WO2023011379A1 - 一种北斗通信系统中入站传输控制方法、系统及相关装置 - Google Patents

一种北斗通信系统中入站传输控制方法、系统及相关装置 Download PDF

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Publication number
WO2023011379A1
WO2023011379A1 PCT/CN2022/109288 CN2022109288W WO2023011379A1 WO 2023011379 A1 WO2023011379 A1 WO 2023011379A1 CN 2022109288 W CN2022109288 W CN 2022109288W WO 2023011379 A1 WO2023011379 A1 WO 2023011379A1
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Prior art keywords
slc
terminal
sdu
network device
pdu
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PCT/CN2022/109288
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English (en)
French (fr)
Inventor
朱旭东
钱锋
甘雯昱
姚振东
王宝
姚楚婷
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华为技术有限公司
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Priority to EP22852092.0A priority Critical patent/EP4355024A1/en
Publication of WO2023011379A1 publication Critical patent/WO2023011379A1/zh

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    • 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
    • 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
    • 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
    • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
    • H04L1/1867—Arrangements specially adapted for the transmitter end
    • 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
    • H04L69/06—Notations for structuring of protocol data, e.g. abstract syntax notation one [ASN.1]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/12—Messaging; Mailboxes; Announcements
    • H04W4/14—Short messaging services, e.g. short message services [SMS] or unstructured supplementary service data [USSD]

Definitions

  • the present application relates to the field of satellite communications, in particular to a method, system and related devices for inbound transmission control 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 is different from other global positioning and navigation systems such as the global positioning system (GPS) and the global navigation satellite system (GLONASS). It is used for positioning and communication in areas where mobile communication is not covered, or cannot be covered, or the communication system is destroyed, such as oceans, deserts, grasslands, and uninhabited areas.
  • the communication system of the Beidou short message service upgrades the technical system, and opens some necessary resources of the communication system of the Beidou short message service to civilian use. According to the characteristics of the civil service and equipment, it needs to be based on the characteristics of the communication system of the Beidou short message service Design communication protocols.
  • the communication system of the Beidou short message service communicates through satellite links, its main characteristics are: 1. Time extension; 2. High link loss; 3. The supported services are mainly burst short message services; 4. Does not support link state management, mobility management, broadcast control information, etc.
  • the current wireless communication protocol cannot be applied to the communication system of the Beidou short message service, because: due to the long distance of satellite communication, the communication system of the Beidou short message service requires high terminal transmission power. Due to the limitations of the radio frequency devices of current civilian terminals (such as mobile phones and other terminals), the terminal cannot continuously send signals to Beidou short message satellites for a long time.
  • the radio frequency device of the terminal In order not to damage the radio frequency device on the terminal as much as possible, after the radio frequency device of the terminal continues to work in the sending state for a period of time, it must be turned off and stopped for a period of time before continuing to switch to the sending state.
  • the signaling interaction process in the existing wireless communication protocol is implemented in the Beidou short message service, which takes too long.
  • the air interface resources in the communication system of the Beidou short message service are limited and cannot meet the signaling interaction. Therefore, , there is no interactive protocol flow specifically designed to control signaling.
  • there is no broadcast information in the communication of the Beidou short message service and the terminal cannot obtain the configuration information of the Beidou network equipment through the broadcast information. Therefore, when the data packet sent by the terminal is lost, the terminal cannot notify the Beidou network equipment to negotiate the retransmission of the data packet through special control signaling or broadcast information, and cannot guarantee the normal progress of the data transmission process.
  • the present application provides an inbound transmission control method, system and related devices in the Beidou communication system, which realizes the normal progress of the data transmission process when the data packet of the terminal is lost in the Beidou communication system.
  • the present application provides an inbound transmission control method in the Beidou communication system, including: the terminal sends N satellite link control layer protocol data units SLC PDUs in the first satellite link control layer service data unit SLC SDU
  • N is a positive integer; among them, N SLC PDUs include the first SLC PDU, and the frame header information of the first SLC PDU includes the service data unit alternate indication SAI field, the total number of frames field and the frame sequence number field; the SAI field is used In order to indicate whether the first SLC PDU is retransmission data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate the frame sequence number of the first SLC PDU in the first SLC SDU ;
  • the terminal When the terminal receives the first confirmation character ACK sent by the Beidou network equipment, the terminal retransmits the SLC PDU not received by the Beidou network equipment in the first SLC SDU to the Beidou network equipment, wherein the first ACK is used to indicate the first SLC SDU The frame number of the SLC PDU not received by the Beidou network equipment.
  • the terminal can split the application layer message into multiple MDCP PDUs at the MDCP layer.
  • the terminal can sequentially deliver MDCP PDUs to the SLC layer as SLC SDUs of the SLC layer, and split the SLC SDUs into N SLC PDUs at the SLC layer.
  • the frame header information includes an SAI field, a frame total number field and a frame sequence number field.
  • 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 this 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 can send the N SLC PDUs of the first SLC PDU to the Beidou network equipment. If the Beidou network device determines that the SLC PDU in the first SLC SDU is missing based on the frame header information of the received SLC PDU, it returns the first ACK to the terminal, wherein the first ACK is used to indicate that the Beidou network device has not received the first SLC SDU The frame sequence number of the SLC PDU in an SLC SDU. After receiving the first ACK from the Beidou network device, the terminal retransmits the SLC PDUs in the first SLC SDU that have not been received by the Beidou network device to the Beidou network device.
  • the method further includes: when the terminal receives the second ACK sent by the Beidou network device, the terminal sends the first SLC SDU to the Beidou network device.
  • the terminal receives the second ACK sent by the Beidou network device, the terminal sends the first SLC SDU to the Beidou network device.
  • One or more SLC PDUs in the second SLC SDU are sent to the Beidou network equipment, and the second ACK is used to indicate that the Beidou network equipment has received N SLC PDUs in the first SLC SDU.
  • the terminal sends all the SLC PDUs in the next SLC SDU to the Beidou network equipment to keep the continuous transmission of data.
  • the value of the SAI field of the SLC PDU in the first SLC SDU is different from the value of the SAI field of the SLC PDU in the second SLC SDU.
  • the value of the SAI field of the SLC PDU is flipped or not to indicate whether the SLC PDU is retransmission data, which can ensure that the Beidou network equipment can identify whether the received SLC PDU is retransmission data, and ensure that the data in the Beidou communication system Continuous transmission.
  • the method further includes: when the terminal sends the N SLC PDUs in the first SLC SDU to the Beidou network In the subsequent ACK reception time window of the device, if the ACK sent by the Beidou network device is not received, the terminal retransmits the N SLC PDUs in the first SLC SDU to the Beidou network device.
  • the method before the terminal sends N SLC PDUs in the first SLC SDU to the Beidou network device, the method further includes: the terminal obtains at the SLC layer multiple SLC SDUs delivered by the MDCP layer of the terminal , wherein the multiple SLC SDUs include the first SLC SDU and the second SLC SDU; the terminal splits the first SLC SDU into N SLC PDUs at the SLC layer.
  • the method before the terminal obtains at the SLC layer multiple SLC SDUs issued by the MDCP layer of the terminal, the method further includes: the terminal obtains at the MDCP layer the application layer report issued by the application layer of the terminal The terminal uses the application layer message as the MDCP SDU at the MDCP layer, and splits the MDCP SDU into multiple MDCP PDUs after adding padding data and redundant length indication fields; where the redundant length indication field is used to indicate padding data
  • the data length of the plurality of MDCP PDUs includes the first MDCP PDU, and the header information of the first MDCP PDU includes a subsequent indication field, and the subsequent indication field is used to indicate the order of the first MDCP PDU in the plurality of MDCP PDUs;
  • the terminal sends multiple MDCP PDUs from the MDCP layer to the SLC layer as multiple SLC SDUs of the SLC layer.
  • the method before the terminal obtains the application layer message sent by the application layer of the terminal at the MDCP layer, the method further includes: the terminal obtains the original data; the terminal compresses the original data at the application layer to obtain Compress data; the terminal encrypts the compressed data at the application layer to obtain encrypted data; the terminal adds message header information to the encrypted data header to obtain an application layer message; wherein, the message header information includes a compression indication field and an encryption indication field, the compression indication field is used to indicate the compression algorithm used when compressing the original data, and the encryption indication field is used to indicate the encryption algorithm used when the compressed data is encrypted.
  • the terminal sends N SLC PDUs in the first SLC SDU to the Beidou network device, which specifically includes: the terminal sends the first SLC PDU from the SLC layer to the physical PHY layer as the first SLC PDU of the PHY layer.
  • a coded block the terminal adds check bit information at the end of the first coded block at the PHY layer, and encodes the first coded block and the check bit information to obtain the first coded data; the terminal adds the first coded data at the PHY layer Insert the pilot information to obtain the first pilot data; the terminal modulates the first pilot data and the synchronization header of the first pilot data at the PHY layer to obtain the first modulation data and the first modulation synchronization header; the terminal performs the modulation at the PHY layer Spreading the first modulated data and the modulated synchronization header to obtain the first spread-spectrum modulated data; the terminal sends the first spread-spectrum modulated data to the Beidou network equipment at the PHY layer.
  • the terminal is based on the moment when the terminal sends the last SLC PDU in the first SLC SDU, the switching time of the terminal from the sending state to the receiving state, the air interface propagation delay, and the signal processing scheduling time of the Beidou network equipment Delay, determine the starting moment of the ACK receiving time window;
  • the terminal starts to receive the ACK sent by the Beidou network equipment at the beginning of the ACK receiving time window.
  • the formula for the terminal to determine the starting time of the ACK receiving time window is:
  • tUeStartRcvAck is the starting moment of the ACK receiving time window
  • tUeTxEnd is the moment when the terminal sends the last SLC PDU in the first SLC SDU
  • tTx2RxSwitch is the switching time of the terminal from the sending state to the receiving state
  • tPropagate is the air interface propagation delay
  • tStationProcess is the signal processing scheduling delay on Beidou network equipment.
  • the terminal is based on the time length of the physical frame sent by the terminal, the air interface propagation delay, the signal processing scheduling delay of the Beidou network device, the time length of the physical frame sent by the Beidou network device, and the time length of the physical frame sent by the Beidou network device.
  • the time alignment deviation of the physical frame determines the end time of the ACK reception time window; the terminal stops receiving the ACK sent by the Beidou network equipment at the end time of the ACK reception time window.
  • the formula for the terminal to determine the end time of the ACK receiving time window is:
  • tUeEndRcvAck tUeTxEnd+tUeUlFrameLen+2*tPropagate+tStationProcess+tStationDlFrameLen+ ⁇
  • tUeEndRcvAck is the end time of the ACK receiving time window
  • tUeUlFrameLen is the time length of the physical frame sent by the terminal
  • tPropagate is the air interface propagation delay
  • tStationProcess is the signal processing scheduling delay of the Beidou network equipment
  • tStationDlFrameLen is the physical frame sent by the Beidou network equipment
  • ⁇ is the time alignment deviation of the physical frame sent by the Beidou network equipment.
  • the present application provides another inbound transmission control method in the Beidou communication system, including: the Beidou network equipment receives M SLC PDUs in the first SLC SDU sent by the terminal, and M is a positive integer; wherein, M Each SLC PDU includes the first SLC PDU, and the frame header information of the first SLC PDU includes the SAI field, the frame total number field and the frame sequence number field; the SAI field is used to indicate whether the SLC PDU is retransmission data, and the frame total number field is used to indicate the first
  • the SLC SDU includes the total number N of SLC PDUs, N is a positive integer, and the frame number field is used to indicate the frame number of the first SLC PDU in the first SLC SDU;
  • the Beidou network device sends the first ACK to the terminal, wherein the first ACK is used to indicate the frame sequence number of the SLC PDU not received by the Beidou network device in the first SLC SDU.
  • the Beidou network device after the Beidou network device receives M SLC PDUs in the first SLC SDU sent by the terminal, when M is equal to N, the Beidou network device sends a second ACK to the terminal, wherein the second ACK It is used to indicate that the Beidou network equipment has received N SLC PDUs in the first SLC SDU; the Beidou network equipment has received one or more SLC PDUs in the second SLC SDU sent by the terminal.
  • the terminal sends all the SLC PDUs in the next SLC SDU to the Beidou network equipment to keep the continuous transmission of data.
  • the value of the SAI field of the SLC PDU in the second SLC SDU is different from the value of the SAI field of the SLC PDU in the first SLC SDU.
  • the value of the SAI field of the SLC PDU is flipped or not to indicate whether the SLC PDU is retransmission data, which can ensure that the Beidou network equipment can identify whether the received SLC PDU is retransmission data, and ensure that the data in the Beidou communication system Continuous transmission.
  • the Beidou network device receives M SLC PDUs in the first SLC SDU sent by the terminal, specifically including: the Beidou network device obtains the first spread spectrum modulation data sent by the terminal at the PHY layer; The network device despreads the first spread spectrum modulated data at the PHY layer to obtain the first modulated data and the first modulated synchronization header; the Beidou network device demodulates the first modulated data and the first modulated synchronization header at the PHY layer to obtain The first pilot data and the first synchronization header; the Beidou network equipment removes the pilot information in the first pilot data at the PHY layer to obtain the first encoded data; the Beidou network equipment decodes the first encoded data at the PHY layer to obtain The first coded block and the first verification information; the Beidou network device verifies the first coded block based on the first verification information at the PHY layer, and after the verification is successful, uses the first coded block as the SLC of the Beidou network device The first SLC PDU
  • the method further includes: the Beidou network device splicing the M SLC PDUs into the first SLC at the SLC layer SDU, and report the first SLC SDU as the first MDCP PDU of the MDCP layer from the SLC layer of the Beidou network device to the MDCP layer of the Beidou network device.
  • the header information of the first MDCP PDU includes a successor indication field, which is used for Indicates the order of the first MDCP PDU among multiple MDCP PDUs sent by the terminal.
  • the method also includes: the Beidou network device obtains at the MDCP layer the second MDCP PDU reported from the SLC layer of the Beidou network device;
  • the Beidou network device When the successor indication field in the second MDCP PDU indicates that the second MDCP PDU is the last of multiple MDCP PDUs sent by the terminal, the Beidou network device will splice the first MDCP PDU and the second MDCP PDU into an MDCP SDU at the MDCP layer, And report the MDCP SDU as an application layer message from the MDCP layer to the application layer.
  • the application layer message includes message header information and encrypted data
  • the message header information includes an encryption indication field and a compression indication field
  • the compression indication field is used to instruct the terminal to compress the original data into compressed data
  • the compression algorithm used when the encryption indication field is used to indicate the encryption algorithm used when the terminal encrypts the compressed data into encrypted data
  • the method also includes: the Beidou network device decrypts the encrypted data in the application layer message through the encryption algorithm indicated by the encryption indication field in the application layer message at the application layer to obtain compressed data;
  • the compression algorithm indicated by the compression indication field in the message decompresses the compressed data to obtain the original data.
  • the Beidou network device receives the frame sequence number of the first SLC PDU in the first SLC SDU, the total number of SLC PDUs in the first SLC SDU, the receiving time of the first SLC PDU, and the number sent by the terminal.
  • the frame interval of the physical frame and the time length of the physical frame sent by the terminal determine the remaining time length of the SLC PDU receiving window.
  • the Beidou network equipment determines the remaining time length of the SLC PDU receiving window through the following formula:
  • tStationRevWindow tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen)
  • tStationRevWindow is the remaining time length of the SLC PDU receiving window
  • tStatRevRctSP is the receiving moment of the first SLC PDU
  • nUeTotalFrameNum is the total number of SLC PDUs in the first SLC SDU
  • nRevFrameSN is the frame number of the first SLC PDU
  • tUeTxInterval is the terminal sending The frame interval of the physical frame.
  • tUeUlFrameLen is the time length of the physical frame sent by the terminal.
  • the method further includes: the Beidou network device determines the time point for sending the ACK based on the remaining time length of the SLC PDU receiving window and the signal processing scheduling delay of the Beidou network device.
  • the Beidou network equipment determines the time point of sending ACK through the following formula:
  • tStationSendAck is the time point when Beidou network equipment sends ACK
  • tStationRevWindow is the remaining time length of the SLC PDU receiving window
  • tStationProcess is the signal processing scheduling delay on Beidou network equipment
  • ⁇ is the sending time of outbound physical frames on Beidou network equipment Alignment deviation.
  • the present application provides a Beidou communication system, including: terminals and Beidou network equipment; wherein,
  • the terminal is used to send N SLC PDUs in the first SLC SDU to the Beidou network equipment, and N is a positive integer; wherein, the frame header information of the SLC PDU includes the SAI field, the total number of frames field and the frame sequence number field; the SAI field Used to indicate whether the SLC PDU is retransmission data, the total number of frames field is used to indicate the total number N of SLC PDUs included in the first SLC SDU, and the frame sequence number field is used to indicate that the SLC PDU is in the first SLC SDU serial number; the Beidou network device is used to receive M SLC PDUs in the first SLC SDU sent by the terminal, and M is a positive integer; the Beidou network device is also used to send the The terminal sends the first ACK, wherein the first ACK is used to indicate the frame sequence number of the SLC PDU that the Beidou network device has not received in the first SLC SDU; the terminal is also used when receiving the Beidou network device. During
  • the terminal may also execute the method in any possible implementation manner of the foregoing first aspect.
  • the Beidou network device may also execute the method in any possible implementation manner of the foregoing first aspect.
  • 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 foregoing first aspect.
  • 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 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 above.
  • FIG. 1A is a schematic structural diagram of a Beidou communication system provided by an embodiment of the present application.
  • FIG. 1B is a schematic diagram of a Beidou communication protocol layer provided by the embodiment of the present application.
  • FIG. 2 is a schematic diagram of a data inbound transmission process in a Beidou communication system provided by an embodiment of the present application
  • FIG. 3 is a schematic structural diagram of a terminal provided in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a protocol encapsulation architecture of inbound data of a Beidou communication system provided by an embodiment of the present application
  • FIG. 5 is a schematic diagram of a protocol analysis framework for inbound data of a Beidou communication system provided by an embodiment of the present application
  • FIG. 6 is a schematic diagram of a protocol processing flow for data at the MDCP layer and the SLC layer of a Beidou communication system provided by an embodiment of the present application;
  • FIG. 7 is a schematic diagram of a reception confirmation mechanism of the SLC layer when data is inbound provided by an embodiment of the present application.
  • Fig. 8 is a schematic diagram of the processing flow when the SLC PDU sent by the terminal provided by the embodiment of the present application is lost;
  • FIG. 9 is a schematic diagram of the processing flow when the ACK returned by the Beidou network equipment provided by the embodiment of the present application is lost;
  • Figure 10 is a schematic diagram of the processing flow when the SLC PDU and ACK are lost at the same time when the data is inbound provided by the embodiment of the present application;
  • FIG. 11 is a schematic flowchart of an inbound transmission control method in the Beidou communication system provided by an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a communication device provided by an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of another communication device provided by an embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of another 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.
  • 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.
  • FIG. 1A shows a schematic structural diagram of a Beidou communication system 10 provided in an embodiment of the present application.
  • the Beidou communication system 10 may include a terminal 100 , a Beidou short message satellite 21 , a Beidou network device 200 , a short message center 25 and a terminal 300 .
  • the Beidou communication system 10 may also include an emergency rescue platform 26 and an emergency rescue center 27 .
  • the terminal 100 can send the short message information to the Beidou short message satellite 21, and the Beidou short message satellite 21 only relays and directly forwards 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 content of the general message type parsed from the short message information to the short message 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 can also send the emergency distress message sent by the terminal 100 to the emergency rescue center 27 through the emergency rescue platform 26.
  • the terminal 300 can also send the short message to the short message center 25 through a traditional cellular communication network.
  • the short message center 25 can forward the short message of the terminal 300 to the Beidou network device 200 .
  • the Beidou network device 200 can relay the short message of the terminal 300 to the terminal 100 through the Beidou short message satellite 21 .
  • the above-mentioned Beidou network equipment 200 may include a Beidou ground transceiver station 22 , a Beidou central station 23 and a Beidou short message integrated communication platform 24 .
  • the Beidou ground transceiver station 22 may include one or more devices with a sending function and one or more devices with a receiving function, or may include one or more devices with a sending function and a receiving function, which is not limited herein .
  • the Beidou communication protocol layer may include an application (application layer protocol, APP) layer, a message data convergence (message data convergence protocol, MDCP) layer, a satellite link control layer (satellite link control protocol, SLC) layer and Physical (physical layer protocol, PHY) layer.
  • APP application layer protocol
  • MDCP message data convergence protocol
  • SLC satellite link control protocol
  • PHY Physical (physical layer protocol, PHY) layer.
  • the Beidou ground transceiver station 22 can be used for the data processing function of the Beidou network equipment 200 at the PHY layer.
  • the Beidou central station 23 can be used for the Beidou network device 200 to process data at the SLC layer and the MDCP layer.
  • the Beidou short message fusion communication platform 24 can be used to process data at the APP layer.
  • the Beidou communication system 10 since the Beidou communication system 10 communicates through satellite links, its main characteristics are: time extension (about 270 ms in one direction) and large link loss.
  • the services currently supported by the Beidou communication system 10 are mainly burst short message services, and do not support link state management, mobility management, and broadcast control information.
  • the terminal 100 can actively send data to the Beidou network device 200 through the Beidou short message satellite 21 .
  • the central station on the ground cannot actively page users. Due to the long propagation distance of satellite communication, the Beidou communication system 10 requires high transmission power of the terminal 100 . Due to the limitation of the radio frequency device on the current terminal 100, the terminal 100 cannot continuously send signals to the Beidou short message satellite 21 for a long time. In order not to damage the radio frequency device on the terminal 100 as much as possible, after the radio frequency device of the terminal 100 has been working for a period of time in the sending state, it must stop working for a period of time before continuing to switch to the sending state to continue working.
  • the duration of the sending state on the terminal 100 is determined by the underlying hardware capability of the terminal 100 .
  • the terminal 100 in order to ensure that the data received by the terminal 100 and the data sent do not interfere with each other, the terminal 100 does not support sending data and receiving data simultaneously. The terminal 100 needs to wait to receive the data sent by the Beidou network device 200 after sending the data.
  • the working mode of the Beidou network device 200 may be a duplex mode, which can send and receive data at the same time, and the Beidou network device 200 can send and receive data for a long time.
  • Fig. 2 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 acknowledgment character (acknowledge character, 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 user equipment before the user equipment sends data, it can interact with the receiving device to control signaling to pre-allocate the sending physical resources of the user equipment.
  • the interaction time of the control signaling is too long, and the resources of the air interface on the Beidou communication 10 are limited. Therefore, no special control signaling is designed in the Beidou communication system 10 to allocate physical resources when the terminal 100 sends data.
  • there is no dedicated broadcast channel in the Beidou communication system 10 to transmit broadcast information and the terminal 100 cannot obtain the configuration information of the Beidou network device 200 through the broadcast information.
  • the terminal 100 sends data to the Beidou network device 200 and there is a packet loss, there is no guarantee that the Beidou network device 200 can recover the complete data.
  • the embodiment of the present application provides an inbound transmission control method in the Beidou communication system, and the terminal 100 can split the application layer message into multiple MDCP PDUs at the MDCP layer.
