CN106154222A - A kind of method of the direction of travel utilizing radio-frequency signal detection people - Google Patents
A kind of method of the direction of travel utilizing radio-frequency signal detection people Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
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Abstract
A kind of method that the invention discloses direction of travel utilizing radio RF signal detection people, places an apparatus for transmitting signal Tx and two signal receivers Rx1, Rx2 respectively in known fixed position；Rx1, Rx2 are the most vertical with the line of Tx respectively, Tx Rx1 and Tx Rx2 equipment between do not stop；Signal uses OFDM modulation, is obtained the information of change in signal strength by measure channel state information；Extract the change of multi-frequency wireless channel by measuring radio RF signal, be calculated the direction of travel of people.Technical solution of the present invention must not be carried sensing equipment by people in cognitive method based on equipment and could be detected direction of travel and limited, it is possible to use existing wireless channel CSI numerical value, it is not necessary to carry out hardware modifications on wireless transmitting-receiving equipments, cost-effective；Can run with real-time continuous, there is convenient and practical, the detection advantage that error is less, precision is high.
Description
Technical field
The present invention relates to without device-aware technology, particularly relate to one and utilize radio RF (Radio Frequency, penetrates
Frequently) method of the direction of travel of signal detection people, utilizes the disturbance that radio RF signal is produced by the walking of people, by measuring also
Extract the change of multi-frequency wireless channel, be calculated the direction of travel of people.
Background technology
The walking manner of indoor people is a kind of important situation, and perception direction of travel can provide for a lot of application and support.Sentence
The prior art of the direction of travel of disconnected people the need of carrying with certain equipment, is roughly divided into two classes according to perceived people:
Without device-aware and perception based on equipment.
Wherein, perception based on equipment allows people to carry certain sensor, according to the difference of sensor, perception direction of travel
Method also have multiple.2014, the Nirupam Roy of University of Illinois (UIUC) was at document " I am a
Smartphone and I can Tell my UsersWalking Direction " in propose one utilize mobile phone perception room
Method WalkCompass of interior direction of travel.The method utilizes acceleration transducer present on mobile phone, it can be deduced that, people exists
Acceleration information in moving process, in the dimension of three, space.Acceleration information projects on horizontal plane that i.e. understand can level
Situation is accelerated in motion on face.WalkCompass differentiates that direction of travel is the process of two steps: 1) Nirupam Roy observes
To when people walks, step touches ground and produces a kind of special vibrations, and this vibrations are delivered to whole health, and can be placed on
The mobile phone of the most various positions can perceive.WalkCompass utilizes this vibrations as reference, scans forward signal,
Specific sample is extracted when trunk moves and accounts for walking main process.Signal is repaiied according to the data of mobile phone gyroscope subsequently
Just, to compensate walking the impact of the change of mobile phone attitude time.Finally, vector acceleration projects to be perpendicular in the plane of gravity,
Every a few step is averaged, to carry out the estimation of the local direction of travel relative to mobile phone；2) local direction based on mobile phone is reflected
Being mapped to globally in magnetic coordinate system, this is to utilize the geomagnetic sensor (electronic compass) in mobile phone to complete.Due to mobile phone magnetic
Induction compass is easily affected by Metals in Environments object, directly utilizes compass data error bigger.WalkCompass utilizes walking
Middle repetitive measurement compass data, carries out triangle polyester fibre, and the information of triangle polyester fibre can revise the data of compass.In walking one
In step, the distance of movement is shorter, and compass can be affected by environment same degree in repetitive measurement.Therefore, WalkCompass
Blind airmanship based on gyroscope is utilized to follow the tracks of the positional information of the repetitive measurement in moving process.
Differentiate that based on equipment the method for the moving direction of people completes also by continuous positioning, i.e. estimated by various methods
Mobile phone or wearable device etc., in indoor position, utilize different time to estimate the change of position to measure direction of travel.Side
To certainty of measurement depend on that the precision of location and unit interval can calculate the quantity of result.There is no the auxiliary of environmental unit
Under, only armrest holding equipment completes location, is presently mainly the method or method based on range finding/angle mated by information fingerprint
Complete.In finger print matching method, in region to be detected, certain signal meets two kinds of requirements: 1) ga s safety degree.I.e. detection zone
In territory, the signal of diverse location is different.2) time stability.I.e. within the regular hour (such as in some months), this signal
Diversity keeps constant.Algorithm is to utilize the existing sensor for certain signal in mobile phone, carries out place in advance a large amount of
Sampling, after being then passed through feature extraction and training, and positional information maps, and forms data base.This is the process of study.Make
Used time, the signal gathered is passed through same process, and the record in data base compares, and estimate position, general many employings
Bayes method.The method of fingerprint matching has a problem in that to be needed to sample the most in a large number and train, and every secondary environment, equipment
Resampling and training is needed after placement location change.
