LoRa modulation-based frequency offset estimation method and device, medium, and frequency offset estimation apparatus

Abstract

The application discloses a frequency offset estimation method and device based on LoRa modulation, a medium, and a frequency offset estimation device. The method comprises the following steps: estimating a decimal multiple frequency offset based on an upper chirp signal in a received chirp signal, and compensating the received chirp signal based on the decimal multiple frequency offset to obtain a compensated chirp signal; determining a first upper chirp signal and a first lower chirp signal from the compensated chirp signal, and the decimal multiple frequency offset is obtained based on the upper chirp signal in the chirp signal; determining a first position with the largest correlation peak of the first upper chirp signal and a reference upper chirp signal, and a second position with the largest correlation peak of the first lower chirp signal and a reference lower chirp signal; and estimating a target frequency offset based on the first position, the second position, and the decimal multiple frequency offset. The method can improve the accuracy of frequency offset estimation, reduce the influence of timing deviation on the accuracy of frequency offset estimation, improve the accuracy and precision of timing synchronization, and further improve the demodulation performance of a LoRa received signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of frequency offset estimation, and particularly relates to a frequency offset estimation method and device based on LoRa modulation, a medium and a frequency offset estimation device. BACKGROUND

[0002] LoRa (Long Range Radio) technology is one of the main technologies of LPWAN (Low Power Wide Area Network), and has advantages such as long distance, anti-interference, low power consumption, large capacity, flexible deployment, lightweight, low cost, and anti-frequency offset, and is widely used in the market. Meanwhile, LoRa is also a modulation method, which uses a CSS (Chirp Spread Spectrum) based method for communication.

[0003] However, due to the fact that the clock of the transceiver end of the communication system cannot be kept completely consistent, CFO (Carrier Frequency Offset) will be introduced in the received signal, and then the demodulation of the receiver system will be affected. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, a first object of the present application is to provide a frequency offset estimation method based on LoRa modulation, which can improve the accuracy of frequency offset estimation, reduce the influence of timing deviation on the accuracy of frequency offset estimation, improve the accuracy and precision of timing synchronization, and thus improve the demodulation performance of LoRa received signals.

[0005] A second object of the present application is to provide a frequency offset estimation device based on LoRa modulation.

[0006] A third object of the present application is to provide a computer readable storage medium.

[0007] A fourth object of the present application is to provide a frequency offset estimation device.

[0008] To achieve the above object, the first aspect of the present application provides a frequency offset estimation method based on LoRa modulation, which comprises: estimating a fractional multiple frequency offset based on an upper chirp signal in a received chirp signal, and compensating the received chirp signal based on the fractional multiple frequency offset to obtain a compensated chirp signal; determining a first upper chirp signal and a first lower chirp signal from the compensated chirp signal; determining a first position of a maximum correlation peak of the first upper chirp signal and a reference upper chirp signal, and a second position of a maximum correlation peak of the first lower chirp signal and a reference lower chirp signal; and estimating a target frequency offset based on the first position, the second position and the fractional multiple frequency offset, wherein the target frequency offset is positively correlated with the fractional multiple frequency offset.

[0009] To achieve the above object, the second aspect of the present application provides a frequency offset estimation device based on LoRa modulation, which comprises: a compensation module configured to estimate a fractional multiple frequency offset based on an upper chirp signal in a received chirp signal, and compensate the received chirp signal based on the fractional multiple frequency offset to obtain a compensated chirp signal; a first determination module configured to determine a first upper chirp signal and a first lower chirp signal from the compensated chirp signal; a second determination module configured to determine a first position of a maximum correlation peak of the first upper chirp signal and a reference upper chirp signal, and a second position of a maximum correlation peak of the first lower chirp signal and a reference lower chirp signal; and an estimation module configured to estimate a target frequency offset based on the first position, the second position and the fractional multiple frequency offset, wherein the target frequency offset is positively correlated with the fractional multiple frequency offset.

