Outbound data transmission method, system and related device in Beidou communication system

Abstract

The application relates to the technical field of satellite communication, and discloses an outbound data transmission method in a Beidou communication system, which can realize that a terminal carries MCS information in an inbound first user frame, sends the MCS information to a Beidou network device, and instructs the Beidou network device to encode and modulate service data sent to the terminal according to the MCS information suggested by the terminal. In this way, the terminal can feed back the outbound MCS to the Beidou network device without additional signaling overhead, and the channel utilization is improved.

Description

Technical Field

[0001] This application relates to the field of satellite communication technology, and in particular to a method, system and related devices for outbound data transmission in a BeiDou communication system. Background Technology

[0002] The BeiDou Navigation Satellite System is a major infrastructure project independently developed by my country, integrating positioning, timing, and communication. One of the distinctive features of BeiDou's short message service is its ability to differentiate it from other global navigation systems such as the US GPS, Russian GLONASS, and European Galileo. BeiDou's short message service is particularly suitable for communication in areas such as oceans, deserts, grasslands, and uninhabited areas where mobile communication is unavailable, lacks coverage, or has been damaged. The BeiDou-3 satellite's short message system has upgraded its technical framework, achieving separation of military and civilian signals. While ensuring full satisfaction of military needs, the government has opened up some necessary resources of the BeiDou short message service communication system to civilian use. Communication protocols need to be designed based on the characteristics of the BeiDou short message service communication system, taking into account the specific needs of civilian services and equipment.

[0003] In wireless communication, varying user locations, communication times, and weather conditions all lead to different communication link commands. To adapt to these different links, an adaptive modulation and coding scheme (MCS) order needs to be selected based on the link quality to ensure high throughput and improve the utilization of wireless channel resources. Therefore, in link adaptation, accurate assessment of the channel state is crucial for ensuring the correct MCS selection. Since the MCS is configured at the transmitting end, and the link quality state is only known at the receiving end, the transmitting end typically sends a probe signal to the receiving end before transmitting data to obtain accurate and timely link state information from the receiving end. The receiving end measures the signal quality state based on the probe signal and feeds back Channel State Information (CSI) to the transmitting end. The transmitting end then sets the MCS and transmits data based on the received signal quality state information.

[0004] However, in satellite communication systems such as BeiDou short message service, due to limited air interface resources, it is not possible to set the MCS of the transmitting end by measuring channel quality through probe signals. Summary of the Invention

[0005] This application provides a method, system, and related apparatus for outbound data transmission in a BeiDou communication system, which enables the terminal to feed back the outbound MCS to the BeiDou network equipment without additional signaling overhead, thereby improving channel utilization.

[0006] In a first aspect, this application provides an outbound data transmission method in a BeiDou communication system, comprising: a first terminal sending a first user frame to a BeiDou network device, wherein the first user frame carries a first modulation and coding scheme (MCS) indicator field, the first MCS indicator field being used to suggest that the BeiDou network device use the first MCS for coding and modulation when sending the user frame of the first terminal; the first terminal receiving first outbound data sent by the BeiDou network device, the first outbound data including a first physical frame coded and modulated on a data channel and pilot information on a pilot channel; and the first terminal parsing a second user frame sent by the BeiDou network device to the first terminal from the first outbound data based on the first MCS.

[0007] The outbound data transmission method in the BeiDou communication system provided in this application embodiment enables the first terminal to carry MCS information in the first user frame of the incoming network and send it to the BeiDou network equipment, instructing the BeiDou network equipment to encode and modulate the service data sent to the first terminal according to the MCS information suggested by the terminal. In this way, the first terminal can feed back the outbound MCS to the BeiDou network equipment without additional signaling overhead, thereby improving channel utilization.

[0008] In one possible implementation, the first user frame is a data request frame. The header information of the data request frame includes a first MCS indicator field. The value of the first MCS indicator field is used to indicate the order of the first MCS. The data request frame is used to request the BeiDou network device to send service data to the first terminal. Before the first terminal sends the first user frame to the BeiDou network device, the method further includes: the first terminal receiving pilot information sent by the BeiDou network device on the pilot channel and measuring the channel quality on the pilot channel; the first terminal determining the channel quality of the data channel based on the channel quality on the pilot channel; and the first terminal determining the first MCS from the mapping relationship between the channel quality and the MCS based on the channel quality of the data channel.

[0009] In one possible implementation, the data request frame includes a service type field, which indicates the service type of the data request frame. The value of the service type field is a first value or a second value, wherein the first value indicates that the service type of the data request frame is a mailbox overview query service, and the second value indicates that the service type of the data request frame is a letter message download service.

[0010] Among them, the channel quality of the pilot channel includes the signal-to-noise ratio (SNR) of the pilot channel, and the channel quality of the data channel includes the SNR of the data channel.

[0011] The first terminal determines the SNR of the data channel using the following formula:

[0012] SNR d =SNR p +δ

[0013] Among them, SNR d SNR of the data channel p Let denoted as SNR of the pilot channel, and δ as the channel quality difference between the data channel and the pilot channel.

[0014] In this way, before the first terminal receives service data from the BeiDou network equipment, it needs to actively send a data request frame to the BeiDou network equipment. The first terminal can determine the MCS used by the BeiDou network equipment when sending service data by measuring the pilot channel. The first terminal can carry an MCS indication field in the data request frame, which can be used to indicate the MCS that the first terminal suggests the BeiDou network equipment should use when sending service data. In this way, the first terminal can complete the feedback of the outbound MCS to the BeiDou network equipment without additional signaling overhead, thus improving channel utilization.

[0015] In one possible implementation, the first user frame is an acknowledgment identifier (ACK) frame. Before the first terminal sends the first user frame to the BeiDou network device, the method further includes: the first terminal receiving second outgoing data sent by the BeiDou network device, the second outgoing data including a second physical frame encoded and modulated on the data channel and pilot information on the pilot channel; the first terminal using a third MCS to decode the third user frame from the second physical frame and measuring the channel quality on the data channel; the first terminal determining the first MCS based on the channel quality on the data channel, and the first user frame being used to indicate that the first terminal has received the third user frame.

[0016] In this way, when parsing the second user frame sent by the BeiDou network device, the first terminal can determine the MCS used by the BeiDou network device when sending service data to the first terminal by measuring the channel quality on the data channel. The first terminal can also include an MCS indication field in its ACK response to the BeiDou network device. This MCS indication field can be used to indicate the MCS used by the BeiDou network device when sending service data to the first terminal. This allows the first terminal to feed back the outbound MCS to the BeiDou network device without additional signaling overhead, thus improving channel utilization.

[0017] In one possible implementation, the frame header information of the first user frame includes a first MCS indicator field, the value of which is used to indicate the order of the first MCS, or the value of which is used to indicate the order of the first MCS compared with the third MCS.

[0018] In one possible implementation, the ACK field of the ACK frame includes a first MCS indicator field; wherein the value of the first MCS indicator field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS; or, the value of the first MCS indicator field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS compared with the second MCS. In this way, the ACK field can be reused as the MCS indicator field, saving frame header overhead.

[0019] In one possible implementation, after the first terminal parses the second user frame sent by the BeiDou network device to the first terminal from the first outgoing data based on the first MCS, the method further includes: the first terminal sending a first ACK, which indicates that the first terminal has received the second user frame sent by the BeiDou network device, wherein the first ACK includes a second MCS indication field, which suggests that the BeiDou network device use a fourth MCS for encoding and modulation when sending user frames to the first terminal; the first terminal receiving the third outgoing data sent by the BeiDou network device, wherein the third outgoing data includes a third physical frame encoded and modulated on the data channel and pilot information on the pilot channel; and the first terminal parses the fourth user frame sent by the BeiDou network device to the first terminal from the third outgoing data based on the fourth MCS.

[0020] Secondly, this application provides another method for outbound data transmission in a BeiDou communication system, comprising: a BeiDou network device receiving a first user frame sent by a first terminal, wherein the first user frame carries a first MCS indication field, the first MCS indication field being used to suggest that the BeiDou network device use the first MCS for encoding and modulation when sending the user frame of the first terminal; the BeiDou network device placing a second user frame to be sent to the first terminal into a first physical frame, and using the first MCS to encode and modulate the first physical frame; and the BeiDou network device sending first outbound data, the first outbound data including the first physical frame encoded and modulated on the data channel and pilot information on the pilot channel.

[0021] The outbound data transmission method in the BeiDou communication system provided in this application embodiment enables the first terminal to carry MCS information in the first user frame of the incoming network and send it to the BeiDou network equipment, instructing the BeiDou network equipment to encode and modulate the service data sent to the first terminal according to the MCS information suggested by the terminal. In this way, the first terminal can feed back the outbound MCS to the BeiDou network equipment without additional signaling overhead, thereby improving channel utilization.

[0022] In one possible implementation, the first user frame is a data request frame. The header information of the data request frame includes a first MCS indicator field. The value of the first MCS indicator field is used to indicate the order of the first MCS. The data request frame is used to request the BeiDou network device to send service data to the first terminal. After the BeiDou network device receives the first user frame sent by the first terminal, the method further includes: the BeiDou network device responding to the data request frame generates a first application layer message; the BeiDou network device splits the first application layer message into one or more user frames, and the one or more user frames include a second user frame.

[0023] In one possible implementation, the data request frame includes a service type field, which indicates the service type of the data request frame. The value of the service type field is a first value, which indicates that the service type of the data request frame is a mailbox overview query service. In response to the data request frame, the BeiDou network device generates a first application layer message, specifically including: the BeiDou network device generating the first application layer message based on the mailbox overview information of the first terminal, whereby the mailbox overview information of the first terminal includes one or more of the following: the number of email messages to be downloaded by the first terminal, the sending time, and the sender identifier.

[0024] In one possible implementation, the data request frame includes a service type field, which indicates the service type of the data request frame. The value of the service type field is a second value, which indicates that the service type of the data request frame is a mail message download service. In response to the data request frame, the BeiDou network device generates a first application layer message, specifically including: in response to the data request frame, the BeiDou network device queries the first mail message from the mailbox of the first terminal and generates the first application layer message based on the first mail message.

[0025] In this way, before the first terminal receives service data from the BeiDou network equipment, it needs to actively send a data request frame to the BeiDou network equipment. The first terminal can determine the MCS used by the BeiDou network equipment when sending service data by measuring the pilot channel. The first terminal can carry an MCS indication field in the data request frame, which can be used to indicate the MCS that the first terminal suggests the BeiDou network equipment should use when sending service data. In this way, the first terminal can complete the feedback of the outbound MCS to the BeiDou network equipment without additional signaling overhead, thus improving channel utilization.

[0026] In one possible implementation, the first user frame is an ACK frame; before the BeiDou network device receives the first user frame sent by the first terminal, the method further includes: the BeiDou network device puts the third user frame to be sent to the first terminal into the second physical frame, and uses the third MCS to encode and modulate the second physical frame, the second outgoing data includes the second physical frame encoded and modulated by the third MCS on the data channel and pilot information on the pilot channel, and the first user frame is used to indicate that the first terminal has received the third user frame.

[0027] In this way, when parsing the second user frame sent by the BeiDou network device, the first terminal can determine the MCS used by the BeiDou network device when sending service data to the first terminal by measuring the channel quality on the data channel. The first terminal can also include an MCS indication field in its ACK response to the BeiDou network device. This MCS indication field can be used to indicate the MCS used by the BeiDou network device when sending service data to the first terminal. This allows the first terminal to feed back the outbound MCS to the BeiDou network device without additional signaling overhead, thus improving channel utilization.

[0028] In one possible implementation, the frame header information of the first user frame includes a first MCS indicator field, the value of which is used to indicate the order of the first MCS, or the value of which is used to indicate the order of the first MCS compared with the third MCS.

[0029] In one possible implementation, the ACK field of the ACK frame includes a first MCS indication field; wherein the value of the first MCS indication field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS; or, the value of the first MCS indication field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS compared with the second MCS.

[0030] In one possible implementation, after the BeiDou network device sends the first outgoing data, the method further includes: the BeiDou network device receiving a first ACK sent by a first terminal, the first ACK indicating that the first terminal has received the second user frame sent by the BeiDou network device, wherein the first ACK includes a second MCS indication field, the second MCS indication field being used to suggest that the BeiDou network device use a fourth MCS for encoding and modulation when sending the user frame of the first terminal; the BeiDou network device placing the fourth user frame to be sent to the first terminal into a third physical frame, and using the fourth MCS to encode and modulate the third physical frame; the BeiDou network device sending third outgoing data, the third outgoing data including the fourth physical frame encoded and modulated on the data channel and pilot information on the pilot channel.

[0031] In one possible implementation, before the BeiDou network device receives the first user frame sent by the first terminal, the method further includes: the BeiDou network device receiving a fifth user frame sent by the second terminal, wherein the fifth user frame is used to suggest that the BeiDou network device use a fifth MCS for encoding and modulation when sending user frames from the second terminal; the BeiDou network device placing the second user frame to be sent to the first terminal into a first physical frame and using a first MCS to encode and modulate the first physical frame, specifically including: the BeiDou network device placing the second user frame to be sent to the first terminal and the fifth user frame to be sent to the second terminal into a first physical frame and using a first MCS to encode and modulate the first physical frame.

[0032] In one possible implementation, the order of the first MCS is less than the order of the fifth MCS.

[0033] In one possible implementation, the order of the first MCS is equal to the order of the fifth MCS.

[0034] In one possible implementation, the order of the first MCS is greater than the order of the fifth MCS.

[0035] Thirdly, this application provides another method for outbound data transmission in a BeiDou communication system, comprising: a BeiDou network device receiving a first user frame transmitted by a first terminal on an inbound channel; the BeiDou network device measuring the channel quality on the inbound channel when the first user frame is received; the BeiDou network device determining the channel quality of the data channel based on the channel quality on the inbound channel; the BeiDou network device determining the outbound MCS from the mapping relationship between channel quality and MCS based on the channel quality of the data channel; the BeiDou network device placing a second user frame to be transmitted to the first terminal into a first physical frame, and encoding and modulating the first physical frame using the outbound MCS; and the BeiDou network device transmitting first outbound data, the first outbound data including the first physical frame encoded and modulated on the data channel and pilot information on the pilot channel.

[0036] The outbound data transmission method in the BeiDou communication system provided in this application enables BeiDou network equipment to measure the channel quality of the inbound channel based on the data request frame sent by the first terminal, and then calculate the channel quality of the outbound data channel. Based on the channel quality of the data channel, the BeiDou network equipment can determine the outbound MCS. In this way, without additional signaling overhead, the BeiDou network equipment can select the outbound MCS, improving channel utilization.

[0037] Fourthly, this application provides a BeiDou communication system, comprising: a first terminal and a BeiDou network device; wherein the first terminal can execute the method in any of the possible implementations of the first aspect described above. The BeiDou network device can execute the method in any of the possible implementations of the first aspect described above.

[0038] Fifthly, this application provides a communication device including one or more processors, one or more memories, and a transceiver. The transceiver, the one or more memories, and the one or more processors are coupled together. The one or more memories are used to store computer program code, which includes computer instructions. When the one or more processors execute the computer instructions, the communication device performs the method in any of the possible implementations of the first aspect described above.

[0039] The communication device can be a terminal or other product-type equipment.

[0040] Sixthly, this application provides a communication device including one or more processors, one or more memories, and a transceiver. The transceiver, the one or more memories, and the one or more processors are coupled together. The one or more memories are used to store computer program code, which includes computer instructions. When the one or more processors execute the computer instructions, the communication device performs the method in any of the possible implementations of the second aspect described above.

[0041] The communication device can be a BeiDou network device, or any network element or a combination of multiple network elements in a BeiDou network device.

[0042] In a seventh aspect, this application provides a computer storage medium including computer instructions that, when executed on a computer, cause the computer to perform the method in any possible implementation of the first aspect described above.

[0043] Eighthly, this application provides a computer storage medium including computer instructions that, when executed on a computer, cause the computer to perform the method in any possible implementation of the second aspect described above.

