A star flash SLE phase ranging method based on average excess delay and Rician K factor

Abstract

This invention belongs to the field of wireless ranging and positioning technology, specifically relating to a star-flash SLE phase ranging method based on average excess delay and the Rician K factor. The invention first constructs a bidirectional channel frequency response (CFR), maps it to a complex frequency domain sequence, and performs an IFFT to obtain the channel impulse response, constructing a power-delay distribution (PDP). Then, noise floor estimation and denoising are performed, followed by extraction of average excess delay, RMS delay spread, and Rician K factor estimates to form a joint discriminant index characterizing multipath and non-line-of-sight (NLS) levels. A dynamic peak value threshold is generated based on the joint discriminant index, the earliest valid path satisfying the dynamic threshold is selected, and the corresponding distance estimate is output. Compared with the traditional fixed-threshold complex-valued distance estimation (CDE) phase ranging method, this invention can suppress systematic deviations caused by misselection of strong reflection paths under strong multipath / NLS conditions, improving ranging accuracy and robustness, and is suitable for deployment on resource-constrained microcontroller platforms.

Description

Technical Field

[0001] This invention relates to the field of wireless ranging and positioning technology, specifically to a star-flash SLE phase ranging method based on average excess delay and Rician K factor. Background Technology

[0002] In recent years, wireless ranging and positioning technologies have been widely used in fields such as smart cars, smart terminals, smart homes, and smart manufacturing, leading to an increasing demand for high-precision ranging and positioning based on wireless signals. Wireless ranging (SLE) is a highly attractive ranging platform due to its low cost, low power consumption, and widespread deployment. However, traditional ranging methods based on received signal strength, Time of Flight (ToF) / Time of Arrival (ToA), and Angle of Arrival (AoA) suffer from limitations such as limited resolution, high hardware modification costs, or strong dependence on array antennas, making it difficult to achieve decimeter-level accuracy on ordinary SLE chips.

[0003] The core specification for StarScan introduces a phase ranging mechanism, which estimates propagation delay by measuring carrier phase at multiple frequency points and utilizing the linear variation of phase with frequency, thus achieving high range resolution ranging. Existing commonly used Complex-valued Distance Estimation (CDE) methods typically map the phase of multiple frequency points to a complex frequency domain sequence and then perform IFFT. In the time-domain amplitude sequence, a fixed threshold is used to search for the first peak exceeding the threshold as the direct path, thereby obtaining the distance estimate.

[0004] However, in complex real-world propagation environments, existing fixed-threshold-based phase ranging methods are susceptible to multipath reflections, non-line-of-sight obstructions, and channel fading. This can lead to situations where the peak value of the direct path is submerged or replaced by a strongly reflected path, resulting in increased distance estimation errors and decreased stability. Furthermore, the signal amplitude scale varies significantly across different scenarios, making it difficult for fixed thresholds to account for both false positives and false negatives, thus lacking robustness. Therefore, a star-flash SLE phase ranging method is needed that can adaptively adjust the peak value determination strategy based on changes in the propagation environment, thereby improving the accuracy and stability of ranging across multiple scenarios. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of phase distortion and peak misselection caused by multipath effects, non-line-of-sight propagation, and external interference in star-flash SLE phase ranging, and to overcome the resulting defects such as decreased ranging accuracy, poor stability, and insufficient robustness. To this end, this invention proposes a star-flash SLE phase ranging method based on average excess delay and the Rician K factor. By extracting delay statistical features and dominant path features at the CIR (Channel Impulse Response) / PDP (Power Delay Profile) level and generating a dynamic threshold, the earliest effective propagation path is adaptively selected, improving the ranging accuracy and stability in various scenarios such as indoor multipath propagation, in-vehicle NLOS, and outdoor line-of-sight (LOS). Simultaneously, the algorithm has low complexity and is suitable for deployment on microcontroller platforms.

