JP2010185830A - Mobile terminal, gps positioning method, and gps positioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology allowing use of the position of a wireless base station as an initial value of the positioning of the current position, even if the positional information is not acquired from the wireless base station every position registration. <P>SOLUTION: This mobile terminal includes a position registering means for registering the position in the wireless base station when a signal transmitted from the wireless base station is received, a current position managing means for accumulating, as a base station position list, the base station position as the position of the wireless base station acquired from the wireless base station in association with the wireless base station, an initial position managing means that manages the initial position used as the initial value for calculating the current position and updates the initial position to the base station position, if the base station position of the wireless base station is recorded on the base station position list when the position is registered in a new wireless base station, and a current-position calculating means for performing operation for calculating the current position using received electric waves from a GPS (global positioning) satellite, utilitizing the initial position as the initial value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mobile terminal, a GPS positioning method, and a GPS positioning system.

  In recent years, a GPS (Global Positioning System) that measures the position of a person using an artificial satellite has been used in mobile terminals such as mobile phones, and various services using position information have been provided. .

  In GPS, a GPS receiver receives radio waves from a plurality of GPS satellites and determines the distance to each GPS satellite. The GPS receiver obtains the current position by solving simultaneous equations based on the distance to each GPS satellite using a sequential calculation method (Newton method) or the like. When this sequential calculation method is used, an initial value of the current position of the GPS receiver (hereinafter referred to as an initial position) is required. If this initial position is far from the actual current position, the current position is obtained. Takes longer time.

  The GPS receiver estimates a GPS satellite that can receive radio waves based on the initial position. If the initial position is significantly different from the actual position, the search for the estimated GPS satellite fails, and the GPS satellite is searched again because the current position is unknown. There is also a risk of this.

  Various techniques have been proposed to estimate the initial position of the GPS receiver as accurately as possible. For example, Patent Document 1 proposes a method in which position information of a radio base station that is closest to a mobile terminal that is a GPS receiver is employed as an initial position. In Patent Document 1, the mobile terminal acquires the position information of the closest radio base station, and adopts the position indicated by the acquired position information of the radio base station as its initial position.

JP 2001-133535 A

  In Patent Document 1 described above, the position information of the radio base station cannot be used as the initial position until the position information is acquired from the closest radio base station to the mobile terminal, and the radio base station is changed every time the connected radio base station is changed. It is necessary to acquire location information from the base station.

  An object of the present invention is to provide a technique that makes it possible to use the position of a radio base station as an initial value for positioning of the current position without acquiring position information from the radio base station every time position registration is performed. It is.

  In order to achieve the above object, the mobile terminal of the present invention, if a signal transmitted from a radio base station is received, location registration means for performing location registration with the radio base station, and location registration in the past Current position management means for storing the base station position, which is the position of the radio base station, acquired from the radio base station in association with the radio base station and storing it as a base station position list, and an initial stage for calculating the current position If an initial position serving as a value is managed and the position of the base station of the wireless base station is recorded in the base station position list when the position registration to the new wireless base station is performed, the initial position is Initial position management means for updating to the base station position; and current position calculation means for performing an operation for calculating the current position using a received radio wave from a GPS satellite using the initial position as an initial value.

  In order to achieve the above object, the GPS positioning method of the present invention associates the base station position, which is the position of the radio base station, acquired from the radio base station registered in the past with the radio base station. If the base station position of the radio base station is recorded in the base station position list when the position is registered in a new radio base station, the initial position is stored in the base station position list. Updates to the station position, manages the initial position as the initial value for calculating the current position, and uses the initial position as the initial value to calculate the current position using the received radio wave from the GPS satellite To perform the operation.

  In order to achieve the above object, the GPS positioning system of the present invention performs position registration with a radio base station from which a signal is received, and the position of the radio base station acquired from a radio base station that has been registered in the past. The base station position corresponding to the radio base station is stored as a base station position list, and when the position registration to a new radio base station is performed, the base station position of the radio base station is the base station If it is recorded in the position list, the initial position is updated to the base station position to manage the initial position for calculating the current position, and the initial position is used as the initial value. A mobile terminal that performs a calculation for calculating a current position using radio waves received from GPS satellites, and a radio base station that provides the base station position when requested by the mobile terminal.

  According to the present invention, the mobile terminal can use the position of the radio base station as the initial value of the positioning of the current position without acquiring the position information from the radio base station every time the position is registered.

It is a block diagram which shows the structure of the GPS positioning system of 1st Embodiment. FIG. 2 is a diagram showing a sequence of the mobile terminal 1 and the radio base station 2 when the mobile terminal 1 shown in FIG. FIG. 2 is a diagram showing a sequence of the mobile terminal 1 and the radio base station 2 when the mobile terminal 1 shown in FIG. 1 requests assist data from the radio base station 2. It is a block diagram which shows the structure of the mobile terminal of 1st Embodiment. 5 is a flowchart showing a process when the mobile terminal 1 shown in FIG. It is a system diagram which shows the structure of a mobile terminal and a base station. It is a system diagram which shows the structure of a mobile terminal and a base station. It is a flowchart which shows a process when the mobile terminal 1 shown in FIG. 4 measures a present position. It is a figure which shows the example of a positioning log | history. It is a flowchart which shows a process when the mobile terminal 1 shown in FIG. 4 displays a present position to a user. It is a figure which shows the table in which overseas service information is set. It is a block diagram which shows the structure of the mobile terminal of 3rd Embodiment.

  Next, the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the GPS positioning system according to the first embodiment.

  As shown in FIG. 1, the GPS positioning system of the first embodiment includes a mobile terminal 1, a radio base station 2, an assist server 3, and a GPS satellite 4.

  The mobile terminal 1 is a communication terminal such as a mobile phone or a PHS (Personal Handyphone System). Furthermore, the mobile terminal 1 has a GPS receiver function, and uses the function to determine the current position.

  The mobile terminal 1 receives data including time transmitted from a plurality of GPS satellites by radio waves, and determines the distance from each GPS satellite from the received data. The mobile terminal 1 obtains the current position by solving simultaneous equations based on the distance to a plurality of GPS satellites using a sequential calculation method (Newton method) or the like. When this sequential calculation method is used, the initial position of the mobile terminal 1 is required. In addition, in order to determine whether or not the initial position can be used in an operation for measuring the current position, an initial position error indicating the accuracy of the initial position with a distance is used.

  The mobile terminal 1 uses the base station position of the connected radio base station 2 as an initial position for calculation for positioning the current position. In addition, the mobile terminal 1 uses the distance that the transmission signal of the connected radio base station 2 reaches as an initial position error for determining whether or not the initial position can be used in an operation for measuring the current position. A certain base station communication distance is used.

