the transmission reliability of the Beidou communication system can be further guaranteed.
  • the following specifically introduces the transmission process of the application layer receipt transmission method in the Beidou communication system.
  • the terminal 100 sends data to the Beidou network device 200 .
  • the terminal 100 may send inbound data to the Beidou ground transceiver station 22 .
  • the Beidou ground transceiver station 22 can perform physical layer processing (for example, despreading, demodulation, depiloting, decoding, etc.) on the inbound data to obtain user frames, and send the user frames to the Beidou central station 23 .
  • the Beidou central station 23 can use the user frame as an SLC PDU and aggregate the SLC PDU into an application layer message and report it to the Beidou short message fusion communication platform 24.
  • the Beidou central station 23 may return an acknowledgment character (ACK) of the SLC layer to the terminal 100 after receiving the SLC PDU sent by the terminal 100.
  • the ACK can be used to indicate whether the Beidou network device 200 has successfully received the SLC PDU sent by the terminal 100.
  • the Beidou short message fusion communication platform 24 can analyze the received application layer message to obtain application layer analysis information.
  • the application layer resolution information may be used to indicate whether the Beidou network device 200 successfully parses the application layer message sent by the terminal 100 .
  • the Beidou network device 200 sends data to the terminal 100 .
  • the Beidou short message fusion communication platform 24 sends the application layer message to the Beidou central station 23, and the Beidou central station 23 can split the application layer message into multiple user frames and send the multiple user frames to Beidou Ground Transceiver Station 22.
  • the Beidou ground transceiver station 22 can splice the user frame into the physical frame, and perform physical layer processing on the physical frame (for example, encoding, pilot insertion, modulation, spread spectrum, etc.) to obtain outbound data and send the outbound data to Terminal 100.
  • the terminal 100 may perform physical layer processing on the outbound data (for example, operations such as despreading, demodulation, de-piloting, and decoding) to obtain a physical frame.
  • the terminal 100 can take out the user frame of the terminal 100 from the physical frame, and upload it to the SLC layer as an SLC PDU.
  • the terminal 100 can return the ACK of the SLC layer to the Beidou network device 200.
  • the ACK can be used to indicate that the terminal 100 receives the SLC PDU sent by the Beidou network device 200.
  • the terminal 100 can also aggregate the received SLC PDUs into an application layer message, and parse the obtained application layer message.
  • the terminal 100 may generate corresponding application layer receipt information based on a result of parsing the application layer message.
  • the application layer receipt information may be used to indicate whether the terminal 100 successfully parses the application layer message sent by the Beidou network device 200 .
  • a possible application layer receipt processing mechanism in the Beidou communication system 10 is specifically introduced below.
  • Fig. 7 shows a possible application layer receipt processing mechanism between the sending device and the receiving device in the embodiment of the present application.
  • the receiving device can send ACK and application layer receipt information to the sending device after receiving all the SLC PDUs corresponding to the application layer message sent by the sending device.
  • the receipt processing flow at the application layer is as follows:
  • the sending device generates an application layer packet.
  • the sending device can encode and compress the original data to obtain compressed data, then encrypt the compressed data to obtain encrypted data, and add header information to the encrypted data to obtain application layer messages.
  • the sending device sends the application layer message from the APP layer to the MDCP layer through the interlayer interface.
  • the sending device uses the application layer message as the MDCP SDU, and obtains M MDCP PDUs based on the MDCP SDU.
  • the sending device can use the application layer message as an MDCP SDU, and split the MDCP SDU into M MDCP PDUs, where M is a positive integer. It should be noted that when the sending device is the terminal 100, the sending device needs to add padding data and a redundant length indication field to the MDCP SDU. Then split the MDCP SDU added with padding data and redundant length indication field into M MDCP PDUs.
  • the sending device sends the MDCP PDU from the MDCP layer to the SLC layer through the interlayer interface.
  • the sending device uses the MDCP PDU as an SLC SDU, and frames the SLC SDU into N SLC PDUs.
  • the sending device can use MDCP PDUs as SLC SDUs and frame SLC SDUs into SLC PDUs.
  • MDCP PDUs as SLC SDUs and frame SLC SDUs into SLC PDUs.
  • the sending device sends the SLC PDU to the receiving device.
  • the sending device can send the SLC PDU from the SLC layer to the PHY layer through the interlayer interface.
  • the sending device can perform physical layer processing (such as encoding, pilot insertion, modulation, spectrum spreading, etc.) on the SLC PDU delivered by the SLC layer, and then forward it to the receiving device.
  • physical layer processing such as encoding, pilot insertion, modulation, spectrum spreading, etc.
  • the sending device is the terminal 100
  • the detailed description of the operations performed by the sending device at the PHY layer can refer to the embodiment described in FIG. 2A above.
  • the sending device is the Beidou network device 200
  • the details of the operations performed by the sending device at the PHY layer For description, reference may be made to the embodiment described in FIG. 3A above, and details are not repeated here.
  • the receiving device After the receiving device receives the data sent by the sending device at the PHY layer, it performs operations such as demodulation and decoding on the received data. Afterwards, the receiving device can upload the data after performing physical layer processing (such as despreading, demodulation, depiloting, decoding, etc.) to the SLC layer as the SLC PDU of the SLC layer.
  • physical layer processing such as despreading, demodulation, depiloting, decoding, etc.
  • the sending device sends a first ACK to the receiving device.
  • the receiving device can reply ACK to the sending device based on the frame header information of the SLC PDU.
  • the receiving device may send a second ACK to the sending device.
  • the second ACK can be used to indicate that the receiving device has not received all the SLC PDUs of the SLC SDU, and the second ACK can also indicate the frame sequence numbers of the SLC PDUs that have not been received.
  • the sending device may retransmit the unreceived SLC PDU indicated by the second ACK to the receiving device.
  • the receiving device may send the first ACK to the sending device.
  • the first ACK may be used to indicate that the receiving device has received all SLC PDUs of the SLC SDU.
  • the sending device determines that the receiving device has received the SLC PDU of the SLC SDU.
  • the sending device can continue to send the SLC PDU of the next SLC SDU of the MDCP SDU after receiving the first ACK.
  • the sending device can wait for the receiving device to send the application layer receipt information.
  • the receiving device since the receiving device only needs to receive all the SLC PDUs corresponding to the SLC SDU of the last SLC SDU, it can send the first ACK indicating that all SLC PDUs have been received to the sending device.
  • the receiving device needs to splicing all the SLC PDUs corresponding to the MDCP SDU to obtain the application layer message before it can start to parse the application layer message, and reply the corresponding application layer receipt information based on the result of parsing the application layer message, so the sending device receives the first
  • the ACK time is shorter than the application layer receipt information.
  • the receiving device splices the SLC PDU into an SLC SDU.
  • the detailed description of splicing the SLC PDU by the receiving device can refer to the embodiment shown in FIG. 5 , which will not be repeated here.
  • the receiving device uploads the SLC SDU from the SLC layer to the MDCP layer through the interlayer interface.
  • the receiving device can use the SLC SDU as the MDCP PDU, and obtain the MDCP SDU based on the MDCP PDU.
  • the receiving device can determine that all MDCP PDUs of the MDCP SDU have been received based on the successor indication field, and then splice the MDCP PDUs into MDCP SDUs in the order in which they are received.
  • the receiving device uploads the MDCP SDU from the MDCP layer to the APP layer through the interlayer interface.
  • the receiving device uses the MDCP SDU as an application layer message, parses the application layer message, and generates application layer receipt information based on a result of analyzing the application layer message.
  • the receiving device can use the MDCP SDU as an application layer message and parse the application layer message. After parsing the application layer message, the receiving device may generate corresponding application layer receipt information based on the result of parsing the application layer message.
  • the receiving device may generate application layer receipt information for indicating the parsing failure.
  • the receiving device may generate application layer receipt information for indicating successful parsing.
  • the application layer receipt information may be an error code.
  • the length of the error code can be 1 bit. When the value of the error code is 0, it may indicate that the receiving device fails to parse the application layer message. When the value of the error code is 1, it may indicate that the receiving device parses the application layer message successfully. It should be noted that the error code values and their meanings here are just examples.
  • the receiving device sends the application layer receipt information to the sending device.
  • the receiving device may encapsulate the application layer receipt information into a receipt frame, and send the receipt frame to the sending device.
  • the detailed description of the receipt frame obtained by the receiving device and the application layer receipt information obtained by the sending device can refer to the embodiments shown in FIG. 9 and FIG. 10 .
  • the receiving device may encapsulate the application-layer receipt information into an application-layer receipt message, and send the application-layer receipt message to the sending device.
  • the detailed description of the receiving device obtaining the application layer receipt message and the sending device obtaining the application layer receipt information can refer to the following embodiments, which will not be repeated here.
  • the sending device can determine the result of parsing the application layer message by the receiving device based on the received application layer receipt information at the APP layer.
  • the sending device may also perform corresponding operations based on the result of parsing the application layer message by the receiving device in the application layer receipt information. For example, if the application layer receipt information indicates that the receiving device parses the application layer message successfully, the sending device ends the sending operation or sends the next application layer message. If the application layer receipt information indicates that the receiving device fails to parse the application layer message, the sending device may retransmit the application layer message. In this way, the transmission reliability of the Beidou communication system can be further guaranteed.
  • the application layer receipt information may not only indicate whether the receiving device successfully parses the application layer message. Moreover, when the receiving device fails to parse, the application layer receipt information may also indicate the reason why the receiving device fails to parse the application layer message. In this way, the sending device can obtain the result of whether the receiving device successfully parses the application layer message from the application layer receipt information, and the reason for the parsing failure when the parsing fails.
  • the receiving device may determine a code (also called an error code) corresponding to a result of parsing the application layer message.
  • the error code is the application layer receipt information of the receiving device.
  • the length of the error code may be 4 bits.
  • the value of the error code is 0000, it may indicate that the receiving device successfully parses the application layer message.
  • the value of the error code is 0001, it may indicate that the receiving device fails to parse the application layer message, and the reason for the failure is a decryption error.
  • the value of the error code is 0010, it may indicate that the receiving device fails to parse the application layer message, and the reason for the failure is a decoding error. etc.
  • the receiving device may determine that the result of parsing the application layer message is a decryption error.
  • the receiving device may determine that the result of parsing the application layer message is a decoding error.
  • the receiving device determines that the result of parsing the application layer message is parsing success.
  • the receiving device can analyze the application layer message at the application layer, and after obtaining the result of analyzing the application layer message, send the error code corresponding to the result to the SLC layer through the interlayer interface.
  • the receiving device can add frame header information to the head of the error code to obtain a receipt frame of the SLC layer (also called an application layer receipt).
  • the receipt frame includes application layer receipt information (ie error code).
  • the receiving device can send the acknowledgment frame to the sending device.
  • the sending device can determine the situation of the receiving device parsing the application layer message based on the error code in the receipt frame.
  • the sending device may also perform corresponding operations based on the error code in the receipt frame.
  • the sending device can end the sending operation.
  • the sending device can determine that the reason for the receiving device's decryption error is that the key information of the sending device is different from that of the receiving device. After receiving the receipt frame, the sending device can negotiate with the receiving device to update the key information (including key, password book).
  • the sending device and the receiving device can negotiate a key through the cellular network device after returning to the cellular network.
  • the sending device and the receiving device negotiate key information
  • the key information of the sending device is changed to the key information of the receiving device.
  • the sending device can re-encrypt the compressed data based on the changed key information to obtain encrypted data.
  • the sending device then sends the application layer message including the encrypted data to the receiving device.
  • the receiving device can re-decrypt the encrypted data of the application layer message based on the changed key information.
  • the sending device can determine that the cause of the decoding error is that the coding compression algorithm of the sending device is different from that of the receiving device, and the sending device and the receiving device can Negotiate encoding compression algorithm.
  • the sending device and the receiving device can negotiate an encoding and encryption algorithm through the cellular network device.
  • the encoding compression algorithm of the sending device is changed to the encoding compression algorithm of the receiving device.
  • the sending device can re-encode and compress the original data based on the changed encoding and compression algorithm to obtain compressed data.
  • the sending device encrypts the compressed data to obtain the encrypted data, and then sends the application layer message including the encrypted data to the receiving device.
  • the receiving device can re-decode the compressed data based on the changed encoding and compression algorithm.
  • both the sending device and the receiving device store a codebook, which includes the encoding and compression algorithms used by the sending device and the receiving device.
  • a codebook which includes the encoding and compression algorithms used by the sending device and the receiving device.
  • the sending device may display prompt information 1 when it is determined based on the application layer receipt information that the receiving device successfully parses the application layer message.
  • the prompt message 1 may be used to prompt that the message is sent successfully.
  • the sending device may display prompt information 2 when determining that the receiving device fails to parse the application layer message based on the application layer receipt information.
  • the prompt message 2 can be used to prompt that the message sending fails.
  • the sending device may display prompt information 3 when it is determined based on the application layer receipt information that the receiving device fails to parse the application layer message and the failure reason is decryption failure.
  • Prompt message 3 can be used to prompt that message sending fails due to wrong key.
  • the prompt message 3 may prompt the user of the sending device to return to the cellular network to renew the key before sending the Beidou short message.
  • the sending device may display prompt information 4 when it is determined based on the application layer receipt information that the receiving device fails to parse the application layer message and the reason for the failure is decoding failure.
  • the prompt message 4 can be used to prompt that the message sending fails due to an incorrect encoding and encryption algorithm. Further, the prompt message 3 may remind the user of the sending device to return to the cellular network to update the encoding and encryption method before sending the Beidou short message.
  • the receiving device can be preset to only reply the ACK of the SLC layer after receiving all the SLC PDUs of the last SLC SDU corresponding to the application layer message of the sending device.
  • the receiving device may be preset to reply both the ACK of the SLC layer and the return receipt information of the application layer.
  • the receiving device may be preset to only reply to the application layer receipt information.
  • the sending device may add a return receipt indication field in the header of the application layer message.
  • the sending device may indicate whether the receiving device responds to the application layer receipt information through the receipt indication field.
  • the Beidou communication system can ensure the reliability of the transmission when it is necessary to confirm the result of the receiving device parsing the application layer message. In the case where there is no need to confirm the result of parsing the application layer message by the receiving device, transmission air interface resources are saved.
  • the sending device may perform encoding, compression, encryption and other operations on the original data to obtain encrypted data. And adding message header information to the encrypted data to obtain an application layer message.
  • the specific format of the application layer message may refer to FIG. 8 .
  • FIG. 8 shows an example of sending an application layer packet of a device.
  • Application layer messages consist of message headers and encrypted data.
  • the decrypted data may be obtained by compressing and encrypting the original data.
  • the message header information may include but not limited to return receipt indication field, encryption indication field, compression indication field and so on.
  • the receipt indication field may be used to indicate whether the receiving device needs to reply the application layer receipt information.
  • the length of the return receipt indication field may be 1 bit. When the value of the receipt indication field is 0, it may be used to instruct the receiving device not to reply the application layer receipt information. When the value of the receipt indication field is 1, it can be used to instruct the receiving device to reply the application layer receipt information.
  • the sending device can use the obtained application layer message delivered by the APP layer as an MDCP SDU.
  • the sending device can subpackage the MDCP SDU into one or more fixed-length MDCP segment data.
  • the sending device can add a follow-up indication field to the header of each MDCP segment data to obtain an MDCP PDU.
  • the successor indication field can be used to indicate the sequence of the current MDCP PDU in the same MDCP SDU.
  • the sending device may add padding data and a redundant length indication field to the MDCP SDU. And subpackage the MDCP SDU with padding data and redundant length indication field added into one or more fixed-length MDCP segment data.
  • the sending device can frame MDCP PDUs as SLC SDUs into SLC PDUs.
  • the sending device can process the SLC PDU at the physical layer (for example, encoding, pilot insertion, modulation, spread spectrum, etc.) to obtain a physical frame, and send the physical frame to the receiving device.
  • the physical layer for example, encoding, pilot insertion, modulation, spread spectrum, etc.
  • the receiving device may perform physical layer processing on the physical frame (for example, operations such as despreading, demodulation, depiloting, and decoding) and upload it to the SLC layer.
  • physical layer processing for example, operations such as despreading, demodulation, depiloting, and decoding
  • the receiving device can feed back an ACK to the sending device based on the reception of the SLC PDU. After the receiving device receives all the SLC PDUs corresponding to the SLC SDU, it can frame the SLC PDUs to obtain the SLC SDU.
  • the specific process of feeding back the ACK by the receiving device may refer to the foregoing embodiments, and details are not repeated here.
  • the receiving device can upload the SLC SDU to the MDCP layer as an MDCP PDU. After the receiving device determines that all MDCP PDUs of the MDCP SDU have been received based on the successor indication field, it can splice the MDCP PDUs into MDCP SDUs in the order of receipt, and upload the MDCP SDUs to the APP layer.
  • the receiving device can use the MDCP SDU as an application layer message and parse the application layer message. First, the receiving device may determine whether to reply the application layer receipt information based on the receipt indication field. If the receiving device determines not to reply the application layer receipt information based on the receipt indication field, the receiving device directly parses the application layer message.
  • the receiving device may generate corresponding application layer receipt information based on the result of parsing the application layer message after parsing the application layer message. After the receiving device generates the application layer receipt information, it can send the application layer receipt information to the sending device.
  • the receiving device may parse the receipt indication field at the MDCP layer. And judge whether to reply the application layer receipt information based on the value of the receipt indication field.
  • the application layer receipt information may be encapsulated as a receipt frame at the SLC layer. That is to say, the receipt indication field may indicate whether the receiving device responds to the application layer receipt information. The receipt indication field may indicate whether the receiving device responds to the receipt frame.
  • the receiving device determines that all MDCP PDUs of the MDCP SDU have been received based on the successor indication field, it can splice the MDCP PDUs into MDCP SDUs according to the order in which they are received. Afterwards, the receiving device may determine whether to reply the receipt frame based on the receipt indication field.
  • the receiving device When the receiving device determines not to reply to the receipt frame (for example, the value of the receipt indication field is 0), the receiving device uploads the MDCP SDU to the APP layer. At the APP layer, the receiving device can use the MDCP SDU as an application layer message and parse the application layer message.
  • the receiving device can directly upload the MDCP SDU to the APP layer, use the MDCP SDU as an application layer message and parse the application layer message. Wherein, the receiving device may also notify the APP layer to generate application layer receipt information. After parsing the application layer message, the receiving device may generate corresponding application layer receipt information based on the result of parsing the application layer message. The receiving device may encapsulate the application layer receipt information into a receipt frame and send the receipt frame to the sending device. The sending device may determine the result of parsing the application layer packet by the receiving device based on the application layer receipt information. Further, the sending device may perform a corresponding operation based on the application layer receipt information. For details, refer to the embodiment described in FIG. 7 above, which will not be repeated here.
  • the receiving device is the Beidou network device 200
  • the specific description of the receipt frame can refer to the embodiment described in FIG. 9 .
  • the Beidou network device 200 may generate a receipt frame at the SLC layer. Specifically, the Beidou network device 200 may send the application layer receipt information corresponding to the result of parsing the application layer message to the SLC layer. Wherein, the application layer receipt information may be a notification message, and the Beidou network device 200 may generate a receipt frame corresponding to the result of parsing the application layer message according to the notification message at the SLC layer.
  • the application layer receipt information may be an error code.
  • the Beidou network device 200 can write the application layer receipt frame information into the user information.
  • the length of the error code may be 4 bits, and each error code corresponds to a result of parsing the application layer message.
  • the meaning of some values of the error code can be as follows:
  • the Beidou network device 200 can add frame header information before the user information to obtain a receipt frame.
  • the frame header information may include but not limited to a start identification field, a frame length field, a user identity (identity, ID) field and a frame type field.
  • the start identification field may be used to identify the start position of a new user frame of the Beidou network device 200 .
  • the frame length field can be used to identify the length of the user frame.
  • the user ID field may be used to identify the device (eg, terminal 100) that received the application layer receipt.
  • the terminal 100 can extract the user frame belonging to the terminal 100 from the outbound data according to the value of the user ID field.
  • the frame type field can be used to identify the type of user frame.
  • the length of the frame type field may be 2 bits.
  • the value of the frame type field is 00, it can be identified that the current user frame is a general data frame. Among them, the general data frame can be used to transmit original data.
  • the value of the frame type field is 01, it can be identified that the current user frame is an ACK frame. Among them, the ACK frame can be used to confirm the transmission of the SLC PDU of the SLC layer.
  • the current user frame may be identified as a receipt frame. Wherein, the receipt frame may be used to confirm the parsing status of the application layer message of the application layer.
  • the user frame sent by the Beidou network device 200 to the terminal 100 is a receipt frame, so the value of the frame type field may be 10.
  • the Beidou network device 200 can splice the receipt frame and other user frames together, and add a version number field to the headers of multiple user frames. Wherein, the version number field may be used to indicate the version of the Beidou short message protocol.
  • the Beidou network device 100 can also add a check code (for example, a cyclic redundancy check (cyclic redundancy check, CRC) code) at the end of multiple user frames to obtain a physical frame.
  • the Beidou network device 200 can perform physical layer processing on the physical frame (such as encoding, pilot insertion, modulation, spread spectrum, etc.) and add a reserved segment to the physical frame to form a fixed-length physical time slot S2C-d Coded data for the branch.
  • the Beidou network device 200 can synchronously send the coded data of the S2C-d branch and the secondary code of the S2C-p branch to the Beidou short message satellite 21, and forward them to one or more terminals (including terminal 100).
  • the above-mentioned receipt frame processing mechanism is only for illustration, and the present application does not limit the specific operation of the receipt frame processing mechanism.
  • the terminal 100 can capture the coded data of the S2C-d branch based on the secondary code of the S2C-p branch sent by the Beidou network device 200 .
  • the terminal 100 can perform physical layer processing (for example, despreading, demodulation, de-pilot, decoding, etc.) on the coded data of the S2C-d branch to obtain the physical frame .
  • the user frame whose value of the user ID field is the same as the value of the user ID of the terminal 100 is extracted from the physical frame.
  • the terminal 100 can upload the error code in the receipt frame to the APP layer through the interlayer interface at the SLC layer, and based on the user
  • the error code in the information obtains the result of analyzing the application layer message by the Beidou network device 200.
  • the terminal 100 may perform corresponding operations for different results. Specifically, for a detailed description of the operations performed by the terminal 100, reference may be made to the embodiment described in FIG. 7 , and details are not repeated here.
  • the specific description of the receipt frame can refer to the embodiment described in FIG. 10 .
  • the terminal 100 may deliver the result of parsing the application layer message to the SLC layer.
  • the terminal 100 may write the application layer receipt information corresponding to the result of parsing the application layer message into the user information.
  • the application layer receipt information may be an error code.
  • the error code may be used to indicate the result of parsing the application layer message by the terminal 100. For a detailed description of the error code, please refer to the embodiment described in FIG. 9 above, which will not be repeated here.
  • the terminal 100 may add frame header information before the user information to obtain a receipt frame.
  • the frame header information may include but not limited to a version number field, a subtype indication field, a user ID field, a total number of frames field, a frame sequence number field, an SAI field, a reserved field (reserve, RSV) field and the like.
  • the version number field may be used to identify the version of the Beidou short message protocol.
  • the subtype indication field can be used to identify the type of user frame.
  • the length of the subtype indication field may be 2 bits.
  • the value of the subtype indication field is 00, it can be identified that the current user frame is a general data frame.
  • the general data frame may include but not limited to an emergency rescue frame, a position report frame, a message communication frame, and the like.
  • the value of the subtype indication field is 01, it can be identified that the current user frame is an ACK frame.
  • the value of the subtype indication field is 10
  • the current user frame may be identified as a receipt frame.
  • the Beidou network device 200 sends the receipt frame to the terminal 100, so the value of the subtype indication field may be 10.
  • the user ID field may be used to identify the device (terminal 100) receiving the application layer receipt.
  • the reserved domain field can be used in other fields of the subsequent Beidou communication system, and is not limited here.
  • the terminal 100 may send the receipt frame to the PHY layer.
  • the terminal 100 can use the receipt frame as a data segment, and send the corresponding physical frame to the Beidou short message satellite 21 after adding a synchronization header and a parity bit to the data segment, and send it to the Beidou short message satellite 21 via the Beidou short message satellite 21
  • the relay is forwarded to the Beidou network device 200.
  • the Beidou network device 200 After the Beidou network device 200 receives the physical frame, it can obtain the user frame through physical layer processing (such as despreading, demodulation, depiloting, decoding, etc.) and upload the user frame to the SLC layer. After the Beidou network device 200 can determine that the user frame is a receipt frame through the value of the subtype indication field at the SLC layer, the Beidou network device 200 can upload the error code of the receipt frame to the APP layer through the interlayer interface. At the APP layer, the Beidou network device 200 can obtain the result of parsing the application layer message by the terminal 100 based on the error code of the receipt frame.
  • physical layer processing such as despreading, demodulation, depiloting, decoding, etc.
  • the Beidou network device 200 may also perform corresponding operations based on the result of the terminal 100 parsing the application layer message. Specifically, reference may be made to the embodiment described above in FIG. 7 , and details are not repeated here.
  • the above-mentioned receipt frame processing mechanism is only for illustration, and the present application does not limit the specific operation of the receipt frame processing mechanism.
  • the receiving device may encapsulate the application layer receipt information into an application layer receipt message at the APP layer, and then the receiving device may send the application layer receipt message to the sending device.
  • the sending mechanism of the application layer message can be used to obtain the application layer receipt message, reducing the modification of the processing mechanism of the Beidou communication system.
  • the receiving device may use the application layer receipt information as the above original data.
  • the receiving device can encode and compress the application layer receipt information to obtain compressed data. Then encrypt the compressed data to obtain encrypted data. Afterwards, the receiving device can add message header information before the encrypted data to obtain an application layer receipt message.
  • the packet header information may include, but not limited to, an encryption indication field, a compression indication field, and a return receipt identification field.
  • an encryption indication field For the description of the encryption indication field and the compression indication field, reference may be made to the above embodiment described in FIG. 3A , which will not be repeated here.
  • the return receipt identification field may be used to indicate whether the application layer message includes application layer return receipt information.
  • the length of the receipt identification field may be 1 bit.
  • the application layer packet includes application layer receipt information. It should be noted that the application layer packet including the application layer receipt information may be referred to as an application layer receipt packet for short.
  • the application layer message does not include application layer receipt information.
  • the process of the receiving device generating the application layer receipt message and sending the application layer receipt message to the sending device is the same as the process of the sending device generating and sending the application layer message.
  • the process for the sending device to obtain the original data of the application-layer receipt message is the same as the above-mentioned process for the receiving device to obtain the original data of the application-layer message.
  • the sending device can determine whether the application layer message is an application layer receipt message based on the value of the receipt identification field.
  • the sending device determines that the receipt identification field indicates that the application layer message is an application layer receipt message
  • the sending device can determine the result of the receiving device parsing the application layer message based on the original data (that is, the application layer receipt information), the specific text
  • the receiving device may directly add packet header information before the application layer receipt information without compressing or encrypting the original data, so as to obtain the application layer receipt message.
  • the receiving device may set the value of the compression indication field in the message header information to not use a compression algorithm, and may set the value of the encryption indication field in the message header information to not use an encryption algorithm.
  • the header information of the application layer receipt message may not include the compression indication field and the encryption indication field.
  • FIG. 11 shows another possible application layer receipt processing mechanism between the sending device and the receiving device in the embodiment of the present application.
  • the receiving device after receiving the SLC PDU of the last SLC SDU corresponding to the application layer message sent by the sending device, the receiving device does not send the ACK of the SLC layer, but only sends the application layer receipt information to the sending device. In this way, when the sending device receives the application layer receipt information, it can prove that the receiving device has received all the SLC PDUs of the SLC SDU, and the receiving device can no longer send the ACK of the SLC PDU of the last SLC SDU, saving the air interface resources of the receiving device.
  • the sending device generates an application layer packet.
  • the sending device sends the application layer message from the APP layer to the MDCP layer through the interlayer interface.
  • the sending device uses the application layer message as an MDCP SDU, and obtains M MDCP PDUs based on the MDCP SDU.
  • the sending device sends the MDCP PDU from the MDCP layer to the SLC layer through the interlayer interface.
  • the sending device uses the MDCP PDU as an SLC SDU, and frames the SLC SDU into N SLC PDUs.
  • the sending device sends the SLC PDU to the receiving device.
  • step S1101 to step S1106 reference may be made to the above-mentioned embodiment in FIG. 7 , which will not be repeated here.
  • the receiving device splices the SLC PDU into an SLC SDU.
  • the receiving device uploads the SLC SDU from the SLC layer to the MDCP layer through the interlayer interface.
  • the receiving device can use the SLC SDU as the MDCP PDU, and obtain the MDCP SDU based on the MDCP PDU.
  • the receiving device can upload the MDCP SDU from the MDCP layer to the APP layer through the interlayer interface.
