JP6185804B2 - Determination device, network node, determination method, and program - Google Patents

Description

  The present invention relates to a position estimation technique for a mobile device.

  There is a fingerprint positioning method as a method for specifying the position of a mobile communication device in a multipath environment or a non-line-of-sight environment (see Patent Document 1). In this method, a parameter that can be a fingerprint is acquired in a device whose position is known in advance, and a database is constructed by storing the parameter in association with the position. Specifically, for example, for a wide geographical area, at many known positions (reference positions), feature quantities of radio signals from a plurality of fixed communication devices such as base stations are observed in advance, and Information on the observed value, the transmission source communication device, and the reference position is stored in the database. Note that the feature amount of the radio signal here is, for example, radio wave propagation loss, received signal strength indication (RSSI), or the like.

  In the fingerprint positioning method, for example, an observation value of a radio signal in a mobile device is acquired via a base station, and pattern matching with information stored in a database is performed, so that the mobile communication device's The position is estimated. In the fingerprint positioning method, the value related to the feature value of the wireless signal at the reference position is stored in advance as a fingerprint in this way. Are compared to estimate the position of the mobile device to be determined.

  In the fingerprint positioning method, a plurality of reference positions are grouped for each region, the reference positions belonging to some groups are specified, and the reference values corresponding to the reference positions and the observation values in the mobile device are There is a method to compare. In this method, first, for each group, a reference value corresponding to a reference position representing the group is compared with an observed value observed by the mobile device, and a reference position having a reference value close to the observed value is obtained. A group having a representative is specified. Thereafter, the reference value at the reference position belonging to the specified group is compared with the observed value in the mobile device, and the detailed position of the mobile device is specified. As a result, only the reference values corresponding to some reference positions are compared with the observed values without comparing with the observed values for the reference values corresponding to all the reference positions stored in the database. The amount of calculation related to positioning can be greatly reduced.

Special table 2012-512404 gazette

  On the other hand, even if reference positions are grouped, the number of groups is extremely large in a wireless communication system that covers a wide geographical area. Therefore, there is a problem that the amount of calculation increases due to the comparison between the reference value corresponding to the reference position representing each group and the observed value in the mobile device.

  The present invention has been made in view of the above problems, and an object of the present invention is to estimate the position of a mobile device while suppressing the amount of calculation in a fingerprint positioning method.

In order to achieve the above object, the determination device according to the present invention provides a plurality of communication devices, each of which is a radio signal from a plurality of communication devices whose positions are fixed and each of the observed values in the mobile device and the plurality of reference positions. A determination device for determining a position of the mobile device by comparing a reference value of an observation value obtained by observing and storing a radio signal from each of the wireless signals in advance, including a position where the mobile device exists Is estimated based on the direction of arrival of signals at each of a plurality of base stations, acquisition means for acquiring, and based on the geographical region, In the determination of the position of the mobile device, a specifying means for specifying at least one reference position to be compared, the reference value at the at least one reference position, and the mobile device Having a determination means for determining the position of the mobile device by comparing the observed value.

  According to the present invention, in the fingerprint positioning method, the position of the mobile device can be estimated while reducing the amount of calculation.

1 is a diagram illustrating an example of a wireless communication system. The conceptual diagram which shows the area | region where a mobile terminal is anticipated to exist. The figure which shows the function structural example of a position determination apparatus. The figure which shows the hardware structural example of a position determination apparatus. The flowchart which shows the flow of the position determination process of the mobile terminal which a position determination apparatus performs.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Wireless communication system)
FIG. 1 shows a wireless communication system according to this embodiment. The wireless communication system is a system based on a cellular network, for example, and includes a base station A, a base station B, a base station C, and a mobile terminal. In the wireless communication system, there is a position determination device connected to the base station A, the base station B, and the base station C via a network. In the following, the position determination device is described as a network node independent of the base stations A to C, but the position determination device may be provided in these base stations. In this example, a system including three base stations and one mobile terminal will be described for the sake of simplification. However, four or more base stations may exist, and two or more base stations may exist. It is clear that a mobile terminal may be present.

