CN103220780A - Indoor positioning method, device and system - Google Patents

Abstract

The invention discloses an indoor positioning method, an indoor positioning device and an indoor positioning system, wherein an AP (Access Point) is selected and is applied to positioning a mobile terminal, so that positioning precision can be improved. The method comprises the steps of selecting one or more of target APs from at least three APs according to signal quality of the AP when the mobile terminal can receive signals of the at least three APs simultaneously; and positioning the mobile terminal according to a signal of each target AP and signal information of each target AP in a prestored fingerprint database. The device comprises a selecting unit used for selecting the one or more of target APs from the at least three APs according to the signal quality of the AP when the mobile terminal receives signals of the at least three APs simultaneously; and a positioning unit used for positioning the mobile terminal according to the signal of each target AP and the signal information of each target AP in the prestored fingerprint database. According to the indoor positioning method, the indoor positioning device and the indoor positioning system, the main aim of the embodiment is indoor positioning, and positioning precision can be improved.

Description

Indoor orientation method, Apparatus and system

Technical field

The present invention relates to field of locating technology, particularly a kind of indoor orientation method, Apparatus and system.

Background technology

The location technology of fingerprint matching is a kind of technology that realizes indoor positioning.The location technology of fingerprint matching can be divided into two stages, i.e. off-line phase (Offline stage) and online stage (Online stage).After off-line phase was meant and chooses fingerprint point (fingerprint point also can be called fingerprint collecting point or reference point), each fingerprint point was gathered AP(access point around it, and English full name is Access Point) signal, the signal of these AP stored sets up fingerprint base.After the online stage is meant and sets up fingerprint base, the signal of AP around portable terminal receives, signal and the signal in the database that portable terminal is received carry out matching operation, the position at the portable terminal place that finally draws.

In the practice, online stage portable terminal may receive the signal vector of a plurality of AP simultaneously, but the signal vector of some AP is little to coupling calculating effect, chooses such signal vector and carries out matching operation, influences positioning accuracy.

Summary of the invention

The embodiment of the invention provides a kind of indoor orientation method, Apparatus and system, uses the AP that chooses portable terminal is positioned, thereby can improve positioning accuracy.

The embodiment of the invention adopts following technical scheme:

First aspect provides a kind of indoor orientation method, comprising:

When portable terminal received the signal of at least three AP simultaneously, according to signal quality select target AP from described at least three AP of access point AP, described target AP was one or more; Signal message according to target AP described in the signal of described target AP and the fingerprint base that prestores positions described portable terminal.

Alternatively, described signal quality select target AP from described at least three AP according to AP comprises:

According to the signal strength signal intensity of each AP among described at least three AP, from described three AP, select at least one AP at least, as described target AP; Perhaps, per at least three AP among described at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of geometric dilution of precision GDOP minimum, as described target AP; Perhaps, according to the signal strength signal intensity of each AP among described at least three AP, from described three AP, select at least three AP at least, per at least three AP among selected at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as described target AP.

Alternatively, according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among described at least three AP, wherein, P _iBe the signal strength signal intensity that described portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for described portable terminal position _i, y _i, z _i) distance,

X _σAverage be 0.

Alternatively, according to the AP in every group of AP combination to the distance vector of described portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

Alternatively, described according to each AP in every group of AP combination to the distance vector of described portable terminal, with the direction cosines amount of reference frame reference axis, determine that the GDOP of every group of AP combination comprises:

Determine in every group of AP combination each AP to the distance vector of described portable terminal, with the direction cosines amount of reference frame reference axis; With at least three direction cosines amounts determining, set up every group of corresponding observing matrix of AP combination, according to every group of corresponding observing matrix of AP combination, determine the GDOP of every group of AP combination.

Second aspect provides a kind of indoor positioning device, comprising:

Selected cell is used at least when portable terminal receives the signal of three AP simultaneously, and according to signal quality select target AP from described at least three AP of access point AP, described target AP is one or more; Positioning unit is used for the signal message according to target AP described in the signal of described target AP and the fingerprint base that prestores, and described portable terminal is positioned.

Alternatively, described selected cell comprises following arbitrary subelement:

First subelement is used for the signal strength signal intensity (as RSSI) according to described at least three each AP of AP, selects at least one AP at least from described three AP, as described target AP; Second subelement is used for per at least three AP of described at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as described target AP; The 3rd subelement, be used for signal strength signal intensity, from described three AP, select at least three AP at least, per at least three AP among selected at least three AP are formed one group of AP combination according to described at least three each AP of AP, with one group of AP that the AP combination comprises of GDOP minimum, as described target AP.