  Since the location of the mobile terminal 1 is registered with the radio base station 2, it is assumed that the mobile terminal 1 is somewhere within the communication area of the radio base station 2. Therefore, in the present embodiment, the position of the radio base station 2 is used as an initial value when the position of the mobile terminal 1 is measured.

  The base station communication distance corresponds to the radius of the communication area of the radio base station 2. Since the mobile terminal 1 is somewhere within the communication area of the radio base station 2, the difference between the position of the radio base station 2 and the position of the mobile terminal 1 is at most the base station communication distance. Therefore, in this embodiment, this base station communication distance is used as the initial position error.

  In mobile communication, a radio base station transmits a call signal when calling a mobile terminal. The mobile terminal needs to register on the network side which radio base station the mobile terminal belongs to so that the radio base station can send out the calling signal. Note that registration of which radio base station the mobile terminal is on the network side is called location registration. The radio base station always transmits a pilot signal and a broadcast signal so that the mobile terminal can perform location registration with the radio base station to which the mobile terminal wants to connect. The broadcast signal includes a base station code, a country code, and an operator code of the radio base station. When a user moves under the control of a radio base station that is connected to the mobile terminal, or when the user starts up the mobile terminal, the mobile terminal is the highest Location registration is performed with the radio base station from which the pilot signal is received at the reception level. As a result, the mobile terminal can perform location registration in a radio base station that enables good communication.

  The mobile terminal 1 receives a notification signal that is always distributed by the radio base station 2.

  A position in which the mobile terminal 1 includes a terminal code unique to the mobile terminal when the mobile terminal 1 moves under the control of a radio base station different from the currently connected radio base station or when the power supply is activated. Send registration request and register location.

  Information acquired for the connected radio base station 2 is recorded as base station information in a predetermined area of the database in the mobile terminal 1 (hereinafter referred to as a base station information storage area). The base station information includes base station code information and base station position information. The base station code information includes the country code, operator code, and base station code of the radio base station to which the mobile terminal is connected. The base station position information includes the base station position and base station communication distance of the radio base station to which the mobile terminal is connected.

  In the mobile terminal 1, the base station position and base station communication distance of the registered radio base station are recorded in a predetermined area (hereinafter referred to as a positioning history storage area) of a database in the mobile terminal 1. Search from positioning history.

  An example of the positioning history is shown in FIG. As shown in FIG. 9, the positioning history includes terminal information obtained by positioning, positioning method used for positioning, and base station information of a radio base station connected at the time of positioning. Each time the mobile terminal 1 measures the current position, terminal information, a positioning method, and base station information are additionally written in the positioning history storage area as a positioning history. The terminal information is recorded in a predetermined area (hereinafter referred to as a terminal information storage area) of a database in the mobile terminal 1 at the timing when the mobile terminal 1 measures the current position. The terminal information includes the terminal position that is the position of the mobile terminal 1 obtained by positioning, and the terminal position accuracy that indicates the accuracy of the terminal position by distance. The positioning method includes a single positioning method and a server assist method.

  When the base station position information of the registered radio base station exists in the positioning history, the mobile terminal 1 combines the base station position information and the base station code information in the base station information storage area as base station information. Record.

  The mobile terminal 1 manages the initial position information including the initial position, the initial position error, and the selected base station code that is the base station code of the radio base station whose base station position is selected as the initial position. . The initial position information is recorded in a predetermined area of the database in the mobile terminal 1 (hereinafter referred to as an initial position information storage area).

  When the base station position information of the registered radio base station exists in the positioning history, the mobile terminal 1 includes the base station position and base station communication distance included in the base station position information and the base station code information included in the base station code information. The station code is recorded in the initial position information storage area as the initial position of the initial position information, the initial position error, and the selected base station code. Note that the mobile terminal 1 uses the recorded initial position in a calculation for positioning the current position.

  On the other hand, when the base station position information of the registered radio base station does not exist in the positioning history, the mobile terminal 1 records base station information in which the base station position information is not set in the base station information storage area. Note that the base station code information of the base station information written at this time is the base station code information received from the radio base station.

  At this time, the mobile terminal 1 determines whether or not the initial position information in the initial position information storage area has already been recorded. If the initial position information is already recorded, the mobile terminal 1 does not update the initial position already recorded as the initial position information. Thereby, in the mobile terminal 1, the initial position already recorded as the initial position information is continuously used in the calculation for positioning the current position. In this case, it is considered that the user has moved to a radio base station other than the currently connected radio base station with the mobile terminal 1. Therefore, it is highly likely that the mobile terminal 1 has moved outside the range of the base station communication distance of the radio base station whose base station position is selected as the initial position, and the initial position already recorded as the initial position information Is considered to be less accurate. Therefore, the mobile terminal 1 corrects the initial position error recorded as the initial position information, using the base station communication distance of the destination wireless base station that has moved.

  Moreover, the mobile terminal 1 keeps not recording the initial position and the initial position error when the initial position information is not yet recorded. In this case, the mobile terminal 1 obtains the current position without using the initial position in the calculation for positioning the current position.

  When the initial position information is recorded and the initial position error is equal to or less than a predetermined threshold value set in advance, the mobile terminal 1 determines that the initial position can be used in an operation for positioning the current position, The current position is measured using the initial position.

  On the other hand, when the initial position information is not recorded, or when the initial position error of the initial position information is not equal to or less than a predetermined threshold value, the mobile terminal 1 determines the base station position from the currently connected radio base station. And the base station communication distance is acquired.

  The mobile terminal 1 uses assist data, which is a set of parameters widely used for positioning by GPS, in order to obtain the base station position and base station communication distance from the currently connected radio base station. Request. The assist data includes the base station position of the radio base station and the base station communication distance. In order to request the assist data from the radio base station 2, the mobile terminal 1 transmits an assist data request indicating that the assist data is requested.

  When the mobile terminal 1 receives assist data as a response to the assist data request from the wireless base station 2 that has transmitted the assist data request, the mobile terminal 1 extracts the base station position and the base station communication distance from the received assist data.

  The mobile terminal 1 records the extracted base station position and base station communication distance in the base station information storage area as the base station position and base station communication distance of the base station position information of the base station information, respectively. In addition, the mobile terminal 1 sets the extracted base station position and base station communication distance, and the base station code of the radio base station that has received the assist data to the initial position information, the initial position error, and the selected base station code, respectively. Is recorded in the initial position information storage area.

  The mobile terminal 1 measures the current position using the initial position recorded as the initial position information in the initial position information storage area.

  On the other hand, the mobile terminal 1 does not receive the assist data from the radio base station that has transmitted the assist data request even after a predetermined time has elapsed, so that the base station position of the connected radio base station is If it is not obtained, the current position is measured without using the initial position.

