JP7229714B2 - Position estimation device, wireless device, position estimation system, and position estimation method - Google Patents

Description

The present disclosure relates to position estimation devices, wireless devices, position estimation systems, and position estimation methods.

2. Description of the Related Art In recent years, with the development of wireless communication technology and the spread of wireless terminals, the demand for location estimation of wireless terminals using wireless communication technology is increasing. For example, a method has been proposed for estimating the position of an indoor wireless terminal by collecting fingerprints of wireless LANs and constructing a radio map (see Patent Document 1).

JP 2016-99349 A

One aspect of the present disclosure provides improved location estimation devices, wireless devices, location estimation systems, and location estimation methods for determining placement of a second wireless device that provides a good location estimate for a third wireless device. contribute to

A position estimation device according to an aspect of the present disclosure, based on a first reception strength of a first radio signal transmitted by a plurality of first radio devices at a plurality of second radio devices, the plurality of a decision circuit for selecting at least two of the second radio devices; and a second reception strength of a second radio signal transmitted by a third radio device at said at least two selected second radio devices. and an estimating circuit for estimating the position of the third radio apparatus based on the above.

A wireless device according to an aspect of the present disclosure includes a wireless communication device that intercepts a first wireless signal destined for another wireless device, and a measurement circuit that measures the reception strength of the first wireless signal. , the wireless communication device transmits a wireless signal including information indicating the reception strength of the first wireless signal, the wireless communication device intercepts a second wireless signal addressed to another wireless device; The measuring circuit measures the reception strength of the second radio signal, and the radio communication device transmits a radio signal including information indicating the reception strength of the second radio signal.

A position estimation system according to one aspect of the present disclosure includes a position estimation device according to one aspect of the present disclosure, a wireless device according to one aspect of the present disclosure, connected to the position estimation device, and wirelessly communicating with the wireless device. and an access point.

A position estimation method according to an aspect of the present disclosure is based on a first received strength of a first radio signal transmitted by a plurality of first radio devices at a plurality of second radio devices, selecting at least two of the second radio devices, based on a second received strength of a second radio signal transmitted by a third radio device at said at least two selected second radio devices , estimating the position of the third radio apparatus.

These generic or specific aspects may be realized by systems, methods, integrated circuits, computer programs, or recording media, and any of the systems, devices, methods, integrated circuits, computer programs and recording media may be implemented in any combination.

According to one aspect of the present disclosure, it is possible to determine the placement of the second wireless device that performs a good position estimation of the third wireless device.

Further advantages and advantages of one aspect of the present disclosure are apparent from the specification and drawings. Such advantages and/or advantages are provided by the several embodiments and features described in the specification and drawings, respectively, not necessarily all provided to obtain one or more of the same features. no.

A diagram showing an example of the configuration of a wireless communication system according to the present disclosure A diagram showing an example of a configuration of a position estimation device according to the present disclosure A diagram showing an example of the configuration of an access point according to the present disclosure A diagram showing an example of a configuration of a wireless node according to the present disclosure A diagram showing an example of arrangement of candidate positions and reference positions when determining an anchor node according to the present disclosure Flowchart showing an example of operation when determining an anchor node according to the present disclosure A diagram showing an example of a radio signal sequence in steps S603 and S604 when determining an anchor node A diagram showing an example of an RSSI (Receive Signal Strength Indicator, received signal strength) matrix A diagram showing an example of a fingerprint matrix A diagram showing a specific example of RSSI values of radio signals transmitted by a location node and intercepted by a candidate node. A diagram showing a specific example of RSSI values of radio signals transmitted by a location node and intercepted by a candidate node. A diagram showing a specific example of RSSI values of radio signals transmitted by a location node and intercepted by a candidate node. A diagram showing a specific example of data representing an RSSI matrix in a table format A diagram showing a specific example of data representing a fingerprint matrix in table format A diagram showing an example in which four anchor nodes are selected in step S606 when determining anchor nodes. Flowchart showing an example of operation during position estimation by the position estimation device according to the present disclosure A diagram showing an example of a radio signal sequence in steps S1103 and S1104 during position estimation

In Patent Document 1, movement of a mobile device in a divided area of an indoor map is machine-learned as a position state transition model, and wireless LAN fingerprints collected by the movement of the mobile device are labeled with location information. to automatically build a radio map. However, it is assumed that the access points that form the basis of the wireless LAN fingerprint have already been installed, and no consideration is given to changing the location or number of access points.

As a result, depending on the range in which the mobile device may be present, there is no guarantee that a fingerprint for easy identification of the location of the mobile device will be obtained. Also, when determining the number and locations of new access points to be installed so as to obtain a fingerprint that facilitates identification of the locations of mobile devices, the number of combinations of mobile device locations and access point installation locations is As the number increases, the time and cost required for the measurements involved in the decision increase, and the decision becomes difficult.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, the embodiment described below is an example, and the present disclosure is not limited to the following embodiment.

(Embodiment)
FIG. 1 shows an example configuration of a position estimation system 1000 according to the present disclosure.

A position estimation system 1000 includes a position estimation device 1, an access point 2, and wireless nodes (wireless devices) 3 (3a to 3e). Position estimation system 1000 is assumed to be used, for example, in stores and offices. As an example, FIG. 1 shows a wall surface 4 and product shelves 5a and 5b in addition to the position estimation system 1000, assuming that the position estimation system 1000 is used in a store, which is the target area. A wireless node 3 is shown arranged on a floor plan in the store.