  A mobile terminal is a wireless communication device that can move and has an indefinite position. The mobile terminal transmits or receives a radio signal to / from at least one of the base station A to the base station C. Base station A to base station C are fixed wireless communication apparatuses, and communicate with mobile terminals within their communicable range (cell). In the present embodiment, the feature amount of the radio signal transmitted from the base station A to the base station C and observed at each position is used as a fingerprint, and the position of the mobile terminal is determined.

  FIG. 1 further shows a plurality of reference positions used for determining the position of the mobile terminal by the position determination device. In FIG. 1, the reference position is indicated by a black circle. In the present embodiment, feature quantities of radio signals from a plurality of base stations are observed in advance at a reference position and stored in a database. The feature amount of the radio signal includes, for example, radio wave propagation loss, signal received power (Reference Signal Received Power, RSRP), signal-to-interference and noise power ratio (SINR), and the like. Further, the database may exist in the position determination apparatus, may exist as a network node different from the position determination apparatus, or may exist in the base station. Here, the feature amount of the radio signal observed for each of the plurality of reference positions is stored as a distribution represented by, for example, a value indicating the feature amount and a frequency (ratio) at which the value occurs. Note that the feature value of the radio signal may be expressed as an average value of feature values, a median value of the above-described distribution, or a mode value.

  The observation of the feature quantity of the radio signal at the reference position is executed by, for example, a mobile terminal having a GPS positioning function or an A-GPS positioning function. In this case, the positioning result by the GPS positioning function or the A-GPS positioning function is used as a reference position, and the observed value of the feature value of the radio signal at the reference position is stored in the database as the reference value of the observed value. In this case, the mobile terminal cannot always be observed at the same position. For this reason, for example, the geographical area may be divided into areas of 5 m square, for example, and the data observed in one area may be handled as being observed at the same place. That is, a distribution may be generated by collecting feature quantities observed in a 5 m square area, and one point in the area may be used as a reference position, and the distribution may be stored in a database in association with the reference position. .

  The mobile terminal observes the feature quantity of the radio signal from each of the base station A to the base station C, and uses the feature quantity information as base station information (for example, cell) of the radio signal corresponding to the feature quantity. ID) and a base station (for example, serving base station) with which connection is established. Note that the mobile terminal may observe the feature quantity of the radio signal for a certain period, accumulate the feature quantity information, and then notify the base station of the accumulated information. The base station notified of the information transfers this information to the position determination device.

  And based on the information notified from the mobile terminal, the position determination device generates a distribution based on the value indicating the feature amount of the radio signal in the mobile terminal and the frequency (ratio) at which the value occurred, The distribution is compared with the distribution stored corresponding to the reference position. Then, for example, the position determination device estimates the position of the mobile terminal based on the reference position corresponding to the distribution having the highest correlation with the distribution of the feature amount of the radio signal in the mobile terminal. That is, for example, the position determination device determines that the mobile terminal is present at the reference position corresponding to the distribution having the highest correlation with the distribution of the feature amount of the radio signal in the mobile terminal.

  The position determination device, for example, compares the feature quantity observed by the mobile terminal with the reference value represented by the average value, the median value, or the mode value of the feature quantity previously observed at the reference position. May be. In this case, for example, the position determination device compares the feature amount of the signal from each of the base stations A to C observed by the mobile terminal and the reference value at each reference position. Then, for example, the position determination device calculates the difference between the feature value and the reference value for each of the base stations A to C, and specifies the reference position corresponding to the reference value having the smallest sum of absolute values. , It is determined that the mobile terminal exists at the specified reference position.

  In such a positioning method, the accuracy of positioning can be improved because the reference position exists in a wide range. On the other hand, if the reference position is set finely in order to improve the positioning accuracy, the reference position to be compared in the determination of the position of the mobile terminal becomes enormous, the calculation amount becomes large, and the position can be specified. Takes a long time to complete. Further, even if the reference positions are grouped, if the number of groups increases, a large amount of calculation is required to compare the reference value related to the reference position that is a representative of the group and the observed value at the mobile terminal. .