[0044] Ninthly, this application provides a computer program product that, when run on a computer, causes the computer to perform the method in any possible implementation of the first aspect described above.

[0045] In a tenth aspect, this application provides a computer program product that, when run on a computer, causes the computer to perform the method in any possible implementation of the second aspect described above.

[0046] In one aspect, this application provides a chip or chip system for use in a terminal, including a processing circuit and an interface circuit. The interface circuit is used to receive code instructions and transmit them to the processing circuit, and the processing circuit is used to run the code instructions to perform the method in any possible implementation of the first aspect above. Attached Figure Description

[0047] Figure 1 This application provides a schematic diagram of the architecture of a BeiDou communication system.

[0048] Figure 2A This application provides a schematic diagram of the data inbound transmission process in a BeiDou communication system, as illustrated in an embodiment of the present application.

[0049] Figure 2B This application provides a schematic diagram of the data outgoing transmission process in a BeiDou communication system, as illustrated in an embodiment of the present application.

[0050] Figure 3 A schematic diagram of SNR versus throughput curves provided for embodiments of this application;

[0051] Figure 4 A flowchart illustrating an MCS selection method provided in an embodiment of this application;

[0052] Figure 5 A flowchart illustrating the MCS selection method in a cellular network provided in this application embodiment;

[0053] Figure 6 This is a schematic diagram of the terminal structure provided in the embodiments of this application;

[0054] Figure 7 A schematic diagram of the protocol encapsulation architecture for outbound data of a Beidou communication system provided in this application embodiment;

[0055] Figure 8 A schematic diagram of the protocol parsing architecture for outbound data of a Beidou communication system provided in this application embodiment;

[0056] Figure 9 A flowchart illustrating an outbound data transmission method in a BeiDou communication system, provided as an embodiment of this application;

[0057] Figure 10A This is a schematic diagram of the frame format of a data request frame provided in an embodiment of this application;

[0058] Figure 10B A schematic diagram of user frame scheduling provided in an embodiment of this application;

[0059] Figure 11 A flowchart illustrating another outbound data transmission method in a BeiDou communication system provided in this application embodiment;

[0060] Figure 12A This is a schematic diagram of the frame format of an ACK frame provided in an embodiment of this application;

[0061] Figure 12B A schematic diagram of another ACK frame format provided in an embodiment of this application;

[0062] Figure 13 A flowchart illustrating another outbound data transmission method in a BeiDou communication system provided in this application embodiment;

[0063] Figure 14 A schematic diagram of another data request frame format provided in an embodiment of this application;

[0064] Figure 15 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0065] Figure 16 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0066] Figure 17 This is a schematic diagram of another communication device provided in an embodiment of this application;

[0067] Figure 18 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0068] The technical solutions in the embodiments of this application will now be described clearly and in detail with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; the word "and / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0069] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0070] The following describes a BeiDou communication system 10 provided in the embodiments of this application.

[0071] Figure 1 A schematic diagram of the architecture of a Beidou communication system 10 provided in an embodiment of this application is shown.

[0072] As above Figure 1As shown, the BeiDou communication system 10 may include a terminal 100, a BeiDou short message satellite 21, a BeiDou network device 200, a short message center 25, and a terminal 300. Optionally, the BeiDou communication system 10 may also include a national emergency rescue platform 26 and a national emergency rescue center 27.

[0073] Terminal 100 can send short message information to BeiDou short message satellite 21. BeiDou short message satellite 21 only acts as a relay, directly forwarding the short message information sent by terminal 100 to BeiDou network equipment 200 on the ground. BeiDou network equipment 200 can parse the short message information forwarded by the satellite according to the BeiDou communication protocol and forward the message content of the general message type parsed from the short message information to the short message service center (SMSC) 25. Short message service center 25 can forward the message content to terminal 300 through traditional cellular communication network. BeiDou network equipment 200 can also send emergency distress messages sent by terminal 100 to the National Emergency Rescue Center 27 through the National Emergency Rescue Platform 26.

[0074] Terminal 300 can also send short messages to Short Message Service (SMS) Center 25 via traditional cellular communication networks. SMS Center 25 can forward the short messages from Terminal 300 to BeiDou network device 200. BeiDou network device 200 can then relay the short messages from Terminal 300 to Terminal 100 via BeiDou short message satellite 21.

[0075] The aforementioned BeiDou network equipment 200 may include a BeiDou ground transceiver station 22, a BeiDou central station 23, and a BeiDou short message fusion communication platform 24. The BeiDou ground transceiver station 22 may include one or more devices with transmitting and receiving functions, or it may include one or more devices with both transmitting and receiving functions; this is not limited here. The BeiDou ground transceiver station 22 can be used by the BeiDou network equipment 200 for data processing at the physical layer protocol (PHY). The BeiDou central station 23 can be used by the BeiDou network equipment 200 for data processing at the satellite link control protocol (SLC) layer and the message data convergence protocol (MDCP) layer. The BeiDou short message fusion communication platform 24 can be used for data processing at the application layer protocol (APP).

[0076] Because the BeiDou-10 communication system communicates via satellite links, its main characteristics are: long latency (approximately 270ms one-way) and high link loss. Currently, the BeiDou-10 communication system mainly supports bursty short message services and does not support connection state management, mobility management, broadcast control information, etc.

[0077] Terminal 100 can actively send data to BeiDou network equipment 200 via BeiDou short message satellite 21. However, due to the lack of air interface signaling, the ground central station cannot actively page the user. Because satellite communication has a long propagation distance, the BeiDou communication system 10 requires high transmission power from terminal 100. Limited by the current radio frequency (RF) devices on terminal 100, terminal 100 cannot continuously send signals to BeiDou short message satellite 21 for extended periods. To minimize damage to the RF devices on terminal 100, after continuous operation in the transmission state for a period, the RF devices of terminal 100 must stop working for a period before switching back to the transmission state. The duration of the transmission state on terminal 100 is determined by the underlying hardware capabilities of terminal 100. In the aforementioned BeiDou communication system 10, to ensure that the data received and transmitted by terminal 100 do not interfere with each other, terminal 100 does not support simultaneous data transmission and reception. Terminal 100 needs to send data first and then wait to receive data sent by BeiDou network equipment 200.

[0078] Among them, the Beidou network device 200 can operate in full-duplex mode, which can send and receive data simultaneously, and the Beidou network device 200 can send and receive data for a long time.

[0079] Figure 2A This illustration shows the data inbound transmission process in a BeiDou communication system provided in an embodiment of this application.

[0080] like Figure 2A As shown, data inbound can refer to terminal 100 sending data to BeiDou network device 200. For example, terminal 100 can send data frames to BeiDou ground transceiver station 22. BeiDou ground transceiver station 22 can send the data frames to BeiDou central station 23. BeiDou central station 23 can aggregate the data frames into application layer messages and report them to BeiDou short message fusion communication platform 24. After receiving the data frames sent by terminal 100, BeiDou central station 23 can return an SLC layer acknowledgment character (ACK) to terminal 100. This ACK can be used to indicate whether BeiDou network device 200 has successfully received the data frames sent by terminal 100.

[0081] Figure 2B This illustration shows the data outgoing transmission process in a BeiDou communication system provided in an embodiment of this application.

[0082] like Figure 2BAs shown, data outbound refers to the BeiDou network device 200 sending data to the terminal 100. For example, the BeiDou short message fusion communication platform 24 in the BeiDou network device 200 can send application layer messages to the BeiDou central station 23; then the BeiDou central station 23 can split the application layer message into one or more data frames and send them to the BeiDou ground transceiver station 22, which is then relayed by the BeiDou short message satellite 21 and sent to the terminal 100. After receiving the data frame, the terminal 100 can return an SLC layer ACK to the BeiDou central station 23. This ACK can be used to determine whether the terminal 100 has successfully received the data frame sent by the BeiDou network device 200.

[0083] The encoding and modulation involved in the embodiments of this application are described below.

[0084] To withstand the harsh environment of wireless channel signal transmission, the transmitting end must convert the transmitted signal into a form suitable for transmission on a specific channel; this is known as coding and modulation. Generally, coding and modulation involves adding redundant bits to the information signal to be transmitted to resist transmission failures caused by channel quality degradation. When channel quality is good, the proportion of effective information can be increased by reducing the amount of redundant bits, thereby increasing transmission throughput. Conversely, the overhead of redundant bits needs to be increased to ensure that communication information can be transmitted at low rates. Channel quality can be measured by the signal-to-noise ratio (SNR).

[0085] Figure 3 A schematic diagram of the SNR versus throughput curves provided in an embodiment of this application is shown.

[0086] like Figure 3 As shown, different SNRs have an optimal MCS selection. Therefore, how to choose the MCS is a key factor in improving channel transmission throughput in wireless transmission. The modulation scheme in the MCS can include binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), 64QAM, etc. The coding rate in the MCS can include 1 / 2, 3 / 4, etc.

[0087] For example, when the SNR is greater than 25 dB, the channel transmission throughput is highest when a 64QAM-3 / 4 rate MCS is selected. When the SNR is 20 dB, the channel transmission throughput is highest when a 16QAM-3 / 4 rate MCS is selected. The above examples are merely for illustrative purposes and should not be construed as limiting the scope of this application.

[0088] The following describes an MCS selection method provided by an embodiment of this application.

[0089] Figure 4 The diagram illustrates a flowchart of an MCS selection method provided in an embodiment of this application.

[0090] In wireless communication, the different locations of users, communication times, and weather conditions all lead to different communication link commands. To adapt to these different communication links, an adaptive modulation and coding scheme (MCS) order needs to be selected based on the varying quality of the communication link to ensure high throughput and improve the utilization of wireless channel resources. Therefore, in link adaptation, accurate assessment of the channel state is a key factor in ensuring the correct MCS selection. However, since the MCS is configured at the transmitting end, the link quality state is only known at the receiving end.

[0091] Therefore, as Figure 4 As shown, the general MCS selection method may include the following steps:

[0092] 1. The transmitting end sends a probe signal to the receiving end.

[0093] 2. The receiving end evaluates the quality of the receiving channel based on the received probe signal.

[0094] 3. The receiving end feeds back the quality of the receiving channel to the sending end.

[0095] 4. The transmitting end selects a suitable MCS based on the feedback channel quality.

[0096] 5. The sending end sends data according to the selected MCS.

[0097] Figure 5 A flowchart illustrating the MCS selection method in a cellular network is shown.

[0098] like Figure 5 As shown, in cellular networks, such as LTE and 5G-NR, the MCS can be selected through the following steps:

[0099] 1. The base station sends system messages to the terminal.

[0100] 2. After receiving the system message, the terminal initiates a connection establishment request to the base station.

[0101] 3. After receiving the connection establishment request, the base station establishes a complete connection with the terminal.

[0102] 4. The base station sends RRC signaling to the terminal, whereby the RRC signaling is used to configure the terminal's measurement signal, measurement mode, and reporting mode.

[0103] 5. After receiving the RRC signaling, the terminal completes the configuration of the measurement signal, measurement mode and reporting mode, starts channel measurement and obtains the measurement results.

[0104] 6. The terminal reports the measurement results to the base station.

[0105] 7. Based on the measurement results, the base station sets up an appropriate MCS and sends service data.

[0106] As can be seen from the above MCS selection method, the base station needs to interact with the terminal through signaling before transmitting data to complete the MCS selection. However, in long-distance communication links such as satellite communication, the channel transmission delay is long and air interface resources are limited. Frequent interactions between the terminal and the network side will lead to excessive data transmission delay and consume a lot of air interface resources. Therefore, the above MCS selection method is not suitable for satellite communication systems such as the BeiDou communication system.

[0107] Therefore, this application provides an outbound data transmission method in a BeiDou communication system, which enables the first user frame (including a data request frame or ACK frame) of the terminal 100 to carry MCS information and send it to the BeiDou network device 200, instructing the BeiDou network device 200 to encode and modulate the service data sent to the terminal 100 according to the MCS information indicated by the terminal 100. In this way, the terminal 100 can feed back the outbound MCS to the BeiDou network device 200 without additional signaling overhead, thereby improving channel utilization.

[0108] Figure 6 A schematic diagram of the terminal 100 is shown.

[0109] The following description uses terminal 100 as an example to illustrate the embodiment. It should be understood that... Figure 6 The terminal 100 shown is merely an example, and terminal 100 can have more than... Figure 6 The more or fewer components shown can be combined into two or more components, or they can have different component configurations. Figure 6 The various components shown can be implemented in hardware, software, or a combination of hardware and software, including one or more signal processing and / or application-specific integrated circuits.

[0110] Terminal 100 may include: processor 110, external memory interface 120, internal memory 121, universal serial bus (USB) interface 130, charging management module 140, power management module 141, battery 142, antenna 1, antenna 2, mobile communication module 150, wireless communication module 160, audio module 170, speaker 170A, receiver 170B, microphone 170C, headphone jack 170D, sensor module 180, button 190, motor 191, indicator 192, camera 193, display screen 194, and subscriber identification module (SIM) card interface 195, etc. The sensor module 180 may include a pressure sensor 180A, a gyroscope sensor 180B, a barometric pressure sensor 180C, a magnetic sensor 180D, an accelerometer sensor 180E, a distance sensor 180F, a proximity sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, a bone conduction sensor 180M, etc.

[0111] It is understood that the structure illustrated in the embodiments of the present invention does not constitute a specific limitation on the terminal 100. In other embodiments of this application, the terminal 100 may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0112] Processor 110 may include one or more processing units, such as: application processor (AP), modem processor, graphics processing unit (GPU), image signal processor (ISP), controller, memory, video codec, digital signal processor (DSP), baseband processor, and / or neural network processing unit (NPU), etc. Different processing units may be independent devices or integrated into one or more processors.

[0113] The controller can serve as the central nervous system and command center of the terminal 100. The controller can generate operation control signals based on the instruction opcode and timing signals to control the fetching and execution of instructions.

[0114] The processor 110 may also include a memory for storing instructions and data. In some embodiments, the memory in the processor 110 is a cache memory. This memory can store instructions or data that the processor 110 has just used or that are used repeatedly. If the processor 110 needs to use the instruction or data again, it can retrieve it directly from the memory. This avoids repeated accesses, reduces the waiting time of the processor 110, and thus improves the efficiency of the system.

[0115] In some embodiments, the processor 110 may include one or more interfaces. Interfaces may include an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a subscriber identity module (SIM) interface, and / or a universal serial bus (USB) interface, etc.

[0116] The I2C interface is a bidirectional synchronous serial bus, including a serial data line (SDA) and a serial clock line (SCL). In some embodiments, the processor 110 may include multiple I2C buses. The processor 110 can couple to the touch sensor 180K, charger, flash, camera 193, etc., through different I2C bus interfaces. For example, the processor 110 can couple to the touch sensor 180K through the I2C interface, enabling the processor 110 and the touch sensor 180K to communicate through the I2C bus interface, thereby realizing the touch function of the terminal 100.

[0117] The I2S interface can be used for audio communication. In some embodiments, the processor 110 may include multiple I2S buses. The processor 110 can be coupled to the audio module 170 via the I2S bus to enable communication between the processor 110 and the audio module 170. In some embodiments, the audio module 170 can transmit audio signals to the wireless communication module 160 via the I2S interface to enable the function of answering phone calls through a Bluetooth headset.

[0118] The PCM interface can also be used for audio communication, sampling, quantizing, and encoding analog signals. In some embodiments, the audio module 170 and the wireless communication module 160 can be coupled via the PCM bus interface. In some embodiments, the audio module 170 can also transmit audio signals to the wireless communication module 160 via the PCM interface, enabling the function of answering phone calls through a Bluetooth headset. Both the I2S interface and the PCM interface can be used for audio communication.

[0119] The UART interface is a universal serial data bus used for asynchronous communication. This bus can be a bidirectional communication bus. It converts the data to be transmitted between serial and parallel communication. In some embodiments, the UART interface is typically used to connect the processor 110 and the wireless communication module 160. For example, the processor 110 communicates with the Bluetooth module in the wireless communication module 160 via the UART interface to implement Bluetooth functionality. In some embodiments, the audio module 170 can transmit audio signals to the wireless communication module 160 via the UART interface to enable music playback through Bluetooth headphones.

