Satellite Internet Fast and High-Precision Navigation and Positioning Method

Abstract

The present invention proposes a method for rapid and high-precision navigation and positioning in satellite Internet. The transmitting end modulates the navigation message and broadcasts it through the satellite Internet frequency band. By utilizing the advantages of multi-carrier modulation in satellite Internet, the I branch of QPSK is used for rapid parallel broadcast, and the acquisition of basic navigation and positioning parameters for the first time is improved from the second level to the millisecond level of single-wave position residence. The receiving end demodulates the received signal to obtain the navigation message. QPSK modulation is adopted, and the Q branch supporting high-precision measurement is separated from the I branch modulating the message. The Q branch is used for high-precision frequency offset estimation and time delay estimation. The I branch is used for rapid broadcast of the navigation message, which realizes both high-precision frequency and time delay measurement and rapid message broadcast.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation, and particularly to a method for rapid and high-precision navigation and positioning of satellite Internet. Background Art

[0002] With the upsurge of the construction of satellite Internet systems, navigation and positioning based on satellite Internet constellations has gradually become a research hotspot in the field of satellite navigation.

[0003] The beam range broadcast by satellite Internet constellations is relatively narrow, and generally multi-beam polling is required to achieve wide-area coverage. Suppose there are 1000 beams, and the dwell time of each beam is 5 ms, then the polling period is as long as 5 s. In addition, the influence of the satellite Internet constellation navigation message frame structure on the positioning time is mainly reflected in the acquisition time of positioning important information such as CED + GST (ephemeris and clock parameters and system time). If the basic parameters CED + GST required for satellite Internet navigation and positioning cannot be broadcast to users in a single beam, but need to be sent in multiple frames, then the time for users to receive all CED + GST information is relatively long. Suppose 10 frames of navigation messages need to be broadcast, then the total time for the first receipt of all CED + GST information is 50 s.

[0004] At the same time, the satellite Internet navigation and positioning signal is generally a burst signal, and users need to receive multiple frames to complete the first positioning, which requires relatively high channel conditions. If a certain frame of message is not received, it will affect the current positioning, and it will take another 50 s to perform positioning. The shortest acquisition time of the traditional GNSS message frame structure is about 18 s after normalizing the data rate to 50 bps. If the acquisition time of the basic parameters CED + GST of satellite Internet navigation and positioning can be reduced to the dwell time of a single beam (such as 5 ms), it will have important engineering application value and system innovation value.

[0005] In addition to the rapid broadcast of navigation messages, the satellite Internet navigation signal also needs to support high-precision Doppler and delay measurements to achieve satellite-ground pseudorange calculation, which requires the satellite Internet navigation signal to be compatible with the design of high-precision measurement systems. Summary of the Invention

[0006] Aiming at the problems of the long beam polling period in satellite Internet and the long time required to receive all navigation messages, as well as the high-precision measurement requirements in the prior art, the present invention proposes a method for rapid and high-precision navigation and positioning of satellite Internet, so as to achieve rapid positioning with millimeter-level message acquisition time and meter-level high-precision measurement.

[0007] The technical solution of the present invention is as follows:

[0008] A method for rapid and high-precision navigation and positioning of satellite Internet, comprising the following steps:

[0009] Step 1: Modulate the navigation message and broadcast it through the satellite Internet frequency band; including the following processes:

[0010] Step 1.1: Perform CRC check, channel coding, and interleaving operation on the navigation message to form a navigation message frame sequence ;

[0011] Step 1.2: Use the pseudo-random code to perform spread-spectrum modulation on the navigation message frame sequence after encoding and interleaving in Step 1.1 to generate the in-phase baseband signal; then perform QPSK modulation on the in-phase baseband signal obtained after spread-spectrum modulation and the Q-branch pilot signal to generate the navigation baseband complex sequence, where the Q-branch pilot signal does not modulate the message information;

[0012] Step 1.3: Perform subcarrier mapping on the navigation baseband complex sequence obtained in Step 1.2, use the IFFT operation, and perform the fusion of the navigation signal and the communication signal to obtain the CP-OFDM baseband time-domain waveform ; then perform up-conversion modulation on the obtained CP-OFDM baseband time-domain waveform and broadcast it through the satellite Internet frequency band;