The existing location technology based on fingerprint utilizing the information such as Geomagnetic signal, wireless signal (GSM/WiFi RSSI), essence
Degree is about in room-level, far from reaching to estimate the requirement in indoor moving direction.And utilize physical layer CSI information to be obtained in that essence
The carefully location of some.5 pattern Shun in 2013 wait and construct in document " CSI-Based Indoor Localization " finely
Indoor positioning FILA (Fine-grained Indoor Localization) system, this system uses the base of WiFi CSI information
In the location of fingerprint matching, in the case of single AP, mean accuracy is about 3 meters；The situation mean accuracy of two AP is about 1.5
Rice.
During method work based on range finding, the distance of signal source relative to multiple known location can be measured respectively, so
After utilize method of geometry estimate position.The signal that distance-finding method utilizes reaches time ToF (TimeofFlight) information, distance etc.
It is multiplied by signal velocity in ToF.Sound ranging is used to arrange special equipment in needing room；Utilize the wireless signals such as WiFi then
Can be with multiplexing existing network facility.But, owing to radio is with light velocity propagation, need accurate arrival based on wireless range finding
The measurement of time, and accurate ToF measures and needs big bandwidth.Under the 20MHz bandwidth of existing WiFi agreement, it is possible to resolution time
Between be spaced apart 50 nanoseconds, about 15 meters precision.Owing to common room-sized is less than 15 meters, it is about the situation of 15 meters in precision
Under, the method cannot be distinguished by the different paths in 15 meters, therefore cannot meet requirement.
Method based on angle estimates position by angle A oA (Angleof Arrival) information that reaches measuring signal.
The estimation of angle needs aerial array, the multiple antenna of the most each receiving terminal.Antenna amount is the most, and angular error is the least.Existing skill
Art is mostly based on super resolution MUSIC algorithm or its a certain mutation.By framing signal relative to several ginsengs known
Examine the angle of position, can be with the position in signal calculated source by method of geometry.
Bears in 2014 is outstanding et al. at document (Phaser:Enabling Phased Array Signal Processing
OnCommodity WiFi Access Points) middle record, utilize the angle of arrival information of the WiFi signal of multiple AP to enter
Row location, can reach the mean accuracy of about 1 meter.But this precision needs each AP to be equipped with under 5 antennas to be obtained, and common
WiFi equipment is configured without so multiple antennas.2015, Xiong Jie was at document (ToneTrack:Leveraging Frequency-
Agile Radios forTime-Based Indoor Wireless Localization) in construct ToneTrack, should
System employs frequency hopping, is switched fast in multiple adjacent WiFi frequency ranges, to improve positioning precision.ToneTrack makes
With the WiFi AP of 6 special WARP hardware simulations, binding uses under 3 20MHz channels, reaches the average positioning accurate of 0.9 meter
Degree.
ManikantaKotaru in 2015 et al. utilizes WiFiCSI information to improve MUSIC algorithm, thus reduces
The antenna amount (SpotFi:Decimeter Level Localization Using WiFi) needed.SpotFi employs
6 AP, each AP assemble 3 antennas, and positioning precision is about 0.4 meter, have reached conventional each AP and have needed the suitable of 6 antennas
Result.In the case of using two AP, SpotFi reaches the precision of about 1.6 meters.
Scanning result, by scanning all channels of WiFi, is stitched together by Deepak Vasisht et al., to improve
Temporal resolution and range accuracy (Sub-Nanosecond Time of Flight on CommercialWi-Fi
Cards).The method only needs an AP, can reach 0.58 meter of positioning accurate in the case of there is LoS (Lineof Sight)
Degree, reaches 1.18 meters of positioning precisions in the case of NLoS (Non Lineof Sight).But the method needs at AP end and mobile phone
End synchronous vacations drives, it is achieved full band scan, it is impossible to directly realize on commercial WiFi basis of software.
Judge it is to utilize people that the impact of signal is detected based on the direction of travel without device-aware, generally use wireless
Signal.People need not carry any equipment when indoor walking.The most frequently used detection method is to utilize doppler principle.Doppler
Radar is exactly typical example.But realizing of radar is expensive, be difficult to miniaturization, detect and unreal for indoor moving
Border.Utilizing software radio to carry out examinations is another kind of implementation method, and advantage is can to send with precise synchronization, receiving terminal
Signal, but there is problems of accurate clock and synchronize and sample with high costs, and need to connect with cable to send and receiving terminal,
With the clock that offer is unified.This high-precision clock synchronizes two single transmission equipment and the reception being difficult in low cost and sets
Standby radio frequency chip realizes.The most existing radio frequency RF signal is utilized to carry out without equipment Passive Positioning and sense
The work known is less, and 5 pattern Shun in 2013 et al. construct Pilot system (Pilot:Passive Device-free Indoor
LocalizationUsing Channel State Information), Pilot is first and make use of WiFi physical layer CSI
Information carries out the work without device-aware and location, but is only capable of rough region and divides partition 3～the location reference point of 4 meters.