Alternatively, described first subelement specifically is used for according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among described at least three AP; Described the 3rd subelement specifically is used for according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among described at least three AP; Wherein, P _iBe the signal strength signal intensity that described portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for described portable terminal position _i, y _i, z _i) distance, $d_i=\sqrt{{(x-x_i)}^2+{(y-y_i)}^2+{(z-z_i)}^2},$ X _σAverage be 0.

Alternatively, described second subelement, specifically be used for according to the AP of every group of AP combination to the distance vector of described portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination; Described the 3rd subelement, specifically be used for according to the AP of every group of AP combination to the distance vector of described portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

The third aspect provides a kind of indoor locating system, comprises indoor positioning device and portable terminal, wherein:

Described indoor positioning device comprises the indoor positioning device that second aspect provides;

Described portable terminal when being used to receive the signal of at least three AP, is notified described indoor positioning device, makes described indoor positioning device select target AP from described at least three AP position described portable terminal.

Based on technique scheme, the indoor orientation method that the embodiment of the invention provides, Apparatus and system, when portable terminal receives the signal of at least three AP simultaneously, signal quality select target AP from least three AP according to AP, signal message according to target AP in the signal of target AP and the fingerprint base that prestores positions portable terminal.Like this, determine to be more suitable for the AP that is used to locate by choosing, thereby can improve positioning accuracy.

Description of drawings

In order to be illustrated more clearly in the technical scheme in the embodiment of the invention, the accompanying drawing of required use is done to introduce simply in will describing embodiment below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

The flow chart of the indoor orientation method that Fig. 1 provides for one embodiment of the invention;

A kind of signal intensity profile schematic diagram that Fig. 2 provides for the embodiment of the invention;

The flow chart of the indoor positioning sending method that Fig. 3 provides for another embodiment of the present invention;

The structural representation of the indoor positioning device that Fig. 4 provides for one embodiment of the invention;

The structural representation of the indoor positioning device that Fig. 5 provides for another embodiment of the present invention;

The structural representation of a kind of indoor locating system that Fig. 6 provides for the embodiment of the invention.

Embodiment

For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer, below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly described, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.

The embodiment of the invention can be applied to various communication systems, WCDMA(Wideband Code Division Multiple Access for example, Wideband Code Division Multiple Access (WCDMA)) system, LTE(Long Term Evolution, Long Term Evolution) system etc.Signal strength signal intensity in the embodiment of the invention can be indicated for the signal strength signal intensity that RSSI(receives, and English full name is Received Signal Strength Indication).

The present invention is in the example, portable terminal be have communication function by, include but not limited to mobile phone, panel computer etc.

See also Fig. 1, the embodiment of the invention provides a kind of indoor orientation method, and this sending method can comprise:

101, when portable terminal receives the signal of at least three AP simultaneously, according to signal quality select target AP from these at least three AP of AP, this target AP is one or more.

Wherein, this signal quality can be signal strength signal intensity, and/or the GDOP(geometric dilution of precision, and English full name is Geometric Dilution of Precision) (location overall error).

102, according to the signal message of this target AP in the signal of this target AP and the fingerprint base that prestores, this portable terminal is positioned.

The embodiment of the invention can realize by the indoor positioning device, and this indoor positioning device can be for computer system etc., and the embodiment of the invention is not done qualification.

The indoor orientation method of the embodiment of the invention, when portable terminal receives the signal of at least three AP simultaneously, according to signal quality select target AP from least three AP of AP, the signal message according to target AP in the signal of target AP and the fingerprint base that prestores positions portable terminal.Like this, determine to be more suitable for the AP that is used to locate by choosing, thereby can improve positioning accuracy.

In the embodiment of the invention, alternatively, from these at least three AP, during select target AP, can use following any one method according to the signal quality of AP in above-mentioned 101:

Method one

According to the signal strength signal intensity (as RSSI) of each AP among these at least three AP, from these three AP, select at least one AP at least, as this target AP.

For example, can be according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among these at least three AP, wherein, P _iBe the signal strength signal intensity that this portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for this portable terminal position _i, y _i, z _i) distance,

X _σAverage be 0, variance is σ ²Gaussian noise.The value difference of n in different channel circumstances, common span is 2-6.

Fig. 2 is the schematic diagram that concerns of signal strength signal intensity (RSSI) with the distance of AP.Along with the increase of distance, the more and more littler RSSI of slope absolute value changes, and change sensitivity more and more slower, that RSSI adjusts the distance reduces as shown in Figure 2.

In the embodiment of the invention, can from these three AP, select at least one AP at least according to the signal strength signal intensity (RSSI) of AP.For example, select signal strength signal intensity greater than the AP of pre-set threshold value as this target AP.This pre-set threshold value can be provided with change according to different application scenarioss.