[0120] The MIPI interface can be used to connect the processor 110 to peripheral devices such as the display screen 194 and the camera 193. The MIPI interface includes a camera serial interface (CSI) and a display serial interface (DSI). In some embodiments, the processor 110 and the camera 193 communicate via the CSI interface to enable the shooting function of the terminal 100. The processor 110 and the display screen 194 communicate via the DSI interface to enable the display function of the terminal 100.

[0121] The GPIO interface can be configured via software. It can be configured as a control signal or a data signal. In some embodiments, the GPIO interface can be used to connect the processor 110 to a camera 193, a display screen 194, a wireless communication module 160, an audio module 170, a sensor module 180, etc. The GPIO interface can also be configured as an I2C interface, an I2S interface, a UART interface, a MIPI interface, etc.

[0122] USB port 130 is a USB standard compliant interface, specifically a Mini USB port, Micro USB port, USB Type-C port, etc. USB port 130 can be used to connect a charger to charge terminal 100, and can also be used for data transfer between terminal 100 and peripheral devices. It can also be used to connect headphones for audio playback. This interface can also be used to connect other electronic devices, such as AR devices.

[0123] It is understood that the interface connection relationships between the modules illustrated in the embodiments of the present invention are merely illustrative and do not constitute a structural limitation on the terminal 100. In other embodiments of this application, the terminal 100 may also adopt different interface connection methods or a combination of multiple interface connection methods as described in the above embodiments.

[0124] The charging management module 140 receives charging input from a charger. The charger can be a wireless charger or a wired charger. In some wired charging embodiments, the charging management module 140 receives charging input from the wired charger via the USB interface 130. In some wireless charging embodiments, the charging management module 140 receives wireless charging input via the wireless charging coil of the terminal 100. While charging the battery 142, the charging management module 140 can also supply power to the electronic device via the power management module 141.

[0125] The power management module 141 connects the battery 142, the charging management module 140, and the processor 110. The power management module 141 receives input from the battery 142 and / or the charging management module 140, providing power to the processor 110, internal memory 121, external memory, display screen 194, camera 193, and wireless communication module 160, etc. The power management module 141 can also monitor parameters such as battery capacity, battery cycle count, and battery health status (leakage current, impedance). In some other embodiments, the power management module 141 may also be located within the processor 110. In other embodiments, the power management module 141 and the charging management module 140 may be located in the same device.

[0126] The wireless communication function of terminal 100 can be implemented through antenna 1, antenna 2, mobile communication module 150, wireless communication module 160, modem processor and baseband processor, etc.

[0127] Antennas 1 and 2 are used to transmit and receive electromagnetic wave signals. Each antenna in terminal 100 can be used to cover one or more communication frequency bands. Different antennas can also be multiplexed to improve antenna utilization. For example, antenna 1 can be multiplexed as a diversity antenna for a wireless local area network. In some other embodiments, the antennas can be used in conjunction with tuning switches.

[0128] The mobile communication module 150 can provide solutions for wireless communication applications including 2G / 3G / 4G / 5G on the terminal 100. The mobile communication module 150 may include at least one filter, switch, power amplifier, low-noise amplifier (LNA), etc. The mobile communication module 150 can receive electromagnetic waves via the antenna 1, and perform filtering, amplification, and other processing on the received electromagnetic waves before transmitting them to the modem processor for demodulation. The mobile communication module 150 can also amplify the signal modulated by the modem processor and convert it into electromagnetic waves for radiation via the antenna 1. In some embodiments, at least some functional modules of the mobile communication module 150 may be housed in the processor 110. In some embodiments, at least some functional modules of the mobile communication module 150 and at least some modules of the processor 110 may be housed in the same device.

[0129] The modem processor may include a modulator and a demodulator. The modulator modulates the low-frequency baseband signal to be transmitted into a mid-to-high frequency signal. The demodulator demodulates the received electromagnetic wave signal into a low-frequency baseband signal. The demodulator then transmits the demodulated low-frequency baseband signal to the baseband processor for processing. After processing by the baseband processor, the low-frequency baseband signal is transmitted to the application processor. The application processor outputs sound signals through an audio device (not limited to speaker 170A, receiver 170B, etc.) or displays images or videos through the display screen 194. In some embodiments, the modem processor may be a separate device. In other embodiments, the modem processor may be independent of the processor 110 and may be housed in the same device as the mobile communication module 150 or other functional modules.

[0130] The wireless communication module 160 can provide solutions for wireless communication applications on the terminal 100, including wireless local area networks (WLAN) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), satellite communication modules, frequency modulation (FM), near field communication (NFC), and infrared (IR) technologies. The wireless communication module 160 can be one or more devices integrating at least one communication processing module. The wireless communication module 160 receives electromagnetic waves via antenna 2, performs frequency modulation and filtering of the electromagnetic wave signals, and sends the processed signal to processor 110. The wireless communication module 160 can also receive signals to be transmitted from processor 110, perform frequency modulation and amplification, and convert them into electromagnetic waves for radiation via antenna 2.

[0131] Among them, the satellite communication module can be used to communicate with satellite network equipment. For example, in the BeiDou communication system, the satellite communication module can communicate with BeiDou network equipment 200, and the satellite communication module can support short message transmission between BeiDou network equipment 200.

[0132] In some embodiments, antenna 1 of terminal 100 is coupled to mobile communication module 150, and antenna 2 is coupled to wireless communication module 160, enabling terminal 100 to communicate with networks and other devices via wireless communication technology. The wireless communication technology may include Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Time Division Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), BT, GNSS, WLAN, NFC, FM, and / or IR technologies, etc. The GNSS may include the Global Positioning System (GPS), the Global Navigation Satellite System (GLONASS), the BeiDou Navigation Satellite System (BDS), the Quasi-Zenith Satellite System (QZSS), and / or satellite-based augmentation systems (SBAS).

[0133] Terminal 100 implements display functions through a GPU, display screen 194, and application processor. The GPU is a microprocessor for image processing, connected to the display screen 194 and the application processor. The GPU is used to perform mathematical and geometric calculations and for graphics rendering. Processor 110 may include one or more GPUs, which execute program instructions to generate or modify display information.

[0134] Display screen 194 is used to display images, videos, etc. Display screen 194 includes a display panel. The display panel may be a liquid crystal display (LCD), an organic light-emitting diode (OLED), an active-matrix organic light-emitting diode (AMOLED), a flexible light-emitting diode (FLED), a miniature LED, a microLED, a quantum dot light-emitting diode (QLED), etc. In some embodiments, terminal 100 may include one or N displays 194, where N is a positive integer greater than 1.

[0135] Terminal 100 can perform shooting functions through ISP, camera 193, video codec, GPU, display 194 and application processor.

[0136] The ISP (Image Signal Processor) is used to process data fed back from the camera 193. For example, when taking a picture, the shutter is opened, and light is transmitted through the lens to the camera's photosensitive element. The light signal is converted into an electrical signal, and the camera's photosensitive element transmits the electrical signal to the ISP for processing, transforming it into an image visible to the naked eye. The ISP can also perform algorithmic optimization of image noise, brightness, and skin tone. The ISP can also optimize parameters such as exposure and color temperature of the shooting scene. In some embodiments, the ISP can be set in the camera 193.

[0137] Camera 193 is used to capture still images or videos. An object is projected onto a photosensitive element by generating an optical image through the lens. The photosensitive element can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) phototransistor. The photosensitive element converts the light signal into an electrical signal, which is then passed to an ISP for conversion into a digital image signal. The ISP outputs the digital image signal to a DSP for processing. The DSP converts the digital image signal into image signals in standard RGB, YUV, or other formats. In some embodiments, terminal 100 may include one or N cameras 193, where N is a positive integer greater than 1.

[0138] A digital signal processor (DSP) is used to process digital signals. Besides digital image signals, it can also process other digital signals. For example, when terminal 100 selects a frequency point, the DSP can perform Fourier transforms on the frequency energy.

[0139] Video codecs are used to compress or decompress digital video. Terminal 100 may support one or more video codecs. Thus, terminal 100 can play or record videos in various encoding formats, such as Moving Picture Experts Group (MPEG) 1, MPEG 2, MPEG 3, MPEG 4, etc.

[0140] NPU stands for Neural Network (NN) Computing Processor. By borrowing the structure of biological neural networks, such as the transmission patterns between neurons in the human brain, it can rapidly process input information and continuously learn on its own. NPUs can enable intelligent cognitive applications in terminals, such as image recognition, facial recognition, speech recognition, and text understanding.

[0141] The external storage interface 120 can be used to connect an external storage card, such as a Micro SD card, to expand the storage capacity of the terminal 100. The external storage card communicates with the processor 110 through the external storage interface 120 to perform data storage functions. For example, music, video, and other files can be saved on the external storage card.

[0142] Internal memory 121 can be used to store computer executable program code, which includes instructions. Processor 110 executes various functional applications and data processing of terminal 100 by running the instructions stored in internal memory 121. Internal memory 121 may include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback, image playback, etc.), etc. The data storage area may store data created during the use of terminal 100 (such as audio data, phonebook, etc.). Furthermore, internal memory 121 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, universal flash storage (UFS), etc.

[0143] Terminal 100 can implement audio functions, such as music playback and recording, through audio module 170, speaker 170A, receiver 170B, microphone 170C, headphone jack 170D, and application processor.

[0144] The audio module 170 is used to convert digital audio information into analog audio signals for output, and also to convert analog audio input into digital audio signals. The audio module 170 can also be used for encoding and decoding audio signals. In some embodiments, the audio module 170 may be located in the processor 110, or some functional modules of the audio module 170 may be located in the processor 110.

[0145] The speaker 170A, also known as a "loudspeaker," is used to convert audio electrical signals into sound signals. The terminal 100 can listen to music or make hands-free calls through the speaker 170A.

[0146] The receiver 170B, also known as the "earpiece," is used to convert audio electrical signals into sound signals. When the terminal 100 receives a phone call or voice message, the receiver 170B can be brought close to the listener's ear to hear the voice.

[0147] Microphone 170C, also known as a "microphone" or "voice transducer," is used to convert sound signals into electrical signals. When making a phone call or sending a voice message, the user can speak by bringing their mouth close to microphone 170C, inputting the sound signal into microphone 170C. Terminal 100 may have at least one microphone 170C. In some embodiments, terminal 100 may have two microphones 170C, which, in addition to collecting sound signals, can also perform noise reduction. In other embodiments, terminal 100 may have three, four, or more microphones 170C, which can collect sound signals, reduce noise, identify the sound source, and perform directional recording, etc.

[0148] The 170D headphone jack is used to connect wired headphones. The 170D headphone jack can be a USB 130 interface or a 3.5mm Open Mobile Terminal Platform (OMTP) standard interface, a CTIA (Cellular Telecommunications Industry Association of the USA) standard interface.

[0149] Pressure sensor 180A is used to sense pressure signals and convert them into electrical signals. In some embodiments, pressure sensor 180A can be disposed on display screen 194. There are many types of pressure sensors 180A, such as resistive pressure sensors, inductive pressure sensors, and capacitive pressure sensors. A capacitive pressure sensor may include at least two parallel plates with conductive material. When force is applied to pressure sensor 180A, the capacitance between the electrodes changes. Terminal 100 determines the pressure intensity based on the change in capacitance. When a touch operation is applied to display screen 194, terminal 100 detects the intensity of the touch operation based on pressure sensor 180A. Terminal 100 can also calculate the touch position based on the detection signal from pressure sensor 180A. In some embodiments, touch operations applied to the same touch position but with different touch operation intensities can correspond to different operation commands. For example: when a touch operation with an intensity less than a first pressure threshold is applied to the SMS application icon, a command to view an SMS is executed. When a touch operation with an intensity greater than or equal to the first pressure threshold is applied to the SMS application icon, a command to create a new SMS is executed.

[0150] The gyroscope sensor 180B can be used to determine the motion attitude of the terminal 100. In some embodiments, the gyroscope sensor 180B can determine the angular velocity of the terminal 100 around three axes (i.e., the x, y, and z axes). The gyroscope sensor 180B can be used for image stabilization. For example, when the shutter is pressed, the gyroscope sensor 180B detects the angle of the terminal 100's shake, calculates the distance that the lens module needs to compensate based on the angle, and allows the lens to counteract the shake of the terminal 100 through reverse movement, thus achieving image stabilization. The gyroscope sensor 180B can also be used in navigation and motion-sensing game scenarios.

[0151] The barometric pressure sensor 180C is used to measure air pressure. In some embodiments, the terminal 100 calculates altitude using the air pressure value measured by the barometric pressure sensor 180C to assist in positioning and navigation.

[0152] The magnetic sensor 180D includes a Hall sensor. The terminal 100 can use the magnetic sensor 180D to detect the opening and closing of the flip cover. In some embodiments, when the terminal 100 is a flip phone, the terminal 100 can detect the opening and closing of the flip cover using the magnetic sensor 180D. Then, based on the detected opening and closing state of the cover or the flip cover, features such as automatic flip unlocking can be set.

[0153] The 180E accelerometer can detect the magnitude of acceleration of terminal 100 in various directions (typically three axes). When terminal 100 is stationary, it can detect the magnitude and direction of gravity. It can also be used to identify the posture of electronic devices, and is applied to applications such as screen orientation switching and pedometers.

[0154] A distance sensor 180F is used to measure distance. The terminal 100 can measure distance via infrared or laser. In some embodiments, during a shooting scene, the terminal 100 can utilize the distance sensor 180F to measure distance for rapid focusing.

[0155] The proximity sensor 180G may include, for example, a light-emitting diode (LED) and a light detector, such as a photodiode. The LED may be an infrared LED. The terminal 100 emits infrared light outward through the LED. The terminal 100 uses the photodiode to detect infrared reflected light from nearby objects. When sufficient reflected light is detected, it can be determined that there is an object near the terminal 100. When insufficient reflected light is detected, the terminal 100 can determine that there is no object near the terminal 100. The terminal 100 may use the proximity sensor 180G to detect when a user holds the terminal 100 close to their ear for a call, so as to automatically turn off the screen to save power. The proximity sensor 180G can also be used in holster mode and pocket mode for automatic unlocking and screen locking.

[0156] The ambient light sensor 180L is used to sense the ambient light intensity. The terminal 100 can adaptively adjust the brightness of the display screen 194 based on the sensed ambient light intensity. 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 work with the proximity sensor 180G to detect whether the terminal 100 is in a pocket to prevent accidental touches.

[0157] The fingerprint sensor 180H is used to collect fingerprints. The terminal 100 can use the characteristics of the collected fingerprints to unlock the device, access application locks, take photos with fingerprints, and answer calls with fingerprints.

[0158] Temperature sensor 180J is used to detect temperature. In some embodiments, terminal 100 uses the temperature detected by temperature sensor 180J to execute a temperature processing strategy. For example, when the temperature reported by temperature sensor 180J exceeds a threshold, terminal 100 reduces the performance of the processor located near temperature sensor 180J to reduce power consumption and implement thermal protection. In other embodiments, when the temperature is below another threshold, terminal 100 heats battery 142 to prevent abnormal shutdown of terminal 100 due to low temperature. In still other embodiments, when the temperature is below yet another threshold, terminal 100 boosts the output voltage of battery 142 to prevent abnormal shutdown due to low temperature.

[0159] Touch sensor 180K, also known as a "touch panel," can be located on display screen 194. The touch sensor 180K and display screen 194 together form a touchscreen, also known as a "touchscreen." Touch sensor 180K detects touch operations applied to or near it. The touch sensor can transmit 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 display screen 194. In other embodiments, touch sensor 180K may also be located on the surface of terminal 100, in a different position than display screen 194.