  • the receiving device can reply ACK to the sending device based on the frame header information of the SLC PDU after receiving the SLC PDU of the SLC SDU. If the receiving device determines that all SLC PDUs of the SLC SDU have not been received based on the frame header information, the receiving device may send a second ACK to the sending device. Wherein, the second ACK can be used to indicate that the receiving device has not received all the SLC PDUs of the SLC SDU, and the second ACK can also indicate the frame sequence numbers of the SLC PDUs that have not been received. After receiving the second ACK, the sending device may retransmit the unreceived SLC PDU indicated by the second ACK to the receiving device.
  • the receiving device determines that all SLC PDUs of the SLC SDU have been received based on the frame header information, the receiving device can splice the SLC PDUs to obtain the SLC SDU, and upload the SLC SDU to the MDCP layer.
  • the receiving device can treat the SLC SDU as an MDCP PDU.
  • the receiving device can judge whether the current MDCP PDU is the last MDCP PDU of the MDCP SDU based on the successor indication field of the MDCP PDU.
  • the receiving device may send the first ACK at the SLC layer.
  • the sending device receives the first ACK, it can send the next MDCP PDU of the MDCP SDU to the receiving device.
  • the receiving device may send the first message to the SLC layer at the MDCP layer, and the first message may be used to instruct the receiving device to send the first ACK to the sending device at the SLC layer.
  • the receiving device determines that the currently received MDCP PDU is the last MDCP PDU among all MDCP PDUs of the MDCP SDU based on the successor indication field, the receiving device can splice the MDCP PDUs into MDCP SDUs in the order they are received, and upload the MDCP SDUs to the APP layer.
  • the receiving device determines that the currently received MDCP PDU is the last MDCP PDU among all MDCP PDUs of the MDCP SDU based on the successor indication field, it does not send the first ACK at the SLC layer.
  • the first ACK is used to indicate that the receiving device has received all SLC PDUs of the currently sent SLC SDU at the SLC layer.
  • the receiving device uses the MDCP SUD as an application layer message, parses the application layer message, and generates application layer receipt information based on the result of parsing the application layer message.
  • the receiving device can use the MDCP SDU as an application layer message and parse the application layer message. After parsing the application layer message, the receiving device may generate corresponding application layer receipt information based on the result of parsing the application layer message.
  • the receiving device is the Beidou network device 200
  • the detailed description of the application layer receipt information generated by the receiving device can refer to the embodiment described in Figure 9 above.
  • the receiving device is the terminal 100
  • the detailed description of the application layer receipt information generated by the receiving device For description, reference may be made to the embodiment described in FIG. 10 above, and details are not repeated here.
  • the application layer receipt information can not only be used to indicate that the receiving device parses the application layer message, but also can be used to indicate that the receiving device has received all the SLC PDUs of the last SLC SDU at the SLC layer.
  • the receiving device sends the application layer receipt information to the sending device.
  • the process for the sending device to obtain the application layer receipt information may refer to the above-mentioned embodiments shown in FIG. 9 to FIG. 10 , which will not be repeated here.
  • the sending device After receiving the application layer receipt information, the sending device can determine the result of the receiving device parsing the application layer message based on the application layer receipt information. Further, the sending device may perform a corresponding operation based on the application layer receipt information. For a specific description, refer to the embodiment described in FIG. 7 above, which will not be repeated here.
  • the sending device may indicate whether the receiving device feeds back the application layer receipt information by adding a receipt indication field in the packet header. In this way, the sending device can decide whether to feed back the application layer acknowledgment, and in some situations where the application layer acknowledgment is not required, it saves the time for the receiving device to feed back the ACK.
  • the receiving device when the receiving device determines not to reply the application layer receipt information (for example, the value of the receipt indication field is 0), the receiving device sends the first ACK to the sending device at the SLC layer.
  • the receiving device determines to reply to the application layer receipt information (for example, the value of the receipt indication field is 0)
  • the receiving device can analyze the original data of the application layer message, and generate the application layer receipt information based on the result of parsing the application layer message, Then the application layer receipt information is sent to the sending device.
  • the receiving device when the receiving device judges whether to reply the application layer receipt information based on the receipt indication field, the receiving device may parse the receipt indication field at the MDCP layer, and judge whether to reply the application layer receipt information based on the value of the receipt indication field.
  • the sending device can determine the receiving status of the SLC layer of the receiving device and the status of parsing the application layer message by the receiving device only through the application layer receipt information. And because the receiving device only feeds back the application layer receipt information, the resources used by the receiving device for sending ACK frames can also be saved.
  • the receiving device may reply an ACK based on the frame header information of the SLC PDU.
  • the receiving device may send a second ACK to the sending device.
  • the second ACK can be used to indicate that the receiving device has not received all the SLC PDUs of the SLC SDU, and the second ACK can also indicate the frame sequence numbers of the SLC PDUs that have not been received.
  • the sending device may retransmit the unreceived SLC PDU indicated by the second ACK to the receiving device.
  • the receiving device determines that all SLC PDUs that have received the SLC SDU are determined based on the frame header information, the receiving device can splice the SLC PDUs to obtain the SLC SDU, and upload the SLC SDU to the MDCP layer as an MDCP PDU.
  • the receiving device can judge whether the current MDCP PDU is the last MDCP PDU of the MDCP SDU based on the successor indication field of the MDCP PDU.
  • the receiving device may notify the SLC layer to send the first ACK.
  • the sending device receives the first ACK, it can send the next MDCP PDU of the MDCP SDU to the receiving device.
  • the receiving device determines that the currently received MDCP PDU is the last MDCP PDU among all MDCP PDUs of the MDCP SDU based on the successor indication field, the receiving device can splice the MDCP PDUs in the order in which they are received to obtain the MDCP SDU. It should be noted that when the receiving device is the Beidou network device 200, the Beidou network device 200 can remove the padding data of the spliced MDCP PDU based on the redundant length indication field to obtain the MDCP SDU.
  • the receiving device may determine whether to reply to the sending device with application layer receipt information based on the receipt indication field.
  • the receiving device determines not to reply to the application layer receipt information (for example, the value of the receipt indication field is 0)
  • the receiving device notifies the SLC layer to send the first ACK to the sending device, and uploads the MDCP SDU to the APP layer.
  • the receiving device can use the MDCP SDU as an application layer message and parse the application layer message.
  • the receiving device determines that the reply application layer receipt information (for example, the value of the receipt indication field is 0)
  • the receiving device directly uploads the MDCP SDU to the APP layer, and parses the MDCP SDU as an application layer message.
  • the receiving device may simultaneously notify the APP layer to feed back the receipt information of the application layer.
  • the receiving device may generate corresponding application layer receipt information based on the result of parsing the application layer message.
  • the receiving device can send the application layer receipt information to the sending device.
  • the receiving device is the Beidou network device 200
  • the detailed description of the application layer receipt information generated by the receiving device can refer to the embodiment described in FIG. 9 above.
  • the receiving device is the terminal 100, the detailed description of the application layer receipt information generated by the receiving device Reference may be made to the embodiment described above in FIG. 10 , and details are not repeated here.
  • the sending device can determine the result of the receiving device parsing the application layer message based on the application layer receipt information.
  • the application layer receipt information may also be equivalent to the first ACK, and the sending device may confirm that the receiving device has received all SLC PDUs corresponding to the last MDCP PDU of the MDCP SDU based on the application layer receipt information.
  • the receiving device may be preset to reply application layer receipt information to the sending device. In this way, the receiving device automatically replies with the application layer receipt information without judging based on the receipt indication field.
  • the terminal 100 provided in the embodiment of the present application is introduced below.
  • the terminal 100 may be a mobile phone, a tablet computer, a desktop computer, a laptop computer, a handheld computer, a notebook computer, an ultra-mobile personal computer (UMPC), a netbook, as well as a cellular phone, a personal digital assistant (personal digital assistant) assistant, PDA), augmented reality (augmented reality, AR) device, virtual reality (virtual reality, VR) device, artificial intelligence (artificial intelligence, AI) device, wearable device, vehicle-mounted device, smart home device and/or smart For urban equipment, the embodiment of the present application does not specifically limit the specific type of the electronic equipment.
  • FIG. 12 shows a schematic diagram of a hardware structure provided by an embodiment of the present application.
  • the terminal 100 shown in FIG. 12 is only an example, and the terminal 100 may have more or fewer components than those shown in FIG. 12, may combine two or more components, or may have Different component configurations.
  • the various components shown in Figure 12 may be implemented in hardware, software, or a combination of hardware and software including one or more signal processing and/or application specific integrated circuits.
  • the terminal 100 may include: a processor 110, an external memory interface 120, an internal memory 121, a universal serial bus (universal serial bus, USB) interface 130, a charging management module 140, a power management module 141, a battery 142, an antenna 1, and an antenna 2 , mobile communication module 150, wireless communication module 160, audio module 170, speaker 170A, receiver 170B, microphone 170C, earphone jack 170D, sensor module 180, button 190, motor 191, indicator 192, camera 193, display screen 194, and A subscriber identification module (subscriber identification module, SIM) card interface 195 and the like.
  • SIM subscriber identification module
  • 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, bone conduction sensor 180M, etc.
  • the structure illustrated in the embodiment of the present invention does not constitute a specific limitation on the terminal 100 .
  • the terminal 100 may include more or fewer components than shown in the figure, or combine certain components, or separate certain components, or arrange different components.
  • the illustrated components can be realized in hardware, software or a combination of software and hardware.
  • the processor 110 may include one or more processing units, for example: the processor 110 may include an application processor (application processor, AP), a modem processor, a graphics processing unit (graphics processing unit, GPU), an image signal processor (image signal processor, ISP), controller, memory, video codec, digital signal processor (digital signal processor, DSP), baseband processor, and/or neural network processor (neural-network processing unit, NPU) wait. Wherein, different processing units may be independent devices, or may be integrated in one or more processors.
  • application processor application processor, AP
  • modem processor graphics processing unit
  • GPU graphics processing unit
  • image signal processor image signal processor
  • ISP image signal processor
  • controller memory
  • video codec digital signal processor
  • DSP digital signal processor
  • baseband processor baseband processor
  • neural network processor neural-network processing unit, NPU
  • the controller may be the nerve center and command center of the terminal 100 .
  • the controller can generate an operation control signal according to the instruction opcode and timing signal, and complete the control of fetching and executing the instruction.
  • a memory may also be provided in the processor 110 for storing instructions and data.
  • the memory in processor 110 is a cache memory.
  • the memory may hold instructions or data that the processor 110 has just used or recycled. If the processor 110 needs to use the instruction or data again, it can be called directly from the memory. Repeated access is avoided, and the waiting time of the processor 110 is reduced, thus improving the efficiency of the system.
  • processor 110 may include one or more interfaces.
  • the interface may include an integrated circuit (inter-integrated circuit, I2C) interface, an integrated circuit built-in audio (inter-integrated circuit sound, I2S) interface, a pulse code modulation (pulse code modulation, PCM) interface, a universal asynchronous transmitter (universal asynchronous receiver/transmitter, UART) interface, mobile industry processor interface (mobile industry processor interface, MIPI), general-purpose input and output (general-purpose input/output, GPIO) interface, subscriber identity module (subscriber identity module, SIM) interface, and /or universal serial bus (universal serial bus, USB) interface, etc.
  • I2C integrated circuit
  • I2S integrated circuit built-in audio
  • PCM pulse code modulation
  • PCM pulse code modulation
  • UART universal asynchronous transmitter
  • MIPI mobile industry processor interface
  • GPIO general-purpose input and output
  • subscriber identity module subscriber identity module
  • SIM subscriber identity module
  • USB universal serial bus
  • the I2C interface is a bidirectional synchronous serial bus, including a serial data line (serial data line, SDA) and a serial clock line (derail clock line, SCL).
  • processor 110 may include multiple sets of I2C buses.
  • the processor 110 can be respectively coupled to the touch sensor 180K, the charger, the flashlight, the camera 193, etc. through different I2C bus interfaces.
  • the processor 110 may be coupled to the touch sensor 180K through the I2C interface, so that the processor 110 and the touch sensor 180K communicate through the I2C bus interface to realize the touch function of the terminal 100 .
  • the I2S interface can be used for audio communication.
  • processor 110 may include multiple sets of I2S buses.
  • the processor 110 may be coupled to the audio module 170 through an I2S bus to implement communication between the processor 110 and the audio module 170 .
  • the audio module 170 can transmit audio signals to the wireless communication module 160 through the I2S interface, so as to realize the function of answering calls through the Bluetooth headset.
  • the PCM interface can also be used for audio communication, sampling, quantizing and encoding the analog signal.
  • the audio module 170 and the wireless communication module 160 may be coupled through a PCM bus interface.
  • the audio module 170 can also transmit audio signals to the wireless communication module 160 through the PCM interface, so as to realize the function of answering calls through the Bluetooth headset. Both the I2S interface and the PCM interface can be used for audio communication.
  • the UART interface is a universal serial data bus used for asynchronous communication.
  • the bus can be a bidirectional communication bus. It converts the data to be transmitted between serial communication and parallel communication.
  • a UART interface is generally used to connect the processor 110 and the wireless communication module 160 .
  • the processor 110 communicates with the Bluetooth module in the wireless communication module 160 through the UART interface to realize the Bluetooth function.
  • the audio module 170 can transmit audio signals to the wireless communication module 160 through the UART interface, so as to realize the function of playing music through the Bluetooth headset.
  • the MIPI interface can be used to connect the processor 110 with peripheral devices such as the display screen 194 and the camera 193 .
  • MIPI interface includes camera serial interface (camera serial interface, CSI), display serial interface (display serial interface, DSI), etc.
  • the processor 110 communicates with the camera 193 through a CSI interface to realize the shooting function of the terminal 100 .
  • the processor 110 communicates with the display screen 194 through the DSI interface to realize the display function of the terminal 100 .
  • the GPIO interface can be configured by software.
  • the GPIO interface can be configured as a control signal or as a data signal.
  • the GPIO interface can be used to connect the processor 110 with the camera 193 , the display screen 194 , the wireless communication module 160 , the audio module 170 , the sensor module 180 and so on.
  • the GPIO interface can also be configured as an I2C interface, I2S interface, UART interface, MIPI interface, etc.
  • the USB interface 130 is an interface conforming to the USB standard specification, specifically, it can be a Mini USB interface, a Micro USB interface, a USB Type C interface, and the like.
  • the USB interface 130 can be used to connect a charger to charge the terminal 100, and can also be used to transmit data between the terminal 100 and peripheral devices. It can also be used to connect headphones and play audio through them. This interface can also be used to connect other electronic devices, such as AR devices.
  • the interface connection relationship between the modules shown in the embodiment of the present invention is only a schematic illustration, and does not constitute a structural limitation of the terminal 100 .
  • the terminal 100 may also adopt different interface connection modes in the foregoing embodiments, or a combination of multiple interface connection modes.
  • the charging management module 140 is configured to receive a charging input from a charger.
  • the charger may be a wireless charger or a wired charger.
  • the charging management module 140 can receive charging input from the wired charger through the USB interface 130 .
  • the charging management module 140 may receive wireless charging input through the wireless charging coil of the terminal 100 . While the charging management module 140 is charging the battery 142 , it can also provide power for electronic devices through the power management module 141 .
  • the power management module 141 is used for connecting the battery 142 , the charging management module 140 and the processor 110 .
  • the power management module 141 receives the input from the battery 142 and/or the charging management module 140 to provide power for the processor 110 , the internal memory 121 , the external memory, the display screen 194 , the camera 193 , and the wireless communication module 160 .
  • the power management module 141 can also be used to monitor parameters such as battery capacity, battery cycle times, and battery health status (leakage, impedance).
  • the power management module 141 may also be disposed in the processor 110 .
  • the power management module 141 and the charging management module 140 can also be set in the same device.
  • the wireless communication function of the terminal 100 can be realized by the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, the modem processor and the baseband processor.
  • Antenna 1 and Antenna 2 are used to transmit and receive electromagnetic wave signals.
  • Each antenna in terminal 100 may be used to cover single or multiple communication frequency bands. Different antennas can also be multiplexed to improve the utilization of the antennas.
  • Antenna 1 can be multiplexed as a diversity antenna of a wireless local area network.
  • the antenna may be used in conjunction with a tuning switch.
  • the mobile communication module 150 can provide wireless communication solutions including 2G/3G/4G/5G applied on the terminal 100 .
  • the mobile communication module 150 may include at least one filter, switch, power amplifier, low noise amplifier (low noise amplifier, LNA) and the like.
  • the mobile communication module 150 can receive electromagnetic waves through the antenna 1, filter and amplify the received electromagnetic waves, and send them to the modem processor for demodulation.
  • the mobile communication module 150 can also amplify the signals modulated by the modem processor, and convert them into electromagnetic waves through the antenna 1 for radiation.
  • at least part of the functional modules of the mobile communication module 150 may be set in the processor 110 .
  • at least part of the functional modules of the mobile communication module 150 and at least part of the modules of the processor 110 may be set in the same device.
  • a modem processor may include a modulator and a demodulator.
  • the modulator is used for modulating 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. Then the demodulator sends the demodulated low-frequency baseband signal to the baseband processor for processing.
  • the low-frequency baseband signal is passed to the application processor after being processed by the baseband processor.
  • the application processor outputs sound signals through audio equipment (not limited to speaker 170A, receiver 170B, etc.), or displays images or videos through display screen 194 .
  • the modem processor may be a stand-alone device.
  • the modem processor may be independent from the processor 110, and be set in the same device as the mobile communication module 150 or other functional modules.
  • the wireless communication module 160 can provide wireless local area networks (wireless local area networks, WLAN) (such as wireless fidelity (Wi-Fi) network), bluetooth (bluetooth, BT), global navigation satellite system, etc. (global navigation satellite system, GNSS), satellite communication module, frequency modulation (frequency modulation, FM), near field communication technology (near field communication, NFC), infrared technology (infrared, IR) and other wireless communication solutions.
  • the wireless communication module 160 may 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 through the antenna 2 for radiation.
  • the satellite communication module can be used to communicate with satellite network equipment.
  • the satellite communication module can communicate with the Beidou network equipment 200, and the satellite communication module can support short message transmission with the Beidou network equipment 200 .
  • 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 (general packet radio service, GPRS), code division multiple access (code division multiple access, CDMA), broadband Code division multiple access (wideband code division multiple access, WCDMA), time division code division multiple access (time-division code division multiple access, TD-SCDMA), long term evolution (long term evolution, LTE), BT, GNSS, WLAN, NFC , FM, and/or IR techniques, etc.
  • GSM global system for mobile communications
  • GPRS general packet radio service
  • code division multiple access code division multiple access
  • CDMA broadband Code division multiple access
  • WCDMA wideband code division multiple access
  • time division code division multiple access time-division code division multiple access
  • TD-SCDMA time-division code division multiple access
  • LTE long
  • the GNSS may include a global positioning system (global positioning system, GPS), a global navigation satellite system (global navigation satellite system, GLONASS), a Beidou navigation satellite system (beidou navigation satellite system, BDS), a quasi-zenith satellite system (quasi -zenith satellite system (QZSS) and/or satellite based augmentation systems (SBAS).
  • GPS global positioning system
  • GLONASS global navigation satellite system
  • Beidou navigation satellite system beidou navigation satellite system
  • BDS Beidou navigation satellite system
  • QZSS quasi-zenith satellite system
  • SBAS satellite based augmentation systems
  • the terminal 100 realizes the display function through the GPU, the display screen 194, and the application processor.
  • the GPU is a microprocessor for image processing, and is connected to the display screen 194 and the application processor. GPUs are 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 change display information.
  • the display screen 194 is used to display images, videos and the like.
  • the 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 or an active matrix organic light emitting diode (active-matrix organic light emitting diode, AMOLED), flexible light-emitting diode (flex light-emitting diode, FLED), Miniled, MicroLed, Micro-oLed, quantum dot light emitting diodes (quantum dot light emitting diodes, QLED), etc.
  • the terminal 100 may include 1 or N display screens 194, where N is a positive integer greater than 1.
  • the terminal 100 can realize the shooting function through the ISP, the camera 193 , the video codec, the GPU, the display screen 194 and the application processor.
  • the ISP is used for processing the data fed back by the camera 193 .
  • the light is transmitted to the photosensitive element of the camera through the lens, and the light signal is converted into an electrical signal, and the photosensitive element of the camera transmits the electrical signal to the ISP for processing, and converts it into an image visible to the naked eye.
  • ISP can also optimize the algorithm for image noise and brightness.
  • ISP can also optimize the exposure, color temperature and other parameters of the shooting scene.
  • the ISP may be located in the camera 193 .
  • Camera 193 is used to capture still images or video.
  • the object generates an optical image through the lens and projects it to the photosensitive element.
  • the photosensitive element may be a charge coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) phototransistor.
  • CMOS complementary metal-oxide-semiconductor
  • the photosensitive element converts the light signal into an electrical signal, and then transmits the electrical signal to the ISP to convert it into a digital image signal.
  • the ISP outputs the digital image signal to the DSP for processing.
  • DSP converts digital image signals into standard RGB, YUV and other image signals.
  • the terminal 100 may include 1 or N cameras 193, where N is a positive integer greater than 1.
  • Digital signal processors are used to process digital signals. In addition to digital image signals, they 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 energy of the frequency point.
  • Video codecs are used to compress or decompress digital video.
  • Terminal 100 may support one or more video codecs.
  • the terminal 100 can play or record videos in various encoding formats, for example: moving picture experts group (moving picture experts group, MPEG) 1, MPEG2, MPEG3, MPEG4, etc.
  • the NPU is a neural-network (NN) computing processor.
  • NN neural-network
  • Applications such as intelligent cognition of the terminal 100 can be implemented through the NPU, such as image recognition, face recognition, speech recognition, text understanding, and the like.
  • the external memory interface 120 may be used to connect an external memory card, such as a Micro SD card, to expand the storage capacity of the terminal 100.
  • the external memory card communicates with the processor 110 through the external memory interface 120 to implement a data storage function. Such as saving music, video and other files in the external memory card.
  • the internal memory 121 may be used to store computer-executable program codes including instructions.
  • the processor 110 executes various functional applications and data processing of the terminal 100 by executing instructions stored in the internal memory 121 .
  • the internal memory 121 may include an area for storing programs and an area for storing data. Wherein, the stored program area can store an operating system, at least one application program required by a function (such as a sound playing function, an image playing function, etc.) and the like.
  • the data storage area can store data created during the use of the terminal 100 (such as audio data, phonebook, etc.) and the like.
  • the internal memory 121 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one magnetic disk storage device, flash memory device, universal flash storage (universal flash storage, UFS) and the like.
  • the terminal 100 can implement audio functions through an audio module 170, a speaker 170A, a receiver 170B, a microphone 170C, an earphone interface 170D, and an application processor. Such as music playback, recording, etc.
  • 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 signal.
  • the audio module 170 may also be used to encode and decode audio signals.
  • the audio module 170 may be set in the processor 110 , or some functional modules of the audio module 170 may be set in the processor 110 .
  • Speaker 170A also referred to as a "horn" is used to convert audio electrical signals into sound signals. Terminal 100 can listen to music through speaker 170A, or listen to hands-free calls.
  • Receiver 170B also called “earpiece” is used to convert audio electrical signals into sound signals.
  • the receiver 170B can be placed close to the human ear to listen to the voice.
  • the microphone 170C also called “microphone” or “microphone” is used to convert sound signals into electrical signals.
  • the user can put his mouth close to the microphone 170C to make a sound, and input the sound signal to the microphone 170C.
  • the terminal 100 may be provided with at least one microphone 170C.
  • the terminal 100 may be provided with two microphones 170C, which may also implement a noise reduction function in addition to collecting sound signals.
  • the terminal 100 can also be equipped with three, four or more microphones 170C to realize sound signal collection, noise reduction, identify sound sources, realize directional recording functions, and the like.
  • the earphone interface 170D is used for connecting wired earphones.
  • the earphone interface 170D can be a 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.
  • OMTP open mobile terminal platform
  • CTIA cellular telecommunications industry association of the USA
  • the pressure sensor 180A is used to sense the pressure signal and convert the pressure signal into an electrical signal.
  • pressure sensor 180A may be disposed on display screen 194 .
  • pressure sensors 180A such as resistive pressure sensors, inductive pressure sensors, and capacitive pressure sensors.
  • a capacitive pressure sensor may be comprised of at least two parallel plates with conductive material.
  • the terminal 100 determines the strength of the pressure from the change in capacitance.
  • the terminal 100 detects the intensity of the touch operation according to the pressure sensor 180A.
  • the terminal 100 may also calculate the touched position according to the detection signal of the pressure sensor 180A.
  • touch operations acting on the same touch position but with different touch operation intensities may correspond to different operation instructions. For example: when a touch operation with a touch operation intensity less than the first pressure threshold acts on the short message application icon, an instruction to view short messages is executed. When a touch operation whose intensity is greater than or equal to the first pressure threshold acts on the icon of the short message application, the instruction of creating a new short message is executed.
  • the gyro sensor 180B can be used to determine the motion posture of the terminal 100 .
  • the angular velocity of the terminal 100 around three axes ie, x, y and z axes
  • the gyro sensor 180B can be used for image stabilization.
  • the gyro sensor 180B detects the shaking angle of the terminal 100, and calculates the distance that the lens module needs to compensate according to the angle, and allows the lens to counteract the shaking of the terminal 100 through reverse movement to achieve anti-shake.
  • the gyro sensor 180B can also be used for navigation and somatosensory game scenes.
  • the air pressure sensor 180C is used to measure air pressure.
  • the terminal 100 calculates the altitude through the air pressure value measured by the air pressure sensor 180C to assist positioning and navigation.
  • the magnetic sensor 180D includes a Hall sensor.
  • the terminal 100 may use the magnetic sensor 180D to detect the opening and closing of the flip holster.
  • the terminal 100 when the terminal 100 is a clamshell machine, the terminal 100 can detect the opening and closing of the clamshell according to the magnetic sensor 180D.
  • features such as automatic unlocking of the flip cover are set.
  • the acceleration sensor 180E can detect the acceleration of the terminal 100 in various directions (generally three axes).
  • the magnitude and direction of gravity can be detected when the terminal 100 is stationary. It can also be used to identify the posture of electronic devices, and can be used in applications such as horizontal and vertical screen switching, pedometers, etc.
  • the distance sensor 180F is used to measure the distance.
  • the terminal 100 can measure the distance by infrared or laser. In some embodiments, when shooting a scene, the terminal 100 may use the distance sensor 180F for distance measurement to achieve fast focusing.
  • Proximity light sensor 180G may include, for example, light emitting diodes (LEDs) and light detectors, such as photodiodes.
  • the light emitting diodes may be infrared light emitting diodes.
  • the terminal 100 emits infrared light through the light emitting diode.
  • the terminal 100 detects infrared reflected light from nearby objects using a photodiode. When sufficient reflected light is detected, it may be determined that there is an object near the terminal 100 . When insufficient reflected light is detected, the terminal 100 may determine that there is no object near the terminal 100 .
  • the terminal 100 can use the proximity light sensor 180G to detect that the user holds the terminal 100 close to the ear to make a call, so as to automatically turn off the screen to save power.
  • the proximity light sensor 180G can also be used in leather case mode, automatic unlock and lock screen in pocket mode.
  • the ambient light sensor 180L is used for sensing ambient light brightness.
  • the terminal 100 may adaptively adjust the brightness of the display screen 194 according to the perceived ambient light brightness.
  • the ambient light sensor 180L can also be used to automatically adjust the white balance when taking pictures.
  • the ambient light sensor 180L can also cooperate with the proximity light sensor 180G to detect whether the terminal 100 is in the pocket, so as to prevent accidental touch.
  • the fingerprint sensor 180H is used to collect fingerprints.
  • the terminal 100 can use the collected fingerprint characteristics to realize fingerprint unlocking, access to the application lock, take pictures with fingerprints, answer incoming calls with fingerprints, and so on.
  • the temperature sensor 180J is used to detect temperature.
  • the terminal 100 uses the temperature detected by the temperature sensor 180J to implement a temperature processing strategy. For example, when the temperature reported by the temperature sensor 180J exceeds the threshold, the terminal 100 executes reducing the performance of a processor located near the temperature sensor 180J, so as to reduce power consumption and implement thermal protection.
  • the terminal 100 when the temperature is lower than another threshold, the terminal 100 heats the battery 142 to avoid abnormal shutdown of the terminal 100 due to low temperature.
  • the terminal 100 boosts the output voltage of the battery 142 to avoid abnormal shutdown caused by low temperature.
  • Touch sensor 180K also known as "touch panel”.
  • the touch sensor 180K can be disposed on the display screen 194, and 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 a touch operation on or near it.
  • the touch sensor can pass the detected touch operation to the application processor to determine the type of touch event.
  • Visual output related to the touch operation can be provided through the display screen 194 .
  • the touch sensor 180K may also be disposed on the surface of the terminal 100 , which is different from the position of the display screen 194 .
