A satellite communication data transmission system

Abstract

The application discloses a satellite communication data transmission system, comprising: a transmitting end host computer, a transmitter physical layer baseband module, a digital up-conversion module, a digital down-conversion module, a receiver physical layer baseband module and a receiving end host computer; the transmitting end host computer is used for transmitting a first signal to the transmitter physical layer baseband module through an Ethernet; the transmitter physical layer baseband module is used for processing the first signal and sending a processed second signal to the digital up-conversion module; the digital up-conversion module is used for frequency conversion of the second signal and transmitting a third signal after frequency conversion through an antenna; the digital down-conversion module is used for frequency conversion of a fourth signal received by the antenna; and the receiver physical layer baseband module is used for processing a fifth signal after frequency conversion and transmitting a sixth signal after processing to the receiving end host computer through an Ethernet interface. The application can efficiently transmit IP packets with different lengths.

Description

Technical Field

[0001] This invention relates to the field of communications. More specifically, it relates to a satellite communication data transmission system. Background Technology

[0002] Currently, high-throughput, high-bandwidth, and IP-based satellite internet has become the mainstream of satellite communication. However, most systems using QPSK or OQPSK modes generally suffer from low spectral efficiency and limited flexibility. To address these needs and shortcomings of existing systems, this invention proposes a satellite communication data transmission system that extends the digital modulation order to 8PSK, thus improving the problem of low transmission spectral efficiency. Furthermore, the transmission mode proposed in this invention adds sufficiently efficient fields representing encoding and modulation information to the data encapsulation of each transmission, greatly benefiting burst mode data transmission and facilitating the efficient transmission of IP packets of varying lengths. Summary of the Invention

[0003] One object of the present invention is to provide a satellite communication data transmission system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A satellite communication data transmission system includes: a transmitter host computer, a transmitter physical layer baseband module, a digital up-conversion module, a digital down-conversion module, a receiver physical layer baseband module, and a receiver host computer;

[0006] The host computer at the transmitter is used to transmit the first signal to the physical layer baseband module of the transmitter via Ethernet.

[0007] The transmitter physical layer baseband module is used to process the first signal and send the processed second signal to the digital upconversion module;

[0008] The digital up-conversion module is used to convert the second signal into a frequency and transmit the converted third signal through an antenna.

[0009] The digital downconversion module is used to convert the fourth signal received by the antenna.

[0010] The receiver physical layer baseband module is used to process the frequency-converted fifth signal and transmit the processed sixth signal to the host computer at the receiving end via an Ethernet interface.

[0011] Preferably, the transmitter physical layer baseband module includes

[0012] An error correction coding unit is used to process the first signal received by the transmitter physical layer baseband module to obtain a first intermediate signal;

[0013] A digital modulation unit is used to process the first intermediate signal to obtain a second signal;

[0014] The first signal sent by the host computer at the transmitting end is output to the error correction coding unit. The error correction coding unit sequentially scrambles, performs CRC encoding and LDPC encoding on the first signal to obtain the first intermediate signal. The digital modulation unit sequentially performs bit interleaving and symbol mapping processing on the first intermediate signal to output the second signal.

[0015] Preferably, the transmitter physical layer baseband module is configured to have a random access burst working mode and a service data burst working mode;

[0016] The transmitter physical layer baseband module, operating in random access burst mode, is used to process and transmit requests for establishing connections to the gateway in the transmitter's transmitted signals.

[0017] The transmitter physical layer baseband module, operating in business data burst mode, is used to process and transmit data signals other than connection requests in the host computer's transmitted signals.

[0018] Preferably, the transmitter physical layer baseband module processes the first signal by selecting an operating mode based on the first signal.

[0019] Preferably, the data structure of the business data burst working mode includes a preamble, a frame header, block codewords, and a postamble;

[0020] The data structure of the random access burst mode includes a preamble and block codewords.

[0021] Preferably, the scrambling includes bit-level scrambling of the first signal sent by the host computer at the transmitting end to obtain a scrambled output sequence;

[0022] The CRC encoding includes performing CRC check calculation on the scrambled output sequence and appending the obtained CRC check sequence to the scrambled output sequence to obtain a CRC encoded output sequence.

