CN102883360A - Method and system for wirelessly omnidirectionally and passively detecting user indoors - Google Patents

Abstract

The invention provides a method and system for wirelessly, omnidirectionally and passively detecting users indoors. The method comprises the following steps: extracting the to-be-detected position fingerprint (LF) from the physical layer information of the indoor wireless local area network; calculating the similarity of the LF and the preset position fingerprint; and judging whether users exist in the monitored area or not or further judging the situation of the position of the users according to the similarity of the LF and the preset position fingerprint. Because information is extracted from the physical layer and the statistical histogram of channel response is taken as the signal feature, the discrimination and robustness are improved, the users can be detected omnidirectionally.

Description

The method and system that a kind of indoor wireless passive user of omnidirectional detects

Technical field

The present invention relates to mobile and general fit calculation field, relate in particular to a kind of physical layer information of WLAN (wireless local area network) of utilizing as the method and system of the passive user's detection of the indoor wireless omnidirectional of location fingerprint.

Background technology

Universal and the application of Wireless Communication Equipment has promoted the Triple Fusion of general fit calculation, mobile computing and this calculating of people.In increasing environment, need equipment to detect user's situation on every side, such as the concerning security matters area monitoring, disaster emergency response etc.In addition, this passive user's detection mode also helps to provide the service based on customer location of different quality.For example, elevator door closes etc.And also have a lot of places, such as museum exhibit, then need user's detection range of omnidirectional.

Utilize radar or radio ultra wide band system based on the detection technique of reflection, the realization omnidirectional that can be similar to is detected, but owing to depending on special-purpose equipment, has hindered the promotion and application of these technology.And utilize the WLAN (wireless local area network) of generally disposing, can realize that passive user detects in the situation that need not additional hardware support.Main principle is that the movement of the human body impact on radio signal propagation in the interior space is associated, and judges by certain signal characteristic that detects receiving terminal whether the area to be monitored has the user to enter.

Present this detection method has mainly adopted the fluctuation of the received signal strength (Received Signal Strength Indicator, RSSI) in the MAC layer information as differentiating whether the user is arranged near the signal characteristic of receiver.Yet these work are unrealized omnidirectional coverage all, and, can not realize that identical user detect effect in all directions, detect so be suitable for the user of omnidirectional.

Summary of the invention

The invention provides the method and system that a kind of indoor wireless passive user of omnidirectional detects, realized that indoor being applicable to obtains the testing mechanism that identical user detects effect in all directions, described technical scheme is as follows:

The passive user's detection method of a kind of indoor wireless omnidirectional comprises:

From the indoor wireless local area network physical layer information, extract location fingerprint to be measured (LF);

Calculate described location fingerprint to be measured and the similarity of measuring in advance good location fingerprint;

Judge the situation that in the area to be monitored no user is arranged or further judge the user present position according to described similarity.

Further, describedly from the indoor wireless local area network physical layer information, extract location fingerprint to be measured, comprising:

Will be owing to the distance of user distance receiver be different with the orientation, and the variation in the radio signal propagation path that causes, convert the statistic histogram of channel frequency response (CFR) to, utilize described statistic histogram as described location fingerprint.

Further, with the amplitude histogram of the channel frequency response on a plurality of subcarriers as the location fingerprint of extracting from the indoor wireless local area network physical layer.

Further, each histogram component obtains by the channel frequency response amplitude of calculating a predefined time window.

Further, described location fingerprint when measuring in advance good location fingerprint and comprising the location fingerprint database set up in advance or no user.

Further, the described location fingerprint database of setting up in advance is:

The user is not when having the user in receiver has different distance and bearing angles and area to be monitored, and described receiver detects the feature of channel frequency response, the feature of described channel frequency response as location fingerprint, the database of foundation.

Further, described calculating location fingerprint to be measured and the similarity of measuring in advance good location fingerprint comprise:

The channel frequency response amplitude histogram vector of comparing for two calculates the land mobile distance of the channel frequency response amplitude histogram between described vectorial the corresponding K subcarrier;

With all K cumulative the summations as the similarity between two location fingerprint of land mobile distance;

Wherein, K is the integer greater than 1.