  • the bone conduction sensor 180M can acquire vibration signals. In some embodiments, the bone conduction sensor 180M can acquire the vibration signal of the vibrating bone mass of the human voice. The bone conduction sensor 180M can also contact the human pulse and receive the blood pressure beating signal. In some embodiments, the bone conduction sensor 180M can also be disposed in the earphone, combined into a bone conduction earphone.
  • the audio module 170 can analyze the voice signal based on the vibration signal of the vibrating bone mass of the vocal part acquired by the bone conduction sensor 180M, so as to realize the voice function.
  • the application processor can analyze the heart rate information based on the blood pressure beating signal acquired by the bone conduction sensor 180M, so as to realize the heart rate detection function.
  • the keys 190 include a power key, a volume key and the like.
  • the key 190 may be a mechanical key. It can also be a touch button.
  • the terminal 100 may receive key input and generate key signal input related to user settings and function control of the terminal 100 .
  • the motor 191 can generate a vibrating reminder.
  • the motor 191 can be used for incoming call vibration prompts, and can also be used for touch vibration feedback.
  • touch operations applied to different applications may correspond to different vibration feedback effects.
  • the motor 191 may also correspond to different vibration feedback effects for touch operations acting on different areas of the display screen 194 .
  • Different application scenarios for example: time reminder, receiving information, alarm clock, games, etc.
  • the touch vibration feedback effect can also support customization.
  • the indicator 192 can be an indicator light, and can be used to indicate charging status, power change, and can also be used to indicate messages, missed calls, notifications, and the like.
  • the SIM card interface 195 is used for connecting a SIM card.
  • the SIM card can be connected and separated from the terminal 100 by inserting it into the SIM card interface 195 or pulling it out from the SIM card interface 195 .
  • the terminal 100 can support 1 or N SIM card interfaces, where N is a positive integer greater than 1.
  • SIM card interface 195 can support Nano SIM card, Micro SIM card, SIM card etc. Multiple cards can be inserted into the same SIM card interface 195 at the same time. The types of the multiple cards may be the same or different.
  • 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 calling and data communication.
  • the terminal 100 adopts an eSIM, that is, an embedded SIM card.
  • the eSIM card can be embedded in the terminal 100 and cannot be separated from the terminal 100 .
  • a method for transmitting an application layer receipt in the Beidou communication system provided in the embodiment of the present application is introduced below.
  • Fig. 13 shows a schematic flowchart of a method for transmitting an application layer receipt in the Beidou communication system provided in the embodiment of the present application.
  • the application layer receipt transmission method in the Beidou communication system includes the following steps:
  • the sending device sends the first MDCP PDU of the first application layer packet to the receiving device.
  • the header information of the first MDCP PDU includes a successor indication field, and the successor indication field is used to refer to the order of the first MDCP PDU in the first application layer message.
  • the successor indication field is used to refer to the order of the first MDCP PDU in the first application layer message.
  • the receiving device obtains the first application layer packet based on the first MDCP PDU.
  • the receiving device After the receiving device determines that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs in the first application layer message, the receiving device obtains the first application layer message based on the first MDCP PDU.
  • M is a positive integer.
  • the receiving device generates first application layer receipt information.
  • the first application layer receipt information is used to indicate the result of parsing the first application layer packet by the receiving device.
  • the receiving device sends the first application layer receipt information to the sending device.
  • the operation performed by the sending device based on the first application layer receipt information can refer to the foregoing embodiments shown in FIGS. 7-11 , which will not be repeated here.
  • the sending device sends the first MDCP PDU in the first application layer message to the receiving device, specifically including:
  • the sending device uses the first MDCP PDU as the first satellite link control layer service data unit SLC SDU of the SLC layer of the sending device, and sends it from the MDCP layer of the sending device to the SLC layer of the sending device.
  • the sending device splits the first SLC SDU into N SLC PDUs at the SLC layer of the sending device, where N is a positive integer.
  • the N SLC PDUs include the first SLC PDU
  • the frame header information of the first SLC PDU includes the frame total number field and the frame sequence number field.
  • the frame total number field is used to indicate the total number N of SLC PDUs included in the first SLC SDU
  • the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU.
  • the sending device sends N SLC PDUs to the receiving device.
  • the first application layer receipt information is also used to indicate that the receiving device has received all the N SLC PDUs in the first SLC SDU.
  • the sending device can determine all the SLC PDUs corresponding to the application layer message received by the receiving device through the first application layer receipt information.
  • the method before the sending device receives the first application layer receipt information sent by the receiving device, the method further includes: the sending device receives a first confirmation character ACK sent by the receiving device.
  • the first ACK is used to indicate that the receiving device has received all the N SLC PDUs in the first SLC SDU.
  • the method before the sending device receives the first application layer receipt information sent by the receiving device, the method further includes: the sending device receives a second confirmation character ACK sent by the receiving device.
  • the first ACK is used to indicate the frame sequence number of the SLC PDU not received by the receiving device in the first SLC SDU.
  • the sending device retransmits the SLC PDUs not received by the receiving device in the first SLC SDU to the receiving device.
  • the sending device sends N SLC PDUs to the receiving device, which specifically includes: the sending device sends the first SLC PDU from the SLC layer of the sending device to the physical PHY layer as the PHY layer of the sending device Layer's first user frame.
  • the sending device performs physical layer processing on the first user frame to obtain first inbound data.
  • the sending device sends first inbound data to the receiving device.
  • the method before the sending device sends the first MDCP PDU in the first application layer message to the receiving device, the method further includes: the sending device obtains the application layer sent by the sending device at the message data aggregation MDCP layer. The first application layer packet.
  • the sending device takes the first application layer message as an MDCP SDU at the MDCP layer, and splits the MDCP SDU into M MDCP PDUs.
  • M is a positive integer.
  • the M MDCP PDUs include the first MDCP PDU.
  • the method further includes: the sending device sends M MDCP PDUs from the MDCP layer to the SLC layer as M SLC SDUs of the SLC layer, and the M SLC SDUs include the first SLC SDU.
  • the method before the sending device acquires at the MDCP layer the first application layer message delivered by the application layer of the sending device, the method further includes: the sending device acquires original data.
  • the sending device encodes and compresses the original data at the application layer to obtain the first compressed data.
  • the sending device encrypts the first compressed data at the application layer to obtain the first encrypted data.
  • the sending device adds message header information to the first encrypted data header to obtain the first application layer message.
  • the message header information includes a compression indication field and an encryption indication field
  • the compression indication field is used to indicate the encoding compression algorithm used when compressing the original data
  • the encryption indication field is used to indicate the encryption algorithm used when encrypting the first compressed data.
  • the method further includes: the sending device determines that the receiving device fails to parse the first application layer message based on the first application layer receipt information, The sending device retransmits the first application layer message to the receiving device.
  • the sending device determines that the receiving device fails to parse the application layer message, it can send the application layer message again, so as to avoid the situation that the receiving device fails to parse the application layer message due to data errors during transmission.
  • the first application layer receipt information includes a first parsing result, where the first parsing result is used to indicate that the receiving device fails to decrypt the first application layer packet.
  • the method further includes: the sending device negotiates key information with the receiving device.
  • the sending device encrypts the first compressed data based on the negotiated key information to obtain the second encrypted data.
  • the sending device sends the second application layer message including the second encrypted data to the receiving device.
  • the first application layer receipt information includes a second parsing result, where the second parsing result is used to indicate that the receiving device fails to decode and decompress the application layer packet.
  • the method further includes: the sending device negotiates a codebook with the receiving device based on the second parsing result.
  • the sending device encodes and compresses the original data based on the negotiated codebook to obtain second compressed data.
  • the sending device encrypts the second compressed data to obtain third encrypted data.
  • the sending device sends the third application layer packet to the receiving device, where the third application layer packet includes third encrypted data.
  • the above-mentioned sending device is a terminal
  • the receiving device is a Beidou network device.
  • the above-mentioned sending device is a Beidou network device
  • the receiving device is a terminal.
  • the method before the receiving device generates the first application layer receipt information, the method further includes: the receiving device decrypts the first encrypted data in the first application layer message, and obtains the First compress the data.
  • the method further includes: the receiving device decrypts the first The compressed data is decoded and decompressed to obtain the original data.
  • the method before the receiving device generates the first application layer receipt information, the method further includes: the receiving device fails to decrypt the first encrypted data.
  • the receiving device generates first application layer receipt information.
  • the first application layer receipt information includes a first parsing result, and the first parsing result is used to indicate that the receiving device fails to decrypt.
  • the receiving device can generate application layer receipt information for indicating that the receiving device fails to decrypt the application layer message.
  • the method before the receiving device generates the first application layer receipt information, the method further includes: the receiving device fails to decode and decompress the first compressed data.
  • the receiving device generates first application layer receipt information.
  • the first application layer receipt information includes a second parsing result, and the second parsing result is used to indicate that the receiving device fails to decode.
  • the receiving device can generate application layer receipt information for indicating that the receiving device fails to decode the application layer message.
  • the first application layer receipt information includes a third parsing result
  • the third parsing result is used to indicate that the receiving device parses the application layer message successfully.
  • the receiving device can generate application layer receipt information for indicating that the receiving device parses the application layer message successfully.
  • the method further includes: when the receiving device is the Beidou network device 200, sending the original data to the cellular user equipment through the cellular network.
  • the receiving device can forward the data to the user equipment under the cellular network when the parsing is successful.
  • the method before the receiving device receives the first MDCP PDU of the first application layer message sent by the sending device, the method further includes: the receiving device acquires the first inbound data sent by the sending device at the PHY layer .
  • the receiving device performs physical layer processing based on the first inbound data to obtain the first user frame.
  • the receiving device presents the first user frame as the first SLC PDU in the SLC layer of the receiving device from the PHY layer to the SLC layer of the receiving device.
  • the method further includes: the receiving device receives X number of SLC PDUs in the first SLC SDU sent by the sending device, where X is a positive integer.
  • the X SLC PDUs include the first SLC PDU
  • the frame header information of the first SLC PDU includes the frame total number field and the frame sequence number field.
  • the frame total number field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and N is a positive integer, 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 receiving device When X is less than N, the receiving device sends a second ACK to the sending device, wherein the second ACK is used to indicate the frame sequence number of the SLC PDU not received by the receiving device in the first SLC SDU.
  • the receiving device can notify the sending device to retransmit the lost SLC PDU.
  • the method further includes: when X is equal to N, the receiving device converts the X SLC PDUs at the SLC layer Splicing into the first SLC SDU, and reporting the first SLC SDU as the first MDCP PDU of the MDCP layer from the SLC layer of the receiving device to the MDCP layer of the receiving device.
  • the method further includes: when X is equal to N, the receiving device sends the first ACK to the sending device, Wherein, the first ACK is used to indicate that the receiving device has received all the N SLC PDUs in the first SLC SDU.
  • the receiving device obtains the application layer message based on the first MDCP PDU, Specifically include: the receiving device splices M MDCP PDUs at the MDCP layer to obtain an MDCP SDU, and reports the MDCP SDU as an application layer message from the MDCP layer to the application layer.
  • the receiving device sends the first application layer receipt information to the sending device, which specifically includes: the receiving device sends the first application layer receipt information from the application layer of the receiving device to the receiving device through a preset interface. SLC layer.
  • the receiving device After adding frame header information to the first application layer receipt information at the SLC layer, the receiving device sends the first application layer receipt information added with frame header information to the physical layer to obtain a receipt frame.
  • the frame header information includes a frame type field, and the frame type field is used to indicate the frame type of the user frame.
  • the receiving device sends the acknowledgment frame to the sending device.
  • the receiving device sends the first application layer receipt information to the sending device, specifically including:
  • the receiving device encapsulates the first application layer receipt information into an application layer receipt message, and sends the application layer receipt message to the sending device,
  • the above-mentioned sending device is a terminal
  • the receiving device is a Beidou network device.
  • the above-mentioned sending device is a Beidou network device
  • the receiving device is a terminal.
  • the embodiment of the present application can divide the functional modules of the terminal 100 and the Beidou network device 200 according to the above-mentioned 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 middle.
  • the above-mentioned integrated modules can be implemented in the form of hardware or in the form of software function modules. It should be noted that the division of modules in the embodiment of the present application is schematic, and is only a logical function division, and there may be other division methods in actual implementation.
  • FIG. 14 is a schematic structural diagram of a communication device 1400 provided by an embodiment of the present application.
  • the communication device 1400 may be the terminal 100 in the foregoing embodiments.
  • the communication device 1400 may be a chip/chip system, for example, a Beidou communication chip.
  • the communication device 1400 may include a transceiver unit 1410 and a processing unit 1420 .
  • the transceiver unit 1410 may be configured to send the first MDCP PDU in the first application layer message to the Beidou network device 200.
  • the header information of the first MDCP PDU includes a successor indication field.
  • the successor indication field is used to indicate the order of the first MDCP PDU in the first application layer message.
  • the transceiver unit 1410 is configured to receive the first application layer receipt information returned by the Beidou network device 200 when the first MDCP PDU is the last MDCP PDU in the first application layer message, and the first application layer receipt information is used to indicate The Beidou network device 200 parses the result of the first application layer message.
  • the processing unit 1420 may be configured to generate a first application layer packet.
  • the transceiver unit 1410 may be configured to receive the first MDCP PDU.
  • the header information of the first MDCP PDU includes a successor indication field.
  • the successor indication field is used to indicate the order of the first MDCP PDU in the first application layer message.
  • the processing unit 1420 may be configured to obtain the first application layer message based on the first MDCP PDU after determining that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs in the first application layer message; wherein, M is a positive integer.
  • the processing unit 1420 may be configured to generate first application layer receipt information, where the first application layer receipt information is used to indicate a result of the terminal 100 parsing the first application layer packet.
  • the transceiver unit 1410 may be configured to send the first application layer receipt information to the Beidou network device 200 .
  • the transceiver unit 1410 may also be configured to perform the functional steps related to sending and receiving performed by the terminal 100 in the method embodiment shown in FIG. 13 above.
  • processing unit 1420 may also be configured to execute functional steps related to protocol parsing and encapsulation and calculation determination performed by the terminal 100 in the method embodiment shown in FIG. 13 above.
  • the communication device 1200 in this design can correspondingly perform the method steps performed by the terminal 100 in the foregoing embodiments, and for the sake of brevity, details are not repeated here.
  • FIG. 15 is a schematic structural diagram of a communication device 1500 provided in an embodiment of the present application.
  • the communication apparatus 1500 may be the Beidou network device 200 in the foregoing embodiments.
  • the communication device 1500 can be a specific network element in the Beidou network equipment 200, for example, one or more network elements in the Beidou ground transceiver station 22, the Beidou central station 23, and the Beidou short message fusion communication platform 24 The combination.
  • the communication device 1500 may include a transceiver unit 1510 and a processing unit 1520 .
  • the transceiver unit 1510 may be configured to receive the first MDCP PDU.
  • the header information of the first MDCP PDU includes a follow-up indication field.
  • the successor indication field is used to indicate the order of the first MDCP PDU in the first application layer message.
  • the processing unit 1520 may be configured to obtain the first application layer message based on the first MDCP PDU after determining that the first MDCP PDU is the last MDCP PDU among the M MDCP PDUs in the first application layer message; wherein, M is a positive integer.
  • the processing unit 1520 may be configured to generate first application layer receipt information, where the first application layer receipt information is used to indicate the result of the Beidou network device 200 parsing the first application layer message.
  • the transceiver unit 1510 is configured to send the first application layer receipt information to the terminal 100 .
  • the transceiver unit 1510 may be configured to send the first MDCP PDU in the first application layer packet to the terminal 100.
  • the header information of the first MDCP PDU includes a successor indication field.
  • the successor indication field is used to indicate the order of the first MDCP PDU in the first application layer message.
  • the transceiver unit 1510 is configured to receive the first application layer receipt information returned by the terminal 100 when the first MDCP PDU is the last MDCP PDU in the first application layer message, and the first application layer receipt information is used to indicate that the terminal 100 The result of parsing the first application layer packet.
  • the processing unit 1520 may be configured to generate a first application layer packet.
  • the transceiver unit 1510 may also be configured to perform the functional steps related to sending and receiving performed by the Beidou network device 200 in the method embodiment shown in FIG. 13 above.
  • the processing unit 1520 may also be configured to execute functional steps related to protocol parsing and encapsulation and calculation determination performed by the Beidou network device 200 in the method embodiment shown in the above image 13 .
  • the communication device 1500 in this design can correspondingly perform the method steps performed by the Beidou network device 200 in the foregoing embodiments, and for the sake of brevity, details are not repeated here.
  • the terminal 100 and the Beidou network device 200 of the embodiment of the present application have been introduced above. It should be understood that any product that has the functions of the terminal 100 described in FIG. Products of any form with functions fall within the scope of protection of the embodiments of the present application.
  • the terminal 100 described in the embodiment of the present application may be implemented by a general bus architecture.
  • FIG. 16 is a schematic structural diagram of a communication device 1600 provided by an embodiment of the present application.
  • the communication device 1600 may be the terminal 100, or a device therein.
  • the communication device 1600 includes a processor 1601 and a transceiver 1602 internally connected and communicating with the processor.
  • the processor 1601 is a general purpose processor or a special purpose processor or the like.
  • it may be a baseband processor or a central processing unit for satellite communications.
  • the baseband processor of satellite communication can be used to process satellite communication protocols and satellite communication data
  • the central processing unit can be used to control communication devices (such as baseband chips, terminals, terminal chips, etc.), execute computer programs, and process computer Program data.
  • the transceiver 1602 may be called a transceiver unit, a transceiver, or a transceiver circuit, etc., and is used to implement a transceiver function.
  • the transceiver 1602 may include a receiver and a transmitter, and the receiver may be called a receiver or a receiving circuit for realizing a receiving function; the transmitter may be called a transmitter or a sending circuit for realizing a sending function.
  • the communication device 1600 may further include an antenna 1603 and/or a radio frequency unit (not shown in the figure).
  • 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 remote or distributed.
  • the communication device 1600 may include one or more memories 1604, on which instructions may be stored.
  • the instructions may be computer programs, and the computer programs may be run on the communication device 1600, so that the communication device 1600 executes the above-mentioned Methods described in the Methods Examples.
  • data may also be stored in the memory 1604 .
  • the communication device 1600 and the memory 1604 can be set separately or integrated together.
  • processor 1601, the transceiver 1602, and the memory 1604 may be connected through a communication bus.
  • the communication device 1600 can be used to perform the functions of the terminal 100 in the foregoing embodiments: the processor 1601 can be used to perform the functions related to protocol analysis and encapsulation and operation determination performed by the terminal 100 in the embodiment shown in FIG. 13 Steps and/or other processes for the technology described herein; the transceiver 1602 may be used to perform the functional steps related to sending and receiving performed by the terminal 100 in the embodiment shown in FIG. 13 and/or for the steps described herein Other processes of technology.
  • the processor 1601 may include a transceiver for implementing receiving and sending functions.
  • the transceiver may be a transceiver circuit, or an interface, or an interface circuit.
  • the transceiver circuits, interfaces or interface circuits for realizing the functions of receiving and sending can be separated or integrated together.
  • the above-mentioned transceiver circuit, interface or interface circuit may be used for reading and writing code/data, or the above-mentioned transceiver circuit, interface or interface circuit may be used for signal transmission or transfer.
  • the processor 1601 may store instructions, which may be computer programs, and the computer programs run on the processor 1601 to enable the communication device 1600 to perform the method steps performed by the terminal 100 in the above method embodiments.
  • the computer program may be fixed in the processor 1600, and in this case, the processor 1601 may be implemented by hardware.
  • the communication device 1600 may include a circuit, and the circuit may implement the function of sending or receiving or communicating in the foregoing method embodiments.
  • the processors and transceivers described in this application can be implemented in integrated circuits (integrated circuits, ICs), analog ICs, radio frequency integrated circuits (RFICs), mixed-signal ICs, application specific integrated circuits (ASICs), printed circuit boards ( printed circuit board, PCB), electronic equipment, etc.
  • the processor and transceiver can also be fabricated using various IC process technologies, such as complementary metal oxide semiconductor (CMOS), 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.
  • CMOS complementary metal oxide semiconductor
  • NMOS nMetal-oxide-semiconductor
  • PMOS P-type Metal oxide semiconductor
  • BJT bipolar junction transistor
  • BiCMOS bipolar CMOS
  • SiGe silicon germanium
  • GaAs gallium arsenide
  • Communications apparatus 1600 may be a stand-alone device or may be part of a larger device.
  • the communication device 1600 may be:
  • a set of one or more ICs may also include storage components for storing data and computer programs;
  • ASIC such as modem (Modem);
  • any network element for example, Beidou ground transceiver station 22, Beidou central station 23, Beidou short message fusion communication platform 24
  • Beidou network equipment 200 described in the embodiment of the application can Implemented by a generic bus architecture.
  • FIG. 17 is a schematic structural diagram of a communication device 1700 provided by an embodiment of the present application.
  • the communication device 1700 may be the BeiDou network device 200, or a device therein.
  • the communication device 1700 includes a processor 1701 and a transceiver 1702 internally connected and communicating with the processor.
  • the processor 1701 is a general purpose processor or a special purpose processor or the like. For example, it may be a baseband processor or a central processing unit for satellite communications.
  • the baseband processor of the satellite communication can be used to process the satellite communication protocol and satellite communication data, and the central processing unit can be used to control the communication device (eg, baseband chip, etc.), execute the computer program, and process the data of the computer program.
  • the transceiver 1702 may be called a transceiver unit, a transceiver, or a transceiver circuit, etc., and is used to implement a transceiver function.
  • the transceiver 1702 may include a receiver and a transmitter, and the receiver may be called a receiver or a receiving circuit for realizing a receiving function; the transmitter may be called a transmitter or a sending circuit for realizing a sending function.
  • the communication device 1700 may further include an antenna 1703 and/or a radio frequency unit (not shown in the figure).
  • the antenna 1703 and/or the radio frequency unit may be located inside the communication device 1700, or may be separated from the communication device 1700, that is, the antenna 1703 and/or the radio frequency unit may be remote or distributed.
  • the communication device 1700 may include one or more memories 1704, on which instructions may be stored, the instructions may be computer programs, and the computer programs may be run on the communication device 1700, so that the communication device 1700 executes the above-mentioned Methods described in the Methods Examples.
  • data may also be stored in the memory 1704 .
  • the communication device 1700 and the memory 1704 can be set separately or integrated together.
  • the processor 1701, the transceiver 1702, and the memory 1704 may be connected through a communication bus.
  • the communication device 1700 can be used to perform the functions of the Beidou network device 200 in the foregoing embodiments: the processor 1701 can be used to perform the related protocol parsing and encapsulation performed by the Beidou network device 200 in the embodiment shown in FIG. 13 and The functional steps determined by the calculation and/or other processes used in the technology described herein; the transceiver 1702 can be used to perform the functional steps and/or Other procedures for the techniques described herein.
  • the processor 1701 may include a transceiver for implementing receiving and sending functions.
  • the transceiver may be a transceiver circuit, or an interface, or an interface circuit.
  • the transceiver circuits, interfaces or interface circuits for realizing the functions of receiving and sending can be separated or integrated together.
  • the above-mentioned transceiver circuit, interface or interface circuit may be used for reading and writing code/data, or the above-mentioned transceiver circuit, interface or interface circuit may be used for signal transmission or transfer.
  • the processor 1701 may store instructions, which may be computer programs, and the computer programs run on the processor 1701 to enable the communication device 1700 to execute the methods performed by the Beidou network device 200 in the above method embodiments step.
  • the computer program may be fixed in the processor 1701, and in this case, the processor 1701 may be implemented by hardware.
  • the embodiment of the present application also provides a computer-readable storage medium, where computer program code is stored in the computer-readable storage medium, and when the above-mentioned processor executes the computer program code, the communication device executes the method in any of the above-mentioned embodiments .
  • An embodiment of the present application further provides a computer program product, which, when the computer program product is run on a computer, causes the computer to execute the method in any one of the foregoing embodiments.
  • the embodiment of the present application also provides a communication device, which can exist in the product form of a chip.
  • 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 performs the aforementioned The method in any of the examples.
  • the embodiment of the present application also 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 foregoing embodiments.
  • This application fully introduces the communication function of short messages in the Beidou communication system. It is understandable that other satellite systems may also have communication functions that support short messages. Therefore, it is not limited to the Beidou communication system. If other satellite systems also support the short message communication function, the method introduced in this application is also applicable to the communication of other satellite systems.
  • the steps of the methods or algorithms described in connection with the disclosure of this application can be implemented in the form of hardware, or can be implemented in the form of a processor executing software instructions.
  • Software instructions can be composed of corresponding software modules, and software modules can be stored in random access memory (Random Access Memory, RAM), flash memory, erasable programmable read-only memory (Erasable Programmable ROM, EPROM), electrically erasable Programmable read-only memory (Electrically EPROM, EEPROM), registers, hard disk, removable hard disk, CD-ROM, or any other form of storage medium known in the art.
  • An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium.
  • the storage medium may also be a component of the processor.
  • the processor and storage medium can be located in the ASIC.
  • the ASIC may be located in the core network interface device.
  • the processor and the storage medium may also exist in the core network interface device as discrete components.
  • Computer-readable media includes both computer-readable storage media and communication media including any medium that facilitates transfer of a computer program from one place to another.
  • a storage media may be any available media that can be accessed by a general purpose or special purpose computer.