[0010] To achieve the above object, the third aspect of the present application provides a computer readable storage medium having a frequency offset estimation program based on LoRa modulation stored thereon, wherein the frequency offset estimation program based on LoRa modulation, when executed by a processor, implements the frequency offset estimation method based on LoRa modulation.

[0011] To achieve the above object, the fourth aspect of the present application provides a frequency offset estimation device, comprising a memory, a processor and a frequency offset estimation program based on LoRa modulation stored in the memory and executable on the processor, wherein the processor, when executing the frequency offset estimation program based on LoRa modulation, implements the frequency offset estimation method based on LoRa modulation.

[0012] The frequency offset estimation method, device and medium based on LoRa modulation and the frequency offset estimation equipment of the embodiment of the application can improve the accuracy of frequency offset estimation, reduce the influence of timing deviation on the accuracy of frequency offset estimation, improve the accuracy and precision of timing synchronization, and further improve the demodulation performance of LoRa received signals.

[0013] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a flowchart of a frequency offset estimation method based on LoRa modulation according to an embodiment of the application;

[0015] Figure 2 is a flowchart of estimating a target frequency offset based on the first position, the second position and the fractional multiple frequency offset according to an embodiment of the application;

[0016] Figure 3 is a structural diagram of a frequency offset estimation device based on LoRa modulation according to an embodiment of the application. DETAILED DESCRIPTION

[0017] The embodiments of the application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application.

[0018] The embodiments of the application are described below with reference to the accompanying drawings. Figures 1-3 The frequency offset estimation method, device and medium based on LoRa modulation and the frequency offset estimation equipment according to the embodiments of the application are described.

[0019] Figure 1 is a flowchart of a frequency offset estimation method based on LoRa modulation according to an embodiment of the application;

[0020] Since LoRa technology is a communication method based on Chirp spread spectrum, the generation method of Chirp signals is mostly used in the generation process of LoRa signals.

[0021] For linear chirps (where the frequency *s* of each chirp varies linearly with time *t*), a chirp whose frequency increases linearly with time is called an up-chirp, and conversely, a chirp whose frequency decreases linearly with time is called a down-chirp. The mathematical expression for a chirp signal can be:

[0022]

[0023] Its instantaneous frequency can be expressed by the following formula:

[0024]

[0025] Among them, f c The center frequency of the carrier wave is represented by BW; the bandwidth of the signal is represented by μ; the rate of change of frequency is represented by μ: when the chirp is up-chirp, μ = 1, and the instantaneous frequency continuously increases; when the chirp is down-chirp, μ = -1, and the instantaneous frequency continuously decreases; k / T s Denotes the initial frequency, k∈[0, 2]. SF -1];T s T represents the duration of the Chirp signal. fold =T s -k / BW. Since phase is an integral of the frequency function, the mathematical expression for the resulting CSS modulated signal can be expressed as:

[0026]

[0027] in, The initial phase is 0, and the phases of the two function segments are continuous.

[0028] For LoRa received signals, the digital signal sampling rate f s =BW, signal period Where SF (Spread Factor) is the digital baseband expression for the LoRa received signal.

[0029]

[0030] Demodulation of LoRa received signals: The LoRa received signal can be correlated with the local Up-Chirp or Down-Chirp signal to obtain a single-frequency sine wave signal, and the signal frequency is the modulation signal information.

[0031]

[0032] If there is timing deviation (TA) and carrier frequency deviation (f) in the LoRa received signal cfo), the received baseband signal becomes:

[0033]

[0034] After correlation operation with the local signal, the result is:

[0035]

[0036] From the above formula, the component of timing deviation and the component of carrier frequency offset will simultaneously affect the signal frequency point position, causing demodulation error, and the component of timing deviation and the component of carrier frequency offset can be converted to each other, if there is no effective way to distinguish the two, the component of carrier frequency offset may cause abnormal timing synchronization, causing signal symbol segmentation error, affecting demodulation performance. That is, the system using CSS communication, CFO may affect the final demodulation result, LoRa as a system based on CSS communication, needs to estimate and correct the CFO at the receiving end.