  • the terminal 100 can sequentially deliver MDCP PDUs to the SLC layer as SLC SDUs of the SLC layer, and split the SLC SDUs into N SLC PDUs at the SLC layer.
  • 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 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 this 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 may send the N SLC PDUs of the first SLC PDU to the Beidou network device 200.
  • the Beidou network device 200 determines that the SLC PDU in the first SLC SDU is missing based on the frame header information of the received SLC PDU, then return the first ACK to the terminal 100, wherein the first ACK is used to indicate that the Beidou network device 200 is not The frame sequence number of the SLC PDU in the first SLC SDU received. After receiving the first ACK from the Beidou network device 200, the terminal 100 retransmits the SLC PDUs in the first SLC SDU that the Beidou network device 200 has not received to the Beidou network device 200.
  • the Beidou network device 200 determines that the N SLC PDUs in the first SLC SDU have been received based on the frame header information of the received SLC PDU, then return the second ACK to the terminal 100, wherein the second ACK is used to indicate Beidou The network device 200 has received N SLC PDUs in the first SLC SDU. After receiving the second ACK, the terminal 100 can send all the SLC PDUs in the second SLC SDU to the Beidou network device 200.
  • FIG. 3 shows a schematic structural diagram of the terminal 100 .
  • the terminal 100 shown in FIG. 3 is only an example, and the terminal 100 may have more or fewer components than those shown in FIG. 3, may combine two or more components, or may have Different component configurations.
  • the various components shown in Figure 3 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 and the like 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 may 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 of 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 may implement an audio function 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 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 may 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 protocol encapsulation framework for inbound data of the Beidou communication system 10 provided in the embodiment of the present application is introduced below.
  • FIG. 4 shows a schematic diagram of a protocol encapsulation 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 terminal 100 can be divided into application layer (application layer protocol), message data convergence layer (message data convergence protocol, MDCP), satellite link control layer (satellite link control protocol) , SLC) and physical layer (physical layer protocol, PHY).
  • application layer application layer protocol
  • message data convergence layer messages data convergence protocol
  • MDCP message data convergence protocol
  • satellite link control layer satellite link control protocol
  • PHY physical layer protocol
  • the workflow of the Beidou message transmission protocol on the terminal 100 can be as follows:
  • the terminal 100 can compress the original data into compressed data through a compression algorithm, and add a compression indication field in front of the compressed data, wherein the compression indication field can be used to indicate the compression algorithm type of the compressed data. Afterwards, the terminal 100 may encrypt the compressed data to obtain encrypted data, and add an encryption indication field to the header of the encrypted data, where the encryption indication field is used to indicate the encryption algorithm type of the encrypted data. The terminal 100 may encapsulate the encrypted data, the compressed indication field, and the encrypted indication field into an application layer message and send it to the MDCP layer.
  • the application layer message includes a message header and message data.
  • the message header includes a compression indication field, an encryption indication field, and the like.
  • the message data includes the above-mentioned encrypted data.
  • the terminal 100 may also encrypt the compression indication field and the compressed data together 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 an MDCP SDU. Due to the limitation of the air interface, the terminal 100 can only send a physical frame of a specified length at the physical layer each time, so that the length of the MDCP layer data is restricted to the specified length. Therefore, at the MDCP layer, the terminal 100 can add padding to a specified length at the end of the MDC SDU, and add a redundant length indication field at the head of 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, get MDCP PDU, that is, MDCP PDU includes M_segment and successor indication field.
  • MDCP PDU that is, MDCP PDU includes M_segment and successor indication field.
  • the follow-up indicator field can be used to indicate that the current MDCP PDU is the initial MDCP PDU, intermediate MDCP PDU or the last MDCP PDU among multiple MDCP PDUs sent continuously; or, it is an MDCP PDU sent separately.
  • the terminal 100 can obtain the MDCPPDU sent by the MDCP layer through the interlayer interface as the SLC SDU.
  • the terminal 100 can segment the SLC SDU into one or more (up to 4) 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 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, as a code block (code block) of the PHY layer, and add a synchronization header at the head of the code block, and add a calibration at the end of the code block. Parity field.
  • a cyclic redundancy check (cyclic redundancy check, CRC) may be used to check the code block, therefore, the check digit field may include a CRC code.
  • the terminal 100 can encode the code block and the parity field (for example, polar encoding) to obtain coded data (coded data), and then insert a pilot into the coded data to obtain pilot coded data (pilot+data).
  • the terminal 100 sequentially modulates the synchronization header and the coded pilot data through the underlying hardware to obtain modulated data (modulated data).
  • modulated data modulated data
  • the terminal 100 may spread the modulated data to obtain spread modulated data (spread+modulated data).
  • the terminal 100 can send the spread-spectrum modulated data to the Beidou short message satellite 21, and then forward it to the Beidou network device 200 via the Beidou short message satellite 21.
  • a protocol analysis framework for inbound data of the Beidou communication system 10 provided in the embodiment of the present application is introduced below.
  • FIG. 5 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 short message transmission protocol layer of Beidou network device 200 can be divided into APP layer, MDCP layer, SLC layer and PHY layer.
  • the Beidou network device 200 may include a Beidou ground transceiver station 22 , a Beidou central station 23 and a 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 short message transmission protocol layer of the Beidou network device 200 can be as follows:
  • the Beidou network device 200 can obtain the modulated and spread-spectrum coded pilot data sent by the terminal 100 .
  • the Beidou network device 200 may despread the received spread spectrum modulated data (spread+modulated data) to obtain modulated data (modulated data). Then, the Beidou network device 200 can demodulate the modulated data to obtain pilot coded data (pilot+data). Next, the Beidou network device 200 removes the pilot information in the pilot coded data to obtain coded data (codedata). Then, the Beidou network device 200 can decode the coded data, and verify the integrity of the code block (codeblock) through the check data in the check bit field. If it is complete, the Beidou network device 200 can extract the code block (codeblock), and present it to the SLC layer through the interlayer interface as the SLC PDU of the SLC layer.
  • 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.
  • Beidou network device 200 can splice all MDCP PDUs belonging to the same MDCP SDU into one MDCP SDU.
  • the Beidou network device 200 can present the MDCP SDU to the APP layer through the interlayer interface as an application layer message received by the APP layer.
  • the Beidou network device 200 can decrypt and decompress the application layer message based on the message header of the application layer message to obtain the original data.
  • the protocol processing flow of the Beidou communication system 10 for data at the MDCP layer and the SLC layer is specifically introduced below.
  • FIG. 6 shows a schematic diagram of the protocol processing flow of the Beidou communication system 10 at the MDCP layer and the SLC layer provided in the embodiment of the present application.
  • 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 field to the header of each MDCP segment data to obtain an MDCP PDU, that is, an MDCP PDU includes M_segment and a follow-up indication field.
  • the terminal 100 can store the MDCP PDU obtained by splitting into the MDCP layer transmission buffer (MDCP Txbuffer) according to the order of reception:
  • 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 padding data and the MDCP SDU after adding the redundant length indication field into three MDCP PDUs, wherein, according to the order of high bits to low bits, the three MDCP PDUs
  • the PDUs are MDCP PDU0, MDCP PDU1 and MDCP PDU2 in turn.
  • 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 terminal 100 may split the padding data and the MDCP SDU after adding the redundant length indication field into two MDCP PDUs, wherein, according to the order of high bits to low bits, these two The MDCP PDUs are MDCP PDU0 and MDCP PDU1 in turn.
  • 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 the last MDCP PDU in the current MDCP SDU
  • terminal 100 may set the value of the successor indication field in MDCP PDU1 to "11".
  • the terminal 100 may use the padding data and the MDCP SDU after adding the redundancy length indication field as one MDCP PDU0. Wherein, since MDCP PDU0 is the only MDCP PDU in the current MDCP SDU, the terminal 100 can set the value of the successor indication field in MDCP PDU0 to "00".
  • the terminal 100 at the SLC layer can send the state controller through the SLC layer, and control the SLC PDU sending strategy of the SLC layer based on the receiving feedback (for example, ACK) sent by the Beidou network device 200, including the initial transmission and re-transmission of the SLC PDU pass.
  • the terminal 100 can obtain the MDCPPDU delivered by the MDCP layer through the interlayer interface as the SLC SDU.
  • the terminal 100 sends the previous SLC SDU to the Beidou network device 200 and confirms that the Beidou network device 200 has successfully received it, it will obtain the next MDCP PDU from the MDCP layer as the next SLC SDU and send it to the Beidou network device 200.
  • the terminal 100 may split the padding data and the MDCP SDU after adding the redundancy length indication field into three MDCP PDUs.
  • the three MDCP PDUs are MDCP PDU0, MDCP PDU1 and MDCP PDU2.
  • the terminal 100 first obtains the MDCP PDU0 issued by the MDCP layer through the interlayer interface, and the terminal 100 can send the MDCP PDU0 as the first SLC SDU of the SLC layer in this message transmission process to the Beidou network device 200.
  • the terminal 100 After the terminal 100 determines that the Beidou network device 200 has sent the data of the first SLC SDU to the Beidou network device 200, the terminal 100 can obtain the MDCP PDU1 from the MDCP layer, and use the MDCP PDU1 as the second SLC in the message transmission process The SDU is sent to the Beidou network device 200. After the terminal 100 determines that the Beidou network device 200 has sent the data of the second SLC SDU to the Beidou network device 200, the terminal 100 can obtain the MDCP PDU2 from the MDCP layer, and use the MDCP PDU2 as the last SLC in the message transmission process The SDU is sent to the Beidou network device 200.
  • the terminal 100 may send all MDCPPDUs belonging to one MDCP SDU to the SLC layer at the MDCP layer, and store them in the sending buffer of the SLC layer as multiple SLC SDUs of the SLC layer.
  • the terminal 100 sends an SLC SDU at the SLC layer
  • the terminal 100 sends an SLC SDU to the Beidou network device 200 and confirms that the Beidou network device 200 has successfully received it, it continues to obtain and send the next SLC from the sending buffer of the SLC layer SLC SDUs.
  • the terminal 100 can segment the SLC SDU into one or more fixed-length SLC segment data (S_segment), and add frame header information to the head of each S_segment 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 terminal 100 can determine whether the SLC PDU to be sent currently belongs to an unsent SLC SDU, and if so, the terminal 100 can set the value of the SAI field in the SLC PDU to be the same as that of 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 terminal 100 can set the value of the SAI field in the SLC PDU to be the same as the value of the SAI field of the SLC PDU in the previous SLC SDU session.
  • 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 may all be "0"
  • the values of the SAI fields of the 4 SLC PDUs in the second SLC SDU may all be "1"
  • the values of the SAI fields of the 4 SLC PDUs in the 3rd SLC SDU may all be "0".
  • 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.
  • S_segment fixed-length SLC segment data
  • the value of the total number of frames field of the only SLC PDU in the SLC SDU can be "00".
  • the value of the total number of frames field of the 2 SLC PDUs in the SLC SDU can be "01".
  • the SLC SDU includes 3 SLC PDUs the value of the total number of frames field of the 3 SLC PDUs in the SLC SDU can be "10".
  • the SLC SDU includes 4 SLC PDUs the value of the total number of frames field of the 4 SLC PDUs in the SLC SDU can be "11".
  • 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.
  • S_segment fixed-length SLC segment data
  • the value of the frame sequence number field of the only SLC PDU in the SLC SDU may be "00".
  • the value of the frame sequence number field in the first SLC PDU in the SLC SDU can be "00"
  • the value of the frame sequence number field in the second SLC PDU in the SLC SDU can be "01".
  • the value of the frame sequence number field in the first SLC PDU in the SLC SDU can be "00"
  • the value of the frame sequence number field in the second SLC PDU in the SLC SDU can be "01”
  • the value of the frame sequence number field in the third SLC PDU in the SLC SDU can be "10”.
  • the value of the frame sequence number field in the first SLC PDU in the SLC SDU can be "00"
  • the value of the frame sequence number field in the second SLC PDU in the SLC SDU can be "01”
  • the value of the frame sequence number field in the third SLC PDU in the SLC SDU can be "10”
  • the value of the frame sequence number field in the fourth SLC PDU in the SLC SDU can be "11".
  • the frame header information of the SLC PDU may also include an acknowledgment mode enable (AMenable) field, and the acknowledgment mode enable field may be used to indicate whether the terminal 100 uses an acknowledgment mode (AM) to send the SLC PDU. If the terminal 100 uses the confirmation mode to send the SLC PDU, the Beidou network device 200 can send feedback information to the terminal 100 at the SLC layer after receiving one or more SLC PDUs sent by the terminal 100. The feedback information is used to notify the terminal 100 of the SLC PDUs not received by the Beidou network device 200.
  • Aenable acknowledgment mode enable
  • AM acknowledgment mode enable field
  • the Beidou network device 200 After the Beidou network device 200 receives the SLC PDU of the terminal 100, it can judge whether all the SLC PDUs in an SLC SDU have been received based on the frame header information of the SLC PDU. If so, the Beidou network device 200 can pass the received One or more SLC PDUs are sequentially spliced into one SLC SDU according to the value of the frame sequence number field from small to large. If all the SLC PDUs in one SLC SDU have not been received, the Beidou network device 200 can send feedback information (for example, ACK) to the terminal 100 after the SLC layer receiving window ends. The feedback information is used to notify the terminal 100 of the SLC PDUs not received by the Beidou network device 200. After splicing the SLC SDUs, the Beidou network device 200 can report the SLC SDUs to the MDCP layer through the interlayer interface as MDCP PDUs.
  • feedback information for example, ACK
  • the Beidou network device 200 at the SLC layer 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 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 terminal 100.
  • the SAI value of the first SLC PDU in the first SLC SDU received by the Beidou network device 200 may be "0", the total number of frames is “11", and the frame number is “00".
  • the SAI value of the second SLC PDU in the first SLC SDU can be "0", the total number of frames is "11", and the frame number is "01”.
  • the SAI value of the third SLC PDU in the first SLC SDU can be "0", the total number of frames is "11", and the frame number is "10”.
  • the SAI value of the fourth SLC PDU in the first SLC SDU can be "0", the total number of frames is "11", and the frame number is "11".
  • the Beidou network device 200 can splice the four SLC PDUs into the first SLC SDU according to the order of the frame sequence numbers from small to large, and report it to the MDCP layer as MDCP PDU0 of the MDCP layer.
  • the Beidou network device 200 can store the MDCP PDU0 in the MDCP layer receiving buffer (MDCP Rxbuffer). Among them, the value of the successor indication field in MDCP PDU0 is "01".
  • the SAI value of the first SLC PDU in the second SLC SDU received by the Beidou network device 200 may be "1", the total number of frames is “11", and the frame number is “00".
  • the SAI value of the second SLC PDU in the second SLC SDU can be "1", the total number of frames is "11", and the frame number is "01”.
  • the SAI value of the third SLC PDU in the second SLC SDU can be "1", the total number of frames is "11", and the frame number is "10”.
  • the SAI value of the fourth SLC PDU in the second SLC SDU can be "1", the total number of frames is "11", and the frame number is "11".
  • the Beidou network device 200 can splice the four SLC PDUs into the second SLC SDU according to the order of the frame numbers from small to large, and report it to the MDCP layer as MDCP PDU1 of the MDCP layer.
  • the Beidou network device 200 can store the MDCP PDU1 in the MDCP layer receiving buffer (MDCP Rxbuffer). Among them, the value of the successor indication field in MDCP PDU1 is "10".
  • the SAI value of the first SLC PDU in the third SLC SDU received by the Beidou network device 200 may be "0", the total number of frames is "11", and the frame number is "00".
  • the SAI value of the second SLC PDU in the third SLC SDU can be "0", the total number of frames is "11", and the frame number is "01”.
  • the SAI value of the third SLC PDU in the third SLC SDU can be "0", the total number of frames is "11", and the frame number is "10”.
  • the SAI value of the fourth SLC PDU in the third SLC SDU can be "0", the total number of frames is "11", and the frame number is "11".
  • the Beidou network device 200 can splicing these 4 SLC PDUs into the third SLC SDU according to the frame sequence number from small to large, and report it to the MDCP layer as MDCP PDU2 of the MDCP layer.
  • the Beidou network device 200 can store the MDCP PDU2 in the MDCP layer receiving buffer (MDCP Rxbuffer). Among them, the value of the successor indication field in MDCP PDU2 is "11".
  • the Beidou network device 200 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 Beidou network device 200 can take out all the MDCP PDUs from the MDCP Rxbuffer, and follow the order of the value of the subsequent indication field and the receiving time Perform splicing, and remove redundant indication fields and padding data after splicing to obtain MDCP SDUs.
  • the Beidou network device 200 can report the MDCP SDU to the application layer through the interlayer interface as an application layer message.
  • the following describes the reception confirmation mechanism of the SLC layer in the Beidou communication system 10 provided in the embodiment of the present application when data is inbound.
  • FIG. 7 shows a reception confirmation mechanism of the SLC layer when data is inbound provided in the embodiment of the present application.
  • the communication interaction process of Beidou communication system 10 at the SLC layer can be as follows:
  • the terminal 100 can send N SLC PDUs among the SLC SDUs at equal intervals in the order of frame numbers from small to large.
  • N ⁇ M M is the maximum number of segments of SLC SDU.
  • the M value is taken as 4 for illustration.
  • Beidou network device 200 After receiving the first SLC PDU, Beidou network device 200 starts the SLC layer receiving session (session) at time t0, calculates the remaining time length of the SLC PDU receiving window (tStationRevwindow), and feeds back ACK after the SLC PDU receiving window ends Give the terminal 100.
  • the data part of the ACK occupies N bits, which is used to represent the frame sequence number of the SLC PDU that the Beidou network device 200 has received.
  • the i-th bit of the data part of the ACK can be used to indicate whether the Beidou network device 200 has received the i-th SLC PDU in the SLC SDU, where i ⁇ N.
  • the terminal 100 switches the radio frequency hardware from the sending (Tx) state to the receiving (Rx) state, and receives the ACK fed back by the Beidou network device 200 within the ACK receiving window.
  • tStationProcess refers to the signal processing scheduling delay on the Beidou network device 200 . Among them, since tStationProcess is dynamic, it is necessary to ensure that the maximum delay is fixed. According to the experimental data, the minimum value of tStationProcess (t_MinStatProc) can be 1s, and the maximum value of tStationProcess (t_MaxStatProc) can be 4s.
  • tPropagate refers to the air interface propagation delay between the terminal 100 and the Beidou network device 200 .
  • the typical value of tPropagate may be 270 ms as measured by experimental data.
  • tUeRevAckWindow refers to the duration window length for the terminal 100 to receive the ACK.
  • tUeStartRcvAck refers to the start time when the terminal 100 receives the ACK.
  • tUeEndRcvAck refers to the stop time when the terminal 100 receives the ACK.
  • tTx2RxSwitch refers to the switching time of the terminal 100 from the sending state to the receiving state.
  • the typical value of tTx2RxSwitch may be 600 ms as measured by experimental data.
  • ⁇ refers to the sending time alignment deviation of the outbound physical frame on the Beidou network device 200 .
  • the Beidou network device 200 completes signal processing and scheduling, it may not be exactly at the sending time of the outbound physical frame, and it needs to wait for the sending time of the next outbound physical frame before sending the physical frame. Among them, 0 ⁇ 125ms.
  • tUeUlFrameLen refers to the time length of the SLC PDU sent by the terminal 100. Among them, 128ms ⁇ tUeUlFrameLen ⁇ 512ms.
  • nUeTotalFrameNum refers to the total number of frames of the SLC SDU segmented by the terminal 100, that is, the total number of frames including the SLC PDU in one SLC SDU.
  • tUeTxInterval refers to the time interval for the terminal 100 to send the SLC PDU.
  • the transmission interval (tUeTxInterval) of the SLC PDU can refer to the time interval between the transmission end time of the previous SLC PDU and the transmission start time of the next SLC PDU among two adjacent SLC PDUs.
  • tUeTxInterval is a preset value, wherein, exemplary, a typical value of tUeTxInterval may be 2s.
  • tStationRevWindow refers to the remaining time length of the SLC PDU receiving time window on the Beidou network device 200, referred to as the remaining time length of the SLC PDU receiving window.
  • tStationSendAck refers to the time when the Beidou network device 200 sends an ACK to the terminal 100 .
  • nStationRevFrameSN refers to the frame number of the SLC PDU currently received by the Beidou network device 200. Wherein, since in the embodiment of the present application, the SLC SDU can include at most 4 frames of the SLC PDU, therefore, 0 ⁇ nStationRevFrameSN ⁇ 3, and nStationRevFrameSN is an integer.
  • tUeTxEnd refers to the moment when the terminal 100 sends the last SLC PDU in the SLC SDU, as a reference point for receiving the ACK time.
  • tStationDlFrameLen refers to the time length of the physical frame sent by the Beidou network device 200 .
  • the value of tStationDlFrameLen in the embodiment of the present application is a fixed value, for example, the value of tStationDlFrameLen may be 125ms.
  • the Beidou network device 200 determines the remaining time length of the SLC PDU receiving window in the embodiment of the present application, and how the terminal 100 determines the start time of the ACK receiving window and the end time of the ACK window.
  • the Beidou network device 200 can receive the latest SLC PDU based on the frame sequence number, the total number of SLC PDU frames in the current SLC SDU session, and the receiving time when the Beidou network device 200 receives the latest SLC PDU.
  • the time interval of the SLC PDU sent by the terminal 100 and the time length of the physical frame sent by the terminal 100 determine the remaining time length of the SLC PDU receiving window on the Beidou network device 200.
  • the Beidou network device 200 can determine the remaining time length of the SLC PDU receiving window through the following formula (1):
  • tStationRevWindow tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen) formula (1)
  • tStationRevWindow is the remaining time length of the SLC PDU receiving window on the Beidou network device 200.
  • nUeTotalFrameNum is the total number of SLC PDU frames in the current SLC SDU session.
  • nRevFrameSN is the frame sequence number of the latest SLC PDU received by Beidou network equipment 200.
  • tStatRevRctSP is the receiving moment when the Beidou network device 200 receives the latest SLC PDU.
  • tUeTxInterval is the time interval for the terminal 100 to send the SLC PDU.
  • tUeUlFrameLen is the time length of the physical frame sent by the terminal 100 .
  • tUeTxInterval The value of tUeTxInterval is preset on the terminal 100 and the Beidou network device 200 .
  • nRevFrameSN ⁇ 0, 1, . . . , nUeTotalFrameNum-1 ⁇ .
  • Beidou network device 200 can determine the time point for sending ACK based on the receiving moment of the latest SLC PDU, the remaining time length of the SLC PDU receiving window, and the signal processing scheduling delay of Beidou network device 200.
  • the Beidou network device 200 can determine the time point of sending the ACK through the following formula (2):
  • tStationSendAck is the time point when the Beidou network device 200 sends the ACK.
  • tStationRevWindow is the remaining time length of the SLC PDU receiving window on the Beidou network device 200.
  • tStationProcess is the signal processing scheduling delay on the Beidou network device 200 .
  • ⁇ is the sending time alignment deviation of the outbound physical frame on the Beidou network device 200 .
  • tStationAckLen is the time length of the ACK sent by the Beidou network device 200 . The value of tStationAckLen can be 125ms.
  • the terminal 100 can be based on the moment when the terminal 100 finishes sending the last SLC PDU in the SLC SDU, the switching time of the terminal 100 from the sending (Tx) state to the receiving (Rx) state, the air interface propagation delay, and the signal on the Beidou network device 200
  • the scheduling delay is processed to determine the starting moment when the terminal 100 receives the ACK.