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Abstract

本申请涉及卫星通信技术领域，并公开了一种应用层回执传输方法、系统及装置。接收设备可以在接收到发送设备发送的应用层报文后，解析应用层报文并根据解析应用层报文的结果生成相应的应用层回执信息。接收设备可以将应用层回执信息发送至发送设备，发送设备可以基于应用层回执信息确认接收设备解析应用层报文的情况(例如解析成功，解析失败)。这样，可以建立可信的报文传输机制，保证发送设备可以得到接收设备解析应用层报文的情况。

Description

一种北斗通信系统中应用层回执传输方法、系统及装置
本申请要求于2021年07月31日提交中国专利局、申请号为202110877181.6、申请名称为“一种北斗通信系统中应用层回执传输方法、系统及装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及卫星通信领域，尤其涉及一种北斗通信系统中应用层回执传输方法、系统及装置。
背景技术
北斗卫星导航系统是集定位、授时、通信于一体的重大基础设施。北斗短报文通信业务是北斗卫星导航系统区别于GPS、GLONASS、GALILEO等其他全球导航系统的特色之一。北斗短报文通信业务特别适用于在海洋、沙漠、草原、无人区等移动通信未覆盖、或覆盖不了、或通信系统被破坏的区域进行通信。北斗三号卫星的短报文系统对短报文技术体制进行了升级将北斗短报文业务的通信系统一些必要的资源开放给民用，针对民用业务和设备特性，需要依据北斗短报文业务的通信系统的特性设计通信协议。
目前，北斗短报文业务的通信系统采用卫星链路控制层(satellitelinkcontrolprotocol，SLC)的反馈机制来确保传输的数据包不丢失。即，接收设备在接收窗结束时可以向发送设备发送SLC层的确认字符(acknowledge character，ACK)，发送设备可以基于ACK确定接收设备在SLC层的数据包接收情况。发送设备可以在确定出接收设备未接收到完整的数据包时重传数据。但是，这样只能保证发送设备可以确认接收设备在SLC层接收数据包的情况，却不能确认在应用层解析数据包的情况。
发明内容
本申请提供了一种北斗通信系统中应用层回执传输方法、系统及相关装置，实现了发送设备和接收设备之间可以建立可信的报文传输机制，保证接收设备可以解析应用层报文得到原始数据，确保发送设备和接收设备之间的正常通信。
第一方面，本申请提供了一种北斗通信系统中应用层回执传输方法，包括：
发送设备发送第一应用层报文中的第一消息数据汇聚层协议数据单元MDCP PDU给接收设备。其中，第一MDCP PDU的包头信息包括后继指示字段。后继指示字段用于指示第一MDCP PDU在第一应用层报文中的顺序。
当第一MDCP PDU为第一应用层报文中的最后一个MDCP PDU时，发送设备接收到接收设备发送的第一应用层回执信息。其中，第一应用层回执信息用于指示接收设备解析第一应用层报文的结果。
通过本申请提供的一种北斗通信系统中应用层回执传输方法，接收设备可以在得到发送设备发送的应用层报文后，基于解析应用层报文的结果生成应用层回执信息。接收设备可以将应用层回执信息发送给发送设备，发送设备可以基于应用层回执信息确定接收设备解析应用层报文的情况。
这样，发送设备可以确认接收设备是否得到了发送设备的原始数据。发送设备可以明确 数据的发送情况。
在一种可能的实现方式中，发送设备发送第一应用层报文中的第一MDCP PDU给接收设备，具体包括：
发送设备将第一MDCP PDU作为发送设备的SLC层的第一卫星链路控制层服务数据单元SLC SDU，从发送设备的MDCP层下发至发送设备的SLC层。
发送设备在发送设备的SLC层将第一SLC SDU拆分成N个卫星链路控制层协议数据单元SLC PDU，N为正整数。其中，N个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括帧总数字段和帧序号字段。帧总数字段用于指示第一SLC SDU中包括的SLC PDU的总数量N，帧序号字段用于指示第一SLC PDU在第一SLC SDU中的帧序号。
发送设备将N个SLC PDU发送给接收设备。
具体内容，发送设备将第一MDCP PDU下发至SLC层，作为SLC层的第一SLC SDU并将第一SLC SDU拆分成N个SCL PDU的过程，可以参考图7所示实施例，在此不再赘述。
在一种可能的实现方式中，第一应用层回执信息还用于指示接收设备已收齐第一SLC SDU中的N个SLC PDU。这样，发送设备可以通过第一应用层回执信息判定出接收设备接收到应用层报文对应的所有SLC PDU。
在一种可能的实现方式中，发送设备接收到接收设备发送的第一应用层回执信息之前，方法还包括：发送设备接收到接收设备发送的第一确认字符ACK。其中，第一ACK用于指示接收设备已收齐第一SLC SDU中的N个SLC PDU。
在一种可能的实现方式中，发送设备接收到接收设备发送的第一应用层回执信息之前，方法还包括：发送设备接收到接收设备发送的第二确认字符ACK。其中，第二ACK用于指示第一SLC SDU中接收设备未接收到的SLC PDU的帧序号。
发送设备重传第一SLC SDU中接收设备未接收到的SLC PDU给接收设备。
这样，可以保证接收设备可以得到完整的应用层报文。
在一种可能的实现方式中，在发送设备接收到接收设备发送的第一确认字符ACK之前，方法还包括：发送设备接收到接收设备发送的第二确认字符ACK。其中，第二ACK用于指示第一SLC SDU中接收设备未接收到的SLC PDU的帧序号。
发送设备重传第一SLC SDU中接收设备未接收到的SLC PDU给接收设备。
这样，可以保证接收设备可以得到完整的应用层报文。
在一种可能的实现方式中，发送设备将N个SLC PDU发送给接收设备，具体包括：发送设备将所第一SLC PDU从发送设备的SLC层下发至物理PHY层，作为发送设备的PHY层的第一用户帧。
发送设备针对第一用户帧进行物理层处理得到第一入站数据。
发送设备将第一入站数据发送给接收设备。
在一种可能的实现方式中，发送设备发送第一应用层报文中的第一MDCP PDU给接收设 备之前，方法还包括：发送设备在消息数据汇聚MDCP层获取到发送设备的应用层下发的第一应用层报文。
发送设备在MDCP层将第一应用层报文作为MDCP SDU，并将MDCP SDU拆分成M个MDCP PDU。其中，M为正整数。M个MDCP PDU中包括第一MDCP PDU。
在一种可能的实现方式中，方法还包括：发送设备将M个MDCP PDU从MDCP层下发至SLC层，作为SLC层的M个SLC SDU，M个SLC SDU包括第一SLC SDU。
在一种可能的实现方式中，在发送设备在MDCP层获取到发送设备的应用层下发的第一应用层报文之前，方法还包括：发送设备获取原始数据。
发送设备在应用层将原始数据，进行编码压缩得到第一压缩数据。
发送设备在应用层将第一压缩数据进行加密得到第一加密后数据。
发送设备在第一加密后数据头部加上报文头信息，得到第一应用层报文。其中，报文头信息包括压缩指示字段和加密指示字段，压缩指示字段用于指示对原始数据压缩时使用的编码压缩算法，加密指示字段用于指示对第一压缩数据加密时使用的加密算法。
在一种可能的实现方式中，发送设备接收到接收设备发送的第一应用层回执信息之后，方法还包括：
发送设备基于第一应用层回执信息确定接收设备解析第一应用层报文失败，发送设备向接收设备重传第一应用层报文。
这样，发送设备在确定接收设备解析应用层报文失败时，可以再次发送应用层报文，避免因为传输过程中的数据错误导致接收设备解析应用层报文失败的情形。
在一种可能的实现方式中，第一应用层回执信息包括第一解析结果，其中，第一解析结果用于指示接收设备解密第一应用层报文失败。发送设备接收到接收设备发送的第一应用层回执信息之后，方法还包括：
发送设备与接收设备协商密钥信息。
发送设备基于协商后的密钥信息加密第一压缩数据得到第二加密后数据。
发送设备将包括有第二加密后数据的第二应用层报文发送到接收设备。
在一种可能的实现方式中，第一应用层回执信息包括第二解析结果，其中，第二解析结果用于指示接收设备解码解压缩应用层报文失败。发送设备接收到接收设备发送的第一应用层回执信息之后，方法还包括：
发送设备基于第二解析结果和接收设备协商码本。
发送设备基于协商后的码本编码压缩原始数据得到第二压缩数据。
发送设备将第二压缩数据加密，得到第三加密后数据。
发送设备将第三应用层报文发送给接收设备，第三应用层报文包括第三加密后数据。
在一种可能的实现方式中，上述发送设备为终端，并且接收设备为北斗网络设备。
在一种可能的实现方式中，上述发送设备为北斗网络设备，并且接收设备为终端。
第二方面，本申请提供了一种北斗通信系统中应用层回执传输方法，包括：
接收设备接收到发送设备发送的第一应用层报文的第一MDCP PDU。其中，第一MDCP PDU的包头信息包括后继指示字段。后继指示字段用于指示第一MDCP PDU在第一应用层报文中的顺序。
在接收设备确定出第一MDCP PDU为第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，接收设备基于第一MDCP PDU得到第一应用层报文。其中，M为正整数。
接收设备生成第一应用层回执信息，第一应用层回执信息用于指示接收设备解析第一应用层报文的结果。
接收设备将第一应用层回执信息发送至发送设备。
在一种可能的实现方式中，在接收设备生成第一应用层回执信息之前，方法还包括：接收设备对第一应用层报文中的第一加密后数据进行解密，并在解密成功后得到第一压缩数据。
在一种可能的实现方式中，在接收设备对第一应用层报文中的第一加密后数据进行解密，并在解密成功后得到第一压缩数据之后，方法还包括：接收设备对第一压缩数据进行解码解压缩得到原始数据。
在一种可能的实现方式中，在接收设备生成第一应用层回执信息之前，方法还包括：接收设备对第一加密后数据解密失败。
接收设备生成第一应用层回执信息。其中，第一应用层回执信息包括第一解析结果，第一解析结果用于指示接收设备解密失败。
在一种可能的实现方式中，在接收设备生成第一应用层回执信息之前，方法还包括：接收设备对第一压缩数据解码解压缩失败。
接收设备生成第一应用层回执信息。其中，第一应用层回执信息包括第二解析结果，第二解析结果用于指示接收设备解码失败。
在一种可能的实现方式中，第一应用层回执信息包括第三解析结果，第三解析结果用于指示接收设备解析应用层报文成功。
在一种可能的实现方式中，方法还包括：接收设备为北斗网络设备200时，可以将原始数据通过蜂窝网络发送给蜂窝用户设备。
在一种可能的实现方式中，接收设备接收到发送设备发送的第一应用层报文的第一MDCP PDU之前，方法还包括：接收设备在PHY层获取到发送设备发送的第一入站数据。
接收设备基于第一入站数据执行物理层处理得到第一用户帧。
接收设备将第一用户帧作为接收设备的SLC层中的第一SLC PDU，从PHY层呈递给接收设备的SLC层。
在一种可能的实现方式中，在接收设备将第一用户帧作为接收设备的SLC层中的第一 SLC PDU，从PHY层呈递给接收设备的SLC层之后，方法还包括：接收设备接收到发送设备发送的第一SLC SDU中的X个SLC PDU，X为正整数。其中，X个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括帧总数字段和帧序号字段。帧总数字段用于指示第一SLC SDU中包括SLC PDU的总数量N，N为正整数，帧序号字段用于指示第一SLC PDU在第一SLC SDU中的帧序号。
当X小于N时，接收设备向发送设备发送第二ACK，其中，第二ACK用于指示第一SLC SDU中接收设备未接收到的SLC PDU的帧序号。
在一种可能的实现方式中，当接收设备接收到发送设备发送的第一SLC SDU中的X个SLC PDU后，方法还包括：当X等于N时，接收设备在SLC层将X个SLC PDU拼接成第一SLC SDU，并将第一SLC SDU作为MDCP层的第一MDCP PDU从接收设备的SLC层上报给接收设备的MDCP层。
在一种可能的实现方式中，当接收设备接收到发送设备发送的第一SLC SDU中的X个SLC PDU后，方法还包括：当X等于N时，接收设备向发送设备发送第一ACK，其中，第一ACK用于指示接收设备已收齐第一SLC SDU中的N个SLC PDU。
在一种可能的实现方式中，在接收设备确定出第一MDCP PDU为应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，接收设备基于第一MDCP PDU得到应用层报文，具体包括：接收设备在MDCP层将M个MDCP PDU拼接得到MDCP SDU，并将MDCP SDU作为应用层报文从MDCP层上报给应用层。
在一种可能的实现方式中，接收设备将第一应用层回执信息发送至发送设备，具体包括：接收设备将第一应用层回执信息从接收设备的应用层经过预设接口发送至接收设备的SLC层。
接收设备在SLC层给第一应用层回执信息添加帧头信息后，将添加了帧头信息的第一应用层回执信息下发至物理层，得到回执帧。其中，帧头信息包括帧类型字段，帧类型字段用于指示用户帧的帧类型。
接收设备将回执帧发送至发送设备。
在一种可能的实现方式中，上述发送设备为终端，并且接收设备为北斗网络设备。
在一种可能的实现方式中，上述发送设备为北斗网络设备，并且接收设备为终端。
第三方面，本申请提供了一种北斗通信系统，包括：终端和北斗网络设备；其中：
发送设备，用于向接收设备发送第一应用层报文的第一MDCP PDU。接收设备，用于接收第一MDCP PDU。接收设备，还用于在确定出第一MDCP PDU为第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，基于第一MDCP PDU得到第一应用层报文。其中，M为正整数。接收设备，还用于生成第一应用层回执信息，第一应用层回执信息用于指示接收设备解析第一应用层报文的结果。接收设备，还用于向发送设备发送第一应用层回执信息。发送设备，用于接收第一应用层回执信息。
在一种可能的实现方式中，发送设备还可以执行上述第一方面中任一种可能的实现方式中的方法。
在一种可能的实现方式中，接收设备还可以执行上述第一方面中任一种可能的实现方式 中的方法。
在一种可能的实现方式中，上述发送设备为终端，并且接收设备为北斗网络设备。
在一种可能的实现方式中，上述发送设备为北斗网络设备，并且接收设备为终端。
第四方面，本申请提供了一种通信装置，包括一个或多个处理器、一个或多个存储器和收发器。收发器、该一个或多个存储器与一个或多个处理器耦合，一个或多个存储器用于存储计算机程序代码，计算机程序代码包括计算机指令，当一个或多个处理器执行计算机指令时，使得通信装置执行上述第一方面或第二方面任一项可能的实现方式中的方法。
其中，该通信装置可以为终端或其他产品形态的设备。
第五方面，本申请提供了一种通信装置，包括一个或多个处理器、一个或多个存储器和收发器。收发器、该一个或多个存储器与一个或多个处理器耦合，一个或多个存储器用于存储计算机程序代码，计算机程序代码包括计算机指令，当一个或多个处理器执行计算机指令时，使得通信装置执行上述第一方面或第二方面任一项可能的实现方式中的方法。
其中，该通信装置可以为北斗网络设备，或北斗网络设备中的任一网元或多个网元的组合。
第六方面，本申请提供了一种计算机存储介质，包括计算机指令，当计算机指令在计算机上运行时，使得计算机执行上述第一方面任一项可能的实现方式中的方法。
第七方面，本申请提供了一种计算机存储介质，包括计算机指令，当计算机指令在计算机上运行时，使得计算机执行上述第二方面任一项可能的实现方式中的方法。
第八方面，本申请提供了一种计算机程序产品，当计算机程序产品在计算机上运行时，使得计算机执行上述第一方面任一项可能的实现方式中的方法。
第九方面，本申请提供了一种计算机程序产品，当计算机程序产品在计算机上运行时，使得计算机执行上述第二方面任一项可能的实现方式中的方法。
第十方面，本申请提供了一种芯片或芯片系统，应用于终端，包括处理电路和接口电路，接口电路用于接收代码指令并传输至所述处理电路，处理电路用于运行所述代码指令以执行上述第一方面或第二方面任一项可能的实现方式中的方法。
附图说明
图1A为本申请实施例提供的一种北斗通信系统示意图；
图1B为本申请实施例提供的一种北斗通信系统示意图；
图1C为本申请实施例提供的一种北斗通信系统示意图；
图2A-图2B为本申请实施例提供的一种北斗通信系统中的入站协议示意图；
图3A-图3B为本申请实施例提供的一种北斗通信系统中的出站协议示意图；
图4为本申请实施例提供的一种北斗通信系统中的ACK处理流程示意图；
图5为本申请实施例提供的一种北斗通信系统中的协议处理流程示意图；
图6A为本申请实施例提供的一种北斗通信系统中的入站传输示意图；
图6B为本申请实施例提供的一种北斗通信系统中的出站传输示意图；
图7为本申请实施例提供的一种北斗通信系统中的应用层回执机制示意图；
图8为本申请实施例提供的一种北斗通信系统中的应用层报文示意图；
图9为本申请实施例提供的一种北斗通信系统中的回执帧示意图；
图10为本申请实施例提供的一种北斗通信系统中的回执帧示意图；
图11为本申请实施例提供的一种北斗通信系统中的应用层回执机制示意图；
图12为本申请实施例提供的一种硬件结构示意图；
图13为本申请实施例提供的一种北斗通信系统中应用层回执传输方法的流程示意图；
图14为本申请实施例提供的一种通信装置的结构示意图；
图15为本申请实施例提供的另一种通信装置的结构示意图；
图16为本申请实施例提供的另一种通信装置的结构示意图；
图17为本申请实施例提供的另一种通信装置的结构示意图。
具体实施方式
下面将结合附图对本申请实施例中的技术方案进行清楚、详尽地描述。其中，在本申请实施例的描述中，除非另有说明，“/”表示或的意思，例如，A/B可以表示A或B；文本中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。
以下，术语“第一”、“第二”仅用于描述目的，而不能理解为暗示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征，在本申请实施例的描述中，除非另有说明，“多个”的含义是两个或两个以上。
下面介绍本申请实施例提供的一种北斗通信系统10。
如图1A所示，北斗通信系统10可以包括但不限于终端100、北斗短报文卫星21、北斗网络设备200、短消息中心25和终端300等等。可选的，该北斗通信系统10还可以包括紧急救援平台26、紧急救援中心27。
其中，北斗网络的终端100可以向蜂窝网络的终端300发送短报文信息。具体的，终端100可以先发送短报文信息给北斗短报文卫星21，北斗短报文卫星21只进行中继，可以直接将终端100发送的短报文信息转发给地面的北斗网络设备200。北斗网络设备200可以根据北斗通信协议解析卫星转发的短报文信息，并将从短报文信息中解析出的报文内容转发给短消息中心(short message service center，SMSC)25。短消息中心25可以通过传统的蜂窝通信网络，将报文内容转发给终端300。其中，北斗网络设备200也可以将终端100发送的紧急救援类型的报文，通过紧急救援平台26发送给紧急救援中心27。
蜂窝网络的终端300(可以称为蜂窝用户设备)也可以向北斗网络的终端100发送短报文信息。终端300可以通过传统的蜂窝通信网络(又称为蜂窝网络)，将短消息发送给短消息中心25。短消息中心25可以将终端300的短消息转发给北斗网络设备200。北斗网络设备200可以将终端300的短消息通过北斗短报文卫星21中继发送给终端100。
其中，上述北斗网络设备200可以包括北斗地面发送/接收站22、北斗中心站23和北斗 短报文融合通信平台24。其中，北斗地面发送/接收站22可以包括分别具有发送功能的一个或多个设备和具有接收功能的一个或多个设备，或者可以包括具有发送功能和接收功能的一个或多个设备，此处不作限定。北斗地面发送/接收站22可用于北斗网络设备200在物理层(physical layer protocol，PHY)对数据的处理功能。北斗中心站23可用于北斗网络设备200在卫星链路控制层层和消息数据汇聚层(message data convergence protocol，MDCP)对数据的处理功能。北斗短报文融合通信平台24可用于在应用层(application layer protocol，APP)对数据的处理功能。
其中，上述北斗通信系统10中，发送设备可以向接收设备发送数据。当接收设备收到发送设备发送的数据帧后，可以向发送设备发送SLC层的确认字符(ACK)。发送设备可以基于ACK确定出接收设备是否成功接收数据帧。
接下来介绍本申请实施例中提供的一种北斗通信系统10的ACK机制。
图1B示出了本申请实施例提供的一种北斗通信系统中数据入站的传输过程。
如图1B所示，数据入站可以指终端100将数据发送给北斗网络设备200。例如，终端100可以向北斗地面收发站22发送数据帧。北斗地面收发站22可以将数据帧发送给北斗中心站23。北斗中心站23可以将数据帧汇聚成应用层报文上报给北斗短报文融合通信平台24。北斗中心站23可以在接收到终端100发送的数据帧后，向终端100返回SLC层的ACK。该ACK可用于指示北斗网络设备200是否成功收到终端100发送的数据帧。其中，数据帧可以指本申请实施例中的SLC PDU。
图1C示出了本申请实施例提供的一种北斗通信系统中数据出站的传输过程。
如图1C所示，数据出站可以指北斗网络设备200将数据发送给终端100。例如，北斗短报文融合通信平台24可以将应用层报文发送给北斗中心站23；然后，北斗中心站23可以将应用层报文拆分为一个或多个数据帧，并将该一个或多个数据帧通过北斗地面收发站22和北斗短报文卫星21发送至终端100。终端100可以在接收到北斗网络设备200发送的数据帧后，向北斗网络设备200返回SLC层的ACK。该ACK可用于指示终端100是否成功收到北斗网络设备200发送的数据帧。其中，数据帧可以指本申请实施例中的SLC PDU。
在一种可能的实现方式中，由于出站传输过程中，北斗网络设备200可以在SLC层将向多个终端发送的数据帧拼接在一起得到出站数据，再将出站数据发送给所有终端。因此，北斗网络设备200的SLC层出站资源紧张，处理重传数据会给北斗网络设备200带来运算资源的损耗。因此，北斗网络设备200可以在将数据发送出去后，将发送过的数据清除缓存。同理，终端100在接收到北斗网络设备200发送的数据帧后，不给北斗网络设备200返回SLC层的AKC。在出站传输过程中，没有SLC层的重传机制。
接下来介绍本申请实施例中提供的一种北斗通信系统10的入站数据的协议架构。
图2A示出了本申请实施例中提供的一种北斗通信系统10的入站数据的协议封装架构示意图。
如图2A所示，终端100上的北斗报文传输协议层可以分为应用层、消息数据汇聚层、卫星链路控制层和物理层。
终端100发送数据给北斗网络设备200时，终端100上的北斗报文传输协议的工作流程可以如下：
在APP层，终端100可以将原始数据进行编码压缩，得到压缩数据。终端100可以将压 缩数据进行加密，得到加密后数据。并在加密后数据前添加报文头信息，得到应用层报文。其中，原始数据可以包括但不限于用户输入的文本信息、接收用户的数量指示、接收用户的ID、终端100的位置信息、语音、图像、动画等。其中，报文头信息可以包括但不限于压缩指示字段、加密指示字段等等。其中，压缩指示字段可用于指示终端100压缩数据使用的编码压缩算法类型。加密指示字段用于指示终端100加密数据使用的加密算法类型。
可选的，终端100可以在编码压缩原始数据，得到压缩数据后，在压缩数据前添加上述压缩指示字段。终端100再使用密钥加密添加了压缩指示字段的压缩数据，得到加密后数据。
在MDCP层，终端100可以通过层间接口获取到APP层下发的应用层报文，并将应用层报文作为一个MDCP层的服务数据单元(server data unit，SDU)，简称为MDCP SDU。在MDCP层，终端100可以在MDCP SDU的尾部添加填充数据(padding)至指定长度，并给MDCP SDU添加冗余长度指示字段。该冗余长度指示字段可用于表示该填充数据的长度。终端100可以将填充数据以及增加冗余长度指示字段之后的MDCP SDU，拆分成一个或多个固定长度的MDCP分段数据(M_segment)，并在每个MDCP分段数据的头部添加后继指示字段，得到MDCP层的协议数据单元(protocol data unit，PDU)，简称为MDCP PDU。即MDCP PDU包括M_segment和后继指示字段。其中，后继指示字段可用于表示当前的MDCP PDU在同一个MDCP SDU中的多个MDCP PDU中的顺序，或者当前MDCP PDU为MDCP SDU的唯一一个MDCP PDU。
在SLC层，终端100可以通过层间接口获取到MDCP层下发的MDCP PDU，作为SLC层的SDU，即SLC SDU。在SLC层，终端100可以将SLC SDU分段成一个或多个(例如，4个)固定长度的SLC分段数据(S_segment)，并在每个S_segment头部添加帧头信息，得到SLC层的PDU，即SLC PDU。其中，帧头信息中包括服务数据单元交替指示(service data unit alternated Indicator，SAI)字段、帧总数字段和帧序号字段。
其中，SAI字段可用于表示该SLC PDU是否属于一个未发送过的SLC SDU。
帧总数字段，可用于表示该SLC PDU所属的SLC SDU中包括SLC PDU的总数量。
帧序号字段，可用于表示该SLC PDU在所属的SLC SDU中的序号。
在PHY层，终端100可以通过层间接口获取到SLC层下发的SLC PDU，并将SLC PDU作为用PHY层的用户帧。终端100可以对用户帧进行物理层处理(例如，编码、插导频、调制、扩频等操作)，得到入站数据。然后，终端100可以将入站数据发送给北斗短报文卫星21，经由北斗短报文卫星21中继转发给北斗网络设备200。
图2B示出了本申请实施例中提供的一种北斗通信系统10的入站数据的协议解析架构示意图。
如图2B所示，北斗网络设备200上的北斗报文传输协议层可以分为应用层、消息数据汇聚层、卫星链路控制层和物理层。其中，北斗网络设备200可以包括但不限于北斗地面收发站22、北斗中心站23和北斗短报文融合通信平台24。北斗地面收发站22可用于负责PHY层的协议处理。北斗中心站23可用于负责SLC层和MDCP层的协议处理。北斗短报文融合通信平台24可用于负责APP层的协议处理。
终端100发送数据给北斗网络设备200时，终端100上的北斗报文传输协议的工作流程可以如下：
在PHY层，北斗网络设备200可以获取终端100发送的入站数据。北斗网络设备200针对入站数据进行物理层处理(例如，解扩、解调、去导频、解码等操作)，得到用户帧，北斗 网络设备200可以通过层间接口将用户帧呈递给SLC层，作为SLC层的SLC PDU。
在SLC层，北斗网络设备200可以基于SLC PDU的帧头信息，将属于同一个SLC SDU的SLC PDU拼接成一个SLC SDU。北斗网络设备200可以将SLC SDU通过层间接口呈递给MDCP层，作为MDCP层的MDCP PDU。
在MDCP层，北斗网络设备200可以将属于同一个MDCP SDU的所有MDCP PDU按照接收时间拼接在一起，并将拼接后的MDCP PDU的填充数据和冗余长度指示字段去除得到MDCP SDU。北斗网络设备200可以将MDCP SDU通过层间接口呈递到APP层，作为APP层接收到的应用层报文。
在APP层，北斗网络设备200可以基于应用层报文的报文头，对应用层报文中的加密后数据进行解密，得到压缩数据。北斗网络设备200可以对压缩数据进行解压缩解码，得到原始数据。
本申请实施例中，上述协议处理过程仅为示例说明，本申请对协议处理的具体操作不作限定。
接下来介绍本申请实施例中提供的一种北斗通信系统10的出站数据的协议架构。
图3A示出了本申请实施例中提供的一种北斗通信系统10的出站数据的协议封装架构示意图。
如图3A所示，北斗网络设备200上的北斗报文传输协议层可以分为应用层、消息数据汇聚层、卫星链路控制层和物理层。
北斗网络设备200发送数据给终端100时，北斗网络设备200上的北斗报文传输协议的工作流程可以如下：
在APP层，北斗网络设备200可以将原始数据进行编码压缩，得到压缩数据。北斗网络设备200可以将压缩数据进行加密，得到加密后数据。并在加密后数据前添加报文头信息，得到应用层报文。其中，原始数据可以包括但不限于第三方服务器(例如，短消息中心25)发送的数据、文本、旗语、语音、图像、动画等。其中，报文头信息可以包括但不限于压缩指示字段、加密指示字段等等。其中，压缩指示字段可用于指示北斗网络设备200压缩数据使用的编码压缩算法类型。加密指示字段用于指示北斗网络设备200加密数据使用的加密算法类型。
可选的，北斗网络设备200可以在编码压缩原始数据，得到压缩数据后，在压缩数据前添加上述压缩指示字段。北斗网络设备200再使用密钥加密添加了压缩指示字段的压缩数据，得到加密后数据。
在MDCP层，北斗网络设备200可以通过层间接口获取到APP层下发的应用层报文，并将应用层报文作为一个MDCP SDU。北斗网络设备200可以将MDCP SDU拆分成一个或多个固定长度的MDCP分段数据(M_segment)，并在每个MDCP分段数据的头部添加后继指示字段，得到MDCP PDU，即MDCP PDU包括M_segment和后继指示字段。其中，后继指示字段可用于表示当前的MDCP PDU在同一个MDCP SDU中的顺序。
在SLC层，北斗网络设备200可以通过层间接口获取到MDCP层下发的MDCP PDU，作为SLC SDU。北斗网络设备200可以将SLC SDU分段成一个或多个(例如，4个)固定长度的SLC分段数据(S_segment)，并在每个S_segment头部添加帧头信息，得到SLC PDU。其中，北斗网络设备200的SLC层的描述可以参见上述图2A所述实施例，在此不再赘述。
在PHY层，北斗网络设备200可以通过层间接口获取到SLC层下发的SLC PDU，作为 用户帧。北斗网络设备200可以将多个用户或者一个用户的用户帧(又称为数据帧)拼接在一起，再加上帧头(例如版本号)和校验位得到物理帧。北斗网络设备200可以将物理帧进行物理层处理(例如，编码、插导频、调制、扩频等操作)后得到电文支路(S2C-d支路)的编码数据。北斗网络设备200可以将S2C-d支路的编码数据和导频支路(S2C-p支路)的导频数据(又称为副码)组成导频编码数据，即出站数据。并将出站数据发送给北斗短报文卫星21，经由北斗短报文卫星21中继转发给一个或多个终端。可以理解的是，S2C-p支路的导频数据与卫星波束相关。当卫星波束为已知信息时，S2C-p支路的导频数据也是已知的，无需解码。而S2C-d支路的编码数据是需要解码的。