[0160] The bone conduction sensor 180M can acquire vibration signals. In some embodiments, the bone conduction sensor 180M can acquire vibration signals from the vibrating bone segments of the human vocal cords. The bone conduction sensor 180M can also contact the human pulse to receive blood pressure signals. In some embodiments, the bone conduction sensor 180M can also be incorporated into headphones to form bone conduction headphones. The audio module 170 can parse the voice signals from the vibrating bone segments of the vocal cords acquired by the bone conduction sensor 180M to realize voice functionality. The application processor can parse heart rate information from the blood pressure signals acquired by the bone conduction sensor 180M to realize heart rate detection functionality.

[0161] Buttons 190 include a power button, volume buttons, etc. Buttons 190 can be mechanical buttons or touch-sensitive buttons. Terminal 100 can receive button input and generate key signal inputs related to user settings and function control of terminal 100.

[0162] Motor 191 can generate vibration alerts. Motor 191 can be used for incoming call vibration alerts or for touch vibration feedback. For example, different vibration feedback effects can correspond to touch operations performed on different applications (such as taking photos, playing audio, etc.). Motor 191 can also correspond to different vibration feedback effects for touch operations performed on different areas of the display screen 194. Different application scenarios (such as time reminders, receiving messages, alarm clocks, games, etc.) can also correspond to different vibration feedback effects. The touch vibration feedback effect can also be customized.

[0163] Indicator 192 can be an indicator light, used to indicate charging status, power changes, or to indicate messages, missed calls, notifications, etc.

[0164] The SIM card interface 195 is used to connect a SIM card. The SIM card can be inserted into or removed from the SIM card interface 195 to make contact with and separate from the terminal 100. The terminal 100 can support one or N SIM card interfaces, where N is a positive integer greater than 1. The SIM card interface 195 can support Nano SIM cards, Micro SIM cards, SIM cards, etc. Multiple cards can be inserted into the same SIM card interface 195 simultaneously. The multiple cards can be of the same or different types. The SIM card interface 195 is also compatible with different types of SIM cards. The SIM card interface 195 is also compatible with external memory cards. The terminal 100 interacts with the network through the SIM card to realize functions such as calls and data communication. In some embodiments, the terminal 100 uses an eSIM, i.e., an embedded SIM card. The eSIM card can be embedded in the terminal 100 and cannot be separated from the terminal 100.

[0165] The following describes a protocol encapsulation architecture for outbound data of a Beidou communication system 10 provided in the embodiments of this application.

[0166] Figure 7 This paper illustrates a schematic diagram of the protocol encapsulation architecture for outbound data of a Beidou communication system 10 provided in an embodiment of this application.

[0167] like Figure 7 As shown, the BeiDou short message transmission protocol layer in the BeiDou network equipment 200 can be divided into an application layer protocol, a message data convergence protocol (MDCP), a satellite link control protocol (SLC), and a physical layer protocol (PHY). The BeiDou network equipment 200 may include a BeiDou ground transceiver station 22, a BeiDou central station 23, and a BeiDou short message fusion communication platform 24. The BeiDou ground transceiver station 22 is responsible for protocol processing at the PHY layer. The BeiDou central station 23 is responsible for protocol processing at the SLC and MDCP layers. The BeiDou short message fusion communication platform 24 is responsible for protocol processing at the APP layer.

[0168] When BeiDou network device 200 sends data to terminal 100, the workflow of the BeiDou short message transmission protocol in BeiDou network device 200 can be as follows:

[0169] At the APP layer, the BeiDou network device 200 can compress the raw data into compressed data using a compression algorithm, and add a compression indicator field to the front of the compressed data. This compression indicator field indicates the type of compression algorithm used. Next, the BeiDou network device 200 can encrypt the compressed data, obtaining encrypted data, and add an encryption algorithm field to the header of the encrypted data. This encryption algorithm field indicates the type of encryption algorithm used. The BeiDou network device 200 can then encapsulate the encrypted data, the compression indicator field, and the encryption indicator field into an application layer message and send it to the MDCP layer. This application layer message can include a message header and message data. The message header may include the compression indicator field and the encryption indicator field, etc. The message data includes the aforementioned encrypted data.

[0170] Optionally, the Beidou network device 200 can also encrypt the compression instruction field together with the compressed data to obtain encrypted data.

[0171] At the MDCP layer, the BeiDou network device 200 can obtain application layer messages sent from the APP layer through the inter-layer interface and treat each application layer message as an MDCP SDU. At the MDCP layer, the BeiDou network device 200 can split an MDCP SDU into one or more fixed-length MDCP segments (M_segement) and add a successor indication field to the header of each MDCP segment to obtain an MDCP PDU. That is, an MDCP PDU includes an M_segement and a successor indication field. The successor indication field can be used to indicate whether the current MDCP PDU is the starting, middle, or last MDCP PDU of a series of consecutively sent MDCP PDUs; or it can be a single, independently sent MDCP PDU.

[0172] At the SLC layer, the BeiDou network device 200 can obtain the MDCP PDU issued by the MDCP layer through the inter-layer interface, and use it as the SLC SDU. At the SLC layer, the BeiDou network device 200 can segment the SLC SDU into one or more (e.g., up to four) fixed-length SLC segment data (S_segement), and add frame header information to the header of each S_segement to obtain the SLCPDU.

[0173] Here, it's understandable that the SLC layer needs to segment the data to accommodate the frame length of the physical layer. However, the SLC layer is designed so that a single SLC SDU can only be divided into a maximum of four SLC PDUs; therefore, the MDCP layer also needs to segment the data.

[0174] At the PHY layer, the BeiDou network device 200 can obtain SLC PDUs from the SLC layer through the inter-layer interface. The BeiDou network device 200 can obtain SLC PDUs from one or more users from the SLC layer. The BeiDou network device 200 can concatenate the SLC PDUs from multiple users, add the frame header (e.g., version number) of the physical frame as a code block for the PHY layer, add a check bit (e.g., cyclic redundancy check (CRC) code) to the end of the code block, and encode the code block and CRC code (e.g., polar encoding). The encoded physical frame, plus a reserved segment, can form the encoded data of a fixed-length physical time slot satellite-to-consumer data (S2C-d) channel (simply put, the data channel). The BeiDou network device 200 can also place multiple SLC PDUs from one user into different physical frames. Then, the BeiDou network device 200 combines the coded data from the S2C-d channel branch with the pilot information from the satellite-to-consumer pilot (S2C-p) channel (hereinafter referred to as the pilot channel) to form pilot coded data, i.e., outgoing data. The BeiDou network device 200 can send the outgoing data to the BeiDou short message satellite 21, which will then relay it to the terminal 100.

[0175] Understandably, the pilot information of the S2C_p channel branch is related to the satellite beam. When the satellite beam number is known, the pilot information (i.e., the subcode) of the S2C-p channel branch is also known and does not require decoding. However, the encoded data of the S2C_d channel branch requires decoding. The S2C-p and S2C-d channels have the same center frequency and bandwidth, and the signals on the S2C-p and S2C-d channels are orthogonal to each other.

[0176] The following describes a protocol parsing architecture for outbound data of a Beidou communication system 10 provided in the embodiments of this application.

[0177] Figure 8 This paper illustrates a schematic diagram of the protocol parsing architecture for outbound data of a Beidou communication system 10 provided in an embodiment of this application.

[0178] like Figure 8As shown, the BeiDou short message transmission protocol layer of terminal 100 can be divided into application layer protocol, message data convergence protocol (MDCP), satellite link control protocol (SLC) and physical layer protocol (PHY).

[0179] When terminal 100 receives data sent by BeiDou network equipment, the workflow of the BeiDou short message transmission protocol layer of terminal 100 can be as follows:

[0180] At the PHY layer, terminal 100 can obtain the modulated and spread-spectrum pilot coded data sent by BeiDou network device 200. Terminal 100 can despread the received spread-spectrum modulated data to obtain modulated data. Then, terminal 100 can demodulate the modulated data to obtain pilot coded data. Next, terminal 100 can remove the pilot information from the pilot coded data to obtain coded data. Then, terminal 100 can decode the coded data and verify the integrity of the code block through the check bit field. If complete, terminal 100 can extract the code block and present it to the SLC layer through the inter-layer interface as the SLC PDU of the SLC layer.

[0181] Here, the pilot coded data is the outgoing data sent by the Beidou network device 200 mentioned above. The outgoing data consists of the coded data of the S2C-d channel and the pilot information of the S2C-p channel.

[0182] At the SLC layer, terminal 100 can concatenate SLC PDUs belonging to the same SLC SDU into a single SLC SDU based on the frame header information of the SLC PDU. Terminal 100 can then present the SLC SDU to the MDCP layer through the inter-layer interface, serving as the MDCP PDU for the MDCP layer.

[0183] At the MDCP layer, terminal 100 can concatenate all MDCP PDUs belonging to the same MDCP SDU into a single MDCPSDU. Terminal 100 can then present the MDCP SDU to the APP layer through the inter-layer interface, serving as an application layer message received by the APP layer.

[0184] At the APP layer, terminal 100 can decrypt and decompress the application layer message based on the message header to obtain the original data.

[0185] In the embodiments of this application, the above protocol processing procedure is only an example for illustration, and this application does not limit the specific operation of protocol processing.

[0186] The following describes an outbound data transmission method in a BeiDou communication system provided in the embodiments of this application.

[0187] In some application scenarios, without connection state management and mobility management in the BeiDou communication system 10, the BeiDou network device 200 cannot actively page users. Therefore, before the terminal 100 receives service data sent by the BeiDou network device 200, the terminal 100 needs to actively send a data request frame to the BeiDou network device 200. The terminal 100 can determine the MCS used by the BeiDou network device 200 when sending service data to the terminal 100 by measuring the S2C-p pilot channel. The terminal 100 can carry an MCS indication field in the data request frame, which can be used to indicate the MCS that the terminal 100 suggests the BeiDou network device 200 use when sending service data to the terminal 100. In this way, without additional signaling overhead, the terminal 100 can feed back the outbound MCS to the BeiDou network device 200, improving channel utilization.

[0188] Figure 9 The illustration shows a flowchart of an outbound data transmission method in a BeiDou communication system according to an embodiment of this application.

[0189] like Figure 9 As shown, the method includes:

[0190] S901 and Beidou network equipment 200 transmit pilot information on the S2C-p channel.

[0191] Among them, the Beidou network equipment 200 can continuously transmit pilot information on the S2C-p channel. This pilot information is used by each terminal in the Beidou communication system to capture data signals on the S2C-d channel.

[0192] S902 and Terminal 100 measure the channel quality on the S2C-p channel and determine the channel quality on the S2C-d channel based on the channel quality on the S2C-p channel.

[0193] In this system, the pilot information transmitted by the BeiDou network device 200 on the S2C-p channel is a known subcode to the terminal 100. After receiving the pilot information, the terminal 100 can compare the subcode in the pilot information with the known subcode to determine the channel quality of the S2C-p channel. The channel quality may be measured, but is not limited to, by SNR (Short-Range Radio Frequency).

[0194] Since the S2C-p channel and the S2C-d channel have the same center frequency and bandwidth, the signals on the S2C-p channel and the signals on the S2C-d channel are orthogonal to each other. Furthermore, the transmission power of the BeiDou network device 200 transmitting pilot information on the S2C-p channel differs from the transmission power of transmitting data information on the S2C-d channel, but this difference is generally a fixed value. Therefore, after measuring the channel quality on the S2C-p channel, the terminal 100 can calculate the channel quality on the S2C-d channel based on the channel quality on the S2C-p channel.

[0195] Among them, the SNR of the outgoing S2C-d channel of the Beidou network equipment 200 can be determined based on the following formula (1):

[0196] SNR d =SNR p +δ formula (1)

[0197] In the above formula (1), SNR d SNR of the S2C-d channel p denoted as SNR of the S2C-p channel, and δ as the channel quality difference between the S2C-d and S2C-p channels.

[0198] S903 and Terminal 100 determine the first modulation and coding scheme (MCS) based on the channel quality on the S2C-d channel.

[0199] Terminal 100 can determine the first MCS based on the SNR of the S2C-d channel from the SNR-MCS mapping table. This SNR-MCS mapping table can be obtained through physical layer simulation in the BeiDou communication system. A higher SNR corresponds to a higher order of MCS.

[0200] For example, the mapping table between SNR and MCS can be shown in Table 1 below:

[0201] Table 1

[0202]

[0203] As shown in Table 1 above, when -5dB < SNR ≤ 0dB, it corresponds to a 0th-order MCS, i.e., BPSK and 1 / 2 bit rate. When 0dB < SNR ≤ 5dB, it corresponds to a 1st-order MCS, i.e., BPSK and 3 / 4 bit rate. When 5dB < SNR ≤ 11dB, it corresponds to a 2nd-order MCS, i.e., QPSK and 1 / 2 bit rate. When 11dB < SNR ≤ 12dB, it corresponds to a 3rd-order MCS, i.e., QPSK and 3 / 4 bit rate. When 12dB < SNR ≤ 17.5dB, it corresponds to a 4th-order MCS, i.e., 16QAM and 1 / 2 bit rate. When 17.5dB < SNR ≤ 22.5dB, it corresponds to a 5th-order MCS, i.e., 16QAM and 3 / 4 bit rate. When 22.5dB < SNR, it corresponds to a 6th-order MCS, i.e., 64QAM and 3 / 4 bit rate. Table 1 above is only used to explain this application and should not be construed as limiting it. The mapping table of SNR and MCS may include fewer or more mapping relationships between SNR and MCS.

[0204] For example, when terminal 100 measures the SNR on the S2C-d channel to be 10dB, terminal 100 can determine the first MCS as QPSK and 1 / 2 code rate based on the SNR-MCS mapping table shown in Table 1 above.

[0205] S904. Terminal 100 sends a data request frame to BeiDou network device 200. The header of this data request frame includes an MCS indication field, which indicates the first MCS. This data request frame requests BeiDou network device 200 to send service data to terminal 100.

[0206] Specifically, in BeiDou network equipment 200, data request frames can include mailbox overview query frames and email download frames. The frame format of the data request frame can be found in [reference needed]. Figure 10A .

[0207] like Figure 10A As shown, an incoming physical frame may include a synchronization header, a data segment, and a check bit. The synchronization header distinguishes the frame type of the incoming physical frame, and its duration can be 40ms. Frame types may include location reporting frames, emergency rescue frames, and message communication frames. When the incoming physical frame is a message communication frame, the value of the synchronization header indicates that it is a message communication frame. The check bit is used to verify the integrity of the data in the data segment. In the BeiDou communication system, Cyclic Redundancy Check (CRC) can be used to verify the data segment, and this check bit may include a CRC checksum.

[0208] This data segment may include user frames, which may include frame header information and user information. The frame header information may include a version number field, a subtype indicator field, a user ID field, an MCS indicator field, and a reserve (RSV) field. The version number field indicates the protocol format version of the user frame. The subtype indicator field indicates the subtype of the user frame, which may include general data frames, ACK frames, and acknowledgment frames, etc. The user ID field indicates the device identifier of terminal 100. The MCS indicator field indicates the first MCS recommended by terminal 100 for BeiDou network device 200.

[0209] For example, when the BeiDou network device 200 uses three different MCS types, the data length of the MCS indicator field can be 2 bits. The values ​​and meanings of the MCS indicator field are shown in Table 2 below:

[0210] Table 2

[0211] MCS indicates the value of the field MCS 00 NA 01 MCS0 10 MCS1 11 MCS2

[0212] As shown in Table 2 above, if the BeiDou network device 200 uses three different MCSs, the value "00" in the MCS indicator field is an invalid (NA) value, used to instruct the BeiDou network device 200 to select an MCS (for example, by default, selecting the MCS with the lowest order). The value "01" in the MCS indicator field corresponds to MCS0 (order 0 MCS). The value "10" in the MCS indicator field corresponds to MCS1 (order 1 MCS). The value "11" in the MCS indicator field corresponds to MCS2 (order 2 MCS). For example, MCS0 can be BPSK with a 3 / 4 code rate, MCS1 can be QPSK with a 1 / 2 code rate, and MCS2 can be QPSK with a 3 / 4 code rate. The examples shown in Table 2 above are merely for illustrative purposes and should not be construed as limiting the scope of this application.

