JP2008256559A - Portable terminal and location system used for location - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the accuracy of location by preventing location from being performed with a location signal other than direct wave. <P>SOLUTION: In the portable terminal 300 for receiving a location signal and locating the own current position, a received signal intensity history 1200 of the location signal is recorded, and a moving history determined from a detection value of an acceleration sensor 318 or the like is recorded. A first free space loss is determined based on the received signal intensity of the received location signal, and an origin position as a position where the received signal intensity of the location signal becomes a maximum is determined based on the received signal intensity history 1200. The distance from the origin position to the current position is determined based on the origin position and the moving distance/direction history, a second free space loss of the location signal is determined based on the determined distance, and it is determined whether the received location signal is direct wave by comparing the first free space loss with the second free space loss. When it is not the direct wave, the location with the received location signal is not performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile terminal and a position location system used for position location, and more particularly to a technique for ensuring location accuracy.

For example, in Non-Patent Document 1, as a technique applied to an autonomous movement support system (pedestrian ITS) or the like, wireless signals are transmitted from a plurality of antennas installed in a base station to a portable terminal carried by a pedestrian, and each antenna The relative position between the mobile terminal and the antenna is obtained from the phase difference of the radio signal transmitted from the mobile station, and the current position of the pedestrian is obtained from the obtained relative position (direction, distance) and the absolute position of the base station. A location system is disclosed.
Takenori Takeuchi, Kiminori Kono, Minoru Kono, “Development of a location detection system using the 2.4 GHz band”, The 56th Annual Conference of the Chugoku Branch of the Institute of Electrical and Information Engineering, 2005

  In the above positioning system, it is assumed that the relative position is determined by a direct wave that reaches the mobile terminal from the antenna of the base station. Therefore, a radio signal other than the direct wave that reaches the mobile terminal from the base station by multipath or the like If the position location is performed by this, the orientation accuracy may be significantly lowered.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a position locating system and a control method thereof that can ensure the locating accuracy.

  A main invention for achieving the above object is a portable terminal used for position determination, a position determination signal receiving unit that receives a position determination signal that is a radio signal for determining its current position, and the position A position locating unit for locating its current position based on a locating signal, a circuit for obtaining a received signal strength of the locating signal, an acceleration sensor, a geomagnetic sensor, and a history of the received signal strength of the locating signal Based on detection values of the acceleration sensor and the geomagnetic sensor, and a received signal intensity history recording unit that generates a received signal intensity history recorded in association with the reception time of the position location signal. A movement distance / direction history recording unit that generates a movement distance / direction history in which a history is recorded in association with the acquisition time of the detection value, and the received signal of the received position location signal. A first free space loss calculation unit that obtains a first free space loss that is a free space loss of the received position location signal from the strength, and a received signal strength of the received position location signal from the received signal strength history is maximum. Based on the starting point setting unit for specifying the starting point time that is the most recent time from the current time, and the starting point time and the movement distance / direction history, from the own position at the starting point time to the own current position A travel distance calculating unit for determining a distance; a second free space loss calculating unit for determining a second free space loss that is a free space loss of the positioning signal based on the travel distance; the first free space loss; A free space loss comparison unit that compares the second free space loss and determines whether the received position location signal is a direct wave, and the position location unit includes the free space loss comparison But it is assumed that the position location signal when it is determined that it is not direct wave, so as not to perform position location according to said received position location signals.

  In the present invention, when the position location signal reaching the mobile terminal is a direct wave, it is determined whether the position location signal is a direct wave by utilizing the fact that the free space loss is minimized. That is, in the mobile terminal of the present invention, when locating its current position, the first free space loss, which is a free space loss obtained from the received signal strength of the received position location signal, and the acceleration sensor and the geomagnetic sensor By comparing the second free space loss that is the free space loss of the position location signal obtained from the obtained moving distance, it is determined whether the received position location signal is a direct wave or not. Do not perform location based on orientation signals. For this reason, it is possible to prevent the positioning from being performed by a radio signal other than the direct wave that reaches the mobile terminal from the base station by multipath or the like, and the positioning accuracy of the positioning system can be ensured.

  Note that the free space loss comparison unit determines that the received position location signal is not a direct wave when the difference between the first free space loss and the second free space loss is equal to or greater than a predetermined value, for example. Therefore, it is possible to determine whether or not the position location signal received with higher accuracy is a direct wave by setting the predetermined value to an appropriate value.