[0037] It is difficult to completely separate the influence of one factor on frequency offset from the other factor by single timing deviation estimation and carrier frequency offset estimation. A combined synchronization frequency offset estimation method is proposed in the related art, which uses the Up-chirp and Down-Chirp signals in the LoRa preamble sequence to solve the equation set demodulation. But the scheme assumes that the timing deviation and the carrier frequency offset are both integer multiples of the sampling rate, but in actual situation, it is basically impossible to meet this condition, and the fractional carrier frequency offset and timing deviation will cause the peak value of the correlated signal to decrease, which may cause the peak value to be misaligned under low signal-to-noise ratio, causing abnormal timing estimation and frequency offset estimation, affecting demodulation.

[0038] Therefore, the present application proposes a frequency offset estimation method based on LoRa modulation, which uses the Up-chirp and Down-Chirp signals in the LoRa preamble sequence to jointly estimate the frequency offset, and can obtain accurate frequency offset estimation results. Generally, the LoRa system still has good demodulation performance when the carrier frequency offset value is less than 1 / 4 of the communication bandwidth, so the present scheme assumes that the frequency offset value is less than As shown in Figure 1 The frequency offset estimation method based on LoRa modulation comprises:

[0039] S101, estimate the fractional frequency offset based on the Up-chirp signal in the received chirp signal, and compensate the received chirp signal based on the fractional frequency offset to obtain a compensated chirp signal.

[0040] Specifically, the estimating the fractional frequency offset based on the up-chirp signal in the received chirp signal can include: obtaining a continuous second up-chirp signal and a third up-chirp signal from the up-chirp signal in the received chirp signal, the second up-chirp signal and the third up-chirp signal both having a length of a symbol period; and estimating the fractional frequency offset based on the second up-chirp signal and the third up-chirp signal.

[0041] Specifically, from the LoRa preamble sequence in the received chirp signal, two non-timed up-chirp signals Up-chirp both having a length of a symbol period, i.e., a second up-chirp signal and a third up-chirp signal, are obtained, and the fractional carrier frequency offset is estimated using the second up-chirp signal and the third up-chirp signal:

[0042]

[0043] where ω FPO is the fractional frequency offset, SF is a spreading factor, is an expression of the second up-chirp signal, is an expression of the third up-chirp signal, n is a sampling number, arg is a phase angle operation, and conj is a complex conjugate operation.

[0044] After obtaining the fractional frequency offset, the received chirp signal is compensated by the following formula to obtain a compensated chirp signal:

[0045] where x 1 (n) is the compensated chirp signal, x 0 (n) is the received chirp signal, and j is an imaginary unit. Thus, the received chirp signal is corrected for the fractional frequency offset according to the fractional frequency offset.

[0046] S102, determining a first up-chirp signal and a first down-chirp signal from the compensated chirp signal, the fractional frequency offset being estimated based on the up-chirp signal in the chirp signal.

[0047] Specifically, the first up-chirp signal 0 and the first down-chirp signal both having a length of a symbol period are determined from the compensated chirp signal x (n). That is, the first up-chirp signal and the first down-chirp signal in a symbol period are complete up-chirp and down-chirp signals. It should be noted that the interval between the first up-chirp signal and the first down-chirp signal is an integer number of symbol periods.

[0048] S103, respectively determine a first position of a maximum correlation peak of the first up-chirp signal and the reference up-chirp signal, and a second position of a maximum correlation peak of the first down-chirp signal and the reference down-chirp signal.

[0049] Specifically, the first up-chirp signal and the reference up-chirp signal are correlated, and after performing FFT (Fast Fourier Transform) on the correlation result, the modulus of the FFT result is obtained through the abs (absolute value) function, and finally the first position K Up of the maximum correlation peak is obtained through the maxIndex (maximum value index) function. The first down-chirp signal and the reference down-chirp signal are correlated, and after performing FFT (Fast Fourier Transform) on the correlation result, the modulus of the FFT result is obtained through the abs function, and finally the second position K Down of the maximum correlation peak is obtained through the maxIndex function.

[0050]

[0051] S104, estimating the target frequency offset based on the first position, the second position and the fractional frequency offset, the target frequency offset being positively correlated with the fractional frequency offset.