Further, the land mobile distance between two histograms of described calculating comprises:

According to two histogrammic positions to be compared and weight, calculate the land mobile distance between two histograms.

Further, judge according to described similarity and comprise the situation that in the area to be monitored no user is arranged or further judge the user present position:

The similarity of the location fingerprint when location fingerprint to be measured and described no user is during greater than the threshold value set, and judging in the current area to be monitored does not have the user;

The similarity of the location fingerprint when location fingerprint to be measured and described no user is during less than the threshold value set, and judging in the current area to be monitored has the user;

Perhaps:

Judge in the described database that the position corresponding with the highest location fingerprint of location fingerprint similarity to be measured is the current position of user;

Or the location fingerprint similarity when not having the user in location fingerprint to be measured and the described location fingerprint database is when the highest, and judging in the current area to be monitored does not have the user.

The passive user's detection system of a kind of indoor wireless omnidirectional comprises:

Transmitter and receiver, described transmitter and described receiver are by the mutual communication of WLAN (wireless local area network);

Described transmitter is used for wireless signal emission;

Described receiver is used for receiving the wireless signal of described transmitter emission, extracts location fingerprint to be measured from described signal; Calculate described location fingerprint to be measured and the similarity of measuring in advance good location fingerprint; Judge the situation that in the area to be monitored no user is arranged or further judge the user present position according to described similarity.

Embodiment provided by the invention by from the information extraction of indoor wireless local area network physical layer, utilizes the statistic histogram of channel response as signal characteristic, has improved discrimination and robustness, has realized that the user of omnidirectional detects.

Description of drawings

Fig. 1 is indoor wireless omnidirectional passive user's detection method flow chart that the embodiment of the invention provides.

Fig. 2 is the indoor wireless omnidirectional passive user's detection method flow chart based on threshold test that the embodiment of the invention provides.

Fig. 3 is indoor wireless omnidirectional passive user's detection system structural representation that the embodiment of the invention provides.

Embodiment

The present invention is described in further detail below in conjunction with drawings and Examples.Be understandable that, specific embodiment described herein only is used for explaining the present invention, but not limitation of the invention.

Embodiment 1

Fig. 1 is indoor wireless omnidirectional passive user's detection method flow chart that the embodiment of the invention provides.The method comprises:

Step 101: from the indoor wireless local area network physical layer information, extract location fingerprint LF feature to be measured;

Step 101 specifically comprises:

At monitor stages, the signal of the continuous receiver/transmitter emission of receiver, and extract signal characteristic, this signal characteristic can characterize the user at the different relative position of guarded region, this signal characteristic as location fingerprint information to be measured, is analyzed in the step below.

Specifically, with the user as a variable that affects wireless channel, the variation owing to the distance radio signal propagation paths that cause different from the orientation of user distance receiver, convert the statistic histogram of channel frequency response to, utilize statistic histogram as location fingerprint.Wherein, channel frequency response comprises amplitude response and phase response.

In typical indoor environment, the movement of human body produces certain impact to the propagation of interior space wireless signal, transmit and arrive receiving terminal via many propagation paths, every paths is to different time-delays, decay and the phase shift affects of transmitting, obtain the feature of certain signal of receiving terminal by detection, characterize the situation of area to be monitored customer location with these features, we call location fingerprint (Location Fingerprint, LF) feature to these features.

The method that embodiment provided by the invention adopts can be distinguished multipath signal, thereby can extract more meticulous signal characteristic.Distinguishing multipath signal can consider from time domain and frequency domain two aspects:

1. from the angle-resolved multipath of time domain:

Wireless channel is described as a time domain linear filter, is called channel impulse response (Channel Impulse Response, CIR), represent with function h (τ).

$h\left(\mathrm{\τ}\right)=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{a}_i\exp (-j{\mathrm{\θ}}_i)\mathrm{\δ}(\mathrm{\τ}-{\mathrm{\τ}}_i)$

A wherein _iThe amplitude fading that represents i bar multipath component; θ _iRepresent the phase deviation of i bar multipath component; τ _iThe time delay that represents i bar multipath component; N represents the multipath sum; δ (τ) represents impulse function.