  • the terminal 100 can determine the starting time of receiving the ACK through the following formula (3):
  • tUeStartRcvAck is the start time when the terminal 100 receives the ACK.
  • tUeTxEnd is the moment when the terminal 100 finishes sending the last SLC PDU in the SLC SDU.
  • tTx2RxSwitch is the switching duration of the terminal 100 from the sending state to the receiving state.
  • tPropagate is the air interface propagation delay between the terminal 100 and the Beidou network device 200 .
  • tStationProcess is the signal processing scheduling delay on the Beidou network device 200, and tStationProcess may take the minimum value t_MinStatProc (for example, 1 second).
  • the terminal 100 can be based on the time length of the physical frame sent by the terminal 100, the air interface propagation delay between the terminal 100 and the Beidou network device 200, the signal processing scheduling delay, the time length of the physical frame sent by the Beidou network device 200 and the Beidou network device
  • the sending time alignment deviation of the outbound physical frame on 200 determines the end time when the terminal 100 receives the ACK.
  • the terminal 100 can determine the end time of returning ACK through the following formula (4):
  • tUeEndRcvAck is the end time when the terminal 100 receives the ACK.
  • tUeUlFrameLen is the time length of the SLC PDU sent by the terminal 100.
  • tPropagate is the air interface propagation delay between the terminal 100 and the Beidou network device 200 .
  • tStationProcess is the signal processing scheduling delay on the Beidou network device 200, and tStationProcess may take a maximum value of t_MaxStatProc (for example, 4 seconds).
  • tStationDlFrameLen is the time length of the physical frame sent by Beidou network equipment, and the value of tStationDlFrameLen can be 125ms.
  • ⁇ is the sending time alignment deviation of the outbound physical frame on the Beidou network device 200, and in the formula (4), the value of ⁇ is 125ms.
  • FIG. 8 shows the processing flow when the SLC PDU sent by the terminal 100 is lost in the embodiment of the present application.
  • the processing flow when packet loss occurs in the SLC PDU can be as follows:
  • the terminal 100 can send N SLC PDUs in the SLC SDU at equal intervals in the order of frame sequence numbers from small to large.
  • N is the maximum segment number of SLC SDU.
  • M value is taken as 4 for illustration.
  • the xth SLC PDU is lost during transmission, 0 ⁇ x ⁇ N-1.
  • the Beidou network device 200 can determine the remaining time length of the SLC PDU receiving window (tStatRevwindow) based on the above formula (1).
  • the Beidou network device 200 can determine the time point for returning ACK to the terminal 100 through the above formula (2).
  • the Beidou network device 200 can send ACK-1 to the terminal 100 at the time point when returning ACK to the terminal 100.
  • the ACK-1 may be used to indicate that the Beidou network device 200 has not received the No. x SLC PDU.
  • the terminal 100 may determine the start time and end time of the ACK receiving window based on the above formula (3) and formula (4).
  • the terminal 100 can receive the ACK-1 sent by the Beidou network device 200 within the ACK receiving window.
  • the terminal 100 can determine that the Beidou network device 200 has not received the xth SLC PDU.
  • the terminal 100 can switch the receiving state to the sending state after the ACK receiving window ends, start the SLC SDU retransmission session (session), and retransmit the xth SLC PDU.
  • the SAI value of the xth SLC PDU in the SLC SDU retransmission session is the same as the SAI value of the xth SLC PDU in the SLC SDU initial transmission session, and the SAI values of all SLC PDUs in the SLC SDU initial transmission session are the same.
  • the Beidou network device 200 can determine that the SAI value in the xth SLC PDU is the same as the SAI value of the SLC PDU in the previous SLC SDU session (that is, the SLC SDU initial transmission session), Therefore, the Beidou network device 200 determines that the currently received No. x SLC PDU is a retransmission SLC PDU.
  • the Beidou network device 200 can determine the remaining time length (tStatRevwindow) of the SLC PDU receiving window through the above formula (1).
  • the Beidou network device 200 can determine the time point for returning ACK to the terminal 100 through the above formula (2).
  • the Beidou network device 200 may send ACK-2 to the terminal 100 at the time point when returning ACK to the terminal 100 .
  • the ACK-2 can be used to indicate that the Beidou network device 200 has received all the SLC PDUs in the SLC SDU.
  • the Beidou network device 200 After the Beidou network device 200 receives the x-th SLC PDU retransmitted by the terminal 100, it can combine the SLC PDU received in the SLC SDU initial transmission session with the x-th SLC PDU received in the SLC SDU retransmission session, Splicing into one SLC SDU according to the frame sequence number.
  • the Beidou network device 200 can report the spliced SLC SDUs from the SLC layer to the MDCP layer through the interlayer interface for processing at the MDCP layer.
  • the processing procedure of the MDCP layer reference may be made to the foregoing embodiment shown in FIG. 6 , which will not be repeated here.
  • the terminal 100 can use the end time of retransmitting the xth SLC PDU as the time when the last SLC PDU is sent in the SLC SDU retransmission session, through the above formula (3) and formula (4 ), determine the start time and end time of the ACK receiving window.
  • the terminal 100 can receive the ACK-2 sent by the Beidou network device 200 within the ACK receiving window. After receiving ACK-2, the terminal 100 can determine that the Beidou network device 200 has received the retransmitted No. x SLC PDU, that is, the Beidou network device 200 has received all the SLC PDUs in the current SLC SDU.
  • the terminal 100 can enter the next SLC SDU transmission session, and initially transmit all the SLC PDUs in the next SLC SDU at equal intervals in the order of frame numbers from small to large.
  • the terminal 100 can send 4 SLC PDUs to the Beidou network device 200 at equal intervals.
  • the Beidou network device 200 only received the No. 1, No. 2 and No. 3 SLC PDUs.
  • the Beidou network device 200 determines that the No. 0 SLC PDU is lost according to the total number of frames and frame numbers in the received SLC PDU. Therefore, the Beidou network device 200 can return ACK-1 at the time point of returning ACK, wherein the data part of the ACK-1 occupies 4 bits, and the value of the data part of the ACK-1 can be "0111", and the value "0111” Indicates that the Beidou network device 200 has not received the No.
  • the terminal 100 can retransmit the No. 0 SLC PDU to the Beidou network device 200 separately in the SLC SDU retransmission session.
  • the Beidou network device 200 After the Beidou network device 200 receives the retransmitted No. 0 SLC PDU, it can send ACK-2 to the terminal 100 at the time point when returning ACK to the terminal 100.
  • the data part of the ACK-2 occupies 4 bits, and the value of the data part of the ACK-2 can be "1111", and the value "1111" indicates that the Beidou network device 200 has collected the No. 0, No. 1, No. 2 and No. 3 SLCs PDUs.
  • the Beidou network device 200 can splice the received No. 0 SLC PDU and the received No. 1, No. 2, and No. 3 SLC PDUs into one SLC SDU according to the frame sequence number and report it to the MDCP layer. After receiving the ACK-2, the terminal 100 can enter the next SLC SDU sending session, and initially transmit all the SLC PDUs in the next SLC SDU.
  • N SLC PDUs in the SLC SDU not only one SLC PDU is lost, but also multiple SLC PDUs or even all N SLC PDUs may be lost.
  • the terminal 100 can send 4 SLC PDUs to the Beidou network device 200 at equal intervals.
  • the Beidou network device 200 only received the No. 1 SLC PDU and No. 3 SLC PDU.
  • Beidou network device 200 determines that No. 0 SLC PDU and No. 2 SLC PDU are lost according to the total number of frames and frame sequence numbers in the received SLC PDUs.
  • the Beidou network device 200 can return ACK-1 at the time point of returning ACK, wherein, the data part of the ACK-1 occupies 4 bits, and the value of the data part of the ACK-1 can be "0101", and the value "0101" indicates that BeiDou
  • the network device 200 has not received SLC PDU No. 0 and SLC PDU No. 2, but has received SLC PDU No. 1 and SLC PDU No. 3.
  • the terminal 100 can separately retransmit the No. 0 SLC PDU and the No. 2 SLC PDU to the Beidou network device 200 in the SLC SDU retransmission session.
  • the Beidou network device 200 receives the retransmitted No. 0 SLC PDU and No.
  • the terminal 100 can send ACK-2 to the terminal 100 at the time point of returning ACK to the terminal 100, wherein the data part of the ACK-2 Occupying 4 bits, the value of the data part of the ACK-2 can be "1111", and the value "1111" indicates that the Beidou network device 200 has received all SLC PDUs No. 0, No. 1, No. 2 and No. 3.
  • the terminal 100 can enter the next SLC SDU sending session, and initially transmit all the SLC PDUs in the next SLC SDU.
  • the terminal 100 may send 4 SLC PDUs to the Beidou network device 200 at equal intervals. Among them, the four SLC PDUs are all lost. Since the Beidou network device 200 has not received these 4 SLC PDUs and does not know whether the terminal 100 has sent the SLC PDU, therefore, the Beidou network device 200 will not return an ACK to the terminal 100. The terminal 100 does not receive the ACK from the Beidou network device 200 within the ACK receiving window, switches the receiving state to the sending state, starts the SLC SDU retransmission session, and retransmits the 4 SLC PDUs.
  • the Beidou network device 200 can return ACK-2 to the terminal 100 at the time point of ACK transmission. After receiving the ACK-2, the terminal 100 can enter the next SLC SDU sending session, and initially transmit all the SLC PDUs in the next SLC SDU.
  • the SLC PDU retransmitted by the terminal 100 may still be lost. Therefore, if the terminal 100 retransmits the No. x SLC PDU to the Beidou network device 200, it still does not receive the ACK returned by the BeiDou network device 200 to indicate that the No. x SLC PDU has been received. The terminal 100 can continue to retransmit the xth SLC PDU.
  • the terminal 100 cannot retransmit the SLC PDU in one SLC SDU without restriction.
  • the retransmission of the SLC PDU in one SLC SDU by the terminal 100 shall be limited to the maximum number of retransmissions (MaxReTxNum).
  • both the terminal 100 and the Beidou network device 200 can store the maximum number of retransmissions (MaxReTxNum).
  • Beidou network device 200 can determine the SLC SDU based on the maximum number of retransmissions (MaxReTxNum) and the time length of a single SLC SDU session after receiving multiple SLC PDUs in the SLC SDU initial transmission session, but not receiving all the SLC SDU PDUs Maximum transfer time.
  • MaxReTxNum the maximum number of retransmissions
  • Beidou network device 200 can consider that terminal 100 will not send retransmission SLC PDU to Beidou network device 200, therefore, Beidou network device 200 can discard the SLC SDU in the initial transmission session. SLC PDU, and end the SLC layer session with terminal 100. Among them, after the Beidou network device 200 ends the SLC layer session (SLC session) with the terminal 100, if the MDCP layer does not receive the last MDCP PDU in the entire application layer message transmission process, the Beidou network device 200 can discard the received PDU. received MDCP PDUs.
  • the Beidou network device 200 After the Beidou network device 200 ends the SLC layer session (SLC session) with the terminal 100, if it receives the SLC PDU sent by the terminal 100, it starts a new SLC layer session.
  • the terminal 100 may set the SAI values of all SLC PDUs in the first SLC SDU transmitted by the SLC layer to "0" during the entire transmission process of the application layer message.
  • the terminal 100 may set the SAI values of all SLC PDUs in the first SLC SDU transmitted by the SLC layer to "0" during the entire transmission process of the application layer message.
  • the second SLC SDU flip the SAI value of all SLC PDUs in the second SLC SDU to "1".
  • the 3rd SLC SDU flip the SAI value of all SLC PDUs in the 3rd SLC SDU to "0" again, and so on. Since the Beidou network device 200 is in the SLC layer session of the application layer message transmission process, it is impossible to feed back ACK to the terminal 100 without receiving the SLC PDU.
  • the SAI value of the first SLC PDU received by the Beidou network device 200 in the SLC layer session of the application layer message transmission process should not be "1". If the Beidou network device 200 receives the first SLC PDU with an SAI value of "1" in the SLC layer session of the application layer message transmission process, the Beidou network device 200 directly discards the SLC PDU.
  • FIG. 9 shows the processing flow when the ACK returned by the Beidou network device 200 is lost in the embodiment of the present application.
  • the terminal 100 can send N SLC PDUs in the SLC SDU at equal intervals in the order of frame sequence numbers from small to large.
  • N is the maximum segment number of SLC SDU.
  • M value is taken as 4 for illustration.
  • the Beidou network device 200 can determine the remaining time length of the SLC PDU receiving window (tStatRevwindow) based on the above formula (1).
  • the Beidou network device 200 can determine the time point for returning ACK to the terminal 100 through the above formula (2).
  • the Beidou network device 200 After receiving the N SLC PDUs in the SLC SDU, the Beidou network device 200 sends ACK-2 to the terminal 100 at the time when the ACK is returned to the terminal 100.
  • the Beidou network device 200 can splice the N SLC PDUs into one SLC SDU according to the frame sequence number.
  • the Beidou network device 200 can report the spliced SLC SDUs from the SLC layer to the MDCP layer through the interlayer interface for processing at the MDCP layer. Wherein, for the processing procedure of the MDCP layer, reference may be made to the foregoing embodiment shown in FIG. 6 , which will not be repeated here.
  • the terminal 100 may determine the start time and end time of the ACK receiving window based on the above formula (3) and formula (4).
  • the terminal 100 Due to the loss of ACK-2, the terminal 100 has not received any ACK sent by the Beidou network device 200 within the ACK receiving window, and the terminal 100 cannot determine whether the Beidou network device 200 has received the N SLC PDUs sent by the terminal 100. Therefore, the terminal 100 can switch the receiving state to the sending state after the ACK receiving window ends, start the SLC SDU retransmission session (session), and retransmit the N SLC PDUs.
  • the SAI value of the N SLC PDUs in the SLC SDU retransmission session is the same as the SAI value of the N SLC PDUs in the SLC SDU initial transmission session.
  • the Beidou network device 200 can analyze that the SAI values of the retransmitted N SLC PDUs are the same as the SAI values of the received N SLC PDUs. Therefore, the Beidou network device 200 can determine that the terminal 100 has not received the sent ACK-2.
  • the Beidou network device 200 can determine the remaining time length (tStatRevwindow) of the SLC PDU receiving window through the above formula (1).
  • the Beidou network device 200 can determine the time point for returning ACK to the terminal 100 through the above formula (2).
  • the Beidou network device 200 can discard the N SLC PDUs retransmitted by the terminal 100, and resend ACK-2 to the terminal 100 at the time when the ACK is returned to the terminal 100.
  • the terminal 100 can determine the start time and end time of the ACK receiving window through the above formula (3) and formula (4).
  • the terminal 100 can receive the ACK-2 sent by the Beidou network device 200 within the ACK receiving window. After receiving ACK-2, the terminal 100 can determine that the Beidou network device 200 has received the retransmitted N SLC PDUs.
  • the terminal 100 can send 4 SLC PDUs to the Beidou network device 200 at equal intervals.
  • the Beidou network device 200 has received the four SLC PDUs initially transmitted.
  • the Beidou network device 200 can splice the received four SLC PDUs into one SLC SDU according to the frame sequence number and report it to the MDCP layer.
  • the Beidou network device 200 can return ACK-2 at the time point of returning ACK, wherein, the data part of the ACK-2 occupies 4 bits, and the value of the data part of the ACK-2 can be "1111", and the value "1111” means BeiDou
  • the network device 200 has received all these 4 SLC PDUs.
  • the terminal 100 did not receive any ACK returned by the Beidou network device 200 within the ACK receiving window in the SLC SDU initial transmission session.
  • the terminal 100 can start the SLC SDU retransmission session, and retransmit the 4 SLC PDUs to the Beidou network device 200.
  • Beidou network device 200 can send ACK-2 to the terminal 100 at the time point when returning ACK to the terminal 100, and discard the retransmitted 4 SLC PDUs.
  • the terminal 100 can enter the next SLC SDU sending session, and initially transmit all the SLC PDUs in the next SLC SDU.
  • the terminal 100 retransmits N SLC PDUs in one SLC SDU to the Beidou network device 200.
  • the ACK-2 returned by the Beidou network device 200 may still be lost. Therefore, after terminal 100 retransmits N SLC PDUs in one SLC SDU to Beidou network device 200, if no ACK fed back by Beidou network device 200 is received within the ACK receiving window of the SLC SDU retransmission session, terminal 100 You can continue to open the SLC SDU retransmission session, and retransmit N SLC PDUs in this SLC SDU.
  • the terminal 100 cannot retransmit the SLC PDU in one SLC SDU without restriction.
  • the retransmission of the SLC PDU in one SLC SDU by the terminal 100 shall be limited to the maximum number of retransmissions (MaxReTxNum).
  • both the terminal 100 and the Beidou network device 200 can store the maximum number of retransmissions (MaxReTxNum).
  • the terminal 100 can determine the maximum transmission time of the SLC SDU based on the maximum number of retransmissions (MaxReTxNum) and the duration of a single SLC SDU session. At the end of the maximum transmission time of the SLC SDU, the terminal 100 no longer sends the retransmission SLC PDU to the Beidou network device 200, and may no longer initially transmit the next SLC PDU, so as to end the transmission of the application layer message in advance.
  • MaxReTxNum the maximum number of retransmissions
  • the Beidou network device 200 can determine the maximum transmission time of the SLC SDU based on the maximum number of retransmissions (MaxReTxNum) and the duration of a single SLC SDU session. If the Beidou network device 200 does not receive the last MDCP PDU of the MDCP SDU at the MDCP layer when the maximum transmission time of the SLC SDU ends, the Beidou network device 200 may discard the received MDCP PDU sent by the terminal 100.
  • MaxReTxNum maximum number of retransmissions
  • Fig. 10 shows the processing flow when the SLC PDU and ACK are lost at the same time when the data is inbound in the embodiment of the present application.
  • the terminal 100 can send N SLC PDUs in the SLC SDU at equal intervals in the order of frame sequence numbers from small to large.
  • N is the maximum segment number of SLC SDU.
  • M value is taken as 4 for illustration.
  • the xth SLC PDU is lost during transmission, 0 ⁇ x ⁇ N-1.
  • the Beidou network device 200 can determine the remaining time length of the SLC PDU receiving window (tStatRevwindow) based on the above formula (1).
  • the Beidou network device 200 can determine the time point for returning ACK to the terminal 100 through the above formula (2).
  • the Beidou network device 200 can send ACK-1 to the terminal 100 at the time point when returning ACK to the terminal 100.
  • the ACK-1 may be used to indicate that the Beidou network device 200 has not received the No. x SLC PDU.
  • the terminal 100 may determine the start time and end time of the ACK receiving window based on the above formula (3) and formula (4).
  • the terminal 100 Due to the loss of ACK-1, the terminal 100 has not received any ACK sent by the Beidou network device 200 within the ACK receiving window, and the terminal 100 cannot determine whether the Beidou network device 200 has received the N SLC PDUs sent by the terminal 100. Therefore, the terminal 100 can switch the receiving state to the sending state after the ACK receiving window ends, start the SLC SDU retransmission session (session), and retransmit the N SLC PDUs.
  • the SAI value of the N SLC PDUs in the SLC SDU retransmission session is the same as the SAI value of the N SLC PDUs in the SLC SDU initial transmission session.
  • the Beidou network device 200 can analyze that the SAI values of the retransmitted N SLC PDUs are the same as the SAI values of the received (N-n) SLC PDUs, n is the number of lost SLC PDUs in the SLC SDU. Therefore, the Beidou network device 200 can determine that the terminal 100 has not received the sent ACK-1.
  • the Beidou network device 200 can take out the n SLC PDUs lost in the initial SLC SDU transmission session from the retransmitted N SLC PDUs, and splice them with (N-n) SLC PDUs in the SLC SDU initial transmission session to form one SLC SDU .
  • the Beidou network device 200 can report the spliced SLC SDUs from the SLC layer to the MDCP layer through the interlayer interface for processing at the MDCP layer.
  • the processing procedure of the MDCP layer reference may be made to the foregoing embodiment shown in FIG. 6 , which will not be repeated here.
  • the Beidou network device 200 can determine the remaining time length (tStatRevwindow) of the SLC PDU receiving window through the above formula (1).
  • the Beidou network device 200 can determine the time point for returning ACK to the terminal 100 through the above formula (2).
  • the Beidou network device 200 can send ACK-2 to the terminal 100 at the time point when the ACK is returned to the terminal 100.
  • the ACK-2 can be used to indicate that the Beidou network device 200 has received all the SLC PDUs in the SLC SDU.
  • the terminal 100 can determine the start time and end time of the ACK receiving window through the above formula (3) and formula (4).
  • the terminal 100 can receive the ACK-2 sent by the Beidou network device 200 within the ACK receiving window. After receiving the ACK-2, the terminal 100 can determine that the Beidou network device 200 has received all the SLC PDUs in the current SLC SDU.
  • the terminal 100 After receiving ACK-2, the terminal 100 can enter the next SLC SDU transmission session, and initially transmit all the SLC PDUs in the next SLC SDU at equal intervals in the order of frame sequence numbers from small to large.
  • the terminal 100 can send 4 SLC PDUs to the Beidou network device 200 at equal intervals.
  • the Beidou network device 200 only received the No. 1, No. 2 and No. 3 SLC PDUs.
  • the Beidou network device 200 determines that the No. 0 SLC PDU is lost according to the total number of frames and frame numbers in the received SLC PDU. Therefore, the Beidou network device 200 can send ACK-1 to the terminal 100 at the time point of returning ACK, wherein the data part of the ACK-1 occupies 4 bits, and the value of the data part of the ACK-1 can be "0111", and the value "0111" indicates that the Beidou network device 200 has not received the No.
  • the terminal 100 did not receive any ACK returned by the Beidou network device 200 within the ACK receiving window in the SLC SDU initial transmission session.
  • the terminal 100 can start the SLC SDU retransmission session, and retransmit the 4 SLC PDUs to the Beidou network device 200.
  • the Beidou network device 200 After the Beidou network device 200 receives the retransmitted 4 SLC PDUs, it can send ACK-2 to the terminal 100 at the time point of returning ACK to the terminal 100.
  • the data part of the ACK-2 occupies 4 bits, and the value of the data part of the ACK-2 can be "1111", and the value "1111" indicates that the Beidou network device 200 has received all the four SLC PDUs.
  • the Beidou network device 200 can take out the No. 0 SLC PDU from the received 4 retransmitted SLC PDUs and splice the No. 1, No. 2 and No. 3 SLC PDUs received in the SLC SDU initial transmission session into one SLC SDU and report it to MDCP layer.
  • the terminal 100 After receiving the ACK-2, the terminal 100 can enter the next SLC SDU sending session, and initially transmit all the SLC PDUs in the next SLC SDU.
  • the terminal 100 initially transmits N SLC PDUs of one SLC SDU to the Beidou network device 200.
  • n1 SLC PDUs among the initially transmitted N SLC PDUs are lost, and Beidou network equipment 200 only receives (N-n1) initially transmitted SLC PDUs, among which, 1 ⁇ n1 ⁇ N.
  • the Beidou network device 200 may return an ACK to the terminal 100, wherein the ACK is used to indicate that the Beidou network device 200 has received the frame sequence number of the SLC PDU.