  According to the present invention, it is possible to ensure the positioning accuracy of the positioning system.

  Hereinafter, one embodiment of the present invention will be described in detail. FIG. 1 shows a schematic configuration of an autonomous movement support system 1 described as an embodiment of the present invention. The autonomous movement support system 1 provides route guidance to a support target person (moving person) such as a pedestrian, guidance to a destination, provision of regional information to the support target person, geography such as a current position and a movement direction of the support target person. Provide various services such as monitoring third-party information and ensuring the safety of the support target.

  The autonomous movement support system 1 includes a server device 100 installed in a data center 2 and the like, a plurality of base stations 200 installed in various places (electric pole 3 and the like) where the autonomous movement support system 1 is deployed, and a support target person 3 It is comprised including the portable terminal 300 carried by. The base station 200 is communicably connected to the server apparatus 100 via a wired or wireless communication network 50 such as a dedicated line or the Internet. The protocol of communication performed via the communication network 50 is, for example, TCP / IP, and a network address (for example, IP address) for performing communication via the communication network 50 is assigned to the server apparatus 100 and the base station 200. Has been.

  FIG. 2A shows a hardware configuration of the server apparatus 100. The server device 100 has a CPU 111, a memory 112, a hard disk 113, an input device 114 such as a keyboard and a mouse, a display device 115 such as a liquid crystal display, and a communication interface 116 for connecting to the communication network 50 and communicating with the base station 200. is doing. The CPU 111 implements various functions of the server device 100 by executing programs stored in the memory 112. The input device 114 receives user operation input. Information such as the current position and moving direction of the support target person 3 is displayed on the display device 115 in real time on the map screen. The communication interface 116 transmits / receives various information to / from the server device 100 and other base stations 200 via the communication network 50.

  FIG. 2B shows functions of the server device 100. The server device 100 collects information such as the current position of the mobile terminal 300 from the base station 200. Further, the server device 100 provides the guidance target information to the support target person 3, guidance to the destination, provision of geographical information about the current position, and support provided to a third party monitoring the support target person. The base station 200 is appropriately provided with information on the current position and moving direction of the target person, information on ensuring the safety of the support target person, and the like.

  In FIG. 2B, the information provision collection unit 121 performs information provision (download) to the base station 200 and information collection (upload) from the base station 200. The setting information storage unit 123 is information (hereinafter referred to as setting information) used when the base station 200 provides a function such as a position location function described later. The setting information includes the latitude, longitude, installation height, and the like of the base station 200.

  FIG. 3A shows the hardware configuration of the base station 200. The base station 200 includes a CPU 211, a memory 212, a communication interface 213, an antenna group 215, and the like. The CPU 211 executes programs stored in the memory 212 and realizes various functions provided in the base station 200. The communication interface 213 communicates with the server device 100 via the communication network 50. The wireless communication interface 214 transmits a wireless signal for position location described later. The antenna group 215 includes a plurality of circularly polarized directional antennas 2151 (see FIG. 8). The antenna group 215 is accompanied by a changeover switch 2152. The changeover switch 2152 selects any one of the antennas 2151 and connects to the wireless communication interface 214. Note that the CPU 211, the memory 212, the communication interface 213, and the antenna group 215 are connected to be communicable with each other via the bus 220.

  FIG. 3B shows a schematic function of the base station 200. The communication unit 261 transmits and receives various types of information to and from the server device 100 through the communication interface 213. The position location signal transmission unit 263 transmits a radio signal (hereinafter referred to as a position location signal) used to locate the current position of the mobile terminal 300. The setting information storage unit 264 stores the setting information described above.

  FIG. 4A shows a hardware configuration of the mobile terminal 300. As shown in the figure, the mobile terminal 300 includes a CPU 311, a memory 312, a wireless communication interface 313, an antenna 314, an input device 315 such as a touch panel and operation buttons, a display device 316 such as a liquid crystal display, a timer circuit 317, and an acceleration sensor 318. , A geomagnetic sensor 319 for detecting the direction of geomagnetism, and an RSSI circuit 216 (RSSI: Radio Signal Strength Indicator).