Like this, based on this target AP that signal strength signal intensity (RSSI) is selected, the discrimination between the selected target collection point is higher, can improve positioning accuracy.

Method two

At least per three AP among these at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as this target AP.

For example, can according to the AP in every group of AP combination to the distance vector of this portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

Further, according to each AP in every group of AP combination to the distance vector of this portable terminal, with the direction cosines amount of reference frame reference axis, when determining the GDOP of every group of AP combination, can determine every group of each AP in the AP combination to the distance vector of this portable terminal, with the direction cosines amount of reference frame reference axis; With at least three direction cosines amounts determining, set up every group of corresponding observing matrix of AP combination, according to every group of corresponding observing matrix of AP combination, determine the GDOP of every group of AP combination.

Wherein, overall error when GDOP represents to locate, GDOP comprises position (PDOP), level (HDOP), vertical (VDOP) and four parameters of TDOP-Time Dilution of Precision (TDOP), and PDOP, HDOP, VDOP, TDOP represent site error, horizontal position error, the upright position sum of errors clocking error multiplication factor to range error respectively.Relative position during the location between the AP, the difference of relative position causes the Different Effects positioning accuracy of GDOP between portable terminal and the AP.When other condition was identical, the GDOP value was more little, and positioning accuracy is high more ^{A mistake! Do not find Reference source.}。

In the embodiment of the invention, can determine GDOP, PDOP, HDOP, VDOP, TDOP according to observing matrix H, for example, observing matrix H, G=(H ^TH) ^-1, diagonal entry is g _Ii(i=1 ..., 4), then

GDOP=(g ₁₁+g ₂₂+g ₃₃+g ₄₄) ^1/2

PDOP=(g ₁₁+g ₂₂+g ₃₃) ^1/2

HDOP=(g ₁₁+g22) ^1/2

VDOP=(g ₃₃) ^1/2

TDOP=(g ₄₄) ^1/2

This observing matrix H can for

$\left[\begin{array}{cccc}{a}_{x1}& a_{y1}& a_{z1}& 1\\ a_{x2}& a_{y2}& a_{z2}& 1\\ a_{x3}& a_{y3}& a_{z3}& 1\\ \·\·\·& \·\·\·& \·\·\·& \·\·\·\\ a_{\mathrm{xn}}& a_{\mathrm{yn}}& a_{\mathrm{zn}}& 1\end{array}\right]$

Interim, a _Xi, a _Yi, a _Zi(i=1 ..., n) AP in every group of AP of expression combination is to the distance vector of this portable terminal and X, the Y of reference frame, the direction cosines of Z axle.N is for participating in the AP number of location, and n is the integer more than or equal to 3.

Method three

According to the signal strength signal intensity of each AP among these at least three AP, from these three AP, select at least three AP at least, per at least three AP among selected at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as this target AP.

Can be according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among these at least three AP, wherein, P _iBe the signal strength signal intensity that this portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for this portable terminal position _i, y _i, z _i) distance, $d_i=\sqrt{{(x-x_i)}^2+{(y-y_i)}^2+{(z-z_i)}^2},$ X _σAverage be 0.

Determine the AP signal strong the specific implementation method see also said method one.

Can according to the AP in every group of AP combination to the distance vector of this portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

For example, can determine in every group of AP combination each AP to the distance vector of this portable terminal, with the direction cosines amount of reference frame reference axis; With at least three direction cosines amounts determining, set up every group of corresponding observing matrix of AP combination, according to every group of corresponding observing matrix of AP combination, determine the GDOP of every group of AP combination.

The specific implementation method of determining every group of AP combination GDOP sees also said method two.

The indoor orientation method of the embodiment of the invention, when portable terminal receives the signal of at least three AP simultaneously, according to signal quality select target AP from least three AP of AP, the signal message according to target AP in the signal of target AP and the fingerprint base that prestores positions portable terminal.Like this, determine to be more suitable for the AP that is used to locate by choosing, thereby can improve positioning accuracy.

Describe the specific implementation process of the indoor orientation method of the embodiment of the invention below in detail.

See also Fig. 3, the another kind of indoor orientation method that the embodiment of the invention provides, the indoor orientation method of the corresponding embodiment of Fig. 3, based at least 3 AP of location need of WLAN location fingerprint, positioning stage, portable terminal is received n ₁The signal of individual AP.

As shown in Figure 3, this indoor orientation method can comprise:

301, as portable terminal reception n ₁During the signal of individual AP, judge whether n ₁〉=3.

