CN104076349A - Passive type moving target locating method on the basis of Doppler frequency shift - Google Patents

Abstract

The invention provides a passive type moving target locating method on the basis of Doppler frequency shift. The method comprises the specific steps that firstly, a scene is set; secondly, a locating signal is generated; thirdly, the locating signal is located, a locating angle is determined; fourthly, angle information, corresponding to a directive antenna, of three beacons is determined according to sub-channel designators stored by the three beacons, and therefore the position of a moving target is determined. According to the method, the directions, relative to the three beacons, of the target can be determined according to Doppler influence on beacon sending frequency from movement of the moving target, the single moving target can be located in the passive locating scene, little locating equipment, short locating time and low locating cost are used, and the effect of locating the passive type moving target is improved.

Description

A kind of passive type Moving objects location method based on Doppler shift

Technical field

The invention belongs to wireless network positioning field, be specifically related to a kind of passive type localization method, particularly relate to a kind of passive type Moving objects location method based on Doppler shift.

Background technology

Compare with the method for active location (as GPS (GPS), radio-frequency (RF) identification (RFID), localization method based on FM), without equipment passive type location, in a lot of application of wireless network, become a focus.For example, be applied in safety and intruding detection system, wild animal detection, shopping and retail custom analysis, old age or physical disabilities' assistance.In these scenes, localizing objects is avoided and to be carried or to be inconvenient to carry any equipment.At present, more for the research method of target passive type location, be substantially divided into following three classes:

The first, the method based on non-radio signal framing: this method comprises the localization methods such as optical video, infrared sensor, at present in military and security fields application application to some extent.With the method based on radio signal, the method can not be at the outdoor environment of visual line of sight or be full of in the building of dense smoke and use.In addition, non-radio signal also can be because of the restriction of monitor area, and is not suitable for the location of moving target.

The second, counts localization method based on RSS fixed link: this method and the 3rd class all belong to radio signal localization method.Its main thought is first in the Fresnel region of single-link, to collect the diffracted signal intensity of target when diverse location, forms the data map of RSS.Next sets up positioning unit, by the RSS data in positioning unit and the data map comparison of previously having set up, estimates the position of target.Deployment region is covered and just can obtain the position of target by these unit.Because RSS data are easily subject to such environmental effects, a large amount of positioning units are deployed in the different region of environment and obviously for positioning precision, can produce a very large impact, and meanwhile, the location of moving target needs RSS data acquisition frequently.Therefore, this locator meams is applicable to the detection of static object under long-term fixed scene more, and is not suitable for the Moving objects location of interim scene.

The third, based on RSS on-fixed number of links localization method: to count localization method based on RSS fixed link different, the main thought of this localization method is that a large amount of positioning equipments is deployed to a kind of topological structure, then collect multilink scattering or diffraction information from equipment to another equipment, be conventionally embodied in RSS value different.Finally, utilize these multilink information to use different algorithms to go to realize location.Yet moving target can cause for multilink more and exert an influence, this not only can affect positioning precision, also can increase the time cost of location.Therefore this locator meams is not suitable for the situation of moving target or the less equipment of demand equally.

The 4th kind: based on Doppler shift localization method: Doppler shift is mainly used in military use and gesture identification field at present, main and arrival direction (the Direction of Arriva of this localization method, DOA) or time of arrival poor (Time Difference of Arriva, TDOA) method combines, for the location of high-speed moving object, for example, locate aircraft.With the object of the former combination be direction finding, be mainly the Doppler shift that utilizes relative motion between radar and aircraft to form, the impact according to target moving direction on Doppler shift, judges the direction of target.The object of being combined with the latter is range finding, is mainly the phase differential (or signal be transmitted into the mistiming of reception) of signal between radar different antennae that obtains moving target reflection, extrapolates the distance between aircraft and radar.Yet such localization method is not also suitable for the slower-velocity target location such as human body.First, the Doppler shift that the high-speed moving objects such as aircraft can cause is wider, and low speed moving target frequency swing is little, and detection difficulty is larger.Secondly, obtain the information such as phase differential higher for the cost requirement of hardware device, existing radar equipment is also faced with that power is high, volume large, high in cost of production problem, therefore existing radar fix method be not suitable for the location of low speed moving target in wireless network.In the existing gesture identification application based on Doppler shift, for the also expansion completely of relevant discussion of Moving objects location.

To sum up, existing passive type localization method can not well be applied in the scene of moving target passive type location, especially for the location of slower-velocity target, positioning precision can not well guarantee, therefore, study a kind of low speed moving target that is applicable to, the passive type localization method that positioning precision is high, communication overhead is little is necessary.

Summary of the invention

For the defect existing in above-mentioned prior art or deficiency, the object of the invention is to, a kind of passive type Moving objects location method (vehicle economy IL algorithm) based on Doppler shift is provided, the method can be located the location that completes single moving target in scene at passive type, use simultaneously less positioning equipment and with cost positioning time.