[0023] The LDPC encoding includes performing a check calculation on the CRC encoded output sequence according to the LDPC encoding algorithm, and appending the obtained LDPC check sequence to the CRC encoded output sequence to obtain an LDPC encoded output sequence as the first intermediate signal.

[0024] The bit interleaving includes bit interleaving each block codeword of the first intermediate signal using an in-row-out matrix interleaving, wherein the number of columns of the interleaving matrix is ​​the order of the symbol mapping constellation diagram.

[0025] Preferably, when the number of LDPC codewords included in the first signal processed by the error correction coding unit is greater than 1, each LDPC codeword is subjected to bit interleaving operation independently, and the CRC encoding and LDPC encoding between the codewords can be implemented in parallel. The output result is processed by the MUX module (convergence module) to form a single-ended output to the digital modulation unit.

[0026] Preferably, the transmitter physical layer baseband module further includes a PLSC, used to determine the operating mode, signal modulation method, LDPC code length and code rate of the baseband module based on the first signal.

[0027] Preferably, in the service data burst mode, the physical layer baseband module of the transmitter obtains a symbol vector by encoding bits using first-order Reed-Muller coding, content repetition, bit scrambling, and π / 2-BPSK modulation, and embeds it into the frame header field.

[0028] In the random access burst mode, the baseband module maps bits into 100-bit random vectors and then performs π / 2-BPSK modulation, and the modulation result is filled into the preamble field.

[0029] Preferably, the symbol mapping includes BPSK, π / 2-BPSK, QPSK, and 8PSK, whose constellation points lie on a circle of constant radius; wherein

[0030] 8PSK is used in the burst mode of service data operation; BPSK is used in the burst mode of random access operation; QPSK is used in the burst mode of service data operation and / or the burst mode of random access operation; π / 2-BPSK is used in the burst mode of service data operation and / or the burst mode of random access operation.

[0031] The beneficial effects of this invention are as follows:

[0032] This invention supports 8PSK digital modulation, which offers higher spectral transmission efficiency compared to QPSK or OQPSK in most existing systems. The transmission mode proposed in this invention adds sufficiently efficient fields representing encoding and modulation information to the data encapsulation of each transmission, greatly benefiting burst mode data transmission and facilitating the efficient transmission of IP packets of varying lengths. Attached Figure Description

[0033] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] Figure 1 A block diagram of the communication data transmission system according to the present invention is shown.

[0035] Figure 2This diagram illustrates a flowchart of the transmitter physical layer baseband module processing information according to the present invention.

[0036] Figure 3 A schematic diagram of the DATA-type burst structure described in this invention is shown.

[0037] Figure 4 A schematic diagram of the RACH-type burst structure described in this invention is shown.

[0038] Figure 5 A schematic diagram of the burst pilot insertion method described in this invention is shown.

[0039] Figure 6 The diagram shows the error correction coding structure of the present invention.

[0040] Figure 7 A schematic diagram of the block codeword composition structure described in this invention is shown.

[0041] Figure 8 A schematic diagram of the scrambler structure and scrambling method described in this invention is shown.

[0042] Figure 9 A schematic diagram of the PLSC parameter composition structure described in this invention is shown.

[0043] Figure 10 This diagram illustrates the PLSC b1 to b5 encoding process of the DATA type Burst described in this invention.

[0044] Figure 11 This diagram illustrates the pre-modulation interleaving of the QPSK modulation described in this invention.

[0045] Figure 12 This diagram illustrates the pre-modulation interleaving of the 8PSK modulation described in this invention.

[0046] Figure 13 A schematic diagram of a specific embodiment of the present invention is shown. Detailed Implementation

[0047] To more clearly illustrate the present invention, the following description is in conjunction with preferred embodiments and accompanying drawings. Figure 1-13 The present invention will be further described below. Similar components in the accompanying drawings are indicated by the same reference numerals. Those skilled in the art should understand that the following detailed description is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0048] like Figure 1 As shown, a satellite communication data transmission system includes: a transmitter host computer, a transmitter physical layer baseband module, a digital up-conversion module, a digital down-conversion module, a receiver physical layer baseband module, and a receiver host computer;

[0049] The host computer at the transmitter is used to transmit the first signal to the physical layer baseband module of the transmitter via Ethernet.