  The CPU 311 implements various functions of the mobile terminal 300 by executing programs stored in the memory 312. The timer circuit 317 generates / outputs the current time in response to a request from the CPU 311 or the like. The acceleration sensor 318 detects acceleration acting on the mobile terminal 300 and outputs a signal indicating the magnitude of the detected acceleration. The geomagnetic sensor 319 detects the direction of geomagnetism and outputs a signal indicating the detected direction. The RSSI circuit 320 generates / outputs a signal indicating the received signal strength of a radio wave such as a position location signal received by the wireless communication interface 313.

  FIG. 4B shows functions of the mobile terminal 300. In the figure, a position location signal receiver 331 receives a location signal transmitted from the base station 200 by the wireless communication interface 313. The information transmission / reception unit 332 communicates with the server apparatus 100 via the communication network 50 to receive (download) information to be presented to the support target person 3 and transmit (upload) various information used in the server apparatus 100. Do. The information display unit 333 outputs information to be presented to the support target person 3 to the display device 316. The position locating unit 334 determines the current position of the mobile terminal 300 based on the position locating signal received by the position locating signal receiving unit 331. The current position of the portable terminal 300 determined by the position determination is transmitted from the portable terminal 300 to the base station 200 by wireless communication, and is transmitted from the base station 200 to the server apparatus 100 via the communication network 50. Details of the processing related to position location will be described later. The direct wave determination unit 335 determines whether the position determination signal received by the position determination signal reception unit 331 is a direct wave or a reflected wave that reaches the mobile terminal 300 by multipath or the like.

  FIG. 5 shows details of the function of the direct wave determination unit 335. In the figure, a received signal strength history recording unit 3351 obtains the received signal strength of the positioning signal from the RSSI circuit 320 in real time, and obtains the received signal strength obtained from the timer circuit 317 at the current time (each received signal strength). In the memory 312 in association with the acquisition time). Hereinafter, the information recorded in the memory 312 at this time is referred to as a received signal strength history.

  The movement distance / direction history recording unit 3352 acquires the detection value of the acceleration sensor 318 at a predetermined interval, and obtains the movement distance of the mobile terminal 300 by integrating the acquired detection value twice. In addition, detection values of the geomagnetic sensor 319 are acquired at predetermined intervals, and the moving direction of the mobile terminal 300 is obtained based on the acquired detection values. Then, the movement distance / direction history recording unit 3352 stores the obtained movement distance and movement direction at predetermined intervals in the memory in association with the current time acquired from the timer circuit 317 (acquisition time of each acceleration and movement direction). To do. Hereinafter, the information recorded in the memory 312 at this time is referred to as a movement distance / direction history.

The first free space loss calculation unit 3353 obtains the free space loss of the positioning signal (hereinafter referred to as the first free space loss) from the received signal strength in the received signal strength history. The first free space loss is obtained when the signal strength S _{0 of the} positioning signal transmitted from the antenna 2151 of the base station 200 and the strength (reception signal strength) of the positioning signal received by the mobile terminal 300 are S ₁ . It is determined from the ratio of S ₁ and S ₀ (S ₁ / S ₀ ). The signal strength S ₀ is stored in advance in the memory 312 of the mobile terminal 300.

  The starting point setting unit 3354 specifies the time nearest to the current time when the received signal strength is maximum from the received signal strength history, and sets the time as the starting time to be referred to by the movement distance calculating unit 3355 described later.

  Based on the starting time and the moving distance / direction history set by the starting point setting unit 3354, the moving distance calculation unit 3355 starts from the position of the mobile terminal 300 at the starting time (hereinafter referred to as the starting point). The distance to the current position (movement distance) is obtained.

  The second free space loss calculation unit 3356 calculates a free space loss (hereinafter referred to as a second free space loss) of the received positioning signal based on the movement distance obtained by the movement distance calculation unit 3355. Note that the second free space loss when the absolute moving distance from the starting point is d and the wavelength of the positioning signal is λ is obtained by 20 logs (4πd / λ).

  The free space loss comparison unit 3357 compares the first free space loss and the second free space loss to determine whether the received position location signal is a direct wave or a reflected wave.

<Positioning system>
The position location mechanism of the mobile terminal 300 in the autonomous movement support system 1 is realized by the position location system 10 including the base station 200 and the mobile terminal 300 existing around the base station 200. Hereinafter, the position locating system 10 will be described in detail.