In sum, the cognition technology being currently based on equipment can reach the positioning precision of about 1 meter in the ideal case, needs
People's Portable device, and equipment needs and infrastructure coordinates to run aware software.There is the sense without equipment utilizing WiFi signal
The detection error of the location technology known, more than the detection error of employing perceptual positioning method based on equipment, reaches 3-4 rice, existing
The positioning precision of method without device-aware is the most coarse, and error is the biggest, it is difficult to be directly used in estimation direction of travel.Not yet go out at present
It is now able to directly utilize existing commercial WiFi chip and realizes measuring the technology of direction of travel.
Summary of the invention
In order to overcome above-mentioned the deficiencies in the prior art, the present invention provides a kind of new method without device-aware, utilizes wireless
The method of the direction of travel of electricity RF signal detection people, utilizes the disturbance that radio RF signal is produced by the walking of people, by measuring
And extract the change of multi-frequency wireless channel, it is calculated the direction of travel of people.The present invention facilitates easy-to-use, detects with real-time continuous,
And accuracy of detection is high.
The principle of the present invention is: radio wave is impacted by the mobile meeting of people.This impact shows the health meeting of people
Reflection radio wave, the electric wave of reflection, together with the Signal averaging originally sent from Tx-Rx (transmission-reception), is formed new
Signal intensity.When people is at indoor moving, the path of the radio signal process of health reflection constantly changes, and
The path of LoS does not change.Then, the radio wave from two paths can occur superposition, and the effect of superposition takes
Certainly in the phase relation of the radio signal from two paths.If two path phase identical (or close), from people's
Reflected signal can strengthen the signal from LoS；If two path phase are contrary, the reflected signal from people can weaken from
The signal of LoS.This phenomenon can be described by Fresnel region model.Fresnel region model is two focuses with Tx and Rx
Concentration ellipse bunch, the wherein distance of some distance one focusing on the ellipse of innermost layer and half wavelength more than LoS length, between ellipse
There is no intersection point, the distance of point two focuses of distance on later outer layer ellipse and half wavelength more than adjacent inner layer ellipse.
On the different ellipses of Fresnel region, signal forms crest and trough, is alternately present.Thus, people can wear at indoor continuous moving
More Fresnel region, causes the change repeatedly that signal is strong and weak, produces the change of similar sinusoidal wave sample.The effect of superposition depends on using
Radio wavelength and the distance of people a pair Tx-Rx of distance.The intensity of wireless signal can use receiving terminal RSSI
(Received Signal StrengthIndicator) portrays.
The present invention utilizes the wireless signal that OFDM modulates, and perception enters the direction of travel of the people in room.Especially by indoor
The radio signal of fixed position sends equipment and the equipment of reception, utilizes the channel condition information gathered on reception equipment to count
Calculate and estimate the direction of travel of people, to overcome people must carry this constraint of sensing equipment.The radio signal of OFDM modulation
Containing the subchannel of multiple frequencies, between subchannel, difference on the frequency is generally spaced equal.And when the person moves, different in different subchannels
The variation tendency of the radio signal strength of wavelength is the most asynchronous.By measuring the priority of signal intensity fluctuation in different subchannel
Relation, it can be determined that go out the people's mobile relation relative to a pair Tx-Rx.It is logical for portraying the signal intensity of each subchannel in OFDM
Cross what measure channel state information (ChannelStateInformation, CSI) completed.CSI information describes each
OFDM subchannel, wireless signal from transmitting terminal arrive receiving terminal time, the attenuation of intensity and the situation of change of phase place.