[0013] Step 2: Demodulate the received signal to obtain the navigation message; specifically including the following processes:

[0014] Step 2.1: Perform down-conversion on the received signal, locally generate the Q-branch reference signal complex sequence at the same time, and use the IFFT operation on the Q-branch reference signal complex sequence to generate the reference signal CP-OFDM time-domain waveform;

[0015] Step 2.2: Perform time-domain correlation between the reference signal CP-OFDM time-domain waveform and the down-converted received signal to obtain the frequency offset estimation value and the integer delay estimation value; perform frequency-domain correlation between the reference signal CP-OFDM time-domain waveform and the down-converted received signal to obtain the fractional delay estimation value; obtain the total delay estimation value according to the integer delay estimation value and the fractional delay estimation value;

[0016] Step 2.3: According to the frequency offset estimation value and the total delay estimation value, perform correlation between the received signal after removing the frequency offset and the in-phase pseudo-code signal in the down-converted received signal, perform message symbol estimation according to the correlation value, perform de-interleaving and decoding check on the message symbol estimation, and obtain the demodulated navigation message;

[0017] Step 3: Complete high-precision navigation positioning according to the navigation message demodulated in Step 2 and the total delay estimation value.

[0018] Further, the specific process of Step 1.1 is:

[0019] (101): CRC check: Let the navigation message be , where represents the discrete serial number of the sequence. Additionally, let the CRC generation polynomial be , then the navigation message sequence after CRC check is: ;

[0020] (102): Channel coding: Convolutional or LDPC channel coding is performed on the navigation message sequence after CRC check. Let the convolutional or LDPC channel coding generation matrix be , then the encoded navigation message sequence is: ;

[0021] (103): Interleaving coding: Interleaving and framing are performed on the navigation message after channel coding. Let the interleaving matrix be , then the interleaved navigation message frame sequence is: .

[0022] Further, the specific process of step 1.2 is:

[0023] (201): Spread spectrum modulation is performed on the navigation message frame sequence using a pseudo-random code. Let the pseudo-random code sequence of the I branch be , then the baseband signal of the I branch after spread spectrum modulation is: ;

[0024] (202): QPSK modulation: QPSK modulation is performed on the baseband signal of the I branch obtained after spread spectrum modulation and the pilot signal of the Q branch. Let the pilot signal of the Q branch be , then the complex baseband sequence of the navigation after QPSK modulation is: , where the superscript of represents the transmitting system, and the subscript represents the navigation baseband, represents the imaginary unit.

[0025] Further, the specific process of step 1.3 is:

[0026] (301): Subcarrier mapping is performed on the complex baseband sequence of the navigation obtained after QPSK modulation. Let the number of available subcarriers for navigation be , the satellite Internet beam dwell time be , and the total number of OFDM symbols within the dwell time be , then the number of navigation messages mapped to each subcarrier is: , where is the spreading ratio;

[0027] (302): Perform IFFT operation on the QPSK modulation sequence after subcarrier mapping to generate an OFDM symbol, and insert a cyclic redundancy CP in the OFDM symbol to generate a CP-OFDM navigation baseband waveform , where is the number of points of the inverse Fourier transform, is the OFDM symbol period, represents the time;

[0028] (303): According to the satellite Internet configuration, the navigation signal can be generated together with the communication signal to form a CP-OFDM baseband time-domain waveform, realizing signal-level fusion; the fused CP-OFDM baseband time-domain waveform is as follows:

[0029]

[0030] where is the communication baseband complex sequence, occupying subcarriers, and the navigation baseband complex sequence occupies subcarriers;

[0031] (304): Perform up-conversion modulation on the obtained CP-OFDM baseband time-domain waveform to obtain the up-conversion modulation signal as:

[0032]

[0033] where is the carrier frequency.

[0034] Furthermore, the specific process of step 2.1 is as follows:

[0035] (401): Establish a received signal model: Assume that after the transmitted signal passes through a Gaussian white noise propagation channel, the frequency offset is , and the time delay is , then the received signal after down-conversion is: , where is the amplitude, is the Gaussian white noise;

[0036] (402): Generate a reference signal: Generate a Q-branch reference signal complex sequence according to the Q-branch pilot signal: , perform IFFT operation on the Q-branch reference signal complex sequence to generate a reference signal CP-OFDM time-domain waveform: .