[0050] The transmitter physical layer baseband module is used to process the first signal and send the processed second signal to the digital upconversion module;

[0051] The digital upconversion module is used to convert the second signal into a frequency and transmit the converted third signal through an antenna.

[0052] The digital downconversion module is used to convert the fourth signal received by the antenna.

[0053] The receiver physical layer baseband module is used to process the frequency-converted fifth signal and transmit the processed sixth signal to the host computer at the receiving end via an Ethernet interface.

[0054] Preferably, the transmitter's host computer is connected to the transmitter's physical layer baseband module via Ethernet, the transmitter's physical layer baseband module is connected to the digital upconversion module, and the upconversion module is connected to the antenna;

[0055] The host computer at the receiving end is connected to the physical layer baseband module of the receiver via Ethernet. The physical layer baseband module of the receiver is connected to the digital down-conversion module, and the down-conversion module is connected to the antenna.

[0056] The host computer at the transmitter transmits the signal to the physical layer baseband module of the transmitter via Ethernet. The physical layer baseband module of the transmitter processes the signal and transmits it to the digital upconversion module. After being frequency-converted by the digital upconversion module, the signal is transmitted by the antenna.

[0057] The signal received by the receiving antenna is converted by the downconversion module and then sent to the receiver's physical layer baseband module for processing. The receiver's physical layer baseband module then transmits the processing result to the host computer at the receiving end via the Ethernet interface.

[0058] Preferably, the transmitter physical layer baseband module includes

[0059] An error correction coding unit is used to process the first signal received by the transmitter physical layer baseband module to obtain a first intermediate signal;

[0060] A digital modulation unit is used to process the first intermediate signal to obtain a second signal;

[0061] The first signal sent by the host computer at the transmitting end is output to the error correction coding unit. The error correction coding unit sequentially scrambles, performs CRC encoding and LDPC encoding on the first signal to obtain the first intermediate signal. The digital modulation unit sequentially performs bit interleaving and symbol mapping processing on the first intermediate signal to output the second signal.

[0062] Preferably, the transmitter physical layer baseband module is configured to have a random access burst working mode and a service data burst working mode;

[0063] The transmitter physical layer baseband module, operating in random access burst mode, is used to process and transmit requests for establishing connections to the gateway in the transmitter's transmitted signals.

[0064] The transmitter physical layer baseband module, operating in business data burst mode, is used to process and transmit data signals other than connection requests in the host computer's transmitted signals.

[0065] Preferably, the transmitter physical layer baseband module processes the first signal by selecting an operating mode based on the first signal.

[0066] Preferably, the data structure of the business data burst working mode includes a preamble, a frame header, block codewords, and a postamble;

[0067] The data structure of the random access burst mode includes a preamble and block codewords.

[0068] Preferably, the scrambling includes bit-level scrambling of the first signal sent by the host computer at the transmitting end to obtain a scrambled output sequence;

[0069] The CRC encoding includes performing CRC check calculation on the scrambled output sequence and appending the obtained CRC check sequence to the scrambled output sequence to obtain a CRC encoded output sequence.

[0070] The LDPC encoding includes performing a check calculation on the CRC encoded output sequence according to the LDPC encoding algorithm, and appending the obtained LDPC check sequence to the CRC encoded output sequence to obtain an LDPC encoded output sequence as the first intermediate signal.

[0071] The bit interleaving includes bit interleaving each block codeword of the first intermediate signal using an in-row-out matrix interleaving, wherein the number of columns of the interleaving matrix is ​​the order of the symbol mapping constellation diagram.

[0072] The symbol mapping includes performing symbol mapping on the signal after bit interleaving each block codeword of the first intermediate signal using one of BPSK, QPSK, or 8PSK.

[0073] Preferably, when the number of LDPC codewords included in the first signal processed by the error correction coding unit is greater than 1, each LDPC codeword is subjected to bit interleaving operation independently, and the CRC encoding and LDPC encoding between the codewords can be implemented in parallel. The output result is processed by the MUX module (convergence module) to form a single-ended output to the digital modulation unit.