2. from the angle-resolved multipath of frequency domain:

Wireless channel is described as channel frequency response (Channel Frequency Response, CFR), represents with function H (f):

H(f)=[H(f ₁),H(f ₂),...,H(f _K)]

Each H (f wherein _k) be a plural number, amplitude and the phase place at expression frequency f place.Therefore, channel frequency response comprises amplitude-frequency response and phase-frequency response two parts.The frequency selective fading phenomenon of CFR has embodied the variation of affected multipath component.

Because channel response is by the propagation path of wireless signal of having distinguished the multipath effect meticulous depiction, thereby this physical layer information detects the passive user of omnidirectional and brings very large performance boost space.

We characterize the amplitude-frequency response that adopts channel frequency response CFR the variation of propagation path, as the optimal way of the embodiment of the invention.Mainly consider for the following aspects:

⑴ to the anti-interference of environment dynamic: experiment showed, the user when diverse location, the spatial cross correlation between the CFR is lower, thereby so that CFR has higher space region calibration.And has higher correlation between the CFR that the different time user records when being in same relative position.So the structure of CFR has preferably time consistency, can resist the interference of environmental change at a distance.

⑵ the sensitiveness that signal characteristic is close concerning the user: the sensitiveness angle that changes from human influence's wireless channel, the fluctuation range of CFR is whole frequency domain.Usually only changing a part of propagation path during human motion, can equivalence be the normal value signal that covers whole frequency range on frequency domain.

⑶ CFR comprises amplitude-frequency response and phase-frequency response, and experiment shows, adopts phase-frequency response will alleviate phase noise, needs carefully calibration phase information; And the phase place of parton carrier wave is within a certain period of time approximate and evenly distributes, thereby has reduced the discrimination relevant with the position.Simultaneously, equally distributed phase place also causes being difficult to CFR is used traditional clustering method extraction feature.Therefore, adopt amplitude-frequency response more easily to realize.

Because the amplitude distribution of CFR is comparatively disperseed, utilize traditional clustering method to need the larger data amount, and need comparatively meticulous granularity of division, therefore, embodiments of the invention are the statistic histogram information of the amplitude distribution of the CFR location fingerprint as detection signal, are about to the amplitude histogram of the CFR on K the subcarrier as the physical layer attributes of extraction:

hist(||H(f)||)=[hist(||H(f ₁)||),hist(||H(f ₂)||)，...,hist(||H(f _K)||)]

Each histogram component hist (|| H (f _k) ||) can obtain by calculating a CFR amplitude in the predefined time window.

Therefore, the variation that the amplitude-frequency response of employing CFR characterizes propagation path has traditional huge advantage that RSSI did not have, so we can realize technical scheme by the amplitude-frequency response method of CFR.

Step 102: the similarity of calculating location fingerprint in described location fingerprint to be measured and the location fingerprint database of setting up in advance;

What the location fingerprint database of setting up in advance in the present embodiment represented is: the user is not when having the user in receiver has different distance and bearing angles and area to be monitored, described receiver detects the feature of channel frequency response, the feature of described channel frequency response as location fingerprint, the database of foundation.

Step 102 specifically comprises step 1021 ~ 1022:

For comparing the similarity of two CFR amplitude histogram vectors, at first to define two similarities between the histogram component, the embodiment of the invention has adopted land mobile distance (EMD, Earth Mover ' s Distance) to define two similarities between the histogram component.EMD is a kind of estimating between histogram or the probability distribution of weighing.

Step 1021: the channel frequency response amplitude histogram vector of comparing for two, calculates the land mobile distance of the channel frequency response amplitude histogram between described vectorial the corresponding K subcarrier; Wherein, K is the integer greater than 1;

Concrete, calculate the land mobile distance between two histograms, comprising:

Two histograms to be compared are regarded as two stack features;

With the position as feature, the position in interval, with the weight of the counting in the respective bins as correspondence;

According to position and the weight of described feature, calculate the land mobile distance between two histograms.