  For this reason, in the present embodiment, the position determination device first acquires a geographical region that is expected to include the position where the mobile terminal is present. Note that the position determination device can acquire this geographical area by estimating using, for example, a call log recorded when the base station communicates with the mobile terminal.

  For example, the position determination device can calculate the distance between the mobile terminal and the base station from the propagation delay (radio wave arrival time) between the mobile terminal and the base station, measured at the mobile terminal or each base station. Is estimated. Note that the propagation delay is, for example, the result of subtracting the transmission time from the reception time when the transmission device transmits a signal including the transmission time, the reception device receives the signal, and measures the reception time. Can be obtained. In addition, the transmission side device measures the time (round trip time) from when a signal is transmitted until it receives a response signal from the reception side device to that signal. The propagation delay can be estimated by reducing the processing time in the device and dividing by two. The distance between the base station and the mobile terminal can be estimated by multiplying the propagation delay by the speed of light. At this time, the estimated distance between the base station and the mobile terminal may deviate from the actual distance due to reflection or diffraction in the propagation path. Therefore, the position determination device estimates a geographical region where the mobile terminal is expected to exist by adding an error to the estimated distance. A geographical area where a mobile terminal is expected to exist will be described with reference to FIG.

In FIG. 2, the distances (l _{A to} l _C ) are estimated based on the propagation delay for each of the mobile terminal and the base stations A to _C. At this time, distance errors e _{A to} e _C from each base station are given. For example, the error is small when the distance is considered to be calculated with high accuracy based on the value indicating the calculation accuracy of the distance, and the error is large when the calculation accuracy is low. The value may be fixed. At this time, the mobile terminal is expected to exist in the range of distance l _A −e _{A to} l _A + e _A when viewed from the base station A. Similarly, when viewed from the base station B, the mobile terminal is expected to exist in the range of distance l _B −e _{B to} l _B + e _B. Further, the mobile terminal is expected to exist in the range of distance l _C −e _{C to} l _C + e _{C when} viewed from the base station C. As a result, a range satisfying all of these is a region painted with diagonal lines in FIG. Therefore, the position determination apparatus can acquire this area as an area where the mobile terminal is expected to exist.

  The estimation of the geographical area may be performed by the mobile terminal. In this case, the position estimation device receives information on the geographical area from the mobile terminal via the base station and the network. Will be acquired. Further, in the above description, by estimating the distance between each base station and the mobile terminal from the propagation delay, a geographical region where the mobile terminal is expected to be present is estimated in consideration of an error. Explained the case. However, the method for acquiring the geographical area is not limited to this. For example, the position where the mobile terminal is expected to exist may be specified by trilateral survey from the difference in arrival times of signals from the mobile terminal in a plurality of base stations. In addition, in a plurality of base stations, the arrival direction of a signal from a mobile terminal may be observed, and a position where the mobile terminal is expected to exist may be specified based on the arrival direction. In these cases, the geographical area where the mobile terminal is expected to exist can be estimated by a circle having a radius corresponding to the added error centered on the identified point. Similarly, when GPS or A-GPS positioning is performed in a mobile terminal, it is expected that the mobile terminal exists by a circle having a radius corresponding to an error corresponding to the positioning level centered on the position of the positioning result. Can be estimated. Further, the geographical area where the mobile terminal is expected to exist may be specified by the cell or sector deployed by the base station to which the mobile terminal is connected.

  After that, the position determination device specifies the reference position included in the acquired geographical area, extracts it from the database, the reference value of the feature value of the radio signal corresponding to the reference position, and the feature value of the radio signal in the mobile terminal Compare with the observed values and perform fingerprint positioning.

  As a result, first, it is possible to execute positioning that is allowed to be coarse by a positioning method with a small amount of calculation, and to narrow down reference positions to be compared in fingerprint positioning based on the positioning result. As a result, the amount of calculation in fingerprint positioning can be reduced, the total amount of calculation can be reduced, and the position of the mobile terminal can be determined by high-precision fingerprint positioning.

  Next, the configuration and processing of the position determination device according to this embodiment will be described.