[0074] Preferably, the transmitter physical layer baseband module further includes a PLSC, used to determine the operating mode, signal modulation method, LDPC code length and code rate of the baseband module based on the first signal.

[0075] Preferably, in the service data burst mode, the physical layer baseband module of the transmitter obtains a symbol vector by encoding bits using first-order Reed-Muller coding, content repetition, bit scrambling, and π / 2-BPSK modulation, and embeds it into the frame header field.

[0076] In the random access burst mode, the baseband module maps bits into 100-bit random vectors and then performs π / 2-BPSK modulation, and the modulation result is filled into the preamble field.

[0077] Preferably, the symbol mapping includes BPSK, π / 2-BPSK, QPSK, and 8PSK, whose constellation points lie on a circle of constant radius; wherein

[0078] 8PSK is used in the burst mode of service data operation; BPSK is used in the burst mode of random access operation; QPSK is used in the burst mode of service data operation and / or the burst mode of random access operation; π / 2-BPSK is used in the burst mode of service data operation and / or the burst mode of random access operation.

[0079] Preferably, the receiver physical layer baseband module includes

[0080] An error correction and decoding unit is used to process the fifth signal received by the receiver's physical layer baseband module to obtain a fifth intermediate signal;

[0081] A digital modulation unit is used to process the fifth intermediate signal to obtain a sixth signal.

[0082] Specifically, the transmitter signal transmission operates in burst mode, which includes two types of formats: DATA burst (also known as "service data burst") and RACH burst (also known as "random access burst").

[0083] DATA-type bursts are used for data transmission; RACH-type bursts are used by terminals to initiate access requests to satellites (or gateways). The two types of bursts differ in structure, encoding, and modulation.

[0084] Specifically, in DATA burst and RACH burst modes, the physical layer baseband module of the transmitter processes the received signal through error correction coding, digital modulation, burst formation, and pulse shaping, such as... Figure 2 As shown.

[0085] The DATA type burst and RACH type burst format structures are respectively as follows: Figure 3 and Figure 4 As shown in Table 1, this is further explained.

[0086] like Figure 3 and Figure 4 As shown, the block codeword (symbol level, including pilot) is the result of information bits after error correction coding and digital modulation. Each burst contains 1 to 2 block codewords with the same structure.

[0087] In Table 1, n ldpc The length of each block codeword (bit level) is represented by ∑n. ldpc This parameter represents the total length of the block codewords (bit level), and it determines some of the microstructures of the DATA type burst. In Table 1, parameter L represents the length of this field.

[0088] Table 1 Burst Composition Structure

[0089]

[0090] Pilots in the block codeword (symbol level, including pilots) are used for receiver signal synchronization recovery and are inserted into the block codeword at constant intervals, such as... Figure 5 As shown.

[0091] The number of pilot symbols inserted each time, i.e., the length of a single pilot block, is always 1. However, the pilot block insertion density varies for different types of bursts or different configurations under the same type of burst, as shown in Table 2. Pilot data is the π / 2-BPSK digital modulation result of a random sequence, which is in hexadecimal form as follows:

[0092] 0x8C9D-2D0C-75D8-9F73-C924-2B27-ADC5-FB6E-5A51-F166-2C2D-34A3-6A90-E421-189D-42AD(LEFT-FRST).

[0093] For each burst, the inserted pilot starts with the first bit of the random sequence, rather than continuing from the last bit of the previous burst.

[0094] Table 2 Pilot Insertion Interval

[0095]

[0096] Similar to pilot insertion, the preamble and postamble of DATA-type bursts are also filled with random sequences, and are related to the length of the block codeword (bit level), as shown in Table 1. The random sequences used above are defined as follows:

[0097] 0xDEB1-5BA3-A243-06F9-6C38-2F62-4FF2-3559(LEFT-FIRST).

[0098] The preamble sequence always starts with the first bit of the random sequence, but the suffix sequence follows the preamble sequence in sequence. Regarding error correction coding and symbol mapping, the configurations supported by the two types of bursts are shown in Table 3, which also provides the burst length (symbol level) for different configurations.