  • the ACK is lost, and the terminal 100 retransmits N SLC PDUs in the SLC SDU to the Beidou network device 200.
  • the Beidou network device 200 may combine the received (N-n1) initially transmitted SLC PDUs by receiving (N-n2) retransmitted SLC PDUs. If the SLC PDU in the SLC SDU is still missing after the combination, the Beidou network device 200 can continue to return an ACK to the terminal 100, instructing the terminal 100 to retransmit the missing SLC PDU. If the SLC PDUs in the SLC SDU are complete after merging, the Beidou network device 200 can splice the complete N SLC PDUs into one SLC SDU and report it to the MDCP layer.
  • the terminal 100 can send 4 SLC PDUs to the Beidou network device 200 at equal intervals.
  • the Beidou network device 200 only received the No. 2 and No. 3 SLC PDUs.
  • Beidou network device 200 determines that No. 0 and No. 1 SLC PDUs are lost according to the total number of frames and frame numbers in the received SLC PDUs. Therefore, the Beidou network device 200 can send ACK-3 to the terminal 100 at the time point of returning ACK, wherein the data part of the ACK-1 occupies 4 bits, and the value of the data part of the ACK-3 can be "0011", and the value "0011" indicates that the Beidou network device 200 has not received the No.
  • the terminal 100 did not receive any ACK returned by the Beidou network device 200 within the ACK receiving window in the SLC SDU initial transmission session.
  • the terminal 100 can start the first SLC SDU retransmission session, and retransmit the 4 SLC PDUs to the Beidou network device 200.
  • the No. 0 SLC PDU retransmitted for the first time is lost, and the Beidou network device 200 only receives the No. 1, No. 2 and No. 3 SLC PDUs retransmitted for the first time.
  • the Beidou network device 200 can take out the No.
  • the Beidou network device 200 may send ACK-1 to the terminal 100 at the point in time when the ACK is returned, wherein the value of the data part of the ACK-1 may be "0111", and the value "0111" indicates that the Beidou network device 200 has not received the first SLC PDU No. 0, SLC PDU No. 1, No. 2 and No. 3 have been received.
  • the terminal 100 can start the second SLC SDU retransmission session, and retransmit the No. 0 SLC PDU to the Beidou network device 200.
  • the Beidou network device 200 After the Beidou network device 200 receives the No. 0 SLC PDU, it can splice the No. 0 SLC PDU with the received No. 1 SLC PDU, No. 2 SLC PDU and No. 3 SLC PDU according to the frame sequence number into one
  • the SLC SDU is reported to the MDCP layer.
  • the Beidou network device 200 can send ACK-2 to the terminal 100 after receiving all the SLC PDUs of the SLC SDU.
  • the data part of the ACK-2 occupies 4 bits, and the value of the data part of the ACK-2 can be "1111", and the value "1111" indicates that the Beidou network device 200 has received all the four SLC PDUs.
  • the terminal 100 can enter the next SLC SDU sending session, and initially transmit all the SLC PDUs in the next SLC SDU.
  • a method for controlling inbound transmission in the Beidou communication system provided in the embodiment of the present application is introduced below.
  • Fig. 11 shows a schematic flowchart of a method for controlling inbound transmission in the Beidou communication system provided in the embodiment of the present application.
  • the inbound transmission control method in the Beidou communication system includes the following steps:
  • the terminal 100 sends N SLC PDUs in the first SLC SDU to the Beidou network device 200, 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 SAI field, the total number of frames field and the frame sequence number field.
  • the SAI field is used to indicate whether the first SLC PDU is retransmission data
  • the total number of frames 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 that the first SLC PDU is in the first SLC PDU. Sequence number in SLC SDU.
  • the Beidou network device 200 receives M SLC PDUs in the first SLC SDU sent by the terminal 100.
  • the Beidou network device 200 sends the first ACK to the terminal 100.
  • the first ACK is used to indicate that the Beidou network equipment in the first SLC SDU has not received the frame sequence number of the SLC PDU.
  • the first ACK can be in the form of a bitmap (Bitmap), and each 1 bit in the first Nbit of the data part of the first ACK is used to indicate the reception of one SLC PDU in the first SLC SDU.
  • Bitmap bitmap
  • each 1 bit in the first Nbit of the data part of the first ACK is used to indicate the reception of one SLC PDU in the first SLC SDU.
  • the terminal 100 determines the SLC PDUs in the first SLC SDU that have not been received by the Beidou network device 200.
  • the terminal 100 retransmits the SLC PDUs not received by the Beidou network device 200 in the first SLC SDU.
  • the process of retransmitting the SLC PDU can refer to the above-mentioned embodiments shown in FIG. 8-FIG. 10, and will not be repeated here.
  • the method further includes: when the terminal 100 receives the second ACK sent by the Beidou network device 200 , the terminal sends one or more SLC PDUs in the second SLC SDU to the Beidou network device 200, and the second ACK is used to indicate that the Beidou network device has received N SLC PDUs in the first SLC SDU.
  • the terminal sends all the SLC PDUs in the next SLC SDU to the Beidou network device 200 to maintain the continuous transmission of data.
  • the value of the SAI field of the SLC PDU in the first SLC SDU is different from the value of the SAI field of the SLC PDU in the second SLC SDU.
  • the method further includes: when the terminal 100 is sending the N SLC PDUs in the first SLC SDU When the ACK sent by the Beidou network device 200 is not received within the ACK reception time window after the Beidou network device 200, the terminal 100 retransmits the N SLC PDUs in the first SLC SDU to the Beidou network device 200.
  • the method further includes: the terminal 100 obtains the terminal 100 at the SLC layer under the MDCP layer of the terminal 100 The multiple SLC SDUs sent, wherein the multiple SLC SDUs include the first SLC SDU and the second SLC SDU; the terminal 100 splits the first SLC SDU into N SLC PDUs at the SLC layer.
  • the method further includes: the terminal 100 acquires at the MDCP layer the multiple SLC SDUs delivered by the application layer of the terminal 100 Application layer message; terminal 100 uses the application layer message as MDCP SDU at the MDCP layer, and after the MDCP SDU is added with padding data and redundant length indication field, it is split into multiple MDCP PDUs; wherein, the redundant length indication field is used
  • the multiple MDCP PDUs include a first MDCP PDU, and the header information of the first MDCP PDU includes a subsequent indication field, and the subsequent indication field is used to indicate that the first MDCP PDU is included in the multiple MDCP PDUs.
  • the terminal 100 sends multiple MDCP PDUs from the MDCP layer to the SLC layer as multiple SLC SDUs of the SLC layer.
  • the method before the terminal 100 obtains the application layer message issued by the application layer of the terminal 100 at the MDCP layer, the method further includes: the terminal 100 obtains the original data; the terminal 100 obtains the original data at the application layer , to compress to obtain compressed data; the terminal 100 encrypts the compressed data at the application layer to obtain encrypted data; the terminal 100 adds message header information to the encrypted data header to obtain the application layer message; wherein, the message header
  • the information includes a compression indication field and an encryption indication field, the compression indication field is used to indicate the compression algorithm used when compressing the original data, and the encryption indication field is used to indicate the encryption algorithm used when the compressed data is encrypted.
  • the terminal 100 sends N SLC PDUs in the first SLC SDU to the Beidou network device, specifically including: the terminal 100 sends the first SLC PDU from the SLC layer to the physical PHY layer as a PHY layer The first coded block; the terminal 100 adds check bit information at the end of the first coded block at the PHY layer, and encodes the first coded block and the check bit information to obtain the first coded data; the terminal 100 in the The PHY layer inserts pilot information into the first encoded data to obtain the first pilot data; the terminal 100 modulates the first pilot data and the synchronization header of the first pilot data at the PHY layer to obtain the first The modulation data and the first modulation synchronization header; the terminal 100 spreads the first modulation data and the modulation synchronization header at the PHY layer to obtain the first spread spectrum modulation data; the terminal sends the first spread spectrum modulation data to the Beidou network equipment at the PHY layer .
  • the terminal 100 is based on the moment when the terminal 100 sends the last SLC PDU in the first SLC SDU, the switching time of the terminal 100 from the sending state to the receiving state, the air interface propagation delay, and the Beidou network device 200
  • the signal processing scheduling delay determines the starting moment of the ACK receiving time window
  • the terminal 100 starts to receive the ACK sent by the Beidou network device 200 at the beginning of the ACK receiving time window.
  • the formula for determining the starting moment of the ACK receiving time window by the terminal 100 is:
  • tUeStartRcvAck is the starting moment of the ACK receiving time window
  • tUeTxEnd is the moment when the terminal 100 has sent the last SLC PDU in the first SLC SDU
  • tTx2RxSwitch is the switching time of the terminal 100 from the sending state to the receiving state
  • tPropagate is the air interface propagation time delay
  • tStationProcess is the signal processing scheduling delay on the Beidou network device 200.
  • the terminal 100 is based on the time length of the physical frame sent by the terminal 100, the air interface propagation delay, the signal processing scheduling delay of the Beidou network device 200, the time length of the physical frame sent by the Beidou network device 200 and The Beidou network device 200 sends the time alignment deviation of the physical frame to determine the end time of the ACK receiving time window; the terminal 100 stops receiving the ACK sent by the Beidou network device 200 at the end time of the ACK receiving time window.
  • the formula for determining the end time of the ACK receiving time window by the terminal 100 is:
  • tUeEndRcvAck is the end time of the ACK receiving time window
  • tUeUlFrameLen is the time length of the physical frame sent by the terminal 100
  • tPropagate is the air interface propagation delay
  • tStationProcess is the signal processing scheduling delay of the Beidou network device 200
  • tStationDlFrameLen is the Beidou network device 200
  • ⁇ is the time alignment deviation of the physical frame sent by the Beidou network device 200.
  • the Beidou network device 200 after the Beidou network device 200 receives M SLC PDUs in the first SLC SDU sent by the terminal 100, when M is equal to the N, the Beidou network device 200 sends a second ACK to the terminal 100 , wherein the second ACK is used to indicate that the Beidou network device has received N SLC PDUs in the first SLC SDU; the Beidou network device 200 has received one or more SLC PDUs in the second SLC SDU sent by the terminal 100.
  • the terminal sends all the SLC PDUs in the next SLC SDU to the Beidou network device 200 to maintain the continuous transmission of data.
  • the value of the SAI field of the SLC PDU in the second SLC SDU is different from the value of the SAI field of the SLC PDU in the first SLC SDU.
  • the Beidou network device receives M SLC PDUs in the first SLC SDU sent by the terminal, specifically including: the Beidou network device 200 acquires the first spread spectrum modulation data sent by the terminal 100 at the PHY layer The Beidou network equipment 200 despreads the first spread spectrum modulation data at the PHY layer to obtain the first modulation data and the first modulation synchronization header; the Beidou network equipment 200 despreads the first modulation data and the first modulation synchronization header at the PHY layer Demodulate to obtain the first pilot data and the first synchronization header; Beidou network equipment 200 removes the pilot information in the first pilot data at the PHY layer to obtain the first coded data; Beidou network equipment 200 performs the first The encoded data is decoded to obtain the first encoded block and the first verification information; the Beidou network device 200 verifies the first encoded block based on the first verification information at the PHY layer, and after the verification is successful, the first encoded block The block is presented from the PHY layer
  • the method further includes: the Beidou network device 200 splicing the M SLC PDUs at the SLC layer into The first SLC SDU, and report the first SLC SDU as the first MDCP PDU of the MDCP layer from the SLC layer of the Beidou network device to the MDCP layer of the Beidou network device.
  • the header information of the first MDCP PDU includes a successor indication field, and the successor indication The field is used to indicate the order of the first MDCP PDU among the multiple MDCP PDUs sent by the terminal 100.
  • the method further includes: the Beidou network device 200 obtains at the MDCP layer the second MDCP PDU reported from the SLC layer of the Beidou network device 200;
  • the Beidou network device 200 splices the first MDCP PDU and the second MDCP PDU into an MDCP at the MDCP layer SDU, and report the MDCP SDU as an application layer message from the MDCP layer to the application layer.
  • the application layer message includes message header information and encrypted data
  • the message header information includes an encryption indication field and a compression indication field
  • the compression indication field is used to instruct the terminal 100 to compress the original data into compressed
  • the compression algorithm used for the data the encryption indication field is used to indicate the encryption algorithm used when the terminal 100 encrypts the compressed data into encrypted data;
  • the method also includes: the Beidou network device 200 decrypts the encrypted data in the application layer message through the encryption algorithm indicated by the encryption indication field in the application layer message at the application layer to obtain compressed data; The compression algorithm indicated by the compression indication field in the layer message decompresses the compressed data to obtain the original data.
  • the Beidou network device 200 receives the frame sequence number of the first SLC PDU in the first SLC SDU, the total number of SLC PDUs in the first SLC SDU, the receiving time of the first SLC PDU, and the terminal 100 The frame interval of the physical frame sent and the time length of the physical frame sent by the terminal 100 determine the remaining time length of the SLC PDU receiving window.
  • the Beidou network device 200 determines the remaining time length of the SLC PDU receiving window through the following formula:
  • tStationRevWindow tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen)
  • tStationRevWindow is the remaining time length of the SLC PDU receiving window
  • tStatRevRctSP is the receiving moment of the first SLC PDU
  • nUeTotalFrameNum is the total number of SLC PDUs in the first SLC SDU
  • nRevFrameSN is the frame number of the first SLC PDU
  • tUeTxInterval is the terminal 100 The frame interval at which physical frames are sent.
  • tUeUlFrameLen is the time length of the physical frame sent by the terminal 100 .
  • the method further includes: the Beidou network device 200 determines the time point for sending the ACK based on the remaining time length of the SLC PDU receiving window and the signal processing scheduling delay of the Beidou network device 200.
  • the Beidou network device 200 determines the time point of sending the ACK through the following formula:
  • tStationSendAck is the time point when the Beidou network device 200 sends ACK
  • tStationRevWindow is the remaining time length of the SLC PDU receiving window
  • tStationProcess is the signal processing scheduling delay on the Beidou network device 200
  • ⁇ is the outbound physical frame on the Beidou network device 200 The sending time alignment deviation of .
  • the terminal 100 can send N SLC PDUs of the first SLC PDU to the Beidou network device 200 . If the Beidou network device 200 determines that the SLC PDU in the first SLC SDU is missing based on the frame header information of the received SLC PDU, it returns the first ACK to the terminal, wherein the first ACK is used to indicate that the Beidou network device has not received The frame sequence number of the SLC PDU in the first SLC SDU.
  • the terminal 100 After receiving the first ACK from the Beidou network device 200, the terminal 100 retransmits the SLC PDUs in the first SLC SDU that the Beidou network device 200 has not received to the Beidou network device 200. In this way, when the data sent by the terminal 100 is lost, the normal progress of the data transmission process is guaranteed.
  • the above content elaborates the method provided by the present application in detail.
  • the embodiments of the present application also provide corresponding devices or equipment.
  • the embodiment of the present application may divide the terminal 100 into functional modules according to the above method example, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module.
  • the above-mentioned integrated modules can be implemented in the form of hardware or in the form of software 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. 12 is a schematic structural diagram of a communication device 1200 provided in an embodiment of the present application.
  • the communication device 1200 may be the terminal 100 in the foregoing embodiments.
  • the communication device 1200 may be a chip/chip system, for example, a Beidou communication chip.
  • the communication device 1200 may include a transceiver unit 1210 and a processing unit 1220 .
  • the transceiver unit 1210 may be configured to send N SLC PDUs in the first SLC SDU to the Beidou network device 200, 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 SAI field, the total number of frames field and the frame sequence number field.
  • the SAI field is used to indicate whether the first SLC PDU is retransmission data
  • the total number of frames 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 that the first SLC PDU is in the first SLC PDU. Sequence number in SLC SDU.
  • the transceiver unit 1210 is further configured to receive the first ACK returned by the Beidou network device 200 .
  • the first ACK is used to indicate that the Beidou network equipment in the first SLC SDU has not received the frame sequence number of the SLC PDU.
  • the processing unit 1220 may be configured to determine, based on the first ACK, the SLC PDUs in the first SLC SDU that have not been received by the Beidou network device 200.
  • the transceiver unit 1210 is also used to retransmit the SLC PDUs not received by the Beidou network device 200 in the first SLC SDU to the Beidou network device 200.
  • the transceiver unit 1210 may also be configured to perform the functional steps related to sending and receiving performed by the terminal 100 in the above method embodiment shown in FIG. 11 .
  • processing unit 1220 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. 11 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. 13 is a schematic structural diagram of a communication device 1300 provided in an embodiment of the present application.
  • the communication device 1300 may be the Beidou network device 200 in the above-mentioned embodiments.
  • the communication device 1300 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 1300 may include a transceiver unit 1310 and a processing unit 1320 .
  • the transceiver unit 1310 may be configured to receive M SLC PDUs in the first SLC SDU sent by the terminal 100, where M is a positive integer; wherein, the M SLC PDUs include the first SLC PDU, and the first SLC PDU
  • the frame header information includes an SAI field, a frame total number field and a frame sequence number field; the SAI field is used to indicate whether the SLC PDU is retransmission data, and the frame total number field is used to indicate that the first SLC SDU includes the total number N of SLC PDUs, N It 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 processing unit 1320 may be configured to generate the first ACK based on the received header information of the M SLC PDUs.
  • the transceiver unit 1310 is further configured to send a first ACK to the terminal 100 when the M is less than the N, wherein the first ACK is used to indicate the frame sequence number of the unreceived SLC PDU in the first SLC SDU.
  • the transceiver unit 1310 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. 11 above.
  • the processing unit 1320 may also be configured to perform functional steps related to protocol parsing and encapsulation and calculation determination performed by the Beidou network device 200 in the method embodiment shown in FIG. 11 above.
  • the communication device 1300 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 of any form having the functions of the terminal 100 described above 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. 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, or a device therein.
  • the communication device 1400 includes a processor 1401 and a transceiver 1402 internally connected and communicating with the processor.
  • the processor 1401 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 1402 may be called a transceiver unit, a transceiver, or a transceiver circuit, etc., and is used to implement a transceiver function.
  • the transceiver 1402 may include a receiver and a transmitter, and the receiver may be called a receiver or a receiving circuit, etc., for realizing a receiving function; the transmitter may be called a transmitter, or a sending circuit, for realizing a sending function.
  • the communication device 1400 may further include an antenna 1403 and/or a radio frequency unit (not shown in the figure).
  • the antenna 1403 and/or the radio frequency unit may be located inside the communication device 1400, or may be separated from the communication device 1400, that is, the antenna 1403 and/or the radio frequency unit may be remote or distributed.
  • the communication device 1400 may include one or more memories 1404, on which instructions may be stored, the instructions may be computer programs, and the computer programs may be run on the communication device 1400, so that the communication device 1400 executes the above-mentioned Methods described in the Methods Examples.
  • data may also be stored in the memory 1404 .
  • the communication device 1400 and the memory 1404 can be set separately or integrated together.
  • the processor 1401, the transceiver 1402, and the memory 1404 may be connected through a communication bus.
  • the communication device 1400 can be used to perform the functions of the terminal 100 in the foregoing embodiments: the processor 1401 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. 11 Steps and/or other processes for the technology described herein; the transceiver 1402 may be used to perform the functional steps related to sending and receiving performed by the terminal 100 in the embodiment shown in FIG. Other processes of technology.
  • the processor 1401 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 transmission.
  • the processor 1401 may store instructions, and the instructions may be computer programs, and the computer programs run on the processor 1401 to enable the communication device 1400 to execute the method steps performed by the terminal 100 in the above method embodiments.
  • the computer program may be fixed in the processor 1400, and in this case, the processor 1401 may be implemented by hardware.
  • the communication device 1400 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 1400 may be a stand-alone device or may be part of a larger device.
  • the communication device 1400 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. 15 is a schematic structural diagram of a communication device 1500 provided by an embodiment of the present application.
  • the communication device 1500 may be the BeiDou network device 200, or a device therein.
  • the communication device 1500 includes a processor 1501 and a transceiver 1502 internally connected and communicating with the processor.
  • the processor 1501 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 the satellite communication can be used to process the satellite communication protocol and satellite communication data
  • 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 1502 may be called a transceiver unit, a transceiver, or a transceiver circuit, etc., and is used to implement a transceiver function.
  • the transceiver 1502 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 1500 may further include an antenna 1503 and/or a radio frequency unit (not shown in the figure).
  • the antenna 1503 and/or the radio frequency unit may be located inside the communication device 1500, or may be separated from the communication device 1500, that is, the antenna 1503 and/or the radio frequency unit may be remote or distributed.
  • the communication device 1500 may include one or more memories 1504, on which instructions may be stored, the instructions may be computer programs, and the computer programs may be run on the communication device 1500, so that the communication device 1500 executes the above-mentioned Methods described in the Methods Examples.
  • data may also be stored in the memory 1504 .
  • the communication device 1500 and the memory 1504 can be set separately or integrated together.
  • the processor 1501, the transceiver 1502, and the memory 1504 may be connected through a communication bus.
  • the communication device 1500 can be used to perform the functions of the Beidou network device 200 in the foregoing embodiments: the processor 1501 can be used to perform the related protocol parsing and encapsulation performed by the Beidou network device 200 in the embodiment shown in FIG. 11 and The functional steps determined by the calculation and/or other processes used in the technology described herein; the transceiver 1502 can be used to perform the functional steps related to sending and receiving performed by the Beidou network device 200 in the embodiment shown in FIG. Other procedures for the techniques described herein.
  • the processor 1501 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 1501 may store instructions, and the instructions may be computer programs, and the computer programs run on the processor 1501 to enable the communication device 1500 to perform the method steps performed by the terminal 100 in the above method embodiments.
  • the computer program may be fixed in the processor 1500, and in this case, the processor 1501 may be implemented by hardware.
  • the embodiment of the present application also provides a computer-readable storage medium, where computer program code is stored, and when the above-mentioned processor executes the computer program code, the electronic device executes the method in any one 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 there may be communication functions supporting short messages in other satellite systems. 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.