[0006] The technical solution of the present invention is as follows: A star-flash SLE phase ranging method based on average excess time delay and Rician K factor includes the following steps: S1. Two-way phase measurement and synthesis of CFR (Channel Frequency Response) construction.

[0007] Phase measurements of the forward and reverse links are performed at multiple frequency points using the SLE channel sounding mechanism. The local oscillator offset and time offset between the transmitter and receiver are canceled by bidirectional phase synthesis to obtain a bidirectional phase sequence related to the propagation distance. A bidirectional synthesized channel frequency response sequence containing multipath components is then constructed.

[0008] S2. Construction of complex frequency domain sequences and acquisition of channel impulse response (CIR).

[0009] The bidirectional phase sequence is mapped to a complex frequency domain sequence, and an inverse fast Fourier transform (IFFT) at point B is performed to obtain the time-domain impulse response amplitude sequence, thereby obtaining the CIR.

[0010] S3. Construction of Power-Delay Distribution (PDP) and Extraction of Effective Path Set.

[0011] Based on the time-domain impulse response amplitude sequence obtained in step S2, a power-delay distribution (PDP) is constructed, noise floor estimation and denoising are performed, and an effective path index set is determined according to the power threshold for subsequent statistic and K-factor estimation.

[0012] S4. Extraction of average excess latency and RMS latency extension features.

[0013] The average excess delay and RMS delay spread are calculated within the effective path index set to characterize the center of gravity and dispersion of energy distribution, and to represent multipath tailing and non-line-of-sight tendency.

[0014] S5 and Rician K factor feature extraction.

[0015] The maximum power peak is determined in the denoised PDP and a peak protection window is constructed. The multipath background power is obtained by summing the effective path energies outside the peak protection window, and the Rician K factor is calculated to characterize the dominance of the main path.

[0016] S6. Dynamic threshold generation and adjustment based on linear weighting of joint features.

[0017] A joint discrimination index is constructed based on the average excess delay, RMS delay spread and Rician K factor, and a dynamic threshold for peak determination is generated accordingly. At the same time, the dynamic threshold is limited to a preset range so that the threshold can be adaptively adjusted according to the propagation environment.

[0018] S7. Peak value determination and distance estimation based on dynamic threshold.

[0019] In the time-domain impulse response amplitude sequence, a set of local peak indices is determined. A dynamic threshold determination rule with relative main peak normalization is adopted. The earliest effective propagation path index that meets the threshold condition is selected from the set of local peak indices, and the distance estimation result is output based on the index.

[0020] The main beneficial effects of this invention are as follows: (1) By using the average excess delay and RMS delay extension to characterize the centroid and diffusion degree of energy distribution, and combining the Rician K factor to characterize the dominance of the main path, the joint discrimination of multipath and non-line-of-sight degree is realized, thereby providing an adaptive basis for ranging strategy.

[0021] (2) Based on the joint discrimination index, a dynamic threshold is generated so that the peak determination sensitivity can be adaptively adjusted with environmental changes, thereby reducing the systematic ranging deviation caused by the fixed threshold misselection of strong reflection path under strong multipath conditions.

[0022] (3) Adopting a relative peak normalization determination method reduces the impact of amplitude absolute scale differences caused by changes in transmit power, distance, and fading on the threshold strategy, thereby improving stability under different signal-to-noise ratio conditions.