[0099] Table 3. Summary Table of Burst Structural Parameters

[0100]

[0101] For any burst, the error correction coding process for its information bits is the same, such as... Figure 6 As shown.

[0102] Since both CRC encoding and LDPC encoding are system block codes, the input and output of error correction coding are both block-based. The block codeword structure of the error correction coding output is as follows: Figure 7 As shown, the bit order of all fields is left-first.

[0103] Specifically, the scrambling used in this invention refers to performing an XOR operation between the binary m-sequence generated by the polynomial 1 + x^14 + x^15 and the block source bits, such as... Figure 8 As shown.

[0104] The polynomial used in this invention is a general representation. Specifically, in this invention, x represents a unit delay, x^14 represents 14 units of delay, and similarly, x^15 represents 15 units of delay. + represents performing a binary XOR operation on the output result of the expression.

[0105] For each burst, the initial value of the register must be set to:

[0106] 100101010000000(right-msb).

[0107] When the number of code blocks is greater than 1, the state of the register corresponding to the subsequent code block will inherit the state of the previous code block, instead of being reinitialized using the sequence 100101010000000.

[0108] Specifically, for each codeword, the CRC check sequence is 16 bits long, that is...

[0109] k ldpc -k crc =16

[0110] Where k_ldpc represents the length of the binary sequence input to the LDPC encoder, and k_crc represents the length of the binary sequence input to the CRC encoder.

[0111] The polynomial used in this invention is a general representation. Specifically, in this invention, x represents a unit delay, x^16 represents 16 units of delay, similarly x^12 represents 12 units of delay, and x^5 represents 5 units of delay.

[0112] The CRC check result is appended to the source bits (after scrambling). CRC encoding is essentially a polynomial modulo operation on the GF(2) field, where the polynomial form of all fields is higher power first (or left-hand side).

[0113] The LDPC encoding used in this invention involves four code lengths (720, 1440, 2880, and 5760 respectively) and four code rates (1 / 2, 2 / 3, 4 / 5, and 9 / 10 respectively). Combining the four code lengths and four code rates yields 16 configurations.

[0114] The modulation-coding parameters described in this invention are also known as PLSC (Physical Layer Signaling Control).

[0115] The PLSC is used to indicate the type of the burst, the signal modulation method, the LDPC code length, and the code rate.

[0116] The PLSC is an indispensable component for the normal transmission of data between the sender and receiver.

[0117] In this invention, PLSC is an 8-bit parameter, in the form of... Figure 9 As shown in Table 4, the specific definitions are as follows.

[0118] Table 4 Specific Definitions of PLSC Parameters

[0119]

[0120] As mentioned above, normal link communication is based on the premise that the receiving end can obtain the correct PLSC. The transmission of bits a1, a2, and a3 in the PLSC is achieved through a specific signaling protocol, which will not be explained further here. Bits b1 to b5 in the PLSC are encoded and embedded into the burst before reaching the receiving end.

[0121] For a DATA type burst, bits b1 to b5 need to undergo first-order (16,5) Reed-Muller coding, content repetition, bit scrambling, π / 2-BPSK modulation, etc. Figure 10 As shown. The resulting 32-symbol vector will be embedded into the frame header field. In principle, first-order (16,5) Reed-Muller coding (the coding algorithm proposed by Reed and Muller) is essentially a vector-matrix multiplication operation, and the generator matrix used is...

[0122]

[0123] G is the Reed-Muller coding generator matrix, which is multiplied by the encoder input vector, and the result is used as the encoder output vector.

[0124] The first-order RM codeword is then repeated bit by bit to expand it to 32 bits: c1c1c2c2…c16c16. Next, the scrambling module uses the following fixed scrambling sequence to scramble bit by bit:

[0125] 00001001011000111110001101110101(LEFT-FIRST).

[0126] For RACH type burst, b1 to b5 are directly mapped to 100-bit random vectors and then π / 2-BPSK modulated. The result is filled into the preamble field. This mapping relationship is shown in Table 5.