Concrete, two groups of sizes are respectively the feature of m and n

With

U wherein _iAnd v _jRepresented respectively i in every stack features and the position of j element, and p _iAnd q _jRepresented respectively its corresponding weight, then the EMD distance definition of this two stack features is as follows:

$\mathrm{EMD}(P,Q)=\underset{F=\left\{f_{\mathrm{ij}}\right\}}{\min }\frac{{\mathrm{\Σ}}_{i,j}{f}_{\mathrm{ij}}{d}_{\mathrm{ij}}}{{\mathrm{\Σ}}_{i,j}{f}_{\mathrm{ij}}}$

And satisfy:

$\underset{j}{\mathrm{\Σ}}{f}_{\mathrm{ij}}\≤p_i,\underset{i}{\mathrm{\Σ}}{f}_{\mathrm{ij}}\≤q_j,\underset{i,j}{\mathrm{\Σ}}{f}_{\mathrm{ij}}\≤\min \{\underset{i}{\mathrm{\Σ}}{p}_i,\underset{j}{\mathrm{\Σ}}{q}_j\},f_{\mathrm{ij}}\≥0$

Histogram can be regarded one group of special feature as, therefore calculate between two histograms EMD apart from the time, with the position as feature, the position in interval, the counting in the respective bins can be calculated EMD distance between two histograms according to above-mentioned formula as the weight of correspondence.

The EMD distance of calculating separately CFR amplitude histogram on each subcarrier is the similarity for each subcarrier feature in the large scale time range on the counting statistics meaning, and the frequency-domain structure that keeps CFR on the small scale category, thereby both eliminated to a certain extent the impact of random perturbation, obtained again higher space region calibration.

Step 1022: with all K cumulative the summations as the similarity between two location fingerprint of land mobile distance.

Embodiments of the invention at first calculate the EMD distance of the CFR amplitude histogram between the corresponding subcarrier, then with all K cumulative the summations as the similarity between two location fingerprint of EMD distance.

Because, (the OFDM of orthogonal frequency division multiplexi, Orthogonal Frequency Division Multiplexing) the sub-carrier frequencies interval has surpassed typical indoor coherence bandwidth, thereby its decay is separate, and human body corresponds to variation in the whole frequency range to the impact of each bar time domain propagation path, so that the impact that each subcarrier is subject to shared weight when calculating the general impacts that signal is subject to is identical.Therefore, the directly summation of EMD distance that each subcarrier is corresponding is as the similarity between two location fingerprint.

Step 103: the situation of judging user present position in the area to be monitored according to described similarity;

Step 103 specifically comprises:

Position corresponding with the highest location fingerprint of location fingerprint similarity to be measured in the decision data storehouse is the current position of user;

Or the location fingerprint similarity when not having the user in location fingerprint to be measured and the location fingerprint database is when the highest, and judging in the current area to be monitored does not have the user.

In order to improve the accuracy of judgement, the location fingerprint of demarcating in advance in CFR location fingerprint and the database in a series of sliding windows can be mated, when most of CFR location fingerprint in these sliding windows all to database in location fingerprint when the user is arranged when more similar, judge current these a series of sliding windows corresponding in the middle of constantly have the user to enter the area to be monitored.Because the method for location fingerprint identification has been demarcated the CFR feature of all directions in the area to be monitored in advance, and no matter which kind of relative bearing user and receiver are in, the feature of its CFR feature when not having the user compared, location fingerprint when having the user to be in this orientation in the database more all, therefore, the method of location fingerprint identification has been utilized the CFR feature on all directions, as long as gathered the CFR feature on all directions of demarcating in advance in the database, avoid the oriented detection range that causes owing to the transmitter-receiver link structure on just can be largely.

This method that the present embodiment provides can detect not only whether the user is arranged in the area to be monitored, also can judge the relative direction of user and receiver, has improved discrimination and robustness, has realized that well the user of omnidirectional detects.

Embodiment 2

Fig. 2 is the indoor wireless omnidirectional passive user's detection method flow chart based on threshold test that the embodiment of the invention provides.

Embodiments of the invention 2 provide a kind of indoor wireless omnidirectional based on threshold test passive user's detection method.As shown in Figure 2, the basic step of the method comprises:

Step 201: from the indoor wireless local area network physical layer information, extract location fingerprint to be measured (LF);

When carrying out this step, only need to extract the location fingerprint that does not have the user to be in the monitored space.Like this, when in judging the area to be monitored, whether the user being arranged, only need the location fingerprint contrast of CFR location fingerprint to be measured when not having the user got final product, because near the existence of human body impact to received signal is often much larger than the impact to received signal of distant place environment.