  The wireless communication interface 214 of the base station 200 transmits a spectrum-spread wireless signal while periodically switching a plurality of antennas 2151 constituting the antenna group 215. On the other hand, the positioning signal receiving unit 331 of the mobile terminal 300 receives a signal transmitted from each antenna 2151 of the base station 200 by the antenna 314. In order to prevent radio wave interference between adjacent base stations, each base station 200 shares a synchronization signal between the base stations 200, and controls so that a position location signal is not transmitted from the adjacent base stations 200 at the same time. Is going.

  FIG. 6 shows the data format of the position location signal transmitted from the base station 200. As shown in the figure, the position location signal includes the above-described synchronization signal 611, location code 612 (UCODE), antenna information 613, and measurement signal 614. The synchronization signal 611 is composed of a total of 48 bits of data including a 32-bit preamble signal and a 16-bit synchronization signal.

  The location code 612 (UCODE) is information for specifying the installation location of the base station 200. The place code 612 is a 128-bit code assigned to each position in accordance with the unified standard. The antenna information 613 includes the height of the antenna 2151, the identifier of the antenna 2151, 16-bit data indicating the directivity direction of the antenna 2151, and the like. The measurement signal 614 includes a signal for detecting the direction in which the mobile terminal 300 exists and the relative distance to the mobile terminal 300, and includes a 2048 chip spread code that is transmitted while sequentially switching the four antennas 2151 as the base points. .

  FIG. 7 shows the positional relationship between the base station 200 and the mobile terminal 300 at a site such as a sidewalk. In the figure, the mobile terminal 300 is present at a ground height 1 (m), and the base station 200 is installed at a ground height H (m). Further, the distance from directly below the base station 200 to the mobile terminal 300 is L (m).

  FIG. 8 shows the positional relationship between each antenna 2151 constituting the antenna group 215 and the portable terminal 300. Each antenna 2151 constituting the antenna group 215 of the base station 200 is installed with the directivity direction obliquely downward in the field. As shown in the figure, the antenna group 215 is arranged adjacent to each other in a substantially square shape at intervals of 3 cm (this interval corresponds to a quarter wavelength when a radio wave in the 2.4 GHz band is used as a positioning signal). And four circularly polarized directional antennas.

As shown in FIG. 8, when the angle formed by the horizontal direction at the height of the antenna group 215 and the direction of the mobile terminal 300 with respect to the antenna group 215 is α,
α = arcTan (D (m) / L (m)) = arcSin (ΔL (cm) / 3 (cm))
It becomes. In addition, ΔL (cm) is a propagation path length difference between two specific antennas 2151 of the antenna 2151 constituting the antenna group 215 and the mobile terminal 300.

Here, if the phase difference between the positioning signals transmitted from the two specific antennas 2151 constituting the antenna group 215 is Δθ, the ΔL is
ΔL (cm) = Δθ / 2π / λ (cm)
It becomes. For example, when a 2.4 GHz band radio wave is used as the position location signal, λ≈12 (cm).
α = arcSin (2Δθ / π)
It becomes. Further, since α = Δθ (radian) in the measurable range (−π / 2 <Δθ <π / 2), the direction in which the base station 200 exists can be specified from the above equation.

Next, a method for locating the position of the mobile terminal 300 using the above result will be described.
FIG. 9 shows the positional relationship between the base station 200 and the mobile terminal 300 in the field. As shown in the figure, an orthogonal coordinate axis with the ground height of the antenna group 215 of the base station 200 as H (m), the ground height of the mobile terminal 300 as h (m), and the position of the ground surface directly below the base station 200 as the origin. When (X axis, Y axis) is set, the angle formed by the direction from the base station 200 to the portable terminal 300 and the X axis is ΔΦ (x), and the direction from the base station 200 to the portable terminal 300 is formed by the Y axis. When the angle is ΔΦ (y), the position of the mobile terminal 300 with respect to the origin can be obtained from the following equation.
Δd (x) = (H−h) × Tan (ΔΦ (x))
Δd (y) = (H−h) × Tan (ΔΦ (y))
If the position of the origin is (X1, Y1), the current position (Xx, Yy) of the mobile terminal 300 is
Xx = X1 + Δd (x)
Yy = Y1 + Δd (y)
As required. Note that the positioning principle described above is described in detail in, for example, Japanese Patent Application Laid-Open Nos. 2004-184078, 2005-351877, 2005-351878, and 2006-23261. Has been.

