CN116582815B - LOS and NLOS scene judging method based on ranging channel evaluation - Google Patents

LOS and NLOS scene judging method based on ranging channel evaluation Download PDF

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CN116582815B
CN116582815B CN202310571860.XA CN202310571860A CN116582815B CN 116582815 B CN116582815 B CN 116582815B CN 202310571860 A CN202310571860 A CN 202310571860A CN 116582815 B CN116582815 B CN 116582815B
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CN116582815A (en
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黄先日
杨旭磊
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Qingdao Chrystar Electronic Technology Co ltd
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    • H04W—WIRELESS COMMUNICATION NETWORKS
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    • H04W4/02—Services making use of location information
    • H04W4/023—Services making use of location information using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
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Abstract

The invention discloses a LOS and NLOS scene judging method based on ranging channel evaluation, which comprises the following steps: 1. calculating a predicted distance value measured next time; 2. calculating a predicted initial diameter reference energy value P based on the current measurement ref The method comprises the steps of carrying out a first treatment on the surface of the 3. Analyzing signals received by the DS-TWR base station to obtain related information values; 4. the related information value obtained in the step 3 is utilized to predict the initial diameter reference energy value P based on the last measurement lastref A predicted distance value P of the current measurement calculated based on the last positioning feedback ranging result lastpre Evaluating the current ranging channel quality, and dividing the channel level of the current ranging channel quality; 5. and (3) outputting whether the current ranging scene is LOS or NLOS by evaluating the data in the LOS and NLOS evaluation windows. The LOS and NLOS scene judging method based on the ranging channel evaluation with the structure can accurately judge whether the current ranging environment is an LOS scene or an NLOS scene in real time, effectively avoid the wrong ranging result from participating in positioning calculation, and improve the indoor positioning accuracy.

Description

LOS and NLOS scene judging method based on ranging channel evaluation
Technical Field
The invention relates to the technical field of LOS and NLOS scene judgment, in particular to a LOS and NLOS scene judgment method based on ranging channel evaluation.
Background
At present, an outdoor positioning technology based on GNSS is relatively mature, but in the indoor, satellite signals are easily shielded, normal positioning service cannot be completed, and positioning accuracy cannot meet service requirements. In recent years, the demand for high-precision positioning services is increasing, and 70% -80% of activities of people are counted to occur indoors, so that the indoor positioning technology is of great significance. Based on various requirements, many corresponding positioning technologies have been developed and achieve good results, such as infrared, radio frequency identification, ultrasound, WIFI, bluetooth, zigbee, visual positioning, and the like. However, the positioning system has the defects of low positioning precision or severe requirements on environment, and cannot meet the requirements of people on high precision and good environment self-adaption of an indoor positioning sensing system. The Ultra-wide band (UWB) positioning technology has the advantages of high interference resistance, extremely wide Bandwidth, high transmission rate, low power consumption and the like compared with other wireless positioning technologies.
UWB positioning technology relies on the accuracy of detection of the first path, which is generally relatively easy in Line of Sight (LOS) propagation environments, and enables relatively high positioning accuracy to be obtained. However, in some complex environments (e.g., indoor, underground environments), UWB signal propagation may randomly switch between two forms of LOS propagation and non-line-of-sight (Non Line of Sight, NLOS) propagation due to the effects of terrain complexity and obstacle-concentration. In the NLOS propagation mode, due to the lack of a direct signal path, the propagation time of the signal is prolonged, and a positive deviation is generated, which greatly influences the positioning accuracy. Therefore, LOS and NLOS scenes can be accurately identified in real time, erroneous ranging results can be effectively prevented from being involved in positioning calculation, and great help is provided for improving positioning accuracy.
Disclosure of Invention
The invention aims to provide an LOS and NLOS scene judging method based on ranging channel evaluation, which is used for accurately judging whether the current ranging environment is an LOS scene or an NLOS scene in real time, so that an erroneous ranging result is effectively prevented from participating in positioning calculation, and the indoor positioning accuracy is improved.