(Functional configuration of position determination device)
FIG. 3 is a block diagram illustrating a functional configuration example of the position determination device. The position determination apparatus includes, for example, an information acquisition unit 301, a prior positioning unit 302, a comparison target specifying unit 303, a reference position information database (DB) 304, a position determination unit 305, and a position information output unit 306 as its functions.

  The information acquisition unit 301 acquires, for example, a call log remaining when communication with a mobile terminal is performed from each base station. The call log includes an identifier of a mobile terminal that has communicated, a communication time, and a feature amount of a signal (radio wave) received by the mobile terminal at the time of communication. Here, the feature amount is, for example, an identifier of a base station around the mobile terminal such as a base station (serving base station) that communicated with the mobile terminal or its adjacent base station, and a radio wave propagation loss for each base station. , Received signal strength (RSSI, RSRP), SINR, and the like. The information acquisition unit 301 passes the acquired information to the prior positioning unit 302.

  Note that the information acquisition unit 301 may acquire a GPS positioning result at a communication time corresponding to the log together with a call log from a mobile terminal having a GPS positioning function, for example. In this case, the information acquisition unit 301 may associate the GPS positioning result and the feature amount information included in the call log and store them in the reference position information DB 304 as a reference value. Further, the GPS positioning result and the positioning level may be passed to the pre-positioning unit 302, and the pre-positioning unit 302 may identify a geographical region that is expected to include the position where the mobile terminal exists from these pieces of information. .

  Based on the call log received from the information acquisition unit 301, the prior positioning unit 302 executes prior positioning of the position of the mobile terminal for specifying a reference position to be compared in fingerprint positioning. This positioning includes, for example, positioning by estimating the propagation delay amount of radio waves, positioning by specifying a base station to which the mobile terminal is connected, as described above. For example, when the call log includes propagation delay information, the prior positioning unit 302 performs positioning using the propagation delay information. Further, the preliminary positioning unit 302 may perform preliminary positioning, for example, using a cell or sector deployed by a base station (serving base station) to which the mobile terminal is connected during communication. The prior positioning unit 302 identifies a geographical region that is expected to include a position where the mobile terminal is present according to the result of such prior positioning, and passes the identification result to the comparison target identifying unit 303.

  The comparison target specifying unit 303 is a target of comparison with the feature amount observed by the mobile terminal in the fingerprint positioning among the reference positions stored in the reference position information DB 304 based on the geographical region specified by the prior positioning unit 302. At least one reference position is specified. In addition, when the reference position is grouped, the comparison target specifying unit 303 specifies the group to which the reference position included in the geographical area specified by the prior positioning unit 302 belongs, and then the reference position belonging to the specified group May be specified. In this case, the comparison target specifying unit 303 extracts all the reference positions belonging to the specified one or more groups, and is a reference to be compared with the feature amount observed by the mobile terminal in the fingerprint positioning. You may specify as a position. In this case, for example, when one group corresponds to a certain area and the area includes the geographical area specified by the prior positioning unit 302, the group including the reference position not included in the geographical area is included. All the reference positions belonging to are specified as reference positions to be compared. Further, even if the reference positions are grouped, only the reference positions included in the geographical area specified by the prior positioning unit 302 are specified as the reference positions used in the fingerprint positioning, regardless of the group. May be.

  The reference position information DB 304 is a distribution indicating, for example, a reference position, an average value of feature values of radio signals from each base station observed at the reference position, and a frequency range in which the value is included. Or the median or mode of the distribution is stored in advance as a reference value. The reference position is specified by, for example, latitude and longitude information. In addition, the reference position may be determined as, for example, a region divided into 5 m square small regions and the center point or an arbitrary point in the small region. At this time, in the reference position information DB 304, when the observed value of the feature value of the radio signal is input together with the GPS positioning result included in a certain small area, all of the observed values are observed at the center point of the small area. The feature value or distribution may be generated and stored. The reference position information DB 304 may group a plurality of reference positions by dividing them into regions. In this case, for example, each of the plurality of reference positions belongs to any one of a plurality of groups. The reference position information DB 304 specifies, for example, the base station that is the transmission source of the radio signal that is most strongly received at each of the plurality of reference positions based on, for example, the average value of feature values or the distribution of feature values. A plurality of reference positions may be grouped according to the base stations that have been selected. In this case, grouping is generally performed in units of cells developed by each base station.