Abstract

本申请涉及卫星通信领域，公开了一种北斗通信系统中入站传输控制方法、系统及相关装置。终端可以向北斗网络设备发送第一SLC PDU的N个SLC PDU。若北斗网络设备基于已接收到的SLC PDU的帧头信息确定出第一SLC SDU中SLC PDU有缺失，则返回第一ACK给终端，其中，第一ACK用于指示北斗网络设备未接收到第一SLC SDU中SLC PDU的帧序号。终端在接收到北斗网络设备的第一ACK后，重传第一SLC SDU中北斗网络设备未收到的SLC PDU给北斗网络设备。这样，在终端发送的数据有丢失时，保证数据传输过程的正常进行。

Description

一种北斗通信系统中入站传输控制方法、系统及相关装置
本申请要求于2021年07月31日提交中国专利局、申请号为202110877287.6、申请名称为“一种北斗通信系统中入站传输控制方法、系统及相关装置”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入站传输控制方法、系统及相关装置。
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)等其它全球定位导航系统的特色之一，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定位和通信。北斗短报文业务的通信系统对技术体制进行升级，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。
由于北斗短报文业务的通信系统是通过卫星链路进行通信，其主要特性是：1、时延长；2、链路损耗大；3、支持的业务主要是突发式短消息业务；4、不支持链接状态管理、移动性管理和广播控制信息等。目前的无线通信的协议并不能适用于北斗短报文业务的通信系统中，原因在于：由于卫星通信传播距离远，北斗短报文业务的通信系统中对终端发送功率要求高。受当前民用的终端(例如手机等终端)射频器件的限制，终端无法向北斗短报文卫星长时间持续发送信号。为了尽量不损坏终端上射频器件，终端的射频器件在发送状态持续工作一段时间后，必须关闭停止一段时间才能继续切换到发送状态。而现有的无线通信协议中信令交互流程的放到北斗短报文业务中执行，耗时太长，北斗短报文业务的通信系统中空口资源有限，无法满足这种信令交互，因此，没有专门设计控制信令的交互协议流程。并且，北斗短报文业务的通信中没有广播信息，终端也无法通过广播信息来获取北斗网络设备的配置信息。因此，当终端发送的数据包有丢失时，终端无法通过专门的控制信令或者广播信息来通知北斗网络设备协商数据包的重传，无法保证数据传输过程的正常进行。
发明内容
本申请提供了一种北斗通信系统中入站传输控制方法、系统及相关装置，实现了北斗通信系统中，终端的数据包有丢失时保证数据传输过程的正常进行。
第一方面，本申请提供了一种北斗通信系统中入站传输控制方法，包括：终端发送第一卫星链路控制层服务数据单元SLC SDU中的N个卫星链路控制层协议数据单元SLC PDU给北斗网络设备，N为正整数；其中，N个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括服务数据单元交替指示SAI字段、帧总数字段和帧序号字段；SAI字段用于指示 第一SLC PDU是否为重传数据，帧总数字段用于指示第一SLC SDU中包括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；
当终端接收到北斗网络设备发送的第一确认字符ACK时，终端重传第一SLC SDU中北斗网络设备未接收到的SLC PDU给北斗网络设备，其中，第一ACK用于指示第一SLC SDU中北斗网络设备未接收到的SLC PDU的帧序号。
通过本申请提供的一种北斗通信系统中入站传输控制方法，终端可以将应用层报文在MDCP层拆分成多个MDCP PDU。终端可以顺序下发MDCP PDU到SLC层作为SLC层的SLC SDU，并在SLC层将SLC SDU拆分成N个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。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SLCPDU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。终端可以将第一SLC PDU的N个SLC PDU发送给北斗网络设备。若北斗网络设备基于已接收到的SLC PDU的帧头信息确定出第一SLC SDU中SLC PDU有缺失，则返回第一ACK给终端，其中，第一ACK用于指示北斗网络设备未接收到第一SLC SDU中SLC PDU的帧序号。终端在接收到北斗网络设备的第一ACK后，重传第一SLC SDU中北斗网络设备未收到的SLC PDU给北斗网络设备。
这样，在终端发送的数据包有丢失时，保证数据传输过程的正常进行。
在一种可能的实现方式中，在终端发送第一SLC SDU中的N个SLC PDU给北斗网络设备后，该方法还包括：当终端接收到北斗网络设备发送的第二ACK时，终端发送第二SLC SDU中的一个或多个SLC PDU给北斗网络设备，第二ACK用于指示北斗网络设备已接收到第一SLC SDU中的N个SLC PDU。
这样，在北斗网络设备收齐终端发送的一个SLC SDU中的所有SLC PDU后，终端发送下一个SLC SDU中的所有SLC PDU给北斗网络设备，以保持数据的持续传输。
在一种可能的实现方式中，第一SLC SDU中SLC PDU的SAI字段的值与第二SLC SDU中SLC PDU的SAI字段的值不同。
这样，通过SLC PDU的SAI字段的值翻转与否，来表示SLC PDU是否是重传数据，可以保证北斗网络设备识别出接收到的SLC PDU是否是重传数据，保证了北斗通信系统中的数据持续传输。
在一种可能的实现方式中，在终端发送第一SLC SDU中的N个SLC PDU给北斗网络设备后，该方法还包括：当终端在发送第一SLC SDU中的N个SLC PDU给北斗网络设备之后的ACK接收时间窗内，未接收到北斗网络设备发送的ACK时，终端重传第一SLC SDU中的N个SLC PDU给北斗网络设备。
在一种可能的实现方式中，在终端发送第一SLC SDU中的N个SLC PDU给北斗网络设备之前，该方法还包括：终端在SLC层获取到终端的MDCP层下发的多个SLC SDU，其中，多个SLC SDU中包括第一SLC SDU和第二SLC SDU；终端在SLC层将第一SLC SDU拆分成N个SLC PDU。
在一种可能的实现方式中，在终端在SLC层获取到终端的MDCP层下发的多个SLC SDU之前，该方法还包括：终端在MDCP层获取到终端的应用层下发的应用层报文；终端在MDCP层将应用层报文作为MDCP SDU，并在MDCP SDU加入填充数据和冗余长度指示字段后，拆分成多个MDCP PDU；其中，冗余长度指示字段用于指示填充数据的数据长度，该多个MDCP PDU中包括第一MDCP PDU，该第一MDCP PDU的包头信息包括后继指示字段，该后继指示字段用于指示第一MDCP PDU在该多个MDCP PDU中的顺序；终端将多个MDCP PDU从MDCP层下发至SLC层，作为SLC层的多个SLC SDU。
在一种可能的实现方式中，在终端在MDCP层获取到终端的应用层下发的应用层报文之前，该方法还包括：终端获取原始数据；终端在应用层将原始数据，进行压缩得到压缩数据；终端在应用层将压缩数据进行加密得到加密后数据；终端在加密后数据头部加上报文头信息，得到应用层报文；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压缩算法，加密指示字段用于指示对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，终端发送第一SLC SDU中的N个SLC PDU给北斗网络设备，具体包括：终端将第一SLC PDU从SLC层下发至物理PHY层，作为PHY层的第一编码块；终端在PHY层在第一编码块的尾部添加校验位信息，并对第一编码块和校验位信息进行编码得到第一编码数据；终端在PHY层在第一编码数据中插入导频信息，得到第一导频数据；终端在PHY层对第一导频数据和第一导频数据的同步头进行调制，得到第一调制数据和第一调制同步头；终端在PHY层将第一调制数据和调制同步头进行扩频得到第一扩频调制数据；终端在PHY层将第一扩频调制数据发送给北斗网络设备。
在一种可能的实现方式中，终端基于终端发送完第一SLC SDU中最后一个SLC PDU的时刻、终端从发送态至接收态的切换时长、空口传播时延和北斗网络设备的信号处理调度时延，确定出ACK接收时间窗的起始时刻；
终端在ACK接收时间窗的起始时刻开始接收北斗网络设备发送的ACK。
其中，终端确定出ACK接收时间窗的起始时刻的公式为：
tUeTxEnd+tTx2RxSwitch＜tUeStartRcvAck＜tUeTxEnd+2*tPropagate+tStationProcess
其中，tUeStartRcvAck为ACK接收时间窗的起始时刻；tUeTxEnd为终端发送完第一SLC SDU中最后一个SLC PDU的时刻；tTx2RxSwitch为终端从发送态至接收态的切换时长；tPropagate为空口传播时延；tStationProcess为北斗网络设备上的信号处理调度时延。
在一种可能的实现方式中，终端基于终端发送的物理帧的时间长度、空口传播时延、北斗网络设备的信号处理调度时延、北斗网络设备发送的物理帧的时间长度和北斗网络设备发送物理帧的时间对齐偏差，确定出ACK接收时间窗的结束时刻；终端在ACK接收时间窗的结束时刻停止接收北斗网络设备发送的ACK。
其中，终端确定出ACK接收时间窗的结束时刻的公式为：
tUeEndRcvAck＝ tUeTxEnd+tUeUlFrameLen+2*tPropagate+tStationProcess+tStationDlFrameLen+δ
其中，tUeEndRcvAck为ACK接收时间窗的结束时刻，tUeUlFrameLen为终端发送的物理帧的时间长度，tPropagate为空口传播时延，tStationProcess为北斗网络设备的信号处理调度时延，tStationDlFrameLen为北斗网络设备发送的物理帧的时间长度，δ为北斗网络设备发送物理帧的时间对齐偏差。
第二方面，本申请提供另了一种北斗通信系统中入站传输控制方法，包括：北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU，M为正整数；其中，M个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括SAI字段、帧总数字段和帧序号字段；SAI字段用于指示SLC PDU是否为重传数据，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M小于N时，北斗网络设备向终端发送第一ACK，其中，第一ACK用于指示第一SLC SDU中北斗网络设备未接收到的SLC PDU的帧序号。
在一种可能的实现方式中，北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU后，当M等于N时，北斗网络设备向终端发送第二ACK，其中，第二ACK用于指示北斗网络设备已接收到第一SLC SDU中的N个SLC PDU；北斗网络设备接收到终端发送的第二SLC SDU中的一个或多个SLC PDU。
这样，在北斗网络设备收齐终端发送的一个SLC SDU中的所有SLC PDU后，终端发送下一个SLC SDU中的所有SLC PDU给北斗网络设备，以保持数据的持续传输。
在一种可能的实现方式中，第二SLC SDU中SLC PDU的SAI字段的值与第一SLC SDU中SLC PDU的SAI字段的值不同。
这样，通过SLC PDU的SAI字段的值翻转与否，来表示SLC PDU是否是重传数据，可以保证北斗网络设备识别出接收到的SLC PDU是否是重传数据，保证了北斗通信系统中的数据持续传输。
在一种可能的实现方式中，北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU，具体包括：北斗网络设备在PHY层获取到终端发送的第一扩频调制数据；北斗网络设备在PHY层对第一扩频调制数据进行解扩频，得到第一调制数据和第一调制同步头；北斗网络设备在PHY层对第一调制数据和第一调制同步头解调，得到第一导频数据和第一同步头；北斗网络设备在PHY层去除第一导频数据中的导频信息，得到第一编码数据；北斗网络设备在PHY层对第一编码数据进行解码，得到第一编码块和第一校验信息；北斗网络设备在PHY层基于第一校验信息对第一编码块进行校验，并在校验成功后，将第一编码块作为北斗网络设备的SLC层中第一SLC SDU中的第一SLC PDU从PHY层呈递给北斗网络设备的SLC层。
在一种可能的实现方式中，北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU之后，该方法还包括：北斗网络设备在SLC层将M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从北斗网络设备的SLC层上报给北斗 网络设备的MDCP层，第一MDCP PDU的包头信息中包括后继指示字段，后继指示字段用于指示第一MDCP PDU在终端发送的多个MDCP PDU中的顺序。
在一种可能的实现方式中，该方法还包括：北斗网络设备在MDCP层获取到从北斗网络设备的SLC层上报的第二MDCP PDU；
当第二MDCP PDU中的后继指示字段指示第二MDCP PDU为终端发送的多个MDCP PDU中的最后一个时，北斗网络设备在MDCP层将第一MDCP PDU与第二MDCP PDU拼接成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，应用层报文包括报文头信息和加密后数据，报文头信息包括加密指示字段和压缩指示字段，压缩指示字段用于指示终端将原始数据压缩成压缩数据时使用的压缩算法，加密指示字段用于指示终端将压缩数据加密成加密后数据时使用的加密算法；
该方法还包括：北斗网络设备在应用层通过应用层报文中加密指示字段指示的加密算法，对应用层报文中加密后数据进行解密，得到压缩数据；北斗网络设备在应用层通过应用层报文中压缩指示字段指示的压缩算法，对压缩数据进行解压缩，得到原始数据。
在一种可能的实现方式中，北斗网络设备基于接收到第一SLC SDU中第一SLC PDU的帧序号、第一SLC SDU中SLC PDU的总数量、第一SLC PDU的接收时刻、终端发送的物理帧的帧间隔、终端发送的物理帧的时间长度，确定出SLC PDU接收窗的剩余时间长度。
其中，北斗网络设备通过如下公式确定出SLC PDU接收窗的剩余时间长度：
tStationRevWindow＝tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen)
其中，tStationRevWindow为SLC PDU接收窗的剩余时间长度，tStatRevRctSP为第一SLC PDU的接收时刻，nUeTotalFrameNum为第一SLC SDU中SLC PDU的总数量，nRevFrameSN为第一SLC PDU的帧序号，tUeTxInterval为终端发送物理帧的帧间隔。tUeUlFrameLen为终端发送的物理帧的时间长度。
在一种可能的实现方式中，该方法还包括：北斗网络设备基于SLC PDU接收窗的剩余时间长度和北斗网络设备的信号处理调度时延，确定出发送ACK的时间点。
其中，北斗网络设备通过如下公式确定出发送ACK的时间点：
tStationSendAck＝tStationRevWindow+tStationProcess+δ
其中，tStationSendAck为北斗网络设备发送ACK的时间点，tStationRevWindow为SLC PDU接收窗的剩余时间长度，tStationProcess为北斗网络设备上的信号处理调度时延，δ为北斗网络设备上出站物理帧的发送时间对齐偏差。
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，
该终端，用于发送第一SLC SDU中的N个SLC PDU给北斗网络设备，N为正整数；其中，该SLC PDU的帧头信息包括SAI字段、帧总数字段和帧序号字段；该SAI字段用于指示该SLC PDU是否为重传数据，该帧总数字段用于指示该第一SLC SDU中包括SLC PDU 的总数量N，该帧序号字段用于指示该SLC PDU在该第一SLC SDU中的序号；该北斗网络设备，用于接收到该终端发送的该第一SLC SDU中的M个SLC PDU，M为正整数；该北斗网络设备，还用于当该M小于该N时向该终端发送第一ACK，其中，该第一ACK用于指示该第一SLC SDU中该北斗网络设备未接收到的SLC PDU的帧序号；该终端，还用于当接收到该北斗网络设备发送的该第一ACK时，重传该第一SLC SDU中该北斗网络设备未接收到的SLC PDU给该北斗网络设备。
在一种可能的实现方式中，终端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，北斗网络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。
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的架构示意图；
图1B为本申请实施例提供的一种北斗通信协议层示意图；
图2为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示意图；
图3为本申请实施例提供的一种终端的结构示意图；
图4为本申请实施例提供的一种北斗通信系统的入站数据的协议封装架构示意图；
图5为本申请实施例提供的一种北斗通信系统的入站数据的协议解析架构示意图；
图6为本申请实施例提供的一种北斗通信系统在MDCP层和SLC层对数据的协议处理流程示意图；
图7为本申请实施例提供的一种数据入站时SLC层的接收确认机制示意图；
图8为本申请实施例提供的终端发送的SLC PDU出现丢失时的处理流程示意图；
图9为本申请实施例提供的北斗网络设备返回的ACK出现丢失时的处理流程示意图；
图10为本申请实施例提供的数据入站时SLC PDU和ACK同时出现丢失时的处理流程示意图；
图11为本申请实施例提供的一种北斗通信系统中入站传输控制方法的流程示意图；
图12为本申请实施例提供的一种通信装置的结构示意图；
图13为本申请实施例提供的另一种通信装置的结构示意图；
图14为本申请实施例提供的另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。
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除、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，另外，在本申请实施例的描述中，“多个”是指两个或多于两个。
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中提供的一种北斗通信系统10。
图1A示出了本申请实施例中提供的一种北斗通信系统10的架构示意图。
如上图1A所示，北斗通信系统10可以包括终端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。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，终端100可以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，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通用报文类型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。北斗网络设备200也可以将终 端100发送的紧急求救类型的报文，通过紧急救援平台26发送给紧急救援中心27。
终端300也可以通过传统的蜂窝通信网络，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可以包括北斗地面收发站22、北斗中心站23和北斗短报文融合通信平台24。其中，北斗地面收发站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。
如图1B所示，北斗通信协议层可以包括应用(application layer protocol，APP)层、消息数据汇聚(message data convergence protocol，MDCP)层、卫星链路控制层(satellite link control protocol，SLC)层和物理(physical layer protocol，PHY)层。
北斗地面收发站22可用于北斗网络设备200在PHY层对数据的处理功能。北斗中心站23可用于北斗网络设备200在SLC层和MDCP层对数据的处理功能。北斗短报文融合通信平台24可用于在APP层对数据的处理功能。
其中，由于北斗通信系统10是通过卫星链路进行通信，其主要特性是：时延长(单向约270ms)，链路损耗大。当前北斗通信系统10支持的业务主要是突发短消息业务，不支持链接状态管理、移动性管理和广播控制信息等。
终端100可以主动通过北斗短报文卫星21给北斗网络设备200发送数据。但是，由于没有空口信令，地面的中心站无法主动寻呼用户。由于卫星通信传播距离远，北斗通信系统10中对终端100的发送功率要求高。受限当前终端100上射频器件的限制，终端100无法向北斗短报文卫星21长时间持续发送信号。为了尽量不损坏终端100上射频器件，终端100的射频器件在发送状态持续工作一段时间后，必须停止工作一段时间后才能继续切换到发送状态继续工作。其中，终端100上发送状态的持续时长由终端100的底层硬件能力所决定。在上述北斗通信系统10中，为了保证终端100接收到的数据和发送的数据互不干扰，终端100不支持发送数据和接收数据同时发生。终端100需要在发送数据后，再等待接收北斗网络设备200发送的数据。
其中，北斗网络设备200的工作模式可以是双工模式，可以同时收发数据，且北斗网络设备200可以长时间发送和接收数据。
图2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2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层的确认字符(acknowledgecharacter，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。
在蜂窝和其他短距通信系统中，在用户设备发送数据前可以与接收设备进行控制信令的交互来预先分配用户设备的发送物理资源。但是，在上述北斗通信系统10中，由于控制信令的交互时间太长，并且北斗通信10上空口的资源有限。因此，北斗通信系统10中并没有设计专门的控制信令来分配终端100发送数据时的物理资源。并且，北斗通信系统10中没有专 门广播信道传输广播信息，终端100无法通过广播信息来获取北斗网络设备200的配置信息。当终端100向北斗网络设备200发送数据有丢包时，无法保证北斗网络设备200能恢复出完整的数据。
因此，本申请实施例中提供一种北斗通信系统中入站传输控制方法，终端100可以将应用层报文在MDCP层拆分成多个MDCP PDU。终端100可以顺序下发MDCP PDU到SLC层作为SLC层的SLC SDU，并在SLC层将SLC SDU拆分成N个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。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SLCPDU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。
终端100可以将第一SLC PDU的N个SLC PDU发送给北斗网络设备200。
若北斗网络设备200基于已接收到的SLC PDU的帧头信息确定出第一SLC SDU中SLC PDU有缺失，则返回第一ACK给终端100，其中，第一ACK用于指示北斗网络设备200未接收到第一SLC SDU中SLC PDU的帧序号。终端100在接收到北斗网络设备200的第一ACK后，重传第一SLC SDU中北斗网络设备200未收到的SLC PDU给北斗网络设备200。
若北斗网络设备200基于已接收到的SLC PDU的帧头信息确定出第一SLC SDU中的N个SLC PDU已收齐，则返回第二ACK给终端100，其中，第二ACK用于指示北斗网络设备200已接收到第一SLC SDU中N个SLC PDU。终端100接收到第二ACK后，可以发送第二SLC SDU中的所有SLC PDU给北斗网络设备200。
这样，在终端100或北斗网络设备200发送的数据包有丢失时，保证数据传输过程的正常进行。
图3示出了终端100的结构示意图。
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3所示终端100仅是一个范例，并且终端100可以具有比图3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3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10的入站数据的协议封装架构。
图4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4所示，终端100上的北斗报文传输协议层可以分为应用层(application layer protocol)、消息数据汇聚层(message data convergence protocol，MDCP)、卫星链路控制层(satellite link control protocol，SLC)和物理层(physical layer protocol，PHY)。
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可以将原始数据通过压缩算法，压缩成压缩数据，并在压缩数据前面添加压缩指示字段，其中，压缩指示字段可用于表示该压缩数据的压缩算法类型。之后，终端100可以将压缩数据加密，得到加密后数据，并在加密后数据的头部添加加密指示字段，该加密指示字段用于表示该加密后的数据的加密算法类型。终端100可以将加密后数据、压缩指示字段、加密指示字段封装成应用层报文下发给MDCP层。其中，该应用层报文包括报文头和报文数据。该报文头中包括压缩指示字段和加密指示字段等等。该报文数据包括上述加密后数据。
可选的，终端100也可以将压缩指示字段和压缩数据一起进行加密，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 SDU。由于受空口的限制，终端100每次只能在物理层发送的指定长度的物理帧，这样，约束了MDCP层数据的长度为指定长度。因此，在MDCP层，终端100可以在MDCPSDU的尾部添加填充数据(padding)至指定长度，并在MDCP SDU的头部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 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MDCPPDU是连续发送的多个MDCP PDU中的起始MDCPPDU、中间MDCP PDU或最后一个MDCP PDU；或者，是单独发送的一个MDCP PDU。
在SLC层，终端100可以通过层间接口获取到MDCP层下发的MDCPPDU，作为SLCSDU。在SLC层，终端100可以将SLCSDU分段成一个或多个(最多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，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SLCPDU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，作为PHY层的编码块(code block)，并在code block的头部添加同步头，在code block的尾部添加校验位字段。其中，在上述北斗通信系统10中，可以采用循环冗余校验(cyclic redundancy check，CRC)对编码块进行校验，因此，该校验位字段中可以包括CRC码。终端100可以对code block和校验位字段进行编码(例如polar编码)，得到编码数据(coded data)，再在coded data中插入导频，得到导频编码数据(pilot+data)。然后，终端100通过底层硬件对同步头和导频编码数据依次进行调制得到调制数据(modulateddata)。终端100可以对调制数据进行扩频，得到扩频调制数据(spread+modulateddata)。终端100可以将扩频调制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。
下面介绍本申请实施例中提供的一种北斗通信系统10的入站数据的协议解析架构。