A position estimation device 1 performs wireless communication with a wireless node 3 via an access point 2 and estimates the position of a moving wireless node 3e. Details of the configuration of the position estimation device 1 will be described later with reference to FIG.

The access point 2 performs wireless communication with the wireless node 3 according to the instruction of the position estimation device 1 and transmits the reception data from the wireless node 3 to the position estimation device 1 . Details of the configuration of the access point 2 will be described later with reference to FIG.

The wireless node 3 performs wireless communication with the access point 2 . Details of the configuration of the wireless node 3 will be described later with reference to FIG.

The wireless node 3 (3a-3e) includes an anchor node A (A1-A4) and a target node (third wireless device) T. Here, an anchor node is a wireless node fixed at a predetermined position. A target node is a wireless node whose position is to be estimated. In the example shown in FIG. 1, there are four anchor nodes A, A1 to A4, but the number of anchor nodes A may be any number of two or more.

In the example shown in FIG. 1, wireless nodes 3 (3a-3d) are anchor nodes A (A1-A4), respectively. The wireless node 3a (anchor node A1) is placed on the shelf 5a, the wireless node 3b (anchor node A2) is placed on the shelf 5b, and the wireless node 3c (anchor node A3) is placed on the wall 4 on the left side. 3d (anchor node A4) are installed on the lower wall surface 4, respectively.

On the other hand, in the example shown in FIG. 1, the target node T is the wireless node 3e moving on the path.

A dotted line connecting the access point 2 and the target node T and a dotted line connecting the target node T and the anchor nodes A1 to A4 shown in FIG. 1 respectively indicate arrival routes of radio signals. For example, if the target node T transmits a radio signal to the access point 2, this radio signal also reaches the anchor nodes A1-A4, and each anchor node A1-A4 can receive the radio signal. When receiving a radio signal, the reception level of the radio signal differs among the respective anchor nodes A1 to A4 due to differences in arrival routes, and the pattern composed of the reception level of the radio signal is at the position of the target node T. Varies accordingly.

Here, a pattern composed of a plurality of reception levels of radio signals transmitted from one of the radio nodes 3 and received by a plurality of other radio nodes 3 is called a fingerprint. As mentioned above, the fingerprint changes depending on the target node T's location. Therefore, in order to estimate the position of the target node T, fingerprints are collected prior to position estimation in a range (for example, a passage) in which the target node T may move. Next, when the target node T transmits a radio signal, the position of the target node T is estimated by pattern matching the reception levels at the anchor nodes A1 to A4 with previously collected fingerprints.

In the example shown in FIG. 1, the number of anchor nodes A1-A4 is four. Here, as the number of anchor nodes increases, the accuracy of estimating the position of the target node T improves, but the installation of the anchor nodes and the estimation of the position are costly. Therefore, where and how many anchor nodes should be installed to sufficiently estimate the position of the target node T is considered.

Further, the lower the correlation between the fingerprints obtained for each position of the target node T in the range where the target node T may move, the easier the identification of the fingerprints becomes. However, it takes a lot of time and cost to measure while changing a huge number of combinations of the target node T and the anchor node A in order to determine the installation location of the anchor node where the correlation between the fingerprints becomes low.

Solutions to the above points will be described later with reference to FIGS. 5 to 11. FIG.

FIG. 2 shows an example of the configuration of the position estimation device 1 according to the present disclosure. The position estimation device 1 includes a control section (control circuit) 11 , a storage section (storage circuit) 13 , and a communication section (communication device) 15 .

The control unit 11 controls the operation of the position estimation device 1 when determining the anchor node used for estimating the position of the target node and when estimating the position of the target node using the determined anchor node. The control unit 11 includes a target node position estimation unit (estimation circuit) 12 , a wireless node selection unit (selection circuit) 14 , and an anchor node determination unit (determination circuit) 16 .

The target node position estimation unit 12 reads the fingerprint from the storage unit 13 and estimates the position of the target node T when estimating the position of the target node. The read fingerprint is the fingerprint collected when the anchor node A is determined.

The storage unit 13 stores the fingerprint collected from the anchor node A when the anchor node A is determined. The stored fingerprint may be updated upon determination of the anchor node A.

The wireless node selection unit 14 selects a wireless node to be communicated with when the anchor node A is determined and when the position of the target node T is estimated.

The communication unit 15 communicates with the access point 2 . The communication unit 15 can communicate with the wireless node 3 via the access point 2 . The communication is wired communication via a wired communication medium or wireless communication via a wireless communication medium that does not interfere with wireless communication between the access point 2 and the wireless node 3 . The communication protocol used by the communication unit 15 is, for example, a serial communication protocol, a USB (Universal Serial Bus) protocol, or an Ethernet (registered trademark) protocol.

The anchor node determination unit 16 determines the anchor node A based on the fingerprints collected from the wireless nodes when the anchor node A is determined. Further, the anchor node determination unit 16 stores the fingerprint collected from the anchor node A in the storage unit 13. FIG.

FIG. 3 shows an example configuration of an access point 2 according to the present disclosure.