[0052] As an example, see Figure 2 , estimating the target frequency offset based on the first position, the second position and the fractional frequency offset can include steps S201-S202:

[0053] S201, determining a target peak shift value caused by an integer multiple frequency offset based on the first position and the second position.

[0054] Specifically, step S201 can include: determining an initial peak shift value based on the mean of the first position and the second position; determining the target peak shift value based on the initial peak shift value, a first preset value and a second preset value.

[0055] In this example, determining the target peak shift value based on the initial peak shift value, the first preset value and the second preset value can include: if the initial peak shift value is greater than the first preset value, determining the target peak shift value based on the difference between the initial peak shift value and the second preset value; if the initial peak shift value is less than the first preset value, determining the target peak shift value based on the sum of the initial peak shift value and the second preset value; wherein the first preset value is less than the second preset value, the first preset value is and the second preset value is SF is a spread factor. It should be noted that the initial peak shift value is a peak shift value corresponding to an initial integer multiple frequency offset.

[0056] Specifically, the initial peak shift value is determined based on the mean of the first position and the second position, that is, The initial peak shift value is determined, wherein I' CFO_IFO is the initial peak shift value, K Up is the first position, K Down is the second position. Further, if the initial peak shift value is the target peak shift value. If the initial peak shift value is the target peak shift value. Therefore, the target peak shift value is adjusted in the interval by the initial peak shift value, the first preset value and the second preset value.

[0057] S202, estimating a target frequency offset based on the target peak shift value and the decimal multiple frequency offset, the target frequency offset being positively correlated with the target peak shift value.

[0058] Wherein, the target frequency offset ω CFO satisfies:

[0059] I CFO_IFO is the target peak shift value, ω FFO is the decimal multiple frequency offset, and SF is a spread factor.

[0060] Specifically, according to the target frequency offset ω CFO a correction sequence is generated, which can correct the received LoRa signal. The actual value of the frequency offset f can also be determined by the formula CFO , wherein f s is the sampling rate of the received chirp signal.

[0061] It should be noted that when the LoRa modulation-based frequency offset estimation method of the embodiment of the present application is simulated and verified, the error of the frequency offset estimation is still less than 1‰ under the ±50ppm frequency offset.

[0062] In summary, the frequency offset estimation method based on LoRa modulation in the embodiment of the present application can compensate the received chirp signal based on the fractional multiple frequency offset, obtain the compensated chirp signal, and determine the first upper chirp signal and the first lower chirp signal from the compensated chirp signal. The fractional multiple frequency offset is obtained based on the estimation of the upper chirp signal in the chirp signal. Then, the first position of the correlation peak maximum of the first upper chirp signal and the reference upper chirp signal, and the second position of the correlation peak maximum of the first lower chirp signal and the reference lower chirp signal are determined respectively. Finally, the target frequency offset is estimated based on the first position, the second position and the fractional multiple frequency offset. The LoRa received signal (i.e. the received chirp signal) containing the fractional multiple timing offset and the fractional multiple carrier frequency offset can be accurately estimated, and the influence of the timing offset on the frequency offset estimation accuracy is reduced. Then, the correction sequence is generated according to the target frequency offset, the received LoRa signal can be corrected, and the timing synchronization is performed using the corrected sequence, which can improve the accuracy and accuracy of the timing synchronization, and further improve the LoRa received signal demodulation performance.

[0063] Figure 3 is a structural schematic diagram of the frequency offset estimation device based on LoRa modulation in an embodiment of the present application. As shown in Figure 3 , the frequency offset estimation device based on LoRa modulation 100 comprises a compensation module 10, a first determination module 20, a second determination module 30 and an estimation module 40.