The technical scheme that the present invention provides is as follows:
The processing method of a kind of direction of travel utilizing radio RF signal detection people, puts at known fixed bit respectively
Put an apparatus for transmitting signal Tx (such as: WiFi wireless router or wireless access point AP), two signal receiver Rx (examples
As: PC PC, intelligent television etc.), two Rx are the most vertical with the line of Tx respectively, and signal uses OFDM modulation, and
Measure channel state information (CSI information) can be passed through and obtain the information of change in signal strength, enter indoor people and need not take
Carry any equipment.Do not stop between application claims Tx-Rx, there is stronger LoS (Lineof Sight) path；
The processing method utilizing the direction of travel of radio RF signal detection people comprises the steps:
1) data acquisition and pretreatment
A) Tx launches radio signal, gathers CSI information at two Rx ends.Complete CSI information includes OFDM subchannel
Transmission characteristic information (single plural number describe), transmission antenna numbering and reception antenna numbering when gathering, gather the moment
Timestamp.Tx sends signal and does not require the most at equal intervals, can be along with the normal transmission of RFDC；
B) after the CSI signal time sequence collected being taken absolute value square, so that complex values is become real number；
C) to the non-homogeneous CSI signal time sequence interpolations containing timestamp collected, uniform CSI signal time is formed
Sequence
D) to the application filtering of CSI signal time sequence, to remove noise and high-frequency fluctuation；
2) feature extraction
A) it is window to overall time series cutting；
B) to each window, the time delay between OFDM different sub carrier is compared；
C) according to the relation of time delay between subcarrier, determine whether people there occurs movement relative to every couple of Tx-Rx, identify mobile
Belong near relation or away from relation；
D) to each window, quantity period of waves is estimated, as displacement；
Specifically, it is time window to uniform channel status information time series entirety cutting；To each time window, logical
Crossing calculating and compare the time delay between OFDM different sub carrier, the distribution of time delay in detection a period of time, respectively as people relative to Tx-
Rx1 equipment to or the Tx-Rx2 equipment centering corresponding moving direction of single pair of equipment, thus identify people relative to Tx-Rx1 equipment pair
Or Tx-Rx2 equipment is to whether there occurs the movement that distance changes；And estimate number period of waves of each time window of correspondence
Amount, as relative to this displacement to equipment；Described there occurs distance change movement refer to people relative to certain to equipment
To there occurs movement, and to the Tx of equipment, people adds that the path sum of people's distance Rx there occurs change apart from this；Now, one
The value of symbol sum being distributed the time delay between the subcarrier in time window corresponding on equipment is more than set threshold value；
3) direction estimation: the position of transmitting antenna of Tx is remembered into zero, builds cartesian coordinate system；By two Rx's
Two coordinate axess relative to origin position are remembered in reception antenna position；
If a) relative to two pairs of Tx-Rx equipment, people all there occurs that the movement that distance changes (there occurs the shifting that distance changes
Move and refer to that people occurs obvious with the distance sum of Tx and Rx equipment after there occurs movement relative to a pair Tx-Rx equipment respectively
Change, show as on Fresnel region model, have substantially oval from outer layer/internal layer ellipse inner layer/outer layer movement, be substantially
Closer or far from relation), then utilize method of geometry calculate moving direction；Under this situation, the computational methods in direction are as follows: by one
In the section time, people's moving direction relative to every couple of Tx-Rx and distance project on corresponding coordinate axle, moving direction away from/
Near positive and negative for relative to corresponding coordinate axle of relation projection, displacement is the period of waves time of CSI waveform in this period
Number (by 2d) obtains).After projecting two coordinate axess, the direction of the vector of synthesis is i.e. the people direction at indoor moving；
If b) people has relative to two pairs of Tx-Rx equipment and only there occurs that the movement that distance changes (is on a pair Tx-Rx
The most close/away from relation), another is to close on Tx-Rx/inconspicuous away from relation, then utilize empirical method to estimate mobile
Direction.
Under this situation, the c of step 2) testing result of step a pair performance of at least a part of which inconspicuous in two couples of Tx-Rx
(people relative to this transceiver be there occurs mobile after respectively with this distance sum approximately equal to transceiver, do not have
Occurring substantially to change, i.e. this moves is not to there occurs the movement that distance changes.Show on Fresnel model, be equivalent to same
Layer is oval mobile), then experience estimation method is: projects the Distribution Value that vector is time delay of two coordinate axess, projects two
After individual coordinate axes, the direction of the vector of synthesis is i.e. the people direction at indoor moving.
If c) close/the most inconspicuous away from relation on two couples of Tx-Rx, then judge not to be moved for people.
Beneficial effects of the present invention:
The present invention provides a kind of new method without device-aware, utilizes the side of the direction of travel of radio RF signal detection people
Method, utilizes the disturbance that radio RF signal is produced by the walking of people, changes by measuring and extract multi-frequency wireless channel, calculates
Obtain the direction of travel of people.
The present invention utilizes the channel condition information gathered on transmission or reception equipment to carry out calculating thus estimates the walking of people
Direction, must not be carried sensing equipment by people in cognitive method based on equipment and could detect direction of travel and limited, can be in order to
With existing wireless channel CSI numerical value, it is not necessary to carry out hardware modifications on wireless transmitting-receiving equipments, cost-effective；Detect by mistake simultaneously
Difference is less, and detection error has reached to be equivalent to the multiple sensors such as accelerometer, gyroscope that are integrated with based on equipment
The angle detecting precision of WalkCompass method.This method can be run with real-time continuous, it is not necessary to gathers ambient signal in advance and refers to
Stricture of vagina.People gets final product perception in indoor walking one to two step and calculates moving direction, and technical solution of the present invention is better than existing method, has
The advantage that practicality is high, precision is higher.