The access point 2 includes a communication section (communication device) 21 , a control section (control circuit) 22 , an RSSI measurement section (measurement circuit) 23 , and a radio communication section (radio communication device) 24 .

The communication unit 21 communicates with the position estimation unit 1 . The communication is wired communication via a wired communication medium or wireless communication via a wireless communication medium that does not interfere with wireless communication between the access point 2 and the wireless node 3 .

The control unit 22 controls the communication unit 21 and the wireless communication unit 24 to receive data indicating the wireless node 3 to be communicated from the position estimation device 1 and to send a call packet to the wireless node 3 to be communicated. and receive a response packet from the wireless node 3 . Furthermore, the control unit 22 controls the communication unit 21 and the RSSI measurement unit 23 to measure the RSSI of the communication with the wireless node 3 and transmit data indicating the measurement result to the position estimation device 1 .

The RSSI measurement unit 23 measures the reception level of the radio signal from the radio node 3 received by the radio communication unit 24 and converts it into RSSI. The RSSI measurement unit 23 may further perform various conversions such as conversion to dB units, predetermined scale conversion, linear approximation, and curve approximation to the RSSI.

The wireless communication unit 24 performs wireless communication with the wireless node 3 . Wireless communication includes, for example, low-power communication using the 920 MHz band, IEEE802.15.4, Zigbee using the 2.4 GHz band, Bluetooth (registered trademark), wireless LAN (IEEE802.11b/g/n), wireless LAN using the 5 GHz band ( IEEE802.11a/ac) or DSRC, wireless LAN (IEEE802.11ad) using the 60 GHz band, local PHS, or wireless communication using LTE.

FIG. 4 shows an example configuration of a wireless node 3 according to the present disclosure.

The wireless node 3 includes a wireless communication unit (wireless communication device) 31 , an RSSI measurement unit (measurement circuit) 32 , and a control unit (control circuit) 33 .

The wireless communication unit 31 performs wireless communication with the access point 2 . The wireless communication method is the same as the wireless communication method used by the access point 2 .

The RSSI measurement unit 32 measures the reception level of the radio signal from the access point 2 received by the radio communication unit 31 and converts it into RSSI. The RSSI measurement unit 32 may further perform various conversions such as conversion to dB units, predetermined scale conversion, linear approximation, and curve approximation to the RSSI.

The control unit 33 controls the wireless communication unit 31 to perform wireless communication with the access point 2 and intercept wireless signals from other wireless nodes 3 . Furthermore, the control unit 33 controls the RSSI measurement unit 32 to cause the RSSI measurement unit 32 to convert the reception level of the radio signal into RSSI.

The control unit 33 includes an RSSI management unit (management circuit) 34 . The RSSI management unit 34 saves the RSSI of another wireless node 3 intercepted by the wireless communication unit 31 and the transmission source as a reception history. In response to a request from the access point 2 , the control unit 33 controls the wireless communication unit 31 to notify the access point 2 of the RSSI history saved by the RSSI management unit 34 .

[Determination of anchor node]
In order to determine the anchor node A to be used for estimating the position of the target node T, for each radio node 3 placed within the range of movement of the target node T, each radio installed at a candidate position to install the anchor node A RSSI to and from node 3 is measured.

FIG. 5 shows an example arrangement of candidate positions C1-C20 and reference positions P1-P16 during anchor node determination according to the present disclosure.

The target area shown in FIG. 5 is the same as the target area shown in FIG. Candidate positions C1 to C20 indicate candidate positions where the anchor node A is installed. Reference positions P1 to P16 indicate positions to be referenced within the range in which the target node T moves. In the example shown in FIG. 5, the number of candidate positions C1 to C20 is 20, and the number of reference positions P1 to P16 is 16. is any number of

At the time of fingerprint measurement, wireless nodes 3 are arranged at all positions of candidate positions C1 to C20 and reference positions P1 to P16. For example, in the example shown in FIG. 5, a total of 36 wireless nodes 3 are installed at 20 candidate positions C1-C20 and 16 reference positions P1-P16.

The candidate positions C1 to C20 of the anchor node A are preferably positions that are easy to install, and are preferably arranged so as to be distributed as evenly as possible within the target area. Further, the reference positions P1 to P16 of the target node T may be arranged densely in a range where the detailed position of the target node T is desired, and sparsely in other ranges.

The wireless nodes 3 located at the reference positions P1 to P16 are hereinafter referred to as position nodes (first wireless devices) P1 to P16. Also, the wireless nodes 3 arranged at the candidate positions C1 to C20 are called candidate nodes (second wireless devices) C1 to C20.

FIG. 6 is a flowchart illustrating an example of operations when determining an anchor node according to the present disclosure.

In steps S603 to S605, the position estimation device 1 collects the fingerprints generated by the position nodes P1-P16 by instructing the access point 2. FIG.

First, in step S603, the wireless node selection unit 14 selects one of the position nodes P1 to P16 (for example, P1). Next, the radio node selection unit 14 causes the selected position node P1 to transmit a radio signal and transmits the radio signal to the candidate nodes C1 to C20 in order to measure the RSSI between the position node P1 and the candidate nodes C1 to C20. receive. Candidate nodes C1 to C20 intercept this radio signal, measure the RSSI, and store the ID of the transmitted position node and the measured RSSI value in the storage unit 13 as a reception history.