  When the positioning of the current position is completed, the mobile terminal 1 records the terminal position and the terminal position accuracy obtained by the positioning as terminal information in the terminal information storage area.

  Furthermore, the mobile terminal 1 additionally writes terminal information, a positioning method, and base station information as a positioning history in the positioning history storage area.

  Further, when the mobile terminal 1 is requested to display the current position by the user, the mobile terminal 1 determines whether or not the terminal information is recorded in the terminal information storage area. When terminal information is recorded in the terminal information storage area, the mobile terminal 1 displays the terminal position and error accuracy of the terminal information as the current position and its accuracy.

  On the other hand, when the terminal information is not recorded in the terminal information storage area, the mobile terminal 1 reads the initial position information from the initial position information storage area. The mobile terminal 1 displays the initial position and initial position error of the read initial position information as the current position and its accuracy.

  The radio base station 2 is a base station that directly communicates with the mobile terminal 1.

  The radio base station 2 always transmits a pilot signal and a broadcast signal so that the mobile terminal 1 can register a location with the radio base station to which the mobile terminal 1 wants to connect.

  Upon receiving the location registration request from the mobile terminal 1, the radio base station 2 extracts a terminal code unique to the mobile terminal from the received location registration request and registers the terminal code in a location registration database of a communication carrier (not shown) To do.

  In addition, when the assist server 3 distributes assist data, the radio base station 2 receives the assist data. When receiving the assist data request from the mobile terminal 1, the radio base station 2 transmits the assist data received from the assist server 3 to the mobile terminal 1 as a response to the assist data request.

  The assist server 3 is a server that generates assist data including a base station position of a subordinate radio base station and a base station communication distance. When the assist server 3 generates assist data, the assist server 3 distributes the generated assist data to the radio base station 2.

  The GPS satellite 4 is a satellite used in GPS. The GPS satellite 4 transmits radio waves that are used by the GPS receiver to measure the current position.

  Next, a sequence between the mobile terminal 1 and the radio base station 2 when the mobile terminal 1 shown in FIG.

  FIG. 2 is a diagram showing a sequence of the mobile terminal 1 and the radio base station 2 when the mobile terminal 1 shown in FIG.

  The radio base station 2 always transmits a pilot signal and a notification signal (step S1).

  The mobile terminal 1 receives a notification signal distributed by the radio base station 2. The mobile terminal 1 receives a pilot signal at the highest reception level when moving to a radio base station that is different from the connected radio base station or when the power source is activated (step S2). A location registration request including a terminal code unique to the mobile terminal is transmitted to the radio base station 2 (step S3).

  Upon receiving the location registration request from the mobile terminal 1, the radio base station 2 extracts a terminal code unique to the mobile terminal from the received location registration request and registers the terminal code in a location registration database of a communication carrier (not shown) (Step S4).

  Thereby, when there is a connection request from an external terminal to the mobile terminal 1, the radio base station 2 can call the mobile terminal 1.

  Next, a sequence of the mobile terminal 1 and the radio base station 2 when the mobile terminal 1 shown in FIG. 1 requests assist data from the radio base station 2 will be described.

  FIG. 3 is a diagram showing a sequence of the mobile terminal 1 and the radio base station 2 when the mobile terminal 1 shown in FIG. 1 requests the assist data from the radio base station 2.

  When the mobile terminal 1 measures the current position, it first determines whether or not base station position information that can be used in the calculation for positioning the current position exists in the positioning history in the positioning history storage area (step S11). .

  When the base station position information that can be used in the calculation for positioning the current position exists in the positioning history, the mobile terminal 1 sets the base station position and the base station communication distance of the base station position information as the initial position and the initial position, respectively. Use as an error to measure the current position.

  On the other hand, when there is no base station position information that can be used in the calculation for positioning the current position in the positioning history, the mobile terminal 1 acquires the base station position and the base station communication distance from the currently connected radio base station 2 In order to do so, an assist data request is transmitted to the radio base station 2 (step S12).

  When receiving the assist data request from the mobile terminal 1, the radio base station 2 transmits the assist data received from the assist server 3 in advance to the mobile terminal 1 as a response to the assist data request (step S13).

  When the mobile terminal 1 receives assist data as a response to the assist data request from the radio base station 2, the mobile terminal 1 extracts the base station position and the base station communication distance from the received assist data. The mobile terminal 1 measures the current position using the extracted base station position and base station communication distance as the initial position and initial position error, respectively (step S14).

  FIG. 4 is a block diagram showing the configuration of the mobile terminal according to the first embodiment.

  As shown in FIG. 4, the mobile terminal according to the first embodiment includes a current position calculation unit 11, a radio unit 12, a position registration unit 13, an initial position management unit 14, a current position management unit 15, and a current position display unit. 16 and database 17.

  The wireless unit 12 is a wireless unit that transmits and receives wireless data to and from an external wireless base station.

  The radio unit 12 receives a pilot signal and a broadcast signal that are constantly transmitted by the radio base station 2, and receives the reception level of the pilot signal and the base station code, country code, and business of the radio base station included in the received broadcast signal The person code is transmitted to the position registration unit 13. Further, when receiving the location registration request from the location registration unit 13, the radio unit 12 transmits the received location registration request to the radio base station 2.

  In addition, when the wireless unit 12 receives the assist data request from the initial position management unit 14, the wireless unit 12 transmits the received assist data request to the wireless base station 2. In addition, when the wireless unit 12 receives assist data from the wireless base station 2 as a response to the assist data request, the wireless unit 12 transmits the received assist data to the initial position management unit 14.

  The location registration unit 13 controls radio communication of the mobile terminal such as connection with a radio base station and handover.

  The location registration unit 13 receives the reception level of the pilot signal of the radio base station 2, the base station code, the country code, and the operator code from the radio unit 12.

  When the mobile terminal 1 moves under a radio base station different from the connected radio base station, or when the power of the mobile terminal 1 is activated, the location registration unit 13 Then, a location registration request is transmitted to the radio base station that has received the pilot signal at the highest reception level, and the location registration is performed to the radio base station.

  When the location registration unit 13 registers the location in the radio base station 2, the country code, the operator code, and the base station code received from the registered radio base station 2 are stored in the initial location management unit 14 as base station code information. Send. Note that the base station code information includes a base station code, a country code, and an operator code of the radio base station to which the mobile terminal is connected.

  When receiving the base station code information from the location registration unit 13, the initial location management unit 14 transmits a base station location information request indicating that the current location management unit 15 requests base station location information. The base station location information request includes base station code information of the radio base station to which the mobile terminal 1 is currently connected.