图3B示出了本申请实施例中提供的一种北斗通信系统10的出站数据的协议解析架构示意图。
如图3B所示，终端100上的北斗报文传输协议层可以分为应用层、消息数据汇聚层、卫星链路控制层和物理层。
在PHY层，终端100可以基于北斗网络设备200发送的S2C-p支路的副码，捕获到将S2C-d支路的编码数据。终端100在捕获到S2C-d支路的编码数据后，可以对S2C-d支路的编码数据进行物理层处理(例如，解扩、解调、去导频、解码等操作)，得到物理帧。终端100可以从物理帧中提取出属于终端100的用户帧。终端100可以将用户帧通过层间接口呈递给SLC层，作为SLC层的SLC PDU。
在SLC层，当终端100收到的用户帧为通用数据帧时，终端100可以将属于同一个SLC SDU的SLC PDU拼接成一个SLC SDU。终端100可以将SLC SDU通过层间接口呈递给MDCP层，作为MDCP层的MDCP PDU。当终端100收到的用户帧为ACK帧时，终端100可以重传当前SLC SDU/发送下一个SLC SDU/停止发送SLC SDU。
在MDCP层，终端100可以将一个或多个MDCP PDU拼接成一个MDCP SDU。终端100可以将MDCP SDU通过层间接口呈递到APP层，作为APP层接收到的应用层报文。
在APP层，终端100可以对应用层报文进行解密得到压缩数据。终端100再对压缩数据进行解压缩解码，得到原始数据。
本申请实施例中，上述协议处理过程仅为示例说明，本申请对协议处理的具体操作不作限定。
下面介绍本申请实施例提供的ACK处理流程。
图4示出了本申请实施例中提供的北斗通信系统10中ACK处理流程示意图。
如图4所示，发送设备可以在应用层生成应用层报文。然后，发送设备可以将应用层报文下发至MDCP层，作为MDCP层的MDCP SDU。接着，发送设备可以在MDCP层将MDCP SDU分包为多个MDCP PDU。然后，发送设备可以将MDCP PDU下发至SLC层，作为SLC层的SLC SDU，并在SLC层将SLC SDU分帧为N个SLC PDU，其中N为正整数(例如4)。其中，SLC PDU的帧头信息中包括服务数据单元交替指示(service data unit alternated Indicator，SAI)字段、帧总数字段和帧序号字段。SAI字段可用于表示该SLC PDU是否属于一个未发送过的SLC SDU。帧总数字段可用于表示该SLC PDU所属的SLC SDU中包括SLC PDU的总数量。帧序号字段，可用于表示该SLC PDU在所属的SLC SDU中的序号。
发送设备可以将SLC SDU的SLC PDU发送至接收设备。接收设备可以基于SLC PDU的帧头信息判断是否收到SLC SDU的所有SLC PDU。
若接收设备基于帧头信息判定出已经接收到SLC SDU的所有SLC PDU，接收设备可以向发送设备发送第一ACK。其中，第一ACK可以用于指示接收设备已经接收到SLC SDU的所有SLC PDU。发送设备在收到第一ACK后，可以在SLC层确定出接收设备收到SLC SDU的SLC PDU。若发送设备发送的MDCP SDU的最后一个SLC SDU的SLC PDU，发送设备可以结束发送操作。若发送设备发送的MDCP SDU的非最后一个SLC SDU的SLC PDU，发送设备可以继续发送MDCP SDU的下一个SLC SDU的SLC PDU。
若接收设备基于帧头信息判定出未接收到SLC SDU的所有SLC PDU，接收设备可以向发送设备发送第二ACK。其中，第二ACK可以用于指示接收设备未接收到SLC SDU的所有SLC PDU。发送设备可以在接收到第二ACK后，向接收设备重传该SLC SDU的所有SLC PDU。
在一种可能的实现方式中，第二ACK还可以指示未接收到的SLC PDU的帧序号。发送设备在收到第二ACK后，可以向接收设备重传第二ACK指示的未接收到的SLC PDU。
示例性的，如图4所示，发送设备接收到第二ACK后，重传接收设备未收到的SLC PDU，接收设备收到SLC PDU后，可以向发送设备反馈第一ACK。
其中，在入站过程中，发送设备可以为终端100，接收设备可以为北斗网络设备200。在出站过程中，发送设备可以为北斗网络设备200，接收设备可以为终端100。
这样，可以在发送设备向接收设备发送的数据有丢失时，也可以保证数据的传输过程正常进行，接收设备可以接收到发送设备发送的数据。
在一种可能的实现方式中，由于在北斗通信系统中，很多业务都为突发式业务。终端100不需要时刻和北斗网络设备200保持联通，终端100只需要在通信时向北斗网络设备200发送一条业务请求，北斗网络设备200基于业务请求向终端100发送业务响应。如果北斗网络设备200设置有SLC层的重传机制，运算负担重，且有益效果不明显。当发送设备为北斗网络设备200，接收设备为终端100时，发送设备在收到第二ACK后，不给接收设备重传SLC SDU的SLC PDU。可选的，发送设备还可以停止向北斗网络设备200发送SLC SDU。这样，北斗网络设备200不在SLC层重传数据可以更好地节约有限的传输资源。
进一步可选的，当发送设备为北斗网络设备200，接收设备为终端100时，为了进一步节约北斗网络设备200的空口资源，终端100可以不给北斗网络设备发送SLC层的反馈ACK(包括第一ACK和第二ACK)。
图5示出了本申请实施例中提供的北斗通信系统10的MDCP层和SLC层对数据的协议处理流程示意图。其中，在入站过程中，发送设备为终端100，接收设备为北斗网络设备200。在出站过程中，发送设备为北斗网络设备200，接收设备为终端100。
1、发送设备在MDCP层对发送数据的协议封装过程。
如图5所示，在MDCP层，发送设备可以将MDCP SDU，拆分成一个或多个固定长度的MDCP分段数据(M_segment)，并在每个MDCP分段数据的头部添加后继指示字段，得到MDCP PDU，即MDCP PDU包括M_segment和后继指示字段。
需要说明的是，在入站过程中，首先，发送设备可以给MDCP SDU添加填充(padding)数据，和冗余长度指示字段。然后，发送设备可以将添加了填充数据和冗余长度指示字段的MDCP SDU拆分成一个或多个固定长度的MDCP分段数据，并在每个MDCP分段数据的头部添加后继指示字段，得到MDCP PDU。
需要说明的是，在出站过程中，发送设备可以直接将MDCP SDU拆分成一个或多个固定长度的MDCP分段数据，并在每个MDCP分段数据的头部添加后继指示字段，得到MDCP  PDU。
发送设备可以将拆分得到的MDCP PDU，按照高比特位到低比特位的先后顺序存入MDCP层发送缓冲区(MDCP Tx buffer)中：
其中，后继指示字段的数据长度可以占用2比特(bit)。后继指示字段的值含义可以如下：
01：表示该MDCP PDU为本个MDCP SDU中多个MDCP PDU中的起始MDCP PDU；
10：表示该MDCP PDU为本个MDCP SDU中多个MDCP PDU中的中间MDCP PDU，即，指本个MDCP SDU中除了起始MDCP PDU和最后一个MDCP PDU之外的其他MDCP PDU；
11：表示该MDCP PDU为本个MDCP SDU中多个MDCP PDU中的最后一个MDCP PDU；
00：表示该MDCP PDU为本个MDCP SDU中唯一一个MDCP PDU。
示例性的，如图5所示，终端100可以将MDCP SDU拆分成3个MDCP PDU，其中，按照高比特位到低比特位的顺序，这3个MDCP PDU依次是MDCP PDU0、MDCP PDU1和MDCP PDU2。其中，由于MDCP PDU0是当前MDCP SDU中的起始MDCP PDU，终端100可以将MDCP PDU0中后继指示字段的值设置为“01”。由于MDCP PDU1是当前MDCP SDU中的中间MDCP PDU，终端100可以将MDCP PDU1中后继指示字段的值设置为“10”。MDCP PDU2是当前MDCP SDU中的最后一个MDCP PDU，终端100可以将MDCP PDU2中后继指示字段的值设置为“11”。
2、发送设备在SLC层对发送数据的协议封装过程。
在SLC层，发送设备在SLC层可以通过SLC层发送状态控制器，控制SLC层的SLC PDU发送策略，包括SLC PDU的初传和重传。发送设备还可以基于接收设备发送的接收反馈(例如，ACK)，控制SLC PDU的发送和重传。发送设备可以通过层间接口获取到MDCP层下发的MDCP PDU，作为SLC SDU。其中，当发送设备向接收设备发送前一个SLC SDU，并确认接收设备接收成功之后，才会从MDCP层获取到下一个MDCP PDU作为下一个SLC SDU，发送给接收设备。
示例性，发送设备可以将MDCP PDU0、MDCP PDU1和MDCP PDU2中的MDCP PDU0下发至SLC层。在SLC层，发送设备首先通过层间接口获取到MDCP层下发的MDCP PDU0，发送设备可以将MDCP PDU0作为本次报文传输过程中SLC层的首个SLC SDU(即，SLC SDU0)发送给接收设备。在发送设备确定已经将接收设备将SLC SDU0的数据发送给接收设备后，发送设备可以从MDCP层获取MDCP PDU1，并将MDCP PDU1作为本次报文传输过程第2个SLC SDU(即，SLC SDU1)发送给接收设备。在发送设备确定已经将接收设备将第2个SLC SDU的数据发送给接收设备后，发送设备可以从MDCP层获取MDCP PDU2，并将MDCP PDU2作为本次报文传输过程最后一个SLC SDU发送给接收设备。
可选的，发送设备可以通过层间接口将MDCP层的MDCP SDU的所有MDCP PDU下发至SLC层，作为SLC层的SLC SDU。其中，当发送设备向接收设备发送前一个SLC SDU，并确认接收设备接收成功之后，再发送下一个SLC SDU给接收设备。
示例性的，发送设备可以将MDCP PDU0、MDCP PDU1和MDCP PDU2都下发至SLC层。在SLC层，发送设备首先通过层间接口获取到MDCP层下发的MDCP PDU0、MDCP PDU1和MDCP PDU2，发送设备可以将MDCP PDU0作为本次报文传输过程中SLC层的首个SLC SDU(即，SLC SDU0)。将MDCP PDU1作为本次报文传输过程中SLC层的第2个SLC SDU(即，SLC SDU1)。将MDCP PDU2作为本次报文传输过程中SLC层的第3个SLC SDU(即，SLC SDU2)。在发送设备确定已经将接收设备将SLC SDU0的数据发送给接收设备后，发送 设备可以将SLC SDU1发送给接收设备，以此类推。
上述示例仅仅用于解释本申请，不应构成限定。
在SLC层，发送设备可以将SLC SDU分段成一个或多个固定长度的SLC分段数据(S_segment)，并在每个S_segment头部添加帧头信息，得到SLC PDU。其中，帧头信息中包括SAI字段、帧总数字段和帧序号字段。其中：
SAI字段可以占用1bit。SAI字段的值可以为“0”或“1”。发送设备可以判断当前要发送的SLC PDU是否属于一个未发送过的SLC SDU，若是，则发送设备可以设置SLC PDU中的SAI字段的值与前一个SLC SDU会话(包括SLC SDU初传会话或SLC SDU重传会话)中SLC PDU的SAI字段的值不同；若否，则发送设备可以设置SLC PDU中SAI字段的值与前一个SLC SDU会话中SLC PDU的SAI字段的值相同。当SLC PDU中SAI字段的值与前一个SLC SDU会话中SLC PDU的SAI字段的值相同时，表示该SLC PDU是重传数据。
示例性的，发送设备在整个应用层报文传输过程中，需要传输3个SLC SDU。每个SLC SDU可以包括4个SLC PDU。其中，第1个SLC SDU(即，SLC SDU0)中4个SLC PDU的SAI字段的值可以都为“0”，第2个SLC SDU(即，SLC SDU1)中4个SLC PDU的SAI字段的值可以都为“1”。第3个SLC SDU中4个SLC PDU的SAI字段的值可以都为“0”。
上述示例仅仅用于解释本申请，不应构成限定。
3、接收设备在SLC层对接收数据的协议解析过程。
在SLC层，接收设备接收发送设备的SLC PDU后，可以基于SLC PDU的帧头信息判断是否接收完一个SLC SDU中的所有SLC PDU。
若判定出已接收完一个SLC SDU中的所有SLC PDU，则接收设备可以将这接收到的一个或多个SLC PDU按照帧序号字段的值由小到大，顺序拼接成一个SLC SDU。进一步的，接收设备还可以向发送设备发送反馈信息(例如，第一ACK)，发送设备收到反馈信息后可以基于反馈信息确认接收设备接收到所有的SLC PDU。
若判定出未接收完一个SLC SDU中的所有SLC PDU，则接收设备在SLC层接收窗结束后，可以发送反馈信息(例如，第二ACK)通知发送设备重传未接收到的SLC PDU。接收设备可以在拼接完SLC SDU后，通过层间接口将SLC SDU上报给MDCP层，作为MDCP PDU。
其中，接收设备在SLC层可以通过SLC层接收状态控制器，基于SLC PDU中的SAI字段，控制SLC层的反馈信息(例如，ACK)的发送策略以及SLC PDU的拼接。该SLC层接收状态控制器的持续时间为发送设备上SLC PDU的最大重传时间。
示例性的，若接收设备接收到的第1个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“00”。第2个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“01”。第3个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“10”。第4个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“11”。接收设备判定出已接收完第一个SLC SDU(即SLC SDU0)中的所有SLC PDU，接收设备可以将这4个SLC PDU按照帧序号从小到大顺序，拼接成SLC SDU0，并上报给MDCP层，作为MDCP层的MDCP PDU0。接收设备可以将MDCP PDU0存入MDCP层接收缓冲区(MDCP Rx buffer)中。其中，MDCP PDU0中后继指示字段的值为“01”。
进一步的，接收设备的SLC层接收状态控制器可以向发送设备的SLC层发送状态控制器发送ACK。
在一种可能的实现方式中，ACK帧可以包括帧头信息和位图(bitmap)字段。其中，位图字段可以用于反馈接收设备的SLC PDU的接收情况。例如，bitmap字段的长度可以为1bit， bitmap的值可以指示是否接收到SLC SDU的所有SLC PDU。例如，当bitmap字段的值为0时，可以表明未接收到SLC SDU的所有SLC PDU，当bitmap字段的值为1时，可以表明接收到SLC SDU的所有SLC PDU，在此，上述示例仅仅用于解释本申请，不应构成限定。
再例如，bitmap字段的长度可以为4bit，bitmap的每一个比特位都可以标记是否接收到对应的帧序号的SLC PDU。其中，bitmap的首位可以用于标记第一个SLC PDU(例如帧序号为00)的接收情况，第二位可以用于标记第二个的SLC PDU(例如帧序号为01)的接收情况，以此类推。当bitmap的某个比特位的值为0时，表明接收设备在接收窗内未接收到该比特位对应的SLC PDU。当bitmap的某个比特位的值为1时，表明接收设备在接收窗内已经接收到该比特位对应的SLC PDU。
在此，由于接收设备接收到SLC SDU0的所有SLC PDU。所以bitmap的值为1111。当发送设备接收到接收设备发送的第一ACK后，基于第一ACK的bitmap的值，确认接收设备已经成功接收SLC PDU0的所有SLC PDU，开始发送SLC SDU1。
又示例性的，若接收设备接收到的第1个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“00”。第2个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“10”。第3个SLC PDU的SAI值为“0”、帧总数值为“11”、帧序号为“11”。接收设备在接收窗时间内，未接收到SLC SDU0的SAI值为“0”、帧总数值为“11”、帧序号为“01”的SLC PDU，也就是未接收到SLC SDU0的所有SLC PDU中的第二个SLC PDU(帧序号为01)。接收设备的SLC层接收状态控制器可以向发送设备的SLC层发送状态控制器发送第二ACK。其中，第二ACK的bitmap字段的值为1011。当发送设备接收到接收设备发送的第二ACK后，基于bitmap的值，确认接收设备未接收到SLC PDU0的第二个SLC PDU，发送设备重传SLC PDU0的第二个SLC PDU。
4、接收设备在MDCP层对接收数据的协议解析过程。
在MDCP层，接收设备可以在接收到发送设备发送的一个MDCP SDU的所有MDCP PDU后，基于MDCP PDU中的后继指示字段，按接收的时间顺序聚合多个MDCP PDU，得到MDCP SDU。
例如，当接收设备从SLC层获取到后继指示字段的值为“11”的MDCP PDU后，接收设备可以从MDCP Rx buffer中将所有MDCP PDU取出，并按照后继指示字段的值以及接收时间顺序进行拼接，得到MDCP SDU。接收设备可以将MDCP SDU通过层间接口上报给应用层，作为应用层报文。
需要说明的是，在入站过程中，接收设备在按照后继指示字段的值以及接收时间顺序进行拼接后，还要去除冗余指示字段和padding数据，得到MDCP SDU。
这样，发送设备和接收设备之间可以通过ACK确保SLC层的数据不会有丢失。
但是，如果只采用SLC层的确认机制，发送设备基于ACK确定出接收设备的SLC层是否成功接收到发送设备发送的应用层报文的所有SLC PDU，但并不代表接收设备的应用层可以成功解析收到的应用层报文。这样，不能可靠地指示接收设备是否能得到发送设备发送的原始数据(即接收设备无法解析出应用层报文的原始数据)。
也就是说，如果发送设备向接收设备发送数据时，在SLC层发送成功，但应用层解密或者解码失败，接收设备无法解析得到应用层报文的原始数据，发送设备也无法确认接收设备的解析情况。这就会造成发送设备的用户认为自己已经将北斗短消息发送至接收设备，而接收设备却无法获取接收成功的原始数据的情况。而且，即使接收设备无法获取原始数据，但运营商根据SLC层确认应用层报文发送/接收成功，收取了用户的通信费用，收费不合理，造 成用户体验不佳。
甚至，在一些紧急情况下，只进行SLC层确认还可能造成严重后果，例如，终端100向北斗网络设备200发送紧急救援信息时，只在SLC层进行确认，如果发生应用层解密/解码失败的情形，终端100的用户并不知情，不会再发送第二条紧急救援信息。北斗网络设备200无法解码/解密收到的应用层报文，无法将应用层报文中的救援信息发送至紧急救援中心27，延误救援时间。
因此，本申请提供了一种北斗通信系统中应用层回执传输方法。接收设备可以在接收到发送设备发送的应用层报文后，解析应用层报文，基于解析应用层报文的结果得到对应的应用层回执信息。接收设备可以将应用层回执信息发送至发送设备，发送设备可以基于应用层回执信息确认接收设备解析应用层报文的情况(例如解析成功，解析失败)。采用本申请实施例提供的方法，可以建立可信的报文传输机制，保证发送设备可以得到接收设备解析应用层报文的情况。
进一步的，发送设备还可以基于应用层回执信息执行相应的操作。例如，如果应用层回执信息指示接收设备解析应用层报文成功，发送设备结束此次发送操作。如果应用层回执信息指示接收设备解析应用层报文失败，发送设备可以重传应用层报文。这样，可以进一步保证北斗通信系统的传输可靠性。
下面具体介绍北斗通信系统中应用层回执传输方法的传输过程。
如图6A所示，在入站过程中，终端100将数据发送给北斗网络设备200。具体的，终端100可以向北斗地面收发站22发送入站数据。北斗地面收发站22可以将入站数据进行物理层处理(例如，解扩、解调、去导频、解码等操作)，得到用户帧，并将用户帧发送给北斗中心站23。北斗中心站23可以将用户帧作为SLC PDU并将SLC PDU汇聚成应用层报文上报给北斗短报文融合通信平台24。北斗中心站23可以在接收到终端100发送的SLC PDU后，向终端100返回SLC层的确认字符(ACK)。该ACK可用于指示北斗网络设备200是否成功收到终端100发送的SLC PDU。北斗短报文融合通信平台24可以解析收到的应用层报文，得到应用层解析信息。该应用层解析信息可用于指示北斗网络设备200是否成功解析终端100发送的应用层报文。
如图6B所示，在出站过程中，北斗网络设备200将数据发送给终端100。具体的，北斗短报文融合通信平台24将应用层报文发送至北斗中心站23，北斗中心站23可以将应用层报文拆分为多个用户帧并将该多个用户帧依次发送至北斗地面收发站22。北斗地面收发站22可以将用户帧拼接放入物理帧，并将物理帧进行物理层处理(例如，编码、插导频、调制、扩频等操作)得到出站数据并将出站数据发送至终端100。终端100可以在接收到北斗网络设备200发送的出站数据后，对出站数据进行物理层处理(例如，解扩、解调、去导频、解码等操作)，得到物理帧。终端100可以从物理帧中取出终端100的用户帧，并将其上传至SLC层作为SLC PDU。终端100在收到SLC PDU后，可以向北斗网络设备200返回SLC层的ACK。该ACK可用于指示终端100接收北斗网络设备200发送的SLC PDU的情况。终端100还可以将收到的SLC PDU汇聚成应用层报文，并解析得到的应用层报文。终端100可以基于解析应用层报文的结果生成对应的应用层回执信息。该应用层回执信息可用于指示终端100是否成功解析北斗网络设备200发送的应用层报文。
下面具体介绍北斗通信系统10中一种可能的应用层的回执处理机制。
图7示出了本申请实施例中发送设备和接收设备间的一种可能的应用层回执处理机制。
如图7所示，接收设备可以在接收到发送设备发送的应用层报文对应的所有SLC PDU后，向发送设备发送ACK和应用层回执信息。具体的，应用层的回执处理流程如下：
S701，发送设备生成应用层报文。
在APP层，发送设备可以将原始数据进行编码压缩得到压缩数据，再将压缩数据加密得到加密后数据，并给加密后数据添加报文头信息得到应用层报文。
S702，发送设备将应用层报文通过层间接口从APP层下发至MDCP层。
S703，发送设备将应用层报文作为MDCP SDU，基于MDCP SDU得到M个MDCP PDU。
在MDCP层，发送设备可以将应用层报文作为MDCP SDU，并将MDCP SDU拆分成M个MDCP PDU，其中M为正整数。需要说明的是，当发送设备为终端100时，发送设备需要给MDCP SDU添加填充数据和冗余长度指示字段。再将添加了填充数据和冗余长度指示字段的MDCP SDU拆分成M个MDCP PDU。
S704，发送设备将MDCP PDU通过层间接口从MDCP层下发至SLC层。
S705，发送设备将MDCP PDU作为SLC SDU，并将SLC SDU分帧为N个SLC PDU。
在SLC层，发送设备可以将MDCP PDU作为SLC SDU，并将SLC SDU分帧为SLC PDU。具体的描述可以参见上述图5所述实施例，在此不再赘述。
S706，发送设备将SLC PDU发送至接收设备。
具体的，发送设备可以将SLC PDU通过层间接口从SLC层下发至PHY层。
在PHY层，发送设备可以针对SLC层下发的SLC PDU执行物理层处理(例如，编码、插导频、调制、扩频等操作)后，将其转发至接收设备。在此，发送设备为终端100时，发送设备在PHY层执行的操作的详细描述可以参见上述图2A所述实施例，发送设备为北斗网络设备200时，发送设备在PHY层执行的操作的详细描述可以参见上述图3A所述实施例，在此不再赘述。
接收设备在PHY层接收到发送设备发送的数据后，对接收到的数据进行解调解码等操作。之后，接收设备可以将执行物理层处理(例如，解扩、解调、去导频、解码等操作)之后的数据上传至SLC层，作为SLC层的SLC PDU。其中，当接收设备为北斗网络设备200时，接收设备在PHY层执行操作的详细描述可以参见上述图2B所述实施例。当接收设备为终端100时，接收设备在PHY层执行操作的详细描述可以参见上述图3B所述实施例，在此不再赘述。
S707，发送设备向接收设备发送第一ACK。
在SLC层，接收设备可以基于SLC PDU的帧头信息向发送设备回复ACK。
若接收设备基于帧头信息判定出未接收到SLC SDU的所有SLC PDU，接收设备可以向发送设备发送第二ACK。其中，第二ACK可以用于指示接收设备未接收到SLC SDU的所有SLC PDU，且第二ACK还可以指示未接收到的SLC PDU的帧序号。发送设备在收到第二ACK后，可以向接收设备重传第二ACK指示的未接收到的SLC PDU。
若接收设备基于帧头信息判定出已经接收到SLC SDU的所有SLC PDU，接收设备可以向发送设备发送第一ACK。其中，第一ACK可以用于指示接收设备已经接收到SLC SDU的所有SLC PDU。发送设备在收到第一ACK后，确定出接收设备收到SLC SDU的SLC PDU。在此，下述实施例以接收设备接收到SLC SDU的所有SLC PDU这种情形来描述。
需要说明的是，若发送设备发送的MDCP SDU的非最后一个SLC SDU的SLC PDU，发 送设备可以在接收到第一ACK后，继续发送MDCP SDU的下一个SLC SDU的SLC PDU。
若发送设备发送的MDCP SDU的最后一个SLC SDU的SLC PDU，发送设备可以等待接收设备发送应用层回执信息。其中，由于接收设备只需要在接收到最后一个SLC SDU对应SLC SDU的所有SLC PDU后，就可以向发送设备发送指示接收到所有SLC PDU的第一ACK。接收设备需要拼接MDCP SDU对应的所有SLC PDU得到应用层报文后，才能开始解析应用层报文，并基于解析应用层报文的结果回复对应的应用层回执信息，所以发送设备接收到第一ACK的时间短于应用层回执信息。
S708，接收设备将SLC PDU拼接为SLC SDU。
具体的，接收设备拼接SLC PDU的详细描述可以参见图5所示实施例，在此不再赘述。
S709，接收设备将SLC SDU通过层间接口从SLC层上传至MDCP层。
S710，接收设备可以将SLC SDU作为MDCP PDU，并基于MDCP PDU得到MDCP SDU。
在MDCP层，接收设备可以基于后继指示字段判定出接收到MDCP SDU的所有MDCP PDU后，可以将MDCP PDU按照接收顺序拼接为MDCP SDU。
S711，接收设备将MDCP SDU通过层间接口从MDCP层上传至APP层。
S712，接收设备将MDCP SDU作为应用层报文，解析应用层报文并基于解析应用层报文的结果生成应用层回执信息。
在APP层，接收设备可以将MDCP SDU作为应用层报文，并解析该应用层报文。接收设备可以在解析应用层报文后，基于解析应用层报文的结果生成对应的应用层回执信息。
具体的，当接收设备解析应用层报文失败时，接收设备可以生成用于指示解析失败的应用层回执信息。当接收设备解析应用层报文失败时，接收设备可以生成用于指示解析成功的应用层回执信息。
示例性的，应用层回执信息可以为错误码。错误码的长度可以为1bit。当错误码的值为0时，可以指示接收设备解析应用层报文失败。当错误码的值为1时，可以指示接收设备解析应用层报文成功。需要说明的是，此处的错误码数值及其含义仅为示例。
S713，接收设备将应用层回执信息发送给发送设备。
接收设备可以将应用层回执信息封装为回执帧，并将回执帧发送到发送设备。其中，接收设备得到回执帧与发送设备得到应用层回执信息的详细描述可以参见图9、图10所示实施例。或者，接收设备可以将应用层回执信息封装为应用层回执报文，并将应用层回执报文发送给发送设备。其中，接收设备得到应用层回执报文与发送设备得到应用层回执信息的详细描述可以参见后续所述实施例，在此不再赘述。
发送设备可以在APP层基于接收到的应用层回执信息确定出接收设备解析应用层报文的结果。
进一步的，发送设备还可以基于应用层回执信息中接收设备解析应用层报文的结果，执行相应的操作。例如，如果应用层回执信息指示接收设备解析应用层报文成功，发送设备结束此次发送操作或者发送下一个应用层报文。如果应用层回执信息指示接收设备解析应用层报文失败，发送设备可以重传应用层报文。这样，可以进一步保证北斗通信系统的传输可靠性。
在一种可能的实现方式中，应用层回执信息不仅可以指示接收设备解析应用层报文是否成功。并且，当接收设备解析失败时，应用层回执信息还可以指示接收设备解析应用层报文失败的原因。这样，发送设备可以从应用层回执信息中获得接收设备是否成功解析应用层报 文的结果，以及解析失败时解析失败的原因。
具体的，接收设备可以在解析应用层报文后，确定出解析应用层报文的结果对应的编码(又称为错误码)。其中，错误码为接收设备的应用层回执信息。
示例性的，错误码的长度可以为4bit。当错误码的值为0000时，可以指示接收设备成功解析应用层报文。当错误码的值为0001时，可以指示接收设备解析应用层报文失败，且失败原因为解密错误。当错误码的值为0010时，可以指示接收设备解析应用层报文失败，且失败原因为解码错误。等等。
需要说明的是，接收设备不能基于加密后数据解密得到压缩数据时，接收设备可以确定出解析应用层报文的结果为解密错误。接收设备不能基于压缩数据解压缩、解码得到原始数据时，接收设备可以确定出解析应用层报文的结果为解码错误。接收设备成功解析应用层报文得到原始数据时，接收设备确定出解析应用层报文的结果为解析成功。
具体的，接收设备可以在应用层解析应用层报文，并在得到解析应用层报文的结果后，将结果对应的错误码经过层间接口下发至SLC层。接收设备可以在错误码的头部添加帧头信息，得到SLC层的回执帧(又称为应用层回执)。其中，回执帧包括应用层回执信息(即错误码)。接收设备可以将回执帧发送至发送设备。
发送设备在接收到回执帧后，可以基于回执帧中的错误码确定出接收设备解析应用层报文的情况。
进一步的，发送设备在接收到回执帧后，还可以基于回执帧中的错误码执行相应的操作。
若错误码指示接收设备成功解析应用层报文，发送设备可以结束此次发送操作。
若错误码指示接收设备解析应用层报文失败且失败原因为解密错误。发送设备可以确定出接收设备解密错误的原因是发送设备的密钥信息和接收设备的密钥信息不同，发送设备可以在收到回执帧后，和接收设备协商更新密钥信息(包括密钥、密码本)。