[0037] Furthermore, the specific process of step 2.2 is as follows:

[0038] (501): Frequency offset estimation and integer delay estimation: Perform time-domain correlation between the reference signal CP-OFDM time-domain waveform and the received signal, traverse the Doppler and integer delay ranges, and perform two-dimensional estimation of frequency offset and integer delay. The estimation method is as follows:

[0039] R r ( Delta f , tau ) = ifft [ fft ( S base r ( t ) ) fft ∗ ( S ref r ( t ) ) ]

[0040]

[0041] In the formula is the Fourier transform, is the Fourier transform of the conjugate, is the inverse Fourier transform, is the frequency offset estimated value, is the integer delay estimated value, represents the correlation value, represents the maximum value of the correlation value amplitude;

[0042] (502): Fractional delay estimation: Perform frequency-domain correlation algorithm between the reference signal CP-OFDM time-domain waveform and the received signal to obtain the fractional delay estimation:

[0043] Define an intermediate variable :

[0044]

[0045] represents the complex conjugate sequence of the Q-branch reference signal of the conjugate. Then the fractional delay estimated value is: In the formula is the complex phase angle calculation function, is the intermediate variable of the conjugate;

[0046] Add the integer delay and the fractional delay to obtain the total delay estimated value as: .

[0047] Further, the specific process of step 2.3 is:

[0048] (601): Message demodulation: Adjust the frequency and delay of the received signal and perform FFT operation to obtain the received sequence , correlate the received sequence with the I-branch pseudo-random code sequence, and the correlation value is expressed as: R d ata ( k ) = ifft [ fft ( Y ( k ) ) fft ∗ (C I ( k ) ) ] , according to the correlation value, perform message symbol estimation, then the message symbol estimated value is: where sign [ • ] is a sign operation function;

[0049] (602): Deinterleaving and decoding verification: The estimated value of the message symbol is deinterleaved and decoded to obtain the estimated value of the original modulated navigation message , where , , are respectively the CRC generation polynomial , the channel coding generation matrix , and the inverse matrix of the interleaving matrix .

[0050] Furthermore, in step 3, using the satellite Internet ephemeris and clock parameters and system time in the demodulated navigation message, combined with the total delay estimate value, the navigation positioning solution is completed.

[0051] In addition, the present invention also proposes an electronic device and a readable storage medium:

[0052] An electronic device includes a processor and a memory, and the memory is used to store one or more programs;

[0053] When the one or more programs are executed by the processor, the above method is implemented.

[0054] A readable storage medium stores a computer program, and when the computer program is executed by a processor, the above method is implemented.

[0055] Beneficial effects:

[0056] The present invention has the following advantages:

[0057] (1) The beam range broadcast by the satellite Internet constellation is relatively narrow and is generally a burst signal. If the basic positioning parameters required for the first positioning cannot be broadcast in a single wave position, it will lead to too long first positioning time, which is not conducive to the rapid positioning of the user terminal. The present invention utilizes the advantages of multi-carrier modulation of the satellite Internet for the message parameters required for navigation positioning, and uses the I branch of QPSK for fast parallel broadcast, so as to improve the first acquisition of basic navigation positioning parameters from the second level to the millisecond level of a single wave position residence. For example, through multi-carrier modulation, a 900-bit navigation message can be broadcast in about 240 sub-carriers, and the broadcast time is the residence time of a wave position. If it is 5 ms, then the acquisition time of the entire basic navigation positioning parameters is in the millisecond level.

[0058] (2) In addition to fast message broadcast, the satellite Internet constellation positioning signal also needs to support high-precision measurements, that is, support high-precision Doppler estimation and time delay estimation. For this purpose, the present invention uses QPSK modulation to demultiplex the Q branch for high-precision measurements from the I branch for modulating the message. The Q branch is used for high-precision frequency offset estimation and time delay estimation; the I branch is used for fast navigation message broadcast, thus achieving both high-precision frequency and time delay measurements and fast message broadcast.