Next, in step S604, the anchor node determination unit 16 calls the candidate nodes C1 to C20 and collects reception histories of radio signals intercepted by the candidate nodes C1 to C20 from the position node P1.

FIG. 7 shows an example of the radio signal sequence in steps S603 and S604 when determining the anchor node.

In FIG. 7, AP represents access point 2, P1-PM position nodes P1-PM, and C1-CN candidate nodes C1-CN, respectively. Here, M and N are each an integer of 2 or more.

First, the access point 2 transmits a packet REQ (P1, AP) for calling the location node P1 by radio signal. Here, the packet REQ (P1, AP) is a packet whose destination is the position node P1 and whose source is the AP. Packet REQ(P1, AP) is received by all radio nodes 3 . The location node P1 whose destination in the packet REQ(P1, AP) matches its own ID responds.

The location node P1 sends a response packet ACK(AP, P1) to the AP by radio signal. The candidate nodes C1 to CN intercept the response packet ACK(AP, P1) and store the source ID and RSSI as a reception history.

For example, the candidate node C1 saves the source ID 'P1' and the RSSI value ' _r1,1 ' by intercepting the response packet ACK(P1, AP) sent by the location node P1. Similarly, the candidate node CN stores the source ID 'P1' and the RSSI value 'r _N,1 '.

By repeating the above procedure from the position node P1 to the position node PM, the candidate nodes C1 to CN store the reception history of the position nodes P1 to PM.

After receiving the response packet ACK (AP, PM) from the location node PM, the access point 2 calls the candidate nodes C1 to CN in order. First, for the candidate node C1, the access point 2 transmits a packet REQ (C1, AP) by radio signal in order to request notification of the reception history to the candidate node C1. In response to the received packet REQ (C1, AP), the candidate node C1 sends a response packet ACK (AP, C1) including the reception history (r _1,1 , . . . , r _M,1 ) saved up to that point. Transmit by radio signal. Then, by repeating the same procedure from candidate node C2 to candidate node CN, access point 2 collects all reception histories. The access point 2 transmits the reception history to the position estimation device 1 .

Again, refer to FIG. In step S605, the anchor node determining unit 16 determines whether or not all RSSIs between the position nodes P1 to P16 and the candidate nodes C1 to C20 have been measured. If it is determined that all have not been measured (step S605: No), the process returns to step S603. If it is determined that all have been measured (step S605: Yes), in step S606, the anchor node determining unit 16 selects the position of the anchor node from the candidate nodes C1 to CN based on the reception history.

FIG. 8A shows an example of the RSSI matrix RC. The anchor node determination unit 16 first generates the RSSI matrix RC shown in FIG. 8A based on the reception history received from the AP. Next, based on the RSSI values of the radio signals between the reference positions P1 to P20 and the candidate positions C1 to C20, the anchor node determination unit 16 creates a row vector in which the RSSI values between the reference positions P1 to P20 are arranged. A combination of candidate positions C1 to C20 with low correlation (large variation) is obtained (FIG. 8B). The anchor node determining unit 16 selects a combination of the obtained candidate positions C1 to C20 as the position where the anchor node A is to be installed. By removing all wireless nodes 3 placed at positions other than the selected position, the placement of the anchor node A suitable for position estimation within the target area is obtained.

In the above example, the position nodes P1 to P16 are called in this order in order to cause the position nodes P1 to P16 to transmit radio signals in step S603. Also, in step S604, the candidate nodes C1 to C20 were called in this order to collect reception histories. However, the calling order is not limited to the above example.

As the number M of position nodes P1 to PM increases and the number N of candidate nodes C1 to CN increases, the number of combinations between nodes increases to M×N. Due to the memory length of the reception history held by each wireless node 3 and the limitation of the packet length for transmitting the reception history, it may be difficult to transmit all reception histories at once. Also, if it is difficult to correctly demodulate each packet temporarily due to changes in the propagation environment, it is conceivable that some elements of the RSSI matrix RC may be missing at the access point 2 .

Therefore, in one example, the wireless node selection unit 14 may randomize the calling order of the wireless nodes 3 . For example, the wireless node selection unit 14 may rearrange the IDs of all the wireless nodes 3 at random and make calls in order based on the rearranged list of IDs. After going through the list of IDs, the wireless node selection unit 14 may randomly rearrange the IDs in the list again. Further, this may be repeated until all elements of the RSSI matrix RC are obtained.

In one example, the wireless node selector 14 may preferentially call a combination of wireless nodes 3 for which no reception history has been obtained. For example, when the RSSI when the wireless node 3i receives the signal transmitted by the wireless node 3j is ri _,j , the wireless node selection unit 14 selects ri, _{j that does not overlap with the already acquired r i,j} as much as possible _. A wireless node 3 having a large number _{of j} in its reception history may be called preferentially.

For example, the wireless node selection unit 14 extracts combinations of wireless nodes 3 for which r _i,j has not yet been acquired from the RSSI matrix RC. Next, the wireless node selection unit 14 selects r _i,j having, as the wireless node 3 j on the transmitting side, the wireless node 3 included in the list of the wireless nodes 3 called up to that point, as the next available r _i,j and Next, the wireless node selection unit 14 randomly selects the wireless node 3 to be called next from the I wireless nodes 3 having the largest number of obtainable r _i,j . Here, I is an arbitrary integer greater than or equal to 1.