[0023] (4) The method relies only on the existing multi-frequency phase measurement and IFFT processing of SLE, without the need for additional hardware and array antennas, and has low complexity, making it suitable for deployment on resource-constrained microcontroller platforms. Attached Figure Description

[0024] Figure 1This is a flowchart of the low-power SLE phase ranging method of the present invention. Figure 2 This is a schematic diagram of the power-delay distribution under LOS conditions according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the power-delay distribution under NLOS conditions in an embodiment of the present invention; Figure 4 This is a schematic diagram of the channel impulse response under LOS conditions according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the channel impulse response under NLOS according to an embodiment of the present invention. Detailed Implementation

[0025] The following description illustrates specific embodiments of the present invention, and is not intended to limit the exemplary embodiments according to this application. To avoid confusion or obscuring the focus of the present invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] A starburst SLE phase ranging method based on average excess time delay and Rician K factor includes the following steps: (e.g.) Figure 1 ) S1, Two-way phase measurement and construction of synthesized CFR Assumption For SLE phase ranging process due to propagation distance The resulting delay This represents the time offset between the transmitting end I and the reflecting end R. This is the phase shift difference between the local oscillator (LO) signal at the transmitting end and the LO signal at the reflecting end. For the k-th channel, the phase measured at the reflecting end is: In the presence of multipath, the channel frequency response received at the reflecting end is: , in Indicates the reflecting end at the first The synthesized channel frequency response received at each frequency point Indicates the number of resolvable multipath components. Indicates the first reflector end Complex gain of multipath components, For the first The propagation delay of the multipath components relative to the reference time (where The time delay corresponding to the direct or earliest arrival path is the same as mentioned above. correspond), This represents the noise propagating from the transmitter to the receiver.

[0027] Similarly, the phase measured at the transmitting end is obtained as follows: Phase measured at the reflecting end compared to, and The algebraic signs in the two expressions are opposite, but their physical meanings and numerical magnitudes are the same. Because the transmitting end I and the reflecting end R play different roles in the measurement process, the superscript... and These are used to distinguish the physical quantities measured at the reflecting end and the transmitting end, respectively. In the case of multipath propagation, the response received at the transmitting end is... ,in Indicates the sending end's first The complex gain of the multipath component is given; the meanings of the other symbols are the same as before.

[0028] Will and After the phases measured at each point are added together, the signal travels twice the distance r between I and R. The time offset cancels out the LO offset, and the phase difference (i.e., the bidirectional phase sequence) is: The bidirectional CFR is obtained by calculating one signal frequency hopping (i.e., completing one round of scanning of all frequency hopping points): in, This is the equivalent interference term formed by the superposition of non-principal path multipath components and noise.

[0029] S2. Construction of complex frequency domain sequences and acquisition of channel impulse response (CIR) Based on the bidirectional phase sequence obtained in step S1, complex frequency domain mapping and B-point IFFT processing are performed. Assume that a single frequency hopping measurement yields... Each frequency point corresponds to a set of frequencies. The discrete bidirectional phase sequence is defined as: The frequency step size between adjacent frequency points is This frequency step size limits the maximum observable propagation delay of the system: Therefore, the maximum unambiguous ranging range can be obtained: in The speed of light. Discrete bidirectional phase sequences. Mapped to a complex frequency domain sequence and normalized. For the first The amplitude of bidirectional CFR at each frequency point is constructed as follows: For complex frequency domain sequences conduct Point-wise inverse fast Fourier transform, where By increasing the time-domain fence density through zero-padding, the time-domain impulse response (CIR) is obtained, with an amplitude of .

[0030] The corresponding distance mapping relationship is: in, For IFFT output sequence The delay sampling index corresponds to the discrete delay as: .

[0031] In the traditional CDE method, it is usually done by... The propagation distance is estimated by searching for the first peak exceeding a fixed threshold. However, under multipath or non-line-of-sight conditions, this peak may not correspond to a direct path, leading to increased ranging error. Further, a set of valid paths is extracted in step S3.

[0032] S3. Power-Delay Distribution Construction and Effective Path Set Extraction Based on the time-domain impulse response amplitude obtained in step S2, a power-delay distribution (PDP) is constructed, whose discrete form is defined as: The time delay sampling interval is The corresponding discrete delay is .