[0213] In practice, the types of MCS used by the BeiDou network device 200 are not limited to three; they can be fewer or more. The data length of the MCS indicator field can also vary based on the number of MCS types used by the BeiDou network device 200. For example, when the BeiDou network device 200 uses five types of MCS, the data length of the MCS indicator field can be 3 bits.

[0214] User information may include application-layer messages. These messages may include a header and data. The header may include a service type field, an encryption indicator field, and a compression indicator field. The service type field indicates the service type of the application-layer message. Service types may include mailbox overview query service, mail download service, and communication message service.

[0215] When the service type of the application layer message is mailbox overview query service, the message data can carry the query information of terminal 100. The query information includes the time of the query by terminal 100, the number of messages sent to terminal 100 by the specified user, etc.

[0216] When the service type of the application layer message is a letter download service, the message data can carry an identifier of the letter message that the terminal 100 requests the Beidou network device 200 to send.

[0217] S905 and Beidou network equipment 200 respond to the data request frame and generate the first application layer message.

[0218] Specifically, after receiving a data request frame, the Beidou network device 200 can parse the application layer message from the data request frame and distinguish the service type of the data request frame from the service type indication field of the application layer service message.

[0219] If the service type of the data request frame is mailbox overview query service, the terminal 100 generates the first application layer message based on the query information.

[0220] If the service type of the data request frame is a mail download service, the terminal 100 parses the message identifier sent by the BeiDou network device 200, which is requested by the terminal 100, carried in the message data of the data request frame. Based on the message identifier sent by the BeiDou network device 200, the BeiDou network device 200 can determine the first message from the mailbox of the terminal 100 and generate the first application layer message based on the first message.

[0221] S906 and Beidou network equipment 200 split the first application layer message into one or more user frames, and the one or more user frames include the second user frame.

[0222] The second user frame can be any one of the user frames in one or more of the first application layer message.

[0223] Specifically, regarding the process by which BeiDou network equipment 200 splits the first application layer message into multiple user frames, please refer to the aforementioned... Figure 7 The protocol encapsulation process for application layer messages in the illustrated embodiment will not be described in detail here.

[0224] After receiving a data request frame, the S907 and Beidou network equipment 200 can determine the outgoing MCS based on the first MCS indicated by the MCS indication field in the data request frame.

[0225] S908 and Beidou network equipment 200 place the second user frame into the first physical frame and encode and modulate the first physical frame based on the outgoing MCS.

[0226] In one possible implementation, the outgoing MCS is the same as the first MCS. The BeiDou network device 200 directly uses the first MCS indicated by the terminal 100 in the MCS indication field to encode and modulate the first physical frame.

[0227] In one possible implementation, the BeiDou network device 200 can determine the outbound MCS based on the actual outbound traffic volume and the first MCS. For example, terminal 400 instructs the BeiDou network device 200 to send service data to terminal 400 using the MCS indication field in the inbound user frame. The BeiDou network device 200 can schedule the fifth user frame of terminal 400 and the second user frame of terminal 100 into the first physical frame. If the order of the fifth MCS is less than the order of the first MCS, the BeiDou network device 200 can use the fifth MCS to encode and modulate the first physical frame. If the order of the fifth MCS is greater than or equal to the order of the first MCS, the BeiDou network device 200 can use the first MCS to encode and modulate the first physical frame.

[0228] For example, terminal 100 can instruct BeiDou network device 200 to send service data to terminal 100 using MCS1 (e.g., QPSK and 1 / 2 code rate) through the MCS indication field. Terminal 400 can instruct BeiDou network device 200 to send service data to terminal 400 using MCS2 (QPSK and 3 / 4 code rate) through the MCS indication field in the message request. When BeiDou network device 200 schedules both user frame A of terminal 100 and user frame B of terminal 400 into the same outbound physical frame, BeiDou network device 200 can send the physical frame containing user frame 1 and user frame 2 using MCS1 (e.g., QPSK and 1 / 2 code rate).

[0229] For example, terminal 100 can instruct BeiDou network device 200 to send service data to terminal 100 using MCS1 (e.g., QPSK and 1 / 2 code rate) through the MCS indication field. Terminal 400 can instruct BeiDou network device 200 to send service data to terminal 400 using MCS2 (QPSK and 3 / 4 code rate) through the MCS indication field in the message request. When BeiDou network device 200 schedules both user frame 1 of terminal 100 and user frame 2 of terminal 400 into a single outgoing physical frame, BeiDou network device 200 can send the physical frame containing user frame 1 and user frame 2 using MCS1 (e.g., QPSK and 1 / 2 code rate).

[0230] In this way, when multiple terminals in the same outgoing physical frame have inconsistent MCSs, the BeiDou network device 200 can use the MCS with the smallest order among the multiple terminals to send the outgoing physical frame, so as to ensure that all terminals can parse their respective user frames from the outgoing physical frame.

[0231] In one possible implementation, terminal 400 instructs BeiDou network device 200 to send service data to terminal 400 using the fifth MCS (Multi-Channel Code). BeiDou network device 200 can schedule the fifth user frame from terminal 400 and the second user frame from terminal 100 into the first physical frame. If the order of the fifth MCS is less than the order of the first MCS, BeiDou network device 200 can use the first MCS to encode and modulate the first physical frame. If the order of the fifth MCS is greater than or equal to the order of the first MCS, BeiDou network device 200 can use the fifth MCS to encode and modulate the first physical frame. Thus, when user frames from multiple terminals are scheduled into the same outgoing physical frame, and the MCSs indicated by the multiple terminals are inconsistent, BeiDou network device 200 can use the MCS with the highest order among the MCSs indicated by the multiple terminals to send the outgoing physical frame, thereby improving transmission capacity.

[0232] In some embodiments, when scheduling the transmission of user frames from multiple terminals, the BeiDou network device 200 can schedule user frames from terminals with the same type of outbound channel quality into the same physical frame.

[0233] For example, such as Figure 10B As shown, the user frames that the BeiDou network device 200 needs to schedule for transmission include user frame 1, user frame 2, user frame 3, user frame 4, user frame 5, and user frame 6. User frames 1, 2, 3, and 4 require modulation and coding scheme 1 (MCS-1). User frames 5 and 6 require modulation and coding scheme 2 (MCS-2). Due to the limited time length of the outgoing physical frame, the amount of data that can be contained in the outgoing physical frame is limited, and therefore the number of user frames that can be contained in the outgoing physical frame is also limited. The scheduler of the BeiDou network device 200 can schedule user frames 1 and 2 into physical frame 1 and use MCS-1 to encode and modulate physical frame 1. The scheduler of the BeiDou network device 200 can schedule user frames 5 and 6 into physical frame 2 and use MCS-2 to encode and modulate physical frame 1. The scheduler of the BeiDou network device 200 can schedule user frames 3 and 4 into physical frame 3 and use MCS-1 to encode and modulate physical frame 3. The above examples are merely for explaining this application and should not be construed as limiting it.

[0234] In one possible implementation, the BeiDou network device 200 can prioritize scheduling user frames with high MCS bit rates.

[0235] In one possible implementation, the BeiDou network device 200 can put user frames from multiple terminals with the same modulation scheme but different bit rates in the MCS into a single physical frame, and transmit the physical frame using the low bit rate in the MCS indicated by the multiple terminals.

[0236] In the embodiments of this application, the execution order of step S907 is after step S904 and before step S908. It is not limited to after steps S905-S906, but can also be before step S905 or between step S905 and step S906.

[0237] S909 and Beidou network equipment 200 transmit the first outgoing data. This first outgoing data includes pilot information from the S2C-p channel and the first physical frame coded and modulated on the S2C-d channel.

[0238] After receiving the first outgoing data sent by the Beidou network device 200, S910 and terminal 100 parse the second user frame of terminal 100 from the first outgoing data.

[0239] Specifically, terminal 100 can demodulate and decode the received first outbound data using the first MCS determined above. If decoding is successful, terminal 100 can parse its second user frame from the first physical frame.

[0240] If terminal 100 fails to decode, terminal 100 can traverse other MCSs to decode the first outgoing data until decoding is successful.

[0241] Specifically, the process by which terminal 100 decodes the first outgoing data can be as follows:

[0242] Terminal 100 demodulates and decodes the data from the second outgoing station via the selected MCS. If the checksum calculated by terminal 100 based on the data segment in the decoded physical frame is the same as the value of the checksum field in the decoded physical frame, then terminal 100 determines that decoding is successful. If the checksum calculated by terminal 100 based on the data segment in the decoded physical frame is different from the value of the checksum field in the decoded physical frame, then terminal 100 determines that decoding has failed.

[0243] The outbound data transmission method in the BeiDou communication system provided in this application embodiment enables terminal 100 to determine the first MCS by measuring the channel quality of the S2C-p channel in the outbound data, and to instruct BeiDou network device 200 to encode and modulate the service data to be sent to terminal 100 using the first MCS indicated in the MCS indication field by carrying an MCS indication field in the data request frame. In this way, terminal 100 can feed back the outbound MCS to BeiDou network device 200 without additional signaling overhead, thereby improving channel utilization.

[0244] In some application scenarios, BeiDou network device 200 can send user frames to terminal 100 using an acknowledgment mode. After receiving the user frames sent by BeiDou network device 200, terminal 100 can return an ACK to BeiDou network device 200. This ACK indicates the reception status of the user frames. Therefore, when parsing the user frames sent by BeiDou network device 200, terminal 100 can determine the MCS used by BeiDou network device 200 when sending service data to terminal 100 by measuring the channel quality on the S2C-d channel. When returning the ACK to BeiDou network device 200, terminal 100 can include an MCS indication field. This MCS indication field can be used to indicate the MCS used by BeiDou network device 200 when sending service data to terminal 100. In this way, without additional signaling overhead, terminal 100 can complete the feedback of the outbound MCS to BeiDou network device 200, improving channel utilization.

[0245] Figure 11 The illustration shows a flowchart of an outbound data transmission method in a BeiDou communication system according to an embodiment of this application.

[0246] like Figure 11 As shown, the method includes:

[0247] S1101, Beidou network equipment 200 puts the third user frame of terminal 100 into the second physical frame, and encodes and modulates the second physical frame based on the third MCS.

[0248] When the third user frame is the first SLC PDU in the application layer message, the third MCS can be the MCS with the lowest order among the MCSs supported on the Beidou network device 200.

[0249] S1102, Beidou network equipment 200 sends the second outgoing data, which includes pilot information of the S2C-p channel and the second physical frame of the S2C-d channel after coding and modulation.

[0250] S1103, Terminal 100 parses the third user frame of Terminal 100 from the second outgoing data.

[0251] The terminal 100 may have a pre-configured third MCS, which allows it to demodulate and decode the received first outgoing data. If decoding is successful, the terminal 100 can parse its third user frame from the second physical frame.

[0252] If terminal 100 fails to decode the second outgoing data based on the third MCS, terminal 100 can traverse other MCSs to demodulate and decode the second outgoing data until decoding is successful.

[0253] S1104, Terminal 100 determines the first MCS based on the channel quality on the S2C-d channel.

[0254] After decoding the first user frame from the first outgoing data, the terminal 100 can complete the channel quality assessment on the S2C-d channel. The channel quality can be measured by SNR, among other things.

[0255] Terminal 100 can determine the first MCS based on the SNR of the S2C-d channel from the SNR-MCS mapping table. This SNR-MCS mapping table can be obtained through physical layer simulation in the BeiDou communication system. For example, the SNR-MCS mapping table can refer to the above-described... Figure 9 Table 1 in the illustrated embodiment will not be repeated here.

[0256] S1105, Terminal 100 sends an ACK to BeiDou network device 200. This ACK indicates the reception status of the third user frame by Terminal 100. The ACK carries an MCS indication field, which indicates the first MCS.

[0257] The frame format for ACK can be found in [reference]. Figure 12A or Figure 12B The frame format of the inbound ACK frame shown is as follows:

[0258] 1. For example Figure 12A As shown, the frame format of an incoming physical frame can include a synchronization header, a data segment, and a checksum. The synchronization header distinguishes the frame type of the incoming physical frame, and its duration can be 40ms. Frame types of incoming physical frames can include location reporting frames, emergency rescue frames, and message communication frames. When the incoming physical frame is a message communication frame, the value of the synchronization header indicates that it is a message communication frame. The checksum is used to verify the integrity of the data in the data segment. In the BeiDou communication system, Cyclic Redundancy Check (CRC) can be used to verify the data segment, and this checksum can include a CRC checksum.

[0259] This data segment may include user frames, which may include frame header information and user information. The frame header information may include a version number field, a subtype indicator field, a user ID field, an MCS indicator field, and a reserve (RSV) field. The version number field indicates the protocol format version of the user frame. The subtype indicator field indicates the subtype of the user frame, which may include general data frames, ACK frames, and acknowledgment frames, etc. Specifically, the value of the subtype indicator field for the inbound ACK frame indicates that the subtype is an ACK frame. The user ID field indicates the device identifier of terminal 100. The MCS indicator field indicates the fourth MCS recommended by terminal 100 for BeiDou network device 200.

[0260] The user information in an inbound ACK frame may include an ACK field and padding data. The ACK field can be 1 bit, and the padding data can be used to fill the inbound ACK frame to a specified data length to meet the requirement that inbound physical frames have a fixed data length. Specifically, the ACK field can be used to indicate whether terminal 100 has received the SLC PDU sent to terminal 100 by BeiDou network device 200. For example, a value of "0" in the ACK field indicates that terminal 100 has not received the SLC PDU sent to terminal 100 by BeiDou network device 200. A value of "1" in the ACK field indicates that terminal 100 has received the SLC PDU sent to terminal 100 by BeiDou network device 200.

[0261] For example, when the BeiDou network device 200 uses three different MCS types, the data length of the MCS indicator field can be 2 bits. The values ​​and meanings of the MCS indicator field are shown in Table 3 below:

[0262] Table 3

[0263] MCS indicates the value of the field MCS 00 NA 01 MCS0 10 MCS1 11 MCS2

[0264] As shown in Table 3 above, if the BeiDou network device 200 uses three different MCSs, the value "00" in the MCS indicator field is an invalid (NA) value. The value "01" in the MCS indicator field corresponds to MCS0 (0th-order MCS). The value "10" in the MCS indicator field corresponds to MCS1 (1st-order MCS). The value "11" in the MCS indicator field corresponds to MCS2 (2nd-order MCS). For example, MCS0 can be BPSK with a 3 / 4 code rate, MCS1 can be QPSK with a 1 / 2 code rate, and MCS2 can be QPSK with a 3 / 4 code rate. The examples shown in Table 3 are merely for illustrative purposes and should not be construed as limiting the scope of this application.

[0265] In practice, the types of MCS used by the BeiDou network device 200 are not limited to three; they can be fewer or more. The data length of the MCS indicator field can also vary based on the number of MCS types used by the BeiDou network device 200. For example, when the BeiDou network device 200 uses five types of MCS, the data length of the MCS indicator field can be 3 bits.

[0266] For example, the data length of the MCS indicator field can be fixed at 2 bits. The values ​​and meanings of the MCS indicator field are shown in Table 4 below:

[0267] Table 4

[0268] MCS indicates the value of the field MCS 00 NA 01 constant 10 Increase MCS order 11 Reduce MCS order

[0269] As shown in Table 4 above, if the BeiDou network device 200 uses three different MCSs, the value "00" in the MCS indicator field is an invalid (NA) value. A value "01" in the MCS indicator field indicates that the BeiDou network device 200 continues to use the third MCS used when encoding and modulating the aforementioned physical frame A to encode and modulate subsequent user frames of the terminal 100; that is, the first MCS is the same as the third MCS. A value "10" in the MCS indicator field indicates that the BeiDou network device 200 uses the first MCS obtained by increasing the order (e.g., increasing by one order) based on the third MCS used when encoding and modulating physical frame A, to encode and modulate subsequent user frames of the terminal 100. A value "11" in the MCS indicator field indicates that the BeiDou network device 200 uses the first MCS obtained by decreasing the order (e.g., decreasing by one order) based on the third MCS used when encoding and modulating physical frame A, to encode and modulate subsequent user frames of the terminal 100. The examples shown in Table 4 above are merely for explaining this application and should not be construed as limiting it.