[0064] The compensation module 10 is configured to estimate the fractional multiple frequency offset based on the upper chirp signal in the received chirp signal, and compensate the received chirp signal based on the fractional multiple frequency offset to obtain the compensated chirp signal. The first determination module 20 is configured to determine the first upper chirp signal and the first lower chirp signal from the compensated chirp signal. The fractional multiple frequency offset is obtained based on the estimation of the upper chirp signal in the chirp signal. The second determination module 30 is configured to determine the first position of the correlation peak maximum of the first upper chirp signal and the reference upper chirp signal, and the second position of the correlation peak maximum of the first lower chirp signal and the reference lower chirp signal respectively. The estimation module 40 is configured to estimate the target frequency offset based on the first position, the second position and the fractional multiple frequency offset. The target frequency offset is positively correlated with the fractional multiple frequency offset.

[0065] It should be noted that other specific embodiments of the frequency offset estimation device based on LoRa modulation in the present application can refer to the frequency offset estimation method based on LoRa modulation described above.

[0066] In summary, the frequency offset estimation device based on LoRa modulation according to the embodiment of the application can compensate the received chirp signal based on the fractional multiple frequency offset, obtain the compensated chirp signal, and determine the first upper chirp signal and the first lower chirp signal from the compensated chirp signal. The fractional multiple frequency offset is obtained based on the upper chirp signal in the chirp signal. Then, the first position of the maximum correlation peak of the first upper chirp signal and the reference upper chirp signal, and the second position of the maximum correlation peak of the first lower chirp signal and the reference lower chirp signal are determined respectively. Finally, the target frequency offset is estimated based on the first position, the second position and the fractional multiple frequency offset. The LoRa received signal (i.e. the received chirp signal) containing the fractional multiple timing offset and the fractional multiple carrier frequency offset can be accurately estimated, the influence of the timing offset on the frequency offset estimation accuracy is reduced, the accuracy and precision of the timing synchronization are improved, and the demodulation performance of the LoRa received signal is improved.

[0067] The application further provides a computer readable storage medium having a frequency offset estimation program based on LoRa modulation stored thereon. When the frequency offset estimation program based on LoRa modulation is executed by a processor, the frequency offset estimation method based on LoRa modulation described above is implemented.

[0068] The computer readable storage medium according to the embodiment of the application, when the frequency offset estimation program based on LoRa modulation stored thereon is executed, can improve the accuracy of the frequency offset estimation, reduce the influence of the timing offset on the frequency offset estimation accuracy, improve the accuracy and precision of the timing synchronization, and further improve the demodulation performance of the LoRa received signal.

[0069] The application further provides a frequency offset estimation device comprising a memory, a processor, and a frequency offset estimation program based on LoRa modulation stored on the memory and executable on the processor. When the frequency offset estimation program based on LoRa modulation is executed by the processor, the frequency offset estimation method based on LoRa modulation described above is implemented.

[0070] The frequency offset estimation device according to the embodiment of the application, when the frequency offset estimation program based on LoRa modulation stored on the memory thereof is executed by the processor, can improve the accuracy of the frequency offset estimation, reduce the influence of the timing offset on the frequency offset estimation accuracy, improve the accuracy and precision of the timing synchronization, and further improve the demodulation performance of the LoRa received signal.

[0071] It is to be appreciated that the above description and the examples that follow are intended to be illustrative only and that changes can be made to the description, either functionally or chronologically, as well as changes being made concerning which elements of the description and / or examples are employed per se, all without departing from the spirit and scope of the application. It should be further appreciated that the logic and / or steps described in the flow diagrams and / or otherwise described herein can be considered as a sequence of executable instructions or a computer program product that can be executed by a computer, such as a computer-based system, processor, or other system that can fetch instructions from a instruction execution system, apparatus or device and execute the instructions. In this regard, the "computer-readable medium" can be any medium that can contain, store, communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus or device. The computer readable medium can comprise any one of the following: an electronic connection having one or more wires (electronic devices), a portable computer diskette (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CDROM). Further, the computer readable medium can even be paper or other suitable medium upon which the program is printed, as the program can be electronically captured, via, for example, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and stored in a computer memory.

[0072] It should be understood that aspects of the application can be implemented in hardware, software, firmware or combinations thereof. In the above embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any of the following techniques, which are known in the art and practice of the present application, can be used: a combination of logic gates, discrete logic, application specific integrated circuits (ASICs), programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), and / or other implementations to perform the logical functions of the blocks.