By determining the calling order of the wireless nodes 3 as described above, r _i,j can be collected efficiently while the number of combinations of wireless nodes 3 whose r _i,j has not yet been obtained is large. Furthermore, the calling order may be switched before the number of combinations of wireless nodes 3 for which r _i,j has not been acquired decreases and the calling order becomes random and the collection efficiency drops. For example, when the number of unacquired r _i,j falls below a predetermined threshold, the calling order may be switched as follows. First, a call is made to the wireless node 3j for r _i,j that has not yet been acquired, and the wireless node 3i intercepts. Next, by calling the wireless node 3i, the unacquired r _i,j is acquired.

By selecting the calling order of the wireless nodes 3 in this manner, RSSIs can be collected efficiently even when the number of wireless nodes 3 is large and the number of combinations among the wireless nodes 3 is enormous. .

FIG. 8B shows an example of fingerprint matrix RA.

The RSSI matrix RC, which is generated by arranging the collected RSSIs in a matrix, includes the RSSIs for each of the reference positions P1 to PM in column vectors. Each element of the column vector is the RSSI value at the candidate positions C1-CN. For example, by selecting a combination of rows (that is, a combination of the candidate positions C1 to CN) that maximizes the variance of the row vectors of the RSSI matrix RC, the correlation between the column vectors can be reduced, and the reference positions P1 to PM can be easily identified.

In other words, position estimation of the reference positions P1 to PM (target nodes) can be performed by using the fingerprint matrix RA in FIG. 8B without using all the RSSI matrix RC shown in FIG. 8A. Therefore, not all of the candidate positions C1 to CN are necessary, and some of the candidate positions C1 to CN can be determined as anchor positions. A specific example of the processing will be described later with reference to FIGS. 9A to 11. FIG.

A fingerprint matrix RA is generated by selecting a combination of such elements and retrieving the corresponding row vectors. For example, here K candidate positions are extracted and the row vectors are concatenated into a K×M matrix. As shown in FIG. 8B, new indexes 1 to K are given in the row direction. Anchor nodes A1 to AK correspond to each row.

When estimating the position of the target node, the target node position estimating unit 12 calculates a fingerprint column vector r=(r1, ^. Generate. where T represents transposition. Next, the target node position estimator 12 compares the fingerprint column vector r=(r1,...,rK) ^T with each column vector of the fingerprint matrix RA, and the reference positions P1 to PM is assumed to be the position of the target node T. Details of the operation when estimating the position of the target node will be described later with reference to FIGS. 12 to 14. FIG.

[Concrete example]
A specific example is shown below to explain the operation of the position estimation device 1 when determining the anchor node. In order to simplify the explanation, the four anchor nodes A1 to An example of selecting A4 is shown.

FIG. 9A shows a specific example of RSSI values of radio signals transmitted by position node P2 and intercepted by candidate nodes C1-C20. FIG. 9B shows a specific example of RSSI values of radio signals transmitted by position node P8 and intercepted by candidate nodes C1-C20. FIG. 9C shows specific examples of RSSI values of radio signals transmitted by position node P14 and intercepted by candidate nodes C1-C20.

Here, the positions in the tables shown in FIGS. 9A-9C correspond to the positions of the candidate nodes shown in FIG. 5, and the RSSI values are arranged in 5 rows vertically and 4 columns horizontally. For example, the RSSI values of radio signals intercepted by candidate node C1 are the upper left corner values in the tables shown in FIGS. 9A-9C, which are 60, 50, and 50, respectively. Also, the RSSI values of the radio signals intercepted by candidate node C20 are the values in the lower right corner in the tables shown in FIGS. 9A-9C, which are 50, 50, and 50, respectively.

RSSI values may be normalized. For example, an average value (time average) of RSSI values measured multiple times may be used as the RSSI value. Also, the RSSI value is obtained by subtracting the average RSSI value (spatial average) of all candidate nodes C1 to C20 from the RSSI value of each candidate node C1 to C20 so as to take relative values among the candidate nodes C1 to C20. may be used as Also, the RSSI value may be weighted based on the transmission power of each of the position nodes P2, P8, P14.

FIG. 10 shows a specific example of data representing the RSSI matrix in a table format.
Each column vector of the RSSI matrix shown in table form in FIG. 10 is obtained by rearranging the RSSI values in the tables shown in FIGS. 9A to 9C in the vertical direction. The RSSI values in the tables shown in FIGS. 9A-9C are respectively placed in the first, second, and third columns of the RSSI matrix shown in FIG.

To generate a fingerprint matrix from the RSSI matrix shown in tabular form in FIG. 10, first, for each row (corresponding to each candidate node C1 to C20) of the RSSI matrix, a value indicating the variation of the RSSI values is calculated. . Here, the value indicating the variation is, for example, variance or standard deviation.

A row with a greater variation in RSSI value represents a better difference between the position nodes P2, P8, and P14, and the corresponding candidate nodes C1 to C20 are more suitable as anchor nodes. Therefore, for example, the anchor node determination unit 16 obtains the standard deviation σ for each row of the RSSI matrix, and selects the top K rows (for example, , K=4) (eg candidate nodes C7, C12, C4, C15).