[0270] In some embodiments, where the data length of the MCS indication field can be fixed at 2 bits, if the number of MCS order types supported by the BeiDou network device 200 is less than or equal to 3, the terminal 100 may preferentially use the feedback mode shown in Table 3 above to feed back MCS information to the BeiDou network device 200 through the MCS indication field in the ACK frame. If the number of MCS end types supported by the BeiDou network device 200 is greater than 3, the terminal 100 may preferentially use the feedback mode shown in Table 4 above to feed back MCS information to the BeiDou network device 200 through the MCS indication field in the ACK frame.

[0271] 2. For example Figure 12BAs shown, the frame format of an incoming physical frame can include a synchronization header, a data segment, and a checksum. The synchronization header distinguishes the frame type of the incoming physical frame, and its duration can be 40ms. Frame types of incoming physical frames can include location reporting frames, emergency rescue frames, and message communication frames. When the incoming physical frame is a message communication frame, the value of the synchronization header indicates that it is a message communication frame. The checksum is used to verify the integrity of the data in the data segment. In the BeiDou communication system, Cyclic Redundancy Check (CRC) can be used to verify the data segment, and this checksum can include a CRC checksum.

[0272] This data segment may include user frames, which may include frame header information and user information. The frame header information may include a version number field, a subtype indicator field, a user ID field, and a reserved (RSV) field. The version number field indicates the protocol format version of the user frame. The subtype indicator field indicates the subtype of the user frame, which may include general data frames, ACK frames, and acknowledgment frames, etc. Specifically, the value of the subtype indicator field for this inbound ACK frame indicates that the subtype is an ACK frame. The user ID field indicates the device identifier of terminal 100.

[0273] The user information in the inbound ACK frame may include an ACK field and padding data. The ACK field may include an MCS indicator field, which can be 2 bits. Padding data can be used to fill the inbound ACK frame to a specified data length to meet the requirement that inbound physical frames have a fixed data length. Since the ACK field includes an MCS indicator field, this field can be used to indicate whether terminal 100 has received the SLC PDU of the SLC layer sent to terminal 100 by BeiDou network device 200. If the ACK field indicates that terminal 100 has received the SLC PDU of the SLC layer sent to terminal 100 by BeiDou network device 200, the ACK field can also indicate the first MCS recommended by terminal 100 to BeiDou network device 200.

[0274] For example, when the BeiDou network device 200 uses three different MCS types, the data length of the ACK field can be 2 bits. The values ​​of the ACK field and their meanings are shown in Table 5 below:

[0275] Table 5

[0276] The value of the ACK field MCS 00 NACK 01 MCS0 10 MCS1 11 MCS2

[0277] As can be seen from Table 5 above, there are three types of MCS used by Beidou network equipment 200.

[0278] 1. When terminal 100 adopts the single-frame feedback mode, after receiving a single SLC PDU frame sent by BeiDou network device 200, terminal 100 can return an ACK to BeiDou network device 200. Among other things,

[0279] When the value of the ACK field is “00”, it is “NACK”, which indicates that the terminal 100 has not received the previous SLC PDU (i.e., user frame A) sent by the Beidou network device 200.

[0280] The value of the ACK field is "01", which indicates that the terminal 100 has received the previous SLCPDU (i.e., user frame A) sent by the Beidou network device 200, and indicates that the Beidou network device 200 uses MCS0 (0th order MCS) for coding and modulation when sending the next SLCPDU (i.e., user frame B).

[0281] The value of the ACK field is "10", which indicates that the terminal 100 has received the previous SLCPDU (i.e., user frame A) sent by the Beidou network device 200, and indicates that the Beidou network device 200 uses MCS1 (first-order MCS) for encoding and modulation when sending the next SLCPDU (i.e., user frame B).

[0282] The value of the ACK field is "11", indicating that terminal 100 has received the previous SLCPDU (i.e., user frame A) sent by BeiDou network device 200, and instructing BeiDou network device 200 to use MCS2 (second-order MCS) for coding and modulation when sending the next SLCPDU (i.e., user frame B). For example, MCS0 can be BPSK with a 3 / 4 code rate, MCS1 can be QPSK with a 1 / 2 code rate, and MCS2 can be QPSK with a 3 / 4 code rate. The examples shown in Table 5 above are only for explaining this application and should not be construed as limiting it.

[0283] 2. When terminal 100 adopts the multi-frame feedback mode, after receiving a set (N, for example, N can be 4) of SLC PDUs sent by BeiDou network device 200, terminal 100 can return an ACK to BeiDou network device 200. Among these,

[0284] When the value of the ACK field is “00”, it is “NACK”, which indicates that the terminal 100 has not received a complete set (N) of SLC PDUs sent by the Beidou network device 200.

[0285] The value of the ACK field is "01", which indicates that the terminal 100 has received all the previous set of SLC PDUs sent by the Beidou network device 200, and indicates that the Beidou network device 200 uses MCS0 (0th order MCS) for encoding and modulation when sending the next set of SLC PDUs.

[0286] The value of the ACK field is "10", which indicates that the terminal 100 has received all the previous set of SLC PDUs (i.e., user frame A) sent by the Beidou network device 200, and indicates that the Beidou network device 200 uses MCS1 (first-order MCS) for coding and modulation when sending the next set of SLC PDUs.

[0287] The ACK field value of "11" indicates that terminal 100 has received all of the previous SLC PDU (i.e., user frame A) sent by BeiDou network device 200, and instructs BeiDou network device 200 to use MCS2 (second-order MCS) for coding and modulation when sending the next SLC PDU. For example, MCS0 can be BPSK with a 3 / 4 code rate, MCS1 can be QPSK with a 1 / 2 code rate, and MCS2 can be QPSK with a 3 / 4 code rate. The examples shown in Table 5 above are only for explaining this application and should not be construed as limiting it.

[0288] In practice, the types of MCS used by the BeiDou network device 200 are not limited to three; they can be fewer or more. The data length of the ACK field can also vary based on the number of MCS types used by the BeiDou network device 200. For example, when the BeiDou network device 200 uses five types of MCS, the data length of the MCS indicator field can be 3 bits.

[0289] For example, the data length of the ACK field can be fixed at 2 bits. The values ​​of the ACK field and their meanings are shown in Table 6 below:

[0290] Table 6

[0291] The value of the ACK field MCS 00 NACK 01 constant 10 Increase MCS order 11 Reduce MCS order

[0292] As can be seen from Table 6 above, if the BeiDou network equipment 200 uses a total of 3 types of MCS:

[0293] The value of the ACK field is "00", which is "NACK" and is used to indicate that the terminal 100 has not received the previous SLC PDU (i.e., user frame A) sent by the Beidou network device 200.

[0294] The value of the ACK field is "01", which indicates that the terminal 100 has received the previous SLCPDU (i.e., user frame A) sent by the Beidou network device 200, and the Beidou network device 200 continues to use the third MCS used when encoding and modulating the above physical frame A to encode and modulate the subsequent SLC PDU (i.e., user frame B) of the terminal 100, that is, the first MCS is the same as the third MCS.

[0295] The value of the ACK field is "10", which indicates that the terminal 100 has received the previous SLCPDU (i.e., user frame A) sent by the Beidou network device 200, and that the Beidou network device 200 has obtained the first MCS by adding an order (e.g., adding 1 order) to the third MCS used when encoding and modulating physical frame A, and then encodes and modulates the subsequent SLC PDU (i.e., user frame B) of the terminal 100.

[0296] The value of the ACK field is "11", which indicates that the terminal 100 has received the previous SLCPDU (i.e., user frame A) sent by the Beidou network device 200, and that the Beidou network device 200 has obtained the first MCS by reducing the order (e.g., reducing one order) based on the third MCS used when encoding and modulating physical frame A, and then encodes and modulates the subsequent SLC PDU (i.e., user frame B) of the terminal 100.

[0297] The examples shown in Table 6 above are for illustrative purposes only and should not be construed as limiting the scope of this application.

[0298] In some embodiments, where the data length of the ACK field can be fixed at 2 bits, if the number of MCS order types supported by the BeiDou network device 200 is less than or equal to 3, the terminal 100 may preferentially use the feedback mode shown in Table 5 above to feed back MCS information to the BeiDou network device 200 through the ACK field in the ACK frame. If the number of MCS order types supported by the BeiDou network device 200 is greater than 3, the terminal 100 may preferentially use the feedback mode shown in Table 6 above to feed back MCS information to the BeiDou network device 200 through the ACK field in the ACK frame.

[0299] After receiving the first ACK, S1106 and Beidou network equipment 200 determine the outgoing MCS based on the first MCS indicated in the MCS indication field of the first ACK.

[0300] In one possible implementation, the outgoing MCS is the same as the first MCS, and the BeiDou network device 200 can directly use the first MCS indicated by the terminal 100 in the MCS indication field to encode and modulate the physical frame.

[0301] In one possible implementation, the BeiDou network device 200 can determine the outgoing / outgoing MCS based on the actual outgoing traffic volume and the first MCS. For example, terminal 400 instructs the BeiDou network device 200 to send service data to terminal 400 using the fifth MCS via the MCS indication field. The BeiDou network device 200 can schedule the fifth user frame of terminal 400 and the second user frame of terminal 100 into the first physical frame. If the order of the fifth MCS is less than the order of the first MCS, the BeiDou network device 200 can use the fifth MCS to encode and modulate the first physical frame. If the order of the fifth MCS is greater than or equal to the order of the first MCS, the BeiDou network device 200 can use the first MCS to encode and modulate the first physical frame.

[0302] For example, terminal 100 can instruct BeiDou network device 200 to send service data to terminal 100 using MCS1 (e.g., QPSK and 1 / 2 code rate) through the MCS indication field. Terminal 400 can instruct BeiDou network device 200 to send service data to terminal 400 using MCS2 (QPSK and 3 / 4 code rate) through the MCS indication field in the message download request frame. When BeiDou network device 200 schedules both user frame B of terminal 100 and user frame 3 of terminal 400 into the same outbound physical frame, BeiDou network device 200 can send the physical frame B containing user frame B and user frame 3 using MCS1 (e.g., QPSK and 1 / 2 code rate).

[0303] For example, terminal 100 can instruct BeiDou network device 200 to send service data to terminal 100 using MCS1 (e.g., QPSK and 1 / 2 code rate) through the MCS indication field. Terminal 400 can instruct BeiDou network device 200 to send service data to terminal 400 using MCS2 (QPSK and 3 / 4 code rate) through the MCS indication field in the message download request frame. When BeiDou network device 200 schedules both user frame B of terminal 100 and user frame 3 of terminal 400 into the same outbound physical frame, BeiDou network device 200 can send the physical frame B containing user frame B and user frame 3 using MCS1 (e.g., QPSK and 1 / 2 code rate).

[0304] In this way, when multiple terminals in the same outgoing physical frame have inconsistent MCSs when user frames are scheduled to be sent outgoing physical frames, the BeiDou network device 200 can use the MCS with the smallest order among the multiple terminals to send the outgoing physical frame, so as to ensure that these multiple terminals can parse their respective user frames from the outgoing physical frame.

[0305] In this embodiment of the application, terminal 100 may be referred to as the first terminal, and terminal 400 may be referred to as the second terminal.

[0306] S1107, the Beidou network equipment 200 puts the second user frame to be sent to the terminal 100 into the first physical frame, and encodes and modulates the first physical frame based on the outgoing MCS.

[0307] S1108, Beidou network equipment 200 transmits the first outgoing data. The first outgoing data includes pilot information of the S2C-p channel and the first physical frame coded and modulated on the S2C-d channel.

[0308] S1109, Terminal 100 parses the second user frame of Terminal 100 from the first outgoing data.

[0309] Specifically, terminal 100 can demodulate and decode the received first outbound data using the first MCS determined above. If decoding is successful, terminal 100 can parse its second user frame from the first physical frame.

[0310] If terminal 100 fails to decode, terminal 100 can traverse other MCSs to decode the first outgoing data until decoding is successful.

[0311] Specifically, the process by which terminal 100 decodes the first outgoing data can be as follows:

[0312] Terminal 100 demodulates and decodes the first outgoing data using the selected MCS. If the checksum calculated by terminal 100 based on the data segment in the decoded physical frame is the same as the value of the checksum field in the decoded physical frame, then terminal 100 determines that the decoding was successful, and the MCS used by terminal 100 for successful decoding is the outgoing MCS used by BeiDou network device 200. If the checksum calculated by terminal 100 based on the data segment in the decoded physical frame is different from the value of the checksum field in the decoded physical frame, then terminal 100 determines that the decoding failed.

[0313] The outbound data transmission method in the BeiDou communication system provided in this application embodiment enables terminal 100 to determine the MCS used by BeiDou network device 200 when sending service data to terminal 100 by measuring the channel quality on the S2C-d channel after parsing the third user frame sent by BeiDou network device 200. When returning an ACK to BeiDou network device 200, terminal 100 can include an MCS indication field in the ACK. This MCS indication field can be used to indicate the MCS used by BeiDou network device 200 when sending service data to terminal 100. In this way, without additional signaling overhead, terminal 100 can complete the feedback of the outbound MCS to BeiDou network device 200, improving channel utilization.

[0314] In some embodiments, the above Figure 9 The illustrated embodiment can be compared with Figure 13The illustrated embodiments are implemented in combination.

[0315] Before terminal 100 requests BeiDou network device 200 to send data, terminal 100 can determine the first MCS by measuring the channel quality of the S2C-p channel, and send the first MCS to BeiDou network device 200 via the first MCS indication field of the data request frame. This instructs BeiDou network device 200 to use the first MCS for coding and modulation when sending the first outgoing user frame of service data to terminal 100. After terminal 100 receives the first or intermediate outgoing user frame of service data, it can measure the channel quality on the S2C-d channel and determine the fourth MCS based on the channel quality. This fourth MCS is then sent to BeiDou network device 200 via the second MCS indication field of the ACK frame. This instructs BeiDou network device 200 to use the fourth MCS for coding and modulation when sending the next user frame of requested service data to terminal 100.

[0316] The specific process is as follows:

[0317] 1. Before sending a data request frame to the BeiDou network device 200, the terminal 100 can measure the channel quality of the BeiDou network device 200 on the S2C-p channel and determine the first MCS based on the channel quality on the S2C-p channel.

[0318] 2. Terminal 100 can send a data request frame to Beidou network device 200. The header information of the data request frame carries an MCS indication field, which is used to indicate the first MCS.

[0319] 3. Beidou Network Equipment 200: After receiving a data request frame, Beidou Network Equipment 200 can generate a first application layer message and split the first application layer message into multiple user frames. The multiple user frames include a second user frame and a fourth user frame. The second user frame is the first user frame among the multiple user frames, and the fourth user frame is not the first user frame among the multiple user frames.

[0320] 4. The Beidou network device 200 puts the second user frame into the first physical frame and encodes and modulates the first physical frame by using the outgoing MCS determined based on the first MCS.

[0321] 5. The Beidou network device 200 sends the first outgoing data, which includes pilot information of the S2C-p channel and the first physical frame of the S2C-d channel after coding and modulation.

[0322] 6. After receiving the first outbound data, the terminal 100 can parse the second user frame of the terminal 100 based on the first outbound data.

[0323] 7. After receiving user frame A (the first user frame or a non-first user frame), terminal 100 determines the fourth MCS by measuring the channel quality of the S2C-d channel and sends the first ACK to Beidou network device 200. The first ACK carries the second MCS indication field to indicate the fourth MCS.

[0324] 8. After receiving the first ACK, the Beidou network device 200 can determine the outgoing MCS based on the fourth MCS.

[0325] 9. The Beidou network device 200 can put the next user frame (e.g., the fourth user frame) of the terminal 100 into the third physical frame, and use the outgoing MCS determined based on the fourth MCS to encode and modulate the third physical frame.

[0326] 10. The Beidou network device 200 sends the third outgoing data to the terminal 100. The third outgoing data includes pilot information of the S2C-p channel and the third physical frame of the S2C-d channel after coding and modulation.

