Navigation receiving method and navigation receiver for CP-OFDM signal

Abstract

The present application belongs to the technical field of navigation receiver, and relates to a navigation receiving method and a navigation receiver of CP-OFDM signal. The method comprises the following processes: the received CP-OFDM signal is down-converted to obtain an intermediate frequency signal; the intermediate frequency signal is sent to a non-coherent delay tracking loop, the non-coherent delay tracking loop comprising a leading branch, a current branch and a lagging branch; the leading branch and the lagging branch process the intermediate frequency signal to obtain the amplitude of coherent integration respectively; when processing the intermediate frequency signal, the two branches generate a local copy signal first, and the guard interval of the local copy signal is filled with zero value; the signal propagation time delay is calculated according to the amplitude of coherent integration of the two branches; the noise is removed to obtain a filtered time delay value; the time delay experienced by the received signal is estimated based on the filtered time delay value, and the position information of the receiver is estimated. The problem of the influence of the cyclic prefix and adjacent frequency points in the CP-OFDM signal on the navigation tracking precision is solved.

Description

Technical Field

[0001] This invention belongs to the field of navigation receiver technology, and specifically relates to a navigation receiving method and a navigation receiver for CP-OFDM signals. Background Technology

[0002] With the rapid development of autonomous driving, 5G, and internet technologies, especially the rise of concepts such as the Internet of Things (IoT) and smart cities, the demand for location-based services (LBS) is constantly increasing. Currently, the Global Navigation Satellite System (GNSS) can provide high-precision location services outdoors, achieving rapid development thanks to its high-precision positioning, navigation, and timing (PNT) capabilities and ubiquitous, high-speed information transmission capabilities. However, due to factors such as weak navigation signal power, susceptibility to physical space environment interference, low navigation message transmission rate, and limited navigation service types, GNSS cannot yet meet users' personalized needs in complex environments, particularly in terms of positioning accuracy, serviceability, and anti-interference performance, which significantly limits the application scope and depth of satellite navigation.

[0003] The rapid development of low-Earth orbit (LEO) satellites and broadband communications has provided an opportunity for the development of integrated communication and navigation technologies. Orthogonal Frequency Division Multiplexing (OFDM), due to its high spectral efficiency and good resistance to multipath interference, is widely used in Starlink and terrestrial cellular networks to enhance signal multipath resistance. Therefore, broadcasting OFDM-based LEO broadband constellations is a future development trend. Opportunistic navigation based on CP-OFDM communication signals is a hot area for improving PNT (Portable Navigation) services.

[0004] Current opportunistic navigation receivers based on CP-OFDM suffer from interference between the cyclic prefix and adjacent subcarriers. Since the impact of the cyclic prefix (CP) on navigation tracking accuracy was not previously considered, tracking performance has been reduced. Summary of the Invention

[0005] The purpose of this invention is to provide a navigation receiving method and a navigation receiver for CP-OFDM signals, which solves the problem that the cyclic prefix and adjacent frequency points in CP-OFDM signals affect navigation tracking accuracy.

[0006] This invention is achieved through the following technical solution:

[0007] This invention discloses a navigation reception method for CP-OFDM signals, comprising the following steps:

[0008] S1. Down-convert the received CP-OFDM signal to obtain an intermediate frequency signal;

[0009] S2. The intermediate frequency signal is sent into the non-coherent delay tracking loop, which includes a leading branch, an instantaneous branch, and a lagging branch.

[0010] The lead branch processes the intermediate frequency signal to obtain the amplitude of the lead branch coherent integral;

[0011] The lag branch processes the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch;

[0012] When processing intermediate frequency signals, leading and lagging branches must first locally replicate the signal, and the guard interval of the locally replicated signal is filled with zero value;

[0013] S3. Calculate the signal propagation delay based on the amplitude of the coherent integral of the leading branch and the amplitude of the coherent integral of the lagging branch.