具体的，发送设备和接收设备可以在回到蜂窝网络后，通过蜂窝网络设备协商密钥。其中，若发送设备和接收设备协商密钥信息后，发送设备的密钥信息更改为接收设备的密钥信息。发送设备可以基于更改后的密钥信息重新加密压缩数据，得到加密后数据。发送设备再将包括加密后数据的应用层报文发送至接收设备。
或者，若发送设备和接收设备协商密钥信息后，接收设备的密钥信息更改为发送设备的密钥信息，接收设备可以基于更改后的密钥信息重新解密应用层报文的加密后数据。
若错误码指示接收设备解析应用层报文失败且失败原因为解码错误，发送设备可以确定出解码错误的原因是发送设备的编码压缩算法和接收设备的编码压缩算法不同，发送设备和接收设备可以协商编码压缩算法。
具体的，发送设备和接收设备可以在回到蜂窝网络后，通过蜂窝网络设备协商编码加密算法。其中，若发送设备和接收设备协商编码压缩算法后，发送设备的编码压缩算法更改为接收设备的编码压缩算法。发送设备可以基于更改后的编码压缩算法重新编码压缩原始数据，得到压缩数据。发送设备加密压缩数据得到加密后数据，再将包括加密后数据的应用层报文发送至接收设备。
或者，若发送设备和接收设备协商编码压缩算法后，接收设备的编码压缩算法更改为发送设备的编码压缩算法，接收设备可以基于更改后的编码压缩算法重新解码压缩数据。
在一些实施例中，发送设备和接收设备都存储有码本，码本中包括发送设备和接收设备使用的编码压缩算法，当发送设备和接收设备的码本相同时，接收设备可以成功解码压缩数据得到原始数据。当发送设备和接收设备的码本不相同时，接收设备不能解码压缩数据得到 原始数据。
在一种可能的实现方式中，发送设备可以在基于应用层回执信息确定出接收设备解析应用层报文成功时，显示提示信息1。提示信息1可以用于提示消息发送成功。发送设备可以在基于应用层回执信息确定出接收设备解析应用层报文失败时，显示提示信息2。提示信息2可以用于提示消息发送失败。
可选的，发送设备可以在基于应用层回执信息确定出接收设备解析应用层报文失败且失败原因为解密失败时，显示提示信息3。提示信息3可以用于提示因为密钥错误导致消息发送失败。进一步的，提示信息3可以提示发送设备的用户回到蜂窝网络更新密钥后，再发送北斗短消息。
发送设备可以在基于应用层回执信息确定出接收设备解析应用层报文失败且失败原因为解码失败时，显示提示信息4。提示信息4可以用于提示因为编码加密算法错误导致消息发送失败。进一步的，提示信息3可以提示发送设备的用户回到蜂窝网络更新编码加密方式后，再发送北斗短消息。
在一种可能的实现方式中，接收设备可以预设为在接收到发送设备的应用层报文对应的最后一个SLC SDU的所有SLC PDU后，只回复SLC层的ACK。或者，接收设备可以预设为既回复SLC层的ACK，又回复应用层回执信息。或者，接收设备可以预设为只回复应用层回执信息。
在一种可能的实现方式中，发送设备可以在应用层报文的报文头中添加回执指示字段。发送设备可以通过回执指示字段指示接收设备是否回复应用层回执信息。这样，北斗通信系统可以在需要确认接收设备解析应用层报文的结果的情况下，保证传输的可靠性。在不需要确认接收设备解析应用层报文的结果的情况下，节约传输空口资源。
示例性的，在APP层，发送设备可以将原始数据进行编码压缩、加密等操作得到加密后数据。并给加密后数据添加报文头信息得到应用层报文。其中，应用层报文的具体格式可以参照图8。
示例性的，图8示出了一种发送设备的应用层报文的示例。在图8所示的应用层报文示例中。应用层报文由报文头和加密后数据组成。其中，解密后数据可以为原始数据经过压缩加密得到。报文头信息可以包括但不限于回执指示字段，加密指示字段，压缩指示字段等等。其中，加密指示字段和压缩指示字段的详细描述可以参见上述图2A所述实施例，在此不再赘述。其中，回执指示字段可以用于指示是否需要接收设备回复应用层回执信息。
例如，回执指示字段的长度可以为1bit。当回执指示字段的值为0时，可以用于指示接收设备不回复应用层回执信息。当回执指示字段的值为1时，可以用于指示接收设备回复应用层回执信息。
在MDCP层，发送设备可以将得到的APP层下发的应用层报文，作为MDCP SDU。发送设备可以将MDCP SDU分包为一个或多个固定长度的MDCP分段数据。发送设备可以在每个MDCP分段数据的头部添加后继指示字段，得到MDCP PDU。其中，后继指示字段可用于表示当前的MDCP PDU在同一个MDCP SDU中的顺序。其中，需要说明的是，当发送设备为终端100时，发送设备可以给MDCP SDU添加填充数据和冗余长度指示字段。并将添加了填充数据和冗余长度指示字段的MDCP SDU分包为一个或多个固定长度的MDCP分段数据。
在SLC层，发送设备可以将MDCP PDU作为SLC SDU分帧为SLC PDU。
在PHY层，发送设备可以将SLC PDU进行物理层处理(例如，编码、插导频、调制、扩频等操作)得到物理帧，并将物理帧发送至接收设备。
在PHY层，接收设备可以在收到物理帧后，针对物理帧进行物理层处理(例如，解扩、解调、去导频、解码等操作)后将其上传至SLC层。
在SLC层，接收设备可以基于SLC PDU的接收情况向发送设备反馈ACK。接收设备收到SLC SDU对应的所有SLC PDU后，可以将SLC PDU组帧得到SLC SDU。其中，接收设备反馈ACK具体流程可以参见上述实施例，在此不再赘述。
接收设备可以将SLC SDU上传至MDCP层，作为MDCP PDU。接收设备可以在基于后继指示字段判定出接收到MDCP SDU的所有MDCP PDU后，可以将MDCP PDU按照接收顺序拼接为MDCP SDU，并将MDCP SDU上传至APP层。
在APP层，接收设备可以将MDCP SDU作为应用层报文，并解析该应用层报文。首先，接收设备可以基于回执指示字段判断是否回复应用层回执信息。若接收设备基于回执指示字段判定出不回复应用层回执信息，接收设备直接解析应用层报文。
若接收设备基于回执指示字段判定出回复应用层回执信息，接收设备可以在解析应用层报文后，基于解析应用层报文的结果生成对应的应用层回执信息。接收设备在生成应用层回执信息后，可以将应用层回执信息发送给发送设备。
在一些可能的实施例中，接收设备可以在MDCP层解析回执指示字段。并基于回执指示字段的值判断是否回复应用层回执信息。需要说明的是，在以下实施例的描述中，应用层回执信息可以在SLC层封装为回执帧。也就是说，回执指示字段可以指示接收设备是否回复应用层回执信息可以表述为回执指示字段可以指示接收设备是否回复回执帧。
示例性的，接收设备可以在基于后继指示字段判定出接收到MDCP SDU的所有MDCP PDU后，可以将MDCP PDU按照接收顺序拼接为MDCP SDU。之后，接收设备可以基于回执指示字段判断是否回复回执帧。
当接收设备判定出不回复回执帧(例如回执指示字段的值为0)时，接收设备将MDCP SDU上传至APP层。在APP层，接收设备可以将MDCP SDU作为应用层报文并解析该应用层报文。
当接收设备判定出回复回执帧(例如回执指示字段的值为1)时，接收设备可以直接将MDCP SDU上传至APP层，将MDCP SDU作为应用层报文并解析该应用层报文。其中，接收设备还可以通知APP层生成应用层回执信息。接收设备可以在解析应用层报文后，基于解析应用层报文的结果生成对应的应用层回执信息。接收设备可以将应用层回执信息封装为回执帧并将回执帧发送至发送设备。发送设备可以基于应用层回执信息确定出接收设备解析应用层报文的结果。进一步的，发送设备可以基于应用层回执信息执行相应的操作，具体的，可以参见上述图7所述实施例，在此不再赘述。
其中，当接收设备为北斗网络设备200时，回执帧的具体描述可以参见图9所述实施例。
接下来介绍本申请实施例提供的一种北斗网络设备200发送回执帧的示例。
如图9所示，首先，北斗网络设备200可以在SLC层生成回执帧。具体的，北斗网络设备200可以将解析应用层报文的结果对应的应用层回执信息下发至SLC层。其中，应用层回执信息可以为通知消息，北斗网络设备200可以在SLC层根据通知消息生成解析应用层报文 结果对应的回执帧。
或者，应用层回执信息可以为错误码。在SLC层，北斗网络设备200可以将应用层回执帧信息写入用户信息。
其中，例如，错误码的长度可以为4bit，每一个错误码对应一种解析应用层报文的结果。例如，错误码的部分值的含义可以如下：
0000：指示北斗网络设备200解析应用层报文成功。
0001：指示北斗网络设备200由于解密错误导致解析应用层报文失败。
0010：指示北斗网络设备200由于解码错误导致解析应用层报文失败。
之后，北斗网络设备200可以在用户信息前添加帧头信息，得到回执帧。其中，帧头信息可以包括但不限于起始标识字段、帧长字段、用户身份证明(identity，ID)字段和帧类型字段。
其中，起始标识字段可以用于标识北斗网络设备200的一个新的用户帧的起始位置。
帧长字段可以用于标识用户帧的长度。
用户ID字段可以用于标识接收应用层回执的设备(例如，终端100)。终端100可以根据用户ID字段的值从出站数据中取出属于终端100的用户帧。
帧类型字段可以用于标识用户帧的类型。例如，帧类型字段的长度可以为2bit。当帧类型字段的值为00时，可以标识当前用户帧为通用数据帧。其中，通用数据帧可以用于传输原始数据。当帧类型字段的值为01时，可以标识当前用户帧为ACK帧。其中，ACK帧可以用于确认SLC层的SLC PDU的传输情况。当帧类型字段的值为10时，可以标识当前用户帧为回执帧。其中，回执帧可以用于确认应用层的应用层报文解析情况。在此，北斗网络设备200向终端100发送的用户帧为回执帧，故而帧类型字段的值可以为10。
之后，北斗网络设备200可以将回执帧和其他用户帧拼接在一起，并在多个用户帧的头部添加版本号字段。其中，版本号字段可以用于指示北斗短报文协议的版本。北斗网络设备100还可以在多个用户帧的尾部添加校验码(例如，循环冗余校验(cyclic redundancy check，CRC)码)，得到物理帧。其中，北斗网络设备200可以对物理帧执行物理层处理(例如，编码、插导频、调制、扩频等操作)并给物理帧加上保留段组成一个固定长度的物理时隙的S2C-d支路的编码数据。然后，北斗网络设备200可以将S2C-d支路的编码数据和S2C-p支路的副码同步发送给北斗短报文卫星21，经由北斗短报文卫星21中继转发给一个或多个终端(包括终端100)。
本申请实施例中，上述回执帧处理机制仅为示例说明，本申请对回执帧处理机制的具体操作不作限定。
之后，终端100可以基于北斗网络设备200发送的S2C-p支路的副码，捕获到将S2C-d支路的编码数据。终端100在捕获到S2C-d支路的编码数据后，可以对S2C-d支路的编码数据进行物理层处理(例如，解扩、解调、去导频、解码等操作)，得到物理帧。并从物理帧中取出用户ID字段的值和终端100的用户ID的值相同的用户帧。
当终端100基于帧头信息中的帧类型字段得到用户帧的类型为回执帧时，终端100可以在SLC层将回执帧中的错误码通过层间接口上传至APP层，并在APP层基于用户信息中的错误码，得到北斗网络设备200解析应用层报文的结果。进一步的，终端100可以针对不同的结果执行相应的操作。具体的，终端100执行的操作的详细描述可以参见图7所述实施例，在此不再赘述。
其中，当接收设备为终端100时，回执帧的具体描述可以参见图10所述实施例。
接下来介绍本申请实施例提供的一种终端100发送回执帧的示例。
如图10所示，首先，终端100可以将解析应用层报文的结果下发至SLC层。在SLC层，终端100可以将解析应用层报文的结果对应的应用层回执信息写入用户信息。其中，应用层回执信息可以为错误码。错误码可以用于指示终端100解析应用层报文的结果，其中，错误码的详细描述可以参见上述图9所述实施例，在此不再赘述。
之后，终端100可以在用户信息前添加帧头信息，得到回执帧。其中，帧头信息可以包括但不限于版本号字段、子类型指示字段、用户ID字段、帧总数字段、帧序号字段、SAI字段、保留域(reserve，RSV)字段等等。
其中，SAI字段、帧总数字段、帧序号字段的文字描述可以参见上述图2A所述实施例，在此不再赘述。
其中，版本号字段可以用于标识北斗短报文协议的版本。
子类型指示字段可以用于标识用户帧的类型。例如，子类型指示字段的长度可以为2bit。当子类型指示字段的值为00时，可以标识当前用户帧为通用数据帧。其中，通用数据帧可以包括但不限于紧急救援帧、位置报告帧、报文通信帧等等。当子类型指示字段的值为01时，可以标识当前用户帧为ACK帧。当子类型指示字段的值为10时，可以标识当前用户帧为回执帧。在此，北斗网络设备200向终端100发送回执帧，因此子类型指示字段的值可以为10。
用户ID字段可以用于标识接收应用层回执的设备(终端100)。
其中，保留域字段可以用于后续北斗通信系统的其他字段使用，在此不做限定。
之后，终端100可以将回执帧下发至PHY层。在PHY层，终端100可以将回执帧作为数据段，并在给数据段添加同步头和校验位后得到的对应的物理帧发送给北斗短报文卫星21，并经由北斗短报文卫星21中继转发给北斗网络设备200。
北斗网络设备200收到物理帧后，可以通过物理层处理(例如，解扩、解调、去导频、解码等操作)得到用户帧并将用户帧上传至SLC层。北斗网络设备200可以在SLC层通过子类型指示字段的值确定用户帧为回执帧后，北斗网络设备200可以将回执帧的错误码通过层间接口上传至APP层。北斗网络设备200在APP层可以基于回执帧的错误码获取终端100解析应用层报文的结果。
进一步的，北斗网络设备200还可以基于终端100解析应用层报文的结果执行相应的操作。具体的，可以参见上述图7所述实施例，在此不再赘述。
在本申请实施例中，上述回执帧处理机制仅为示例说明，本申请对回执帧处理机制的具体操作不作限定。
在一种可能的实现方式中，接收设备可以在APP层将应用层回执信息封装为应用层回执报文，之后，接收设备可以将应用层回执报文发送至发送设备。这样，可以沿用应用层报文的发送机制得到应用层回执报文，减少对北斗通信系统的处理机制的更改。
具体的，接收设备可以将应用层回执信息作为上述原始数据。首先，接收设备可以编码压缩应用层回执信息，得到压缩数据。再加密压缩数据得到加密后数据。之后，接收设备可以在加密后数据前添加报文头信息，得到应用层回执报文。
其中，报文头信息中可以包括但不限于加密指示字段、压缩指示字段和回执标识字段。其中，加密指示字段和压缩指示字段的描述可以参见上述图3A所述实施例，在此不再赘述。其中，回执标识字段可以用于指示应用层报文是否包括应用层回执信息。
示例性的，回执标识字段的长度可以为1bit。当回执标识字段的值为1时，应用层报文包括应用层回执信息。需要说明的是，可以将包括应用层回执信息的应用层报文简称为应用层回执报文。当回执标识字段的值为0时，应用层报文不包括应用层回执信息。
需要说明的是，接收设备生成应用层回执报文并将应用层回执报文发送至发送设备的流程和发送设备生成和发送应用层报文的流程相同。其中，具体的文字描述可以参见上述图2A或图3A所述实施例，在此不再赘述。发送设备得到应用层回执报文的原始数据的流程和上述接收设备得到应用层报文的原始数据的流程相同，具体的文字描述可以参见上述图2B或图3B所述实施例。
发送设备在得到应用层报文后，可以基于回执标识字段的值判断应用层报文是否为应用层回执报文。当发送设备确定出回执标识字段指示应用层报文为应用层回执报文时，发送设备可以基于原始数据(即，应用层回执信息)确定出接收设备解析应用层报文的结果，具体的文字描述可以参见上述图7所示实施例，在此不再赘述。
可选的，接收设备可以不压缩、加密原始数据，直接在应用层回执信息前添加报文头信息，得到应用层回执报文。其中，接收设备可以将报文头信息中压缩指示字段的值设置为不使用压缩算法，可以将报文头信息中加密指示字段的值设置为不使用加密算法。
进一步可选的，应用层回执报文的报文头信息中可以不包括压缩指示字段和加密指示字段。
下面具体介绍北斗通信系统10中的一种应用层的回执处理机制。
图11示出了本申请实施例中发送设备和接收设备间的另一种可能的应用层回执处理机制。
如图11所示，接收设备可以在接收到发送设备发送的应用层报文对应的最后一个SLC SDU的SLC PDU后，不发送SLC层的ACK，只向发送设备发送应用层回执信息。这样，发送设备在接收到应用层回执信息时，就可以证明接收设备收到了SLC SDU的所有SLC PDU，接收设备可以不再发送最后一个SLC SDU的SLC PDU的ACK，节约接收设备的空口资源。
S1101，发送设备生成应用层报文。
S1102，发送设备将应用层报文通过层间接口从APP层下发至MDCP层。
S1103，发送设备将应用层报文作为MDCP SDU，基于MDCP SDU得到M个MDCP PDU。
S1104，发送设备将MDCP PDU通过层间接口从MDCP层下发至SLC层。
S1105，发送设备将MDCP PDU作为SLC SDU，并将SLC SDU分帧为N个SLC PDU。
S1106，发送设备将SLC PDU发送至接收设备。
其中，步骤S1101至步骤S1106的详细描述可以参见上述图7所述实施例，在此不再赘述。
S1107，接收设备将SLC PDU拼接为SLC SDU。
S1108，接收设备将SLC SDU通过层间接口从SLC层上传至MDCP层。
S1109，接收设备可以将SLC SDU作为MDCP PDU，并基于MDCP PDU得到MDCP SDU。
S1110，接收设备可以将MDCP SDU通过层间接口从MDCP层上传至APP层。
在SLC层，接收设备可以在接收到SLC SDU的SLC PDU后，基于SLC PDU的帧头信息向发送设备回复ACK。若接收设备基于帧头信息判定出未接收到SLC SDU的所有SLC PDU，接收设备可以向发送设备发送第二ACK。其中，第二ACK可以用于指示接收设备未接收到SLC SDU的所有SLC PDU，且第二ACK还可以指示未接收到的SLC PDU的帧序号。 发送设备在收到第二ACK后，可以向接收设备重传第二ACK指示的未接收到的SLC PDU。
若接收设备基于帧头信息判定出已经接收到SLC SDU的所有SLC PDU，接收设备可以将SLC PDU拼接得到SLC SDU，并将SLC SDU上传至MDCP层。
在MDCP层，接收设备可以将SLC SDU作为MDCP PDU。接收设备可以基于MDCP PDU的后继指示字段判断当前MDCP PDU是否为MDCP SDU的最后一个MDCP PDU。
若接收设备基于后继指示字段判定出当前接收到的MDCP PDU不是MDCP SDU的所有MDCP PDU中的最后一个MDCP PDU，接收设备可以在SLC层发送第一ACK。当发送设备收到第一ACK后，可以向接收设备发送MDCP SDU的下一个MDCP PDU。
其中，接收设备可以在MDCP层向SLC层发送第一消息，第一消息可以用于指示接收设备在SLC层向发送设备发送第一ACK。
若接收设备基于后继指示字段判定出当前接收到的MDCP PDU是MDCP SDU的所有MDCP PDU中的最后一个MDCP PDU，接收设备可以将MDCP PDU按照接收顺序拼接为MDCP SDU，并将MDCP SDU上传至APP层。
需要说明的是，接收设备基于后继指示字段判定出当前接收到的MDCP PDU是MDCP SDU的所有MDCP PDU中的最后一个MDCP PDU后，不在SLC层发送第一ACK。其中，第一ACK用于指示接收设备在SLC层接收到当前发送的SLC SDU的所有SLC PDU。
S1111，接收设备将MDCP SUD作为应用层报文，解析应用层报文并基于解析应用层报文的结果生成应用层回执信息。
在APP层，接收设备可以将MDCP SDU作为应用层报文，并解析该应用层报文。接收设备可以在解析应用层报文后，基于解析应用层报文的结果生成对应的应用层回执信息。具体的，当接收设备为北斗网络设备200时，接收设备生成应用层回执信息的详细描述可以参见上述图9所述实施例，当接收设备为终端100时，接收设备生成应用层回执信息的详细描述可以参见上述图10所述实施例，在此不再赘述。
在此，应用层回执信息不止可以用于指示接收设备解析应用层报文的情况，还可以用于指示接收设备在SLC层收到最后一个SLC SDU的所有SLC PDU。
S1112，接收设备将应用层回执信息发送给发送设备。
具体的，发送设备得到应用层回执信息的流程可以参见上述图9至图10所示实施例，在此不再赘述。
发送设备收到应用层回执信息后，可以基于应用层回执信息确定出接收设备解析应用层报文的结果。进一步的，发送设备可以基于应用层回执信息执行相应的操作，具体描述可以参见上述图7所述实施例，在此不再赘述。
在一种可能的实现方式中，发送设备可以通过在报文头中添加回执指示字段指示接收设备是否反馈应用层回执信息。这样，可以由发送设备决定是否需要反馈应用层回执，在一些不需要应用层回执的情形下，节约接收设备反馈ACK的时间。
也就是说，在APP层，当接收设备判定出不回复应用层回执信息(例如回执指示字段的值为0)时，接收设备在SLC层向发送设备发送第一ACK。当接收设备判定出回复应用层回执信息(例如回执指示字段的值为0)时，接收设备可以解析得到应用层报文的原始数据，并基于解析应用层报文的结果生成应用层回执信息，再将应用层回执信息发送至发送设备。
在一种可能的实现方式中，接收设备基于回执指示字段判断是否回复应用层回执信息时， 接收设备可以在MDCP层解析回执指示字段，并基于回执指示字段的值判断是否回复应用层回执信息。这样，发送设备可以仅通过应用层回执信息就可以确定接收设备的SLC层的接收情况和接收设备解析应用层报文的情况。并且由于接收设备只反馈应用层回执信息，还可以节约接收设备的发送ACK帧所用的资源。
示例性的，在SLC层，接收设备可以在收到发送设备发送的SLC PDU后，基于SLC PDU的帧头信息回复ACK。
其中，若接收设备基于帧头信息判定出未接收到SLC SDU的所有SLC PDU，接收设备可以向发送设备发送第二ACK。其中，第二ACK可以用于指示接收设备未接收到SLC SDU的所有SLC PDU，且第二ACK还可以指示未接收到的SLC PDU的帧序号。发送设备在收到第二ACK后，可以向接收设备重传第二ACK指示的未接收到的SLC PDU。
若接收设备基于帧头信息判定出已经接收到SLC SDU的所有SLC PDU，接收设备可以将SLC PDU拼接得到SLC SDU，并将SLC SDU上传至MDCP层，作为MDCP PDU。
在MDCP层，接收设备可以基于MDCP PDU的后继指示字段判断当前MDCP PDU是否为MDCP SDU的最后一个MDCP PDU。
若接收设备基于后继指示字段判定出当前接收到的MDCP PDU不是MDCP SDU的所有MDCP PDU中的最后一个MDCP PDU，接收设备可以通知SLC层发送第一ACK。当发送设备收到第一ACK后，可以向接收设备发送MDCP SDU的下一个MDCP PDU。
若接收设备基于后继指示字段判定出当前接收到的MDCP PDU是MDCP SDU的所有MDCP PDU中的最后一个MDCP PDU，接收设备可以将MDCP PDU按照接收顺序拼接得到MDCP SDU。需要说明的时，当接收设备为北斗网络设备200时，北斗网络设备200可以基于冗余长度指示字段去除拼接后的MDCP PDU的填充数据，得到MDCP SDU。
在MDCP层，接收设备可以基于回执指示字段判断是否向发送设备回复应用层回执信息。
当接收设备判定出不回复应用层回执信息(例如回执指示字段的值为0)时，接收设备通知SLC层向发送设备发送第一ACK，并将MDCP SDU上传至APP层。在APP层，接收设备可以将MDCP SDU作为应用层报文，并解析该应用层报文。
当接收设备判定出回复应用层回执信息(例如回执指示字段的值为0)时，接收设备直接将MDCP SDU上传至APP层，并将MDCP SDU作为应用层报文进行解析。其中，接收设备可以同时通知APP层反馈应用层回执信息。接收设备可以基于解析应用层报文的结果生成对应的应用层回执信息。接收设备可以将应用层回执信息发送到发送设备。其中，当接收设备为北斗网络设备200时，接收设备生成应用层回执信息的详细描述可以参见上述图9所述实施例，当接收设备为终端100时，接收设备生成应用层回执信息的详细描述可以参见上述图10所述实施例，在此不再赘述。
发送设备收到应用层回执信息后，发送设备可以基于应用层回执信息确定出接收设备解析应用层报文的结果。其中，在此，应用层回执信息还可以等同于第一ACK，发送设备可以基于应用层回执信息确认接收设备接收到MDCP SDU的最后一个MDCP PDU对应的所有SLC PDU。
在一些可能的实施例中，接收设备可以预设为向发送设备回复应用层回执信息。这样，不需要基于回执指示字段判断，接收设备自动回复应用层回执信息。
下面介绍本申请实施例提供的终端100。
终端100可以是手机、平板电脑、桌面型计算机、膝上型计算机、手持计算机、笔记本 电脑、超级移动个人计算机(ultra-mobile personal computer，UMPC)、上网本，以及蜂窝电话、个人数字助理(personal digital assistant，PDA)、增强现实(augmented reality，AR)设备、虚拟现实(virtual reality，VR)设备、人工智能(artificial intelligence,AI)设备、可穿戴式设备、车载设备、智能家居设备和/或智慧城市设备，本申请实施例对该电子设备的具体类型不作特殊限制。
图12示出了本申请实施例提供的一种硬件结构示意图。
下面以终端100为例对实施例进行具体说明。应该理解的是，图12所示终端100仅是一个范例，并且终端100可以具有比图12中所示的更多的或者更少的部件，可以组合两个或多个的部件，或者可以具有不同的部件配置。图12中所示出的各种部件可以在包括一个或多个信号处理和/或专用集成电路在内的硬件、软件、或硬件和软件的组合中实现。
终端100可以包括：处理器110，外部存储器接口120，内部存储器121，通用串行总线(universal serial bus，USB)接口130，充电管理模块140，电源管理模块141，电池142，天线1，天线2，移动通信模块150，无线通信模块160，音频模块170，扬声器170A，受话器170B，麦克风170C，耳机接口170D，传感器模块180，按键190，马达191，指示器192，摄像头193，显示屏194，以及用户标识模块(subscriber identification module，SIM)卡接口195等。其中传感器模块180可以包括压力传感器180A，陀螺仪传感器180B，气压传感器180C，磁传感器180D，加速度传感器180E，距离传感器180F，接近光传感器180G，指纹传感器180H，温度传感器180J，触摸传感器180K，环境光传感器180L，骨传导传感器180M等。
可以理解的是，本发明实施例示意的结构并不构成对终端100的具体限定。在本申请另一些实施例中，终端100可以包括比图示更多或更少的部件，或者组合某些部件，或者拆分某些部件，或者不同的部件布置。图示的部件可以以硬件，软件或软件和硬件的组合实现。
处理器110可以包括一个或多个处理单元，例如：处理器110可以包括应用处理器(application processor，AP)，调制解调处理器，图形处理器(graphics processing unit，GPU)，图像信号处理器(image signal processor，ISP)，控制器，存储器，视频编解码器，数字信号处理器(digital signal processor，DSP)，基带处理器，和/或神经网络处理器(neural-network processing unit，NPU)等。其中，不同的处理单元可以是独立的器件，也可以集成在一个或多个处理器中。
其中，控制器可以是终端100的神经中枢和指挥中心。控制器可以根据指令操作码和时序信号，产生操作控制信号，完成取指令和执行指令的控制。
处理器110中还可以设置存储器，用于存储指令和数据。在一些实施例中，处理器110中的存储器为高速缓冲存储器。该存储器可以保存处理器110刚用过或循环使用的指令或数据。如果处理器110需要再次使用该指令或数据，可从所述存储器中直接调用。避免了重复存取，减少了处理器110的等待时间，因而提高了系统的效率。
在一些实施例中，处理器110可以包括一个或多个接口。接口可以包括集成电路(inter-integrated circuit，I2C)接口，集成电路内置音频(inter-integrated circuit sound，I2S)接口，脉冲编码调制(pulse code modulation，PCM)接口，通用异步收发传输器(universal asynchronous receiver/transmitter，UART)接口，移动产业处理器接口(mobile industry processor interface，MIPI)，通用输入输出(general-purpose input/output，GPIO)接口，用户标识模块(subscriber identity module，SIM)接口，和/或通用串行总线(universal serial bus，USB)接口等。
I2C接口是一种双向同步串行总线，包括一根串行数据线(serial data line，SDA)和一根串行时钟线(derail clock line，SCL)。在一些实施例中，处理器110可以包含多组I2C总线。处 理器110可以通过不同的I2C总线接口分别耦合触摸传感器180K，充电器，闪光灯，摄像头193等。例如：处理器110可以通过I2C接口耦合触摸传感器180K，使处理器110与触摸传感器180K通过I2C总线接口通信，实现终端100的触摸功能。
I2S接口可以用于音频通信。在一些实施例中，处理器110可以包含多组I2S总线。处理器110可以通过I2S总线与音频模块170耦合，实现处理器110与音频模块170之间的通信。在一些实施例中，音频模块170可以通过I2S接口向无线通信模块160传递音频信号，实现通过蓝牙耳机接听电话的功能。
PCM接口也可以用于音频通信，将模拟信号抽样，量化和编码。在一些实施例中，音频模块170与无线通信模块160可以通过PCM总线接口耦合。在一些实施例中，音频模块170也可以通过PCM接口向无线通信模块160传递音频信号，实现通过蓝牙耳机接听电话的功能。所述I2S接口和所述PCM接口都可以用于音频通信。
UART接口是一种通用串行数据总线，用于异步通信。该总线可以为双向通信总线。它将要传输的数据在串行通信与并行通信之间转换。在一些实施例中，UART接口通常被用于连接处理器110与无线通信模块160。例如：处理器110通过UART接口与无线通信模块160中的蓝牙模块通信，实现蓝牙功能。在一些实施例中，音频模块170可以通过UART接口向无线通信模块160传递音频信号，实现通过蓝牙耳机播放音乐的功能。