图5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5所示，北斗网络设备200的北斗短报文传输协议层可以分为APP层、MDCP层、SLC层和PHY层。其中，北斗网络设备200可以包括北斗地面收发站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。
北斗网络设备200在接收到终端100发送的数据时，北斗网络设备200的北斗短报文传输协议层的工作流程可以如下：
在PHY层，北斗网络设备200可以获取到终端100发送的经过调制和扩频后的导频编码数据。北斗网络设备200可以对接收到的扩频调制数据(spread+modulateddata)进行解扩频，得到调制数据(modulateddata)。然后，北斗网络设备200可以对调制数据进行解调，得到导频编码数据(pilot+data)。接着，北斗网络设备200去除导频编码数据中的导频信息，得到编 码数据(codedata)。然后，北斗网络设备200可以对编码数据进行解码，并通过校验位字段中的校验数据验证编码块(codeblock)的完整性。若完整，则北斗网络设备200可以提取出编码块(codeblock)，通过层间接口呈递给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拼接成一个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，对应用层报文进行解密、解压缩，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。
下面具体介绍北斗通信系统10在MDCP层和SLC层对数据的协议处理流程。
图6示出了本申请实施例中提供的北斗通信系统10在MDCP层和SLC层对数据的协议处理流程示意图。
1、终端100在MDCP层对发送数据的协议封装过程。
如图6所示，在MDCP层，终端100可以将填充(padding)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 PDU，即MDCP PDU包括M_segment和后继指示字段。终端100可以将拆分得到的MDCP PDU，按照接收的先后顺序存入MDCP层发送缓冲区(MDCP Txbuffer)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，终端100可以将填充(padding)数据以及增加冗余长度指示字段之后的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”。
又示例性的，终端100可以将填充(padding)数据以及增加冗余长度指示字段之后的MDCP SDU，拆分成2个MDCP PDU，其中，按照高比特位到低比特位的顺序，这2个MDCP PDU依次是MDCP PDU0和MDCP PDU1。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中的最后一个MDCP PDU，终端100可以将MDCP PDU1中后继指示字段的值设置为“11”。
又示例性的，终端100可以将填充(padding)数据以及增加冗余长度指示字段之后的MDCP SDU，作为1个MDCP PDU0。其中，由于MDCP PDU0是当前MDCP SDU中唯一的一个MDCP PDU，终端100可以将MDCP PDU0中后继指示字段的值设置为“00”。
2、终端100在SLC层对发送数据的协议封装过程。
在SLC层，终端100在SLC层可以通过SLC层发送状态控制器，基于北斗网络设备200发送的接收反馈(例如，ACK)，控制SLC层的SLC PDU发送策略，包括SLC PDU的初传和重传。终端100可以通过层间接口获取到MDCP层下发的MDCPPDU，作为SLCSDU。其中，当终端100向北斗网络设备200发送前一个SLC SDU，并确认北斗网络设备200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，发送给北斗网络设备200。
示例性，终端100可以将填充(padding)数据以及增加冗余长度指示字段之后的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。在SLC层，终端100首先通过层间接口获取到MDCP层下发的MDCP PDU0，终端100可以将将MDCP PDU0作为本次报文传输过程中SLC层的首个SLC SDU发送给北斗网络设备200。在终端100确定已经将北斗网络设备200将首个SLC SDU的数据发送给北斗网络设备200后，终端100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发送给北斗网络设备200。在终端100确定已经将北斗网络设备200将第2个SLC SDU的数据发送给北斗网络设备200后，终端100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发送给北斗网络设备200。
上述示例仅仅用于解释本申请，不应构成限定。
可选的，终端100可以在MDCP层将属于一个MDCP SDU的所有MDCPPDU都下发给SLC层，作为SLC层的多个SLC SDU，存入SLC层的发送缓冲区中。终端100在SLC层发送完一个SLC SDU后，当终端100向北斗网络设备200发送完一个SLC SDU，并确认北斗网络设备200接收成功之后，再继续从SLC层的发送缓冲区获取并发送下一个SLC SDU。
在SLC层，终端100可以将SLCSDU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：
(1)SAI字段可以占用1bit。SAI字段的值可以为“0”或“1”。终端100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，则终端100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，则终端100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，终端100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中4个SLC PDU的SAI字段的值可以都为“0”，第2个SLC SDU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。
(2)帧总数字段，可用于表示该SLC PDU所属的SLC SDU中包括SLCPDU的总数量。当北斗通信系统10中一个SLC SDU最多可以被分成4个固定长度的SLC分段数据(S_segment)时，帧总数字段可以占用2bit。
示例性的，当SLC SDU中只包括有1个SLC PDU时，该SLC SDU中唯一一个SLC PDU的帧总数字段的值可以为“00”。当SLC SDU中包括有2个SLC PDU时，该SLC SDU中2个SLC PDU的帧总数字段的值都可以为“01”。当SLC SDU中包括有3个SLC PDU时，该SLC SDU中3个SLC PDU的帧总数字段的值都可以为“10”。当SLC SDU中包括有4个SLC PDU时，该SLC SDU中4个SLC PDU的帧总数字段的值都可以为“11”。
上述示例仅仅用于解释本申请，不应构成限定。
(3)帧序号字段，可用于表示该SLC PDU在所属的SLC SDU中的序号。当北斗通信系统10中一个SLC SDU最多可以被分成4个固定长度的SLC分段数据(S_segment)时，帧序号字段可以占用2bit。
示例性的，当SLC SDU中只包括有1个SLC PDU时，该SLC SDU中唯一一个SLC PDU的帧序号字段的值可以为“00”。当SLC SDU中包括有2个SLC PDU时，该SLC SDU中第1个SLC PDU中帧序号字段的值可以为“00”，该SLC SDU中第2个SLC PDU中帧序号字段的值可以为“01”。当SLC SDU中包括有3个SLC PDU时，该SLC SDU中第1个SLC PDU中帧序号字段的值可以为“00”，该SLC SDU中第2个SLC PDU中帧序号字段的值可以为“01”，该SLC SDU中第3个SLC PDU中帧序号字段的值可以为“10”。当SLC SDU中包括有4个SLC PDU时，该SLC SDU中第1个SLC PDU中帧序号字段的值可以为“00”，该SLC SDU中第2个SLC PDU中帧序号字段的值可以为“01”，该SLC SDU中第3个SLC PDU中帧序号字段的值可以为“10”，该SLC SDU中第4个SLC PDU中帧序号字段的值可以为“11”。
上述示例仅仅用于解释本申请，不应构成限定。
在一种可能的实现方式中，SLC PDU的帧头信息中还可以包括确认模式使能(AMenable)字段，该确认模式使能字段，可用于指示终端100是否采用确认模式(AM)发送SLCPDU。若终端100采用确认模式发送SLC PDU，则北斗网络设备200可以在接收到终端100发送的一个或多个SLC PDU后，在SLC层发送反馈信息给终端100。该反馈信息用于通知终端100北斗网络设备200未接收到的SLC PDU。
3、北斗网络设备200在SLC层对接收数据的协议解析过程。
在SLC层，北斗网络设备200接收终端100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，若是，则北斗网络设备200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。若未接收完一个SLC SDU中的所有SLC PDU，则北斗网络设备200在SLC层接收窗结束后，可以发送反馈信息(例如，ACK)给终端100。该反馈信息用于通知终端100北斗网络设备200未接收到的SLC PDU。北斗网络设备200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，北斗网络设备200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SLCPDU的拼接。该SLC层接收状态控制器的持续时间为终端100上SLC PDU的最大重传时间。
示例性的，北斗网络设备200接收到的第1个SLC SDU中第1个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“00”。第1个SLC SDU中第2个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“01”。第1个SLC SDU中第3个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“10”。第1个SLC SDU中第4个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“11”。北斗网络设备200可以将这4个SLC PDU按照帧序号从小到大顺序，拼接成第1个SLC SDU，上报给MDCP层，作为MDCP层的MDCP PDU0。北斗网络设备200可以将MDCP PDU0存入MDCP层接收缓冲区(MDCP Rxbuffer)中。其中，MDCP PDU0中后继指示字段的值为“01”。
北斗网络设备200接收到的第2个SLC SDU中第1个SLC PDU的SAI值可以为“1”、帧总数值为“11”、帧序号为“00”。第2个SLC SDU中第2个SLC PDU的SAI值可以为“1”、帧总数值为“11”、帧序号为“01”。第2个SLC SDU中第3个SLC PDU的SAI值可以为“1”、帧总数值为“11”、帧序号为“10”。第2个SLC SDU中第4个SLC PDU的SAI值可以为“1”、帧总数值为“11”、帧序号为“11”。北斗网络设备200可以将这4个SLC PDU按照帧序号从小到大顺序，拼接成第2个SLC SDU，上报给MDCP层，作为MDCP层的MDCP PDU1。北斗网络设备200可以将MDCP PDU1存入MDCP层接收缓冲区(MDCP Rxbuffer)中。其中，MDCP PDU1中后继指示字段的值为“10”。
北斗网络设备200接收到的第3个SLC SDU中第1个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“00”。第3个SLC SDU中第2个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“01”。第3个SLC SDU中第3个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“10”。第3个SLC SDU中第4个SLC PDU的SAI值可以为“0”、帧总数值为“11”、帧序号为“11”。北斗网络设备200可以将这4个SLC PDU按照帧序号从小到大顺序，拼接成第3个SLC SDU，上报给MDCP层，作为MDCP层的MDCP PDU2。北斗网络设备200可以将MDCP PDU2存入MDCP层接收缓冲区(MDCP Rxbuffer)中。其中，MDCP PDU2中后继指示字段的值为“11”。
上述示例仅仅用于解释本申请，不应构成限定。
4、北斗网络设备200在MDCP层对接收数据的协议解析过程。
在MDCP层，北斗网络设备200可以在接收到终端100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。
当北斗网络设备200从SLC层获取到后继指示字段的值为“11”的MDCP PDU后，北斗网络设备200可以从MDCP Rxbuffer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，并在拼接之后去除冗余指示字段和padding数据，得到MDCP SDU。北斗网络设备200可以将MDCP SDU通过层间接口上报给应用层，作为应用层报文。
下面介绍本申请实施例中提供的北斗通信系统10中数据入站时SLC层的接收确认机制。
图7示出了本申请实施例中提供的一种数据入站时SLC层的接收确认机制。
如图7所示，北斗通信系统10在SLC层的通信交互过程可以如下：
1、终端100可以按照帧序号从小到大的顺序等间隔发送SLC SDU中的N个SLC PDU。其中，N≤M，M为SLC SDU的最大分段数。在本申请实施例中，以M值取4进行示例性说明。
2、北斗网络设备200在接收到首个SLC PDU后，在t0时刻启动SLC层接收会话(session)，计算SLC PDU接收窗的剩余时间长度(tStationRevwindow)，并在SLC PDU接收窗结束后反馈ACK给终端100。其中，该ACK的数据部分占用N个bit，用于表示北斗网络设备200已接收到的SLC PDU的帧序号。该ACK的数据部分的第i个bit位可以用于表示北斗网络设备200是否已接收到SLC SDU中的第i个SLC PDU，其中，i≤N。
3、终端100在发送完N个SLC PDU后，切换射频硬件从发送(Tx)态切换至接收(Rx)态，在ACK接收窗内接收北斗网络设备200反馈的ACK。
接下来介绍上述图7中示出的参数及其含义。
(1)tStationProcess：指北斗网络设备200上的信号处理调度时延。其中，由于tStationProcess是动态的，需要确保最大时延固定。经试验数据的，tStationProcess的最小值(t_MinStatProc)可以为1s，tStationProcess的最大值(t_MaxStatProc)可以为4s。
(2)tPropagate：指终端100与北斗网络设备200的空口传播时延。其中，经实验数据测得，tPropagate的典型值可以为270ms。
(3)tUeRevAckWindow：指终端100接收ACK的持续时间窗长度。
(4)tUeStartRcvAck：指终端100接收ACK的起始时刻。
(5)tUeEndRcvAck：指终端100接收ACK的停止时刻。
(6)tTx2RxSwitch：指终端100从发送状态到接收状态的切换时长。其中，经实验数据测得，tTx2RxSwitch的典型值可以为600ms。
(7)δ：指北斗网络设备200上出站物理帧的发送时间对齐偏差。北斗网络设备200在完成信号处理和调度时不一定刚好在出站物理帧发送时刻，需要等待下一个出站物理帧的发送时刻时才能发送物理帧。其中，0≤δ≤125ms。
(8)tUeUlFrameLen：指终端100发送的SLC PDU的时间长度。其中，128ms≤tUeUlFrameLen≤512ms。
(9)nUeTotalFrameNum：指终端100将SLC SDU分段的总帧数，即，一个SLC SDU中包括SLC PDU的总帧数。
(10)tUeTxInterval：指终端100发送SLC PDU的时间间隔。SLC PDU的发送间隔(tUeTxInterval)可以指相邻两个SLC PDU中前一个SLC PDU的发送结束时刻与后一个SLC PDU的发送起始时刻之间的时间间隔。tUeTxInterval为预设值，其中，示例性的，tUeTxInterval的典型值可以为2s。
(11)tStationRevWindow：指北斗网络设备200上SLC PDU接收时间窗的剩余时间长度，简称，SLC PDU接收窗的剩余时间长度。
(12)tStationSendAck：指北斗网络设备200向终端100发送ACK的时间。
(13)nStationRevFrameSN：指北斗网络设备200当前接收到SLC PDU的帧序号。其中，由于在本申请实施例中，SLC SDU最多可以包括4帧SLC PDU，因此，0≤nStationRevFrameSN≤3，nStationRevFrameSN为整数。
(14)tUeTxEnd：指终端100发送完SLC SDU中最后一个SLC PDU的时刻，作为接收ACK时间的参考点。
(15)tStationDlFrameLen：指北斗网络设备200发送的物理帧的时间长度。其中，本申请实施例中tStationDlFrameLen的值为固定值，例如，tStationDlFrameLen的值可以取125ms。
接下来，具体介绍本申请实施例中北斗网络设备200如何确定出SLC PDU接收窗的剩余时间长度，终端100如何确定出ACK接收窗的启动时刻以及ACK窗结束时刻。
1、北斗网络设备200可以基于接收到最近一个SLC PDU的帧序号、当前SLC SDU会话中SLC PDU的帧总数、北斗网络设备200接收到最近一个SLC PDU的接收时刻。终端100发送的SLC PDU的时间间隔和终端100发送的物理帧的时间长度(即、入站物理帧的帧长)，确定出北斗网络设备200上SLC PDU接收窗的剩余时间长度。
其中，北斗网络设备200可以通过如下公式(1)确定出SLC PDU接收窗的剩余时间长度：
tStationRevWindow＝tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen)公式(1)
其中，在上述公式(1)中，tStationRevWindow为北斗网络设备200上SLC PDU接收窗的剩余时间长度。nUeTotalFrameNum为当前SLC SDU会话中SLC PDU的帧总数。nRevFrameSN为北斗网络设备200接收到最近一个SLC PDU的帧序号。tStatRevRctSP为北斗网络设备200接收到最近一个SLC PDU的接收时刻。tUeTxInterval为终端100发送SLC PDU的时间间隔。tUeUlFrameLen为终端100发送的物理帧的时间长度。该tUeTxInterval的值预设在终端100和北斗网络设备200上。上述nRevFrameSN＝{0，1，…，nUeTotalFrameNum-1}。
2、北斗网络设备200可以基于接收到最近一个SLC PDU的接收时刻，SLC PDU接收窗的剩余时间长度、北斗网络设备200的信号处理调度时延，确定出发送ACK的时间点。
其中，北斗网络设备200可以通过如下公式(2)确定出发送ACK的时间点：
tStationSendAck＝tStationRevWindow+tStationProcess+δ公式(2)
其中，在上述公式(2)中，tStationSendAck为北斗网络设备200发送ACK的时间点。tStationRevWindow为北斗网络设备200上SLC PDU接收窗的剩余时间长度。tStationProcess为北斗网络设备200上的信号处理调度时延。δ为北斗网络设备200上出站物理帧的发送时间对齐偏差。tStationAckLen为北斗网络设备200发送的ACK的时间长度。tStationAckLen的值可以为125ms。
3、终端100可以基于终端100发送完SLC SDU中最后一个SLC PDU的时刻、终端100从发送(Tx)态至接收(Rx)态的切换时长、空口传播时延、北斗网络设备200上的信号处理调度时延，确定出终端100接收ACK的起始时刻。
其中，终端100可以通过如下公式(3)确定出接收ACK的起始时刻：
tUeTxEnd+tTx2RxSwitch＜tUeStartRcvAck＜tUeTxEnd+2*tPropagate+tStationProcess公式(3)
其中，在上述公式(3)中，tUeStartRcvAck为终端100接收ACK的起始时刻。tUeTxEnd为终端100发送完SLC SDU中最后一个SLC PDU的时刻。tTx2RxSwitch为终端100从发送状态到接收状态的切换时长。tPropagate为终端100与北斗网络设备200的空口传播时延。tStationProcess为北斗网络设备200上的信号处理调度时延，tStationProcess可以取最小值t_MinStatProc(例如1秒)。
4、终端100可以基于终端100发送的物理帧的时间长度、终端100与北斗网络设备200的空口传播时延、信号处理调度时延、北斗网络设备200发送的物理帧的时间长度和北斗网络设备200上出站物理帧的发送时间对齐偏差，确定出终端100接收ACK的结束时刻。
其中，终端100可以通过如下公式(4)确定出返回ACK的结束时刻：
tUeEndRcvAck＝tUeTxEnd+tUeUlFrameLen+2*tPropagate+tStationProcess+tStationDlFrameLen+δ公式(4)
其中，在上述公式(4)中，tUeEndRcvAck为终端100接收ACK的结束时刻。tUeUlFrameLen为终端100发送的SLC PDU的时间长度。tPropagate为终端100与北斗网络设备200的空口传播时延。tStationProcess为北斗网络设备200上的信号处理调度时延，tStationProcess可以取最大值t_MaxStatProc(例如4秒)。tStationDlFrameLen为北斗网络设备发送的物理帧的时间长度，tStationDlFrameLen的值可以为125ms。δ为北斗网络设备200上出站物理帧的发送时间对齐偏差，在公式(4)中，δ的值取125ms。
下面介绍本申请实施例中在终端100发送的SLC PDU出现丢失场景下的处理流程。
图8示出了本申请实施例中终端100发送的SLC PDU出现丢失时的处理流程。
如图8所示，在SLC PDU出现丢包时的处理流程可以如下：
1、在SLC SDU初传会话(session)中，终端100可以按照帧序号从小到大的顺序等间隔发送SLC SDU中的N个SLC PDU。其中，1≤N≤M，M为SLC SDU的最大分段数。在本申请实施例中，以M值取4进行示例性说明。
其中，这N个SLC PDU中第x号SLC PDU在传输的过程中有丢失，0≤x≤N-1。
2、北斗网络设备200在接收到终端100发送SLC PDU后，可以基于上述公式(1)确定出SLC PDU接收窗的剩余时间长度(tStatRevwindow)。北斗网络设备200可以通过上述公式(2)确定出返回ACK给终端100的时间点。
3、由于第x号SLC PDU有丢失，北斗网络设备200可以在该返回ACK给终端100的时间点发送ACK-1给终端100。其中，由于第x号SLC PDU丢失，该ACK-1可用于指示北斗网络设备200未接收到第x号SLC PDU。
4、终端100可以基于上述公式(3)和公式(4)，确定出ACK接收窗的起始时间和结束时间。
5、终端100可以在ACK接收窗内接收北斗网络设备200发送的ACK-1。
6、在接收到ACK-1后，终端100可以确定出北斗网络设备200未接收到第x号SLC PDU。终端100可以在ACK接收窗结束后，切换接收状态至发送状态，启动SLC SDU重传会话(session)，重传第x号SLC PDU。其中，SLC SDU重传会话中第x号SLC PDU的SAI值与SLC SDU初传会话中第x号SLC PDU的SAI值相同，SLC SDU初传会话中所有SLC PDU的SAI值都相同。
7、北斗网络设备200可以在接收到第x号SLC PDU后，确定出第x号SLC PDU中SAI值与上一个SLC SDU会话(即，SLC SDU初传会话)中SLC PDU的SAI值相同，因此，北斗网络设备200确定出当前接收到的第x号SLC PDU为重传SLC PDU。
8、北斗网络设备200可以通过上述公式(1)确定出SLC PDU接收窗的剩余时间长度(tStatRevwindow)。北斗网络设备200可以通过上述公式(2)确定出返回ACK给终端100的时间点。
9、北斗网络设备200可以在该返回ACK给终端100的时间点发送ACK-2给终端100。其中，该ACK-2可用于指示北斗网络设备200已接收到该SLC SDU中所有的SLC PDU。
10、北斗网络设备200在接收到终端100重传的第x号SLC PDU后，可以将SLC SDU初传会话中收到的SLC PDU与SLC SDU重传会话中收到的第x号SLC PDU，按照帧序号拼接成一个SLC SDU。
11、北斗网络设备200可以将拼接完的SLC SDU从SLC层通过层间接口上报给MDCP层，进行MDCP层的处理。其中，针对MDCP层的处理过程可以参考前述图6所示实施例，在此不再赘述。
12、在SLC SDU重传会话中，终端100可以将重新发送第x号SLC PDU的结束时刻作为SLC SDU重传会话中发送完最后一个SLC PDU的时刻，通过上述公式(3)和公式(4)，确定出ACK接收窗的起始时间和结束时间。
13、终端100可以在ACK接收窗内接收北斗网络设备200发送的ACK-2。在接收到ACK-2后，终端100可以确定出北斗网络设备200已接收到重传的第x号SLC PDU，即，北斗网络设备200已收齐当前SLC SDU中所有的SLC PDU。
14、终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，按照帧序号从小到大的顺序等间隔初传下一个SLC SDU中的所有SLC PDU。
示例性的，在SLC SDU初传会话中，终端100可以等间隔发送4个SLC PDU给北斗网络设备200。其中，北斗网络设备200只接收到了第1、2和3号SLC PDU。北斗网络设备200根据已接收到SLC PDU中的帧总数和帧序号，确定出第0号SLC PDU有丢失。因此，北斗网络设备200可以在返回ACK的时间点返回ACK-1，其中，该ACK-1的数据部分占用4bit，该ACK-1的数据部分的值可以为“0111”，该值“0111”表示北斗网络设备200未接收到第0号SLC PDU，已接收到第1、2和3号SLC PDU。终端100在接收到ACK-1后，可以在SLC SDU重传会话中，单独重传第0号SLC PDU给北斗网络设备200。北斗网络设备200在接收到重传的第0号SLC PDU后，可以在返回ACK给终端100的时间点发送ACK-2给终端100。其中，该ACK-2的数据部分占用4bit，该ACK-2的数据部分的值可以为“1111”，该值“1111”表示北斗网络设备200已收齐第0、1、2和3号SLC PDU。北斗网络设备200可以将接收到的第0号SLC PDU和已接收到的第1、2、和3号SLC PDU，按照帧序号拼接成一个SLC SDU上报给MDCP层。终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，初传下一个SLC SDU中的所有SLC PDU。
上述示例仅仅用于解释本申请，不应构成限定。
需要说明的是，在SLC SDU中N个SLC PDU的传输过程中，不仅限于只丢失一个SLC PDU，还存在丢失多个SLC PDU甚至N个SLC PDU全部丢失的可能。
示例性的，在SLC SDU初传会话中，终端100可以等间隔发送4个SLC PDU给北斗网络设备200。其中，北斗网络设备200只接收到了第1号SLC PDU和第3号SLC PDU。北 斗网络设备200根据已接收到SLC PDU中的帧总数和帧序号，确定出第0号SLC PDU和第2号SLC PDU有丢失。北斗网络设备200可以在返回ACK的时间点返回ACK-1，其中，该ACK-1的数据部分占用4bit，该ACK-1的数据部分的值可以为“0101”，该值“0101”表示北斗网络设备200未接收到第0号SLC PDU和第2号SLC PDU，已接收到第1号SLC PDU和3号SLC PDU。终端100在接收到ACK-1后，可以在SLC SDU重传会话中，单独重传第0号SLC PDU和第2号SLC PDU给北斗网络设备200。北斗网络设备200在接收到重传的第0号SLC PDU和第2号SLC PDU后，可以在返回ACK给终端100的时间点发送ACK-2给终端100，其中，该ACK-2的数据部分占用4bit，该ACK-2的数据部分的值可以为“1111”，该值“1111”表示北斗网络设备200已收齐第0、1、2和3号SLC PDU。终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，初传下一个SLC SDU中的所有SLC PDU。