Accompanying drawing explanation
Schematic diagram is placed by radio in Fig. 1 embodiment of the present invention；
Wherein, dotted line represents detection region；TX is radio transition equipment；RX1, RX2 are respectively radio receiving equipment 1
With radio receiving equipment 2.
Fig. 2 embodiment of the present invention utilizes the calculation process frame of the method for the direction of travel of radio RF signal detection people
Figure.
Detailed description of the invention
Below in conjunction with the accompanying drawings, further describe the present invention by embodiment, but limit the model of the present invention never in any form
Enclose.
The present invention provides a kind of method of direction of travel utilizing radio RF signal detection people, utilizes the walking of people to nothing
The disturbance that line electricity RF signal produces, changes by measuring and extract multi-frequency wireless channel, is calculated the direction of travel of people.
The present invention implement time, need in room place a known fixed location apparatus for transmitting signal Tx (such as:
WiFi wireless router or wireless access point AP), the signal receiver Rx of two known fixed location (such as: PC people's electricity
Brain, intelligent television etc.), and two Rx equipment are the most vertical with the line of Tx respectively, signal uses OFDM modulation technique, and energy
The enough information by measuring CSI acquisition of information change in signal strength.Enter indoor people to need not carry any equipment.The present invention
Require not stop between Tx-Rx, there is stronger LoS path.Signal is placed by radio in Fig. 1 embodiment of the present invention
Figure；Radio in the present embodiment includes a radio transition equipment TX and two radio transition equipments RX1, RX2.
Wherein, dotted line represents detection region.The method utilizing the direction of travel of radio RF signal detection people in Fig. 2 embodiment of the present invention
Calculation process block diagram.The detailed description of the invention of the present invention is as follows:
1) channel condition information CSI is obtained；
A) CSI information both can gather at two wireless device receiving terminals respectively, it is also possible at wireless device transmitting terminal collection
Middle collection.Every a pair Tx-Rx equipment room produces one group of CSI time series, and two groups of Tx-Rx produce altogether two groups of CSI time serieses.
B) information collected concentrates in together and processes.If CSI information is two receiving terminal collections, then need to lead to
Cross network to be pooled to same process node and be further processed；If CSI information is in transmitting terminal collection, then can directly exist
Sending node processes.
C) collection of CSI information is that the course synchronization following communication completes.General before each communication transfer, measure one
Secondary CSI numerical value.
D) the different subchannels of OFDM coding can produce respective CSI measured value, it may be assumed that CSI measurement each time includes different frequency
The CSI numerical value of the OFDM subchannel of rate.
E) CSI the most constantly samples, and forms time series.
Then square f) each CSI numerical value is taken absolute value,.The purpose taken absolute value is long to plural number delivery.
G) wanting accurately to judge the direction of travel of indoor people, CSI sample rate should be at least up to 300Hz；
2) time series of two receiving terminal CSI of alignment
A) the CSI numerical value collected can comprise the timestamp that network interface card is formed, and without absolute time in timestamp, only contains only
The enumerator that internal crystal oscillator produces, timestamp absolute value that therefore different receiving terminals produce also differs.This step needs each
Subtract each other before and after the CSI seasonal effect in time series timestamp of receiving terminal, form relative time stamp.That is:, after subtracting each other, timestamp represents each
The time interval that CSI measures, represents with the quantity of crystal oscillator counting.
B) relative time stamp is multiplied by network interface card crystal oscillator frequency, i.e. obtains the timestamp of relative time；
C) the relative time stamp produced by two receiving terminals carries out maximum common subsequence matching algorithm, finds out public sub-sequence
It is listed in the original position of two relative time stamps；
D) original position numerical value is subtracted each other poor, according to original position difference alignment two receiving terminals CSI time sequence
Row；
3) CSI waveform is carried out interpolation
A) timestamp of relative time that 2b step is produced adds up, and obtains starting, from 0, the CSI time series that clocks.
That is: the timestamp of the relative time of 2b represents the time interval that adjacent twice CSI measures, and after adding up, represents from 0 moment started
Value；
B) utilize Spline Spline Interpolation Method that CSI timestamp is carried out interpolation, during to obtain time interval uniform CSI
Between sequence；
4) CSI waveform is carried out noise reduction
A) use Savitzky-Golay smoothing method that CSI time series waveform is carried out noise reduction, Savitzky-Golay
The parameter of noise reduction is chosen as: select 3 order polynomials, and window size is for comprising 1 CSI period of waves preferably；
B) two CSI time serieses are applied Savitzky-Golay smoothing processing several times respectively, smoother to obtain
Curve.