[0014] S4. Remove noise from the signal propagation delay to obtain the filtered delay value;

[0015] The received signal delay is estimated based on the filtered delay value, and the receiver's position information is then estimated based on the received signal delay.

[0016] Furthermore, in S1, the intermediate frequency signal is obtained by mixing the received CP-OFDM signal, and the calculation expression is as follows:

[0017]

[0018] Among them, s RS (t) represents the reference signal used for navigation, s COM (t) represents the communication signal, f e and It refers to the frequency offset and phase shift of the signal after intermediate frequency mixing at the receiver; s IF (t) represents the intermediate frequency signal; j represents the imaginary unit, and t represents time;

[0019] S RS (t) is pre-defined according to the protocol; S COM (t) is unknown.

[0020] Furthermore, in S2, the lead branch processes the intermediate frequency signal to obtain the amplitude of the coherent integral of the lead branch. The specific process is as follows:

[0021] (1) Generate a local copy signal;

[0022] During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values.

[0023] (2) The locally copied signal is delayed by a delay time of τ-d. When the locally copied signal is coherently integrated with the intermediate frequency signal, the integration time of each symbol is ensured to be T. u The result of the coherent integral is obtained;

[0024] Where τ is the estimated time delay, d is the time interval between the leading branch and the instantaneous branch; T u Represents the duration of useful symbols in OFDM;

[0025] (3) The result of the coherent integration is fed into the integration zeroing filter to obtain the amplitude of the coherent integration of the lead branch.

[0026] Furthermore, in S2, the lag branch processes the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch. The specific process is as follows:

[0027] (1) Generate a local copy signal;

[0028] During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values.

[0029] (2) The locally copied signal is delayed by a delay time of τ+d. When the locally copied signal is coherently integrated with the intermediate frequency signal, the integration time of each symbol is ensured to be T. u The result of the coherent integral is obtained;

[0030] Where τ is the estimated time delay, d is the time interval between the leading branch and the instantaneous branch; T u Represents the duration of useful symbols in OFDM;

[0031] (3) The result of the coherent integration is fed into the integration zeroing filter to obtain the amplitude of the coherent integration of the lead branch.

[0032] Furthermore, in S3, the expression for calculating the signal propagation delay is:

[0033]

[0034] In the formula, τ meas K represents the signal propagation delay. RSThese are the normalized parameters of the NELP delay phase detector, calculated based on the S-curve of the navigation signal; V E V is the amplitude of the coherent integral of the leading branch. L This represents the amplitude of the coherent integral of the lagging branch.

[0035] Furthermore, in S4, the receiver's position information is estimated based on the time delay experienced by the received signal, specifically as follows:

[0036] The relative distance between the receiver and the transmitter is obtained based on the time delay experienced by the received signal. The position information of the receiver is estimated using the known position of the transmitter and the relative distance.

[0037] Furthermore, the processing procedure in the instantaneous branch is as follows:

[0038] (1) Generate a local copy signal;

[0039] During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values.

[0040] (2) Delay the local copy signal. The delay time of the local copy signal is τ. When the local copy signal and the intermediate frequency signal are coherently integrated, ensure that the integration time of each symbol is Tu to obtain the result of coherent integration.

[0041] Where τ is the estimated time delay, d is the time interval between the leading branch and the instantaneous branch; T u Represents the duration of useful symbols in OFDM;

[0042] (3) The result of the coherent integration is fed into the integration zeroing filter to obtain the instantaneous branch coherent integration;

[0043] (4) Estimate the frequency of the intermediate frequency signal based on the phase change of two adjacent coherent integrals.

[0044] Furthermore, the locally replicated signal uses signals known in the OFDM reference signals: broadcast signals, channel quality estimation signals, and demodulation reference signals in various physical channels.