[0327] 11. Terminal 100 preferentially uses the fourth MCS to parse the fourth user frame of terminal 100 from the third outbound data.

[0328] When the Beidou network device 200 sends subsequent user frames of the service data requested by the terminal 100, the terminal 100 can repeatedly execute the above steps 7-11.

[0329] For details regarding steps 1-11 above, please refer to the aforementioned... Figure 9 and Figure 11 The contents of the illustrated embodiments will not be repeated here.

[0330] In some application scenarios, the BeiDou network device 200 may not receive channel quality feedback from the terminal 100. For example, when the BeiDou network device 200 sends user frames to the terminal 100 in unacknowledged mode, the terminal 100 does not return an ACK after receiving the user frame, and the BeiDou network device 200 cannot obtain the channel quality or MCS feedback from the terminal 100. Therefore, the BeiDou network device 200 can measure the inbound channel quality based on the data request frames sent by the terminal 100, and then calculate the outbound S2C-d channel quality. Based on the S2C-d channel quality, the BeiDou network device 200 can determine the outbound MCS. In this way, without additional signaling overhead, the BeiDou network device 200 can select the outbound MCS, improving channel utilization.

[0331] Figure 13 The illustration shows a flowchart of an outbound data transmission method in a BeiDou communication system according to an embodiment of this application.

[0332] like Figure 13 As shown, the method includes:

[0333] S1301, Terminal 100 sends a data request frame to Beidou network device 200.

[0334] Specifically, in BeiDou network equipment 200, data request frames can include mailbox information query frames and email download frames. The frame formats for mailbox information query frames and email download frames can be found in [reference needed]. Figure 14 .

[0335] like Figure 14 As shown, an incoming physical frame may include a synchronization header, a data segment, and a check bit. The synchronization header distinguishes the frame type of the incoming physical frame, and its duration can be 40ms. Frame types may include location reporting frames, emergency rescue frames, and message communication frames. When the incoming physical frame is a message communication frame, the value of the synchronization header indicates that it is a message communication frame. The check bit is used to verify the integrity of the data in the data segment. In the BeiDou communication system, Cyclic Redundancy Check (CRC) can be used to verify the data segment, and this check bit may include a CRC checksum.

[0336] This data segment may include user frames, which may include frame header information and user information. The frame header information may include a version number field, a subtype indicator field, a user ID field, and a reserved (RSV) field. The version number field indicates the protocol format version of the user frame. The subtype indicator field indicates the subtype of the user frame, which may include general data frames, ACK frames, and acknowledgment frames, etc. The user ID field indicates the device identifier of terminal 100.

[0337] User information may include application-layer messages. These messages may include a header and data. The header may include a service type field, an encryption indicator field, and a compression indicator field. The service type field indicates the service type of the application-layer message. Service types may include mailbox overview query service, mail download service, and communication message service.

[0338] When the service type of the application layer message is mailbox overview query service, the message data can carry the query information of terminal 100. The query information includes the time of the query by terminal 100, the number of messages sent to terminal 100 by the specified user, etc.

[0339] When the service type of the application layer message is a letter download service, the message data can carry an identifier of the letter message that the terminal 100 requests the Beidou network device 200 to send.

[0340] S1302, Beidou Network Equipment 200 measures the channel quality of the inbound channel when a data request frame is received.

[0341] S1303 and Beidou Network Equipment 200 determine the channel quality of the S2C-d channel based on the channel quality of the inbound channel.

[0342] In the BeiDou communication system, the transmission paths of the inbound channel and the outbound S2C-d channel are not significantly different in space. However, because the frequencies of the inbound channel and the outbound S2C-d channel are different, there are certain differences in the channel quality between the inbound channel and the outbound S2C-d channel.

[0343] After measuring the channel quality of the inbound and outbound channels, the BeiDou network equipment 200 can calculate the channel quality of the outbound S2C-d channel based on the channel quality of the inbound channel. Channel quality can be measured, but is not limited to, using SNR (Surface Rate of Return).

[0344] Among them, the SNR of the outgoing S2C-d channel can be determined by the following formula (2):

[0345] SNR Tx =SNR Rx +Δ formula (2)

[0346] In the above formula (2), SNR Tx SNR of the outbound S2C-d channel Rx Let denoted as SNR of the inbound channel, and Δ as the channel quality difference between the outbound S2C-d channel and the inbound channel. The channel quality difference is time-varying; in practice, the BeiDou network device 200 can periodically update this channel quality difference.

[0347] S1304, Beidou Network Equipment 200 Channel Quality Determination Outbound MCS Based on S2C-d Channel.

[0348] Specifically, the BeiDou network device 200 can determine the outgoing MCS based on the SNR of the S2C-d channel from the SNR-MCS mapping table. This SNR-MCS mapping table can be obtained through physical layer simulation in the BeiDou communication system. For example, the SNR-MCS mapping table can refer to the above... Figure 9 Table 1 in the illustrated embodiment will not be repeated here.

[0349] S1305, Beidou Network Equipment 200 responds to the data request frame and generates the first application layer message.

[0350] Specifically, after receiving a data request frame, the Beidou network device 200 can parse the application layer message from the data request frame and distinguish the service type of the data request frame from the service type indication field of the application layer service message.

[0351] If the service type of the data request frame is mailbox overview query service, the terminal 100 generates the first application layer message based on the query information.

[0352] If the service type of the data request frame is a mail download service, the terminal 100 parses the message identifier sent by the BeiDou network device 200, which is requested by the terminal 100, carried in the message data of the data request frame. Based on the message identifier sent by the BeiDou network device 200, the BeiDou network device 200 can determine the first message from the mailbox of the terminal 100 and generate the first application layer message based on the first message.

[0353] S1306, Beidou Network Equipment 200 splits the first application layer message into one or more user frames, and the one or more user frames include the second user frame.

[0354] The second user frame can be any one of the user frames in one or more of the first application layer messages.

[0355] Specifically, regarding the process by which BeiDou network equipment 200 splits the first application layer message into multiple user frames, please refer to the aforementioned... Figure 7 The protocol encapsulation process for application layer messages in the illustrated embodiment will not be described in detail here.

[0356] S1307 and Beidou network equipment 200 place the second user frame into the first physical frame and encode and modulate the first physical frame based on the outgoing MCS.

[0357] S1308, Beidou network equipment 200 sends the first outgoing data (including pilot information on the S2C-p channel and the first physical frame after coding and modulation on the S2C-d channel).

[0358] S1309, Terminal 100 blindly decodes the second user frame of Terminal 100 from the first outgoing data.

[0359] Because the BeiDou network equipment 200 transmits outbound data at a low rate (e.g., 2kbps, 4kbps, etc.), the terminal 100 can perform multiple (e.g., 1000) decoding operations within the transmission time of one physical frame (e.g., 125ms). Therefore, the terminal 100 can adopt a blind decoding strategy to decode the second user frame from the first outbound data.

[0360] In this process, terminal 100 can iterate through different MCSs supported by the BeiDou network device 200 to demodulate and decode the first outgoing data. If the checksum (e.g., CRC checksum) calculated by terminal 100 based on the data segment in the decoded physical frame is the same as the value of the check bit field in the decoded physical frame, then terminal 100 determines that the decoding is successful, and the MCS used by terminal 100 for successful decoding is the outgoing MCS used by BeiDou network device 200. If the checksum calculated by terminal 100 for the data segment in the decoded physical frame is different from the value of the check bit field in the decoded physical frame, then terminal 100 determines that the decoding has failed, and terminal 100 uses other MCSs to demodulate and decode the first outgoing data again, until the first outgoing data is successfully decoded.

[0361] The outbound data transmission method in the BeiDou communication system provided in this application embodiment enables the BeiDou network device 200 to measure the channel quality of the inbound channel based on the data request frame sent by the terminal 100, and then calculate the channel quality of the outbound S2C-d channel. Based on the channel quality of the S2C-d channel, the BeiDou network device 200 can determine the outbound MCS. In this way, without additional signaling overhead, the BeiDou network device 200 can select the outbound MCS, improving channel utilization.

[0362] The foregoing details the method provided in this application. In order to facilitate better implementation of the above-described solutions in the embodiments of this application, the embodiments of this application also provide corresponding devices or equipment.

[0363] This application embodiment can divide the terminal 100 into functional modules according to the above method example. For example, each function can be divided into its own functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0364] The following will combine Figures 15 to 18 The communication device of the embodiments of this application is described in detail.

[0365] In the case of using integrated units, see Figure 15 , Figure 15 This is a schematic diagram of the structure of the communication device 1500 provided in an embodiment of this application. The communication device 1500 can be the terminal 100 in the above embodiments. Optionally, the communication device 1500 can be a chip / chip system, such as a Beidou communication chip. Figure 15 As shown, the communication device 1500 may include a transceiver unit 1510 and a processing unit 1520.

[0366] In one design, the transceiver unit 1510 can be used to send a first user frame to a BeiDou network device. The first user frame carries a first modulation and coding scheme (MCS) indicator field, which suggests that the BeiDou network device use the first MCS for encoding and modulation when sending user frames from the first terminal.

[0367] The transceiver unit 1510 is also used to receive the first outgoing data sent by the Beidou network equipment. The first outgoing data includes a first physical frame that has been encoded and modulated on the data channel and pilot information on the pilot channel.

[0368] The processing unit 1520 can be used to parse the second user frame sent from the first outgoing data to the first terminal by the Beidou network device based on the first MCS.

[0369] The first user frame mentioned above can be a data request frame; for details, please refer to the preceding text. Figure 9 The illustrated embodiment. Optionally, the first user frame can also be an ACK frame; for details, please refer to the foregoing. Figure 11 The embodiments shown are not described in detail here.

[0370] Optionally, the transceiver unit 1510 can also be used to perform the above-mentioned tasks. Figure 9 , Figure 11 or Figure 13 The method embodiment shown illustrates the functional steps related to sending and receiving performed by terminal 100.

[0371] Optionally, the processing unit 1520 can also be used to perform the above. Figure 9 , Figure 11 or Figure 13 The method embodiment shown illustrates the functional steps performed by terminal 100, including decoding, channel quality measurement, or determining the MCS based on channel quality.

[0372] It should be understood that the communication device 1500 in this design can perform the method steps executed by the terminal 100 in the aforementioned embodiment, and for the sake of brevity, it will not be described again here.

[0373] In the case of using integrated units, see Figure 16 , Figure 16 This is a schematic diagram of the communication device 1600 provided in an embodiment of this application. The communication device 1600 can be the BeiDou network device 200 in the above embodiments. Optionally, the communication device 1600 can be a specific network element in the BeiDou network device 200, such as one or a combination of multiple network elements from the BeiDou ground transceiver station 22, the BeiDou central station 23, and the BeiDou short message fusion communication platform 24. Figure 16 As shown, the communication device 1600 may include a transceiver unit 1610 and a processing unit 1620.

[0374] In one design, the transceiver unit 1610 can be used to transmit a first user frame from a first terminal, wherein the first user frame carries a first MCS indication field, and the first MCS indication field is used to suggest that the BeiDou network device use the first MCS for encoding and modulation when transmitting the user frame from the first terminal.

[0375] The transceiver unit 1610 is further configured to continue receiving SLC PDUs from the first SLC SDU sent by the terminal 100 when the acknowledgment mode indicated by the combination of the first frame total number field and the first frame sequence number field is a parallel acknowledgment mode. In the parallel acknowledgment mode, the first frame total number field indicates the total number N of SLC PDUs in the first SLC SDU, and the first frame sequence number field indicates the frame sequence number of the first SLC PDU within the first SLC SDU.

[0376] The processing unit 1620 can be used to put the second user frame to be sent to the first terminal into the first physical frame, and use the first MCS to encode and modulate the first physical frame.

[0377] The transceiver unit 1610 is also used to transmit first outgoing data, which includes the first physical frame encoded and modulated on the data channel and pilot information on the pilot channel.

[0378] The first user frame mentioned above can be a data request frame; for details, please refer to the preceding text. Figure 9 The illustrated embodiment. Optionally, the first user frame can also be an ACK frame; for details, please refer to the foregoing. Figure 11 The embodiments shown are not described in detail here.

[0379] Optionally, the transceiver unit 1610 can also be used to perform the above-mentioned tasks. Figure 9 , Figure 11 or Figure 13 The method embodiment shown illustrates the functional steps related to sending and receiving performed by the BeiDou network device 200.

[0380] Optionally, the processing unit 1620 can also be used to perform the above. Figure 9 , Figure 11 or Figure 13 The illustrated method embodiment shows the functional steps performed by the BeiDou network device 200 related to modulation and coding, channel quality measurement, or determination of the outgoing MCS.

[0381] It should be understood that the communication device 1600 in this design can perform the method steps executed by the Beidou network device 200 in the aforementioned embodiment, and for the sake of brevity, it will not be described again here.

[0382] The terminal 100 and Beidou network device 200 of this application embodiment have been described above. It should be understood that any device possessing the above-described... Figure 15 Any product of the aforementioned terminal 100 functions, as long as it possesses the above-mentioned features. Figure 16 Any form of product that incorporates the functions of the Beidou network device 200 falls within the protection scope of the embodiments of this application.

[0383] As a possible product form, the terminal 100 described in this application embodiment can be implemented using a general bus architecture.

[0384] See Figure 17 , Figure 17 This is a schematic diagram of the structure of the communication device 1700 provided in an embodiment of this application. The communication device 1700 may be a terminal 100, or a device therein. Figure 17 As shown, the communication device 1700 includes a processor 1701 and a transceiver 1702 internally connected and communicating with the processor. The processor 1701 can be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU) for satellite communication. The baseband processor can process satellite communication protocols and data, while the CPU can control the communication device (e.g., baseband chip, terminal, terminal chip), execute computer programs, and process data from these programs. The transceiver 1702, also known as a transceiver unit, transceiver, or transceiver circuit, is used to implement transceiver functions. The transceiver 1702 may include a receiver and a transmitter. The receiver, also known as a receiver circuit, is used to implement a receiving function; the transmitter, also known as a transmitter circuit, is used to implement a transmitting function. Optionally, the communication device 1700 may also include an antenna 1703 and / or a radio frequency unit (not shown in the figure). The antenna 1703 and / or radio frequency unit may be located inside the communication device 1700 or separate from the communication device 1700, that is, the antenna 1703 and / or radio frequency unit may be deployed remotely or in a distributed manner.

[0385] Optionally, the communication device 1700 may include one or more memories 1704, which may store instructions, which may be computer programs, that can be executed on the communication device 1700 to cause the communication device 1700 to perform the methods described in the above method embodiments. Optionally, the memory 1704 may also store data. The communication device 1700 and the memory 1704 may be provided separately or integrated together.

[0386] The processor 1701, transceiver 1702, and memory 1704 can be connected via a communication bus.

[0387] In one design, the communication device 1700 can be used to perform the functions of the terminal 100 in the aforementioned embodiments; the processor 1701 can be used to perform the above-mentioned functions. Figure 9 , Figure 11 or Figure 13 In the illustrated embodiment, terminal 100 performs functional steps related to decoding, channel quality measurement, or determining the MCS based on channel quality, and / or other processes used in the techniques described herein; transceiver 1702 can be used to perform the above. Figure 9 , Figure 11 or Figure 13 The terminal 100 in the illustrated embodiment performs functional steps related to sending and receiving and / or other processes used in the techniques described herein.

[0388] In any of the above designs, the processor 1701 may include a transceiver for implementing receive and transmit functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or it may be used for transmitting or relaying signals.

[0389] In any of the above designs, the processor 1701 may store instructions, which may be computer programs. These computer programs, running on the processor 1701, cause the communication device 1700 to execute the method steps performed by the terminal 100 in the above method embodiments. The computer program may be embedded in the processor 1701; in this case, the processor 1701 may be implemented in hardware.