In order to realize above-mentioned task, the present invention adopts following technical scheme to be achieved:

A passive type Moving objects location method based on Doppler shift, specifically according to following steps, carry out:

Step 1, scene setting:

Step S11: arrange in a unscreened region to be measured, be stationary object in region to be measured except localizing objects.Region to be measured is comprised of a plurality of foursquare positioning units, in each positioning unit, be provided with the beacon of three known location, in the horizontal direction, every two adjacent positioning units have a beacon to share, and do not share beacon between the positioning unit of in the vertical direction; Three beacons in each positioning unit are designated as beacon X, beacon A, beacon Y successively, and three beacon spacing d are equal, and each beacon contains individual directional antenna, N represents number of sub-channels;

The positioning step of each positioning unit in region to be measured is identical, and the beacon in the positioning unit that the beacon in each positioning unit is adjacent is operated in different frequency or is operated in not in the same time; Following steps are the positioning step of single positioning unit;

Step 2, the generation of positioning signal

Step S21: all beacons in region to be measured are all based on FMT host-host protocol transmitted signal; Each beacon periodicity in this positioning unit produces one group of fixing symbol; Every class symbol is carried out to IFFT and be transformed to one group of N modulation symbol altogether, what IFFT converted is specifically calculated as follows shown in formula:

$x_n=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}{X}_k{e}^{i\frac{2\mathrm{\π}}{N}\mathrm{kn}},n=0,...,N-1$

In formula:

N represents number of sub-channels;

K represents sequence number;

N represents modulation symbol sequence number;

X _krepresent modulation bit in k sub-channels;

X _nrepresent that FMT signal is at time domain modulation symbol;

Step S22: each beacon is by the every group of x producing _nall to positioning unit, send in the following manner: the corresponding sub-channels of each modulation symbol, from every group of x _nsubchannel segmentation between two successively corresponding to the 0th to N-1 modulation symbol, obtain altogether section, sends by a directional antenna every section, uses altogether individual directional antenna;

Step 3, positioning signal reception is determined with orientation angle:

Step S31: three beacons receive signal in real time, and the time as shown in Equation 2 of only receiving with interior signal, if received signal, preserve execution step S32; Otherwise, for the subchannel not receiving, the respective sub-channel that in step S22, each beacon sends is compensated to and is received in signal, and perform step S32;

$T_k=\frac{{2l}_k}{c}$

In formula:

T _kthe time of reception that represents every sub-channels, unit: second;

L _krepresent the maximum distance that k sub-channels can reach in a positioning unit, unit: rice;

C represents the light velocity;

Step S32: when the signal of each beacon preservation reaches two groups, this beacon carries out 2FFT conversion by following formula to the signal receiving:

$X_k=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}\mathrm{kn}}(1+e^{-\mathrm{i\πk}}),k=0,...,N-1$

In formula:

N represents number of sub-channels;

K represents sequence number;

N represents modulation symbol sequence number;

X _krepresent modulation bit in k sub-channels;

X _nrepresent that FMT signal is at time domain modulation symbol;

Step S33: three beacons detect respectively Doppler shift, and preserve the subchannel sequence number that Doppler shift occurs; Otherwise three all do not detect Doppler shift and think and now do not have target, and perform step S32;

Step 4, the subchannel sequence number of preserving according to three beacons, determines the angle information of the directional antenna that beacon is corresponding, thereby determines the position of moving target.

Because the transmit direction of each directional antenna in beacon is fixed, so the angle information of directional antenna corresponding to subchannel is known.Therefore, the present invention locates moving target with the angle information of directional antenna.

Further, three beacon spacing d in described step 1 get 1～4 meter.

Further, the number of sub-channels N in described step 1 is 2 ⁿ, n is 4,5 or 6.

Further, in described step 1, under the polar coordinate system of each positioning unit, the direction scope that the directional antenna for this positioning unit in beacon X covers is 0 to arrive beacon A is 0 to π for institute's coverage direction scope of the directional antenna of this positioning unit, and beacon Y for the direction institute coverage of the directional antenna of this positioning unit is to π.

Further, the concrete steps of the beacon co-located of described step 4 are as follows:

Step S41: according to the subchannel sequence number of three beacons preservations, determine the angle information of the directional antenna that beacon is corresponding, be specifically divided into following several situation moving target is positioned;

The 1st kind: when obtaining α, β, according to following formula, obtain moving target position information:

$a=d\×\frac{\sin \mathrm{\α}}{\sin (\mathrm{\β}-\mathrm{\α})}$

In formula:

A represents beacon A and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

α represents the angle of the directional antenna that the subchannel sequence number of beacon X preservation is corresponding;

β represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

The coordinate of moving target is:

$\left\{\begin{array}{c}{x}_T=a\cos \mathrm{\β}\\ y_T=a\sin \mathrm{\β}\end{array}\right.$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

The 2nd kind: when obtaining β, γ, according to following formula, obtain moving target position information:

$a=\frac{d\sin \mathrm{\γ}}{\sin (\mathrm{\γ}-\mathrm{\β})}$

In formula:

A represents beacon A and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

β represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

γ represents the angle of the directional antenna that the subchannel sequence number of beacon Y preservation is corresponding;

The transverse axis coordinate of moving target is:

$\left\{\begin{array}{c}{x}_T=a\cos \mathrm{\β}\\ y_T=a\sin \mathrm{\β}\end{array}\right.$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

The 3rd kind: when obtaining α, γ or α, β, γ, according to following formula, obtain moving target position information:

$b=2d\×\frac{\sin \mathrm{\α}}{\sin (\mathrm{\γ}-\mathrm{\α})}$

In formula:

B represents beacon X and the distance that moving target detected, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

α represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

γ represents the angle of the directional antenna that the subchannel sequence number of beacon Y preservation is corresponding;

The transverse axis coordinate of moving target is:

$\left\{\begin{array}{c}{x}_T=b\sin \mathrm{\α}\\ y_T=d-b\cos \mathrm{\α}\end{array}\right.$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

(x _t, y _t) be the position coordinates of moving target.