[0033] To suppress the influence of the noise floor and the low-power wake at the far end on the statistics, we first set a pre-defined noise estimation interval. Internal estimated noise floor power: in The tail region of the PDP sequence that has no multipath components is defined as... , As the starting index of the noise estimation interval, this embodiment takes... ,in This indicates the floor function. As a proportion of the noise estimation interval length, this embodiment takes , This represents the operation of finding the median of the elements in a set.

[0034] Construct the denoised power sequence: That is to Noise floor subtraction is performed when hour Otherwise, set it to zero.

[0035] The set of sampling points with denoising power higher than the power threshold is denoted as the effective path index set: in The normalized power threshold of the relative denoised peak power is defined as follows: , The threshold ratio coefficient (in this embodiment, it is taken as...) Noise estimation interval With valid path index set They do not intersect and each performs two independent functions: noise power estimation and effective path selection. Used for subsequent calculations of delay statistics and the Rician K-factor.

[0036] S4. Feature Extraction of Average Excess Latency and RMS Delay Spread Based on the denoised power sequence obtained in step S3 With valid path index set In the set Internal calculation of average excess latency It is defined as the power-weighted mean of time delay: To further characterize the energy dispersion along the time delay axis and enhance sensitivity to multipath tailing, the RMS delay spread is calculated simultaneously: in, Used to characterize the centroid of the channel energy distribution on the time delay axis Used to characterize the dispersion of energy distribution. When Larger and When the value increases, it indicates that the channel energy is spread to later arrival paths, multipath tail is significant, and the possibility of non-line-of-sight propagation is high; when Smaller and When the value is smaller, it indicates that energy is concentrated on the early arrival path, and the line-of-sight component is more likely to dominate.

[0037] S5 and Rician K-factor feature extraction In the power-time delay distribution, determine the index corresponding to the maximum power peak. The corresponding main diameter power is: in To The noise reduction power after noise floor subtraction (see the definition in step S3) is used to reduce the impact of the noise floor on the K-factor estimation.

[0038] To avoid miscalculating the main peak energy into the multipath background power, a main peak protection window is constructed: in This is the window half-width parameter. Its value is usually equal to the number of sampling points corresponding to the half-width of the main peak power, and is related to the IFFT output fence density. If the value is too small, the side lobes of the main peak will be mistakenly included in the multipath background; if it is too large, the nearby true multipath components will be lost. In this embodiment, the value is set to... .

[0039] Summing the power components other than the main peak protection window yields the multipath background power: Based on this, the Rician K factor is estimated as follows: in To prevent the denominator from being a tiny constant of zero, a larger K value indicates a higher proportion of energy from the main path (direct or dominant early arrival path); a smaller K value indicates that multipath background energy is dominant, and the propagation environment is more likely to exhibit non-line-of-sight characteristics.

[0040] S6. Dynamic threshold generation and adjustment based on linear weighting of joint features Based on the average excess delay obtained in step S4 With RMS latency extension and the Rician K factor obtained in step S5 Construct a joint discriminant index to characterize the multipath and non-line-of-sight propagation characteristics of a channel. Its definition is: in, and K is used to characterize the distribution and diffusion of channel energy on the time delay axis, while K is used to characterize the dominance of the main path energy relative to the multipath background. The maximum unambiguous propagation delay, determined by the frequency step size, is used to achieve feature dimension normalization, and its calculation formula is as follows: (See the definition in step S2). All weights are positive real numbers, used to balance the average excess delay term, RMS delay expansion term, and Rician K factor term against the joint discriminant index. The contribution of this embodiment is taken , , .

[0041] When joint discriminant indicators When the value increases, it indicates that the channel energy distribution extends to later arrival paths and the dominance of the main path decreases, increasing the likelihood of multipath or non-line-of-sight propagation; when When the value decreases, it indicates that the channel energy is concentrated on the early arrival path and the main path energy is dominant, making the line-of-sight propagation characteristics more pronounced.