[0390] In one implementation, the communication device 1700 may include circuitry capable of performing the functions of transmitting, receiving, or communicating as described in the foregoing method embodiments. The processor and transceiver described in this application can be implemented on integrated circuits (ICs), analog ICs, radio frequency integrated circuits (RFICs), mixed-signal ICs, application-specific integrated circuits (ASICs), printed circuit boards (PCBs), electronic devices, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal-oxide-semiconductor (CMOS), n-metal-oxide-semiconductor (NMOS), p-type metal-oxide-semiconductor (PMOS), bipolar junction transistors (BJTs), bipolar CMOS (BiCMOS), silicon-germanium (SiGe), gallium arsenide (GaAs), etc.

[0391] The scope of the communication device described in this application is not limited thereto, and the structure of the communication device may vary. Figure 17 The communication device 1700 may be a standalone device or part of a larger device. For example, the communication device 1700 may be:

[0392] (1) Independent integrated circuit IC, or chip, or chip system or subsystem;

[0393] (2) A collection of one or more ICs, optionally including storage components for storing data and computer programs;

[0394] (3) ASIC, such as modem;

[0395] (4) Modules that can be embedded in other devices;

[0396] (5) Receivers, terminals, smart terminals, cellular phones, wireless devices, handheld devices, mobile units, vehicle-mounted devices, network devices, cloud devices, artificial intelligence devices, etc.

[0397] (6) Others, etc.

[0398] As a possible product form, any network element in the BeiDou network device 200 described in this application embodiment (e.g., BeiDou ground transceiver station 22, BeiDou central station 23, BeiDou short message fusion communication platform 24) can be implemented by a general bus architecture.

[0399] See Figure 18 , Figure 18 This is a schematic diagram of the structure of the communication device 1800 provided in an embodiment of this application. The communication device 1800 may be a BeiDou network device 200, or a device therein. Figure 18 As shown, the communication device 1800 includes a processor 1801 and a transceiver 1802 internally connected and communicating with the processor. The processor 1801 can be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU) for satellite communication. The baseband processor can process satellite communication protocols and data, while the CPU can control the communication device (e.g., a baseband chip), execute computer programs, and process data from those programs. The transceiver 1802, also known as a transceiver unit, transceiver, or transceiver circuit, is used to implement transceiver functions. The transceiver 1802 may include a receiver and a transmitter. The receiver, also known as a receiver circuit, is used to implement a receiving function; the transmitter, also known as a transmitter or transmitting circuit, is used to implement a transmitting function. Optionally, the communication device 1800 may also include an antenna 1803 and / or a radio frequency unit (not shown in the figure). The antenna 1803 and / or radio frequency unit may be located inside the communication device 1800 or separate from the communication device 1800, that is, the antenna 1803 and / or radio frequency unit may be deployed remotely or in a distributed manner.

[0400] Optionally, the communication device 1800 may include one or more memories 1804, which may store instructions, which may be computer programs, that can be executed on the communication device 1800 to cause the communication device 1800 to perform the methods described in the above method embodiments. Optionally, the memory 1804 may also store data. The communication device 1800 and the memory 1804 may be provided separately or integrated together.

[0401] The processor 1801, transceiver 1802, and memory 1804 can be connected via a communication bus.

[0402] In one design, the communication device 1800 can be used to perform the functions of the Beidou network device 200 in the aforementioned embodiments: the processor 1801 can be used to perform the above-mentioned functions. Figure 9 , Figure 11 or Figure 13The BeiDou network device 200 in the illustrated embodiment performs functional steps related to modulation and coding, channel quality measurement, or determination of the outgoing MCS, and / or other processes used in the techniques described herein; the transceiver 1802 can be used to perform the above-mentioned functions. Figure 9 , Figure 11 or Figure 13 The BeiDou network device 200 in the illustrated embodiment performs functional steps related to sending and receiving and / or other processes used in the technology described herein.

[0403] In any of the above designs, the processor 1801 may include a transceiver for implementing receive and transmit functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or it may be used for transmitting or relaying signals.

[0404] In any of the above designs, the processor 1801 may store instructions, which may be computer programs. These computer programs, running on the processor 1801, cause the communication device 1800 to execute the method steps executed by the terminal 100 in the above method embodiments. The computer program may be embedded in the processor 1801; in this case, the processor 1801 may be implemented in hardware.

[0405] This application also provides a computer-readable storage medium storing computer program code. When the processor executes the computer program code, the electronic device performs the method in any of the foregoing embodiments.

[0406] This application also provides a computer program product that, when run on a computer, causes the computer to perform the methods in any of the foregoing embodiments.

[0407] This application also provides a communication device, which can exist in the form of a chip. 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 can execute the method in any of the foregoing embodiments.

[0408] This application also provides a BeiDou communication system, including a terminal 100 and a BeiDou network device 200, which can perform the methods in any of the foregoing embodiments.

[0409] This application fully describes the short message communication function in the BeiDou communication system. It is understood that other satellite systems may also support short message communication functions. Therefore, it is not limited to the BeiDou communication system. If other satellite systems also support short message communication functions, the method described in this application is also applicable to the communication of other satellite systems.

[0410] The steps of the methods or algorithms described in this application can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a core network interface device. Of course, the processor and storage medium can also exist as discrete components in the core network interface device.

[0411] Those skilled in the art will recognize that, in one or more of the examples above, the functions described in this application can be implemented using hardware, software, firmware, or any combination thereof. When implemented in software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer-readable storage media and communication media, wherein communication media include any medium that facilitates the transmission of a computer program from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer.

[0412] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for outbound data transmission in a BeiDou communication system, characterized in that, include: A first terminal sends a first user frame to a BeiDou network device via a BeiDou short message satellite. The first user frame carries a first modulation and coding scheme (MCS) indicator field, which suggests that the BeiDou network device use the first MCS for encoding and modulation when sending the user frame from the first terminal. The first user frame is either a data request frame or an acknowledgment (ACK) frame. The data request frame requests the BeiDou network device to send service data to the first terminal, and the ACK frame indicates the first terminal's reception status of the user frame sent by the BeiDou network device. The first terminal receives the first outgoing data sent by the BeiDou network device via the BeiDou short message satellite. The first outgoing data includes a first physical frame that has been encoded and modulated on the data channel and pilot information on the pilot channel. The first terminal parses the second user frame sent by the BeiDou network device to the first terminal via the BeiDou short message satellite from the first outgoing data based on the first MCS; wherein, the first physical frame includes user frames sent by the BeiDou network device to multiple terminals via the BeiDou short message satellite, the user frames of the multiple terminals include the second user frame of the first terminal, and the order of the MCS used by the BeiDou network device to encode and modulate the first physical frame is less than or equal to the order of the first MCS.

2. The method according to claim 1, characterized in that, If the first user frame is a data request frame, the frame header information of the data request frame includes the first MCS indicator field, and the value of the first MCS indicator field is used to indicate the order of the first MCS. Before the first terminal sends the first user frame to the BeiDou network equipment via the BeiDou short message satellite, the method further includes: The first terminal receives pilot information sent by the BeiDou network device on the pilot channel via the BeiDou short message satellite, and measures the channel quality on the pilot channel; The first terminal determines the channel quality of the data channel based on the channel quality on the pilot channel; The first terminal determines the first MCS based on the channel quality of the data channel and the mapping relationship between channel quality and MCS.

3. The method according to claim 2, characterized in that, The data request frame includes a service type field, which indicates the service type of the data request frame. The value of the service type field is a first value or a second value. The first value indicates that the service type of the data request frame is a mailbox overview query service, and the second value indicates that the service type of the data request frame is a letter message download service.

4. The method according to claim 2, characterized in that, The channel quality of the pilot channel includes the signal-to-noise ratio (SNR) of the pilot channel, and the channel quality of the data channel includes the SNR of the data channel. The first terminal determines the SNR of the data channel using the following formula: in, The SNR of the data channel, δ is the SNR of the pilot channel, and δ is the channel quality difference between the data channel and the pilot channel.

5. The method according to claim 1, characterized in that, If the first user frame is an acknowledgment identifier (ACK) frame, before the first terminal sends the first user frame to the BeiDou network equipment via the BeiDou short message satellite, the method further includes: The first terminal receives the second outgoing data sent by the BeiDou network device via the BeiDou short message satellite. The second outgoing data includes a second physical frame that has been encoded and modulated on the data channel and pilot information on the pilot channel. The first terminal uses the third MCS to decode the third user frame from the second physical frame and measures the channel quality on the data channel; The first terminal determines the first MCS based on the channel quality on the data channel, and the first user frame is used to indicate that the first terminal has received the third user frame.

6. The method according to claim 5, characterized in that, The header information of the first user frame includes the first MCS indicator field. The value of the first MCS indicator field is used to indicate the order of the first MCS, or the value of the first MCS indicator field is used to indicate the order of the first MCS compared with the third MCS.

7. The method according to claim 5, characterized in that, The ACK field of the ACK frame includes the first MCS indication field; wherein, The value of the first MCS indicator field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the first MCS order; or, The value of the first MCS indication field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS compared with the third MCS.

8. The method according to any one of claims 2-4, characterized in that, After the first terminal parses the second user frame sent by the BeiDou network device to the first terminal from the first outgoing data based on the first MCS, the method further includes: The first terminal sends a first ACK via the BeiDou short message satellite. The first ACK is used to indicate that the first terminal has received the second user frame sent by the BeiDou network device. The first ACK includes a second MCS indication field, which is used to suggest that the BeiDou network device use a fourth MCS for encoding and modulation when sending the user frame of the first terminal. The first terminal receives the third outgoing data sent by the BeiDou network device through the BeiDou short message satellite, wherein the third outgoing data includes a third physical frame encoded and modulated on the data channel and pilot information on the pilot channel; The first terminal parses the fourth user frame sent by the BeiDou network device to the first terminal from the third outbound data based on the fourth MCS.

9. A method for outbound data transmission in a BeiDou communication system, characterized in that, include: BeiDou network equipment receives user frames sent by multiple terminals via BeiDou short message satellites. These user frames include a first user frame sent by a first terminal. Each user frame carries an MCS indication field, which suggests that the BeiDou network equipment use the indicated MCS for encoding and modulation when sending user frames to the terminals. The user frames sent by the terminals are either data request frames or acknowledgment (ACK) frames. The data request frame requests the BeiDou network equipment to send service data to the terminal, while the ACK frame indicates the terminal's reception status of the user frames sent by the BeiDou network equipment. The Beidou network device puts the user frames to be sent to the multiple terminals into a first physical frame, and uses the MCS with the smallest order among the MCSs indicated in the user frames sent by the multiple terminals to encode and modulate the first physical frame. The user frames to be sent to the multiple terminals include a second user frame to be sent to the first terminal. The BeiDou network device sends the first outgoing data through the BeiDou short message satellite. The first outgoing data includes the first physical frame that has been encoded and modulated on the data channel and the pilot information on the pilot channel.

10. The method according to claim 9, characterized in that, If the first user frame is a data request frame, the frame header information of the data request frame includes a first MCS indicator field, and the value of the first MCS indicator field is used to indicate the order of the first MCS. After the BeiDou network device receives user frames sent by multiple terminals via BeiDou short message satellites, the method further includes: The BeiDou network device responds to the data request frame by generating a first application layer message; The BeiDou network device splits the first application layer message into one or more user frames, and the one or more user frames include the second user frame.

11. The method according to claim 10, characterized in that, The data request frame includes a service type field, which is used to indicate the service type of the data request frame. The value of the service type field is a first value, which indicates that the service type of the data request frame is a mailbox overview query service. In response to the data request frame, the BeiDou network device generates a first application layer message, which specifically includes: In response to the data request frame, the BeiDou network device generates a first application layer message based on the mailbox profile information of the first terminal. The mailbox profile information of the first terminal includes one or more of the following: the number of email messages to be downloaded by the first terminal, the sending time, and the sender identifier.

12. The method according to claim 10, characterized in that, The data request frame includes a service type field, which indicates the service type of the data request frame. The value of the service type field is a second value, which indicates that the service type of the data request frame is a letter message download service. In response to the data request frame, the BeiDou network device generates a first application layer message, which specifically includes: In response to the data request frame, the BeiDou network device retrieves the first email message from the mailbox of the first terminal and generates a first application layer message based on the first email message.

13. The method according to claim 9, characterized in that, If the first user frame is an ACK frame, before the BeiDou network device receives user frames sent by multiple terminals via the BeiDou short message satellite, the method further includes: The Beidou network device puts the third user frame to be sent to the first terminal into the second physical frame, and uses the third MCS to encode and modulate the second physical frame. The BeiDou network device transmits second outgoing data via the BeiDou short message satellite. The second outgoing data includes the second physical frame encoded and modulated by the third MCS on the data channel and pilot information on the pilot channel. The first user frame is used to indicate that the first terminal has received the third user frame.

14. The method according to claim 13, characterized in that, The header information of the first user frame includes a first MCS indicator field. The value of the first MCS indicator field is used to indicate the order of the first MCS, or the value of the first MCS indicator field is used to indicate the order of the first MCS compared with the third MCS.

15. The method according to claim 13, characterized in that, The ACK field of the ACK frame includes a first MCS indication field; wherein, The value of the first MCS indicator field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS; or, The value of the first MCS indication field is used to indicate whether the first terminal has received the second user frame sent by the BeiDou network device and the order of the first MCS compared with the third MCS.

16. The method according to any one of claims 10-12, characterized in that, After the BeiDou network equipment sends the first outbound data via BeiDou short message satellite, the method further includes: The BeiDou network device receives the first ACK sent by the first terminal through the BeiDou short message satellite. The first ACK is used to indicate that the first terminal has received the second user frame sent by the BeiDou network device. The first ACK includes a second MCS indication field, which is used to suggest that the BeiDou network device use a fourth MCS for encoding and modulation when sending the user frame of the first terminal. The Beidou network device puts the fourth user frame to be sent to the first terminal into the third physical frame, and uses the fourth MCS to encode and modulate the third physical frame. The BeiDou network equipment transmits third outgoing data via the BeiDou short message satellite. The third outgoing data includes the third physical frame encoded and modulated on the data channel and pilot information on the pilot channel.

17. The method according to claim 9, characterized in that, The user frames sent by the multiple terminals also include a fifth user frame sent by the second terminal. The MCS indication field in the fifth user frame is used to suggest that the BeiDou network device use the fifth MCS for encoding and modulation when sending the user frames of the second terminal. The BeiDou network device places the user frames to be sent to the multiple terminals into a first physical frame, and encodes and modulates the first physical frame using the MCS with the smallest order among the MCSs indicated in the user frames sent by the multiple terminals. Specifically, this includes: The BeiDou network device places the second user frame to be sent to the first terminal and the fifth user frame to be sent to the second terminal into the first physical frame, and uses the first MCS to encode and modulate the first physical frame, wherein the order of the first MCS is less than or equal to the order of the fifth MCS.

18. A BeiDou communication system, characterized in that, This includes the first terminal and BeiDou network equipment; among them, The first terminal is configured to execute the method according to any one of claims 1-8; The BeiDou network equipment is used to perform the method according to any one of claims 9-17.

19. A communication device, characterized in that, The device includes one or more processors, one or more memories, and a transceiver; wherein the transceiver, the one or more memories, and the one or more processors are coupled together, the one or more memories being used to store computer program code, the computer program code including computer instructions, which, when executed by the one or more processors, cause the communication device to perform the method as described in any one of claims 1-8.

20. The communication device according to claim 19, characterized in that, The communication device is the first terminal.

21. A communication device, characterized in that, The device includes one or more processors, one or more memories, and a transceiver; wherein the transceiver, the one or more memories, and the one or more processors are coupled together, and the one or more memories are used to store computer program code, the computer program code including computer instructions, which, when executed by the one or more processors, cause the communication device to perform the method as described in any one of claims 9-17.

22. The communication device according to claim 21, characterized in that, The communication device is a BeiDou network device.

23. A computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method as described in any one of claims 1-8.

24. A computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method as described in any one of claims 9-17.

25. A chip system applied to a first terminal, characterized in that, It includes a processing circuit and an interface circuit, wherein the interface circuit is used to receive code instructions and transmit them to the processing circuit, and the processing circuit is used to execute the code instructions to perform the method as described in any one of claims 1-8.

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