  When receiving the base station position information as a response to the base station position information request from the current position management unit 15, the initial position management unit 14 extracts the base station position and the base station communication distance from the received base station position information. The initial position management unit 14 uses the extracted base station position and base station communication distance, and the base station code of the base station code information received from the position registration unit 13 as the initial position information, initial position error, and selected base station code. Is recorded in the initial position information storage area of the database 17. Note that the recorded initial position is used by the current position calculation unit 11 for calculation to determine the current position of the mobile terminal 1.

  On the other hand, when the initial position management unit 14 receives from the current position management unit 15 that the base station position information of the radio base station does not exist as a response to the base station position information request, the initial position information is stored in the initial position information storage area. It is determined whether or not it has already been recorded. If the initial position information is already recorded, the initial position management unit 14 does not update the initial position already recorded as the initial position information. Thereby, in the current position management unit 15, the initial position already recorded as the initial position information is continuously used in the calculation for positioning the current position.

  In this case, it is considered that the user has moved to a wireless base station other than the currently connected wireless base station with the mobile terminal 1. Therefore, it is highly likely that the mobile terminal 1 has moved outside the range of the base station communication distance of the radio base station whose base station position is selected as the initial position, and the initial position already set as the initial position information Is considered to be less accurate. Therefore, the initial position management unit 14 corrects the initial position error recorded as the initial position information, using the base station communication distance of the destination wireless base station that has moved.

  Further, the initial position management unit 14 keeps not recording the initial position and the initial position error when the initial position information is not yet recorded. In this case, the current position calculation unit 11 obtains the current position without using the initial position in the calculation for positioning the current position.

  When the initial position information is requested from the current position calculator 11, the initial position manager 14 determines whether or not the initial position information is recorded in the initial position information storage area. When the initial position information is recorded in the initial position information storage area and the initial position error is equal to or less than a predetermined threshold value, the initial position management unit 14 performs an initial position calculation by calculating the current position. The initial position information is transmitted to the current position calculation unit 11.

  On the other hand, the initial position management unit 14 is currently connected when the initial position information is not recorded in the initial position information storage area or when the initial position error of the initial position information is not less than a predetermined threshold value set in advance. A base station position and a base station communication distance are acquired from a radio base station.

  The initial position management unit 14 requests assist data from the radio base station in order to obtain the base station position and the base station communication distance from the currently connected radio base station. The initial location management unit 14 reads the base station code from the base station code information received from the location registration unit 13 and transmits an assist data request to the radio base station of the base station code via the radio unit 12.

  When receiving the assist data from the radio base station that transmitted the assist data request via the radio unit 12, the initial position management unit 14 extracts the base station position and the base station communication distance from the received assist data.

  The initial position management unit 14 obtains base station information, which is a combination of base station position information including the extracted base station position and base station communication distance, and base station code information received from the position registration unit 13, It transmits to the part 15.

  Further, the initial position management unit 14 extracts the initial position of the initial position information stored in the initial position information storage area, the initial position error, the base station communication distance extracted from the selected base station code, and the current connection. Update to the base station code of the existing radio base station.

  The initial position management unit 14 transmits the initial position of the updated initial position information to the current position calculation unit 11.

  On the other hand, the initial position management unit 14 could not obtain the base station position of the connected radio base station because the assist data was not received from the radio base station even after a predetermined time had elapsed. In this case, the current position calculation unit 11 is notified that there is no initial position information.

  Further, when the initial position information is requested from the current position display unit 16, the initial position management unit 14 reads the initial position information from the initial position information storage area. The initial position management unit 14 transmits initial position information to the current position display unit 16.

  When receiving the base station position information request from the initial position management unit 14, the current position management unit 15 extracts base station code information from the received base station position information request. The current position management unit 15 searches the base station position information of the radio base station of the extracted base station code information from the positioning history recorded in the positioning history storage area of the database 17.

  Note that the positioning history includes terminal information, positioning method, and base station information. Each time the current position is measured, terminal information, positioning method, and base station information are additionally written in the positioning history storage area as positioning history. The base station information is recorded in the base station information storage area of the database 17. The base station information includes base station code information and base station position information. The base station position information includes the base station position and base station communication distance of the radio base station to which the mobile terminal is connected. The terminal information is recorded in the terminal information storage area of the database 17. The terminal information includes the terminal position that is the position of the mobile terminal 1 obtained by positioning, and the terminal position accuracy that indicates the accuracy of the terminal position by distance.

  When the base station position information of the radio base station of the extracted base station code exists in the positioning history, the current position management unit 15 sends the base station position information to the initial position management unit 14 as a response to the base station position information request. Send. In addition, the current position management unit 15 combines the base station position information transmitted to the initial position management unit 14 with the base station code information included in the base station position information request received from the initial position management unit 14. Is recorded in the base station information storage area.

  On the other hand, if the base station position information of the radio base station of the extracted base station code does not exist in the positioning history, the current position management unit 15 requests that the base station position information of the radio base station does not exist. As a response to the initial position management unit 14. At this time, the current location management unit 15 records the base station information in which the base station location information is not set in the base station information storage area. Note that the base station code information of the base station information recorded at this time is the base station code information included in the base station position information request received from the initial position management unit 14.

  Further, when receiving the base station information from the initial position management unit 14, the current position management unit 15 records the received base station information in the base station information storage area.

  In addition, when receiving the terminal information from the current position calculation unit 11 that measures the current position, the current position management unit 15 records the received terminal information in the terminal information storage area.

  Further, the current position management unit 15 additionally writes terminal information, a positioning method, and base station information as a positioning history in the positioning history storage area.

  In addition, when the current position management unit 15 requests the terminal information from the current position display unit 16, the current position management unit 15 reads the terminal information from the terminal information storage area. The current position management unit 15 transmits the terminal information to the current position display unit 16 when the terminal information is recorded in the terminal information storage area.

  On the other hand, when no terminal information is recorded in the terminal information storage area, the current position management unit 15 transmits to the current position display unit 16 that no terminal information exists.

  The current position calculation unit 11 receives data including time transmitted from a plurality of GPS satellites by radio waves, and calculates the distance from each GPS satellite from the received data. The current position calculation unit 11 obtains the current position by solving simultaneous equations based on the distance to a plurality of GPS satellites using a sequential calculation method (Newton method) or the like. When this sequential calculation method is used, the initial position of the mobile terminal 1 is required. In addition, in order to determine whether or not the initial position can be used in the calculation for positioning the current position, an initial position error indicating the accuracy of the initial position with a distance is used.

  The current position calculation unit 11 requests initial position information from the initial position management unit 14 when determining the current position.

  When the current position calculation unit 11 acquires the initial position information from the initial position management unit 14, the current position calculation unit 11 measures the current position using the acquired initial position information.