Compared with prior art, useful technique effect of the present invention is as follows:

The present invention can be only according to the mobile impact of the Doppler on beacon transmission frequency of target (human body), determine that target is with respect to for three beacon directions, thereby complete the passive type location for target, the method has lower communication overhead, has improved the effect for mobile passive type target localization simultaneously.From practical application angle, the passive type localization method of research based on Doppler shift more has realistic meaning, specific as follows:

(1) method of the present invention only needs three beacons just can position single goal in positioning unit, the size of positioning unit can not be limited to the RSS rate of change of classic method, be that required number of beacons is compared minimizing to some extent with tradition, broken through the positioning strategy of passive type localization method based on RSS in traditional sense.

(2) method of the present invention, except not needing artificial pre-deployment, does not need priori, does not need manually to learn in advance scene information and obtains beyond RSS fingerprint, has lower communication overhead.

(3) the present invention is the moving target passive type localization method based on wireless network, realized the detection of low speed moving target Doppler shift in wireless network broadband signal, and then realize moving target passive type location, improved the positioning precision of moving target simultaneously.

(4) method of the present invention is good to the dynamic adaptable of environment, therefore can be good at adapting to the dynamic change of application scenarios, and this method has certain versatility.

(5) through experiment, the present invention compares classic method and has less deployed with devices density and less positioning and communicating expense when not reducing positioning precision.

Accompanying drawing explanation

Fig. 1 is a passive type positioning unit.

Fig. 2 be method of the present invention in the scene arranging to single positioning unit in the process flow diagram of Moving objects location.

Fig. 3 is the transfer process figure of FMT transmission technology.

Fig. 4 is that beacon receiving end carries out one times of FFT conversion and carries out two times of FFT conversion, for the impact of subchannel.

Fig. 5 is the subchannel of the FMT relation on frequency domain, and wherein, dark part is for carrying out after two times of FFT, the subchannel that receiving equipment can detect.

Fig. 6 is target moving direction and the angular relationship example that produces Doppler shift.

Fig. 7 obtains the example of locating after three beacon angle informations.

Fig. 8 is the field pattern example of directional antenna of the present invention in rectangular coordinate system.

Fig. 9 is the deployment way of DEIL localization method of the present invention.

Figure 10 is three kinds of position fixing processs (coordinate unit rice) of DEIL localization method of the present invention.

Figure 11 is DEIL localization method of the present invention location 1000 target localization examples (coordinate unit rice).

Figure 12 is that single beacon different antennae quantity is for the impact of positioning precision in the length of side is the square DEIL unit of 4 meters.

Figure 13 is to be 16 o'clock in single beacon antenna quantity, and the size of unit (unit length of side length) is for the impact of positioning precision.

Figure 14 is the comparison with passive type mid-point (intersection point) localization method positioning precision in 4 meters of unit of the identical length of side.

Figure 15 is that in DEIL method of the present invention, deployment density and mid point (intersection point) localization method are disposed the ratio increasing along with line number and columns.

Below in conjunction with drawings and Examples, particular content of the present invention is described in more detail.

Embodiment

For a positioning unit shown in Fig. 1, use passive type location, positioning strategy of the present invention is described.In this positioning unit, iff knowing the angle information of single beacon to target, cannot navigate to target location.Consider distance the having relatively high expectations for equipment that obtains beacon, therefore adopt single beacon localizing objects use equipment to have higher cost and larger volume, in reality, also need to seek other and solve thinking.The spacing of considering each beacon when beacon is disposed is known, and we can adopt multi-beacon to position target.In general, the angle information that obtains two beacons can position target, yet, be not that all beacons can obtain angle information, therefore we,, according to vertical line character, adopt three beacons to position as a positioning unit, can obtain enough locating information like this.But, this locator meams based on radar thought will bring hardware cost significantly to increase for Wireless Telecom Equipment, and therefore, the present invention improves existing Radio Transmission Technology, utilize the constraint condition of this constant of beacon spacing and angle to locate, reduce the hsrdware requirements of location.