[0073] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] In the description of the application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0075] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0076] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0077] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0078] Although the embodiments of the application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be understood as a limitation on the application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the application.

Claims

1. A frequency offset estimation method based on LoRa modulation, characterized in that, The method comprises: estimating a fractional frequency offset based on an up-chirp signal in the received chirp signal, and compensating the received chirp signal based on the fractional frequency offset to obtain a compensated chirp signal; determining a first up-chirp signal and a first down-chirp signal from the compensated chirp signal; determining a first position of a correlation peak maximum of the first up-chirp signal and a reference up-chirp signal, and a second position of a correlation peak maximum of the first down-chirp signal and a reference down-chirp signal respectively; determining a target peak shift value caused by an integer frequency offset based on the first position and the second position; estimating a target frequency offset based on the target peak shift value and the fractional frequency offset, the target frequency offset being positively correlated with the target peak shift value and positively correlated with the fractional frequency offset.

2. The method of LoRa modulation based frequency offset estimation according to claim 1, wherein, The target frequency offset Satisfies: ， Wherein, the is the target peak shift value, the is the fractional frequency offset, and SF is the spreading factor.

3. The method of LoRa modulation based frequency offset estimation according to claim 1, wherein, The method comprises: determining an initial peak shift value based on a mean value of the first position and the second position; determining the target peak shift value based on the initial peak shift value, a first preset value and a second preset value.

4. The method of LoRa modulation based frequency offset estimation according to claim 3, wherein, The method comprises: if the initial peak shift value is greater than the first preset value, determining the target peak shift value based on a difference between the initial peak shift value and the second preset value; if the initial peak shift value is less than the first preset value, determining the target peak shift value based on a sum of the initial peak shift value and the second preset value; wherein the first preset value is less than the second preset value.

5. The method of frequency offset estimation based on LoRa modulation according to claim 4, characterized in that, The first preset value is , the second preset value is , and SF is a spreading factor.

6. The frequency offset estimation method based on LoRa modulation according to any one of claims 1 to 5, characterized in that, The method comprises: obtaining a second up-chirp signal and a third up-chirp signal from the up-chirp signal in the received chirp signal, the second up-chirp signal and the third up-chirp signal each having a length of a symbol period; estimating the fractional frequency offset based on the second up-chirp signal and the third up-chirp signal.

7. The frequency offset estimation method based on LoRa modulation according to any one of claims 1 to 5, characterized in that, The first up-chirp signal and the first down-chirp signal each have a length of a symbol period, and an interval between the first up-chirp signal and the first down-chirp signal is an integer number of symbol periods.

8. A frequency offset estimation apparatus based on LoRa modulation, characterized in that, The apparatus comprises: a compensation module configured to estimate a fractional frequency offset based on an up-chirp signal in the received chirp signal, and compensate the received chirp signal based on the fractional frequency offset to obtain a compensated chirp signal; a first determination module configured to determine a first up-chirp signal and a first down-chirp signal from the compensated chirp signal; a second determination module configured to determine a first position of a correlation peak maximum of the first up-chirp signal and a reference up-chirp signal, and a second position of a correlation peak maximum of the first down-chirp signal and a reference down-chirp signal respectively; an estimation module configured to determine a target peak shift value caused by an integer frequency offset based on the first position and the second position, and estimate a target frequency offset based on the target peak shift value and the fractional frequency offset, the target frequency offset being positively correlated with the target peak shift value and positively correlated with the fractional frequency offset.

9. A computer-readable storage medium, characterized in that, A computer readable storage medium having stored thereon a LoRa modulation based frequency offset estimation program, which when executed by a processor implements the LoRa modulation based frequency offset estimation method according to any one of claims 1 to 7.

10. A frequency offset estimation device, characterized in that, A computer readable storage medium having stored thereon a LoRa modulation based frequency offset estimation program, which when executed by a processor implements the LoRa modulation based frequency offset estimation method according to any one of claims 1 to 7.

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