  On the other hand, when notified from the initial position management unit 14 that the initial position does not exist, the current position calculation unit 11 measures the current position without using the initial position information.

  When the positioning of the current position is completed, the current position calculation unit 11 notifies the current position management unit 15 of the terminal position and the terminal position accuracy obtained by the positioning as terminal information.

  When the display of the current position is requested by the user, the current position display unit 16 requests terminal information from the current position management unit 15.

  When receiving the terminal information from the current position management unit 15, the current position display unit 16 extracts the terminal position and the error accuracy from the received terminal information. The current position display unit 16 displays the extracted terminal position and error accuracy as the current position and its accuracy.

  On the other hand, upon receiving from the current position management unit 15 that the terminal information does not exist, the current position display unit 16 requests the initial position information from the initial position management unit 14.

  When receiving the initial position information from the initial position management unit 14, the current position display unit 16 extracts the initial position and the initial position error from the received initial position information. The current position display unit 16 displays the extracted initial position and initial position error as the current position and its accuracy.

  The database 17 is a database that stores base station information, terminal information, initial position information, and positioning history.

  Next, processing when the mobile terminal 1 shown in FIG. 4 performs location registration in the radio base station 2 will be described.

  FIG. 5 is a flowchart showing processing when the mobile terminal 1 shown in FIG.

  The location registration unit 13 receives the reception level of the pilot signal of the radio base station 2, the base station code, the country code, and the operator code via the radio unit 12.

  When the mobile terminal 1 moves under the control of a different radio base station from the connected radio base station or when the power of the mobile terminal 1 is activated, the location registration unit 13 Then, a location registration request is transmitted to the radio base station from which the pilot signal is received at the highest reception level, and the location registration is performed to the radio base station (step S21).

  When the location registration unit 13 registers the location with the radio base station 2, the location registration unit 13 registers the location with the radio base station 2. When the location registration unit 13 registers the location with the radio base station 2, the country code, the operator code, and the base code received from the location registered radio base station 2 are displayed. The station code is transmitted to the initial position management unit 14 as base station code information.

  When receiving the base station code information from the location registration unit 13, the initial location management unit 14 transmits a base station location information request indicating that the base location information is requested to the current location management unit 15 (step S22).

  When receiving the base station position information request from the initial position management unit 14, the current position management unit 15 extracts base station code information from the received base station position information request. The current position management unit 15 searches the base station position information of the radio base station of the extracted base station code information from the positioning history recorded in the positioning history storage area.

  The current position management unit 15 first searches the positioning history for base station code information extracted from the received base station position information request. If there is matching base station code information in the positioning history, the current position management unit 15 determines whether or not base station position information is recorded corresponding to the base station code information.

  When the target base station position information exists in the positioning history, the current position management unit 15 transmits the base station position information to the initial position management unit 14 as a response to the base station position information request (step S23). In addition, the current position management unit 15 displays base station information that is a combination of the base station position information and the base station code information included in the base station position information request received from the initial position management unit 14 in the base station information storage area. To record.

  On the other hand, when the target base station position information does not exist in the positioning history, the current position management unit 15 transmits to the initial position management unit 14 as a response to the base station position information request that there is no base station position information. . At this time, the current location management unit 15 records the base station information in which the base station location information is not set in the base station information storage area. Note that the base station code information of the base station information recorded at this time is the base station code information included in the base station position information request received from the initial position management unit 14.

  When receiving the response of the base station position information request from the current position management unit 15, the initial position management unit 14 determines whether the base station position information has been acquired (step S24).

  When receiving the base station position information as a response to the base station position information request from the current position management unit 15, the initial position management unit 14 extracts the base station position and the base station communication distance from the received base station position information. The initial position management unit 14 uses the extracted base station position, base station communication distance, and base station code of the base station code information received from the position registration unit 13 as the initial position information, initial position error, and selected base information. The station code is recorded in the initial position information storage area (step S25). Note that the recorded initial position is used by the current position calculation unit 11 for calculation to determine the current position of the mobile terminal.

  On the other hand, if the initial position management unit 14 receives from the current position management unit 15 that the base station position information does not exist as a response to the base station position information request, has the initial position information already recorded in the initial position information storage area? It is determined whether or not (step S26).

  If the initial position information is not yet recorded, the initial position management unit 14 keeps the initial position and the initial position error unrecorded, and ends the process. In this case, the current position calculation unit 11 obtains the current position without using the initial position in the calculation for positioning the current position.

  On the other hand, when the initial position information is already recorded, the initial position management unit 14 does not update the initial position already recorded as the initial position information. Thereby, in the current position management unit 15, the initial position already recorded as the initial position information is continuously used in the calculation for positioning the current position.

  In this case, it is considered that the user has moved to a wireless base station other than the currently connected wireless base station with the mobile terminal 1. Therefore, it is highly likely that the mobile terminal 1 has moved outside the range of the base station communication distance of the radio base station whose base station position is selected as the initial position, and the initial position already set as the initial position information Is considered to be less accurate. Therefore, the initial position management unit 14 corrects the initial position error recorded as the initial position information by using the base station communication distance of the destination wireless base station that has moved (step S27).

  For example, as shown in FIG. 6, when a mobile terminal moves from a base station A to a base station B, the mobile terminal can be moved from the base station A as long as the mobile terminal is under the base station B. The base station A is estimated to be within a distance obtained by adding a distance twice the base station communication distance of the base station B to the base station communication distance of the base station A. Therefore, a value obtained by adding a distance twice the base station communication distance of the moved base station to the initial position error set as the initial position information is updated as a new initial position error. In the example of FIG. 6, 2bkm, which is twice the base station communication distance of the base station B, is added to the base station communication distance akm of the base station A, which is an initial position error before movement (a + 2b) km is updated. Initial position error.

  Note that the base station communication distance varies depending on the radio communication method and the radio frequency band. By setting the base station communication distance for each radio communication method and radio frequency band in advance, the initial position management unit 14 can acquire the base station communication distance of the radio base station to which the mobile terminal has moved. If the base station communication distance of the destination radio base station is unknown, it is assumed that the communication distance for each base station is almost the same, and the base of the radio base station whose base station position is set as the initial position A value obtained by adding a distance twice the station communication distance to the current initial position error may be updated as a new initial position error.

  In addition, when the mobile terminal further moves and changes the radio base station to be registered before acquiring the base station position and base station communication distance of the destination radio base station, the initial position management unit 14 Further, the initial position error is updated. At this time, the initial position management unit 14 adds the initial position error before the movement to the initial position information using a value obtained by adding a distance twice the base station communication distance of the destination radio base station as a new initial position error. Update. Each time the radio base station to be registered is changed, the initial position error is updated by adding a distance twice the communicable distance of the destination base station to the initial position error.