Passive type Moving objects location method based on Doppler shift of the present invention comprises: angle is obtained stage, co-located stage (as Fig. 2).First stage obtains the direction of localizing objects for the beacon of locating.Subordinate phase, user utilizes the angle information of each directional antenna in a plurality of beacons to realize the location of moving target.Angle is obtained the stage, need to complete the detection of positioning signal generation, spatial sampling, positioning signal reception, Doppler shift and determine angle information according to the result of cumulative ring.First, beacon utilizes the doppler information of the low speed moving target of existing communication transmission technology realization to detect, and the generation of positioning signal is the design details that need to consider with the key factor receiving as the design of DEL method.Secondly, spatial sampling is also the aspect being even more important in DEL localization method.Specifically, we cover some directions these signals with identical angle intervals successively at imagination, and the space that completes 180 ° covers, the ability of final implementation space sampling.Because beacon is treated as a transmitter and receiving equipment simultaneously, when target is in a certain position during to beacon direction motion (or produce the party move upward component), the signal that beacon covers in this direction will produce Doppler shift and reflex to beacon direction by target, and we can detect Doppler shift.Consider that the respective angles that each signal covers knows in advance, beacon only need to know that the signal in which direction produces Doppler shift and learns that target is with respect to the direction of this beacon, thereby obtains angle information.In the co-located stage, user need to collect the angle information that a plurality of beacons obtain, and calculates the relative position of target according to the angle information of these beacons, the absolute position of finally extrapolating localizing objects according to the absolute coordinates of these beacons.DEL method is disposed beacon in the condition compared with small configuration density, guarantees the beacon realization location of containing angle information simultaneously.

In positioning signal, produce the stage, the present invention utilizes existing FMT host-host protocol, echo with the signal reception stage, the signal that localizing objects (virtual transmitter) is reflected back to beacon carries out two times of FFT, thereby realize the frequency interval of subchannel, the channel disturbance problem of further avoiding Doppler shift to produce.

In positioning signal, send to receive with orientation angle and determine the stage, use the sampling of directional antenna implementation space, thereby complete cutting apart for the location in space, receiving unit for signal, consider the efficiency of efficiency location and for the problem of multipath effect, in the process of obtaining in beacon angle, exist subchannel by antenna transmission, not to be reflected back the situation of beacon, beacon affects follow-up work and carries out because receiving enough subchannel information.Consider that receiving equipment and transmitter are all present in this beacon, the ten-four of each sub-channel transmission.Therefore, for unreflected signal, can adopt existing method to carry out corresponding channel compensation.Before beacon compensation, need to carry out subchannel estimation, judge the condition of channel compensation, FMT subchannel frequency band independently feature brings the facility that detects and estimate.Next, can Time Created window carry out threshold determination, in the situation that deployment region size is known, can determine and estimate and compensation condition according to maximum duration window Time Created that estimates signal reflex, make that ensuing location is working properly to complete.Effect due to two times of FFT, can only capture even number subchannel and it is completed to Doppler shift and detect, after detection completes according to different subchannel antennas to the mapping table of spatial sampling to being converted to corresponding angle information, thereby complete the button-up operations of location.

At beacon, combine estimation positioning stage, according to the angle information from each beacon, be combined in the beacon pitch information of previously known, just can combine the position that target is oriented in estimation.

Lower mask body provides implementation step and the details of the method in the above-mentioned stage.

Scene setting:

As shown in Figure 9, in a unscreened region to be measured, arrange, in region to be measured, except localizing objects, be stationary object.Region to be measured is comprised of a plurality of foursquare positioning units, in each positioning unit, be provided with the beacon of three known location, in the horizontal direction, every two adjacent positioning units have a beacon to share, and do not share beacon between the positioning unit of in the vertical direction; Three beacons of (beacon is for realizing the equipment of wireless communication) each positioning unit are designated as beacon X, beacon A, beacon Y successively, and three beacon spacing d equate (d gets 1～4 meter), and each beacon contains individual directional antenna, N represents that number of sub-channels (generally gets 2 ⁿ, n is 4,5,6), under the polar coordinate system of each positioning unit, the direction scope that the directional antenna for this positioning unit in beacon X covers is 0 to arrive beacon A is 0 to π for institute's coverage direction scope of the directional antenna of this positioning unit, and beacon Y for the direction institute coverage of the directional antenna of this positioning unit is to π.

In the present invention, utilize the directional antenna in the beacon of location aware to send wireless signal in corresponding positioning unit, in the situation that target is not moved, target meeting reflected signal (as virtual transmitter), signal can be received (being equivalent to receiver) by beacon again, but because target is that movement or limbs move, can make wireless signal produce Doppler shift, beacon can detect many strangles frequency displacement to general, therefore moving realization of Doppler shift, the location of single positioning unit being detected based on beacon.The positioning step of each positioning unit in region to be measured is identical, and the beacon in the positioning unit that the beacon in each positioning unit is adjacent is operated in different frequency or is operated in not in the same time.

Positioning signal produces:

Traditional Radio Transmission Technology is not enough to human body or the kinetic less Doppler shift of animal body.For human body walking motion, standing state accounts for 60% in the cycle of human body walking, and the swing that human motion is accompanied by limbs is in addition higher than human motion speed.Therefore, human motion causes that the speed of Doppler shift is slightly larger than the actual speed of travel of human body.The speed of travel of considering the most comfortable is 1.3m/s, and giving tacit consent to the speed that human motion causes Doppler shift is herein 1.5m/s.From formula (1), when beacon emissions frequency is 5GHz, human motion causes that maximum doppler frequency is 50Hz (θ=0 °), and the Doppler shift causing under this speed is relevant to θ.The kinetic Doppler shift of human body is much smaller than the transmission bandwidth of wireless network.Therefore, beacon need to be converted to wireless signal narrow band signal to complete the detection of less Doppler shift.