5) time delay between subcarrier is calculated
A) use sliding window that CSI time series burst, window size are set to 0.1 second；
B), in window, the CSI waveform of multiple OFDM subchannels is standardized.Standardized method is: calculate each
OFDM subchannel CSI time series meansigma methods in this window, deducts this by the CSI sequence in this OFDM subchannel average
Value so that CSI waveform becomes to do around 0 and fluctuates up and down；
C) calculate the signal cross-correlation between different sub carrier, take cross-correlation and reach the side-play amount at maximum, as two
Time delay between subcarrier；
6) relative movement distance in a period of time is estimated
A) using sliding time window by CSI time series burst, window size is set to 0.5 second, overlapping between window
50%；
B) each window is utilized fast Fourier transform FFT, obtain quantity period of waves of CSI in this time window；
C) each OFDM subcarrier application b being walked algorithm, in obtaining window, quantity period of waves of each subcarrier, takes sub-load
Ripple period of waves quantity meansigma methods as the estimation of displacement；This displacement distance spatially of getting along well are corresponding,
It is only used for calculating angle；
D) in a period of time, the displacement of accumulation is the displacement sum that each subwindow calculates, and removes windows overlay
Part；
7) distribution of time delay in detection a period of time, it is thus achieved that people is relative to the moving direction of a pair Tx-Rx equipment；
A) sliding window is used by 5) result burst that step carrier wave time delay calculates, window size is set to 1 second；
B) in window, by 5) delay value that calculates of step takes sign function sgn, it may be assumed that to positive number, result is 1, to negative, and knot
Fruit is-1, and to 0, result is 0；
C) by all delay values in 1 second window, it is added after taking symbol, obtains the distribution of delay value；
D) arranging threshold value is in 1 second window the 1/4 of the quantity of effective delay value；
E) when the distribution of the delay value obtained when step 7c is more than threshold value set by step 7d, people relative to this to Tx-
The moving direction at Rx equipment line midpoint is just, now people is away from Tx-Rx equipment；The distribution of the delay value obtained when step 7c is little
When the negative value of the threshold value set by step 7d, direction is negative, and now people is near Tx-Rx equipment；When the time delay that step 7c obtains
When the distribution of value is between positive negative threshold value, moving direction is inconspicuous, and direction is 0, it is believed that people does not move or connects along Tx-Rx
The parallel angle of line moves；
8) moving direction of people is estimated
A) position of transmitting antenna of Tx is remembered into zero, build cartesian coordinate system；
B) two coordinate axess relative to origin position are remembered in the reception antenna position of two Rx；
If what c) testing result in step 7e all showed on two couples of Tx-Rx is obvious, it may be assumed that the direction delay value of 7e step divides
The absolute value of cloth is more than threshold value.Then the computational methods in direction are as follows: people's moving direction relative to every couple of Tx-Rx and distance are thrown
Shadow on corresponding coordinate axle, moving direction close/be the positive negative in direction away from relation, be mapped as relative to each coordinate
The positive and negative 7e of axle, displacement is the fluctuation number of times 6d of CSI waveform in a period of time.After projecting two coordinate axess, synthesis
The direction of vector is i.e. the people direction at indoor moving；
If the d) e of step 7) testing result of step a pair performance of at least a part of which inconspicuous in two couples of Tx-Rx, i.e. 7e)
Step direction be 0, then experience estimation method is: by 7c) step two to Tx-Rx on calculate delay value be distributed be projected directly at two phases
Answer on coordinate axes.After projecting two coordinate axess, the direction of the vector of synthesis is i.e. the people direction at indoor moving.
Below by example, the present invention will be further described.
Universal due to indoor WiFi equipment, following example we utilize WiFi signal to detect the direction of travel of people.
Utilize the WiFi router of the support 802.11n agreement being arranged in 5G frequency range lift-launch omnidirectional antenna as signal transmitting terminal Tx, profit
With two lift-launch omnidirectional antennas, it is mounted with that the MiniPC of Intel5300 wireless network card is as signal receiving end.802.11n and with
After agreement support OFDM modulation.Utilizing Linux CSItools can gather CSI data, the CSI collected comprises 30 sons and carries
The information of ripple.The present invention is utilized to provide the idiographic flow of direction of travel of method detection people as follows:
1) being placed on the transmitting antennas orthogonal ground on router, its position mark is zero Tx, is placed on room one
Angle；
2) being placed on the transmitting antennas orthogonal ground of two MiniPC, its position mark, for receiving Rx1 and Rx2, is placed on room
Between another two jiaos.The wire definition of Tx and Rx1 is x-axis, and the wire definition of Tx and Rx2 is y-axis, sets up coordinate system；
3) continuous acquisition CSI data on Rx1 and Rx2, and be sent to a PC by WiFi network and focus on；
4) appropriate data communication is produced in WiFi router side, to reach the CSI sample rate of about 300Hz；
5) CSI data prediction is carried out, it may be assumed that to the CSI time series interpolation collected, then carry out S-G filtering.Interpolation
Time, use spline spline method, to reach 300Hz and above uniform sampling.Savitzky-Golay filtering uses 3 times
Multinomial, window size is set to about CSI period of waves.It is about sample rate to round after 40, then ensures that window
Size is odd number (requirement of S-G filtering algorithm).