[0045] The present invention also discloses a navigation receiver for CP-OFDM signals, including a signal receiver, a downconverter, a noncoherent delay tracking loop, a discriminator in a delay-locked loop, a low-pass filter, and a digitally controlled oscillator for a reference signal;

[0046] Incoherent delay tracking loops include leading branches, immediate branches, and lagging branches;

[0047] A downconverter is used to downconvert the received CP-OFDM signal to obtain an intermediate frequency signal;

[0048] The lead branch is used to process the intermediate frequency signal to obtain the amplitude of the coherent integral of the lead branch;

[0049] The lag branch is used to process the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch;

[0050] The discriminator in the delay-locked loop is used to calculate the signal propagation delay based on the amplitude of the coherent integral of the leading and lagging branches;

[0051] A low-pass filter is used to remove noise from the signal propagation delay and obtain the filtered delay value.

[0052] A numerically controlled oscillator for the reference signal is used to estimate the time delay experienced by the received signal based on the filtered time delay value;

[0053] The estimation module estimates the receiver's position information based on the time delay experienced by the received signal.

[0054] Furthermore, the navigation receiver also includes a frequency-locked loop discriminator for stably tracking frequency deviations in the intermediate frequency signal.

[0055] Compared with the prior art, the present invention has the following beneficial technical effects:

[0056] This invention discloses a navigation reception method for CP-OFDM signals. By filling the OFDM guard interval of the navigation receiver with zero values, the influence of cyclic prefix and adjacent subcarriers on the tracking accuracy of the navigation receiver is avoided, and the tracking accuracy is significantly improved. Attached Figure Description

[0057] Figure 1 This is a system block diagram of CP-OFDM; the upper part represents the CP-OFDM signal generation structure, the middle part represents the radio channel, and the lower part represents the CP-OFDM-based navigation receiver.

[0058] Figure 2 This refers to the zero-padding correlation (ZPC) process.

[0059] Figure 3 Comparison of tracking accuracy for several different CP-OFDM correlators;

[0060] Figure 4 The DLL tracking accuracy is given for different navigation reception strategies under three NR signals. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0062] The detailed description of the embodiments of the present invention provided in the following figures is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the figures and embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0063] This invention first describes the process of generating a CP-OFDM signal on the transmitter side, including the following steps:

[0064] like Figure 1 As shown, S101 and the upper layer of the transmitting station modulate the communication data stream (BitsStream) and the reference signal (ReferenceSignal) (QAM quadrature amplitude modulation, QPSK: quadrature phase shift keying);

[0065] S102. Perform serial-to-parallel conversion on the obtained serial modulation symbols to obtain parallel modulation symbols c. n,k n represents the symbol number, and k represents the subcarrier number;

[0066] S103, Modulate symbol c n,k Perform an inverse fast Fourier transform to obtain the useful OFDM signal s u (t):

[0067]

[0068] Where K represents the number of subcarriers; j represents the unit imaginary number; Δf represents the subcarrier interval; t represents time; T u Represents the duration of useful symbols in OFDM;

[0069] u T (t) represents a window function with duration T, i.e.:

[0070]

[0071] The parallel data obtained from the inverse fast Fourier transform is serialized to obtain the OFDM modulated signal s. u (t).

[0072] S104. Generate a cyclic prefix (CP), where CP is a part of the OFDM signal;

[0073]

[0074] S105. Add CP to the front end of the OFDM modulation signal to obtain the CP-OFDM signal:

[0075]

[0076] Where Tsym is the duration of a CP-OFDM symbol. The expression is:

[0077] T sym =T u +T g (5)

[0078] Among them, T u T represents the duration of the useful symbol in OFDM. g This represents the duration of the OFDM cyclic prefix;

[0079] The CP-OFDM signal generated by the transmitter is sent to the receiver via a radio channel. The radio channel generally has the following effects on the signal: path loss, Doppler shift, and multipath effect.

[0080] The purpose of this invention is to overcome the system content interference present in existing CP-OFDM navigation systems and to provide a zero-padding correlation (ZPC) receiver to avoid the impact of cyclic prefixes and interference between adjacent subcarriers on navigation performance. ZPC is the core module of the CP-OFDM navigation receiver, and its purpose is to achieve interference-free navigation performance from multi-frequency CP-OFDM signals.