In order to achieve the above purpose, the present invention provides the following technical solutions:
an LOS and NLOS scene judging method based on ranging channel evaluation comprises the following steps:
step 1, calculating a predicted distance value of next measurement based on a current positioning feedback ranging result, wherein the specific method comprises the following steps:
1) Firstly, updating the last speed updating result to obtain the current speed updating result, wherein the method comprises the following steps:
v cur ＝ω last *v last +(1-ω last )*(d cur -d last )
wherein v is cur To update the result, ω, for the current speed last For the weight value corresponding to the predicted distance value measured last time, v last D, for last speed update result cur Feedback ranging result for current positioning, d last Feeding back a ranging result for the last positioning;
2) Then, feeding back the ranging result d according to the current positioning cur Update the result v with the current speed cur Calculating the predicted distance value d of the next measurement pre ：
d pre ＝d cur +v cur
Step 2, according to the current measured initial path energy value and noise energy P noi Calculating a predicted first-path reference energy value P based on the current measurement ref The specific method comprises the following steps:
1) Using a currently measured predicted distance value d calculated based on the last positioning feedback ranging result lastpre And a threshold d allowing fluctuation of the ranging result measth Summing to obtain the maximum reasonable distance measurement value d vld ＝d lastpre +d measth ；
2) Then by the actually measured ranging result d meas And the maximum reasonable distance measurement value d vld Comparing, if d meas >d vld The detection result shows that the distance measurement is unreasonable, and the energy of the head path is lower than the head path detection threshold value P detth The true head-path is not detected, and the current measurement based predicted head-path reference energy value P ref ＝P detth First diameter detection threshold P detth ＝P noi +15dB；
3) If d meas ≤d vld The ranging is reasonable, and the consistency of the energy of the first path detected twice needs to be judged:
first, the first path energy difference of the two detections is calculated:
ΔP FP ＝abs(P FP1 -P FP2 )
wherein DeltaP FP For the two-sided two-way ranging (DS-TWR) base station, the energy difference of the first path and the second path received by the base station, P FP1 For DS-TWR base station to receive signal energy of first path, P FP2 For the second time of receiving the signal energy of the first path of the DS-TWR base station, abs () is taken as absolute value operation;
then, the first path energy difference DeltaP is detected by two times FP And the first path energy difference threshold P FPth Comparing to determine whether the energy difference of the first path detected twice is reasonable:
when the energy difference delta P of the first path is detected twice FP Greater than the first path energy difference threshold P FPth The predicted first-path reference energy value based on the current measurement is P ref ＝min(P FP1 ,P FP2 ) Wherein, min () is the minimum value operation;
when the energy difference delta P of the first path is detected twice FP Less than or equal to the first path energy difference threshold P FPth The predicted first-path reference energy value based on the current measurement is P ref ＝max(P FP1 ,P FP2 ) Wherein, max () is the maximum value operation;
step 3, analyzing the signal received by the DS-TWR base station to obtain the following related information values: received signal energy P Rx Maximum path signal energy P max First path signal energy P FP Noise energy P noi Distance measurement result d of actual measurement meas 、SNR FP 、ΔP FP-ref 、ΔP FP-max 、ΔP FP-Rx And Δd meas-pre ；
Step 4, using the related information value obtained in step 3 to predict the initial diameter reference energy value P based on the last measurement lastref A predicted distance value P of the current measurement calculated based on the last positioning feedback ranging result lastpre Current ranging channel qualityThe line evaluation is used for dividing the channel level of the current ranging channel quality, and the specific method is as follows:
1): the energy difference delta P of the first path of the two detection FP From the first path energy difference threshold Δp FPth Judging whether the energy of the primary diameters detected twice is consistent;
when DeltaP FP >ΔP FPth The first paths of the two receiving detection are inconsistent, and the output ranging channel quality is evaluated as level=0;
when DeltaP FP ≤ΔP FPth The first diameters of the two receiving detection are identical, and then the next step of comparison judgment is carried out;
2): determining the first path signal energy P FP And the predicted initial diameter reference energy value P based on the last measurement lastref Is the difference DeltaP of (1) FP-ref Distance measurement result d of actual measurement meas With a currently measured predicted distance value P calculated based on the last positioning feedback ranging result lastpre Is the difference Δd of (2) meas-pre Whether it is reasonable:
if (DeltaP is satisfied FP-ref >ΔP FP_ref_th ||Δd meas-pre >Δd th ) Indicating that no head path is detected, estimating the output ranging channel quality as level=0, wherein i is logical or operation, and Δp FP_ref_th The threshold value of the energy fluctuation of the first path, deltad, allowed for the detection of the two receptions th A threshold is varied for the allowed ranging results;
if it does not meet (DeltaP FP-ref >ΔP FP_ref_th ||Δd meas-pre >Δd th ) The first diameter is detected, and then the next step of comparison judgment is carried out;
3): according to the first path signal energy P FP And the strongest path signal energy P max Energy difference ΔP of (2) FP-max And the first path signal energy P FP And received signal energy P Rx Energy difference ΔP of (2) FP-Rx Judging the channel level:
if (DeltaP is satisfied FP-max <ΔP FP_max_th1 &&ΔP FP-Rx <ΔP FP_Rx_th1 ) The first path signal is very strong, the multipath interference is very weak, and the output measurement is shownThe ranging channel quality is estimated as level=5, where Δp FP_max_th1 Is the first threshold value of the energy difference between the head path and the strongest path, delta P FP_Rx_th1 A first threshold value is the energy difference between the head path and the received signal;
if it does not meet (DeltaP FP-max <ΔP FP_max_th1 &&ΔP FP-Rx <ΔP FP_Rx_th1 ) Then the next step of comparison and judgment is carried out;
4): and adding the first path signal-to-noise ratio information, and continuously comparing with a relevant threshold value to evaluate the ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th2 &&ΔP FP-Rx <ΔP FP_Rx_th2 &&SNR FP >SNR th1 ) The first path signal is strong, the multipath interference is weak, and the output ranging channel quality is estimated to be level=4, wherein Δp FP_max_th2 Energy difference between first path and strongest path is second threshold, deltaP FP_Rx_th2 First path and received signal energy difference second threshold, SNR th1 A first threshold value for the first path signal-to-noise ratio;
if it does not meet (DeltaP FP-max <ΔP FP_max_th2 &&ΔP FP-Rx <ΔP FP_Rx_th2 &&SNR FP >SNR th1 ) Then the next step of comparison and judgment is carried out;
6): continue to use ΔP FP-max 、ΔP FP-Rx Sum SNR FP Comparing with a correlation threshold to evaluate ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th2 ||ΔP FP-Rx <ΔP FP_Rx_th2 )&&(SNR FP >SNR th2 ) The first path signal is moderate, the multipath interference is strong, the output ranging channel quality is estimated to be level=3, wherein the SNR th2 Is the second threshold of the first path signal to noise ratio.