[0127] Table 5 PLSC Mapping Lookup Table for RACH Type Burst

[0128] 00000 DEB1-5BA3-A243-06F9-6C38-2F62-4FF2-3559 00001 B504-AA2D-F204-58AC-825E-FA77-ACC1-4570 10000 7A83-EF50-3050-FF1C-20EF-46C6-7BCD-F81C 10001 7308-7BA4-EEFC-DF98-D405-2899-F3E3-917D

[0129] Preferably, the random sequence shown in the table is a 128-bit random vector, and only the first 100 bits are used in actual use.

[0130] Specifically, to address burst errors, an interleaving operation is required before symbol mapping of the bit sequence.

[0131] The interleaving operation involves bit interleaving for each LDPC encoded output codeword; the bit interleaving uses an in-row-out matrix interleaving. The number of columns in the interleaving matrix is ​​equal to the order of the symbol mapping constellation diagram, i.e., 2 columns for QPSK modulation and 3 columns for 8PSK modulation, as shown below. Figure 11 and Figure 12 As shown.

[0132] Specifically, Burst involves four types of symbol mappings: BPSK, π / 2-BPSK, QPSK, and 8PSK. All four symbol mappings belong to phase-shift keying digital modulation, and their constellation points lie on a circle of constant radius. The 8PSK modulation is only used in DATA-type bursts, and its constellation point definition is shown in Table 6.

[0133] Table 6. Definition of 8PSK constellation points

[0134]

[0135] QPSK modulation can occur in both DATA-type Burst and RACH-type Burst, and the constellation point definitions involved are shown in Table 7 and Table 8, respectively.

[0136] Table 7. QPSK Constellation Point Definitions (DATA Type Burst)

[0137]

[0138] Table 8. Definition of QPSK Constellation Points (RACH Type Burst)

[0139]

[0140] π / 2-BPSK modulation is applied to the control fields of DATA-type Burst and RACH-type Burst, as shown in Table 1. Their constellation diagrams are defined in Tables 9 and 10, respectively.

[0141] Table 9π / 2-BPSK Constellation Point Definitions (DATA Type Burst)

[0142] Even position 0 0.7071 0.7071 Even position 1 -0.7071 -0.7071 Odd position 0 -0.7071 0.7071 Odd position 1 0.7071 -0.7071

[0143] Table 10π / 2-BPSK Constellation Point Definitions (RACH Type Burst)

[0144] Even position 0 0.7071 0.7071 Even position 1 -0.7071 -0.7071 Odd position 0 -0.7071 0.7071 Odd position 1 0.7071 -0.7071

[0145] BPSK modulation is only used in RACH-type Burst, and its constellation points are defined as shown in Table 11.

[0146] Table 11 BPSK Constellation Point Definitions (RACH Type Burst)

[0147] 0 0.7071 0.7071 1 -0.7071 -0.7071

[0148] In one specific embodiment of the present invention, a root-raised cosine filter with a roll-off factor of 0.2 and a peak impulse response amplitude of 0.7457 is used to perform shaping filtering on the signal transmitted by the transmitter.

[0149] One specific embodiment, such as Figure 13 The present invention proposes an implementation structure of the transmission system on an FPGA chip.

[0150] First, the information source undergoes error correction coding operations through three steps: scrambling, CRC encoding, and LDPC encoding.

[0151] When the number of LDPC codewords is 2, the CRC encoding and LDPC encoding of the two codewords are implemented in parallel. The output results of the two branches are processed by the MUX module to form a single-port stream before being output to the next stage.

[0152] The error correction coding output is processed through modules such as bit interleaving, symbol mapping, Burst formation, and pulse shaping, and then through intermediate frequency and radio frequency modules to generate a wireless signal for transmission to the receiver module.

[0153] Furthermore, Table 12 lists the communication rates that can be obtained at the receiving end by the actual measurement of this implementation structure, where the number of LDPC codewords contained in each burst is 1.

[0154] Table 12 shows the measured communication rates under certain configurations.