<Positioning process>
Next, the current location determination process of the mobile terminal 300 performed by the location determination unit 334 of the mobile terminal 300 will be described. The current position locating process is appropriately executed according to the timing of reporting the position of the mobile terminal 300 to the server device 100, the operation performed by the user of the mobile terminal 300 on the input device 315, and the like.

  FIG. 10 is a flowchart for explaining the position location process (S1000). As shown in the figure, in the position determination process (S1000), first, the position determination unit 334 acquires the received signal strength of the position determination signal received from the RSSI circuit 320 by the position determination signal reception unit 331 (S1011). Next, the position locating unit 334 executes a process for determining whether the received position locating signal is a direct wave or a reflected wave (hereinafter referred to as a direct wave determination process) (S1012). Details of the direct wave determination process (S1012) will be described later.

  In subsequent S1013, the process is branched according to the result of the direct wave determination process (S1012). When the position determination signal is a direct wave (S1013: direct wave), the process proceeds to S1014, and the reflected wave If there is (S1013: reflected wave), the process proceeds to S1015.

  In S1014, the position locating unit 334 locates the current position based on the position locating signal by the method described above. On the other hand, in S1015, the position locating unit 334 causes the movement distance calculation unit 3355 of the direct wave determination unit 335 to be described later based on the movement distance / direction history recorded in the memory 312 by the movement distance / direction history recording unit 3352. The position is determined by processing based on values detected by the acceleration sensor 318 and the geomagnetic sensor 319. After the process of S1014 or S1015 is completed, the position location process (S1000) is terminated.

  As described above, the position locating unit 334 determines the current position using the position locating signal when the received position locating signal is a direct wave, and the acceleration sensor 318 and the geomagnetic sensor 319 when the received position locating signal is a reflected wave. The position is determined based on the detected value. For this reason, it is possible to prevent the position location from being performed by a radio signal other than the direct wave that reaches the mobile terminal 300 from the base station 200 by multipath or the like, and the position location accuracy of the position location system 10 can be ensured. it can.

  Next, details of the direct wave determination process (S1012) in the above-described position location process (S1000) will be described with reference to the flowchart shown in FIG. As shown in the figure, in the direct wave determination process (S1012), the first free space loss calculation unit 3353 first obtains the first free space loss corresponding to the received signal strength during reception (S1121). Next, the starting point setting unit 3354 identifies the latest time when the received signal strength is maximum from the received signal strength history, and sets that time as the starting time to be referred to by the movement distance calculating unit 3355 described later (S1122). .

  FIG. 12 shows an example of the received signal strength history 1200. In the received signal history shown in the figure, the most recent time when the received signal strength reaches the maximum (61 dBm), that is, the starting time is t1.

  Next, the moving distance calculation unit 3355 calculates the absolute moving distance of the mobile terminal 300 from the starting point to the current position based on the starting point time and the moving distance / direction history set by the starting point setting unit 3354 ( S1123). The processing performed by the movement distance calculation unit 3355 in this case will be specifically described.

  FIG. 13A is an example of a movement route when the mobile terminal 300 moves from the start point to the end point (current position). FIG. 13B shows from the movement distance / direction history 1300 and the movement distance / direction history 1300 recorded in the memory 312 by the movement distance / direction history recording unit 3352 when the mobile terminal 300 moves as shown in FIG. The absolute moving distance and moving direction (indicated by an angle with respect to the north) from the starting point of the mobile terminal 300 obtained are shown. In addition, the absolute movement distance from the starting point of the portable terminal 300 is calculated | required as the length of the synthetic | combination vector of the vector which connects between each time.

  Returning to FIG. 11 again, in S1124, the second free space loss calculation unit 3356 calculates the second free space loss based on the absolute movement distance from the starting point obtained by the movement distance calculation unit 3355. In S1125, the free space loss comparison unit 3357 compares the first free space loss and the second free space loss, and determines whether the position location signal being received is a direct wave or a reflected wave. Here, this determination is performed as follows. That is, when the first free space loss is smaller than the second free space loss by a predetermined value (for example, 3 dB) or more, that is, the first free space loss obtained from the received signal strength of the position location signal being received is absolute. If it is smaller than the second free space loss calculated from the moving distance by a predetermined value or more, it is determined that the position location signal being received is a reflected wave, and if not, it is determined to be a direct wave. Note that the predetermined value is set to a value that can reliably identify the direct wave and the reflected wave.

