Source: https://patents.google.com/patent/JP2014215134A/en
Timestamp: 2019-10-22 06:33:49
Document Index: 620319896

Matched Legal Cases: ['art 14', 'art 13', 'art 14', 'art 15', 'art 16', 'art 17', 'art 20']

JP2014215134A - Position estimation device, position estimation method, and radio communication system - Google Patents
Position estimation device, position estimation method, and radio communication system Download PDF
JP2014215134A
JP2014215134A JP2013091779A JP2013091779A JP2014215134A JP 2014215134 A JP2014215134 A JP 2014215134A JP 2013091779 A JP2013091779 A JP 2013091779A JP 2013091779 A JP2013091779 A JP 2013091779A JP 2014215134 A JP2014215134 A JP 2014215134A
JP2013091779A
カム リー グエン
方 連 佐
野 竜 馬 平
西 俊 之 中
2013-04-24 Application filed by 株式会社東芝, Toshiba Corp filed Critical 株式会社東芝
2013-04-24 Priority to JP2013091779A priority Critical patent/JP2014215134A/en
2014-11-17 Publication of JP2014215134A publication Critical patent/JP2014215134A/en
A position estimation error of a wireless device is reduced.
According to this embodiment, a position estimation device estimates a position of a target radio, and stores a position of a plurality of reference radios, the target radio and each reference radio. A receiving unit that is notified of a received power value in signal transmission / reception with a device, and using the received power value, a standard deviation of a probability distribution of a distance between the target wireless device and each reference wireless device A calculation unit that calculates, a first estimation unit that calculates an estimated distance between the target radio and each reference radio using the received power value, the standard deviation, the estimated distance, and the plurality of And a second estimation unit that calculates the position of the target wireless device using the position of the reference wireless device.
Embodiments described herein relate generally to a position estimation device, a position estimation method, and a wireless communication system.
Conventionally, a signal transmitted from a target radio whose position is unknown is received by a reference radio whose position is known, and a received signal strength indicator (RSSI) is obtained to estimate the position of the target radio. Has been done. Here, in estimating the position of the target wireless device, it is necessary to model the relationship between the distance between the wireless devices and the RSSI, and to calculate the distance between the wireless devices from the measured RSSI. However, since wireless communication is affected in various ways, RSSI may be different depending on time and environment even when the distances are equal. For this reason, it is difficult to estimate an accurate distance from the RSSI, and there is a problem that the estimation error of the position of the target radio is large.
Y. Wang, S. Shi, X. Yang and A. Ma, "Bluetooth indoor positioning using RSSI and Least Square estimation", 2010 second international conference on future computer and communications, September 2010.
An object of the present invention is to provide a position estimation device, a position estimation method, and a radio communication system that can reduce a position estimation error of a radio.
According to this embodiment, the position estimation device estimates the position of the target radio, and stores between the storage unit that stores the positions of a plurality of reference radios, the target radio, and each reference radio A receiving unit that is notified of a received power value in signal transmission / reception in the network, and a calculating unit that calculates a standard deviation of a probability distribution of a distance between the target radio and each reference radio using the received power value A first estimation unit that calculates an estimated distance between the target radio and each reference radio using the received power value, the standard deviation, the estimated distance, and the plurality of reference radios A second estimation unit that calculates the position of the target radio device using the position.
It is a schematic block diagram of the radio | wireless communications system by this embodiment. It is a schematic block diagram of the target radio | wireless machine by the embodiment. It is a schematic block diagram of the reference | standard radio | wireless machine by the embodiment. It is a schematic block diagram of the position estimation apparatus by the embodiment. It is a flowchart explaining the position estimation method by the embodiment. It is a schematic block diagram of the position estimation apparatus by a modification. It is a schematic block diagram of the radio | wireless communications system by a modification.
FIG. 1 is a schematic configuration diagram of a radio communication system according to the present embodiment. As shown in FIG. 1, the wireless communication system includes a position estimation device 10, a plurality of reference wireless devices 20, and a target wireless device 30. FIG. 1 shows an example in which three reference wireless devices 20A to 20C are arranged as a plurality of reference wireless devices 20.
The plurality of reference wireless devices 20 are wireless devices whose positions are known (determined) in advance, and the position estimation device 10 stores position information indicating the position of each reference wireless device 20. The position information of the reference wireless device 20 may be initially registered in the position estimating device 10, or the reference wireless device 20 notifies the position estimating device 10 of the position information of the own device based on a request from the position estimating device 10. May be.