MIPI接口可以被用于连接处理器110与显示屏194，摄像头193等外围器件。MIPI接口包括摄像头串行接口(camera serial interface，CSI)，显示屏串行接口(display serial interface，DSI)等。在一些实施例中，处理器110和摄像头193通过CSI接口通信，实现终端100的拍摄功能。处理器110和显示屏194通过DSI接口通信，实现终端100的显示功能。
GPIO接口可以通过软件配置。GPIO接口可以被配置为控制信号，也可被配置为数据信号。在一些实施例中，GPIO接口可以用于连接处理器110与摄像头193，显示屏194，无线通信模块160，音频模块170，传感器模块180等。GPIO接口还可以被配置为I2C接口，I2S接口，UART接口，MIPI接口等。
USB接口130是符合USB标准规范的接口，具体可以是Mini USB接口，Micro USB接口，USB Type C接口等。USB接口130可以用于连接充电器为终端100充电，也可以用于终端100与外围设备之间传输数据。也可以用于连接耳机，通过耳机播放音频。该接口还可以用于连接其他电子设备，例如AR设备等。
可以理解的是，本发明实施例示意的各模块间的接口连接关系，只是示意性说明，并不构成对终端100的结构限定。在本申请另一些实施例中，终端100也可以采用上述实施例中不同的接口连接方式，或多种接口连接方式的组合。
充电管理模块140用于从充电器接收充电输入。其中，充电器可以是无线充电器，也可以是有线充电器。在一些有线充电的实施例中，充电管理模块140可以通过USB接口130接收有线充电器的充电输入。在一些无线充电的实施例中，充电管理模块140可以通过终端100的无线充电线圈接收无线充电输入。充电管理模块140为电池142充电的同时，还可以通过电源管理模块141为电子设备供电。
电源管理模块141用于连接电池142，充电管理模块140与处理器110。电源管理模块141接收电池142和/或充电管理模块140的输入，为处理器110，内部存储器121，外部存储器，显示屏194，摄像头193，和无线通信模块160等供电。电源管理模块141还可以用于监测电池容量，电池循环次数，电池健康状态(漏电，阻抗)等参数。在其他一些实施例中，电源管理模块141也可以设置于处理器110中。在另一些实施例中，电源管理模块141和充电 管理模块140也可以设置于同一个器件中。
终端100的无线通信功能可以通过天线1，天线2，移动通信模块150，无线通信模块160，调制解调处理器以及基带处理器等实现。
天线1和天线2用于发射和接收电磁波信号。终端100中的每个天线可用于覆盖单个或多个通信频带。不同的天线还可以复用，以提高天线的利用率。例如：可以将天线1复用为无线局域网的分集天线。在另外一些实施例中，天线可以和调谐开关结合使用。
移动通信模块150可以提供应用在终端100上的包括2G/3G/4G/5G等无线通信的解决方案。移动通信模块150可以包括至少一个滤波器，开关，功率放大器，低噪声放大器(low noise amplifier，LNA)等。移动通信模块150可以由天线1接收电磁波，并对接收的电磁波进行滤波，放大等处理，传送至调制解调处理器进行解调。移动通信模块150还可以对经调制解调处理器调制后的信号放大，经天线1转为电磁波辐射出去。在一些实施例中，移动通信模块150的至少部分功能模块可以被设置于处理器110中。在一些实施例中，移动通信模块150的至少部分功能模块可以与处理器110的至少部分模块被设置在同一个器件中。
调制解调处理器可以包括调制器和解调器。其中，调制器用于将待发送的低频基带信号调制成中高频信号。解调器用于将接收的电磁波信号解调为低频基带信号。随后解调器将解调得到的低频基带信号传送至基带处理器处理。低频基带信号经基带处理器处理后，被传递给应用处理器。应用处理器通过音频设备(不限于扬声器170A，受话器170B等)输出声音信号，或通过显示屏194显示图像或视频。在一些实施例中，调制解调处理器可以是独立的器件。在另一些实施例中，调制解调处理器可以独立于处理器110，与移动通信模块150或其他功能模块设置在同一个器件中。
无线通信模块160可以提供应用在终端100上的包括无线局域网(wireless local area networks，WLAN)(如无线保真(wireless fidelity，Wi-Fi)网络)，蓝牙(bluetooth，BT)，全球导航卫星系统(global navigation satellite system，GNSS)，卫星通信模块，调频(frequency modulation，FM)，近距离无线通信技术(near field communication，NFC)，红外技术(infrared，IR)等无线通信的解决方案。无线通信模块160可以是集成至少一个通信处理模块的一个或多个器件。无线通信模块160经由天线2接收电磁波，将电磁波信号调频以及滤波处理，将处理后的信号发送到处理器110。无线通信模块160还可以从处理器110接收待发送的信号，对其进行调频，放大，经天线2转为电磁波辐射出去。
其中，卫星通信模块可用于与卫星网络设备进行通信，例如在北斗通信系统中，卫星通信模块可以与北斗网络设备200通信，卫星通信模块的可支持与北斗网络设备200之间的短报文传输。
在一些实施例中，终端100的天线1和移动通信模块150耦合，天线2和无线通信模块160耦合，使得终端100可以通过无线通信技术与网络以及其他设备通信。所述无线通信技术可以包括全球移动通讯系统(global system for mobile communications，GSM)，通用分组无线服务(general packet radio service，GPRS)，码分多址接入(code division multiple access，CDMA)，宽带码分多址(wideband code division multiple access，WCDMA)，时分码分多址(time-division code division multiple access，TD-SCDMA)，长期演进(long term evolution，LTE)，BT，GNSS，WLAN，NFC，FM，和/或IR技术等。所述GNSS可以包括全球卫星定位系统(global positioning system，GPS)，全球导航卫星系统(global navigation satellite system，GLONASS)，北斗卫星导航系统(beidou navigation satellite system，BDS)，准天顶卫星系统(quasi-zenith satellite system，QZSS)和/或星基增强系统(satellite based augmentation systems， SBAS)。
终端100通过GPU，显示屏194，以及应用处理器等实现显示功能。GPU为图像处理的微处理器，连接显示屏194和应用处理器。GPU用于执行数学和几何计算，用于图形渲染。处理器110可包括一个或多个GPU，其执行程序指令以生成或改变显示信息。
显示屏194用于显示图像，视频等。显示屏194包括显示面板。显示面板可以采用液晶显示屏(liquid crystal display，LCD)，有机发光二极管(organic light-emitting diode，OLED)，有源矩阵有机发光二极体或主动矩阵有机发光二极体(active-matrix organic light emitting diode的，AMOLED)，柔性发光二极管(flex light-emitting diode，FLED)，Miniled，MicroLed，Micro-oLed，量子点发光二极管(quantum dot light emitting diodes，QLED)等。在一些实施例中，终端100可以包括1个或N个显示屏194，N为大于1的正整数。
终端100可以通过ISP，摄像头193，视频编解码器，GPU，显示屏194以及应用处理器等实现拍摄功能。
ISP用于处理摄像头193反馈的数据。例如，拍照时，打开快门，光线通过镜头被传递到摄像头感光元件上，光信号转换为电信号，摄像头感光元件将所述电信号传递给ISP处理，转化为肉眼可见的图像。ISP还可以对图像的噪点，亮度进行算法优化。ISP还可以对拍摄场景的曝光，色温等参数优化。在一些实施例中，ISP可以设置在摄像头193中。
摄像头193用于捕获静态图像或视频。物体通过镜头生成光学图像投射到感光元件。感光元件可以是电荷耦合器件(charge coupled device，CCD)或互补金属氧化物半导体(complementary metal-oxide-semiconductor，CMOS)光电晶体管。感光元件把光信号转换成电信号，之后将电信号传递给ISP转换成数字图像信号。ISP将数字图像信号输出到DSP加工处理。DSP将数字图像信号转换成标准的RGB，YUV等格式的图像信号。在一些实施例中，终端100可以包括1个或N个摄像头193，N为大于1的正整数。
数字信号处理器用于处理数字信号，除了可以处理数字图像信号，还可以处理其他数字信号。例如，当终端100在频点选择时，数字信号处理器用于对频点能量进行傅里叶变换等。
视频编解码器用于对数字视频压缩或解压缩。终端100可以支持一种或多种视频编解码器。这样，终端100可以播放或录制多种编码格式的视频，例如：动态图像专家组(moving picture experts group，MPEG)1，MPEG2，MPEG3，MPEG4等。
NPU为神经网络(neural-network，NN)计算处理器，通过借鉴生物神经网络结构，例如借鉴人脑神经元之间传递模式，对输入信息快速处理，还可以不断的自学习。通过NPU可以实现终端100的智能认知等应用，例如：图像识别，人脸识别，语音识别，文本理解等。
外部存储器接口120可以用于连接外部存储卡，例如Micro SD卡，实现扩展终端100的存储能力。外部存储卡通过外部存储器接口120与处理器110通信，实现数据存储功能。例如将音乐，视频等文件保存在外部存储卡中。
内部存储器121可以用于存储计算机可执行程序代码，所述可执行程序代码包括指令。处理器110通过运行存储在内部存储器121的指令，从而执行终端100的各种功能应用以及数据处理。内部存储器121可以包括存储程序区和存储数据区。其中，存储程序区可存储操作系统，至少一个功能所需的应用程序(比如声音播放功能，图像播放功能等)等。存储数据区可存储终端100使用过程中所创建的数据(比如音频数据，电话本等)等。此外，内部存储器121可以包括高速随机存取存储器，还可以包括非易失性存储器，例如至少一个磁盘存储器件，闪存器件，通用闪存存储器(universal flash storage，UFS)等。
终端100可以通过音频模块170，扬声器170A，受话器170B，麦克风170C，耳机接口 170D，以及应用处理器等实现音频功能。例如音乐播放，录音等。
音频模块170用于将数字音频信息转换成模拟音频信号输出，也用于将模拟音频输入转换为数字音频信号。音频模块170还可以用于对音频信号编码和解码。在一些实施例中，音频模块170可以设置于处理器110中，或将音频模块170的部分功能模块设置于处理器110中。
扬声器170A，也称“喇叭”，用于将音频电信号转换为声音信号。终端100可以通过扬声器170A收听音乐，或收听免提通话。
受话器170B，也称“听筒”，用于将音频电信号转换成声音信号。当终端100接听电话或语音信息时，可以通过将受话器170B靠近人耳接听语音。
麦克风170C，也称“话筒”，“传声器”，用于将声音信号转换为电信号。当拨打电话或发送语音信息时，用户可以通过人嘴靠近麦克风170C发声，将声音信号输入到麦克风170C。终端100可以设置至少一个麦克风170C。在另一些实施例中，终端100可以设置两个麦克风170C，除了采集声音信号，还可以实现降噪功能。在另一些实施例中，终端100还可以设置三个，四个或更多麦克风170C，实现采集声音信号，降噪，还可以识别声音来源，实现定向录音功能等。
耳机接口170D用于连接有线耳机。耳机接口170D可以是USB接口130，也可以是3.5mm的开放移动电子设备平台(open mobile terminal platform，OMTP)标准接口，美国蜂窝电信工业协会(cellular telecommunications industry association of the USA，CTIA)标准接口。
压力传感器180A用于感受压力信号，可以将压力信号转换成电信号。在一些实施例中，压力传感器180A可以设置于显示屏194。压力传感器180A的种类很多，如电阻式压力传感器，电感式压力传感器，电容式压力传感器等。电容式压力传感器可以是包括至少两个具有导电材料的平行板。当有力作用于压力传感器180A，电极之间的电容改变。终端100根据电容的变化确定压力的强度。当有触摸操作作用于显示屏194，终端100根据压力传感器180A检测所述触摸操作强度。终端100也可以根据压力传感器180A的检测信号计算触摸的位置。在一些实施例中，作用于相同触摸位置，但不同触摸操作强度的触摸操作，可以对应不同的操作指令。例如：当有触摸操作强度小于第一压力阈值的触摸操作作用于短消息应用图标时，执行查看短消息的指令。当有触摸操作强度大于或等于第一压力阈值的触摸操作作用于短消息应用图标时，执行新建短消息的指令。
陀螺仪传感器180B可以用于确定终端100的运动姿态。在一些实施例中，可以通过陀螺仪传感器180B确定终端100围绕三个轴(即，x，y和z轴)的角速度。陀螺仪传感器180B可以用于拍摄防抖。示例性的，当按下快门，陀螺仪传感器180B检测终端100抖动的角度，根据角度计算出镜头模组需要补偿的距离，让镜头通过反向运动抵消终端100的抖动，实现防抖。陀螺仪传感器180B还可以用于导航，体感游戏场景。
气压传感器180C用于测量气压。在一些实施例中，终端100通过气压传感器180C测得的气压值计算海拔高度，辅助定位和导航。
磁传感器180D包括霍尔传感器。终端100可以利用磁传感器180D检测翻盖皮套的开合。在一些实施例中，当终端100是翻盖机时，终端100可以根据磁传感器180D检测翻盖的开合。进而根据检测到的皮套的开合状态或翻盖的开合状态，设置翻盖自动解锁等特性。
加速度传感器180E可检测终端100在各个方向上(一般为三轴)加速度的大小。当终端100静止时可检测出重力的大小及方向。还可以用于识别电子设备姿态，应用于横竖屏切换，计步器等应用。
距离传感器180F，用于测量距离。终端100可以通过红外或激光测量距离。在一些实施例中，拍摄场景，终端100可以利用距离传感器180F测距以实现快速对焦。
接近光传感器180G可以包括例如发光二极管(LED)和光检测器，例如光电二极管。发光二极管可以是红外发光二极管。终端100通过发光二极管向外发射红外光。终端100使用光电二极管检测来自附近物体的红外反射光。当检测到充分的反射光时，可以确定终端100附近有物体。当检测到不充分的反射光时，终端100可以确定终端100附近没有物体。终端100可以利用接近光传感器180G检测用户手持终端100贴近耳朵通话，以便自动熄灭屏幕达到省电的目的。接近光传感器180G也可用于皮套模式，口袋模式自动解锁与锁屏。
环境光传感器180L用于感知环境光亮度。终端100可以根据感知的环境光亮度自适应调节显示屏194亮度。环境光传感器180L也可用于拍照时自动调节白平衡。环境光传感器180L还可以与接近光传感器180G配合，检测终端100是否在口袋里，以防误触。
指纹传感器180H用于采集指纹。终端100可以利用采集的指纹特性实现指纹解锁，访问应用锁，指纹拍照，指纹接听来电等。
温度传感器180J用于检测温度。在一些实施例中，终端100利用温度传感器180J检测的温度，执行温度处理策略。例如，当温度传感器180J上报的温度超过阈值，终端100执行降低位于温度传感器180J附近的处理器的性能，以便降低功耗实施热保护。在另一些实施例中，当温度低于另一阈值时，终端100对电池142加热，以避免低温导致终端100异常关机。在其他一些实施例中，当温度低于又一阈值时，终端100对电池142的输出电压执行升压，以避免低温导致的异常关机。
触摸传感器180K，也称“触控面板”。触摸传感器180K可以设置于显示屏194，由触摸传感器180K与显示屏194组成触摸屏，也称“触控屏”。触摸传感器180K用于检测作用于其上或附近的触摸操作。触摸传感器可以将检测到的触摸操作传递给应用处理器，以确定触摸事件类型。可以通过显示屏194提供与触摸操作相关的视觉输出。在另一些实施例中，触摸传感器180K也可以设置于终端100的表面，与显示屏194所处的位置不同。
骨传导传感器180M可以获取振动信号。在一些实施例中，骨传导传感器180M可以获取人体声部振动骨块的振动信号。骨传导传感器180M也可以接触人体脉搏，接收血压跳动信号。在一些实施例中，骨传导传感器180M也可以设置于耳机中，结合成骨传导耳机。音频模块170可以基于所述骨传导传感器180M获取的声部振动骨块的振动信号，解析出语音信号，实现语音功能。应用处理器可以基于所述骨传导传感器180M获取的血压跳动信号解析心率信息，实现心率检测功能。
按键190包括开机键，音量键等。按键190可以是机械按键。也可以是触摸式按键。终端100可以接收按键输入，产生与终端100的用户设置以及功能控制有关的键信号输入。
马达191可以产生振动提示。马达191可以用于来电振动提示，也可以用于触摸振动反馈。例如，作用于不同应用(例如拍照，音频播放等)的触摸操作，可以对应不同的振动反馈效果。作用于显示屏194不同区域的触摸操作，马达191也可对应不同的振动反馈效果。不同的应用场景(例如：时间提醒，接收信息，闹钟，游戏等)也可以对应不同的振动反馈效果。触摸振动反馈效果还可以支持自定义。
指示器192可以是指示灯，可以用于指示充电状态，电量变化，也可以用于指示消息，未接来电，通知等。
SIM卡接口195用于连接SIM卡。SIM卡可以通过插入SIM卡接口195，或从SIM卡接口195拔出，实现和终端100的接触和分离。终端100可以支持1个或N个SIM卡接口，N 为大于1的正整数。SIM卡接口195可以支持Nano SIM卡，Micro SIM卡，SIM卡等。同一个SIM卡接口195可以同时插入多张卡。所述多张卡的类型可以相同，也可以不同。SIM卡接口195也可以兼容不同类型的SIM卡。SIM卡接口195也可以兼容外部存储卡。终端100通过SIM卡和网络交互，实现通话以及数据通信等功能。在一些实施例中，终端100采用eSIM，即：嵌入式SIM卡。eSIM卡可以嵌在终端100中，不能和终端100分离。
下面介绍本申请实施例中提供的一种北斗通信系统中应用层回执传输方法。
图13示出了本申请实施例中提供的一种北斗通信系统中应用层回执传输方法的流程示意图。
如图13所示，该北斗通信系统中应用层回执传输方法包括如下步骤：
S1301、发送设备向接收设备发送第一应用层报文的第一MDCP PDU。
其中，第一MDCP PDU的包头信息包括后继指示字段，后继指示字段用于指第一MDCP PDU在所述第一应用层报文中的顺序。具体有关MDCP PDU的描述可以参考前述实施例，在此不再赘述。
S1302、接收设备基于第一MDCP PDU得到第一应用层报文。
在接收设备确定出第一MDCP PDU为第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，接收设备基于第一MDCP PDU得到第一应用层报文。其中，M为正整数。具体涉及基于MDCP PDU得到第一应用层报文的描述可以参考前述图2B、图3B所示实施例，在此不再赘述。
S1303、接收设备生成第一应用层回执信息。
其中，第一应用层回执信息用于指示接收设备解析第一应用层报文的结果。
具体涉及生成第一应用层回执信息的流程可以参考前述所示实施例，在此不再赘述。
S1304、接收设备将第一应用层回执信息发送给发送设备。
具体有关接收设备如何生成第一应用层回执信息，可以参考前述图7-图11所述实施例，在此不再赘述。
具体涉及发送设备发送应用层报文，发送设备基于第一应用层回执信息执行的操作可以参考前述图7-图11所示实施例，在此不再赘述。
下面介绍发送设备执行的一些可能的实现方式。
在一种可能的实现方式中，发送设备发送第一应用层报文中的第一MDCP PDU给接收设备，具体包括：
发送设备将第一MDCP PDU作为发送设备的SLC层的第一卫星链路控制层服务数据单元SLC SDU，从发送设备的MDCP层下发至发送设备的SLC层。
发送设备在发送设备的SLC层将第一SLC SDU拆分成N个卫星链路控制层协议数据单元SLC PDU，N为正整数。其中，N个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括帧总数字段和帧序号字段。帧总数字段用于指示第一SLC SDU中包括的SLC PDU的总数量N，帧序号字段用于指示第一SLC PDU在第一SLC SDU中的帧序号。
发送设备将N个SLC PDU发送给接收设备。
具体内容，可以参考前述图4所示实施例，在此不再赘述。
在一种可能的实现方式中，第一应用层回执信息还用于指示接收设备已收齐第一SLC SDU中的N个SLC PDU。这样，发送设备可以通过第一应用层回执信息判定出接收设备接收到应用层报文对应的所有SLC PDU。
具体内容，可以参考前述图11所示实施例，在此不再赘述。
在一种可能的实现方式中，发送设备接收到接收设备发送的第一应用层回执信息之前，方法还包括：发送设备接收到接收设备发送的第一确认字符ACK。其中，第一ACK用于指示接收设备已收齐第一SLC SDU中的N个SLC PDU。
具体内容，可以参考前述图7所示实施例，在此不再赘述。
在一种可能的实现方式中，发送设备接收到接收设备发送的第一应用层回执信息之前，方法还包括：发送设备接收到接收设备发送的第二确认字符ACK。其中，第一ACK用于指示第一SLC SDU中接收设备未接收到的SLC PDU的帧序号。
发送设备重传第一SLC SDU中接收设备未接收到的SLC PDU给接收设备。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
这样，可以保证接收设备可以得到完整的应用层报文。
在一种可能的实现方式中，发送设备将N个SLC PDU发送给接收设备，具体包括：发送设备将所第一SLC PDU从发送设备的SLC层下发至物理PHY层，作为发送设备的PHY层的第一用户帧。
发送设备针对第一用户帧进行物理层处理得到第一入站数据。
发送设备将第一入站数据发送给接收设备。
具体内容，可以参考前述图2A、图3A所示实施例，在此不再赘述。
在一种可能的实现方式中，发送设备发送第一应用层报文中的第一MDCP PDU给接收设备之前，方法还包括：发送设备在消息数据汇聚MDCP层获取到发送设备的应用层下发的第一应用层报文。
发送设备在MDCP层将第一应用层报文作为MDCP SDU，并将MDCP SDU拆分成M个MDCP PDU。其中，M为正整数。M个MDCP PDU中包括第一MDCP PDU。
具体内容，可以参考前述图2A、图3A所示实施例，在此不再赘述。
在一种可能的实现方式中，方法还包括：发送设备将M个MDCP PDU从MDCP层下发至SLC层，作为SLC层的M个SLC SDU，M个SLC SDU包括第一SLC SDU。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，在发送设备在MDCP层获取到发送设备的应用层下发的第一应用层报文之前，方法还包括：发送设备获取原始数据。
发送设备在应用层将原始数据，进行编码压缩得到第一压缩数据。
发送设备在应用层将第一压缩数据进行加密得到第一加密后数据。
发送设备在第一加密后数据头部加上报文头信息，得到第一应用层报文。其中，报文头信息包括压缩指示字段和加密指示字段，压缩指示字段用于指示对原始数据压缩时使用的编 码压缩算法，加密指示字段用于指示对第一压缩数据加密时使用的加密算法。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，发送设备接收到接收设备发送的第一应用层回执信息之后，方法还包括：发送设备基于第一应用层回执信息确定接收设备解析第一应用层报文失败，发送设备向接收设备重传第一应用层报文。
具体内容，可以参考前述图7所示实施例，在此不再赘述。
这样，发送设备在确定接收设备解析应用层报文失败时，可以再次发送应用层报文，避免因为传输过程中的数据错误导致接收设备解析应用层报文失败的情形。
在一种可能的实现方式中，第一应用层回执信息包括第一解析结果，其中，第一解析结果用于指示接收设备解密第一应用层报文失败。发送设备接收到接收设备发送的第一应用层回执信息之后，方法还包括：发送设备与接收设备协商密钥信息。
发送设备基于协商后的密钥信息加密第一压缩数据得到第二加密后数据。
发送设备将包括有第二加密后数据的第二应用层报文发送到接收设备。
具体内容，可以参考前述图7所示实施例，在此不再赘述。
在一种可能的实现方式中，第一应用层回执信息包括第二解析结果，其中，第二解析结果用于指示接收设备解码解压缩应用层报文失败。发送设备接收到接收设备发送的第一应用层回执信息之后，方法还包括：发送设备基于第二解析结果和接收设备协商码本。
发送设备基于协商后的码本编码压缩原始数据得到第二压缩数据。
发送设备将第二压缩数据加密，得到第三加密后数据。
发送设备将第三应用层报文发送给接收设备，第三应用层报文包括第三加密后数据。
具体内容，可以参考前述图7所示实施例，在此不再赘述。
在一种可能的实现方式中，上述发送设备为终端，接收设备为北斗网络设备。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，上述发送设备为北斗网络设备，接收设备为终端。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
下面介绍接收设备执行的一些可能的实现方式。
在一种可能的实现方式中，在接收设备生成第一应用层回执信息之前，方法还包括：接收设备对第一应用层报文中的第一加密后数据进行解密，并在解密成功后得到第一压缩数据。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，在接收设备对第一应用层报文中的第一加密后数据进行解密，并在解密成功后得到第一压缩数据之后，方法还包括：接收设备对第一压缩数据进行解码解压缩得到原始数据。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，在接收设备生成第一应用层回执信息之前，方法还包括：接收设备对第一加密后数据解密失败。
接收设备生成第一应用层回执信息。其中，第一应用层回执信息包括第一解析结果，第一解析结果用于指示接收设备解密失败。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
这样，接收设备可以在解密失败时，生成用于指示接收设备解密应用层报文失败的应用层回执信息。
在一种可能的实现方式中，在接收设备生成第一应用层回执信息之前，方法还包括：接收设备对第一压缩数据解码解压缩失败。
接收设备生成第一应用层回执信息。其中，第一应用层回执信息包括第二解析结果，第二解析结果用于指示接收设备解码失败。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
这样，接收设备可以在解码失败时，生成用于指示接收设备解码应用层报文失败的应用层回执信息。
在一种可能的实现方式中，第一应用层回执信息包括第三解析结果，第三解析结果用于指示接收设备解析应用层报文成功。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
这样，接收设备可以在解析成功时，生成用于指示接收设备解析应用层报文成功的应用层回执信息。
在一种可能的实现方式中，方法还包括：接收设备为北斗网络设备200时，可以将原始数据通过蜂窝网络发送给蜂窝用户设备。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
这样，接收设备可以在解析成功时，将数据转发到蜂窝网络下的用户设备。
在一种可能的实现方式中，接收设备接收到发送设备发送的第一应用层报文的第一MDCP PDU之前，方法还包括：接收设备在PHY层获取到发送设备发送的第一入站数据。
接收设备基于第一入站数据执行物理层处理得到第一用户帧。
接收设备将第一用户帧作为接收设备的SLC层中的第一SLC PDU，从PHY层呈递给接收设备的SLC层。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，在接收设备将第一用户帧作为接收设备的SLC层中的第一SLC PDU，从PHY层呈递给接收设备的SLC层之后，方法还包括：接收设备接收到发送设备发送的第一SLC SDU中的X个SLC PDU，X为正整数。其中，X个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括帧总数字段和帧序号字段。帧总数字段用于指示第一SLC SDU中包括SLC PDU的总数量N，N为正整数，帧序号字段用于指示第一SLC PDU在第一SLC SDU中的帧序号。
当X小于N时，接收设备向发送设备发送第二ACK，其中，第二ACK用于指示第一 SLC SDU中接收设备未接收到的SLC PDU的帧序号。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
这样，接收设备可以通知发送设备重传丢失的SLC PDU。
在一种可能的实现方式中，当接收设备接收到发送设备发送的第一SLC SDU中的X个SLC PDU后，方法还包括：当X等于N时，接收设备在SLC层将X个SLC PDU拼接成第一SLC SDU，并将第一SLC SDU作为MDCP层的第一MDCP PDU从接收设备的SLC层上报给接收设备的MDCP层。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，当接收设备接收到发送设备发送的第一SLC SDU中的X个SLC PDU后，方法还包括：当X等于N时，接收设备向发送设备发送第一ACK，其中，第一ACK用于指示接收设备已收齐第一SLC SDU中的N个SLC PDU。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，在接收设备确定出第一MDCP PDU为应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，接收设备基于第一MDCP PDU得到应用层报文，具体包括：接收设备在MDCP层将M个MDCP PDU拼接得到MDCP SDU，并将MDCP SDU作为应用层报文从MDCP层上报给应用层。