  A specific example of the determination by the free space loss comparison unit 3357 is shown. FIG. 14 is a diagram illustrating a state near the installation site of the base station 200, and illustrates a state in which a direct wave and a reflected wave due to multipath arrive from the base station 200 to the mobile terminal 300. The base station 200 is installed at a height of 5 m from the ground, and the mobile terminal 300 is located at a height of 1 m from the ground. The distance on the ground surface between the base station 200 and the mobile terminal 300 is 12 m.

  In the figure, the reflected wave is reflected at a position 10 m from directly below the base station 200 on the line connecting the base station 200 and the mobile terminal 300 and reaches the mobile terminal 300. The straight line distance from the antenna 2151 of the base station 200 to the reflection point of the reflected wave is 13.417 m. The straight line distance from the antenna 2151 of the base station 200 to the mobile terminal 300 is 12.649 m.

When the frequency of the location signal transmitted from the base station 200 is 2.4 GHz (wavelength λ = 0.125 m), the free space loss of the direct wave is calculated,
Free wave loss of direct wave = 20 log ₁₀ ((4π × 12.649) /0.125)
= 62.087 (dBm)
It becomes.

On the other hand, the free space loss of the reflected wave is
Free space loss of reflected wave = 20 log 10 ((4π × 13.417) /0.125)
= 62.599 (dBm)
It becomes. If the signal strength loss due to reflection on the ground surface is 3 dBm, the total loss of the reflected wave is
62.599 (dBm) +3 (dBm) = 65.599 (dBm)
It becomes. Therefore, in the example shown in FIG. 14, the difference between the free space loss of the direct wave and the free space loss of the reflected wave is 65.599 (dBm) −62.087 (dBm) = 3.512 (dBm)
It becomes. That is, if the predetermined value is set to about 3 (dBm), the direct wave and the reflected wave can be distinguished.

  By the way, description of the above embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, the location of the mobile terminal 300 may be performed on the mobile terminal 300 side by receiving the location signal transmitted from the base station 200 on the mobile terminal 300 side as described in the above embodiment. Then, an antenna group is provided on the mobile terminal 300 side, and a position location signal is transmitted from the mobile terminal 300 side to the base station 200. This position location signal is received on the base station 200 side, and the location on the base station 200 side is determined. You may make it perform.

It is a figure which shows schematic structure of the autonomous movement assistance system 1 demonstrated as one Embodiment of this invention. It is a figure which shows the hardware constitutions of the server apparatus 100 demonstrated as one Embodiment of this invention. It is a figure which shows the function of the server apparatus 100 demonstrated as one Embodiment of this invention. It is a figure which shows the hardware constitutions of the base station 200 demonstrated as one Embodiment of this invention. It is a figure which shows the function of the base station 200 demonstrated as one Embodiment of this invention. It is a figure which shows the hardware constitutions of the portable terminal 300 demonstrated as one Embodiment of this invention. It is a figure which shows the function of the portable terminal 300 demonstrated as one Embodiment of this invention. It is a figure which shows the detail of the function of the direct wave determination part 335 of the portable terminal 300 demonstrated as one Embodiment of this invention. It is a figure which shows the data format of the position determination signal demonstrated as one Embodiment of this invention. It is a figure which shows the positional relationship of the base station 200 demonstrated as one Embodiment of this invention and the portable terminal 300. FIG. It is a figure explaining the positional relationship of the antenna 2151 and the portable terminal 300 which comprise the antenna group 215 demonstrated as one Embodiment of this invention. It is a figure which shows the positional relationship of the base station 200 and the portable terminal 300 in the field demonstrated as one Embodiment of this invention. It is a flowchart explaining the position location process (S1000) by one Embodiment of this invention. It is a flowchart explaining the direct wave determination process (S1012) by one Embodiment of this invention. It is an example of the received signal strength log | history 1200 demonstrated as one Embodiment of this invention. It is a figure which shows an example of the movement path | route at the time of the portable terminal 300 demonstrated as one Embodiment of this invention moving from the origin to the end point (present position). It is a figure which shows an example of the movement distance / direction log | history 1300 demonstrated as one Embodiment of this invention. It is a figure which shows the mode of the installation site vicinity of the base station 200 demonstrated as one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Position determination system 200 Base station 213 Communication interface 214 Wireless communication interface 263 Position determination signal transmission part 300 Portable terminal 313 Wireless communication interface 318 Acceleration sensor 319 Geomagnetic sensor 320 RSSI circuit 331 Position determination signal reception part 334 Position determination part 335 Direct wave determination Unit 1200 received signal strength history 1300 travel distance / direction history 3351 received signal strength history recording unit 3352 travel distance / direction history recording unit 3353 first free space loss calculation unit 3354 origin setting unit 3355 travel distance calculation unit 3356 second free space loss Calculation unit 3357 Free space loss comparison unit S1000 Positioning processing S1012 Direct wave determination processing