[0059] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Brief Description of the Drawings

[0060] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0061] Figure 1 is the system principle block diagram of the present invention;

[0062] Figure 2 is the frequency estimation curve of the embodiment;

[0063] Figure 3 is the time delay estimation curve of the embodiment;

[0064] Figure 4 is the demodulation performance curve of the embodiment. Detailed Embodiment

[0065] The following details the embodiments of the present invention. The described embodiments are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0066] Figure 1 The principle block diagram of the satellite Internet fast high-precision navigation and positioning method proposed in this embodiment is detailed. The principle block diagram includes a modulation part and a demodulation part. Specifically, it includes the following steps:

[0067] Step 1: Modulate the navigation message and broadcast it through the satellite Internet frequency band; specifically, it includes the following process:

[0068] Step 1.1: Perform CRC check, channel coding, and interleaving operation on the navigation message to form a navigation message frame sequence; the specific process is as follows:

[0069] (101): CRC check: Let the navigation message be , where represents the discrete sequence number, and let the CRC generating polynomial be , then the navigation message sequence after CRC check is: ;

[0070] (102): Channel coding: The navigation message sequence after CRC check is subjected to channel coding such as convolution or LDPC. Let the generating matrix of convolution or LDPC channel coding be , then the coded navigation message sequence is: ;

[0071] (103): Interleaving coding: The navigation message after channel coding is interleaved and framed. Let the interleaving matrix be , then the interleaved navigation message frame sequence is: .

[0072] Step 1.2: The navigation message frame sequence after encoding, interleaving, and framing in Step 1.1 is spread-spectrum modulated using a pseudo-random code to generate an in-phase baseband signal; then the in-phase baseband signal obtained after spread-spectrum modulation is subjected to QPSK modulation with a quadrature-branch pilot signal, generating a navigation baseband complex sequence. The quadrature-branch pilot signal does not modulate the message information and supports high-precision Doppler measurement and time-delay measurement. The specific process is as follows:

[0073] (201): Spread-spectrum modulation of the navigation message frame sequence using a pseudo-random code: Let the in-phase pseudo-random code sequence be , then the in-phase baseband signal obtained after spread-spectrum modulation is: ;

[0074] (202): QPSK modulation: The in-phase baseband signal obtained after spread-spectrum modulation is subjected to QPSK modulation with a quadrature-branch pilot signal. Let the quadrature-branch pilot signal be , then the navigation baseband complex sequence obtained after QPSK modulation is: , where the superscript of represents the transmitting system, the subscript represents the navigation baseband, represents the imaginary unit.

[0075] Step 1.3: The navigation baseband complex sequence obtained in Step 1.2 is subjected to subcarrier mapping, using IFFT operation, and the navigation signal and communication signal are fused to obtain a CP-OFDM baseband time-domain waveform , and then the obtained CP-OFDM baseband time-domain waveform is up-converted and transmitted through the satellite Internet frequency band; the specific process is as follows:

[0076] (301): Perform subcarrier mapping on the navigation baseband complex sequence obtained after QPSK modulation. Assume the number of available navigation subcarriers is , the satellite Internet beam dwell time is , the total number of OFDM symbols within the dwell time is , then the number of navigation messages mapped to each subcarrier is: , is the spreading ratio, and the number of navigation messages broadcast within the single-wave dwell time is: .

[0077] (302): Perform IFFT operation on the QPSK modulation sequence after subcarrier mapping to generate OFDM symbols, and insert cyclic redundancy CP in the OFDM symbols to generate the CP-OFDM navigation baseband waveform , where is the number of points of the inverse Fourier transform, is the OFDM symbol period, represents the time instant.

[0078] (303): According to the satellite Internet configuration, the navigation signal and the communication signal can be jointly generated into the CP-OFDM baseband time-domain waveform to achieve signal-level fusion. Then the fused CP-OFDM baseband time-domain waveform is as follows:

[0079]

[0080] where is the communication baseband complex sequence, occupying subcarriers, and the navigation baseband complex sequence occupies subcarriers.

[0081] (304): Perform up-conversion modulation on the obtained CP-OFDM baseband time-domain waveform to obtain the up-conversion modulation signal as:

[0082]

[0083] where is the carrier frequency.