6) split window calculates the time delay between subcarrier.Window is set to 0.1 second, slides in the way of overlapping 50%.Time delay
Computational methods be to calculate the cross-correlation between two different sub carrier.Taking the displacement at cross-correlation maximum is delay value.
7) distribution of computation delay value.The statistics of distribution needs the most longer window, such as: take the window of 1 second, then press
According to 0.1 second window calculation, the delay value of overlapping 50% had 20.Take after symbol cumulative, then the span of accumulated value [-
20,20] between.Threshold value is set to 20/4=5.
8) direction is judged.Being distributed between 20 and 5 of time delay, it is judged that for positive direction；Time delay be distributed in-5 with-20 it
Between, it is judged that for negative direction；Being distributed between-5 and 5 of time delay, directional information is indefinite.
9) displacement is judged, i.e. the fluctuation number of times of CSI in statistics a period of time.Such as, select the time window of 1 second,
The fluctuation number of times of CSI is estimated by fast Fourier transform FFT method.By the CSI time series of 1 second after FFT, shape
The sequence of Cheng Xin, the location number of the maximum in sequence is the fluctuation number of times estimated.
10) direction of two dimensional surface is synthesized.If directional information is all clear and definite on two couples of Tx-Rx, then the vector of two-dimensional directional can
To project on every couple of Tx-Rx, it may be assumed that project in x-axis and y-axis.The value of projection is that the 9th step fluctuation number of times is just being multiplied by the 8th step
Negative value.Such as: the direction projecting to x-axis is negative, and fluctuation number of times be 3 times；The direction projecting to y-axis is just, and fluctuation number of times
Be 4, then availability vector (-3,4) represents the direction of movement.
11) if in twice Tx-Rx direction, the directional information having a pair is indefinite, then the vector of two-dimensional directional utilizes experience
Method is estimated, i.e. the projection of x/y axle is respectively adopted the accumulated value of the 7th step and replaces.
12) by taking the calculating of arctan function, x/y axle the angle of the vector represented is the actual direction of walking.Example
As: if the vector of movement is (-3,4), then the angle moved is-53.13 degree.
It should be noted that publicizing and implementing the purpose of example is that help is further appreciated by the present invention, but the skill of this area
Art personnel are understood that various substitutions and modifications are all without departing from the present invention and spirit and scope of the appended claims
Possible.Therefore, the present invention should not be limited to embodiment disclosure of that, and the scope of protection of present invention is with claim
Book defines in the range of standard.
Claims (10)
1. the method utilizing the direction of travel of radio-frequency signal detection people, is characterized in that, respectively known fixing
An apparatus for transmitting signal Tx and two signal receivers Rx1, Rx2 are placed in position；Rx1, Rx2 line with Tx respectively to the greatest extent may be used
Can be vertical, Tx-Rx1 equipment to and Tx-Rx2 equipment between do not stop；Signal uses OFDM modulation, by measuring channel shape
The information of state information retrieval multi-frequency OFDM subchannel wireless channel change, is calculated the direction of travel of people；Including walking as follows
Rapid:
1) data acquisition acquisition and pretreatment: Tx launches radio signal, the most constantly gathers channel condition information, is formed
Time series, preprocessed obtains uniform channel status information time series；
2) feature extraction is carried out, including:
It is time window to described uniform channel status information time series entirety cutting；
To each time window, comparing the time delay between OFDM different sub carrier by calculating, in detection a period of time, time delay divides
Cloth, respectively as people relative to Tx-Rx1 equipment to or the Tx-Rx2 equipment centering corresponding moving direction of single pair of equipment, thus know
Others is relative to the movement to whether there occurs that distance changes of certain equipment；
Estimate quantity period of waves of corresponding each time window, as people relative to this displacement to equipment；
3) travel direction is estimated, obtains the direction of travel of the moving direction of people, i.e. people；Including two kinds of situations:
A) when people relative to Tx-Rx1 and Tx-Rx2 two relation of equipment is there occurs that distance changes mobile time, utilize several
Where method is calculated the moving direction of people；
B) there occurs, relative to one pair of which equipment, the movement that distance changes as people, and people is relative to another shifting to equipment generation
Dynamic be not distance change mobile time, utilize empirical method to estimate to obtain the moving direction of people.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 1, is characterized in that, step 1)
Described Tx launches radio signal for normally sending radio signal along with RFDC；Described channel condition information includes
Transmission antenna numbering, reception antenna numbering and the timestamp in collection moment when the transmission characteristic information of OFDM subchannel, collection.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 1, is characterized in that, step 1)
Data acquisition acquisition channel condition information is followed the course synchronization of communication and is completed；Specifically concentrate at wireless device transmitting terminal and adopt
Collection, or gather respectively at two wireless device receiving terminals；The information collected is concentrated in together and carries out pretreatment.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 3, is characterized in that, described letter
Channel state information sample rate is at least up to 300Hz.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 3, is characterized in that, work as channel