If it does not meet (DeltaP FP-max <ΔP FP_max_th2 ||ΔP FP-Rx <ΔP FP_Rx_th2 )&&(SNR FP >SNR th2 ) Then the next step of comparison and judgment is carried out;
6): continue to use ΔP FP-max 、ΔP FP-Rx Sum SNR FP Comparing with a correlation threshold to evaluate ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th3 ||ΔP FP-Rx <ΔP FP_Rx_th3 ||SNR FP >SNR th3 ) The first path signal is weak, the multipath interference is serious, and the output ranging channel quality is evaluated as level=2, wherein deltap FP_max_th3 Third threshold value of energy difference between first diameter and strongest diameter, delta P FP_Rx_th3 First path and received signal energy difference third threshold, SNR th3 A third threshold value of the first path signal-to-noise ratio;
if it does not meet (DeltaP FP-max <ΔP FP_max_th3 ||ΔP FP-Rx <ΔP FP_Rx_th3 ||SNR FP >SNR th3 ) The first path signal is very weak, the multipath interference is very serious, and the output ranging channel quality is evaluated as level=1;
and 5, inputting the ranging channel quality evaluation result output in the step 4 into an LOS and NLOS evaluation window, and outputting whether the current ranging scene is LOS or NLOS by evaluating the data in the window, wherein the specific method comprises the following steps of:
firstly, calculating the ranging channel quality evaluation result by utilizing a sliding window with a certain length:
wherein N is the calculation result of the data in the LOS and NLOS scene judgment window for the nth time, E (N) is the length of the LOS and NLOS scene judgment window for the nth time;
then, the sliding window output result is evaluated and whether the current ranging scene is LOS or NLOS is output, and the method is as follows:
if E (n)>E th Outputting a current scene as an LOS scene, otherwise outputting the current scene as an NLOS scene, wherein E th To determine the threshold for LOS and NLOS scenarios.
Preferably, the steps ofIn step 1, the greater the distance measurement error between the predicted distance value measured last time and the actually measured distance measurement result, ω last The smaller omega last One-half, one-quarter, one-eighth or one-sixteenth.
Preferably, the threshold d of step 2) allowing fluctuation of the ranging result measth 30cm, the head-path energy difference threshold P in step 2, step 3) and in step 4, step 1) FPth 6dB.
Preferably, the calculating method of each relevant information value in the step 3 is as follows:
received signal energy P Rx ＝(P Rx1 +P Rx2 )/2，P Rx1 For the first received signal energy value, P, of DS-TWR base station Rx2 Receiving signal energy values for the DS-TWR base station for the second time;
maximum path signal energy P max ＝(P max1 +P max2 )/2，P max1 For the first time receiving the strongest path signal energy value, P, for DS-TWR base station max2 Receiving the strongest path signal energy value for the DS-TWR base station for the second time;
the energy of the first path signal is P FP ＝(P FP1 +P FP2 )/2，P FP1 For DS-TWR base station to receive signal energy of first path, P FP2 Receiving signal energy of a first path for a DS-TWR base station for the second time;
the noise energy is P noi ＝(P noi1 +P noi2 )/2，P noi1 For the first time receiving noise energy value, P, for DS-TWR base station noi2 A second received noise energy value for the DS-TWR base station;
the distance measurement result of the actual measurement is marked as d meas ；
The signal-to-noise ratio of the first path is SNR FP ＝P FP -P noi ，P FP Is the energy of the head path signal, P noi Is noise energy;
according to the first path signal energy P FP And a predicted initial diameter reference energy value P based on the last measurement lastref The energy difference DeltaP between the two is calculated FP-ref ＝P FP -P lastref ；
According to the first path signalNumber energy P FP And the strongest path signal energy P max The energy difference DeltaP between the two is calculated FP-max ＝abs(P FP -P max )；
According to the first path signal energy P FP And received signal energy P Rx The energy difference DeltaP between the two is calculated FP-Rx ＝abs(P FP -P Rx )；
Based on the measured distance measurement result d meas With a currently measured predicted distance value P calculated based on the last positioning feedback ranging result lastpre Calculating the distance measurement error delta d of the two meas-pre ＝d meas -P lastpre 。
Preferably, in step 4, 2), the threshold Δp of the first path energy fluctuation allowed by the two reception detections is set FP_ref_th 6dB, the allowable ranging result varies by a threshold Deltad th 50cm, the first threshold DeltaP of the difference between the energy of the first diameter and the strongest diameter in step 4) in step 3) FP_max_th1 1dB, a first threshold value delta P of the difference between the first path and the energy of the received signal FP_Rx_th1 3dB, the energy difference between the first path and the strongest path in step 4) is a second threshold value delta P FP_max_th2 6dB, a second threshold value delta P of the difference between the first path and the energy of the received signal FP_Rx_th2 9dB, first threshold SNR of first path SNR th1 40dB, the first path SNR second threshold SNR in step 4, 5) th2 32dB, the third threshold DeltaP of the difference between the energy of the first path and the strongest path in step 4) and 6) FP_max_th3 A third threshold delta P of 9dB, the difference between the first path and the energy of the received signal FP_Rx_th3 15dB, first path SNR third threshold SNR th3 24dB.
Preferably, in step 5, the length N of the LOS and NLOS scene determination window is typically 4, 8 or 16, and the threshold E of LOS and NLOS scenes is determined th 3.