[0084] Step 2: Demodulate the received signal to obtain the navigation message; specifically, it includes the following processes:

[0085] Step 2.1: Perform down-conversion on the received signal. At the same time, locally generate the Q-branch reference signal complex sequence, and use the IFFT operation on the Q-branch reference signal complex sequence to generate the reference signal CP-OFDM time-domain waveform; the specific process is:

[0086] (401): Establish a received signal model. Assume that after the transmitted signal passes through the Gaussian white noise propagation channel, the frequency offset is , the time delay is , then the received signal after down-conversion is: , where is the amplitude, is the Gaussian white noise.

[0087] (402): Generate a reference signal: Generate a complex sequence of the Q-branch reference signal according to the Q-branch pilot signal: , perform an IFFT operation on the complex sequence of the Q-branch reference signal to generate a CP-OFDM time-domain waveform of the reference signal: .

[0088] Step 2.2: Perform time-domain correlation between the CP-OFDM time-domain waveform of the reference signal and the received signal to obtain a frequency offset estimation value and an integer time delay estimation value; perform frequency-domain correlation between the CP-OFDM time-domain waveform of the reference signal and the received signal to obtain a fractional time delay estimation value; the specific process is as follows:

[0089] (501): Frequency offset estimation and integer time delay estimation: Perform time-domain correlation between the CP-OFDM time-domain waveform of the reference signal and the received signal, traverse the Doppler and integer time delay ranges, and perform two-dimensional estimation of the frequency offset and the integer time delay. The estimation method is as follows:

[0090] R r ( Delta f , tau ) = ifft [ fft ( S base r ( t ) ) fft ∗ ( S ref r ( t ) ) ]

[0091]

[0092] In the formula is the Fourier transform, is the Fourier transform of the conjugate, is the inverse Fourier transform, is the frequency offset estimation value, is the integer time delay estimation value, represents the correlation value, represents the maximum value of the correlation value amplitude. The frequency offset estimation accuracy and the signal-to-noise ratio curve is shown in Figure 2 . It can be seen from the figure that when the signal-to-noise ratio is 0 dB, the frequency offset estimation accuracy is better than 0.5 Hz.

[0093] (502): Fractional time delay estimation: Perform a frequency-domain correlation algorithm between the CP-OFDM time-domain waveform of the reference signal and the received signal to obtain a fractional time delay estimation:

[0094] Define an intermediate variable :

[0095]

[0096] Denote the complex sequence of the Q-branch reference signal as the conjugate. Then the fractional delay estimation value is: , where is the complex phase angle calculation function, is the intermediate variable as the conjugate.

[0097] The sum of the integer delay and the fractional delay gives the total delay estimation value as: .

[0098] The delay estimation accuracy and the signal-to-noise ratio curve is shown in Figure 3 . It can be seen from the figure that when the signal-to-noise ratio is 0 dB, the delay estimation accuracy is better than 1 ns.

[0099] Step 2.3: According to the frequency offset estimation value and the delay estimation value, strip the frequency offset from the received signal and correlate it with the I-branch pseudo-code signal in the received signal, and perform message symbol estimation based on the correlation value, and perform deinterleaving and decoding verification on the message symbol estimation to obtain the demodulated navigation message; the specific process is as follows:

[0100] (601): Message demodulation: After adjusting the frequency and delay of the received signal and performing FFT operation, the received sequence is obtained. Correlate the received sequence with the I-branch pseudo-random code sequence, and the correlation value is expressed as: R d ata ( k ) = ifft [ fft ( Y ( k ) ) fft ∗ (C I ( k ) ) ] . According to the correlation value, perform message symbol estimation, and the message symbol estimation value is: , where sign [ • ] is the sign operation function.

[0101] The symbol error rate and the signal-to-noise ratio curve is shown in Figure 4 . It can be seen from the figure that when the signal-to-noise ratio is 3.15 dB, the symbol error rate is better than 2.60E-7.

[0102] (602): Deinterleaving and decoding verification: Deinterleave and decode verify the message symbol estimation value to obtain the estimated value of the original modulated navigation message, where , , are the inverse matrices of the CRC generation polynomial , the channel coding generation matrix , and the interleaving matrix respectively.