[0081] Zero-padding correlation refers to adding several zero values ​​to the end of a signal to increase its length before performing correlation operations.

[0082] like Figure 1 As shown, the top diagram represents the transmitter, the middle diagram represents the signal channel, and the bottom diagram represents the navigation receiver.

[0083] The receiver tracks the received CP-OFDM signal and estimates its propagation delay. The specific process is as follows:

[0084] S1. Down-convert the received signal to obtain an intermediate frequency signal:

[0085]

[0086] Among them, sR (t) is the signal received by the receiver, f local It is the frequency of the local mixing crystal oscillator, s RS (t) Reference signal used for navigation, s COM (t) is an unknown communication signal, f e and It refers to the frequency offset and phase shift of the signal after the receiver has undergone intermediate frequency mixing.

[0087] The intermediate frequency signal contains a reference signal S used for navigation. RS (t) and the communication signal S used for communication COM (t); S RS (t) is predefined according to the protocol; S COM Since (t) is unknown, we should try to avoid its impact on signal delay estimation.

[0088] S2. The intermediate frequency signal is fed into the non-coherent early minus late power (NELP) loop to estimate the signal delay. NELP contains three branches: lead branch, instant branch, and lag branch.

[0089] The time delays of the locally replicated signals in the leading branch, the immediate branch, and the lagging branch are τ-d, τ, and τ+d, respectively.

[0090] like Figure 2 As shown, the signal correlation operation process in the lead branch is introduced first:

[0091] (1) Generate a local copy signal;

[0092] During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values.

[0093] (2) The local copy signal is delayed, and the delay time of the signal is τ-d (where τ is the estimated time delay and d is the time interval between the leading branch and the instantaneous branch). When the local copy signal and the received signal are coherently integrated, the integration time of each symbol must be Tu; that is, for the cyclic prefix part, no correlation integration is performed and the cyclic prefix is ​​ignored.

[0094] (3) Then the result of the coherent integration is fed into the Integral Dump Filter (I&D) to obtain the amplitude V of the coherent integration of the lead branch. E .

[0095] The locally replicated signal uses known signals from the OFDM reference signals: broadcast signals, demodulation reference signals in various physical channels, and channel quality estimation signals.

[0096] Next, let's introduce the signal correlation operation process in the lagging branch:

[0097] (1) Generate a local copy signal;

[0098] During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values.

[0099] (2) Delay the locally copied signal. The delay time of the signal is τ+d (where τ is the estimated time delay and d is the time interval between the leading branch and the instantaneous branch). When the locally copied signal and the received signal are coherently integrated, ensure that the integration time of each symbol is Tu to obtain the result of the coherent integration.

[0100] (3) Then the result of the coherent integration is fed into the integration zeroing filter to obtain the amplitude V of the coherent integration of the lag branch. L .

[0101] S3. Based on the amplitude V of the coherent integral of the leading and lagging branches. E and V L It is possible to calculate the propagation delay τ of the received signal. meas :

[0102]

[0103] In the formula, K RS It is the normalized parameter of the NELP delay phase detector (DLLDiscriminator), which is calculated based on the S-curve of the navigation signal.

[0104] S4. The measured signal propagation delay τ meas The signal is fed into a low-pass filter (LPF) to remove noise and obtain the filtered time delay value τ. f A numerically controlled oscillator (NCO) with reference signal can stably estimate the time delay τ experienced by the received signal. est This allows for the estimation of information such as the receiver's location.

[0105] Specifically, based on the time delay τ experienced by the received signal est The relative distance between the receiver and the transmitter can be obtained. Using the known position of the transmitter and the relative distance, the position information of the receiver can be estimated.

[0106] Even better, such as Figure 1 As shown, in addition to the incoherent delay tracking loop, the CP-OFDM receiver also includes a frequency-locked loop discriminator (FLL discriminator) to stably track the frequency deviation in the intermediate frequency signal.