のように計算する。ここで、Ｐは判定に用いる基地局の個数である。ここで、複数の基地局のそれぞれが送信した信号について、受信点において観測された特徴量の分布が存在する。このため、上述の式は、複数の基地局についてそれぞれ存在する分布のうち、Ｐ個の基地局についての分布のみを判定において考慮することを示す。Ｐは１以上の整数である。Ｊは、例えば、参照位置情報ＤＢ３０４に記憶される分布における、特徴量（例えばＲＳＲＰ）の値域の個数である。例えば、分布において、全体で３０ｄＢｍの幅を１ｄＢｍの幅で区切って、その区切られた区間（値域）に含まれる特徴量が生じた度数をカウントした場合は、Ｊ＝３０となる。また、ρ_i,p,jは、ｉ番目の参照位置についての、ｐ番目の基地局についての分布に関する、ｊ番目の値域に含まれる特徴量が生じた頻度（確率）を示す。また、ｒ_p,jは、測位対象の移動体端末における、ｐ番目の基地局からの無線信号の特徴量の観測値が、ｊ番目の特徴量の値域に含まれる確率を示している。 The position determination unit 305 obtains the feature value (reference value) of the received signal for the reference position specified by the comparison target specifying unit and the feature value of the radio signal from the base station observed at the positioning target mobile terminal. In comparison, the position of the mobile terminal is determined. Note that the observation value at the mobile terminal may be the result of observation at the mobile terminal after the start of positioning, or the call log described above. Here, a case where a distribution of feature values is used as the observed value and the reference value will be described. As described above, the distribution is expressed as a frequency (a value obtained by dividing the frequency by the number of samples) in which value range among the value ranges into which the feature value is divided. For example, when there are I reference positions, the position determination unit 305 determines the following d _i (1 ≦ i ≦ I) for each reference position:

Calculate as follows. Here, P is the number of base stations used for determination. Here, there is a distribution of feature quantities observed at the reception point for signals transmitted from each of the plurality of base stations. For this reason, the above formula indicates that only the distributions for P base stations are considered in the determination among the distributions existing for the plurality of base stations. P is an integer of 1 or more. J is, for example, the number of feature value (for example, RSRP) value ranges in the distribution stored in the reference position information DB 304. For example, in the distribution, when a total width of 30 dBm is divided by a width of 1 dBm and the frequency of occurrence of the feature amount included in the divided section (value range) is counted, J = 30. Further, ρ _{i, p, j} indicates the frequency (probability) that the feature amount included in the j-th range occurs with respect to the distribution for the p-th base station for the i-th reference position. Further, r _{p, j} indicates the probability that the observed value of the feature value of the radio signal from the p-th base station in the positioning target mobile terminal is included in the range of the j-th feature value.

The distribution of the feature quantity of the radio signal from each base station, which is generated in advance with respect to the reference position by the calculation of d _i described above, and the feature quantity of the radio signal from each base station observed at the positioning target mobile terminal It is possible to determine how different the distribution is. Then, the position determination unit 305 determines the reference position corresponding to the distribution with the smallest difference from the distribution observed at the mobile terminal as the position where the mobile terminal exists. That is, the position determination unit 305 determines i ₀ having the smallest value among the calculated I d _i (1 ≦ i ≦ I), and determines that the mobile terminal is present at the i ₀ th reference position. To do.

  The location information output unit 306 stores the determination result in a medium such as a database or a file, or notifies each base station (for example, a serving base station of a mobile terminal) via a network. The determination result may be notified to the mobile terminal. Further, the mobile terminal may notify the user by displaying the determination result on a display (not shown). For example, the mobile terminal may display an index for specifying its own position on the map application.