[0155]

[0156] In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0157] It should also be noted that in the description of this invention, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0158] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A satellite communication data transmission system, characterized in that, include: Transmitter host computer, transmitter physical layer baseband module, digital upconversion module, digital downconversion module, receiver physical layer baseband module and receiver host computer; The host computer at the transmitter is used to transmit the first signal to the physical layer baseband module of the transmitter via Ethernet. The transmitter physical layer baseband module is used to process the first signal and send the processed second signal to the digital upconversion module; The digital up-conversion module is used to convert the second signal into a frequency and transmit the converted third signal through an antenna. The digital downconversion module is used to convert the fourth signal received by the antenna. The receiver physical layer baseband module is used to process the frequency-converted fifth signal and transmit the processed sixth signal to the host computer at the receiving end via an Ethernet interface. The transmitter physical layer baseband module includes An error correction coding unit is used to process the first signal received by the transmitter physical layer baseband module to obtain a first intermediate signal; A digital modulation unit is used to process the first intermediate signal to obtain a second signal; The first signal sent by the host computer at the transmitting end is output to the error correction coding unit. The error correction coding unit sequentially scrambles, performs CRC encoding, and LDPC encoding on the first signal to obtain a first intermediate signal. The digital modulation unit sequentially performs bit interleaving and symbol mapping processing on the first intermediate signal to output a second signal. The transmitter physical layer baseband module processes the first signal by selecting the operating mode according to the first signal; The data structure of the business data burst working mode includes preamble, frame header, block codewords and postamble; The data structure for random access burst working mode includes a preamble and block codewords; The preamble and postamble of the business data burst pattern are determined by the data-type random sequence, and the length of the preamble and postamble is determined by the block codeword length; The length of the leader in the random burst mode is determined by a random sequence, and the length of the leader consists of four random sequences of fixed length 100. The pilots for both the business data burst mode and the random burst mode are composed of random sequences. The pilot interval and number of pilots for the business data burst mode are determined by the length of the block codeword, while the pilot interval for the random burst mode is fixed. The scrambling includes bit-level scrambling of the first signal sent by the host computer at the transmitting end to obtain a scrambling output sequence; The CRC encoding includes performing CRC check calculation on the scrambled output sequence and appending the obtained CRC check sequence to the scrambled output sequence to obtain a CRC encoded output sequence. The LDPC encoding includes performing a check calculation on the CRC encoded output sequence according to the LDPC encoding algorithm, and appending the obtained LDPC check sequence to the CRC encoded output sequence to obtain an LDPC encoded output sequence as the first intermediate signal. The bit interleaving includes performing bit interleaving on each block codeword of the first intermediate signal using an in-row-out matrix interleaving method, wherein the number of columns of the interleaving matrix is ​​the order of the symbol mapping constellation diagram; When the number of LDPC codewords included in the first signal processed by the error correction coding unit is greater than 1, each LDPC codeword performs bit interleaving operation independently. The CRC encoding and LDPC encoding between the codewords can be implemented in parallel. The output result is processed by the aggregation module to form a single-ended output to the digital modulation unit.

2. The satellite communication data transmission system as described in claim 1, characterized in that, The transmitter physical layer baseband module is configured to have a random access burst working mode and a service data burst working mode. The transmitter physical layer baseband module, operating in random access burst mode, is used to process and transmit requests for establishing connections to the gateway in the transmitter's transmitted signals. The transmitter physical layer baseband module, operating in business data burst mode, is used to process and transmit data signals other than connection requests in the host computer's transmitted signals.

3. The satellite communication data transmission system as described in claim 1, characterized in that, The transmitter physical layer baseband module also includes a PLSC, which is used to determine the operating mode, signal modulation method, LDPC code length and code rate of the baseband module based on the first signal.

4. The satellite communication data transmission system as described in claim 1, characterized in that, In the business data burst mode, PLSC obtains symbol vectors by first-order Reed-Muller coding, content repetition, bit scrambling and π / 2-BPSK modulation of bits, and embeds them into the frame header field; In the random access burst mode, the PLSC maps bits into 100-bit random vectors and then performs π / 2-BPSK modulation, and the modulation result is filled into the preamble field.

5. The satellite communication data transmission system as described in claim 1, characterized in that, The symbol mappings include BPSK, π / 2-BPSK, QPSK, and 8PSK, whose constellation points lie on a circle of constant radius; in The 8PSK is used in the business data burst working mode; The BPSK is used in random access burst working mode; The QPSK is used in the business data burst working mode and / or the random access burst working mode; The π / 2-BPSK is used in the business data burst working mode and / or random access burst working mode.

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