  Next, processing when the mobile terminal 1 shown in FIG. 4 measures the current position will be described.

  FIG. 8 is a flowchart showing processing when the mobile terminal 1 shown in FIG. 4 measures the current position.

  The current position calculation unit 11 receives data including time transmitted from a plurality of GPS satellites by radio waves, and calculates the distance from each GPS satellite from the received data. The current position calculation unit 11 obtains the current position by solving simultaneous equations based on the distance to a plurality of GPS satellites using a sequential calculation method (Newton method) or the like. When this sequential calculation method is used, the initial position of the mobile terminal 1 is required. In addition, in order to determine whether or not the initial position can be used in an operation for measuring the current position, an initial position error indicating the accuracy of the initial position with a distance is used.

  When obtaining the current position, the current position calculation unit 11 first requests initial position information from the initial position management unit 14 (step S31).

  When the initial position information is requested from the current position calculation unit, the initial position management unit 14 determines whether or not the initial position information is recorded in the initial position information storage area (step S32).

  When the initial position information is recorded in the initial position information storage area, the initial position management unit 14 determines whether or not the initial position error of the initial position information is equal to or less than a predetermined threshold value set in advance (step). S33). When the initial position error is equal to or less than a predetermined threshold value set in advance, the initial position management unit 14 determines that the initial position can be used in an operation for measuring the current position, and sends the initial position information to the current position calculation unit 11. Transmit (step S37).

  When acquiring the initial position from the initial position management unit 14, the current position calculation unit 11 measures the current position using the acquired initial position (step S38).

  On the other hand, the initial position management unit 14 is currently connected when the initial position information is not recorded in the initial position information storage area or when the initial position error of the initial position information is not less than a predetermined threshold value set in advance. A base station position and a base station communication distance are acquired from the radio base station (step S34).

  The initial position management unit 14 requests assist data from the radio base station in order to obtain the base station position and the base station communication distance from the currently connected radio base station. The initial location management unit 14 reads the base station code from the base station code information received from the location registration unit 13 and transmits an assist data request to the radio base station of the base station code via the radio unit 12.

  When transmitting the assist data request, the initial position management unit 14 determines whether or not the assist data has been received as a response to the assist data request from the wireless base station that transmitted the assist data request (step S35).

  When receiving the assist data from the radio base station that transmitted the assist data request via the radio unit 12, the initial position management unit 14 extracts the base station position and the base station communication distance from the received assist data.

  The initial position management unit 14 obtains base station information, which is a combination of base station position information including the extracted base station position and base station communication distance, and base station code information received from the position registration unit 13, It transmits to the part 15 (step S36).

  When receiving the base station information from the initial position management unit 14, the current position management unit 15 records the received base station information in the base station information storage area.

  Further, the initial position management unit 14 connects the extracted initial position, initial position error, and selected base station code of the initial position information stored in the initial position information storage area, the base station position, the base station communication distance, and the current connection. Update to the base station code of the current radio base station.

  Further, the initial position management unit 14 transmits the updated initial position information to the current position calculation unit 11 (step S37).

  When acquiring the initial position from the initial position management unit 14, the current position calculation unit 11 measures the current position using the acquired initial position (step S38).

  On the other hand, the initial position management unit 14 could not obtain the base station position of the connected radio base station because the assist data was not received from the radio base station even after a predetermined time had elapsed. In this case, the current position calculation unit 11 is notified that the initial position does not exist (step S39).

  When the current position calculation unit 11 is notified from the initial position management unit 14 that the initial position does not exist, the current position calculation unit 11 measures the current position without using the initial position (step S40).

  When the positioning of the current position is completed, the current position calculation unit 11 notifies the current position management unit 15 of the terminal position and the terminal position accuracy obtained by the positioning as terminal information (step S41).

  When receiving the terminal information from the current position calculation unit 11, the current position management unit 15 records the received terminal information in the terminal information storage area.

  Furthermore, the current position management unit 15 additionally writes terminal information, a positioning method, and base station information as a positioning history in the positioning history storage area (step S42).

  Next, processing when the user terminal 1 shown in FIG. 4 displays the current position to the user will be described.

  FIG. 10 is a flowchart showing processing when the user terminal 1 shown in FIG. 4 displays the current position to the user.

  When the display of the current position is requested by the user, the current position display unit 16 requests terminal information from the current position management unit 15 (step S51).

  When the current position management unit 15 requests terminal information from the current position display unit 16, the current position management unit 15 determines whether the terminal information is recorded in the terminal information storage area. When the terminal information is recorded in the terminal information storage area, the current position management unit 15 transmits the terminal information to the current position display unit 16 (step S52). On the other hand, when the terminal information is not recorded in the terminal information storage area, the current position management unit 15 transmits that the terminal information is not recorded in the current position display unit 16.

  The current position display unit 16 determines whether terminal information has been received from the current position management unit 15 (step S53).

  When receiving the terminal information from the current position management unit 15, the current position display unit 16 extracts the terminal position and the error accuracy from the received terminal information. The current position display unit 16 displays the extracted terminal position and error accuracy as the current position and its accuracy (step S54).

  On the other hand, when terminal information is not recorded in the terminal information storage area, it is considered that the user terminal 1 has not yet measured the current position. For this reason, the current position display unit 16 displays the initial position and initial position error of the base station information as an alternative to the current position.

  When the current position display unit 16 receives that the terminal information is not recorded from the current position management unit 15, the current position display unit 16 requests the initial position information from the initial position management unit 14 (step S55).

  When the initial position information is requested from the current position display unit 16, the initial position management unit 14 reads the initial position information from the initial position information storage area. The initial position management unit 14 transmits initial position information to the current position display unit 16 (step S56).

  When receiving the initial position information from the initial position management unit 14, the current position display unit 16 extracts the initial position and the initial position error from the received initial position information. The current position display unit 16 displays the extracted initial position and initial position error as the current position and its accuracy (step S57).

  In the first embodiment, the initial position management unit 14 must have the recorded initial position information valid at the timing when the initial position information is requested to obtain the current position from the current position calculation unit 11. For example, the assist data was acquired from the radio base station and the initial position information was updated. The timing for updating the initial position information may be immediately after the position registration unit 13 registers the position.

  In the first embodiment, the initial position management unit 14 acquires base station position information of base station information from the positioning history recorded in the positioning history storage area. The base station position information may be managed by a base station position list indicating the base station position information and the base station code information for each radio base station.

  The base station position list is created by the current position management unit 15 in a predetermined area of the database 17 (hereinafter referred to as a base station position list storage area). The current position management unit 15 updates the base station position list in the base station position list storage area with the base station position information transmitted by the initial position management unit 14 in step S36. In addition, when receiving the base station position information request transmitted by the initial position management unit 14 in step S22, the current position management unit 15 displays the base station position information of the radio base station requested for the base station position information in the base station position list. Search from the base station location list recorded in the storage area.