又示例性的，在SLC SDU初传会话中，终端100可以等间隔发送4个SLC PDU给北斗网络设备200。其中，这4个SLC PDU全部丢失。由于北斗网络设备200未接收到这4个SLC PDU，并不知道终端100是否发送了SLC PDU，因此，北斗网络设备200并不会返回ACK给终端100。终端100在ACK接收窗内未接收到北斗网络设备200的ACK，切换接收状态至发送状态，启动SLC SDU重传会话，重传这4个SLC PDU。北斗网络设备200在接收到这4个SLC PDU后，可以在ACK发送时间点返回ACK-2给终端100。终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，初传下一个SLC SDU中的所有SLC PDU。
上述示例仅仅用于解释本申请，不应构成限定。
在一种可能的实现方式中，终端100重传的SLC PDU，依然可能存在丢失。因此，若终端100在重传第x号SLC PDU给北斗网络设备200后，仍然未接收到北斗网络设备200返回的用于指示第x号SLC PDU已接收到的ACK。终端100可以继续重传该第x号SLC PDU。
其中，考虑到无线传输资源，终端100不能无限制重传一个SLC SDU中的SLC PDU。终端100重传一个SLC SDU中的SLC PDU应受限于最大重传次数(MaxReTxNum)。其中，终端100和北斗网络设备200都可以存储该最大重传次数(MaxReTxNum)。
北斗网络设备200在接收到SLC SDU初传会话中的多个SLC PDU，但未收齐SLC SDU PDU之后，可以基于最大重传次数(MaxReTxNum)和单个SLC SDU会话的时间长度，确定出SLC SDU最大传输时间。
在SLC SDU最大传输时间结束时，北斗网络设备200可以认为终端100不再发送重传SLC PDU给北斗网络设备200，因此，北斗网络设备200可以丢弃该SLC SDU初传会话中未收齐的多个SLC PDU，并结束与终端100的SLC层会话。其中，北斗网络设备200在结束与终端100的SLC层会话(SLC session)后，若MDCP层未接收到整个应用层报文传输过程中的最后一个MDCP PDU，则北斗网络设备200可以丢弃已经接收到的MDCP PDU。
北斗网络设备200在结束与终端100的SLC层会话(SLC session)后，若接收到终端100发送的SLC PDU，则开始一个新的SLC层会话。
在一种可能的实现方式中，终端100在整个应用层报文的传输过程中，可以将SLC层传输的第1个SLC SDU中所有SLC PDU的SAI值设为“0”。在传输第2个SLC SDU时，翻转第2个SLC SDU中所有SLC PDU的SAI值为“1”。在传输第3个SLC SDU时，再次翻转第3个SLC SDU中所有SLC PDU的SAI值为“0”，等等。由于北斗网络设备200在应用层报文传输过程的SLC层会话中，不可能在没有接收到SLC PDU的情况下，反馈ACK给 终端100。因此，北斗网络设备200在应用层报文传输过程的SLC层会话中，接收到的第1个SLC PDU的SAI值不应该为“1”。若北斗网络设备200在应用层报文传输过程的SLC层会话中，接收到第1个SLC PDU的SAI值为“1”，则北斗网络设备200直接丢弃该SLC PDU。
下面介绍本申请实施例中在北斗网络设备200返回的ACK出现丢失场景下的处理流程。
图9示出了本申请实施例中在北斗网络设备200返回的ACK出现丢失时的处理流程。
如图9所示，在ACK出现丢包时的处理流程可以如下：
1、在SLC SDU初传会话(session)中，终端100可以按照帧序号从小到大的顺序等间隔发送SLC SDU中的N个SLC PDU。其中，1≤N≤M，M为SLC SDU的最大分段数。在本申请实施例中，以M值取4进行示例性说明。
2、北斗网络设备200在接收到终端100发送SLC PDU后，北斗网络设备200可以基于上述公式(1)确定出SLC PDU接收窗的剩余时间长度(tStatRevwindow)。北斗网络设备200可以通过上述公式(2)确定出返回ACK给终端100的时间点。
3、由于北斗网络设备200接收到了该SLC SDU中的N个SLC PDU后，在该返回ACK给终端100的时间点发送ACK-2给终端100。
4、北斗网络设备200在接收到终端100初传的N个SLC PDU后，可以将这N个SLC PDU按照帧序号拼接成一个SLC SDU。
5、北斗网络设备200可以将拼接完的SLC SDU从SLC层通过层间接口上报给MDCP层，进行MDCP层的处理。其中，针对MDCP层的处理过程可以参考前述图6所示实施例，在此不再赘述。
6、终端100可以基于上述公式(3)和公式(4)，确定出ACK接收窗的起始时间和结束时间。
7、由于ACK-2有丢失，终端100在ACK接收窗内未接收到北斗网络设备200发送的任何ACK，终端100无法确定北斗网络设备200是否有接收到终端100发送的N个SLC PDU。因此，终端100可以在ACK接收窗结束后，切换接收状态至发送状态，启动SLC SDU重传会话(session)，重传这N个SLC PDU。
其中，SLC SDU重传会话中这N个SLC PDU的SAI值与SLC SDU初传会话中这N个SLC PDU的SAI值相同。
8、北斗网络设备200在接收到终端100重传的N个SLC PDU后，可以解析出这重传的N个SLC PDU的SAI值与已接收到的N个SLC PDU的SAI值相同。因此，北斗网络设备200可以确定出终端100未接收到已发送的ACK-2。
其中，北斗网络设备200可以通过上述公式(1)确定出SLC PDU接收窗的剩余时间长度(tStatRevwindow)。北斗网络设备200可以通过上述公式(2)确定出返回ACK给终端100的时间点。
9、北斗网络设备200可以丢弃终端100重传的N个SLC PDU，并在返回ACK给终端100的时间点重新发送ACK-2给终端100。
10、在SLC SDU重传会话中，终端100可以通过上述公式(3)和公式(4)，确定出ACK接收窗的起始时间和结束时间。
11、在SLC SDU重传会话中，终端100可以在ACK接收窗内接收北斗网络设备200发送的ACK-2。在接收到ACK-2后，终端100可以确定出北斗网络设备200已接收到重传的N个SLC PDU。
示例性的，在SLC SDU初传会话中，终端100可以等间隔发送4个SLC PDU给北斗网络设备200。其中，北斗网络设备200接收到了这初传的4个SLC PDU。北斗网络设备200可以将接收到这初传的4个SLC PDU，按照帧序号拼接成一个SLC SDU上报给MDCP层。北斗网络设备200可以在返回ACK的时间点返回ACK-2，其中，该ACK-2的数据部分占用4bit，该ACK-2的数据部分的值可以为“1111”，该值“1111”表示北斗网络设备200已收齐这4个SLC PDU。由于ACK-2有丢失，终端100在SLC SDU初传会话中的ACK接收窗口内未接收到任何北斗网络设备200返回的ACK。终端100可以开启SLC SDU重传会话，重传这4个SLC PDU给北斗网络设备200。北斗网络设备200在接收到重传的这4个SLC PDU后，可以在返回ACK给终端100的时间点发送ACK-2给终端100，并丢弃这重传的4个SLC PDU。终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，初传下一个SLC SDU中的所有SLC PDU。
上述示例仅仅用于解释本申请，不应构成限定。
在一种可能的实现方式中，终端100重传了一个SLC SDU中的N个SLC PDU给北斗网络设备200。北斗网络设备200返回的ACK-2可能依然存在丢失。因此，当终端100重传了一个SLC SDU中的N个SLC PDU给北斗网络设备200后，若在SLC SDU重传会话的ACK接收窗内未接收到北斗网络设备200反馈的任何ACK，终端100可以继续开启SLC SDU重传会话，重传这SLC SDU中的N个SLC PDU。
其中，考虑到无线传输资源，终端100不能无限制重传一个SLC SDU中的SLC PDU。终端100重传一个SLC SDU中的SLC PDU应受限于最大重传次数(MaxReTxNum)。其中，终端100和北斗网络设备200都可以存储该最大重传次数(MaxReTxNum)。
终端100可以基于最大重传次数(MaxReTxNum)和单个SLC SDU会话的时间长度，确定出SLC SDU最大传输时间。在SLC SDU最大传输时间结束时，终端100不再发送重传SLC PDU给北斗网络设备200，也可以不再初传下一个SLC PDU，提前结束应用层报文的传输。
北斗网络设备200可以基于最大重传次数(MaxReTxNum)和单个SLC SDU会话的时间长度，确定出SLC SDU最大传输时间。若北斗网络设备200在SLC SDU最大传输时间结束时，在MDCP层未接收到MDCP SDU的最后一个MDCP PDU，则北斗网络设备200可以将已接收到终端100发送的MDCP PDU丢弃。
下面介绍本申请实施例中数据入站时SLC PDU和ACK同时出现丢失场景下的处理流程。
图10示出了本申请实施例中数据入站时SLC PDU和ACK同时出现丢失时的处理流程。
如图10所示，数据入站时SLC PDU和ACK同时出现丢失时的处理流程可以如下：
1、在SLC SDU初传会话(session)中，终端100可以按照帧序号从小到大的顺序等间隔发送SLC SDU中的N个SLC PDU。其中，1≤N≤M，M为SLC SDU的最大分段数。在本申请实施例中，以M值取4进行示例性说明。
其中，这N个SLC PDU中第x号SLC PDU在传输的过程中有丢失，0≤x≤N-1。
2、北斗网络设备200在接收到终端100发送SLC PDU后，可以基于上述公式(1)确定出SLC PDU接收窗的剩余时间长度(tStatRevwindow)。北斗网络设备200可以通过上述公式(2)确定出返回ACK给终端100的时间点。
3、由于第x号SLC PDU有丢失，北斗网络设备200可以在该返回ACK给终端100的时间点发送ACK-1给终端100。其中，由于第x号SLC PDU丢失，该ACK-1可用于指示北 斗网络设备200未接收到第x号SLC PDU。
4、终端100可以基于上述公式(3)和公式(4)，确定出ACK接收窗的起始时间和结束时间。
5、由于ACK-1有丢失，终端100在ACK接收窗内未接收到北斗网络设备200发送的任何ACK，终端100无法确定北斗网络设备200是否有接收到终端100发送的N个SLC PDU。因此，终端100可以在ACK接收窗结束后，切换接收状态至发送状态，启动SLC SDU重传会话(session)，重传这N个SLC PDU。
其中，SLC SDU重传会话中这N个SLC PDU的SAI值与SLC SDU初传会话中这N个SLC PDU的SAI值相同。
6、北斗网络设备200在接收到终端100重传的N个SLC PDU后，可以解析出这重传的N个SLC PDU的SAI值与已接收到的(N-n)个SLC PDU的SAI值相同，n为SLC SDU中丢失SLC PDU的个数。因此，北斗网络设备200可以确定出终端100未接收到已发送的ACK-1。
7、北斗网络设备200可以从重传的N个SLC PDU中取出在SLC SDU初传会话中丢失的n个SLC PDU，与SLC SDU初传会话中的(N-n)个SLC PDU，拼接成一个SLC SDU。
8、北斗网络设备200可以将拼接完的SLC SDU从SLC层通过层间接口上报给MDCP层，进行MDCP层的处理。其中，针对MDCP层的处理过程可以参考前述图6所示实施例，在此不再赘述。
9、北斗网络设备200可以通过上述公式(1)确定出SLC PDU接收窗的剩余时间长度(tStatRevwindow)。北斗网络设备200可以通过上述公式(2)确定出返回ACK给终端100的时间点。
10、在北斗网络设备200确认已收齐该SLC SDU中的所有SLC PDU时，北斗网络设备200可以在该返回ACK给终端100的时间点发送ACK-2给终端100。其中，该ACK-2可用于指示北斗网络设备200已接收到该SLC SDU中所有的SLC PDU。
11、在SLC SDU重传会话中，终端100可以通过上述公式(3)和公式(4)，确定出ACK接收窗的起始时间和结束时间。
12、终端100可以在ACK接收窗内接收北斗网络设备200发送的ACK-2。在接收到ACK-2后，终端100可以确定出北斗网络设备200已接收到当前SLC SDU中的所有SLC PDU。
13、终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，按照帧序号从小到大的顺序等间隔初传下一个SLC SDU中的所有SLC PDU。
示例性的，在SLC SDU初传会话中，终端100可以等间隔发送4个SLC PDU给北斗网络设备200。其中，北斗网络设备200只接收到了第1、2和3号SLC PDU。北斗网络设备200根据已接收到SLC PDU中的帧总数和帧序号，确定出第0号SLC PDU有丢失。因此，北斗网络设备200可以在返回ACK的时间点向终端100发送ACK-1，其中，该ACK-1的数据部分占用4bit，该ACK-1的数据部分的值可以为“0111”，该值“0111”表示北斗网络设备200未接收到第0号SLC PDU，已接收到第1、2和3号SLC PDU。由于ACK-1丢失，终端100在SLC SDU初传会话中的ACK接收窗口内未接收到北斗网络设备200返回的任何ACK。终端100可以开启SLC SDU重传会话，重传这4个SLC PDU给北斗网络设备200。北斗网络设备200在接收到重传的这4个SLC PDU后，可以在返回ACK给终端100的时间点发送ACK-2给终端100。其中，该ACK-2的数据部分占用4bit，该ACK-2的数据部分的值可以为“1111”，该值“1111”表示北斗网络设备200已收齐这4个SLC PDU。北斗网络设备200可以从接收到的重传的4个SLC PDU中取出第0号SLC PDU与在SLC SDU初传会话中接 收到的第1、2和3号SLC PDU拼接成一个SLC SDU上报给MDCP层。终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，初传下一个SLC SDU中的所有SLC PDU。
上述示例仅仅用于解释本申请，不应构成限定。
在一种可能的实现方式中，终端100在初传了一个SLC SDU的N个SLC PDU给北斗网络设备200。其中，这初传的N个SLC PDU中有n1个SLC PDU有丢失，北斗网络设备200只接收到了(N-n1)个初传的SLC PDU，其中，1≤n1＜N。北斗网络设备200可以返回ACK给终端100，其中，ACK用于指示北斗网络设备200已接收到SLC PDU的帧序号。其中，ACK有丢失，终端100重传了该SLC SDU中的N个SLC PDU给北斗网络设备200。这时，重传的N个SLC PDU中有n2个SLC PDU有丢失，北斗网络设备200只接收到了(N-n2)个重传的SLC PDU，其中，1≤n2＜N。北斗网络设备200可以通过接收到(N-n2)个重传的SLC PDU对接收到的(N-n1)个初传的SLC PDU进行合并。若合并之后SLC SDU中的SLC PDU仍有缺失，北斗网络设备200可以继续返回ACK给终端100，指示终端100重传缺失的SLC PDU。若合并之后SLC SDU中的SLC PDU已齐全，北斗网络设备200可以这齐全的N个SLC PDU拼接成一个SLC SDU上报给MDCP层。
示例性的，在SLC SDU初传会话中，终端100可以等间隔发送4个SLC PDU给北斗网络设备200。其中，北斗网络设备200只接收到了第2号和第3号SLC PDU。北斗网络设备200根据已接收到SLC PDU中的帧总数和帧序号，确定出第0号和第1号SLC PDU有丢失。因此，北斗网络设备200可以在返回ACK的时间点向终端100发送ACK-3，其中，该ACK-1的数据部分占用4bit，该ACK-3的数据部分的值可以为“0011”，该值“0011”表示北斗网络设备200未接收到第0号SLC PDU，已接收到第1、2和3号SLC PDU。由于ACK-3丢失，终端100在SLC SDU初传会话中的ACK接收窗口内未接收到北斗网络设备200返回的任何ACK。终端100可以开启第一次SLC SDU重传会话，重传这4个SLC PDU给北斗网络设备200。其中，第一次重传的第0号SLC PDU有丢失，北斗网络设备200只接收到第一次重传的第1号、第2号和第3号SLC PDU。北斗网络设备200可以取出接收到第一次重传的第1号与接收到初传的第2号和第3号SLC PDU合并，得到SLC PDU的第1号、第2号、第3号SLC PDU，缺失第0号SLC PDU。北斗网络设备200可以在返回ACK的时间点向终端100发送ACK-1，其中，该ACK-1的数据部分的值可以为“0111”，该值“0111”表示北斗网络设备200未接收到第0号SLC PDU，已接收到第1、2和3号SLC PDU。终端100在接收到ACK-1后，可以开启第二次SLC SDU重传会话，重传第0号SLC PDU给北斗网络设备200。北斗网络设备200在接收到第0号SLC PDU后，可以将第0号SLC PDU与已接收到的第1号SLC PDU、第2号SLC PDU和第3号SLC PDU，按照帧序号拼接成一个SLC SDU上报给MDCP层。北斗网络设备200在收齐SLC SDU的所有SLC PDU后，可以向终端100发送ACK-2。其中，该ACK-2的数据部分占用4bit，该ACK-2的数据部分的值可以为“1111”，该值“1111”表示北斗网络设备200已收齐这4个SLC PDU。终端100在接收到ACK-2后，可以进入下一个SLC SDU发送会话，初传下一个SLC SDU中的所有SLC PDU。
上述示例仅仅用于解释本申请，不应构成限定。
下面介绍本申请实施例中提供的一种北斗通信系统中入站传输控制方法。
图11示出了本申请实施例中提供的一种北斗通信系统中入站传输控制方法的流程示意图。
如图11所示，该北斗通信系统中入站传输控制方法包括如下步骤：
S1101、终端100向北斗网络设备200发送第一SLC SDU中的N个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SAI字段、帧总数字段和帧序号字段。其中，该SAI字段用于指示第一SLC PDU是否为重传数据，帧总数字段用于指示第一SLC SDU中包括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中的序号。
具体有关SAI字段、帧总数字段和帧序号字段的描述，可以参考前述实施例，在此不再赘述。
S1102、北斗网络设备200接收到终端100发送的第一SLC SDU中的M个SLC PDU。
S1103、当M小于N时，北斗网络设备200发送第一ACK给终端100。
其中，该第一ACK用于指示第一SLC SDU中北斗网络设备未接收到SLC PDU的帧序号。其中，第一ACK可以采用位图(Bitmap)的形式，第一ACK的数据部分的前Nbit中每1bit都用于指示第一SLC SDU中一个SLC PDU的接收情况。具体有关，北斗网络设备200的反馈ACK的描述可以参考前述实施例，在此不再赘述。
S1104、终端100基于第一ACK，确定第一SLC SDU中北斗网络设备200未接收到的SLC PDU。
具体有关终端100如何基于北斗网络设备200反馈的ACK，识别北斗网络设备200未接收到的SLC PDU，可以参考前述实施例，在此不再赘述。
S1105、终端100重传第一SLC SDU中北斗网络设备200未接收到的SLC PDU。
具体涉及终端100，重传SLC PDU的流程可以参考前述图8-图10所示实施例，在此不再赘述。
下面介绍终端100执行的一些可能的实现方式。
在一种可能的实现方式中，在终端100发送第一SLC SDU中的N个SLC PDU给北斗网络设备200后，该方法还包括：当终端100接收到北斗网络设备200发送的第二ACK时，终端发送第二SLC SDU中的一个或多个SLC PDU给北斗网络设备200，第二ACK用于指示北斗网络设备已接收到第一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。
这样，在北斗网络设备200收齐终端100发送的一个SLC SDU中的所有SLC PDU后，终端发送下一个SLC SDU中的所有SLC PDU给北斗网络设备200，以保持数据的持续传输。
在一种可能的实现方式中，第一SLC SDU中SLC PDU的SAI字段的值与第二SLC SDU中SLC PDU的SAI字段的值不同。
具体的，SAI字段的功能作用，可以参考前述实施例，在此不再赘述。
这样，通过SLC PDU的SAI字段的值翻转与否，来表示SLC PDU是否是重传数据，可以保证北斗网络设备200识别出接收到的SLC PDU是否是重传数据，保证了北斗通信系统中的数据持续传输。
在一种可能的实现方式中，在终端100发送第一SLC SDU中的N个SLC PDU给北斗网络设备200后，该方法还包括：当终端100在发送第一SLC SDU中的N个SLC PDU给北斗 网络设备200之后的ACK接收时间窗内，未接收到北斗网络设备200发送的ACK时，终端100重传第一SLC SDU中的N个SLC PDU给北斗网络设备200。
具体内容，可以参考前述图9所示实施例，在此不再赘述。
在一种可能的实现方式中，在所述终端发送所述第一SLC SDU中的N个SLC PDU给北斗网络设备之前，该方法还包括：终端100在SLC层获取到终端100的MDCP层下发的多个SLC SDU，其中，所述多个SLC SDU中包括第一SLC SDU和第二SLC SDU；终端100在SLC层将第一SLC SDU拆分成N个SLC PDU。
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，在终端100在SLC层获取到终端的MDCP层下发的多个SLC SDU之前，该方法还包括：终端100在MDCP层获取到终端100的应用层下发的应用层报文；终端100在MDCP层将应用层报文作为MDCP SDU，并在MDCP SDU加入填充数据和冗余长度指示字段后，拆分成多个MDCP PDU；其中，冗余长度指示字段用于指示填充数据的数据长度，该多个MDCP PDU中包括第一MDCP PDU，该第一MDCP PDU的包头信息包括后继指示字段，该后继指示字段用于指示第一MDCP PDU在该多个MDCP PDU中的顺序；终端100将多个MDCP PDU从MDCP层下发至SLC层，作为SLC层的多个SLC SDU。
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，在终端100在MDCP层获取到终端100的应用层下发的应用层报文之前，该方法还包括：终端100获取原始数据；终端100在应用层将原始数据，进行压缩得到压缩数据；终端100在应用层将压缩数据进行加密得到加密后数据；终端100在加密后数据头部加上报文头信息，得到所述应用层报文；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压缩算法，加密指示字段用于指示对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4所示实施例，在此不再赘述。
在一种可能的实现方式中，终端100发送第一SLC SDU中的N个SLC PDU给北斗网络设备，具体包括：终端100将第一SLC PDU从SLC层下发至物理PHY层，作为PHY层的第一编码块；终端100在所述PHY层在第一编码块的尾部添加校验位信息，并对第一编码块和校验位信息进行编码得到第一编码数据；终端100在所述PHY层在所述第一编码数据中插入导频信息，得到第一导频数据；终端100在所述PHY层对第一导频数据和第一导频数据的同步头进行调制，得到第一调制数据和第一调制同步头；终端100在PHY层将第一调制数据和调制同步头进行扩频得到第一扩频调制数据；终端在PHY层将第一扩频调制数据发送给北斗网络设备。
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，终端100基于终端100发送完第一SLC SDU中最后一个SLC PDU的时刻、终端100从发送态至接收态的切换时长、空口传播时延和北斗网络设备200的信号处理调度时延，确定出ACK接收时间窗的起始时刻；
终端100在ACK接收时间窗的起始时刻开始接收北斗网络设备200发送的ACK。
其中，终端100确定出ACK接收时间窗的起始时刻的公式为：
tUeTxEnd+tTx2RxSwitch＜tUeStartRcvAck＜tUeTxEnd+2*tPropagate+tStationProcess
其中，tUeStartRcvAck为ACK接收时间窗的起始时刻；tUeTxEnd为终端100发送完第一SLC SDU中最后一个SLC PDU的时刻；tTx2RxSwitch为终端100从发送态至接收态的切换时长；tPropagate为空口传播时延；tStationProcess为北斗网络设备200上的信号处理调度时延。
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，终端100基于终端100发送的物理帧的时间长度、空口传播时延、北斗网络设备200的信号处理调度时延、北斗网络设备200发送的物理帧的时间长度和北斗网络设备200发送物理帧的时间对齐偏差，确定出ACK接收时间窗的结束时刻；终端100在ACK接收时间窗的结束时刻停止接收北斗网络设备200发送的ACK。
其中，终端100确定出ACK接收时间窗的结束时刻的公式为：
tUeEndRcvAck＝tUeTxEnd+tUeUlFrameLen+2*tPropagate+tStationProcess+tStationDlFrameLen+δ
其中，tUeEndRcvAck为ACK接收时间窗的结束时刻，tUeUlFrameLen为终端100发送的物理帧的时间长度，tPropagate为空口传播时延，tStationProcess为北斗网络设备200的信号处理调度时延，tStationDlFrameLen为北斗网络设备200发送的物理帧的时间长度，δ为北斗网络设备200发送物理帧的时间对齐偏差。
下面介北斗网络设备200执行的一些可能的实现方式。
在一种可能的实现方式中，北斗网络设备200接收到终端100发送的第一SLC SDU中的M个SLC PDU后，当M等于所述N时，北斗网络设备200向终端100发送第二ACK，其中，第二ACK用于指示北斗网络设备已接收到第一SLC SDU中的N个SLC PDU；北斗网络设备200接收到终端100发送的第二SLC SDU中的一个或多个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。
这样，在北斗网络设备200收齐终端100发送的一个SLC SDU中的所有SLC PDU后，终端发送下一个SLC SDU中的所有SLC PDU给北斗网络设备200，以保持数据的持续传输。
在一种可能的实现方式中，第二SLC SDU中SLC PDU的SAI字段的值与第一SLC SDU中SLC PDU的SAI字段的值不同。
具体的，SAI字段的功能作用，可以参考前述实施例，在此不再赘述。
这样，通过SLC PDU的SAI字段的值翻转与否，来表示SLC PDU是否是重传数据，可以保证北斗网络设备200识别出接收到的SLC PDU是否是重传数据，保证了北斗通信系统中的数据持续传输。
在一种可能的实现方式中，北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU，具体包括：北斗网络设备200在PHY层获取到终端100发送的第一扩频调制数据；北斗网络设备200在PHY层对第一扩频调制数据进行解扩频，得到第一调制数据和第一调制同 步头；北斗网络设备200在PHY层对第一调制数据和第一调制同步头解调，得到第一导频数据和第一同步头；北斗网络设备200在PHY层去除第一导频数据中的导频信息，得到第一编码数据；北斗网络设备200在PHY层对第一编码数据进行解码，得到第一编码块和第一校验信息；北斗网络设备200在PHY层基于第一校验信息对第一编码块进行校验，并在校验成功后，将第一编码块作为北斗网络设备200的SLC层中第一SLC SDU中的第一SLC PDU从PHY层呈递给北斗网络设备的SLC层。
具体内容，可以参考前述图5所示实施例，在此不再赘述。