The target wireless device 30 is a wireless device whose position is not grasped by the position estimation device 10 and the reference wireless device 20. In the present embodiment, the position estimation device 10 estimates the position of the target wireless device 30.
FIG. 2 is a schematic configuration diagram of the target radio device 30. As shown in FIG. 2, the target radio device 30 includes a transmission control unit 31, a transmission unit 32, and an antenna 33, and functions as a transmitter. A plurality of antennas 33 may be provided.
The transmission control unit 31 generates a transmission signal and controls the transmission unit 32 to transmit the transmission signal at a constant period. The transmission signal includes, for example, individual identification information of the target wireless device 30. The transmission unit 32 transmits a transmission signal via the antenna 33.
FIG. 3 shows a schematic configuration of the reference wireless device 20. As shown in FIG. 3, the reference radio device 20 includes a control unit 21, a receiving unit 22, a transmitting unit 23, and an antenna 24, and functions as a transceiver. A plurality of antennas 24 may be provided.
The receiving unit 22 receives a signal transmitted from the target radio 30 via the antenna 24, and measures a received power value (Received Signal Strength Indicator, hereinafter referred to as RSSI). The control unit 21 controls the transmission unit 23 so as to notify the position estimation device 10 of RSSI measured by the receiving unit 22, the individual identification information of the target wireless device 30, the individual identification information of the own device, and the like. The transmission unit 23 transmits the RSSI, the individual identification information of the target wireless device 30, and the individual identification information of the own device to the position estimation device 10 via the antenna 24.
In addition, although the example in which the reference wireless device 20 and the position estimation device 10 are wirelessly connected has been described in FIG. 3, the reference wireless device 20 and the position estimation device 10 may be wiredly connected by a LAN cable or the like.
FIG. 4 shows a schematic configuration of the position estimation apparatus 10. The position estimation device 10 includes an antenna 11, a reception unit 12, a control unit 13, a storage unit 14, a standard deviation calculation unit 15, a distance estimation unit 16, and a position estimation unit 17. The receiving unit 12 receives the measurement RSSI, the individual identification information of the target wireless device 30, and the individual identification information of the reference wireless device 20 from the reference wireless device 20 via the antenna 11. For example, when the received signal of the receiving unit 12 includes the measurement RSSI, the individual identification information of the target radio 30, and the individual identification information of the reference radio 20 </ b> A, the reference radio 20 </ b> A receives the target radio. It can be seen that this is the RSSI of the signal received from the machine 30.
When the position estimation apparatus 10 receives the measurement RSSI of the transmission signal from the target radio 30 from the plurality of reference radios 20, the position estimation apparatus 10 estimates the position of the target radio 30 by a method described later.
The control unit 13 controls each unit of the position estimation device 10. Further, when the receiving unit 12 receives the position information from the reference wireless device 20, the position information is written in the storage unit 14.
In estimating the distance d between the reference wireless device 20 and the target wireless device 30 from the measured RSSI in the reference wireless device 20, the probability distribution of the distance d can be regarded as following a normal distribution (Gaussian distribution).
For example, by averaging the change in RSSI with time change, frequency change, or movement, the fluctuation in RSSI can be reduced, and the position estimation accuracy of the target radio device 30 can be increased. Therefore, as described above, it can be assumed that the probability distribution of the distance d between the radios when RSSI is given follows a normal distribution.
When the RSSI is measured in the reference wireless device 20, the probability distribution of the distance d between the reference wireless device 20 and the target wireless device 30 is expressed by a probability density function as shown in Equation 1 below.
Here, when the estimate is the estimated distance between the reference wireless device 20 and the target wireless device 30, that is, when RSSI is measured, the distance between the wireless devices has the highest probability of becoming the destroy . σ (RSSI) is the standard deviation of the distance relative to the measured RSSI. In the present embodiment, the standard deviation σ (RSSI) of the distance in the probability distribution of the distance d is a variable that changes according to the measured RSSI, and is not a constant. The standard deviation calculation unit 15 of the position estimation device 10 calculates the standard deviation σ (RSSI) of the distance in the probability distribution of Equation 1 based on the measured RSSI notified from the reference wireless device 20 for each of the plurality of reference wireless devices 20. Is calculated. A method for calculating the standard deviation of the distance will be described later.