The major function of the beacon of locating for passive type is network consisting communication facilities, so communication framework is the element of equipment.Passive type localization method based on Doppler shift needs be a kind of can be for the narrow band signal of location, because it is a kind of locator meams based on echo (reflection) principle, this has just proposed challenge to traditional communication facilities: increase new hardware architecture or existing communication framework is improved.In order to solve this difficult problem, the present invention proposes a kind of locator meams based on existing communication FMT transmission technology, the method only need to be carried out low-cost improvement for positioning equipment just can realize the localization method based on Doppler shift, improve the channel disturbance between narrowband subchannels simultaneously, the frequency displacement information equipment (being beacon) that is more easily positioned is detected.

DEIL algorithm of the present invention is a kind of technology based on FMT (filtered multi-tone) transmission plan, Fig. 3 is the transfer process figure of FMT, in transmitting apparatus, send symbol after IFFT conversion after parallel-serial conversion the subcarrier with one group of equifrequent interval carry out uniform frequency spectrum shift, at transmitting terminal, send out; At receiving end, with corresponding subcarrier, from the signal receiving, demodulate the signal of modulation, then go here and there and change, then carry out FFT conversion, it should be noted that transmitting terminal and receiving end are same beacon in DEIL.FMT is a kind of land clustered wireless system institute accepted standard of being formulated by ETSI (ETST).The different FMT of being of this method and OFDM maximum are the N sub-channels for independently separating on frequency band by bandwidth division, thereby the phenomenon of subchannel aliasing does not occur, the respective center frequency of each subchannel be fk (k=0,1,2 ..., N-1).Speed in target travel is V, and target travel direction and target are θ to the angle of beacon, and the centre frequency of subchannel is f _0ktime, the Doppler shift of generation is Δ f _kfor:

${\mathrm{\Δf}}_k=\frac{2V\cos \left(\mathrm{\θ}\right)}{c}{f}_{0k}---\left(1\right)$

Here it is frequency shift amount that every sub-channels need to detect.The interference of channel will be brought like this, while is due to the broader bandwidth of channel, and the frequency shift amount producing is generally less, therefore the direct detection of using FMT transmission mode and being unfavorable for Doppler shift, based on this, the present invention proposes a kind of improvement for existing IFFT, FFT, at transmitting terminal, sends identical symbol, and carry out IFFT conversion to sending symbol, shown in being specifically calculated as follows:

$x_n=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}{X}_k{e}^{i\frac{2\mathrm{\π}}{N}\mathrm{kn}},n=0,...,N-1---\left(2\right)$

In formula:

N represents number of sub-channels;

K represents sequence number;

N represents modulation symbol sequence number;

X _krepresent modulation bit in k sub-channels;

X _nrepresent modulation symbol;

In traditional mode, carry out FFT as follows:

$X_k=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{N}\mathrm{kn}}k=0,...,N-1---\left(3\right)$

The improvement that we do is at receiving end, to carry out the FFT variation of two times, and receiving end carries out as down conversion:

$X_k=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}\mathrm{kn}}+\underset{n=N}{\overset{2N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}\mathrm{kn}},k=0,...,2N-1---\left(4\right)$

The symbol of considering transmitting terminal transmission is identical, i.e. x _n=x _n+N, so this equation can be transformed to:

$X_k=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}\mathrm{kn}}+\underset{n=1}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}k(n+N)},k=0,...,N-1---\left(5\right)$

After arranging:

$X_k=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}\mathrm{kn}}(1+e^{-\mathrm{i\πk}}),k=0,...,N-1---\left(6\right)$

We can find, when subchannel is odd number, the receiving end of beacon is this subchannel, i.e. (1+e to be detected ^{-i π k})=0;

When subchannel is even number, receiving end is the subchannel that two times of amplitudes can be detected, i.e. (1+e ^{-i π k})=2.Work as k=2m, equation can arrange the form into FFT:

$X_{2m}=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}2\mathrm{mn}},X_{2m+1}=\mathrm{0,2}m=0,...,N-1---\left(7\right)$

As Fig. 4, for system is carried out one times of FFT and two times of FFT conversion for the difference of subchannel.Specifically, as Fig. 5, for the direct relation of FMT subchannel on frequency domain is completely separated (they is the subchannel of the FMT of transmitting terminal transmission), on frequency domain, show to only have blue subchannel to catch receiving end.Through such conversion, can bundle channel conversion be just the narrow band signal that has interval, not only met the requirement of Doppler shift for narrow band signal, further reduced the interference of Doppler shift for adjacent channel simultaneously.

Positioning signal sends to receive with orientation angle to be determined:

The information exchange of these subchannels is crossed directional antenna (beam angle is 10 ° conventionally), and the example area realizing as shown in Figure 5 covers, and directional antenna quantity used is the quantity that wherein N is subchannel.Because the centre frequency of each beacon emissions signal is different, therefore there is not the mutual disturbed condition of beacon.The spacing of directional antenna coverage direction is thereby realize the covering for region.