[0107] The processing procedure in the instantaneous branch is as follows:

[0108] (1) Generate a local copy signal; during the generation process, the modulation symbol of the reference signal of the local copy signal is consistent with the transmitted signal, and during the construction of the cyclic prefix, the guard interval of the local copy signal is filled with zero value;

[0109] (2) Delay the locally copied signal for a delay time of τ. When coherently integrating the locally copied signal with the received signal, ensure that the integration time of each symbol is Tu to obtain the result of coherent integration.

[0110] (3) Then the result of the coherent integration is fed into the integration zeroing filter to obtain the instantaneous branch coherent integration.

[0111] (4) The frequency of the intermediate frequency signal can be estimated by the phase change of two adjacent coherent integrals.

[0112] As shown in the figure, corresponding to the above method, the present invention discloses a navigation receiver for CP-OFDM signals, including a signal receiver, a downconverter, a noncoherent delay tracking loop, a discriminator in a delay-locked loop, a low-pass filter, and a digitally controlled oscillator for a reference signal.

[0113] Incoherent delay tracking loops include leading branches, immediate branches, and lagging branches;

[0114] A downconverter is used to downconvert the received CP-OFDM signal to obtain an intermediate frequency signal;

[0115] The lead branch is used to process the intermediate frequency signal to obtain the amplitude of the coherent integral of the lead branch;

[0116] The lag branch is used to process the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch;

[0117] The discriminator in the delay-locked loop is used to calculate the signal propagation delay based on the amplitude of the coherent integral of the leading and lagging branches;

[0118] A low-pass filter is used to remove noise from the signal propagation delay and obtain the filtered delay value.

[0119] A numerically controlled oscillator for the reference signal is used to estimate the time delay experienced by the received signal based on the filtered time delay value;

[0120] The estimation module estimates the receiver's position information based on the time delay experienced by the received signal.

[0121] The features and performance of the present invention will be further described in detail below with reference to verification examples.

[0122] Verification Example 1: The Impact of ZPC Correlation Receivers on Navigation Performance

[0123] The settings for transmitting signals and receiving receivers can be divided into the following three cases:

[0124] (1) The transmitted signal is CP-OFDM, and the locally copied signal of the receiver is also CP-OFDM. The integration time of each OFDM symbol is Tsym.

[0125] (2) The transmitted signal is CP-OFDM, and the receiver uses ZPC, that is, the local copy signal replaces CP with zero value filling, and the integration time of each OFDM symbol is Tu;

[0126] (3) The transmitted signal is CP-OFDM, but it only contains reference signals for navigation and does not contain communication signals. The receiver uses ZPC.

[0127] Simulate navigation systems with different configurations based on the schematic diagram of the OFDM navigation system, and estimate the code ring tracking accuracy of different configurations.

[0128] Experimental results are as follows Figure 3 As shown, the tracking accuracy using configuration (1) is the lowest because the CP and adjacent frequency signals interfere with the tracking accuracy of the code tracking loop; configuration (2) and configuration (3) have the same tracking accuracy, which shows that the ZPC receiver avoids the influence of CP and adjacent subcarriers on the code tracking loop.

[0129] Verification Example 2: Comparison of Tracking Performance between ZPC Receiver and Other Receivers

[0130] This invention assumes that the CP-OFDM signal uses a common 5G NR signal and utilizes its reference signal to provide navigation services. The performance differences between the ZPC receiver and other typical NR navigation receivers are demonstrated through a comparison of tracking accuracy. The ZPC receiver is a cooperative navigation receiver that uses all detectable signal components as locally replicated signals, including the Synchronization Block (SSB), Channel State Information Reference Signal (CSI-RS), and Demodulation Reference Signals (DMRS) in the Physical Downlink Shared Channel (PDSCH) and Physical Downlink Control Channel (PDCCH).