[0103] Step 3: Complete high-precision navigation positioning based on the navigation message demodulated in Step 2 and the total time delay estimation value. Specifically, by using the satellite Internet ephemeris and clock parameters and the system time in the demodulated navigation message, combined with the total time delay estimation value, fast and high-precision navigation positioning calculation can be completed by using the well-known techniques in the art.

[0104] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principle and spirit of the present invention.

Claims

1. A satellite Internet fast and high-precision navigation and positioning method, characterized in that: Including the following steps: Step 1: Modulate the navigation message and broadcast it through the satellite Internet frequency band; including the following processes: Step 1.1: Perform CRC check, channel coding, and interleaving operation on the navigation message to form a navigation message frame sequence ; Step 1.2: The navigation message frame sequence after encoding, interleaving, and framing in Step 1.1 is spread-spectrum modulated using a pseudo-random code to generate an in-phase baseband signal ; then the in-phase baseband signal obtained after spread-spectrum modulation is QPSK modulated with the Q-branch pilot signal to generate a navigation baseband complex sequence , where the Q-branch pilot signal does not modulate the message information; Step 1.3: Perform subcarrier mapping on the navigation baseband complex sequence obtained in Step 1.2, utilize IFFT operation, and perform the fusion of navigation signals and communication signals to obtain the CP-OFDM baseband time-domain waveform , then perform upconversion modulation on the obtained CP-OFDM baseband time-domain waveform and broadcast it through the satellite Internet frequency band; Step 2: Demodulate the received signal to obtain the navigation message; specifically including the following processes: Step 2.1: Down-convert the received signal to obtain the down-converted received signal , and simultaneously generate a complex sequence of Q-branch reference signals locally , and perform an IFFT operation on the complex sequence of Q-branch reference signals to generate a reference signal CP-OFDM time-domain waveform ; Step 2.2: Perform time-domain correlation on the time-domain waveform of the reference signal CP-OFDM and the received signal after downconversion to obtain a frequency offset estimation value and an integer delay estimation value ; perform frequency-domain correlation on the time-domain waveform of the reference signal CP-OFDM and the received signal after downconversion to obtain a fractional delay estimation value ; obtain a total delay estimation value based on the integer delay estimation value and the fractional delay estimation value ; Step 2.3: According to the frequency offset estimation value and the total time delay estimation value, strip the frequency offset from the received signal and correlate it with the I-branch pseudo-code signal in the down-converted received signal, estimate the message symbol according to the correlation value, perform deinterleaving and decoding verification on the message symbol estimation, and obtain the demodulated navigation message; Step 3: Complete high-precision navigation positioning according to the navigation message demodulated in Step 2 and the total time delay estimation value.

2. The satellite Internet fast high-precision navigation and positioning method according to claim 1, characterized in that: The specific process of Step 1.1 is: S101: CRC check: Assume the navigation message is , where represents the sequence discrete serial number. Another CRC generating polynomial is assumed to be . Then the navigation message sequence after CRC check is: ; S102: Channel coding: For the navigation message sequence after CRC check perform channel coding such as convolution or LDPC. Assume the generating matrix of the channel coding such as convolution or LDPC is , then the encoded navigation message sequence is: ; S103: Interleaving Encoding: Perform interleaving and framing on the navigation message after channel coding. Assume the interleaving matrix is , then the interleaved navigation message frame sequence is: .

3. A satellite Internet fast and high-precision navigation and positioning method according to claim 1, characterized in that: The specific process of Step 1.2 is: S201: Spread spectrum modulation is performed on the navigation message frame sequence using a pseudo-random code : Assume that the pseudo-random code sequence of the I branch is , then the baseband signal of the I branch obtained after spread spectrum modulation is: ; S202: QPSK Modulation: Perform QPSK modulation on the I-branch baseband signal obtained after spreading modulation and the Q-branch pilot signal. Let the Q-branch pilot signal be . Then, the navigation baseband complex sequence obtained after QPSK modulation is: . In the formula, the superscript of represents the transmitting system, the subscript represents the navigation baseband, and represents the imaginary unit.