The distance estimation unit 16 calculates the estimated distance de estimate in Equation 1 for each of the plurality of reference radio devices 20. A method for calculating the estimated distance d estimate will be described later.
Based on the standard deviation of the distance calculated by the standard deviation calculator 15, the estimated distance de estimate calculated by the distance estimator 16, and the position of the known reference radio 20, the position estimator 17 The position of is calculated. A method of calculating the position of the target wireless device 30 by the position estimation unit 17 will be described later.
Next, the position estimation method according to the present embodiment will be described with reference to the flowchart shown in FIG.
(Step S101) The target wireless device 30 transmits a signal.
(Step S <b> 102) The plurality of reference wireless devices 20 receive the signal transmitted from the target wireless device 30 and measure RSSI.
(Step S103) The plurality of reference radio devices 20 notify the position estimation apparatus 10 of the RSSI measured in Step S102.
(Step S104) The standard deviation calculation unit 15 of the position estimation apparatus 10 calculates the standard deviation σ of the distance in the probability distribution of Equation 1 based on the RSSI notified from the reference wireless device 20 for each of the plurality of reference wireless devices 20. (RSSI) is calculated.
The RSSI and the distance d between the radio devices can be expressed by, for example, an expression representing a path loss shown in the following Expression 2. In Equation 2, α is an attenuation constant, and β is the average RSSI when the distance d is 1 meter.
One example for obtaining α and β is the following method. First, in various environments such as indoors and outdoors, radios are arranged at two locations to transmit and receive signals and measure RSSI. Then, while changing the arrangement of the radio m times (m is a positive integer) performs RSSI measurements, obtaining the distance d k between the radios, the combination data (d k, RSSI k) the RSSI k of actual measurement of the To do. Here, k is an integer of 1 to m. Fit d k and RSSI k to Equation 2 to calculate parameters α and β.
However, even if the distance d is the same, the RSSI may vary due to factors such as multipath and shadowing. In other words, the distance d may be different even if the RSSI value is the same. Therefore, in this embodiment, it is assumed that the standard deviation of the probability distribution of the distance d differs according to the RSSI value, and the standard deviation calculator 15 calculates the standard deviation σ (RSSI) of the distance.
For example, RSSI is actually measured by transmitting and receiving signals in advance by arranging two wireless devices in various environments such as indoors and outdoors and in various positions. For example, while changing the arrangement of the radio m times (m is a positive integer) performs RSSI measurements, obtaining the distance d k between the radios, the combination data (d k, RSSI k) the RSSI k of actual measurement of the To do. Here, k is an integer of 1 to m. Then, the acquired data is sliced into a plurality of groups based on the RSSI value, and the dispersion of the distance in each slice is obtained from Equation 3 below.
Here, RSSI rep, j is a representative RSSI value of the j-th RSSI slice. A set of indexes of data included in the slice can be defined as in Equation 4 below, where Δ is the slice width.
The number of indexes included in Φ (RSSI rep, j ) is expressed by the following Equation 5.
Moreover, the average value of distance is shown by the following numerical formula 6.
The standard deviation σ (RSSI rep, j ) and RSSI rep, j of the distance obtained using Equations 3 to 6 are plotted on coordinates to derive an approximate curve (function). Thus, the approximate curve derived | led-out previously is memorize | stored in the memory | storage part 14, for example.
The distance standard deviation calculation unit 15 inputs the RSSI notified from the reference wireless device 20 to the above approximate curve, and calculates the standard deviation of the distance. For example, the standard deviation calculation unit 15 inputs the RSSI notified from the reference wireless devices 20A to 20C to the approximate curve, and calculates the standard deviation of the corresponding distance for each of the reference wireless devices 20A to 20C.
(Step S < b > 105) The distance estimation unit 16 calculates an estimated distance de estimate between the reference wireless device 20 and the target wireless device 30 from the RSSI notified from the reference wireless device 20. The estimated distance d estimate can be obtained from the equation representing the path loss shown in Equation 2. Specifically, the RSSI notified from the reference wireless device 20 is input to the following Equation 7 to calculate the estimated distance de estimate .