[0131] Shamaei first proposed an NR receiver that uses only the SSB signal. This reception strategy ignores other available navigation signals and does not consider low-Earth orbit (LEO) navigation scenarios. Neinavaie introduced a cognitive (CON) method for identifying navigation reference signals for similar LEO OFDM signals, but did not consider the effect of the cyclic prefix.

[0132] In this implementation, three NR signal configurations were used:

[0133] Signal 1: The subcarrier spacing is 15kHz, there are 120 subcarriers, the PDSCH bandwidth is 1.8MHz, and the corresponding center frequency is located at zero frequency. Each subframe contains 5 time slots, and the reference demodulation signal DMRS additional position value is 0;

[0134] Signal 2: It has the same bandwidth as Signal 1, but the spectral center of PDSCH has shifted from zero frequency to 260Δf;

[0135] Signal 3: Based on Signal 1, the PDSCH bandwidth is increased from 1.8MHz to 10.62MHz, the number of time slots in each subcarrier is increased from 5 to 9, and the demodulation reference signal is increased from 0 to 1. Therefore, in each NR frame, the resource elements of the reference signal are increased from 830 to 6850, and the power of the reference signal is increased.

[0136] like Figure 4 As shown, the DLL tracking accuracy of different navigation reception strategies under three NR signals was compared. The experimental results revealed four key findings:

[0137] (1) The SSB navigation receiver (proposed by Shamaei) exhibits the same tracking performance for different NR signals. This receiver only uses the SSB signal, so changes in PDSCH do not affect its tracking performance.

[0138] (2) The ZPC receiver proposed in this invention achieves higher tracking accuracy than the SSB receiver. This improvement stems from the full utilization of all known reference signals, including DMRS in SSB, PDCCH and PDSCH, as well as CSI-RS.

[0139] (3) Compared to the CON receiver, the ZPC receiver significantly improves tracking accuracy under the same NR signal. This is because the CON receiver does not consider cyclic prefix (CP) processing, resulting in noise caused by CP. Furthermore, the Physical Broadcast Channel (PBCH) changes over time, and the CON receiver cannot recognize the PBCH signal.

[0140] (4) By using different NR configurations, the tracking accuracy of ZPC can be significantly improved. This is because navigation signals exhibit different PSD and CNR under different NR configurations. Therefore, base stations can flexibly configure NR signals according to navigation requirements.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A navigation receiving method for CP-OFDM signals, characterized in that, The process includes the following: S1. Down-convert the received CP-OFDM signal to obtain an intermediate frequency signal; S2. The intermediate frequency signal is sent into the non-coherent delay tracking loop, which includes a leading branch, an instantaneous branch, and a lagging branch. The lead branch processes the intermediate frequency signal to obtain the amplitude of the lead branch coherent integral; The lag branch processes the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch; When processing intermediate frequency signals, leading and lagging branches must first locally replicate the signal, and the guard interval of the locally replicated signal is filled with zero value; S3. Calculate the signal propagation delay based on the amplitude of the coherent integral of the leading branch and the amplitude of the coherent integral of the lagging branch. S4. Remove noise from the signal propagation delay to obtain the filtered delay value; The received signal delay is estimated based on the filtered delay value, and the receiver's position information is estimated based on the received signal delay. In S2, the lead branch processes the intermediate frequency signal to obtain the amplitude of the lead branch coherent integral. The specific process is as follows: (1) Generate a local copy signal; During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values. (2) Delay the local copy signal. The delay time of the local copy signal is: -d ensures that the integration time for each symbol is [value missing] when coherently integrating the locally copied signal with the intermediate frequency signal. The result of the coherent integral is obtained; in, The estimated time delay is given by d, where d is the time interval between the leading branch and the immediate branch. Represents the duration of useful symbols in OFDM; (3) The result of the coherent integration is fed into the integration zeroing filter to obtain the amplitude of the coherent integration of the lead branch; In S2, the lag branch processes the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch. The specific process is as follows: (1) Generate a local copy signal; During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values. (2) Delay the local copy signal. The delay time of the local copy signal is: +d, when coherently integrating the locally copied signal with the intermediate frequency signal, ensure that the integration time for each symbol is... The result of the coherent integral is obtained; (3) The result of the coherent integration is fed into the integration zeroing filter to obtain the amplitude of the coherent integration of the lag branch; The processing procedure in the instantaneous branch is as follows: (1) Generate a local copy signal; During the generation process, the modulation symbol of the reference signal of the locally copied signal is consistent with that of the transmitted signal. During the construction of the cyclic prefix, the guard interval of the locally copied signal is filled with zero values. (2) Delay the local copy signal. The delay time of the local copy signal is: When performing coherent integration between the locally replicated signal and the intermediate frequency signal, ensure that the integration time of each symbol is Tu to obtain the result of the coherent integration; (3) The result of the coherent integration is fed into the integration zeroing filter to obtain the instantaneous branch coherent integration; (4) Estimate the frequency of the intermediate frequency signal based on the phase change of two adjacent coherent integrals.