Note that the anchor node determination unit 16 may obtain the standard deviation σ for each row of the RSSI matrix without using the threshold th, and select candidate nodes corresponding to the top K rows of the standard deviation σ. Alternatively, if the number of rows with the standard deviation σ equal to or greater than the threshold th is less than K rows, the anchor node determination unit 16 determines the candidate nodes corresponding to the rows of less than K rows, that is, the candidate nodes of less than K may be selected. Alternatively, if there are less than K rows with a standard deviation σ greater than or equal to the threshold th, after adding a new candidate node or after repositioning a candidate node with a lower RSSI value, The flow chart shown in FIG. 6 may be executed again to re-measure the radio signal between the location node and the candidate node.

FIG. 11 shows a specific example of data representing the fingerprint matrix in table format.
The anchor node determination unit 16 arranges the rows corresponding to the candidate nodes C7, C12, C4, and C15 selected as described above from the RSSI matrix shown in table form in FIG. Generate a fingerprint matrix. Candidate nodes C7, C12, C4, and C15 correspond to anchor nodes A1 to A4, respectively.

[Position estimation of target node]
FIG. 12 shows an example in which four anchor nodes A1 to A4 are selected in step S606 when determining anchor nodes.

12, among the candidate positions C1 to C20 shown in FIG. 5, the anchor node A1 is at the candidate position C7, the anchor node A2 is at the candidate position C12, the anchor node A3 is at the candidate position C4, and the anchor node A4 is at the candidate position C15. , respectively.

Anchor nodes A1 to A4 that are suitable for estimating the closest reference position to the target node T when the target node T is moving on the passage by the operation of the position estimation device 1 when determining the anchor nodes described above. are obtained as shown in FIG. The operation of the position estimation device 1 when estimating the position of the target node T using the anchor nodes A1 to A4 shown in FIG. 12 will be described below.

FIG. 13 is a flow chart showing an example of operations during position estimation by the position estimation device 1 according to the present disclosure.

First, in step S1103, in order to measure the RSSI between the target node T and the anchor nodes A1 to AK, the wireless node selection unit 14 causes the target node T to transmit a wireless signal and the anchor nodes A1 to AK to transmit the wireless signal. receive. Here, K is any integer greater than or equal to 2 and less than or equal to the number of candidate nodes. The anchor nodes A1 to AK intercept this radio signal, measure the RSSI, and store the measured RSSI value in the storage unit 13 as a reception history.

Next, in step S1104, the target node position estimation unit 12 calls the anchor nodes A1 to AK and collects reception histories of radio signals intercepted from the target node T by the anchor nodes A1 to AK.

FIG. 14 shows an example of a radio signal sequence in steps S1103 and S1104 during position estimation.

In FIG. 14, AP represents access point 2, T represents target node T, and A1 to AK represent anchor nodes A1 to AK.

The access point 2 transmits a packet REQ(T, AP) calling the target node T by radio signal. The target node T, whose destination in the packet REQ(T, AP) matches its own ID, responds to this.

The target node T transmits a response packet ACK(AP,T) to the access point 2 by radio signal. Anchor nodes A1 to AK intercept the response packet ACK(AP, T) and store the source ID and RSSI as a reception history.

After receiving the response packet ACK(AP,T) from the target node T, the access point 2 calls the anchor nodes A1 to AK in order. First, the access point 2 transmits a packet REQ (A1, AP) by radio signal to request the anchor node A1 to notify the reception history. In response to the received packet REQ (A1, AP), the target node A1 transmits a response packet ACK (AP, A1; r1) including the reception history (r1) saved up to that point by radio signal.

By repeating the above procedure from anchor node A1 to anchor node AK, access point 2 collects all reception histories (r1, . . . , rK). The access point 2 transmits the reception history (r1, . . . , rK) to the position estimation device 1. FIG.

Please refer to FIG. 13 again. In step S1105, the target node location estimation unit 12 determines whether or not all RSSIs between the target node T and the anchor nodes A1 to AK have been measured. If it is determined that all have not been measured (step S1105: No), the process returns to step S1103 to measure RSSI that has not been measured. If it is determined that all have been measured (step S1105: Yes), the target node position estimation unit 12 estimates the position of the target node T in step S1106.

The target node position estimation unit 12 generates a fingerprint column vector r=(r1,...,rK) ^T generated by transposing the reception history (r1,...,rK) received from the access point 2, as shown in FIG. 8B. The closest reference position is estimated by comparing with each column vector of the fingerprint matrix RA provided. That is, the target node position estimation unit 12 obtains m0 represented by the following equation (1), and estimates the position of the position node Pm0 corresponding to m0 as the position of the target node T.

但し、ＲＡ_・，ｍ＝（ｒ_１，ｍ，ｒ_２，ｍ，…，ｒ_Ｋ，ｍ）^Ｔであり、Ｔは転置を表す。ノルムは、例えば、Ｌ１ノルム、Ｌ２ノルム、またはＬ∞ノルムである。

However, RA _·,m = (r _1,m ,r _2,m ,...,r _K,m ) ^T , where T represents transposition. The norm is, for example, the L1 norm, the L2 norm, or the L∞ norm.