具体内容，可以参考前述图7、图11所示实施例，在此不再赘述。
在一种可能的实现方式中，接收设备将第一应用层回执信息发送至发送设备，具体包括：接收设备将第一应用层回执信息从接收设备的应用层经过预设接口发送至接收设备的SLC层。
接收设备在SLC层给第一应用层回执信息添加帧头信息后，将添加了帧头信息的第一应用层回执信息下发至物理层，得到回执帧。其中，帧头信息包括帧类型字段，帧类型字段用于指示用户帧的帧类型。
接收设备将回执帧发送至发送设备。
具体内容，可以参考前述图7-图11所示实施例，在此不再赘述。
在一种可能的实现方式中，接收设备将第一应用层回执信息发送至发送设备，具体包括：
接收设备将第一应用层回执信息封装为应用层回执报文，并将该应用层回执报文发送给发送设备，
具体内容，可以参考前述图7-图11所示实施例，在此不再赘述。
在一种可能的实现方式中，上述发送设备为终端，接收设备为北斗网络设备。
具体内容，可以参考前述图7-图11所示实施例，在此不再赘述。
在一种可能的实现方式中，上述发送设备为北斗网络设备，接收设备为终端。
具体内容，可以参考前述图7-图11所示实施例，在此不再赘述。
上述内容详细阐述了本申请提供的方法，为了便于更好地实施本申请实施例的上述方案， 本申请实施例还提供了相应的装置或设备。
本申请实施例可以根据上述方法示例对终端100和北斗网络设备200进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。需要说明的是，本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
下面将结合图14至图17详细描述本申请实施例的通信装置。
在采用集成的单元的情况下，参见图14，图14是本申请实施例提供的通信装置1400的结构示意图。该通信装置1400可以为上述实施例中的终端100。可选的，通信装置1400可以为一种芯片/芯片系统，例如，北斗通信芯片。如图14所示，该通信装置1400可以包括收发单元1410和处理单元1420。
在入站的一种设计中，收发单元1410，可用于向北斗网络设备200发送第一应用层报文中的第一MDCP PDU。其中，第一MDCP PDU的包头信息包括后继指示字段。后继指示字段用于指示第一MDCP PDU在第一应用层报文中的顺序。
收发单元1410，可用于当第一MDCP PDU为第一应用层报文中的最后一个MDCP PDU时，接收北斗网络设备200返回的第一应用层回执信息，该第一应用层回执信息用于指示北斗网络设备200解析第一应用层报文的结果。
处理单元1420，可用于生成第一应用层报文。
在出站的一种设计中，收发单元1410，可用于接收第一MDCP PDU。其中，第一MDCP PDU的包头信息包括后继指示字段。后继指示字段用于指示第一MDCP PDU在第一应用层报文中的顺序。
处理单元1420，可用于在确定出第一MDCP PDU为第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，基于第一MDCP PDU得到第一应用层报文；其中，M为正整数。
处理单元1420，可用于生成第一应用层回执信息，该第一应用层回执信息用于指示终端100解析第一应用层报文的结果。
收发单元1410，可用于向北斗网络设备200发送第一应用层回执信息。
可选的，收发单元1410，还可用于执行上述图13所示方法实施例中终端100执行的有关发送和接收的功能步骤。
可选的，处理单元1420，还可用于执行上述图13所示方法实施例中终端100执行的有关协议解析与封装以及运算确定的功能步骤。
应理解，该种设计中的通信装置1200可对应执行前述实施例中终端100执行的方法步骤，为了简洁，在此不再赘述。
在采用集成的单元的情况下，参见图15，图15是本申请实施例提供的通信装置1500的结构示意图。该通信装置1500可以为上述实施例中的北斗网络设备200。可选的，通信装置1500可以为北斗网络设备200中的具体网元，例如，北斗地面收发站22、北斗中心站23、北斗短报文融合通信平台24中的一个网元或多个网元的组合。如图15所示，该通信装置1500可以包括收发单元1510和处理单元1520。
在入站的一种设计中，收发单元1510，可用于接收第一MDCP PDU。其中，第一MDCP  PDU的包头信息包括后继指示字段。后继指示字段用于指示第一MDCP PDU在第一应用层报文中的顺序。
处理单元1520，可用于在确定出第一MDCP PDU为第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，基于第一MDCP PDU得到第一应用层报文；其中，M为正整数。
处理单元1520，可用于生成第一应用层回执信息，该第一应用层回执信息用于指示北斗网络设备200解析第一应用层报文的结果。
收发单元1510，可用于向终端100发送第一应用层回执信息。
在出站的一种设计中，收发单元1510，可用于向终端100发送第一应用层报文中的第一MDCP PDU。其中，第一MDCP PDU的包头信息包括后继指示字段。后继指示字段用于指示第一MDCP PDU在第一应用层报文中的顺序。
收发单元1510，可用于当第一MDCP PDU为第一应用层报文中的最后一个MDCP PDU时，接收终端100返回的第一应用层回执信息，该第一应用层回执信息用于指示终端100解析第一应用层报文的结果。
处理单元1520，可用于生成第一应用层报文。
可选的，收发单元1510，还可用于执行上述图13所示方法实施例中北斗网络设备200执行的有关发送和接收的功能步骤。
可选的，处理单元1520，还可用于执行上述图像13所示方法实施例中北斗网络设备200执行的有关协议解析与封装以及运算确定的功能步骤。
应理解，该种设计中的通信装置1500可对应执行前述实施例中北斗网络设备200执行的方法步骤，为了简洁，在此不再赘述。
以上介绍了本申请实施例的终端100和北斗网络设备200，应理解，但凡具备上述图14所述的终端100的功能的任何形态的产品，但凡具备上述图15所述的北斗网络设备200的功能的任何形态的产品，都落入本申请实施例的保护范围。
作为一种可能的产品形态，本申请实施例所述的终端100，可以由一般性的总线体系结构来实现。
参见图16，图16是本申请实施例提供的通信装置1600的结构示意图。该通信装置1600可以是终端100，或其中的装置。如图16所示，该通信装置1600包括处理器1601和与所述处理器内部连接通信的收发器1602。其中，处理器1601是通用处理器或者专用处理器等。例如可以是卫星通信的基带处理器或中央处理器。卫星通信的基带处理器可以用于对卫星通信协议以及卫星通信数据进行处理，中央处理器可以用于对通信装置(如，基带芯片，终端、终端芯片等)进行控制，执行计算机程序，处理计算机程序的数据。收发器1602可以称为收发单元、收发机、或收发电路等，用于实现收发功能。收发器1602可以包括接收器和发送器，接收器可以称为接收机或接收电路等，用于实现接收功能；发送器可以称为发送机或发送电路等，用于实现发送功能。可选的，通信装置1600还可以包括天线1603和/或射频单元(图未示意)。所述天线1603和/或射频单元可以位于所述通信装置1600内部，也可以与所述通信装置1600分离，即所述天线1603和/或射频单元可以是拉远或分布式部署的。
可选的，通信装置1600中可以包括一个或多个存储器1604，其上可以存有指令，该指 令可为计算机程序，所述计算机程序可在通信装置1600上被运行，使得通信装置1600执行上述方法实施例中描述的方法。可选的，所述存储器1604中还可以存储有数据。通信装置1600和存储器1604可以单独设置，也可以集成在一起。
其中，处理器1601、收发器1602、以及存储器1604可以通过通信总线连接。
一种设计中，通信装置1600可以用于执行前述实施例中终端100的功能：处理器1601可以用于执行上述图13所示实施例中终端100执行的有关协议解析与封装以及运算确定的功能步骤和/或用于本文所描述的技术的其它过程；收发器1602可以用于执行上述图13所示实施例中终端100执行的有关发送和接收的功能步骤和/或用于本文所描述的技术的其它过程。
在上述任一种设计中，处理器1601中可以包括用于实现接收和发送功能的收发器。例如该收发器可以是收发电路，或者是接口，或者是接口电路。用于实现接收和发送功能的收发电路、接口或接口电路可以是分开的，也可以集成在一起。上述收发电路、接口或接口电路可以用于代码/数据的读写，或者，上述收发电路、接口或接口电路可以用于信号的传输或传递。
在上述任一种设计中，处理器1601可以存有指令，该指令可为计算机程序，计算机程序在处理器1601上运行，可使得通信装置1600执行上述方法实施例中终端100执行的方法步骤。计算机程序可能固化在处理器1600中，该种情况下，处理器1601可能由硬件实现。
在一种实现方式中，通信装置1600可以包括电路，所述电路可以实现前述方法实施例中发送或接收或者通信的功能。本申请中描述的处理器和收发器可实现在集成电路(integrated circuit，IC)、模拟IC、射频集成电路RFIC、混合信号IC、专用集成电路(application specific integrated circuit，ASIC)、印刷电路板(printed circuit board，PCB)、电子设备等上。该处理器和收发器也可以用各种IC工艺技术来制造，例如互补金属氧化物半导体(complementary metal oxide semiconductor，CMOS)、N型金属氧化物半导体(nMetal-oxide-semiconductor，NMOS)、P型金属氧化物半导体(positive channel metal oxide semiconductor，PMOS)、双极结型晶体管(bipolar junction transistor，BJT)、双极CMOS(BiCMOS)、硅锗(SiGe)、砷化镓(GaAs)等。
本申请中描述的通信装置的范围并不限于此，而且通信装置的结构可以不受图16的限制。通信装置1600可以是独立的设备或者可以是较大设备的一部分。例如所述通信装置1600可以是：
(1)独立的集成电路IC，或芯片，或，芯片系统或子系统；
(2)具有一个或多个IC的集合，可选的，该IC集合也可以包括用于存储数据，计算机程序的存储部件；
(3)ASIC，例如调制解调器(Modem)；
(4)可嵌入在其他设备内的模块；
(5)接收机、终端、智能终端、蜂窝电话、无线设备、手持机、移动单元、车载设备、网络设备、云设备、人工智能设备等等；
(6)其他等等。
作为一种可能的产品形态，本申请实施例所述的北斗网络设备200中的任一网元(例如、北斗地面收发站22、北斗中心站23、北斗短报文融合通信平台24)，可以由一般性的总线体系结构来实现。
参见图17，图17是本申请实施例提供的通信装置1700的结构示意图。该通信装置1700 可以是北斗网络设备200，或其中的装置。如图17所示，该通信装置1700包括处理器1701和与所述处理器内部连接通信的收发器1702。其中，处理器1701是通用处理器或者专用处理器等。例如可以是卫星通信的基带处理器或中央处理器。卫星通信的基带处理器可以用于对卫星通信协议以及卫星通信数据进行处理，中央处理器可以用于对通信装置(如，基带芯片等)进行控制，执行计算机程序，处理计算机程序的数据。收发器1702可以称为收发单元、收发机、或收发电路等，用于实现收发功能。收发器1702可以包括接收器和发送器，接收器可以称为接收机或接收电路等，用于实现接收功能；发送器可以称为发送机或发送电路等，用于实现发送功能。可选的，通信装置1700还可以包括天线1703和/或射频单元(图未示意)。所述天线1703和/或射频单元可以位于所述通信装置1700内部，也可以与所述通信装置1700分离，即所述天线1703和/或射频单元可以是拉远或分布式部署的。
可选的，通信装置1700中可以包括一个或多个存储器1704，其上可以存有指令，该指令可为计算机程序，所述计算机程序可在通信装置1700上被运行，使得通信装置1700执行上述方法实施例中描述的方法。可选的，所述存储器1704中还可以存储有数据。通信装置1700和存储器1704可以单独设置，也可以集成在一起。
其中，处理器1701、收发器1702、以及存储器1704可以通过通信总线连接。
一种设计中，通信装置1700可以用于执行前述实施例中北斗网络设备200的功能：处理器1701可以用于执行上述图13所示实施例中北斗网络设备200执行的有关协议解析与封装以及运算确定的功能步骤和/或用于本文所描述的技术的其它过程；收发器1702可以用于执行上述图13所示实施例中北斗网络设备200执行的有关发送和接收的功能步骤和/或用于本文所描述的技术的其它过程。
在上述任一种设计中，处理器1701中可以包括用于实现接收和发送功能的收发器。例如该收发器可以是收发电路，或者是接口，或者是接口电路。用于实现接收和发送功能的收发电路、接口或接口电路可以是分开的，也可以集成在一起。上述收发电路、接口或接口电路可以用于代码/数据的读写，或者，上述收发电路、接口或接口电路可以用于信号的传输或传递。
在上述任一种设计中，处理器1701可以存有指令，该指令可为计算机程序，计算机程序在处理器1701上运行，可使得通信装置1700执行上述方法实施例中北斗网络设备200执行的方法步骤。计算机程序可能固化在处理器1701中，该种情况下，处理器1701可能由硬件实现。
本申请实施例还提供一种计算机可读存储介质，该计算机可读存储介质中存储有计算机程序代码，当上述处理器执行该计算机程序代码时，使得通信装置执行前述任一实施例中的方法。
本申请实施例还提供一种计算机程序产品，当该计算机程序产品在计算机上运行时，使得计算机执行前述任一实施例中的方法。
本申请实施例还提供一种通信装置，该装置可以以芯片的产品形态存在，该装置的结构中包括处理器和接口电路，该处理器用于通过接收电路与其它装置通信，使得该装置执行前述任一实施例中的方法。
本申请实施例还提供一种北斗通信系统，包括终端100和北斗网络设备200，该终端100和北斗网络设备200可以执行前述任一实施例中的方法。
本申请全文介绍了北斗通信系统中短报文的通信功能，可以理解的是，其他卫星系统中 也可能存在支持短报文的通信功能。因此，不限制在北斗通信系统中，若有其他卫星系统也支持短报文的通信功能，本申请中介绍的方法，也同样适用于其他卫星系统的通信。
结合本申请公开内容所描述的方法或者算法的步骤可以硬件的方式来实现，也可以是由处理器执行软件指令的方式来实现。软件指令可以由相应的软件模块组成，软件模块可以被存放于随机存取存储器(Random Access Memory，RAM)、闪存、可擦除可编程只读存储器(Erasable Programmable ROM，EPROM)、电可擦可编程只读存储器(Electrically EPROM，EEPROM)、寄存器、硬盘、移动硬盘、只读光盘(CD-ROM)或者本领域熟知的任何其它形式的存储介质中。一种示例性的存储介质耦合至处理器，从而使处理器能够从该存储介质读取信息，且可向该存储介质写入信息。当然，存储介质也可以是处理器的组成部分。处理器和存储介质可以位于ASIC中。另外，该ASIC可以位于核心网接口设备中。当然，处理器和存储介质也可以作为分立组件存在于核心网接口设备中。
本领域技术人员应该可以意识到，在上述一个或多个示例中，本申请所描述的功能可以用硬件、软件、固件或它们的任意组合来实现。当使用软件实现时，可以将这些功能存储在计算机可读介质中或者作为计算机可读介质上的一个或多个指令或代码进行传输。计算机可读介质包括计算机可读存储介质和通信介质，其中通信介质包括便于从一个地方向另一个地方传送计算机程序的任何介质。存储介质可以是通用或专用计算机能够存取的任何可用介质。
以上所述，以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (34)

  1. 一种北斗通信系统中应用层回执传输方法，其特征在于，包括：
    终端发送第一应用层报文中的第一消息数据汇聚层协议数据单元MDCP PDU给北斗网络设备；其中，所述第一MDCP PDU的包头信息包括后继指示字段；所述后继指示字段用于指示所述第一MDCP PDU在所述第一应用层报文中的顺序；
    当所述第一MDCP PDU为所述第一应用层报文中的最后一个MDCP PDU时，所述终端接收到所述北斗网络设备发送的第一应用层回执信息；其中，所述第一应用层回执信息用于指示所述北斗网络设备解析所述第一应用层报文的结果。
  2. 根据权利要求1所述的方法，其特征在于，所述终端发送第一应用层报文中的第一MDCP PDU给北斗网络设备，具体包括：
    所述终端将所述第一MDCP PDU作为所述终端的SLC层的第一卫星链路控制层服务数据单元SLC SDU，从所述终端的MDCP层下发至所述终端的SLC层；
    所述终端在所述终端的SLC层将所述第一SLC SDU拆分成N个卫星链路控制层协议数据单元SLC PDU，N为正整数；其中，所述N个SLC PDU包括第一SLC PDU，所述第一SLC PDU的帧头信息包括帧总数字段和帧序号字段；所述帧总数字段用于指示所述第一SLC SDU中包括的SLC PDU的总数量N，所述帧序号字段用于指示所述第一SLC PDU在所述第一SLC SDU中的帧序号；
    所述终端将所述N个SLC PDU发送给所述北斗网络设备。
  3. 根据权利要求2所述的方法，其特征在于，所述第一应用层回执信息还用于指示所述北斗网络设备已收齐所述第一SLC SDU中的N个SLC PDU。
  4. 根据权利要求2所述的方法，其特征在于，所述终端接收到所述北斗网络设备发送的第一应用层回执信息之前，所述方法还包括：
    所述终端接收到所述北斗网络设备发送的第一确认字符ACK；其中，所述第一ACK用于指示所述北斗网络设备已收齐所述第一SLC SDU中的N个SLC PDU。
  5. 根据权利要求3所述的方法，其特征在于，所述终端接收到所述北斗网络设备发送的第一应用层回执信息之前，所述方法还包括：
    所述终端接收到所述北斗网络设备发送的第二确认字符ACK；其中，所述第二ACK用于指示所述第一SLC SDU中所述北斗网络设备未接收到的SLC PDU的帧序号；
    所述终端重传所述第一SLC SDU中所述北斗网络设备未接收到的SLC PDU给所述北斗网络设备。
  6. 根据权利要求4所述的方法，其特征在于，在所述终端接收到所述北斗网络设备发送的第一确认字符ACK之前，所述方法还包括：
    所述终端接收到所述北斗网络设备发送的第二确认字符ACK；其中，所述第二ACK用于指示所述第一SLC SDU中所述北斗网络设备未接收到的SLC PDU的帧序号；
    所述终端重传所述第一SLC SDU中所述北斗网络设备未接收到的SLC PDU给所述北斗 网络设备。
  7. 根据权利要求2-6中任一项所述的方法，其特征在于，所述终端将所述N个SLC PDU发送给所述北斗网络设备，具体包括：
    所述终端将所第一SLC PDU从所述终端的SLC层下发至物理PHY层，作为所述终端的PHY层的第一用户帧；
    所述终端针对所述第一用户帧进行物理层处理得到第一入站数据；
    所述终端将所述第一入站数据发送给所述北斗网络设备。
  8. 根据权利要求1-7中任一项所述的方法，其特征在于，所述终端发送第一应用层报文中的第一MDCP PDU给北斗网络设备之前，所述方法还包括：
    所述终端在消息数据汇聚MDCP层获取到所述终端的应用层下发的第一应用层报文；
    所述终端在所述MDCP层将所述第一应用层报文作为MDCP SDU，并在所述MDCP SDU加入填充数据和冗余长度指示字段后，拆分成M个MDCP PDU；其中，M为正整数；所述冗余长度指示字段用于指示所述填充数据的数据长度，所述M个MDCP PDU中包括第一MDCP PDU。
  9. 根据权利要求8所述的方法，其特征在于，所述方法还包括：
    所述终端将所述M个MDCP PDU从所述MDCP层下发至所述SLC层，作为所述SLC层的所述M个SLC SDU，所述M个SLC SDU包括第一SLC SDU。
  10. 根据权利要求8或9所述的方法，其特征在于，在所述终端在MDCP层获取到终端的应用层下发的第一应用层报文之前，所述方法还包括：
    所述终端获取原始数据；
    所述终端在所述应用层将所述原始数据，进行编码压缩得到第一压缩数据；
    所述终端在所述应用层将所述第一压缩数据进行加密得到第一加密后数据；
    所述终端在所述第一加密后数据头部加上报文头信息，得到所述第一应用层报文；其中，所述报文头信息包括压缩指示字段和加密指示字段，所述压缩指示字段用于指示对所述原始数据压缩时使用的编码压缩算法，所述加密指示字段用于指示对所述第一压缩数据加密时使用的加密算法。
  11. 根据权利要求1-10中任一项所述的方法，其特征在于，所述终端接收到所述北斗网络设备发送的第一应用层回执信息之后，所述方法还包括：
    所述终端基于所述第一应用层回执信息确定所述北斗网络设备解析所述第一应用层报文失败，所述终端向所述北斗网络设备重传所述第一应用层报文。
  12. 根据权利要求10所述的方法，其特征在于，所述第一应用层回执信息包括第一解析结果，其中，所述第一解析结果用于指示所述北斗网络设备解密第一应用层报文失败；所述终端接收到所述北斗网络设备发送的第一应用层回执信息之后，所述方法还包括：
    所述终端与所述北斗网络设备协商密钥信息；
    所述终端基于协商后的密钥信息加密所述第一压缩数据得到第二加密后数据；
    所述终端将包括有所述第二加密后数据的第二应用层报文发送到所述北斗网络设备。
  13. 根据权利要求10或12任一项所述的方法，其特征在于，所述第一应用层回执信息包括第二解析结果，其中，所述第二解析结果用于指示所述北斗网络设备解码解压缩应用层报文失败；所述终端接收到所述北斗网络设备发送的第一应用层回执信息之后，所述方法还包括：
    所述终端基于所述第二解析结果和所述北斗网络设备协商码本；
    所述终端基于协商后的码本编码压缩所述原始数据得到第二压缩数据；
    所述终端将所述第二压缩数据加密，得到第三加密后数据；
    所述终端将第三应用层报文发送给所述北斗网络设备，所述第三应用层报文包括所述第三加密后数据。
  14. 一种北斗通信系统中应用层回执传输方法，其特征在于，包括：
    北斗网络设备接收到终端发送的第一应用层报文的第一MDCP PDU；其中，所述第一MDCP PDU的包头信息包括后继指示字段；所述后继指示字段用于指示所述第一MDCP PDU在所述第一应用层报文中的顺序；
    在所述北斗网络设备确定出所述第一MDCP PDU为所述第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，所述北斗网络设备基于所述第一MDCP PDU得到所述第一应用层报文；其中，M为正整数；
    所述北斗网络设备生成第一应用层回执信息，所述第一应用层回执信息用于指示所述北斗网络设备解析所述第一应用层报文的结果；
    所述北斗网络设备将所述第一应用层回执信息发送至所述终端。
  15. 根据权利要求14所述的方法，其特征在于，在所述北斗网络设备生成第一应用层回执信息之前，所述方法还包括：
    所述北斗网络设备对所述第一应用层报文中的第一加密后数据进行解密，并在解密成功后得到第一压缩数据。
  16. 根据权利要求15所述的方法，其特征在于，在所述北斗网络设备对所述第一应用层报文中的第一加密后数据进行解密，并在解密成功后得到第一压缩数据之后，所述方法还包括：
    所述北斗网络设备对所述第一压缩数据进行解码解压缩得到原始数据。
  17. 根据权利要求14所述的方法，其特征在于，在所述北斗网络设备生成第一应用层回执信息之前，所述方法还包括：
    所述北斗网络设备对所述第一加密后数据解密失败；
    所述北斗网络设备生成第一应用层回执信息；其中，所述第一应用层回执信息包括第一解析结果，所述第一解析结果用于指示所述北斗网络设备解密失败。
  18. 根据权利要求15所述的方法，其特征在于，在所述北斗网络设备生成第一应用层回执信息之前，所述方法还包括：
    所述北斗网络设备对所述第一压缩数据解码解压缩失败；
    所述北斗网络设备生成第一应用层回执信息；其中，所述第一应用层回执信息包括第二解析结果，所述第二解析结果用于指示所述北斗网络设备解码失败。
  19. 根据权利要求16所述的方法，其特征在于，所述第一应用层回执信息包括第三解析结果，所述第三解析结果用于指示所述北斗网络设备解析所述应用层报文成功。
  20. 根据权利要求16或19所述的方法，其特征在于，所述方法还包括：
    所述北斗网络设备将所述原始数据通过蜂窝网络发送给蜂窝用户设备。
  21. 根据权利要求13-20任一项所述的方法，其特征在于，所述北斗网络设备接收到终端发送的第一应用层报文的第一MDCP PDU之前，所述方法还包括：
    所述北斗网络设备在PHY层获取到所述终端发送的第一入站数据；
    所述北斗网络设备基于所述第一入站数据执行物理层处理得到第一用户帧；
    所述北斗网络设备将所述第一用户帧作为所述北斗网络设备的SLC层中的第一SLC PDU，从所述PHY层呈递给所述北斗网络设备的SLC层。
  22. 根据权利要求21所述的方法，其特征在于，在所述北斗网络设备将所述第一用户帧作为所述北斗网络设备的SLC层中的第一SLC PDU，从所述PHY层呈递给所述北斗网络设备的SLC层之后，所述方法还包括：
    所述北斗网络设备接收到所述终端发送的第一SLC SDU中的X个SLC PDU，X为正整数；其中，所述X个SLC PDU包括第一SLC PDU，所述第一SLC PDU的帧头信息包括帧总数字段和帧序号字段；所述帧总数字段用于指示所述第一SLC SDU中包括SLC PDU的总数量N，N为正整数，所述帧序号字段用于指示所述第一SLC PDU在所述第一SLC SDU中的帧序号；
    当所述X小于所述N时，所述北斗网络设备向所述终端发送第二ACK，其中，所述第二ACK用于指示所述第一SLC SDU中所述北斗网络设备未接收到的SLC PDU的帧序号。
  23. 根据权利要求22所述的方法，其特征在于，当所述北斗网络设备接收到所述终端发送的第一SLC SDU中的X个SLC PDU后，所述方法还包括：
    当所述X等于所述N时，所述北斗网络设备在SLC层将所述X个SLC PDU拼接成所述第一SLC SDU，并将所述第一SLC SDU作为MDCP层的第一MDCP PDU从所述北斗网络设备的SLC层上报给北斗网络设备的MDCP层。
  24. 根据权利要求22或23所述的方法，其特征在于，当所述北斗网络设备接收到所述终端发送的第一SLC SDU中的X个SLC PDU后，所述方法还包括：
    当所述X等于所述N时，所述北斗网络设备向所述终端发送第一ACK，其中，所述第一ACK用于指示所述北斗网络设备已收齐所述第一SLC SDU中的N个SLC PDU。
  25. 根据权利要求14-24任一项所述的方法，其特征在于，在所述北斗网络设备确定出所述第一MDCP PDU为所述应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后， 所述北斗网络设备基于所述第一MDCP PDU得到所述应用层报文，具体包括：
    所述北斗网络设备在所述MDCP层将所述M个MDCP PDU拼接得到MDCP SDU，并将所述MDCP SDU作为应用层报文从所述MDCP层上报给应用层。
  26. 根据权利要求14-25任一项所述的方法，其特征在于，所述北斗网络设备将所述第一应用层回执信息发送至所述终端，具体包括：
    所述北斗网络设备将所述第一应用层回执信息从所述北斗网络设备的应用层经过预设接口发送至所述北斗网络设备的SLC层；
    所述北斗网络设备在所述SLC层给所述第一应用层回执信息添加帧头信息后，将添加了所述帧头信息的所述第一应用层回执信息下发至物理层，得到回执帧；其中，帧头信息包括帧类型字段，所述帧类型字段用于指示用户帧的帧类型；
    所述北斗网络设备将所述回执帧发送至所述终端。
  27. 一种北斗通信系统，其特征在于，包括：终端和北斗网络设备；其中：
    所述终端，用于向所述北斗网络设备发送第一应用层报文的第一MDCP PDU；
    所述北斗网络设备，用于接收所述第一MDCP PDU；
    所述北斗网络设备，还用于在确定出所述第一MDCP PDU为所述第一应用层报文中的M个MDCP PDU中的最后一个MDCP PDU之后，基于所述第一MDCP PDU得到所述第一应用层报文；其中，M为正整数；
    所述北斗网络设备，还用于生成第一应用层回执信息，所述第一应用层回执信息用于指示所述北斗网络设备解析所述第一应用层报文的结果；
    所述北斗网络设备，还用于向所述终端发送所述第一应用层回执信息；
    所述终端，用于接收所述第一应用层回执信息。
  28. 一种通信装置，其特征在于，包括一个或多个处理器、一个或多个存储器和收发器；其中，所述收发器、所述一个或多个存储器与所述一个或多个处理器耦合，所述一个或多个存储器用于存储计算机程序代码，所述计算机程序代码包括计算机指令，当一个或多个处理器在执行所述计算机指令时，使得所述通信装置执行如权利要求1-13任一项所述的方法。
  29. 根据权利要求28所述的通信装置，其特征在于，所述通信装置为终端。
  30. 一种通信装置，其特征在于，包括一个或多个处理器、一个或多个存储器、收发器；其中，所述收发器、所述一个或多个存储器与所述一个或多个处理器耦合，所述一个或多个存储器用于存储计算机程序代码，所述计算机程序代码包括计算机指令，当一个或多个处理器在执行所述计算机指令时，使得所述通信装置执行如权利要求14-26任一项所述的方法。
  31. 根据权利要求30所述的通信装置，其特征在于，所述通信装置为北斗网络设备。
  32. 一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当所述指令在计算机上运行时，使得所述计算机执行如权利要求1-13任一项所述的方法。
  33. 一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当所述指令在计算机上运行时，使得所述计算机执行如权利要求14-26任一项所述的方法。
  34. 一种芯片或芯片系统，应用于终端，其特征在于，包括处理电路和接口电路，所述接口电路用于接收代码指令并传输至所述处理电路，所述处理电路用于运行所述代码指令以执行如权利要求1-13任一项所述的方法。
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