Status information is when two wireless device receiving terminal Rx gather respectively, and need to align two wireless device receiving terminal channel status letters
The time series of breath, described alignment comprises the steps:
A) the channel condition information numerical value collected comprises the timestamp that network interface card is formed, by the channel condition information of each receiving terminal
Subtract each other before and after seasonal effect in time series timestamp, form relative time stamp；Described relative time stamp represents that each channel condition information is surveyed
The time interval of amount, represents with the quantity of crystal oscillator counting；
B) described relative time stamp is multiplied by network interface card crystal oscillator frequency, obtains the timestamp of relative time；
C) the relative time stamp produced by two receiving terminals, by maximum common subsequence matching algorithm, is found out common subsequence and is existed
The original position of two relative time stamps；
D) original position numerical value is subtracted each other poor, further according to original position difference alignment two receiving terminals channel condition information
Time series.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 1, is characterized in that, step 1)
The pretreatment of described channel condition information includes: after the channel condition information time series collected being taken absolute value square；Right
Channel condition information time series carries out interpolation, forms uniform channel status information time series；To the channel condition information time
Sequence, by filtering noise reduction, removes noise and high-frequency fluctuation.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 6, is characterized in that, specifically profit
By Spline Spline Interpolation Method, channel condition information time series is carried out interpolation, obtain the uniform channel status of time interval
Information time sequence；Channel condition information time series waveform is dropped by specifically used Savitzky-Golay smoothing method
Make an uproar.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 1, is characterized in that, step 2)
Described calculate the distribution of OFDM subcarrier time delay in a period of time, it is thus achieved that moving direction, identify people relative to certain equipment to whether
There occurs the movement that distance changes；Specifically include following steps:
A) employing arranges sliding window by channel condition information time series burst；
B) in sliding window, multiple OFDM subchannel channel condition information waveforms are standardized；
C) calculate the signal cross-correlation between different OFDM subcarrier, take cross-correlation and reach the side-play amount at maximum, as two
Delay value between subcarrier；
D) use sliding window that the delay value between c) described different sub carrier is carried out burst；
E) in sliding window, the delay value between c) described different sub carrier is taken sign function sgn, obtain result 1 ,-1 or 0；
F) all results added that will e) obtain, obtain the distribution of delay value；
G) threshold value is set according to the quantity of effective delay value in sliding window；
H) when the distribution of delay value is more than set threshold value, the movement away from equipment occurring, direction is just；When dividing of delay value
When cloth is less than the threshold value born, the movement near equipment occurring, direction is negative；When the distribution of delay value is between the positive negative value of threshold value
Between time, for not having mobile or along described equipment, the angle that line is parallel being moved；
I) as people relative to described equipment to there occurs movement, and people respectively with apparatus for transmitting signal and the signal of this equipment centering
When the distance sum of reception equipment there occurs change, identify and obtain people relative to this equipment to there occurs apart from the movement changed.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 1, is characterized in that, step 2)
Described estimation obtains the fluctuation number of times of each time window, as displacement, specifically includes following steps:
A) use sliding window by channel condition information time series burst, arrange between described sliding window size and sliding window
Duplication；
B) each sliding window is utilized fast Fourier transform FFT method, obtain channel condition information ripple in this sliding window
Dynamic amount of cycles；
C) each OFDM subcarrier is performed above-mentioned steps b), obtain the fluctuation quantity of each subcarrier, take the fluctuation number of subcarrier
The meansigma methods of amount is as the estimated value of displacement, and the estimated value of this displacement is for calculating the angle of direction of travel；
D) the estimated value sum of the displacement calculated by each sliding window, removes the part of windows overlay, during as one section
The displacement of interior accumulation.
The method utilizing the direction of travel of radio-frequency signal detection people the most as claimed in claim 1, is characterized in that, step
3) the described moving direction utilizing method of geometry to be calculated people particularly as follows:
Moving direction and the displacement of equipment are projected to accordingly by people in a period of time relative to Tx-Rx1 and Tx-Rx2 two
On coordinate axes, the direction of synthesized vector is i.e. the people direction at indoor moving；Described people is relative to Tx-Rx1 and Tx-Rx2
The moving direction of two pairs of equipment away from/near positive and negative for relative to corresponding coordinate axle of relation projection；Described displacement by
In this period, number of times period of waves of channel condition information waveform obtains；
Described utilize empirical method estimate obtain people moving direction particularly as follows:
Using the distribution of described time delay as the vector projecting two coordinate axess, the Distribution Value of time delay is projected two coordinate axess
After, the direction of the vector of synthesis is i.e. the people direction at indoor moving.
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