Claims (5)

A positioning signal receiving unit that receives a positioning signal that is a radio signal for locating its current position;
A position locating unit for locating its current position based on the position locating signal;
A circuit for obtaining the received signal strength of the position location signal;
An acceleration sensor;
A geomagnetic sensor,
A received signal strength history recording unit that generates a received signal strength history in which the received signal strength history of the location signal is recorded in association with the reception time of the location signal;
Based on the detection values of the acceleration sensor and the geomagnetic sensor, a movement distance / direction history recording unit that generates a movement distance / direction history in which a movement history for each predetermined time interval is recorded in association with the acquisition time of the detection value. When,
A first free space loss calculation unit that obtains a first free space loss that is a free space loss of the received position location signal from the received signal strength of the received position location signal;
From the received signal strength history, a starting point setting unit for specifying a starting time that is the latest time from the current time when the received signal strength of the received position location signal is maximized;
Based on the starting point time and the moving distance / direction history, a moving distance calculating unit for obtaining a distance from the own position to the current position at the starting point time;
A second free space loss calculation unit that obtains a second free space loss that is a free space loss of the positioning signal based on the moving distance;
A free space loss comparison unit that compares the first free space loss with the second free space loss to determine whether the received positioning signal is a direct wave;
Have
The position locating unit prevents the position locating based on the received position locating signal when the free space loss comparing unit determines that the position locating signal is not a direct wave. Mobile terminal used for The mobile terminal according to claim 1,
The free space loss comparison unit determines that the received positioning signal is not a direct wave when a difference between the first free space loss and the second free space loss is equal to or greater than a predetermined value. A mobile terminal used for positioning. The mobile terminal according to claim 1,
The position locating unit determines its current position based on the detection values of the acceleration sensor and the geomagnetic sensor when the free space loss comparing unit determines that the position locating signal is not a direct wave. A mobile terminal used for location. The mobile terminal according to claim 1,
The position locating unit receives a plurality of the position locating signals transmitted from each of a plurality of antennas arranged adjacent to each other, and locates its current position based on a phase difference between the received position locating signals. A portable terminal used for positioning. A position location system,
Multiple base stations installed in various locations in the area,
A mobile device carried by a traveler,
Including
The base station transmits a plurality of positioning signals having different phases, which are radio signals for positioning from each of a plurality of adjacently arranged antennas,
The portable terminal is
A position location signal receiver for receiving the position location signal;
A position locating unit for locating its current position based on the position locating signal;
A circuit for obtaining the received signal strength of the position location signal;
An acceleration sensor;
A geomagnetic sensor,
A received signal strength history recording unit that generates a received signal strength history in which the received signal strength history of the location signal is recorded in association with the reception time of the location signal;
Based on the detection values of the acceleration sensor and the geomagnetic sensor, a movement distance / direction history recording unit that generates a movement distance / direction history in which a movement history for each predetermined time interval is recorded in association with the acquisition time of the detection value. When,
A first free space loss calculation unit that obtains a first free space loss that is a free space loss of the received position location signal from the received signal strength of the received position location signal;
From the received signal strength history, a starting point setting unit for specifying a starting time that is the latest time from the current time when the received signal strength of the received position location signal is maximized;
Based on the starting point time and the moving distance / direction history, a moving distance calculating unit for obtaining a distance from the own position to the current position at the starting point time;
A second free space loss calculation unit that obtains a second free space loss that is a free space loss of the positioning signal based on the moving distance;
A free space loss comparison unit that compares the first free space loss with the second free space loss to determine whether the received positioning signal is a direct wave;
Have
The position locating unit prevents the position locating based on the received position locating signal when the free space loss comparing unit determines that the position locating signal is not a direct wave. system.

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