Because every two sub-channels of signal all can a direction radiation, the radiation direction that is subchannel is not identical, this just produces three problems: first, have the subchannel of localizing objects direction in the subchannel reflecting, but not all subchannel all can reflect information; Secondly, subchannel needs the thresholding of a reception, determines not navigate in unit exterior domain; Finally, also can have the problem of multipath effect, signal arrives mobile target by multipath reflection and produces Doppler shift.Based on this, need to carry out time window judgement to signal, concrete judgement is as follows:

Signal reception time judgement, this shows that I am for this time locating and receive only in time T _kwithin signal, do like this and can also further improve location efficiency:

$T_k=\frac{{2l}_k}{c}---\left(8\right)$

In formula:

T _kthe time of reception that represents every sub-channels, unit: second;

L _krepresent the maximum distance that k sub-channels can reach in unit, unit: rice;

C represents the light velocity;

So just realized the spatial sampling for signal.Next for signal, carry out estimation and the compensation of subchannel, because beacon is being born the effect of transmitter and receiving equipment, therefore can realize very easily subchannel and estimate and compensation, next carry out the FFT conversion of two times, and the detection of Doppler shift.The direction that Doppler shift detected is exactly the direction of target, finally, because the angle of coverage of orientation direction is that equipment just completes when disposing, therefore can obtain angle information α, β, γ by three beacons (being expressed as from left to right X, A, Y) from unit, for the location of phase III provides available parameter.

Here it should be noted that, two parameters just can estimate the position of target, but from formula 1, exist a kind of situation target travel direction therefore cannot produce Doppler shift with beacon to target direction vertical (as Fig. 6), therefore cannot locate.But according to vertical line character, cross and a bit have and only have straight line vertical with known straight line.Therefore, adopt three beacons to obtain two parameters to I haven't seen you for ages, can realize location.

Beacon co-located:

Complete after angle determines, beacon forms triangle with localizing objects, and when known quantity is two angles and the length of side (spacing of beacon), we can obtain according to sine the length on other both sides, thereby realization is located:

$\frac{d}{\sin [\mathrm{\π}-\mathrm{\α}-(\mathrm{\π}-\mathrm{\β})]}=\frac{a}{\sin \left(\mathrm{\α}\right)}=\frac{b}{\sin (\mathrm{\π}-\mathrm{\β})}---\left(9\right)$

If obtain angle information in the concrete process of implementing, only there are two, directly adopt the mode of sine to go to realize location, if obtain three angle parameters on last stage, consideration for positioning precision, all adopt the angle information of beacon X and beacon Y to position, if Fig. 7 is example, detailed process is as follows:

1,, when obtaining the angle value of α, β, according to following formula, obtain localizing objects:

$a=d\×\frac{\sin \mathrm{\α}}{\sin (\mathrm{\β}-\mathrm{\α})}---\left(10\right)$

In formula:

A represents beacon A and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

α represents the angle of the directional antenna that the subchannel sequence number of beacon X preservation is corresponding;

β represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

The transverse axis coordinate of localizing objects is:

$\left\{\begin{array}{c}{x}_T=a\cos \mathrm{\β}\\ y_T=a\sin \mathrm{\β}\end{array}\right.---\left(11\right)$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

2,, when obtaining the angle value of β, γ, according to following formula, obtain localizing objects:

$a=\frac{d\sin \mathrm{\γ}}{\sin (\mathrm{\γ}-\mathrm{\β})}---\left(12\right)$

In formula:

A represents beacon A and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

β represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

γ represents the angle of the directional antenna that the subchannel sequence number of beacon Y preservation is corresponding;

The transverse axis coordinate of localizing objects is:

$\left\{\begin{array}{c}{x}_T=a\cos \mathrm{\β}\\ y_T=a\sin \mathrm{\β}\end{array}\right.---\left(13\right)$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

3,, when obtaining the angle of α, γ or α, β, tri-angles of γ, according to following formula, obtain

Localizing objects:

$b=2d\×\frac{\sin \mathrm{\α}}{\sin (\mathrm{\γ}-\mathrm{\α})}---\left(14\right)$

In formula:

B represents beacon X and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

α represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

γ represents the angle of the directional antenna that the subchannel sequence number of beacon Y preservation is corresponding;

The transverse axis coordinate of localizing objects is:

$\left\{\begin{array}{c}{x}_T=b\sin \mathrm{\α}\\ y_T=d-b\cos \mathrm{\α}\end{array}\right.---\left(15\right)$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

(x _t, y _t) be exactly the position coordinates of passive type localizing objects.

Below provide specific embodiments of the invention, it should be noted that the present invention is not limited to following specific embodiment, all equivalents of doing on present techniques scheme basis all fall into protection scope of the present invention.

Beacon equipment with 10GHz in following embodiment completes experiment test in emulation, and 1000 data have been collected in test.

Embodiment:

In this embodiment, adopting the frequency of operation of beacon is 10Ghz, carries out positioning experiment 1000 times.