  The assist data received from the radio base station 2 may include the base station position and base station communication distance of the radio base station adjacent to the radio base station 2 in some cases. In this case, the initial location management unit 14 transmits the base station information to the current location management unit 15 including the base station information of the adjacent radio base station in step S36. The current position management unit 15 updates the base station position list in the base station position list storage area with the received base station information including the base station information of the adjacent radio base station.

  This improves the possibility that the initial position management unit 14 can acquire the base station position information of the radio base station to which the user terminal 1 has moved when the user base 1 changes the radio base station whose position is registered. To do.

  FIG. 7 shows an example in which the mobile terminal moves from the base station A to the base station B and then to the base station C. At this time, if the assist data is not received while being under the control of the base station B, the initial position remains the base station position of the base station A, and the initial position error is (a + 2b + 2c) km.

  On the other hand, when the current position management unit 15 receives the assist data of the base station A, if the base station position information of the adjacent base station C is stored in the base station position list of the base station position list storage area, The initial position can be the base station position of the base station C, and the initial position error can be ckm.

  As described above, according to the present embodiment, if the position of the radio base station with which the mobile terminal has been registered is recorded in the past, that position becomes the initial position. The position of the radio base station can be used as an initial value for positioning of the current position without acquiring position information from the radio base station each time registration is performed.

  In addition, since the mobile terminal determines whether or not the initial position can be used for positioning of the current position based on the initial position error, only the initial position that is not far away from the actual current position is used as the initial value of the positioning of the current position. Can be used.

  In addition, when a mobile terminal registers a position in a new radio base station, the initial position error is corrected using the base station communication distance of the radio base station, so whether or not the initial position can be used for positioning of the current position. Can be accurately determined.

  In addition, since the mobile terminal displays the initial position as the current position until the current position is measured, the approximate current position can be displayed to the user even when the current position cannot be measured.

(Second Embodiment)
The second embodiment is an example in which the mobile terminal according to the first embodiment is used overseas by international roaming.

  The basic configuration of the mobile terminal 1 of the present embodiment is the same as that of the mobile terminal 1 of the first embodiment. The mobile terminal 1 of the present embodiment has the functions provided by the mobile terminal 1 of the first embodiment. When the mobile terminal 1 is connected to a radio base station of a contracted telecommunications carrier, the first The same operation as that of the embodiment is performed. And the mobile terminal 1 of this embodiment is provided with the following structures and functions in addition to it. The following configurations and functions are used when connected to overseas radio base stations by international roaming.

  In addition to the information stored in the first embodiment, overseas service information shown in FIG. 11 is set in advance in a predetermined area of the database 17 of the mobile terminal 1 of the present embodiment. As shown in FIG. 11, in the overseas service information, a country identification code, a provider code, a service initial position, and a service range are set in advance for each service provider that provides an international roaming service.

  In the present embodiment, when the mobile terminal 1 is connected to a radio base station in another country by international roaming, the mobile terminal 1 uses not a position of the radio base station but a predetermined point in the country (hereinafter referred to as “service initial position”). The initial position. Further, when the mobile terminal 1 sets the service initial position, the mobile terminal 1 sets an initial position error with respect to the service initial position. For example, the distance from the initial position to the farthest position in the area (hereinafter referred to as “service range”) in which the telecommunications carrier of the connected wireless base station provides the communication service is set as the initial position error. May be.

  When registering the position with the wireless base station of the contracted communication carrier, the position management unit 13 performs the same operation as that of the first embodiment.

  When the location registration unit 13 registers a location with an overseas radio base station by international roaming, the location registration unit 13 extracts a country code and an operator code from the notification signal received from the registered radio base station. The location registration unit 13 transmits the extracted country code and business operator code to the initial location management unit 14 as base station code information.

  When the initial location management unit 14 receives the base station code information from the location registration unit 13, the initial location management unit 14 extracts the country code and the operator code from the received notification signal. The initial location management unit 14 acquires the initial service location and service range corresponding to the extracted country code and business operator code from the overseas service information recorded in a predetermined area of the database 17.

  The initial position management unit 14 records the acquired service initial position as the initial position of the initial position information and the service range as the initial position error of the initial position information in the initial position information storage area.

  When obtaining the current position, the current position calculation unit 11 first requests the initial position information from the initial position management unit 14.

  When the initial position information is requested from the current position calculation unit 11, the initial position management unit 14 determines whether or not the initial position error of the initial position information is equal to or less than a predetermined threshold value set in advance.

  When the initial position error is equal to or less than a predetermined threshold value set in advance, it is determined that the initial position can be used in the calculation for positioning the current position, and the initial position is transmitted to the current position calculation unit 11.

  When acquiring the initial position from the initial position management unit 14, the current position calculation unit 11 measures the current position using the acquired initial position.

  On the other hand, when the initial position error is equal to or less than a predetermined threshold value set in advance, the initial position management unit 14 notifies the current position calculation unit 11 that there is no initial position.

  When notified from the initial position management unit 14 that the initial position does not exist, the current position calculation unit 11 measures the current position without using the initial position.

  When the positioning of the current position is completed, the current position calculation unit 11 notifies the current position management unit 15 of the terminal position and the terminal position accuracy obtained by the positioning as terminal information.

  When receiving the terminal information from the current position calculation unit 11, the current position management unit 15 records the received terminal information in the terminal information storage area.

  Furthermore, the current position management unit 15 additionally writes the terminal information and the positioning method in the positioning history storage area as the positioning history.

  When the display of the current position is requested by the user, the current position display unit 16, the current position management unit 15, and the initial position management unit 15 perform the same operations as those in the first embodiment.

  As a result, the mobile terminal 1 can determine a predetermined point in the country only when the area where the communication provider of the connected radio base station provides the communication service is equal to or less than a predetermined threshold value set in advance. Can be used as an initial value for positioning of the current position. Furthermore, the mobile terminal 1 does not change a predetermined point in the country until the current position is determined, regardless of the area of the area where the communication provider of the connected wireless base station provides the communication service. Can be displayed as a position.

  As described above, according to the present embodiment, when a location is registered with a radio base station in a predetermined country by international roaming, a predetermined specific location in a predetermined country can be used as an initial value for positioning of the current location.

(Third embodiment)
The processing of the current position calculation unit 11, the position registration unit 13, the initial position management unit 14, the current position management unit 15, and the current position display unit 16 of the first embodiment and the second embodiment is realized by a program. Also good.

  FIG. 12 is a block diagram illustrating a configuration of a mobile terminal according to the third embodiment.