The LOS and NLOS scene judging method based on ranging channel evaluation with the structure has the following beneficial effects:
1. a ranging channel quality evaluation method is provided: evaluating the current ranging channel quality by analyzing the received signal, and dividing the channel grade of the current ranging channel quality;
2. the output ranging channel quality evaluation result not only can be used for judging LOS and NLOS scenes, but also can be used for selecting and weighting the ranging result in the positioning process;
3. and judging the channel evaluation result in a certain window, outputting whether the current ranging environment is an LOS or NLOS scene in real time, and inhibiting the influence of uncertainty of the single channel evaluation result on LOS and NLOS scene evaluation.
Drawings
Fig. 1 is a flowchart of an embodiment of the LOS and NLOS scene determination method based on ranging channel estimation of the present invention;
fig. 2 is a flowchart of an embodiment of step 2 in the LOS and NLOS scene determination method based on ranging channel estimation of the present invention
Fig. 3 is a flowchart of an embodiment of step 4 in the LOS and NLOS scene determination method based on ranging channel estimation of the present invention;
fig. 4 is a diagram showing the output result of LOS and NLOS scene determination under a typical LOS scene by the LOS and NLOS scene determination method based on ranging channel estimation of the present invention;
fig. 5 shows the output result of LOS and NLOS scene determination in the scene where LOS and NLOS interact according to the LOS and NLOS scene determination method based on ranging channel estimation.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.
The LOS and NLOS scene judging method based on ranging channel estimation as shown in the figure comprises the following steps:
step 1, calculating a predicted distance value of next measurement based on a current positioning feedback ranging result, wherein the specific method comprises the following steps:
1) Firstly, updating the last speed updating result to obtain the current speed updating result, wherein the method comprises the following steps:
v cur ＝ω last *v last +(1-ω last )*(d cur -d last )
wherein v is cur Updating results for current speed，ω last For the weight value corresponding to the predicted distance value measured last time, the greater the distance measurement error between the predicted distance value measured last time and the actually measured distance measurement result is, ω last The smaller omega last One-half, one-fourth, one-eighth or one-sixteenth, v last D, for last speed update result cur Feedback ranging result for current positioning, d last And feeding back a ranging result for the last positioning. When the distance measurement error between the predicted distance value measured last time and the distance measurement result measured actually is smaller than 10cm, omega last In the case of a distance measurement error between the predicted distance value measured last time and the actually measured distance measurement result of 10cm or more and less than 20cm, ω last When the distance measurement error between the predicted distance value measured last time and the actually measured distance measurement result is more than or equal to 20cm and less than 40cm last Eighth, omega when the distance measurement error between the predicted distance value measured last time and the actually measured distance measurement result is 40cm or more last One sixteenth.
2) Then, feeding back the ranging result d according to the current positioning cur Update the result v with the current speed cur Calculating the predicted distance value d of the next measurement pre ：
d pre ＝d cur +v cur
Step 2, according to the current measured initial path energy value and noise energy P noi Calculating a predicted first-path reference energy value P based on the current measurement ref The specific method comprises the following steps:
1) Using a currently measured predicted distance value d calculated based on the last positioning feedback ranging result lastpre And a threshold d allowing fluctuation of the ranging result measth Summing to obtain the maximum reasonable distance measurement value d vld ＝d lastpre +d measth The method comprises the steps of carrying out a first treatment on the surface of the Threshold d allowing fluctuation of ranging result measth 30cm.
2) Then by the actually measured ranging result d meas And the maximum reasonable distance measurement value d vld Proceeding withComparing, if d meas >d vld The detection result shows that the distance measurement is unreasonable, and the energy of the head path is lower than the head path detection threshold value P detth The true head-path is not detected, and the current measurement based predicted head-path reference energy value P ref ＝P detth The method comprises the steps of carrying out a first treatment on the surface of the First diameter detection threshold P detth ＝P noi +15dB。
3) If d meas ≤d vld The ranging is reasonable, and the consistency of the energy of the first path detected twice needs to be judged:
first, the first path energy difference of the two detections is calculated:
ΔP FP ＝abs(P FP1 -P FP2 )
wherein DeltaP FP For the two-sided two-way ranging (DS-TWR) base station, the energy difference of the first path and the second path received by the base station, P FP1 For DS-TWR base station to receive signal energy of first path, P FP2 For the second time of receiving the signal energy of the first path of the DS-TWR base station, abs () is taken as absolute value operation;
then, the first path energy difference DeltaP is detected by two times FP And the first path energy difference threshold P FPth Comparing to determine whether the energy difference of the first path detected twice is reasonable: first path energy difference threshold P FPth Is the following.