The present embodiment has provided a kind of passive type localization method based on Doppler shift, and design parameter is as follows:

The scene setting of step 1: one without any the communication environments blocking in, except localizing objects, be all stationary object in environment.Environment is comprised of some square positioning units, three beacons of known location form a unit, three beacons in unit are designated as respectively beacon X, beacon A, beacon Y from left to right, three beacon spacing equate the rice for d=2, FMT adopts N=32 to represent subchannel number, channel width is 1MHz, the narrow band signal that subchannel is 31.25kHz, and each beacon contains directional antenna, the spacing of these directional antenna coverage directions is wherein beacon X is 0 to arrive for the direction scope of the directional antenna of this cell location beacon A is 0 to π for the direction scope of the directional antenna of this cell location, and beacon Y for the direction scope of the directional antenna of this cell location is to π, the beacon of location aware sends wireless signal by directional antenna to environment in unit, in the situation that target is not moved, localizing objects meeting reflected signal (as virtual transmitter), signal can be received (being equivalent to receiver) by beacon again, but because target is mobile or limbs moves, can make wireless signal produce Doppler shift, more than beacon can detect, to general, strangle frequency displacement; Following steps are the positioning step of a unit, and the positioning step of each unit is identical, and the beacon in positioning unit is operated on different frequency with the beacon in 8 adjacent positioning units around, and the size of positioning unit is the region of 4 meters * 4 meters.

The positioning signal of step 3 sends to receive with orientation angle to be determined: in each positioning unit, and the maximum distance l that k sub-channels can reach in unit _kvalue be:

For 4.0784 meters 4 meters, 4.0784 meters of 4.3296 meters of 4.8108 meters of 5.6569 meters of 4.81084.3296 rice of beacon X{4 rice }

For 2.1648 meters 2.4054 meters 2.8284 meters 3.5999 meters 4.3296 meters 4.0784 meters 4 meters 4.0784 meters 4.3296 meters 3.5999 meters 2.8284 meters 2.4054 meters 2.1648 meters 2.0392 meters, beacon A{2.0392 rice }

For 4.0784 meters 4 meters, 4.0784 meters of 4.3296 meters of 4.8108 meters of 5.6569 meters of 4.81084.3296 rice of beacon Y{4 rice }.

Locating effect:

The present invention carries out the example of 1000 location as Figure 11, in table 1, represents the positioning precision that use DEIL method of the present invention positions, and by table 1, is found out, the positioning result of positioning error within the scope of 0.5 meter can arrive 75.2% of positioning result.

Table 1

?	0.5m	1m	1.5m	2m	2.5m
						DEIL(％)	75.2	91.1	95.6	96.5	97.3

By Figure 12, Figure 13, found out, the difference of antenna amount and the size of cellar area can exert an influence for the precision of location.We have contrasted the positioning precision (Figure 14) for mid point and two kinds of localization methods of intersection point and the DEIL of passive type Moving objects location in the situation that of identical location area, can see that the positioning precision of DEIL is very high.

For deployment density, in identical deployed with devices interval situation, as shown in figure 15, along with the increase of columns, the deployment density maximum of DEIL only reaches 50% of mid point and intersection point localization method deployment density, so deployment density is lower.

In addition, table 2 shows that middle independent positioning method is relevant with the number of deployment facility with the communication overhead of intersection point localization method, so power consumption increases along with disposing the increase of scale, and therefore DEIL can't change the communication overhead of single location.

Table 2

The localization method of contrast has comprised middle independent positioning method, intersection point location algorithm.List of references: D.Zhang, J.Ma, Q.Chen, and L.M.Ni.An rf-based system for tracking transceiver-free objects.In IEEE PerCom, pages135 – 144,2007.

Claims (5)

1. the passive type Moving objects location method based on Doppler shift, is characterized in that, comprises the following steps:

Step 1, scene setting:

Step S11: arrange in a unscreened region to be measured, be stationary object in region to be measured except localizing objects; Region to be measured is comprised of a plurality of foursquare positioning units, in each positioning unit, be provided with the beacon of three known location, in the horizontal direction, every two adjacent positioning units have a beacon to share, and do not share beacon between the positioning unit of in the vertical direction; Three beacons in each positioning unit are designated as beacon X, beacon A, beacon Y successively, and three beacon spacing d are equal, and each beacon contains individual directional antenna, N represents number of sub-channels;

The positioning step of each positioning unit in region to be measured is identical, and the beacon in the positioning unit that the beacon in each positioning unit is adjacent is operated in different frequency or is operated in not in the same time; Following steps are the positioning step of single positioning unit;

Step 2, the generation of positioning signal:

Step S21: all beacons in region to be measured are all based on FMT host-host protocol transmitted signal; Each beacon periodicity in this positioning unit produces one group of fixing symbol; Every class symbol is carried out to IFFT and be transformed to one group of N modulation symbol altogether, what IFFT converted is specifically calculated as follows shown in formula:

$x_n=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}{X}_k{e}^{i\frac{2\mathrm{\π}}{N}\mathrm{kn}},n=0,...,N-1$

In formula:

N represents number of sub-channels;

K represents sequence number;

N represents modulation symbol sequence number;

X _krepresent modulation bit in k sub-channels;

X _nrepresent that FMT signal is at time domain modulation symbol;

Step S22: each beacon is by the every group of x producing _nall to positioning unit, send in the following manner: the corresponding sub-channels of each modulation symbol, from every group of x _nsubchannel segmentation between two successively corresponding to the 0th to N-1 modulation symbol, obtain altogether section, sends by a directional antenna every section, uses altogether individual directional antenna;

Step 3, positioning signal reception is determined with orientation angle:

Step S31: three beacons receive signal in real time, and the time as shown in Equation 2 of only receiving with interior signal, if received signal, preserve execution step S32; Otherwise, for the subchannel not receiving, the respective sub-channel that in step S22, each beacon sends is compensated to and is received in signal, and perform step S32;

$T_k=\frac{{2l}_k}{c}$

In formula:

T _kthe time of reception that represents every sub-channels, unit: second;

L _krepresent the maximum distance that k sub-channels can reach in a positioning unit, unit: rice;

C represents the light velocity;

Step S32: when the signal of each beacon preservation reaches two groups, this beacon carries out 2FFT conversion by following formula to the signal receiving:

$X_k=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n{e}^{-i\frac{2\mathrm{\π}}{2N}\mathrm{kn}}(1+e^{-\mathrm{i\πk}}),k=0,...,N-1$

In formula:

N represents number of sub-channels;

K represents sequence number;

N represents modulation symbol sequence number;

X _krepresent modulation bit in k sub-channels;

X _nrepresent that FMT signal is at time domain modulation symbol;

Step S33: three beacons detect respectively Doppler shift, and preserve the subchannel sequence number that Doppler shift occurs; Otherwise three all do not detect Doppler shift and think and now do not have target, and perform step S32;

Step 4, the subchannel sequence number of preserving according to three beacons, determines the angle information of the directional antenna that beacon is corresponding, thereby determines the position of moving target.

2. the passive type Moving objects location method based on Doppler shift as claimed in claim 1, is characterized in that, three beacon spacing d in described step 1 get 1～4 meter.

3. the passive type Moving objects location method based on Doppler shift as claimed in claim 1, is characterized in that, the number of sub-channels N in described step 1 is 2 ⁿ, n is 4,5 or 6.

4. the passive type Moving objects location method based on Doppler shift as claimed in claim 1, it is characterized in that, in described step 1, under the polar coordinate system of each positioning unit, the direction scope that the directional antenna for this positioning unit in beacon X covers is 0 to arrive beacon A is 0 to π for institute's coverage direction scope of the directional antenna of this positioning unit, and beacon Y for the direction institute coverage of the directional antenna of this positioning unit is to π.

5. the passive type Moving objects location method based on Doppler shift as claimed in claim 1, is characterized in that, the concrete steps of the beacon co-located of described step 4 are as follows:

Step S41: according to the subchannel sequence number of three beacons preservations, determine the angle information of the directional antenna that beacon is corresponding, be specifically divided into following several situation moving target is positioned;

The 1st kind: when obtaining α, β, according to following formula, obtain moving target position information:

$a=d\×\frac{\sin \mathrm{\α}}{\sin (\mathrm{\β}-\mathrm{\α})}$

In formula:

A represents beacon A and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

α represents the angle of the directional antenna that the subchannel sequence number of beacon X preservation is corresponding;

β represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

The coordinate of moving target is:

$\left\{\begin{array}{c}{x}_T=a\cos \mathrm{\β}\\ y_T=a\sin \mathrm{\β}\end{array}\right.$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

The 2nd kind: when obtaining β, γ, according to following formula, obtain moving target position information:

$a=\frac{d\sin \mathrm{\γ}}{\sin (\mathrm{\γ}-\mathrm{\β})}$

In formula:

A represents beacon A and detects range-to-go, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

β represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

γ represents the angle of the directional antenna that the subchannel sequence number of beacon Y preservation is corresponding;

The transverse axis coordinate of moving target is:

$\left\{\begin{array}{c}{x}_T=a\cos \mathrm{\β}\\ y_T=a\sin \mathrm{\β}\end{array}\right.$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

The 3rd kind: when obtaining α, γ or α, β, γ, according to following formula, obtain moving target position information:

$b=2d\×\frac{\sin \mathrm{\α}}{\sin (\mathrm{\γ}-\mathrm{\α})}$

In formula:

B represents beacon X and the distance that moving target detected, unit: rice;

D represents the distance of any two neighbor beacon in positioning unit, unit: rice;

α represents the angle of the directional antenna that the subchannel sequence number of beacon A preservation is corresponding;

γ represents the angle of the directional antenna that the subchannel sequence number of beacon Y preservation is corresponding;

The transverse axis coordinate of moving target is:

$\left\{\begin{array}{c}{x}_T=b\sin \mathrm{\α}\\ y_T=d-b\cos \mathrm{\α}\end{array}\right.$

In formula:

X _thorizontal ordinate for moving target;

Y _tordinate for moving target;

(x _t, y _t) be the position coordinates of moving target.