Step 202: the similarity of the location fingerprint when calculating described location fingerprint to be measured and no user.

When carrying out this step, for detection no user is arranged, the similarity threshold γ of location fingerprint in the time of at first will setting a location fingerprint to be measured and no user:

$\mathrm{\γ}=(1+\mathrm{\δ})\·\underset{k\∈K}{\max }\left\{d(s_k,s_{\mathrm{out}})\right\}$

Wherein δ is a predefined constant, s _kThe CFR location fingerprint that records when not having the user in the area to be monitored, s _OutCFR location fingerprint when expression is selected as the current user of not having of expression.

The meaning representation of following formula, when in the area to be monitored, not having the user, receiver records one group of K CFR location fingerprint, calculate the EMD distance between this K location fingerprint, wherein can represent the feature of this K location fingerprint apart from a CFR location fingerprint of sum minimum with all the other location fingerprint, therefore can be with the location fingerprint standard of this CFR location fingerprint when not having the user in the area to be monitored.Maximum deviation the EMD distance between the CFR feature of other K-1 CFR location fingerprint and this standard multiply by 1+ δ, obtains the threshold gamma of a CFR location fingerprint, this CFR location fingerprint as judging the standard that has no user to enter in the area to be monitored.Wherein constant δ can obtain by a small amount of training according to different environmental conditions.

Step 203: judge in the area to be monitored that according to similarity no user is arranged;

When carrying out this step, for detection no user is arranged, only need to be the threshold of setting in CFR location fingerprint to be measured and the step 102, the similarity of the location fingerprint when location fingerprint to be measured and described no user is during greater than the threshold value of setting, and judging in the current area to be monitored does not have the user.The similarity of the location fingerprint when location fingerprint to be measured and described no user is during less than the threshold value set, and judging in the current area to be monitored has the user.The part identical with embodiment 1 do not done and given unnecessary details among the above embodiment 2.

This detection method based on threshold value that the present embodiment provides only needs training in advance seldom normally to upgrade, this threshold value renewal process can be easily in the situation that the area to be monitored should be not have the user to carry out, such as the threshold value renewal process of above-mentioned passive user's monitoring equipment of museum interior administration, can in museum's Time Out section, carry out.

Embodiment 3

Fig. 3 is indoor wireless omnidirectional passive user's detection system structural representation that the embodiment of the invention 3 provides.As shown in Figure 3, wherein comprise transmitter 301 and receiver 303 among the figure, also have user 302.

The system that embodiments of the invention 3 provide a kind of indoor wireless passive user of omnidirectional to detect, this system comprises:

Transmitter 301 and receiver 303, transmitter and 301 receivers 303 are by the mutual communication of WLAN (wireless local area network); What the present embodiment adopted is the WLAN (wireless local area network) of disposing in the indoor environment, can adopt 802.11n, 802.11a/g etc. to adopt the protocol of wireless local area network of OFDM technology.

Transmitter 301 is used for wireless signal emission; The transmitter 301 that the present embodiment preferably adopts is the indoor wireless local network connecting point of having disposed (Access Point, AP).

Receiver 303 is used for the wireless signal of receiver/transmitter 301 emissions, extracts location fingerprint to be measured from this signal; Calculate the similarity of location fingerprint in location fingerprint to be measured and the location fingerprint database; Judge no user 302 to be arranged and with the situation of present position, 302 family in the area to be monitored according to similarity.

The receiver 303 that the present embodiment preferably adopts is for having installed the commercial notebook computer of Intel 5300 wireless network cards.Receiver 301 extracts channel condition information (Channel State Information, CSI) from the packet that transmitter 301 sends.Each CSI has represented real part and the imaginary part of an OFDM subchannel.Utilize the Intel5300 wireless network card to read 30 CSI information on the subcarrier, and be converted into 30 CFR components.The CFR information of receiver in 303 each record a period of times, and the histogram of statistics CFR amplitude is as the CFR location fingerprint.