For example, the distance estimation unit 16 inputs the RSSI notified from the reference wireless devices 20A to 20C to Equation 7, and calculates the estimated distance de estimate for each of the reference wireless devices 20A to 20C.
(Step S106) The position estimation unit 17 calculates the position of the target wireless device 30. The position estimation unit 17 calculates the position where the likelihood function is the largest using the standard deviation of the distance obtained in step S104 and Equation 1 as the position of the target wireless device 30.
RSSI measured by the n reference wireless devices 20 are RSSI1, RSSI2,... RSSIn, and the positions of the n reference wireless devices 20 are (x 1 , y 1 ), (x 2 , y 2 ),. .., (X n , y n ), the position (x, y) of the target wireless device 30 is expressed by the following Equation 8. n is an integer of 2 or more, and i is an integer of 1 to n.
Here, the distance d i between the target wireless device 30 and the reference wireless device 20 at the position (x i , y i ) is expressed by Equation 9 below.
Substituting Equation 8 into Equation 1 yields Equation 10 below.
Here, σ i is the standard deviation of the distance corresponding to the reference wireless device 20 at the position (x i , y i ), and the one calculated in step S104 is used. Further, deestimate_i is an estimated distance deestimate corresponding to the reference wireless device 20 at the position (x i , y i ), and is calculated in step S105.
In Equation 10, when the log of both sides is taken, the following Equation 11 is obtained.
Since the second term on the right side of Equation 11 is a constant, the following Equation 12 is obtained.
The position estimation unit 17 gives σ i and de estimate_i in Equation 12, and calculates the position (x, y) of the target radio 30 using an optimization method such as the steepest descent method. Thereby, the position of the target wireless device 30 is obtained.
As described above, according to the present embodiment, the standard deviation calculation unit 15 of the position estimation apparatus 10 is based on the RSSI measured by the reference radio device 20 and the distance in the probability distribution of the inter-radio device distance d shown in Equation 1. Calculate the standard deviation of. By setting the standard deviation of the distance according to the situation, the position of the target wireless device 30 can be obtained with high accuracy and the position estimation error can be reduced.
In the above embodiment, the standard deviation σ (RSSI rep, j ) and RSSI rep, j of the distance are plotted on the coordinates to derive the approximate curve. However, the standard deviation of the distance is calculated by fitting to the exponential function. An exponential function may be obtained. As shown in Equation 2, RSSI is a logarithmic function of distance d. In other words, distance d is an exponential function of RSSI. Therefore, the standard deviation of the distance d can be expressed as an exponential function of RSSI.
Specifically, the distance standard deviation σ (RSSI rep, j ) and RSSI rep, j are fitted to the exponential function shown in the following Equation 13 to obtain the optimum values of the parameters a and b.
The standard deviation calculation unit 15 can calculate the standard deviation of the distance by inputting the RSSI notified from the reference wireless device 20 to the above-described exponential function.
FIG. 6 shows a block configuration of the position estimation apparatus 10 according to a modification. As shown in FIG. 6, a plurality of standard deviation calculation units 15 and distance estimation units 16 corresponding to a plurality of reference radio devices 20 are provided, and the distance standard deviation σ (RSSI) and the radio devices for the corresponding reference radio devices 20 are provided. The inter-estimated distance d estimate may be calculated in parallel.
FIG. 1 shows an example in which three reference wireless devices 20A to 20C are provided in the wireless communication system. However, in order to estimate the position of the target wireless device 30 in the two-dimensional space, three or more positions are required. A known reference radio 20 is provided. When estimating the position of the target wireless device 30 in the one-dimensional space, it is sufficient that two or more reference wireless devices 20 are provided. When estimating the position of the target radio 30 in the three-dimensional space, four or more reference radios are provided.
In the above embodiment, the reference radio device 20 receives the signal transmitted from the target radio device 30 and measures RSSI. However, as shown in FIG. 7, the signal transmitted from the reference radio device 20 is the target. The radio 30 may receive and measure RSSI. In this case, the reference radio device 20 has a configuration as shown in FIG. 2, and the target radio device 30 has a configuration as shown in FIG. The target wireless device 30 notifies the position estimation device 10 of the measured RSSI. The position estimation device 30 can calculate the position of the target wireless device 30 by the same method as in the above embodiment.
In the above embodiment, the reference radio device 20 does not need to be fixed, and may be movable as long as the position is known.