[0042] Based on the rating Generate a dynamic threshold for CDE peak detection: in The baseline threshold corresponds to the reference score. The relative peak determination threshold is usually taken as the median value between 0.4 and 0.7. The control threshold is adjusted by the coefficient. The sensitivity to change is typically taken as 0.1 to 0.3; For reference scoring, the LOS calibration scenario can be used. value; and These are the allowed lower and upper bounds for the dynamic threshold, used to prevent the threshold from being too low or too high under extreme conditions. The dynamic threshold... Limited to a preset range within, that is In this embodiment, we take... , , , .

[0043] S7. Peak value determination and distance estimation based on dynamic threshold Based on the time-domain impulse response amplitude obtained in step S2 The dynamic threshold obtained in step S6 First, determine the set of local peak indices: in, , It indicates that...

[0044] In the local peak set In the middle, a dynamic threshold determination rule with relative main peak normalization is used to determine the index corresponding to the earliest propagation path that meets the conditions: The relative peak normalization determination method eliminates the sensitivity of the absolute value of the amplitude to changes in transmit power, channel fading and distance by using the global maximum peak value as a reference, so that the dynamic threshold has consistent discrimination significance under different signal-to-noise ratios and propagation distances.

[0045] According to the index Calculate the propagation distance: A simulation platform was built to simulate the method of this invention. The simulation was conducted in both LOS and NLOS scenarios. , The comparison results of key characteristic parameters such as the Rician K factor are shown in Table 1. It can be seen that their differences can reflect the influence of changes in propagation conditions on the discrimination index.

[0046] Table 1 Statistical results of key feature parameters in LOS / NLOS scenarios Distance measurement characteristics under LOS conditions, such as Figure 2 and Figure 4 : in Figure 2 For the comparison of PDP before and after denoising under LOS conditions, the principal path energy is concentrated in the early arrival path. Figure 2 The top sub-image shows the PDP before denoising, and the bottom sub-image shows the PDP after denoising. It can be seen that the multipath background is effectively suppressed after denoising, demonstrating the denoising processing proposed in this invention's ability to suppress low-power wakes. Figure 4 This is a CIR amplitude sequence under LOS conditions, with a significant main peak and The marker position almost coincides with the main peak, indicating the joint discriminant index of the present invention. It can accurately reflect the characteristics of concentrated line-of-sight energy and dominant main path, thereby generating a high dynamic threshold and accurately locking the main peak as the direct path.

[0047] Distance measurement characteristics under NLOS conditions, such as Figure 3 and Figure 5 : in Figure 3 This is a comparison of the PDP before and after denoising under NLOS conditions. Figure 3 The top sub-image shows the PDP before denoising, and the bottom sub-image shows the PDP after denoising. The multipath background energy is significant and widely distributed. Figure 5 For the CIR amplitude sequence under NLOS conditions, the maximum peak appears in a later time delay due to strong reflection interference. The marker position has been significantly shifted backward. Further rightward shift and crossing the multipath tail region indicate the joint discrimination index of the present invention. It can keenly identify the energy diffusion and main path weakening characteristics of NLOS, thereby reducing the dynamic threshold and allowing weak direct paths to enter the candidate peak set, avoiding the misselection of strong reflections as direct paths, demonstrating the robustness of this invention against multipath and NLOS interference.