When the energy difference delta P of the first path is detected twice FP Greater than the first path energy difference threshold P FPth The predicted first-path reference energy value based on the current measurement is P ref ＝min(P FP1 ,P FP2 ) Wherein, min () is the minimum value operation;
when the energy difference delta P of the first path is detected twice FP Less than or equal to the first path energy difference threshold P FPth The predicted first-path reference energy value based on the current measurement is P ref ＝max(P FP1 ,P FP2 ) Wherein, max () is the maximum value operation;
step 3, analyzing the signal received by the DS-TWR base station to obtain the following related information values: received signal energy P Rx Maximum path signal energy P max First path signal energy P FP Noise energy P noi Distance measurement results of actual measurementd meas 、SNR FP 、ΔP FP-ref 、ΔP FP-max 、ΔP FP-Rx And Δd meas-pre 。
The calculation method of each relevant information value in the step 3 is as follows:
received signal energy P Rx ＝(P Rx1 +P Rx2 )/2，P Rx1 For the first received signal energy value, P, of DS-TWR base station Rx2 Receiving signal energy values for the DS-TWR base station for the second time;
maximum path signal energy P max ＝(P max1 +P max2 )/2，P max1 For the first time receiving the strongest path signal energy value, P, for DS-TWR base station max2 Receiving the strongest path signal energy value for the DS-TWR base station for the second time;
the energy of the first path signal is P FP ＝(P FP1 +P FP2 )/2，P FP1 For DS-TWR base station to receive signal energy of first path, P FP2 Receiving signal energy of a first path for a DS-TWR base station for the second time;
the noise energy is P noi ＝(P noi1 +P noi2 )/2，P noi1 For the first time receiving noise energy value, P, for DS-TWR base station noi2 A second received noise energy value for the DS-TWR base station;
the distance measurement result of the actual measurement is marked as d meas ；
The signal-to-noise ratio of the first path is SNR FP ＝P FP -P noi ，P FP Is the energy of the head path signal, P noi Is noise energy;
according to the first path signal energy P FP And a predicted initial diameter reference energy value P based on the last measurement lastref The energy difference DeltaP between the two is calculated FP-ref ＝P FP -P lastref ；
According to the first path signal energy P FP And the strongest path signal energy P max The energy difference DeltaP between the two is calculated FP-max ＝abs(P FP -P max )；
According to the first path signal energy P FP And received signal energy P Rx The energy difference DeltaP between the two is calculated FP-Rx ＝abs(P FP -P Rx )；
Based on the measured distance measurement result d meas With a currently measured predicted distance value P calculated based on the last positioning feedback ranging result lastpre Calculating the distance measurement error delta d of the two meas-pre ＝d meas -P lastpre 。
Step 4, using the related information value obtained in step 3 to predict the initial diameter reference energy value P based on the last measurement lastref A predicted distance value P of the current measurement calculated based on the last positioning feedback ranging result lastpre The method for estimating the current ranging channel quality comprises the following steps of:
1): according to the energy difference delta P of the first path detected by the two times FP From the first path energy difference threshold Δp FPth Judging whether the energy of the first paths detected twice is consistent or not, wherein the energy of the first paths is different from a threshold value P FPth 6dB.
When DeltaP FP >ΔP FPth The first paths of the two receiving detection are inconsistent, and the output ranging channel quality is evaluated as level=0;
when DeltaP FP ≤ΔP FPth The first diameters of the two receiving detection are identical, and then the next step of comparison judgment is carried out;
2): determining the first path signal energy P FP And the predicted initial diameter reference energy value P based on the last measurement lastref Is the difference DeltaP of (1) FP-ref Distance measurement result d of actual measurement meas With a currently measured predicted distance value P calculated based on the last positioning feedback ranging result lastpre Is the difference Δd of (2) meas-pre Whether it is reasonable:
if (DeltaP is satisfied FP-ref >ΔP FP_ref_th ||Δd meas-pre >Δd th ) Indicating that no head path is detected, estimating the output ranging channel quality as level=0, wherein i is logical or operation, and Δp FP_ref_th The threshold value of the energy fluctuation of the first path, deltad, allowed for the detection of the two receptions th A threshold is varied for the allowed ranging results; two-time reception detection allowanceAllowable first path energy fluctuation threshold Δp FP_ref_th 6dB, the allowable ranging result varies by a threshold Deltad th 50cm.
If it does not meet (DeltaP FP-ref >ΔP FP_ref_th ||Δd meas-pre >Δd th ) And (5) describing that the first diameter is detected, and performing the next comparison judgment.
3): according to the first path signal energy P FP And the strongest path signal energy P max Energy difference ΔP of (2) FP-max And the first path signal energy P FP And received signal energy P Rx Energy difference ΔP of (2) FP-Rx Judging the channel level:
if (DeltaP is satisfied FP-max <ΔP FP_max_th1 &&ΔP FP-Rx <ΔP FP_Rx_th1 ) The first path signal is very strong, the multipath interference is very weak, and the output ranging channel quality is estimated to be level=5, wherein Δp FP_max_th1 Is the first threshold value of the energy difference between the head path and the strongest path, delta P FP_Rx_th1 A first threshold value is the energy difference between the head path and the received signal; first threshold delta P of energy difference between first path and strongest path FP_max_th1 1dB, a first threshold value delta P of the difference between the first path and the energy of the received signal FP_Rx_th1 Is 3dB.
If it does not meet (DeltaP FP-max <ΔP FP_max_th1 &&ΔP FP-Rx <ΔP FP_Rx_th1 ) And performing the next comparison judgment.
4): and adding the first path signal-to-noise ratio information, and continuously comparing with a relevant threshold value to evaluate the ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th2 &&ΔP FP-Rx <ΔP FP_Rx_th2 &&SNR FP >SNR th1 ) The first path signal is strong, the multipath interference is weak, and the output ranging channel quality is estimated to be level=4, wherein Δp FP_max_th2 Energy difference between first path and strongest path is second threshold, deltaP FP_Rx_th2 First path and received signal energy difference second threshold, SNR th1 A first threshold value for the first path signal-to-noise ratio; second threshold delta P of energy difference between first path and strongest path FP_max_th2 At the level of 6dB,second threshold deltaP of difference between first path and received signal energy FP_Rx_th2 9dB, first threshold SNR of first path SNR th1 40dB.
If it does not meet (DeltaP FP-max <ΔP FP_max_th2 &&ΔP FP-Rx <ΔP FP_Rx_th2 &&SNR FP >SNR th1 ) And performing the next comparison judgment.