  As shown in FIG. 12, the mobile terminal 1 according to the third embodiment includes a CPU 20, a main storage device 21, an auxiliary storage device 22, a recording medium interface device 23, a recording medium 24, and a wireless unit 12. And the database 17 are connected via the internal bus 30.

  The recording medium 24 includes functions of the current position calculation unit 11, the position registration unit 13, the initial position management unit 14, the current position management unit 15, and the current position display unit 16 according to the first embodiment and the second embodiment. A program for realizing is recorded. The program recorded on the recording medium 24 is read into the main storage device 21 by the CPU 20 via the storage medium interface device 23. The CPU 20 executes processing according to the program read into the main storage device 21. The recording medium 24 may be a magnetic disk, a semiconductor memory, an optical disk, or other recording medium.

DESCRIPTION OF SYMBOLS 1 Mobile terminal 2 Wireless base station 3 Assist server 4 GPS satellite 11 Current position calculation part 12 Wireless part 13 Position registration part 14 Initial position management part 15 Current position management part 16 Current position display part 17 Database 20 CPU
21 Main storage device 22 Auxiliary storage device 23 Recording medium interface device 24 Recording medium

Claims (20)

If a signal transmitted from a radio base station is received, location registration means for performing location registration with the radio base station;
Current position management means for storing a base station position, which is a position of the radio base station, acquired from a radio base station registered in the past, associating with the radio base station, and storing as a base station position list;
It manages the initial position that is the initial value for calculating the current position, and when the position registration to a new radio base station is performed, the base station position of the radio base station is recorded in the base station position list If so, initial position management means for updating the initial position to the base station position;
Current position calculation means for performing an operation for calculating the current position using a received radio wave from a GPS satellite, using the initial position as an initial value;
A mobile terminal. The initial position management means includes
Further, the initial position error, which is an error of the initial position, is managed, and when the initial position error exceeds a predetermined threshold, a base station position is acquired from a radio base station that is currently registered, and the initial position error is acquired. 2. The mobile terminal according to claim 1, wherein the position is updated to the base station position, and the initial position error is updated to a distance reached by a transmission signal of a radio base station. The initial position management means includes
When the position registration to a new radio base station is performed, if the base station position of the radio base station is not recorded in the base station position list, the initial position error is updated and the initial position error is updated. The mobile terminal according to claim 2. The initial position management means includes
When updating the initial position error while leaving the initial position as it is, a distance that is twice the distance that the signal of the radio base station that sets the base station position as the initial position reaches is added to the initial position error. The mobile terminal according to claim 3. The initial position management means includes
4. When updating the initial position error while leaving the initial position as it is, a distance twice as long as a signal of a radio base station to be newly registered reaches is added to the initial position error. 5. Mobile terminal.   When the current position calculation means calculates the current position, the current position is associated with the radio base station that has performed position registration when calculating the current position and the radio base station position of the radio base station. The mobile terminal according to claim 1, wherein a history to be recorded is used as the base station position list. The initial position management means includes
7. The device according to claim 1, wherein when the location registration unit performs location registration with a radio base station in a predetermined country by international roaming, the initial location is updated to a predetermined specific location in the predetermined country. Mobile terminal. A current position display means for displaying a current position of the mobile terminal;
The current position display means displays the initial position managed by the initial position management means as the current position until the current position calculation means calculates the current position. The mobile terminal according to item. The base station position, which is the position of the radio base station, acquired from the radio base station registered in the past, is associated with the radio base station, and accumulated as a base station position list,
If the base station position of the radio base station is recorded in the base station position list when performing location registration with a new radio base station, the initial position is updated to the base station position, and the current position is updated. Manage the initial position to be the initial value for calculating
A GPS positioning method, wherein the initial position is used as an initial value, and a calculation for calculating a current position is performed using radio waves received from a GPS satellite. Furthermore, the initial position error that is an error of the initial position is managed,
When the initial position error is equal to or greater than a predetermined threshold, the base station position is acquired from the radio base station that is currently registered, and the initial position is updated to the base station position. The GPS positioning method according to claim 9, wherein the GPS positioning method is updated to a distance that the transmission signal of the base station reaches.   When performing position registration with a new radio base station, if the base station position of the radio base station is not recorded in the base station position list, the initial position error is updated and the initial position error is updated. Item 11. The GPS positioning method according to Item 10.   When updating the initial position error while leaving the initial position as it is, a distance that is twice the distance that the signal of the radio base station that sets the base station position as the initial position reaches is added to the initial position error. The GPS positioning method according to claim 11.   12. When updating the initial position error while leaving the initial position as it is, a distance twice as long as a signal of a radio base station to be newly registered reaches is added to the initial position error. GPS positioning method.   When calculating the current position, a history of recording the current position, the radio base station that performed position registration when calculating the current position, and the radio base station position of the radio base station in association with each other, The GPS positioning method according to claim 9, wherein the GPS positioning method is used as the base station position list. The base station position is obtained by performing location registration with the radio base station from which the signal is received and associating the base station location, which is the location of the radio base station, acquired from the radio base station with the location registered in the past, If the base station location of the radio base station is recorded in the base station location list when the location is registered in a new radio base station and registered in the base station location list, the initial location is set to the base station location. Update the initial position for calculating the current position, manage the initial position, and use the initial position as the initial value to calculate the current position using the received radio wave from the GPS satellite A mobile terminal that performs the computation;
A radio base station that provides the base station location when requested by the mobile terminal;
A GPS positioning system. The mobile terminal is
Further, the initial position error, which is an error of the initial position, is managed, and when the initial position error exceeds a predetermined threshold, the base station position is acquired from the radio base station registered at the current position, and the initial position is determined. The GPS positioning system according to claim 15, wherein the GPS positioning system is updated to the base station position and the initial position error is updated to a distance reached by a transmission signal of a radio base station. The mobile terminal is
When performing position registration with a new radio base station, if the base station position of the radio base station is not recorded in the base station position list, the initial position error is updated and the initial position error is updated. Item 17. The GPS positioning system according to Item 16. The mobile terminal is
When updating the initial position error while leaving the initial position as it is, a distance that is twice the distance that the signal of the radio base station that sets the base station position as the initial position reaches is added to the initial position error. The GPS positioning system according to claim 17. The mobile terminal is
18. When updating the initial position error while leaving the initial position as it is, a distance twice as long as a signal of a radio base station to be newly registered reaches is added to the initial position error. GPS positioning system. The mobile terminal is
When calculating the current position, a history of recording the current position, the radio base station that performed position registration when calculating the current position, and the radio base station position of the radio base station in association with each other, The GPS positioning system according to any one of claims 15 to 19, which is used as the base station position list.

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