According to the present disclosure, radio signals transmitted by M location nodes Pm are simultaneously intercepted by N candidate nodes Cn. Also, the N candidate nodes Cn collectively transmit the RSSI values of the radio signals transmitted by the M position nodes Pm into one ACK packet. Therefore, even though the number of combinations of M position nodes Pm and N candidate nodes Cn increases by order O(M×N), the rate of increase is greater than order O(M×N) at maximum. RSSI values can be collected in a time period in which , increases in loose order O(M)+O(N). Therefore, even if M and N are large and the number of combinations is large, compared to the method of measuring the RSSI value while changing the combination of the target node T and the anchor node A, the good target node in the target area The time and cost required to determine the placement of the anchor node A to ensure T's location estimation performance can be reduced.

Further, according to the present disclosure, in a range where the target node T may move, the correlation between the fingerprints obtained for each position of the target node T is low, so that the candidate node C to the anchor node A selected. Therefore, it is possible to secure good position estimation performance of the target node T while reducing the number of anchor nodes A to be installed and the cost.

(Other embodiments)
In the above embodiment, the candidate nodes C1-CN intercept the radio signals transmitted by the position nodes P1-PM, and the candidate nodes C1-CN measure the RSSI values of the radio signals. Alternatively, an embodiment in which the relationship of transmission and reception is exchanged, that is, the radio signals transmitted by the candidate nodes C1 to CN are intercepted by the position nodes P1 to PM, and the position nodes P1 to PM measure the RSSI values of the radio signals. An embodiment is also conceivable. In this case, when determining anchor node A, in step S603 shown in FIGS. Send a packet REQ (Cn, AP).

Also, in step S604 shown in FIGS. 6 and 7, the access point 2 sends a packet REQ (Pm, AP) to the location node Pm instead of sending the packet REQ (Cn, AP) to the candidate node Cn. . Also, when estimating the position of the target node T, in step S1103 shown in FIGS. 13 and 14, the access point 2 sends k=1, , K each send a packet REQ(Ak, AP) to the anchor node Ak. Also, in step S1104 shown in FIGS. 13 and 14, for k=1, . Send packet REQ(T, AP) to .

Also, in the above-described embodiment, the access point 2 has the RSSI measuring section 23 . However, an embodiment in which the access point 2 does not have the RSSI measuring section 23 is also conceivable.

Various embodiments have been described above with reference to the drawings, but it goes without saying that the present disclosure is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present disclosure. Understood. Also, the components in the above embodiments may be combined arbitrarily without departing from the gist of the disclosure.

In each of the above-described embodiments, the present disclosure has been described as an example configured using hardware, but the present disclosure can also be realized by software in cooperation with hardware.

Also, each functional block used in the description of each of the above embodiments is typically implemented as an LSI, which is an integrated circuit. The integrated circuit may control each functional block used in the description of the above embodiments and may have inputs and outputs. These may be made into one chip individually, or may be made into one chip so as to include part or all of them. Although LSI is used here, it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Also, the method of circuit integration is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after LSI manufacturing, and a reconfigurable processor (Reconfigurable Processor) that can reconfigure connections or settings of circuit cells inside the LSI may be used.

Furthermore, if an integration technology that replaces LSI appears due to advances in semiconductor technology or another technology derived from it, the technology may naturally be used to integrate the functional blocks. Application of biotechnology, etc. is possible.

In the above description, the notation "... part" used for each component may be "... circuitry", "... device", "... unit", or "... Other notations such as "module" may be substituted.

(Summary of embodiment)
The position estimation device according to the present disclosure, based on the first reception strength of the first radio signals transmitted by the plurality of first radio devices, at the plurality of second radio devices, the plurality of second a determining circuit for selecting at least two of the wireless devices; and based on a second received strength of a second wireless signal transmitted by a third wireless device at said at least two selected second wireless devices. , and an estimation circuit for estimating the position of the third wireless device.

In the position estimation device according to the present disclosure, a signal for causing the plurality of first radio devices to transmit the first radio signal and a signal for causing the third radio device to transmit the second radio signal to an access point, and the access point wirelessly communicates with the plurality of first wireless devices, the plurality of second wireless devices, and the third wireless device.

In the position estimation device according to the present disclosure, the destination of the first radio signal and the second radio signal is the access point, and the plurality of second radio A signal and the second wireless signal are received.

In the position estimation device according to the present disclosure, the second wireless device transmits a response signal including information indicating the first reception strength or the second reception strength in response to a request from the access point. to an access point, and the decision circuit obtains information indicative of the first reception strength or the second reception strength from the access point.

In the position estimation device according to the present disclosure, the first received strength and the second received strength are indicated by an RSSI (Receive Signal Strength Indicator) value, and the determination circuit determines whether the plurality of second radio devices At least two of them are selected based on a value indicating variation in the RSSI value of the first radio signal received from the plurality of first radio apparatuses.

In the position estimation device according to the present disclosure, the value indicating the variation is a variance or a standard deviation, and the decision circuit receives from the plurality of first wireless devices among the plurality of second wireless devices K radio signals having large fluctuations in the RSSI value of the first radio signal are selected, where K is an integer of 2 or more.

In the position estimating device according to the present disclosure, the determination circuit is configured to obtain a value indicating variation in RSSI value of the first radio signal received from the plurality of first radio devices among the plurality of second radio devices. is greater than a predetermined threshold.