5): continue to use ΔP FP-max 、ΔP FP-Rx Sum SNR FP Comparing with a correlation threshold to evaluate ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th2 ||ΔP FP-Rx <ΔP FP_Rx_th2 )&&(SNR FP >SNR th2 ) The first path signal is moderate, the multipath interference is strong, the output ranging channel quality is estimated to be level=3, wherein the SNR th2 A second threshold value for the first path signal-to-noise ratio; first-path signal-to-noise ratio second threshold SNR th2 Is 32dB.
If it does not meet (DeltaP FP-max <ΔP FP_max_th2 ||ΔP FP-Rx <ΔP FP_Rx_th2 )&&(SNR FP >SNR th2 ) And performing the next comparison judgment.
6): continue to use ΔP FP-max 、ΔP FP-Rx Sum SNR FP Comparing with a correlation threshold to evaluate ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th3 ||ΔP FP-Rx <ΔP FP_Rx_th3 ||SNR FP >SNR th3 ) The first path signal is weak, the multipath interference is serious, and the output ranging channel quality is evaluated as level=2, wherein deltap FP_max_th3 Third threshold value of energy difference between first diameter and strongest diameter, delta P FP_Rx_th3 First path and received signal energy difference third threshold, SNR th3 And is the third threshold of the first path signal to noise ratio. Third threshold delta P of energy difference between first path and strongest path FP_max_th3 A third threshold delta P of 9dB, the difference between the first path and the energy of the received signal FP_Rx_th3 15dB, first path SNR third threshold SNR th3 24dB.
If it does not meet (DeltaP FP-max <ΔP FP_max_th3 ||ΔP FP-Rx <ΔP FP_Rx_th3 ||SNR FP >SNR th3 ) The first path signal is very weak, the multipath interference is very serious, and the output ranging channel quality is evaluated as level=1;
and 5, inputting the ranging channel quality evaluation result output in the step 4 into an LOS and NLOS evaluation window, and outputting whether the current ranging scene is LOS or NLOS by evaluating the data in the window, wherein the specific method comprises the following steps of:
firstly, calculating the ranging channel quality evaluation result by utilizing a sliding window with a certain length:
wherein N is the calculation result of the data in the LOS and NLOS scene judgment window for the nth time, E (N) is the length of the LOS and NLOS scene judgment window for the nth time; the length N of LOS and NLOS scene determination windows is 4, 8 or 16.
Then, the sliding window output result is evaluated and whether the current ranging scene is LOS or NLOS is output, and the method is as follows:
if E (n)>E th Outputting a current scene as an LOS scene, otherwise outputting the current scene as an NLOS scene, wherein E th To determine the threshold for LOS and NLOS scenarios. Threshold E for judging LOS and NLOS scenes th 3.
In order to verify the validity of the LOS and NLOS scene judging method based on ranging channel estimation, the invention is verified by using actual measurement data. Fig. 4 shows the channel quality estimation result and LOS and NLOS scene determination result output in a typical LOS scene. Fig. 5 shows a scenario where LOS interacts with NLOS, and a channel quality evaluation result and a LOS and NLOS scenario judgment result are output and displayed. By utilizing actual measurement data to verify the invention, the invention can accurately judge the current LOS and NLOS scenes in real time, and the method can play a role in practical application.
Therefore, the LOS and NLOS scene judging method based on the ranging channel estimation is adopted, the current ranging channel quality is estimated by analyzing the received signal, and the channel grade where the current ranging channel quality is divided; judging the channel evaluation result in a certain window, and outputting whether the current ranging environment is an LOS or NLOS scene in real time; in the positioning process, different positioning strategies can be selected according to the evaluation results of the output LOS and the NLOS, so that the positioning robustness is improved.
The foregoing is a specific embodiment of the present invention, but the scope of the present invention should not be limited thereto. Any changes or substitutions that would be obvious to one skilled in the art are deemed to be within the scope of the present invention, and the scope is defined by the appended claims.

Claims (6)

1. A LOS and NLOS scene judging method based on ranging channel evaluation is characterized in that: the method comprises the following steps:
step 1, calculating a predicted distance value of next measurement based on a current positioning feedback ranging result, wherein the specific method comprises the following steps:
1) Firstly, updating the last speed updating result to obtain the current speed updating result, wherein the method comprises the following steps:
v cur ＝ω last *v last +(1-ω last )*(d cur -d last )
wherein v is cur To update the result, ω, for the current speed last For the weight value corresponding to the predicted distance value measured last time, v last D, for last speed update result cur Feedback ranging result for current positioning, d last Feeding back a ranging result for the last positioning;
2) Then, feeding back the ranging result d according to the current positioning cur Update the result v with the current speed cur Calculating the predicted distance value d of the next measurement pre ：
d pre ＝d cur +v cur
Step 2, according to the current measured initial path energy value and noise energy P noi Calculating a predicted first-path reference energy value P based on the current measurement ref The specific method comprises the following steps:
1) Using a currently measured predicted distance value d calculated based on the last positioning feedback ranging result lastpre And a threshold d allowing fluctuation of the ranging result measth Summing to obtain the maximum reasonable distance measurement value d vld ＝d lastpre +d measth ；
2) Then by the actually measured ranging result d meas And the maximum reasonable distance measurement value d vld Comparing, if d meas >d vld The detection result shows that the distance measurement is unreasonable, and the energy of the head path is lower than the head path detection threshold value P detth The true head-path is not detected, and the current measurement based predicted head-path reference energy value P ref ＝P detth First diameter detection threshold P detth ＝P noi +15dB；
3) If d meas ≤d vld The ranging is reasonable, and the consistency of the energy of the first path detected twice needs to be judged:
first, the first path energy difference of the two detections is calculated:
ΔP FP ＝abs(P FP1 -P FP2 )
wherein DeltaP FP For the two-sided two-way ranging (DS-TWR) base station, the energy difference of the first path and the second path received by the base station, P FP1 For DS-TWR base station to receive signal energy of first path, P FP2 For the second time of receiving the signal energy of the first path of the DS-TWR base station, abs () is taken as absolute value operation;