2. The navigation receiving method for CP-OFDM signals according to claim 1, characterized in that, In S1, the intermediate frequency signal is obtained by mixing the received CP-OFDM signal, and the calculation expression is: Among them, s RS (t) represents the reference signal used for navigation, s COM (t) represents the communication signal, f e and e It refers to the frequency offset and phase shift of the signal after intermediate frequency mixing at the receiver; s IF (t) represents the intermediate frequency signal; j represents the imaginary unit, and t represents time; S RS (t) is pre-defined according to the protocol; S COM (t) is unknown.

3. The navigation receiving method for CP-OFDM signals according to claim 1, characterized in that, In S3, the expression for calculating the signal propagation delay is: In the formula, meas K represents the signal propagation delay. RS These are the normalized parameters of the NELP delay discriminator, calculated based on the S-curve of the navigation signal; V E V is the amplitude of the coherent integral of the leading branch. L This represents the amplitude of the coherent integral of the lagging branch.

4. The navigation receiving method for CP-OFDM signals according to claim 1, characterized in that, In S4, the receiver's position information is estimated based on the time delay experienced by the received signal, specifically as follows: The relative distance between the receiver and the transmitter is obtained based on the time delay experienced by the received signal. The position information of the receiver is estimated using the known position of the transmitter and the relative distance.

5. A navigation receiving method for CP-OFDM signals according to claim 1, characterized in that, The locally replicated signal uses known signals from the OFDM reference signals: broadcast signals, channel quality estimation signals, and demodulation reference signals in various physical channels.

6. A navigation receiver for a CP-OFDM signal that implements the navigation reception method for a CP-OFDM signal according to any one of claims 1-5, characterized in that, It includes a signal receiver, a downconverter, a noncoherent delay tracking loop, a discriminator in the delay-locked loop, a low-pass filter, and a digitally controlled oscillator for the reference signal; Incoherent delay tracking loops include leading branches, immediate branches, and lagging branches; A downconverter is used to downconvert the received signal to obtain an intermediate frequency signal. The lead branch is used to process the intermediate frequency signal to obtain the amplitude of the coherent integral of the lead branch; The lag branch is used to process the intermediate frequency signal to obtain the amplitude of the coherent integral of the lag branch; The discriminator in the delay-locked loop is used to calculate the signal propagation delay based on the amplitude of the coherent integral of the leading and lagging branches; A low-pass filter is used to remove noise from the signal propagation delay and obtain the filtered delay value. A numerically controlled oscillator for the reference signal is used to estimate the time delay experienced by the received signal based on the filtered time delay value; The estimation module estimates the receiver's position information based on the time delay experienced by the received signal.

7. A navigation receiver for CP-OFDM signals according to claim 6, characterized in that, The navigation receiver also includes a frequency-locked loop discriminator for stably tracking frequency deviations in the intermediate frequency signal.

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