Work as n ₁, carry out 302 at 〉=3 o'clock; Work as n ₁, use the AP signal execution 305 that portable terminal receives at＜3 o'clock.

302, select AP based on RSSI, obtain n ₁RSSI is greater than predetermined threshold value RSSI among the individual AP _ThN ₂Individual AP.

303, judge whether n ₂〉=3.

Work as n ₂, carry out 304 at 〉=3 o'clock; Work as n ₂＜3 o'clock, according to n ₂The signal of individual AP carries out 305.

304, according to AP signal cover and positioning accuracy, the AP number n that is identified for locating ₃(n ₃For more than or equal to 3 integer), right Every group of AP combination calculate corresponding GDOP value respectively, select the AP of the PDOP value minimum AP in making up.

305, the signal according to selected AP carries out matching operation, determines the position of portable terminal.

The indoor orientation method of the embodiment of the invention of Fig. 3 correspondence is only done concise and to the point description, and implementation procedure sees also the indoor orientation method of other embodiment of the invention in detail.

The indoor orientation method of the embodiment of the invention, when portable terminal receives the signal of at least three AP simultaneously, according to signal quality select target AP from least three AP of AP, the signal message according to target AP in the signal of target AP and the fingerprint base that prestores positions portable terminal.Like this, determine to be more suitable for the AP that is used to locate by choosing, thereby can improve positioning accuracy.

See also Fig. 4, a kind of indoor positioning device that the embodiment of the invention provides, this device comprises: selected cell 41 and positioning unit 42, wherein:

Selected cell 41 is used at least when portable terminal receives the signal of three AP simultaneously, and according to signal quality select target AP from these at least three AP of access point AP, this target AP is one or more;

Positioning unit 42 is used for the signal message according to the signal of this target AP and this target AP of fingerprint base of prestoring, and this portable terminal is positioned.

As shown in Figure 5, alternatively, selected cell 41 comprises following arbitrary subelement:

First subelement 411 is used for the signal strength signal intensity according to these at least three each AP of AP, selects at least one AP at least from these three AP, as this target AP;

Second subelement 412 is used for per at least three AP of these at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as this target AP;

The 3rd subelement 413, be used for signal strength signal intensity, from these three AP, select at least three AP at least, per at least three AP among selected at least three AP are formed one group of AP combination according to these at least three each AP of AP, with one group of AP that the AP combination comprises of GDOP minimum, as this target AP.

In the embodiment of the invention, alternatively, first subelement 411 specifically is used for according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among these at least three AP;

In the embodiment of the invention, alternatively, the 3rd subelement 413 specifically is used for according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among these at least three AP;

Wherein, P _iBe the signal strength signal intensity that this portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for this portable terminal position _i, y _i, z _i) distance,

X _σAverage be 0.

In the embodiment of the invention, alternatively, this second subelement 412, specifically be used for according to the AP of every group of AP combination to the distance vector of this portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination;

In the embodiment of the invention, alternatively, the 3rd subelement 413, specifically be used for according to the AP of every group of AP combination to the distance vector of this portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

The function of each unit only is concise and to the point the description in the indoor positioning device of the embodiment of the invention, and implementation procedure sees also the embodiment of above-mentioned indoor orientation method in detail.The indoor positioning device of the embodiment of the invention can be realized above-mentioned indoor orientation method.

The indoor positioning device of the embodiment of the invention, when portable terminal receives the signal of at least three AP simultaneously, according to signal quality select target AP from least three AP of AP, the signal message according to target AP in the signal of target AP and the fingerprint base that prestores positions portable terminal.Like this, determine to be more suitable for the AP that is used to locate by choosing, thereby can improve positioning accuracy.

As shown in Figure 6, the embodiment of the invention provides a kind of indoor locating system, comprises indoor positioning device 61 and portable terminal 62, wherein:

The indoor positioning device that indoor positioning device 61 provides for the invention described above embodiment;

Portable terminal 62 when being used to receive the signal of at least three AP, is notified this indoor positioning device, makes this indoor positioning device select target AP from these at least three AP position this portable terminal.

The indoor locating system of the embodiment of the invention, when portable terminal receives the signal of at least three AP simultaneously, according to signal quality select target AP from least three AP of AP, the signal message according to target AP in the signal of target AP and the fingerprint base that prestores positions portable terminal.Like this, determine to be more suitable for the AP that is used to locate by choosing, thereby can improve positioning accuracy.

Embodiment of the invention main cause indoor positioning can improve positioning accuracy.