[0048] The above description is merely a specific embodiment of the present invention. It should be noted that those skilled in the art should not consider the specific implementation of the present invention to be limited to these descriptions. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Those skilled in the art can make various changes in form and detail, including making some simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A star-flash SLE phase ranging method based on average excess time delay and Rician K factor, characterized in that, Includes the following steps: S1, Two-way phase measurement and construction of synthesized CFR; Phase measurements of the forward and reverse links are performed at multiple frequency points using the SLE channel sounding mechanism. The local oscillator offset and time offset between the transmitter and receiver are canceled by bidirectional phase synthesis to obtain a bidirectional phase sequence related to the propagation distance, and a bidirectional synthesized channel frequency response sequence containing multipath components is constructed. S2. Construction of complex frequency domain sequences and acquisition of channel impulse response (CIR); The bidirectional phase sequence is mapped to a complex frequency domain sequence, and an inverse fast Fourier transform (IFFT) at point B is performed to obtain the time-domain impulse response amplitude sequence, thereby obtaining the CIR. S3. Construction of Power-Delay Distribution PDP and Extraction of Effective Path Set; Based on the time-domain impulse response amplitude sequence obtained in step S2, a power-delay distribution (PDP) is constructed, noise floor estimation and denoising are performed, and an effective path index set is determined according to the power threshold for subsequent statistic and K-factor estimation. S4. Extraction of average excess latency and RMS latency extension features; The average excess delay and RMS delay spread are calculated within the effective path index set to characterize the center of gravity and dispersion of energy distribution, and to represent multipath tailing and non-line-of-sight tendency. S5 and Rician K-factor feature extraction; The maximum power peak is determined in the denoised PDP and a peak protection window is constructed. The multipath background power is obtained by summing the effective path energies outside the peak protection window and the Rician K factor is calculated to characterize the dominance of the main path. S6. Dynamic threshold generation and adjustment based on linear weighting of joint features; A joint discrimination index is constructed based on the average excess delay, RMS delay spread and Rician K factor, and a dynamic threshold for peak determination is generated accordingly. At the same time, the dynamic threshold is limited to a preset range so that the threshold can be adaptively adjusted according to the propagation environment. S7. Peak value determination and distance estimation based on dynamic threshold; In the time-domain impulse response amplitude sequence, a set of local peak indices is determined. A dynamic threshold determination rule with relative main peak normalization is adopted. The earliest effective propagation path index that meets the threshold condition is selected from the set of local peak indices, and the distance estimation result is output based on the index.

2. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 1, characterized in that, Step S1 specifically involves: Assumption For SLE phase ranging process due to propagation distance The resulting delay This represents the time offset between the transmitting end I and the reflecting end R; This is the phase shift difference between the local oscillator signal at the transmitting end and the LO signal at the reflecting end. For the k-th channel, the phase measured at the reflecting end is: In the presence of multipath, the channel frequency response received at the reflecting end is: ,in Indicates the reflecting end at the first The synthesized channel frequency response received at each frequency point Indicates the number of resolvable multipath components. Indicates the first reflector end Complex gain of multipath components, For the first The propagation delay of the multipath components relative to the reference time. This represents noise propagating from the transmitter to the receiver. The phase measured at the transmitting end is: In the case of multipath transmission, the response received at the sending end is ,in Indicates the sending end's first Complex gain of multipath components; Will and After adding the phases measured at each location, the phase difference is: The bidirectional CFR obtained by calculating the frequency hopping of a single signal is: in, This is the equivalent interference term formed by the superposition of non-principal path multipath components and noise.

3. The star-flash SLE phase ranging method based on average excess delay and Rician K factor as described in claim 1, characterized in that, Step S2 specifically involves: Based on the bidirectional phase sequence obtained in step S1, complex frequency domain mapping and B-point IFFT processing are performed. Let the total number of values ​​obtained in one frequency hopping measurement be... Each frequency point corresponds to a set of frequencies. The discrete bidirectional phase sequence is defined as: The frequency step size between adjacent frequency points is This frequency step size limits the maximum observable propagation delay of the system: Therefore, the maximum unambiguous ranging range can be obtained: in For the speed of light; discrete bidirectional phase sequence Mapped to a complex frequency domain sequence and normalized. For the first The amplitude of bidirectional CFR at each frequency point is constructed as follows: For complex frequency domain sequences conduct Point-wise inverse fast Fourier transform, where By increasing the time-domain fence density through zero-padding, a time-domain impulse response with an amplitude of [missing value] is obtained. ; The corresponding distance mapping relationship is: in, For IFFT output sequence The time delay sampling index corresponds to the discrete time delay as .

4. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 1, characterized in that, Step S3 specifically involves: Based on the time-domain impulse response amplitude obtained in step S2, a power-delay distribution (PDP) is constructed, whose discrete form is defined as: The time delay sampling interval is The corresponding discrete delay is ; Within the preset noise estimation range Internal estimated noise floor power ; Construct the denoised power sequence: That is to Noise floor subtraction is performed when hour Otherwise, set to zero; The set of sampling points with denoising power higher than the power threshold is denoted as the effective path index set: in The normalized power threshold of the relative denoised peak power is defined as follows: , Threshold scaling factor; noise estimation interval With valid path index set They do not intersect and each performs two independent functions: noise power estimation and effective path selection. Used for subsequent calculations of delay statistics and the Rician K factor.

5. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 4, characterized in that, Low Noise Power The calculation formula is as follows: in The tail region of the PDP sequence that has no multipath components is defined as... , This is the starting index for the noise estimation interval. ,in This indicates the floor function. The proportion of the noise estimation interval length. This represents the operation of finding the median of the elements in a set.

6. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 1, characterized in that, Step S4 specifically involves, Based on the denoised power sequence obtained in step S3 With valid path index set In the set Internal calculation of average excess latency It is defined as the power-weighted mean of time delay: Calculate RMS latency spread: in, Used to characterize the centroid of the channel energy distribution on the time delay axis Used to characterize the dispersion of energy distribution. When Larger and When the value increases, it indicates that the channel energy is spread to later arrival paths, multipath tail is significant, and the possibility of non-line-of-sight propagation is high; when Smaller and When the value is smaller, it indicates that energy is concentrated on the early arrival path, and the line-of-sight component is more likely to dominate.

7. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 1, characterized in that, Step S5 specifically involves: In the power-time delay distribution, determine the index corresponding to the maximum power peak. The corresponding main diameter power is: in To Noise reduction power after noise floor subtraction; To avoid miscalculating the main peak energy into the multipath background power, a main peak protection window is constructed: in This is the window half-width parameter; Summing the power components other than the main peak protection window yields the multipath background power: Based on this, the Rician K factor is estimated as follows: in To prevent tiny constants with a denominator of zero.

8. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 1, characterized in that, Step S6 specifically involves: Based on the average excess delay obtained in step S4 With RMS latency extension And the Rician K factor obtained in step S5 Construct a joint discriminant index to characterize the multipath and non-line-of-sight propagation characteristics of a channel. Its definition is: in, and K is used to characterize the distribution and diffusion of channel energy on the time delay axis, while K is used to characterize the dominance of the main path energy relative to the multipath background. The maximum unambiguous propagation delay, determined by the frequency step size, is used to achieve feature dimension normalization, and its calculation formula is as follows: ; All weights are positive real numbers, used to balance the average excess delay term, RMS delay expansion term, and Rician K factor term against the joint discriminant index. Contributions; Based on the rating Generate a dynamic threshold for CDE peak detection: in The baseline threshold corresponds to the reference score. The relative peak determination threshold at the location; The control threshold is adjusted by the coefficient. Sensitivity to change; For reference scoring, the LOS calibration scenario is used. value; and These are the allowed lower and upper bounds for the dynamic threshold. The dynamic threshold Limited to a preset range within, that is .

9. The star-flash SLE phase ranging method based on average excess delay and Rician K factor according to claim 1, characterized in that, Step S7 specifically involves, Based on the time-domain impulse response amplitude obtained in step S2 The dynamic threshold obtained in step S6 First, determine the set of local peak indices: in, , Indicates and; In the local peak set In the middle, a dynamic threshold determination rule with relative main peak normalization is used to determine the index corresponding to the earliest propagation path that meets the conditions: According to the index Calculate the propagation distance: 。

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