then, the first path energy difference DeltaP is detected by two times FP And the first path energy difference threshold P FPth Comparing to determine whether the energy difference of the first path detected twice is reasonable:
when the energy difference delta P of the first path is detected twice FP Greater than the first path energy difference threshold P FPth The predicted first-path reference energy value based on the current measurement is P ref ＝min(P FP1 ,P FP2 ) Wherein, min () is the minimum value operation;
when the energy difference delta P of the first path is detected twice FP Less than or equal to the first path energy difference threshold P FPth The predicted first-path reference energy value based on the current measurement is P ref ＝max(P FP1 ,P FP2 ) Wherein, max () is the maximum value operation;
step 3, analyzing the signal received by the DS-TWR base station to obtain the following related information values: received signal energy P Rx Maximum path signal energy P max First path signal energy P FP Noise energy P noi Distance measurement result d of actual measurement meas 、SNR FP 、ΔP FP-ref 、ΔP FP-max 、ΔP FP-Rx And Δd meas-pre ；
Step 4, using the related information value obtained in step 3 to predict the initial diameter reference energy value P based on the last measurement lastref A predicted distance value P of the current measurement calculated based on the last positioning feedback ranging result lastpre The method for estimating the current ranging channel quality comprises the following steps of:
1): the energy difference delta P of the first path of the two detection FP From the first path energy difference threshold Δp FPth Judging whether the energy of the primary diameters detected twice is consistent;
when DeltaP FP >ΔP FPth The first paths of the two receiving detection are inconsistent, and the output ranging channel quality is evaluated as level=0;
when DeltaP FP ≤ΔP FPth The first diameters of the two receiving detection are identical, and then the next step of comparison judgment is carried out;
2): determining the first path signal energy P FP And the predicted initial diameter reference energy value P based on the last measurement lastref Is the difference DeltaP of (1) FP-ref Distance measurement result d of actual measurement meas With a currently measured predicted distance value P calculated based on the last positioning feedback ranging result lastpre Is the difference Δd of (2) meas-pre Whether it is reasonable:
if (DeltaP is satisfied FP-ref >ΔP FP_ref_th ||Δd meas-pre >Δd th ) Indicating that no head path is detected, estimating the output ranging channel quality as level=0, wherein i is logical or operation, and Δp FP_ref_th The threshold value of the energy fluctuation of the first path, deltad, allowed for the detection of the two receptions th A threshold is varied for the allowed ranging results;
if it does not meet (DeltaP FP-ref >ΔP FP_ref_th ||Δd meas-pre >Δd th ) The first diameter is detected, and then the next step of comparison judgment is carried out;
3): according to the first path signal energy P FP And the strongest path signal energy P max Energy difference ΔP of (2) FP-max And the first path signal energy P FP And received signal energy P Rx Energy difference ΔP of (2) FP-Rx Judging the channel level:
if (DeltaP is satisfied FP-max <ΔP FP_max_th1 &&ΔP FP-Rx <ΔP FP_Rx_th1 ) The first path signal is very strong, the multipath interference is very weak, and the output ranging channel quality is estimated to be level=5, wherein Δp FP_max_th1 Is the first threshold value of the energy difference between the head path and the strongest path, delta P FP_Rx_th1 A first threshold value is the energy difference between the head path and the received signal;
if it does not meet (DeltaP FP-max <ΔP FP_max_th1 &&ΔP FP-Rx <ΔP FP_Rx_th1 ) Then the next step of comparison and judgment is carried out;
4): and adding the first path signal-to-noise ratio information, and continuously comparing with a relevant threshold value to evaluate the ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th2 &&ΔP FP-Rx <ΔP FP_Rx_th2 &&SNR FP >SNR th1 ) The first path signal is strong, the multipath interference is weak, and the output ranging channel quality is estimated to be level=4, wherein Δp FP_max_th2 Energy difference between first path and strongest path is second threshold, deltaP FP_Rx_th2 First path and received signal energy difference second threshold, SNR th1 Is the headA first threshold value of the path signal-to-noise ratio;
if it does not meet (DeltaP FP-max <ΔP FP_max_th2 &&ΔP FP-Rx <ΔP FP_Rx_th2 &&SNR FP >SNR th1 ) Then the next step of comparison and judgment is carried out;
5): continue to use ΔP FP-max 、ΔP FP-Rx Sum SNR FP Comparing with a correlation threshold to evaluate ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th2 ||ΔP FP-Rx <ΔP FP_Rx_th2 )&&(SNR FP >SNR th2 ) The first path signal is moderate, the multipath interference is strong, the output ranging channel quality is estimated to be level=3, wherein the SNR th2 A second threshold value for the first path signal-to-noise ratio;
if it does not meet (DeltaP FP-max <ΔP FP_max_th2 ||ΔP FP-Rx <ΔP FP_Rx_th2 )&&(SNR FP >SNR th2 ) Then the next step of comparison and judgment is carried out;
6): continue to use ΔP FP-max 、ΔP FP-Rx Sum SNR FP Comparing with a correlation threshold to evaluate ranging channel quality:
if (DeltaP is satisfied FP-max <ΔP FP_max_th3 ||ΔP FP-Rx <ΔP FP_Rx_th3 ||SNR FP >SNR th3 ) The first path signal is weak, the multipath interference is serious, and the output ranging channel quality is evaluated as level=2, wherein deltap FP_max_th3 Third threshold value of energy difference between first diameter and strongest diameter, delta P FP_Rx_th3 First path and received signal energy difference third threshold, SNR th3 A third threshold value of the first path signal-to-noise ratio;
if it does not meet (DeltaP FP-max <ΔP FP_max_th3 ||ΔP FP-Rx <ΔP FP_Rx_th3 ||SNR FP >SNR th3 ) The first path signal is very weak, the multipath interference is very serious, and the output ranging channel quality is evaluated as level=1;
and 5, inputting the ranging channel quality evaluation result output in the step 4 into an LOS and NLOS evaluation window, and outputting whether the current ranging scene is LOS or NLOS by evaluating the data in the window, wherein the specific method comprises the following steps of:
firstly, calculating the ranging channel quality evaluation result by utilizing a sliding window with a certain length:
wherein N is the calculation result of the data in the LOS and NLOS scene judgment window for the nth time, E (N) is the length of the LOS and NLOS scene judgment window for the nth time;
then, the sliding window output result is evaluated and whether the current ranging scene is LOS or NLOS is output, and the method is as follows:
if E (n)>E th Outputting a current scene as an LOS scene, otherwise outputting the current scene as an NLOS scene, wherein E th To determine the threshold for LOS and NLOS scenarios.