Need to prove: the indoor positioning device that the foregoing description provides, only the division with above-mentioned each functional unit is illustrated, in the practical application, can as required the above-mentioned functions distribution be finished by different functional units or module, the internal structure that is about to the indoor positioning device is divided into different functional units or module, to finish all or part of function described above.In addition, indoor positioning device and indoor orientation method embodiment that the foregoing description provides belong to same design, and its specific implementation process sees method embodiment for details, repeats no more here.

The invention described above embodiment sequence number is not represented the quality of embodiment just to description.

The all or part of step that one of ordinary skill in the art will appreciate that realization the foregoing description can be finished by hardware, also can instruct relevant hardware 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 a read-only memory, disk or CD etc.

The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. an indoor orientation method is characterized in that, comprising:

When portable terminal received the signal of at least three AP simultaneously, according to signal quality select target AP from described at least three AP of access point AP, described target AP was one or more;

Signal message according to target AP described in the signal of described target AP and the fingerprint base that prestores positions described portable terminal.

2. method according to claim 1 is characterized in that, described signal quality select target AP from described at least three AP according to AP comprises:

According to the signal strength signal intensity of each AP among described at least three AP, from described three AP, select at least one AP at least, as described target AP;

Perhaps, per at least three AP among described at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of geometric dilution of precision GDOP minimum, as described target AP;

Perhaps, according to the signal strength signal intensity of each AP among described at least three AP, from described three AP, select at least three AP at least, per at least three AP among selected at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as described target AP.

3. according to the described method of claim 2, it is characterized in that, according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among described at least three AP, wherein, P _iBe the signal strength signal intensity that described portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for described portable terminal position _i, y _i, z _i) distance, $d_i=\sqrt{{(x-x_i)}^2+{(y-y_i)}^2+{(z-z_i)}^2},$ X _σAverage be 0.

4. according to the described method of claim 2, it is characterized in that, according to the AP in every group of AP combination to the distance vector of described portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

5. according to the described method of claim 4, it is characterized in that, described according to each AP in every group of AP combination to the distance vector of described portable terminal, with the direction cosines amount of reference frame reference axis, determine that the GDOP of every group of AP combination comprises:

Determine in every group of AP combination each AP to the distance vector of described portable terminal, with the direction cosines amount of reference frame reference axis;

With at least three direction cosines amounts determining, set up every group of corresponding observing matrix of AP combination, according to every group of corresponding observing matrix of AP combination, determine the GDOP of every group of AP combination.

6. an indoor positioning device is characterized in that, comprising:

Selected cell is used at least when portable terminal receives the signal of three AP simultaneously, and according to signal quality select target AP from described at least three AP of access point AP, described target AP is one or more;

Positioning unit is used for the signal message according to target AP described in the signal of described target AP and the fingerprint base that prestores, and described portable terminal is positioned.

7. device according to claim 6 is characterized in that, described selected cell comprises following arbitrary subelement:

First subelement is used for the signal strength signal intensity according to described at least three each AP of AP, selects at least one AP at least from described three AP, as described target AP;

Second subelement is used for per at least three AP of described at least three AP are formed one group of AP combination, with one group of AP that the AP combination comprises of GDOP minimum, as described target AP;

The 3rd subelement, be used for signal strength signal intensity, from described three AP, select at least three AP at least, per at least three AP among selected at least three AP are formed one group of AP combination according to described at least three each AP of AP, with one group of AP that the AP combination comprises of GDOP minimum, as described target AP.

8. according to the described device of claim 7, it is characterized in that described first subelement specifically is used for according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among described at least three AP;

Described the 3rd subelement specifically is used for according to P _i=P ₀-10nlgd _i+ X _σDetermine the signal strength signal intensity of each AP among described at least three AP;

Wherein, P _iBe the signal strength signal intensity that described portable terminal receives, P ₀Be the signal strength signal intensity that range transmission node 1m place receives, n is the fading factor of channel, d _i(x, y is z) at least three beaconing nodes (x for described portable terminal position _i, y _i, z _i) distance,

X _σAverage be 0.

9. according to the described device of claim 7, it is characterized in that, described second subelement, specifically be used for according to the AP of every group of AP combination to the distance vector of described portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination;

Described the 3rd subelement, specifically be used for according to the AP of every group of AP combination to the distance vector of described portable terminal, with the direction cosines of reference frame reference axis, determine the GDOP of every group of AP combination.

10. an indoor locating system is characterized in that, comprises indoor positioning device and portable terminal, wherein:

Described indoor positioning device comprises each described indoor positioning device in the claim 6 to 8;

Described portable terminal when being used to receive the signal of at least three AP, is notified described indoor positioning device, makes described indoor positioning device select target AP from described at least three AP position described portable terminal.

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