在一种可能的实现方式中，北斗网络设备200接收到终端100发送的第一SLC SDU中的M个SLC PDU之后，该方法还包括：北斗网络设备200在SLC层将M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从北斗网络设备的SLC层上报给北斗网络设备的MDCP层，第一MDCP PDU的包头信息中包括后继指示字段，后继指示字段用于指示第一MDCP PDU在终端100发送的多个MDCP PDU中的顺序。
具体内容，可以参考前述图5所示实施例，在此不再赘述。
在一种可能的实现方式中，该方法还包括：北斗网络设备200在MDCP层获取到从北斗网络设备200的SLC层上报的第二MDCP PDU；
当第二MDCP PDU中的后继指示字段指示第二MDCP PDU为终端100发送的多个MDCP PDU中的最后一个时，北斗网络设备200在MDCP层将第一MDCP PDU与第二MDCP PDU拼接成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5所示实施例，在此不再赘述。
在一种可能的实现方式中，应用层报文包括报文头信息和加密后数据，报文头信息包括加密指示字段和压缩指示字段，压缩指示字段用于指示终端100将原始数据压缩成压缩数据时使用的压缩算法，加密指示字段用于指示终端100将压缩数据加密成加密后数据时使用的加密算法；
该方法还包括：北斗网络设备200在应用层通过应用层报文中加密指示字段指示的加密算法，对应用层报文中加密后数据进行解密，得到压缩数据；北斗网络设备在应用层通过应用层报文中压缩指示字段指示的压缩算法，对压缩数据进行解压缩，得到原始数据。
具体内容，可以参考前述图5所示实施例，在此不再赘述。
在一种可能的实现方式中，北斗网络设备200基于接收到第一SLC SDU中第一SLC PDU的帧序号、第一SLC SDU中SLC PDU的总数量、第一SLC PDU的接收时刻、终端100发送的物理帧的帧间隔、终端100发送的物理帧的时间长度，确定出SLC PDU接收窗的剩余时间长度。
其中，北斗网络设备200通过如下公式确定出SLC PDU接收窗的剩余时间长度：
tStationRevWindow＝tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen)
其中，tStationRevWindow为SLC PDU接收窗的剩余时间长度，tStatRevRctSP为第一SLC PDU的接收时刻，nUeTotalFrameNum为第一SLC SDU中SLC PDU的总数量，nRevFrameSN为第一SLC PDU的帧序号，tUeTxInterval为终端100发送物理帧的帧间隔。tUeUlFrameLen为终端100发送的物理帧的时间长度。
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，该方法还包括：北斗网络设备200基于SLC PDU接收窗的剩余时间长度和北斗网络设备200的信号处理调度时延，确定出发送ACK的时间点。
其中，北斗网络设备200通过如下公式确定出发送ACK的时间点：
tStationSendAck＝tStationRevWindow+tStationProcess+δ
其中，tStationSendAck为北斗网络设备200发送ACK的时间点，tStationRevWindow为SLC PDU接收窗的剩余时间长度，tStationProcess为北斗网络设备200上的信号处理调度时延，δ为北斗网络设备200上出站物理帧的发送时间对齐偏差。
具体内容，可以参考前述图7所示实施例，在此不再赘述。
通过本申请实施例中提供一种北斗通信系统中入站传输控制方法，终端100可以向北斗网络设备200发送第一SLC PDU的N个SLC PDU。若北斗网络设备200基于已接收到的SLC PDU的帧头信息确定出第一SLC SDU中SLC PDU有缺失，则返回第一ACK给终端，其中，第一ACK用于指示北斗网络设备未接收到第一SLC SDU中SLC PDU的帧序号。终端100在接收到北斗网络设备200的第一ACK后，重传第一SLC SDU中北斗网络设备200未收到的SLC PDU给北斗网络设备200。这样，在终端100发送的数据有丢失时，保证数据传输过程的正常进行。
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12至图15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12，图12是本申请实施例提供的通信装置1200的结构示意图。该通信装置1200可以为上述实施例中的终端100。可选的，通信装置1200可以为一种芯片/芯片系统，例如，北斗通信芯片。如图12所示，该通信装置1200可以包括收发单元1210和处理单元1220。
一种设计中，收发单元1210，可用于向北斗网络设备200发送第一SLC SDU中的N个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SAI字段、帧总数字段和帧序号字段。其中，该SAI字段用于指示第一SLC PDU是否为重传数据，帧总数字段用于指示第一SLC SDU中包括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中的序号。
收发单元1210，还用于接收北斗网络设备200返回的第一ACK。该第一ACK用于指示第一SLC SDU中北斗网络设备未接收到SLC PDU的帧序号。
处理单元1220，可用于基于第一ACK，确定第一SLC SDU中北斗网络设备200未接收到的SLC PDU。
收发单元1210，还用于重传第一SLC SDU中北斗网络设备200未接收到的SLC PDU给北斗网络设备200。
可选的，收发单元1210，还可用于执行上述图11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1220，还可用于执行上述图11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13，图13是本申请实施例提供的通信装置1300的结构示意图。该通信装置1300可以为上述实施例中的北斗网络设备200。可选的，通信装置1300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13所示，该通信装置1300可以包括收发单元1310和处理单元1320。
一种设计中，收发单元1310，可用于接收到终端100发送的第一SLC SDU中的M个SLC PDU，M为正整数；其中，M个SLC PDU包括第一SLC PDU，第一SLC PDU的帧头信息包括SAI字段、帧总数字段和帧序号字段；SAI字段用于指示SLC PDU是否为重传数据，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，帧序号字段用于指示第一SLC PDU在第一SLC SDU中的帧序号。
处理单元1320，可用于基于接收到的M个SLC PDU的帧头信息，生成第一ACK。
收发单元1310，还用于当所述M小于所述N时，向终端100发送第一ACK，其中，第一ACK用于指示第一SLC SDU中未接收到的SLC PDU的帧序号。
可选的，收发单元1310，还可用于执行上述图11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1320，还可用于执行上述图11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1300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12所述的终端100的功能的任何形态的产品，但凡具备上述图13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可以是终端100，或其中的装置。如图14所示，该通信装置1400包括处理器1401和与所述处理器内部连接通信的收发器1402。其中，处理器1401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1402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1402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1400还可以包括天线1403和/或射频单元(图未示意)。所述天线1403和/或射频单元可以位于所述通信装置1400内部，也可以与所述通信装置1400分离，即所述天线1403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1400中可以包括一个或多个存储器1404，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1400上被运行，使得通信装置1400执行上述方法实施例中描述的方法。可选的，所述存储器1404中还可以存储有数据。通信装置1400和存储器1404可以单独设置，也可以集成在一起。
其中，处理器1401、收发器1402、以及存储器1404可以通过通信总线连接。
一种设计中，通信装置1400可以用于执行前述实施例中终端100的功能：处理器1401可以用于执行上述图11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1402可以用于执行上述图11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1401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1401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1401上运行，可使得通信装置1400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1400中，该种情况下，处理器1401可能由硬件实现。
在一种实现方式中，通信装置1400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14的限制。通信装置1400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1400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可以是北斗网络设备200，或其中的装置。如图15所示，该通信装置1500包括处理器1501和与所述处理器内部连接通信的收发器1502。其中，处理器1501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1502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1502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1500还可以包括天线1503和/或射频单元(图未示意)。所述天线1503和/或射频单元可以位于所述通信装置1500内部，也可以与所述通信装置1500分离，即所述天线1503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1500中可以包括一个或多个存储器1504，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1500上被运行，使得通信装置1500执行上述方法实施例中描述的方法。可选的，所述存储器1504中还可以存储有数据。通信装置1500和存储器1504可以单独设置，也可以集成在一起。
其中，处理器1501、收发器1502、以及存储器1504可以通过通信总线连接。
一种设计中，通信装置1500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1501可以用于执行上述图11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1502可以用于执行上述图11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1501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1501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1501上运行，可使得通信装置1500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1500中，该种情况下，处理器1501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，电子设备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 (31)

  1. 一种北斗通信系统中入站传输控制方法，其特征在于，包括：
    终端发送第一卫星链路控制层服务数据单元SLC SDU中的N个卫星链路控制层协议数据单元SLC PDU给北斗网络设备，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的帧头信息包括服务数据单元交替指示SAI字段、帧总数字段和帧序号字段；所述SAI字段用于指示所述第一SLC PDU是否为重传数据，所述帧总数字段用于指示所述第一SLC SDU中包括SLCPDU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；
    当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时，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，其中，所述第一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。
  2. 根据权利要求1所述的方法，其特征在于，在所述终端发送所述第一SLC SDU中的N个SLC PDU给北斗网络设备后，所述方法还包括：
    当所述终端接收到所述北斗网络设备发送的第二ACK时，所述终端发送第二SLC SDU中的一个或多个SLC PDU给所述北斗网络设备，所述第二ACK用于指示所述北斗网络设备已接收到所述第一SLC SDU中的N个SLC PDU。
  3. 根据权利要求2所述的方法，其特征在于，所述第二SLC SDU中SLC PDU的SAI字段的值与所述第一SLC SDU中SLC PDU的SAI字段的值不同。
  4. 根据权利要求1所述的方法，其特征在于，在所述终端发送所述第一SLC SDU中的N个SLC PDU给北斗网络设备后，所述方法还包括：
    当所述终端在发送所述第一SLC SDU中的N个SLC PDU给所述北斗网络设备之后的ACK接收时间窗内，未接收到所述北斗网络设备发送的ACK时，所述终端重传所述第一SLC SDU中的N个SLC PDU给所述北斗网络设备。
  5. 根据权利要求1-4中任一项所述的方法，其特征在于，在所述终端发送所述第一SLC SDU中的N个SLC PDU给北斗网络设备之前，所述方法还包括：
    所述终端在卫星链路控制SLC层获取到所述终端的消息数据汇聚MDCP层下发的多个SLC SDU，其中，所述多个SLC SDU中包括所述第一SLC SDU和第二SLC SDU；
    所述终端在所述SLC层将所述第一SLC SDU拆分成所述N个SLC PDU。
  6. 根据权利要求5所述的方法，其特征在于，在所述终端在SLC层获取到所述终端的MDCP层下发的多个SLC SDU之前，所述方法还包括：
    所述终端在所述MDCP层获取到所述终端的应用层下发的应用层报文；
    所述终端在所述MDCP层将所述应用层报文作为MDCP SDU，并在所述MDCP SDU加入填充数据和冗余长度指示字段后，拆分成多个MDCP PDU；其中，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，所述多个MDCP PDU中包括第一MDCP PDU，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在所述多个MDCP PDU中的顺序；
    所述终端将所述多个MDCP PDU从所述MDCP层下发至所述SLC层，作为所述SLC层的所述多个SLC SDU。
  7. 根据权利要求6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，进行压缩得到压缩数据；
    所述终端在所述应用层将所述压缩数据进行加密得到加密后数据；
    所述终端在所述加密后数据头部加上报文头信息，得到所述应用层报文；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压缩算法，所述加密指示字段用于指示对所述压缩数据加密时使用的加密算法。
  8. 根据权利要求1-7中任一项所述的方法，其特征在于，所述终端发送所述第一SLC SDU中的N个SLC PDU给北斗网络设备，具体包括：
    所述终端将所述第一SLC PDU从SLC层下发至物理PHY层，作为所述PHY层的第一编码块；
    所述终端在所述PHY层在所述第一编码块的尾部添加校验位信息，并对所述第一编码块和所述校验位信息进行编码得到第一编码数据；
    所述终端在所述PHY层在所述第一编码数据中插入导频信息，得到第一导频数据；
    所述终端在所述PHY层对所述第一导频数据和所述第一导频数据的同步头进行调制，得到第一调制数据和第一调制同步头；
    所述终端在所述PHY层将所述第一调制数据和调制同步头进行扩频得到第一扩频调制数据；
    所述终端在所述PHY层将所述第一扩频调制数据发送给所述北斗网络设备。
  9. 根据权利要求1-8中任一项所述的方法，其特征在于，所述方法还包括：
    所述终端基于所述终端发送完所述第一SLC SDU中最后一个SLC PDU的时刻、所述终端从发送态至接收态的切换时长、空口传播时延和所述北斗网络设备的信号处理调度时延，确定出ACK接收时间窗的起始时刻；
    所述终端在所述ACK接收时间窗的起始时刻开始接收所述北斗网络设备发送的ACK。
  10. 根据权利要求9所述的方法，其特征在于，所述终端确定出所述ACK接收时间窗的起始时刻的公式为：
    tUeTxEnd+tTx2RxSwitch＜tUeStartRcvAck＜tUeTxEnd+2*tPropagate+tStationProcess
    其中，tUeStartRcvAck为ACK接收时间窗的起始时刻；tUeTxEnd为所述终端发送完所述第一SLC SDU中最后一个SLC PDU的时刻；tTx2RxSwitch为所述终端从发送态至接收态的切换时长；tPropagate为空口传播时延；tStationProcess为所述北斗网络设备上的信号处理调度时延。
  11. 根据权利要求1-8中任一项所述的方法，其特征在于，所述方法还包括：
    所述终端基于所述终端发送的物理帧的时间长度、空口传播时延、所述北斗网络设备的信号处理调度时延、所述北斗网络设备发送的物理帧的时间长度和所述北斗网络设备发送物理帧的时间对齐偏差，确定出ACK接收时间窗的结束时刻；
    所述终端在所述ACK接收时间窗的结束时刻停止接收所述北斗网络设备发送的ACK。
  12. 根据权利要求11所述的方法，其特征在于，所述终端确定出所述ACK接收时间窗的结束时刻的公式为：
    tUeEndRcvAck＝tUeTxEnd+tUeUlFrameLen+2*tPropagate+tStationProcess+tStationDlFrameLen+δ
    其中，tUeEndRcvAck为所述ACK接收时间窗的结束时刻，tUeUlFrameLen为所述终端发送的物理帧的时间长度，tPropagate为空口传播时延，tStationProcess为所述北斗网络设备的信号处理调度时延，tStationDlFrameLen为所述北斗网络设备发送的物理帧的时间长度，δ为所述北斗网络设备发送物理帧的时间对齐偏差。
  13. 一种北斗通信系统中入站传输控制方法，其特征在于，包括：
    北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU，M为正整数；其中，所述M个SLC PDU包括第一SLC PDU，所述第一SLC PDU的帧头信息包括SAI字段、帧总数字段和帧序号字段；所述SAI字段用于指示所述SLC PDU是否为重传数据，所述帧总数字段用于指示所述第一SLC SDU中包括SLCPDU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M小于所述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用于指示所述第一SLC SDU中所述北斗网络设备未接收到的SLC PDU的帧序号。
  14. 根据权利要求13所述的方法，其特征在于，在所述北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU后，所述方法还包括：
    当所述M等于所述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用于指示所述北斗网络设备已接收到所述第一SLC SDU中的N个SLC PDU；
    所述北斗网络设备接收到所述终端发送的第二SLC SDU中的一个或多个SLC PDU。
  15. 根据权利要求14所述的方法，其特征在于，所述第二SLC SDU中SLC PDU的SAI字段的值与所述第一SLC SDU中SLC PDU的SAI字段的值不同。
  16. 根据权利要求13-15中任一项所述的方法，其特征在于，所述北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU，具体包括：
    所述北斗网络设备在所述PHY层获取到终端发送的第一扩频调制数据；
    所述北斗网络设备在所述PHY层对所述第一扩频调制数据进行解扩频，得到第一调制数据和第一调制同步头；
    所述北斗网络设备在所述PHY层对所述第一调制数据和所述第一调制同步头解调，得到第一导频数据和第一同步头；
    所述北斗网络设备在所述PHY层去除所述第一导频数据中的导频信息，得到第一编码数 据；
    所述北斗网络设备在所述PHY层对所述第一编码数据进行解码，得到第一编码块和第一校验信息；
    所述北斗网络设备在所述PHY层基于所述第一校验信息对所述第一编码块进行校验，并在校验成功后，将所述第一编码块作为所述北斗网络设备的SLC层中所述第一SLC SDU中的所述第一SLC PDU从所述PHY层呈递给所述北斗网络设备的SLC层。
  17. 根据权利要求14中所述的方法，其特征在于，所述北斗网络设备接收到终端发送的第一SLC SDU中的M个SLC PDU之后，所述方法还包括：
    所述北斗网络设备在SLC层将所述M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，所述第一MDCP PDU的包头信息中包括后继指示字段，所述后继指示字段用于指示所述第一MDCP PDU在所述终端发送的多个MDCP PDU中的顺序。
  18. 根据权利要求17所述的方法，其特征在于，所述方法还包括：
    所述北斗网络设备在所述MDCP层获取到从所述北斗网络设备SLC层上报的第二MDCP PDU；
    当所述第二MDCP PDU中的后继指示字段指示所述第二MDCP PDU为所述终端发送的多个MDCP PDU中的最后一个时，所述北斗网络设备在所述MDCP层将所述第一MDCP PDU与所述第二MDCP PDU拼接成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。
  19. 根据权利要求18所述的方法，其特征在于，所述应用层报文包括报文头信息和加密后数据，所述报文头信息包括加密指示字段和压缩指示字段，所述压缩指示字段用于指示所述终端将原始数据压缩成压缩数据时使用的压缩算法，所述加密指示字段用于指示所述终端将所述压缩数据加密成加密后数据时使用的加密算法；
    所述方法还包括：
    所述北斗网络设备在所述应用层通过所述应用层报文中加密指示字段指示的加密算法，对所述应用层报文中所述加密后数据进行解密，得到所述压缩数据；
    所述北斗网络设备在所述应用层通过所述应用层报文中压缩指示字段指示的压缩算法，对所述压缩数据进行解压缩，得到所述原始数据。
  20. 根据权利要求13-19中任一项所述的方法，其特征在于，所述方法还包括：
    所述北斗网络设备基于接收到所述第一SLC SDU中第一SLC PDU的帧序号、所述第一SLC SDU中SLC PDU的总数量、所述第一SLC PDU的接收时刻、所述终端发送的物理帧的帧间隔、所述终端发送的物理帧的时间长度，确定出SLC PDU接收窗的剩余时间长度。
  21. 根据权利要求20中所述的方法，其特征在于，所述北斗网络设备通过如下公式确定出SLC PDU接收窗的剩余时间长度：
    tStationRevWindow＝tStatRevRctSP+(nUeTotalFrameNum-nRevFrameSN-1)*(tUeTxInterval+tUeUlFrameLen)
    其中，tStationRevWindow为SLC PDU接收窗的剩余时间长度，tStatRevRctSP为所述第一SLC PDU的接收时刻，nUeTotalFrameNum为所述第一SLC SDU中SLC PDU的总数量，nRevFrameSN为所述第一SLC PDU的帧序号，tUeTxInterval为所述终端发送物理帧的帧间隔，tUeUlFrameLen为所述终端发送的物理帧的时间长度。
  22. 根据权利要求20或21所述的方法，其特征在于，所述方法还包括：
    所述北斗网络设备基于SLC PDU接收窗的剩余时间长度和所述北斗网络设备的信号处理调度时延，确定出发送ACK的时间点。
  23. 根据权利要求22中所述的方法，其特征在于，所述北斗网络设备通过如下公式确定出发送ACK的时间点：
    tStationSendAck＝tStationRevWindow+tStationProcess+δ
    其中，tStationSendAck为所述北斗网络设备发送ACK的时间点，tStationRevWindow
    为SLC PDU接收窗的剩余时间长度，tStationProcess为所述北斗网络设备上的信号处理调度时延，δ为所述北斗网络设备上出站物理帧的发送时间对齐偏差。
  24. 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，用于发送第一SLC SDU中的N个SLC PDU给北斗网络设备，N为正整数；其中，所述SLC PDU的帧头信息包括SAI字段、帧总数字段和帧序号字段；所述SAI字段用于指示所述SLC PDU是否为重传数据，所述帧总数字段用于指示所述第一SLC SDU中包括SLCPDU的总数量N，所述帧序号字段用于指示所述SLC PDU在所述第一SLC SDU中的序号；
    所述北斗网络设备，用于接收到所述终端发送的所述第一SLC SDU中的M个SLC PDU，M为正整数；
    所述北斗网络设备，还用于当所述M小于所述N时向所述终端发送第一ACK，其中，所述第一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，还用于当接收到所述北斗网络设备发送的所述第一ACK时，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。
  25. 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1-12任一项所述的方法。
  26. 根据权利要求25所述的通信装置，其特征在于，所述通信装置为终端。
  27. 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13-23任一项所述的方法。
  28. 根据权利要求27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。
  29. 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1-12任一项所述的方法。
  30. 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13-23任一项所述的方法。
  31. 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1-12任一项所述的方法。
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