2. The LOS and NLOS scene determination method based on ranging channel estimation as claimed in claim 1, wherein: in step 1, the greater the distance measurement error between the predicted distance value measured last time and the actually measured distance measurement result, ω last The smaller omega last One-half, one-quarter, one-eighth or one-sixteenth.
3. The LOS and NLOS scene determination method based on ranging channel estimation as claimed in claim 1, wherein: threshold d in step 2) of 1) allowing fluctuation of ranging result measth 30cm, the head-path energy difference threshold P in step 2, step 3) and in step 4, step 1) FPth 6dB.
4. The LOS and NLOS scene determination method based on ranging channel estimation as claimed in claim 1, wherein: the calculation method of each relevant information value in the step 3 is as follows:
received signal energy P Rx ＝(P Rx1 +P Rx2 )/2，P Rx1 For the first received signal energy value, P, of DS-TWR base station Rx2 Receiving signal energy values for the DS-TWR base station for the second time;
maximum path signal energy P max ＝(P max1 +P max2 )/2，P max1 For the first time receiving the strongest path signal energy value, P, for DS-TWR base station max2 Receiving the strongest path signal energy value for the DS-TWR base station for the second time;
the energy of the first path signal is P FP ＝(P FP1 +P FP2 )/2，P FP1 For DS-TWR base station to receive signal energy of first path, P FP2 Receiving signal energy of a first path for a DS-TWR base station for the second time;
the noise energy is P noi ＝(P noi1 +P noi2 )/2，P noi1 For the first time receiving noise energy value, P, for DS-TWR base station noi2 A second received noise energy value for the DS-TWR base station;
the distance measurement result of the actual measurement is marked as d meas ；
The signal-to-noise ratio of the first path is SNR FP ＝P FP -P noi ，P FP Is the energy of the head path signal, P noi Is noise energy;
according to the first path signal energy P FP And a predicted initial diameter reference energy value P based on the last measurement lastref The energy difference DeltaP between the two is calculated FP-ref ＝P FP -P lastref ；
According to the first path signal energy P FP And the strongest path signal energy P max The energy difference DeltaP between the two is calculated FP-max ＝abs(P FP -P max )；
According to the first path signal energy P FP And received signal energy P Rx The energy difference DeltaP between the two is calculated FP-Rx ＝abs(P FP -P Rx )；
Based on the measured distance measurement result d meas With a currently measured predicted distance value P calculated based on the last positioning feedback ranging result lastpre Calculating the distance measurement error delta d of the two meas-pre ＝d meas -P lastpre 。
5. The LOS and NLOS scene determination method based on ranging channel estimation as claimed in claim 1, wherein: step 4, 2) of receiving and detecting the allowable threshold deltaP of the energy fluctuation of the first path twice FP_ref_th 6dB, the allowable ranging result varies by a threshold Deltad th 50cm, the first threshold DeltaP of the difference between the energy of the first diameter and the strongest diameter in step 4) in step 3) FP_max_th1 1dB, a first threshold value delta P of the difference between the first path and the energy of the received signal FP_Rx_th1 3dB, the energy difference between the first path and the strongest path in step 4) is a second threshold value delta P FP_max_th2 6dB, a second threshold value delta P of the difference between the first path and the energy of the received signal FP_Rx_th2 9dB, first threshold SNR of first path SNR th1 40dB, the first path SNR second threshold SNR in step 4, 5) th2 32dB, the third threshold DeltaP of the difference between the energy of the first path and the strongest path in step 4) and 6) FP_max_th3 A third threshold delta P of 9dB, the difference between the first path and the energy of the received signal FP_Rx_th3 15dB, first path SNR third threshold SNR th3 24dB.
6. The LOS and NLOS scene determination method based on ranging channel estimation as claimed in claim 1, wherein: in step 5, the length N of the LOS and NLOS scene judging window is 4, 8 or 16, and the threshold E of the LOS and NLOS scenes is judged th 3.
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