The passive user's detection system of the indoor wireless omnidirectional that the present embodiment provides and embodiment of the method belong to same design, and its specific implementation process sees embodiment of the method for details and repeats no more here.

This system that the present embodiment provides has improved discrimination and robustness, has realized that well the user of omnidirectional detects.

The all or part of step that one of ordinary skill in the art will appreciate that realization above-described embodiment can be finished by hardware, also can come the relevant hardware of instruction to finish by program, described program can be stored in a kind of computer-readable recording medium, the above-mentioned storage medium of mentioning can be read-only memory, disk or CD etc.

It below only is the explanation of doing for the preferred embodiments of the present invention and know-why thereof; and be not the restriction that technology contents of the present invention is carried out; anyly be familiar with those skilled in the art in technical scope disclosed in this invention; the variation of easily being expected or replacement all should be encompassed in protection scope of the present invention.

Claims (10)

1. the passive user's detection method of indoor wireless omnidirectional is characterized in that, described method comprises:

From the indoor wireless local area network physical layer information, extract location fingerprint to be measured (LF);

Calculate described location fingerprint to be measured and the similarity of measuring in advance good location fingerprint;

Judge the situation that in the area to be monitored no user is arranged or further judge the user present position according to described similarity.

2. method according to claim 1 is characterized in that, describedly extracts location fingerprint to be measured from the indoor wireless local area network physical layer information, comprising:

Will be owing to the distance of user distance receiver be different with the orientation, and the variation in the radio signal propagation path that causes, convert the statistic histogram of channel frequency response (CFR) to, utilize described statistic histogram as described location fingerprint.

3. method according to claim 2 is characterized in that, with the amplitude histogram of the channel frequency response on a plurality of subcarriers as the location fingerprint of extracting from the indoor wireless local area network physical layer.

4. method according to claim 3 is characterized in that, each histogram component obtains by the channel frequency response amplitude of calculating a predefined time window.

5. method according to claim 1 is characterized in that, described location fingerprint when measuring in advance good location fingerprint and comprising the location fingerprint database set up in advance or no user.

6. method according to claim 5 is characterized in that, the described location fingerprint database of setting up in advance is:

The user is not when having the user in receiver has different distance and bearing angles and area to be monitored, and described receiver detects the feature of channel frequency response, the feature of described channel frequency response as location fingerprint, the database of foundation.

7. method according to claim 1 is characterized in that, described calculating location fingerprint to be measured and the similarity of measuring in advance good location fingerprint comprise:

The channel frequency response amplitude histogram vector of comparing for two calculates the land mobile distance of the channel frequency response amplitude histogram between described vectorial the corresponding K subcarrier;

With all K cumulative the summations as the similarity between two location fingerprint of land mobile distance;

Wherein, K is the integer greater than 1.

8. method according to claim 7 is characterized in that, the land mobile distance between two histograms of described calculating comprises:

According to two histogrammic positions to be compared and weight, calculate the land mobile distance between two histograms.

9. method according to claim 1 is characterized in that, judges according to described similarity to comprise the situation that in the area to be monitored no user is arranged or further judge the user present position:

The similarity of the location fingerprint when location fingerprint to be measured and described no user is during greater than the threshold value set, and judging in the current area to be monitored does not have the user;

The similarity of the location fingerprint when location fingerprint to be measured and described no user is during less than the threshold value set, and judging in the current area to be monitored has the user;

Perhaps:

Judge in the described database that the position corresponding with the highest location fingerprint of location fingerprint similarity to be measured is the current position of user;

Or the location fingerprint similarity when not having the user in location fingerprint to be measured and the described location fingerprint database is when the highest, and judging in the current area to be monitored does not have the user.

10. the passive user's detection system of indoor wireless omnidirectional is characterized in that, described system comprises:

Transmitter and receiver, described transmitter and described receiver are by the mutual communication of WLAN (wireless local area network);

Described transmitter is used for wireless signal emission;

Described receiver is used for receiving the wireless signal of described transmitter emission, extracts location fingerprint to be measured from described signal; Calculate described location fingerprint to be measured and the similarity of measuring in advance good location fingerprint; Judge the situation that in the area to be monitored no user is arranged or further judge the user present position according to described similarity.

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