4. The satellite Internet rapid high-precision navigation and positioning method according to claim 1, wherein: The specific process of Step 1.3 is: S301: Perform subcarrier mapping on the navigation baseband complex sequence obtained after QPSK modulation. Assume the number of available navigation subcarriers is , the satellite Internet beam dwell time is , the total number of OFDM symbols within the dwell time is , then the number of navigation telegrams mapped to each subcarrier is: , where is the spreading ratio; S302: Perform an IFFT operation on the QPSK modulation sequence after subcarrier mapping to generate an OFDM symbol, and insert a cyclic redundancy CP into the OFDM symbol to generate a CP-OFDM navigation baseband waveform , where is the number of points of the inverse Fourier transform, is the OFDM symbol period, represents the time; S303: According to the satellite Internet configuration, the navigation signal and the communication signal can be uniformly generated into a CP-OFDM baseband time-domain waveform to achieve signal-level fusion; the fused CP-OFDM baseband time-domain waveform is as follows: Among them is a communication baseband complex sequence, occupying subcarriers, and the navigation baseband complex sequence occupies subcarriers; S304: Perform up-conversion modulation on the obtained CP-OFDM baseband time-domain waveform to obtain the up-conversion modulation signal as: wherein is the carrier frequency.

5. The satellite Internet fast high-precision navigation and positioning method according to claim 1, wherein: The specific process of Step 2.1 is: S401: Establish a received signal model: Assume that after the transmitted signal passes through the propagation channel, the frequency offset is , and the time delay is . Then the received signal after down-conversion is: , where is the amplitude, is the noise; S402: Generate a reference signal: Generate a complex sequence of Q-branch reference signals based on the Q-branch pilot signals: , represents the imaginary unit; perform an IFFT operation on the complex sequence of Q-branch reference signals to generate a reference signal CP-OFDM time-domain waveform: , is the number of points of the inverse Fourier transform, is the OFDM symbol period, represents time.

6. The satellite Internet rapid high-precision navigation and positioning method according to claim 1, characterized in that: The specific process of Step 2.2 is: S501: Frequency offset estimation and integer time delay estimation: Correlate the time domain waveform of the reference signal CP-OFDM with the down-converted received signal in the time domain to perform two-dimensional estimation of the frequency offset and the integer time delay. The estimation method is as follows: where is the Fourier transform, is the Fourier transform of the conjugate, is the inverse Fourier transform, is the frequency offset estimate, is the integer time delay estimate, represents the correlation value, represents the maximum value of the magnitude of the correlation value; is the frequency offset after the transmitted signal passes through the propagation channel, is the time delay after the transmitted signal passes through the propagation channel; S502: Fractional time delay estimation: Perform a frequency-domain correlation algorithm on the reference signal CP-OFDM time-domain waveform and the down-converted received signal to obtain the fractional time delay estimation: Define intermediate variables : denote the conjugate of the complex sequence of the Q-branch reference signal ; then the fractional delay estimation value is as follows: where is a complex phase calculation function, is an intermediate variable is the conjugate of, is the number of inverse Fourier transform points, is the OFDM symbol period, represents time; Adding the integer time delay and the fractional time delay gives the total time delay estimate as: .

7. The satellite Internet fast high-precision navigation and positioning method according to claim 1, wherein: The specific process of Step 2.3 is: S601: Demodulating the telegram: After adjusting the frequency and time delay of the received signal and performing FFT operation, a received sequence is obtained , correlating the received sequence with the pseudo-random code sequence of the I branch , and the correlation value is expressed as: , estimating the telegram symbol according to the correlation value to obtain the estimated value of the telegram symbol is: , where is the sign operation function; S602: Deinterleaving and decoding verification: The estimated value of the message symbols is deinterleaved and decoded for verification to obtain the estimated value of the original modulated navigation message , where , , are respectively the CRC generating polynomial , the channel coding generating matrix , and the inverse matrix of the interleaving matrix .

8. The satellite Internet fast high-precision navigation and positioning method according to claim 1, characterized in that: In Step 3, use the satellite Internet ephemeris and clock parameters and the system time in the demodulated navigation message, combined with the total time delay estimation value, to complete the navigation positioning calculation.

9. An electronic device, comprising a processor and a memory, the memory being configured to store one or more programs; characterized in that: When the one or more programs are executed by the processor, the method according to any one of claims 1 to 8 is implemented.

10. A readable storage medium stores a computer program, characterized in that: When the computer program is executed by the processor, the method according to any one of claims 1 to 8 is implemented.

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