A wireless device according to the present disclosure includes a wireless communication device that intercepts a first wireless signal addressed to another wireless device, and a measurement circuit that measures the reception strength of the first wireless signal, wherein the wireless The communication device transmits a radio signal including information indicating the reception strength of the first radio signal, the radio communication device intercepts a second radio signal addressed to another radio device, and the measurement circuit measures the reception strength of the second radio signal, and the radio communication device transmits a radio signal including information indicating the reception strength of the second radio signal.

In the radio apparatus according to the present disclosure, the reception strength of the first radio signal and the reception strength of the second radio signal are indicated by RSSI (Receive Signal Strength Indicator) values.

A position estimation system according to the present disclosure includes a position estimation device according to the present disclosure, a wireless device according to the present disclosure, and an access point connected to the position estimation device and wirelessly communicating with the wireless device.

A position estimation method according to the present disclosure is based on a first reception strength of a first radio signal transmitted by a plurality of first radio devices at a plurality of second radio devices, selecting at least two of the wireless devices, and determining, based on a second received strength of a second wireless signal transmitted by a third wireless device at the at least two selected second wireless devices, Estimate the location of 3 wireless devices.

INDUSTRIAL APPLICABILITY The present disclosure can be applied to a position estimation system using fingerprints of wireless communication.

1000 position estimation system 1 position estimation device 2 access point 3 wireless nodes 11, 22, 33 control unit 12 target node position estimation unit 13 storage unit 14 wireless node selection units 15, 21 communication unit 16 anchor node determination units 23, 32 RSSI measurement Units 24 and 31 Wireless communication unit 34 RSSI management unit

Claims (10)

at least two of the plurality of second radio devices based on a combination of first reception strengths of the first radio signals transmitted by the plurality of first radio devices at the plurality of second radio devices a decision circuit to select;
selected from a combination of the second received strengths of the second radio signal transmitted by the third radio device and the combination of the first received strengths of the at least two selected second radio devices; estimating any one of the positions of the plurality of first radio devices as the position of the third radio device based on a combination of received strengths of the at least two second radio devices, and a circuit;
with
The first received strength and the second received strength are indicated by RSSI (Receive Signal Strength Indicator) values,
The decision circuit determines the at least two second selecting two wireless devices;
Position estimator. An output circuit for outputting to an access point a signal for causing the plurality of first wireless devices to transmit the first wireless signal and a signal for causing the third wireless device to transmit the second wireless signal. with
the access point wirelessly communicates with the plurality of first wireless devices, the plurality of second wireless devices, and the third wireless device;
The position estimation device according to claim 1. a destination of the first wireless signal and the second wireless signal is the access point;
the plurality of second radio devices receive the first radio signal and the second radio signal by interception;
The position estimation device according to claim 2. the second wireless device transmits a response signal including information indicating the first reception strength or the second reception strength to the access point in response to a request from the access point;
the decision circuit obtains information indicating the first reception strength or the second reception strength from the access point;
The position estimation device according to claim 3. The value indicating the variation is the variance or standard deviation,
The decision circuit selects, from the plurality of second radio apparatuses, K radio signals having large variations in RSSI values of the first radio signals received from the plurality of first radio apparatuses, where K is 2. is an integer greater than or equal to
The position estimation device according to claim 4 . The decision circuit selects, from among the plurality of second radio apparatuses, one having a value indicating variation in RSSI value of the first radio signal received from the plurality of first radio apparatuses greater than a predetermined threshold. do,
The position estimation device according to claim 4 or 5 . A radio device as a second radio device selected by the position estimation device according to any one of claims 1 to 6,
a wireless communication device that receives a first wireless signal transmitted by a first wireless device connected to an access point;
a measurement circuit that measures the reception strength of the first radio signal;
with
The wireless communication device transmits a wireless signal including information indicating the reception strength of the first wireless signal to the access point,
The wireless communication device receives a second wireless signal transmitted by a third wireless device,
The measurement circuit measures the reception strength of the second radio signal,
the wireless communication device transmits a wireless signal including information indicating the reception strength of the second wireless signal to the access point;
The access point is connected to the position estimation device according to any one of claims 1 to 6 ,
radio equipment. The received strength of the first radio signal and the received strength of the second radio signal are indicated by RSSI (Receive Signal Strength Indicator) values,
A wireless device according to claim 7 . A position estimation device according to any one of claims 1 to 6 ;
a wireless device according to claim 7 or 8 ;
an access point connected to the position estimation device and wirelessly communicating with the wireless device;
A position estimation system, comprising: at least two of the plurality of second radio devices based on a combination of first reception strengths of the first radio signals transmitted by the plurality of first radio devices at the plurality of second radio devices selection,
selected from a combination of the second received strengths of the second radio signal transmitted by the third radio device and the combination of the first received strengths of the at least two selected second radio devices; estimating any one of the positions of the plurality of first radio devices as the position of the third radio device, based on a combination of received strengths of the at least two second radio devices, and ,
The first received strength and the second received strength are indicated by RSSI (Receive Signal Strength Indicator) values,
The at least two second radio devices receive, among the plurality of second radio devices, the first radio signals received from the plurality of first radio devices, based on a value indicating variation in the RSSI value of the radio signal , selected,
Location estimation method.

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