(Hardware configuration of position determination device)
For example, the position determination apparatus has a hardware configuration as shown in FIG. 4, and includes, for example, a CPU 401, a ROM 402, a RAM 403, an external storage device 404, and an input / output device 405. In the position determination device, for example, the CPU 401 executes a program that realizes each of the functions described above, which is recorded in any of the ROM 402, the RAM 403, and the external storage device 404. Then, using the input / output device 405, the position determination device acquires, for example, information on the observed value of the feature value at the mobile terminal from the network and outputs the position determination result to the network.

  Note that the position determination device may include dedicated hardware for executing the above-described functions, or may be executed by a computer that executes a part of the hardware and executes the program. Further, all the functions described above may be executed by a computer and a program.

(Position determination processing in the position determination device)
FIG. 5 shows the flow of the position determination process of the mobile terminal executed by the position determination apparatus. Here, it is assumed that the construction of the DB related to the reference position has already been completed.

  The position determination device first acquires a call log for a mobile terminal to be positioned (S501). Thereafter, the position determination device performs prior positioning of the mobile terminal based on the acquired call log (S502), and specifies a geographical region expected to include the position where the mobile terminal exists (S503). Thereafter, the position determination device specifies a reference position to be compared based on the specified geographical area (S504). Subsequently, the position determination device determines the position of the mobile terminal based on the identified reference position (S505).

  As described above, in the fingerprint positioning method, after specifying the approximate position of the mobile terminal in advance, it is possible to limit the reference position to be compared according to the result. As a result, since the reference position to be compared is limited, it is possible to reduce the calculation amount or processing time related to positioning.

Claims (6)

Observations of radio signals from a plurality of communication devices whose positions are fixed in a mobile device and observations in which radio signals from the plurality of communication devices are observed and stored in advance at each of a plurality of reference positions A determination device for comparing the reference value of the value to determine the position of the mobile device,
An acquisition unit that estimates and acquires a geographical region expected to include a position where the mobile device exists based on directions of arrival of signals in each of a plurality of base stations ;
A specifying unit that specifies at least one reference position to be compared in the determination of the position of the mobile device among the plurality of reference positions based on the geographical area;
Determining means for comparing the reference value at the at least one reference position with the observed value at the mobile device to determine the position of the mobile device;
The determination apparatus characterized by having. The specifying means specifies a reference position included in the geographical area as at least one reference position to be compared in the determination of the position of the mobile device;
The determination apparatus according to claim 1, wherein: The plurality of reference positions belong to one of a plurality of groups;
The specifying means specifies a group to which a reference position included in the geographical region belongs, and sets a reference position belonging to any of the specified groups as a comparison target in determining the position of the mobile device. Identify as one reference position,
Determination apparatus according to claim 1 or 2, characterized in that. Network node, characterized in that it comprises a determination device according to any one of claims 1 to 3. Observations of radio signals from a plurality of communication devices whose positions are fixed in a mobile device and observations in which radio signals from the plurality of communication devices are observed and stored in advance at each of a plurality of reference positions A determination method in a determination device that compares a reference value of a value to determine the position of the mobile device,
An acquisition step in which an acquisition unit estimates and acquires a geographical region expected to include a position where the mobile device exists based on arrival directions of signals in each of a plurality of base stations ;
A specifying step for specifying at least one reference position to be compared in the determination of the position of the mobile device among the plurality of reference positions based on the geographical area;
A determination step of determining a position of the mobile device by comparing the reference value at the at least one reference position with the observed value in the mobile device;
The determination method characterized by having. Observations of radio signals from a plurality of communication devices whose positions are fixed in a mobile device and observations in which radio signals from the plurality of communication devices are observed and stored in advance at each of a plurality of reference positions A computer provided in a determination device that compares the reference value of the value and determines the position of the mobile device,
An acquisition step of estimating and acquiring a geographical region expected to include a position where the mobile device is present based on an arrival direction of a signal in each of a plurality of base stations ;
A specifying step of specifying at least one reference position to be compared in the determination of the position of the mobile device among the plurality of reference positions based on the geographical area;
A determination step of determining the position of the mobile device by comparing the reference value at the at least one reference position with the observed value at the mobile device;
A program for running

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