The position estimation device 10 may be integrated with the reference wireless device 20 or the target wireless device 30.
In the above embodiment, an example in which the storage unit 14 stores mathematical formulas (approximate curves and exponential functions) for calculating the standard deviation of the distance from the RSSI notified from the reference radio device 20 has been described. 14 may store a table indicating the relationship between the RSSI and the standard deviation of the distance. In this case, the standard deviation calculation unit 15 refers to the table stored in the storage unit 14 and obtains the standard deviation of the distance from the RSSI notified from the reference wireless device 20.
DESCRIPTION OF SYMBOLS 10 Position estimation apparatus 11 Antenna 12 Reception part 13 Control part 14 Storage part 15 Standard deviation calculation part 16 Distance estimation part 17 Position estimation part 20 Reference | standard radio | wireless machine 30 Target radio | wireless machine
A position estimation device for estimating a position of a target radio,
A storage unit for storing the positions of a plurality of reference wireless devices;
A receiving unit that is notified of a received power value in signal transmission and reception between the target wireless device and each reference wireless device;
Using the received power value, a calculation unit that calculates a standard deviation of a probability distribution of the distance between the target radio and each reference radio;
A first estimation unit that calculates an estimated distance between the target radio and each reference radio using the received power value;
A second estimation unit that calculates the position of the target radio using the standard deviation, the estimated distance, and the positions of the plurality of reference radios;
A position estimation apparatus comprising:
The storage unit stores a relationship between a received power value and a standard deviation,
The said calculation part calculates the said standard deviation corresponding to each reference | standard radio | wireless from the notified received power value and the relationship between the said received power value and a standard deviation. Position estimation device.
The position estimation apparatus according to claim 2, wherein the relationship between the received power value and the standard deviation is an exponential function in which the received power value becomes an index.
The position estimation apparatus according to claim 1, wherein the reception unit is notified of a reception power value from the reference wireless device.
The position estimation apparatus according to claim 1, wherein the reception unit is notified of a reception power value from the target wireless device.
Estimated distance d estimate between the target radio and the reference radio, the RSSI of the received power value at the transmission and reception of signals between the target radio and the reference radio, the attenuation constant alpha, radio The received power value when the inter-distance is 1 meter is β, and the first estimating unit calculates the estimated distance de estimate using the following formula: 6. A position estimation device according to claim 1.
The probability distribution P (d | RSSI) of the distance d between the target wireless device and the reference wireless device is expressed by the following formula, where σ (RSSI) is the standard deviation calculated by the calculation unit. The position estimation apparatus according to claim 6.
The second estimation unit sets the distance between the target radio and the i-th reference radio (i is an integer) to d i, and the i-th reference radio calculated by the calculation unit to σ i in the following equation: fed a standard deviation corresponding to the machine, given the estimated distance d estimate corresponding to the i reference radio calculated by the first estimating portion d Estimate_i, calculating the position of the target wireless device (x, y) The position estimation apparatus according to claim 7, wherein:
A position estimation method for estimating a position of a target radio that communicates with a plurality of reference radios whose positions are known,
Obtain a received power value in signal transmission / reception between the target radio and each reference radio,
Using the received power value, calculate the standard deviation of the probability distribution of the distance between the target radio and each reference radio,
Using the received power value, calculate an estimated distance between the target radio and each reference radio,
A position estimation method for calculating the position of the target radio using the standard deviation, the estimated distance, and the positions of the plurality of reference radios.
Multiple reference radios,
A target radio that communicates with the plurality of reference radios;
A position estimation device for estimating the position of the target radio;
The position estimation device includes:
A storage unit for storing positions of the plurality of reference wireless devices;
JP2013091779A 2013-04-24 2013-04-24 Position estimation device, position estimation method, and radio communication system Pending JP2014215134A (en)
JP2013091779A JP2014215134A (en) 2013-04-24 2013-04-24 Position estimation device, position estimation method, and radio communication system
US14/197,906 US20140320348A1 (en) 2013-04-24 2014-03-05 Position estimating device, position estimating method, and wireless communication system
JP2014215134A true JP2014215134A (en) 2014-11-17
ID=51788791
JP2013091779A Pending JP2014215134A (en) 2013-04-24 2013-04-24 Position estimation device, position estimation method, and radio communication system
US (1) US20140320348A1 (en)
JP (1) JP2014215134A (en)
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