JP2009081686A - Portable terminal, base station and location detection method of portable terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal, base station and location detection method of the portable terminal which enable detection of a location of the portable terminal more highly accurately than the prior art by calculating a communicable distance of another signal in accordance with an environment where a signal is propagated. <P>SOLUTION: A portable terminal comprises: a communication section which exchanges a signal, modulated according to a predetermined modulation system with three or more base stations; a storage section which stores a plurality of propagation models each indicating a propagation environment of the modulated signal for each combination of the base stations and location information of the base stations; and a control section which controls the communication section and the storage section, wherein the control section specifies a propagation model corresponding to a combination of the base stations based on the modulated signal, calculates a communicable distance of the signal on the basis of the above propagation model, calculates a circle with the above communicable distance as a radius and a location of each base station as a center, respectively, to obtain a superimposing area in which the circles are overlapped, and detects a center position of the superimposing area as a location of the portable terminal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a portable terminal such as a portable telephone or a PHS (Personal Handy-phone System) terminal, a base station, and a position detection method for the portable terminal.

  In Patent Document 1 below, movement by PHS can accurately search for the position of a moving device such as a truck or a cargo handling pallet by accurately estimating an allowable error and accurately estimating an unloading time. A device location search method is disclosed.

In this position search method, a PHS terminal is attached to a mobile device, the PHS terminal calculates an estimated distance from each base station from the radio field intensity of signals from three or more neighboring base stations, and determines the position of each base station. A plurality of circles having the estimated distance as a radius is obtained as the center, and the position of the mobile device attached to the PHS terminal is obtained from the intersection range of these circles.
Then, when the position of the mobile device is within a preset allowable error range from the preset base position, it is determined that the mobile device is at the base position.
JP 2007-43343 A

  By the way, in the above prior art, the position of the PHS terminal is detected by calculating the estimated distance from each base station based on the radio field intensity of the signal. Since the degrees are different, if the estimated distance is simply calculated based on the radio wave intensity in the same manner, there is a problem that a difference occurs in the calculated estimated distance.

  The present invention has been made in view of the above-described circumstances, and conventionally calculates an appropriate communicable distance (corresponding to the estimated distance) of a signal transmitted and received by a mobile terminal or a base station according to an environment in which the signal propagates. An object of the present invention is to provide a mobile terminal, a base station, and a mobile terminal position detection method capable of detecting the position of the mobile terminal with higher accuracy.

  In order to achieve the above object, in the present invention, as a first solving means for a mobile terminal, a communication unit that transmits and receives a signal modulated with a predetermined modulation scheme with three or more base stations, and a propagation environment of the signal A storage unit that stores a plurality of propagation models for each combination of the base stations and stores position information of the base station, and a control unit that controls the communication unit and the storage unit, the control unit Specifies a propagation model corresponding to the combination of the base stations based on the signal, calculates a communicable distance of the signal based on the propagation model, sets the communicable distance as a radius, A method is employed in which circles centered on the position are calculated, overlap areas where the circles overlap are obtained, and the center position of the overlap area is detected as the position of the mobile terminal.

  In the present invention, as the second solving means relating to the mobile terminal, in the first solving means, the control unit changes to another propagation model when there is no overlapping area, and based on the propagation model. The superimposition area is obtained, and the propagation model is stored in the storage unit.

  In the present invention, as a third solving means relating to the mobile terminal, in the first or second solving means, the communication unit transmits and receives the signal for changing a modulation scheme according to a communication state with a base station, and The control unit employs means for calculating a concentric circle smaller than the circle having a communicable distance based on a modulation method having a communication range narrower than the modulation method of the signal, and limiting the overlapping area by the concentric circle.

  In the present invention, as a fourth solving means related to the mobile terminal, in any of the first to third solving means, the communication unit performs signal transmission / reception via a communication channel with one base station, The other base station adopts a means of performing via a control channel.

Further, in the present invention, as a first solving means related to a base station, a mobile terminal communicating with three or more base stations and a base station that transmits and receives a signal modulated by a predetermined modulation method,
A communication unit that transmits and receives signals to and from the mobile terminal;
A storage unit that stores a plurality of propagation models indicating propagation environments of signals transmitted and received by the mobile terminal for each combination of base stations with which the mobile terminal communicates, and stores position information of each base station;
A control unit for controlling the communication unit and the storage unit,
The control unit acquires communication information regarding a base station with which the mobile terminal communicates from the mobile terminal via the communication unit and a signal modulation method in communication, and the communication information and the communication unit transmit and receive with the mobile terminal. Based on the signal, a propagation model corresponding to a combination of base stations with which the portable terminal stored in the storage unit communicates is specified, and a communicable distance of a signal transmitted and received by the portable terminal with each base station based on the propagation model And calculating a circle around the position of each base station as a radius and calculating the overlap area where each circle overlaps, and detecting the center position of the overlap area as the position of the mobile terminal Adopt the means to do.

  In the present invention, as the second solving means relating to the base station, in the first solving means, when there is no overlapping area, the control unit changes to another propagation model, and based on the propagation model. The superimposition area is obtained, and the propagation model is stored in the storage unit.

  In the present invention, as a third solving means related to a base station, in the first or second solving means, the communication unit transmits and receives the signal for changing a modulation scheme according to a communication state with a mobile terminal, The control unit employs means for calculating a concentric circle smaller than the circle having a communicable distance based on a modulation method having a communication range narrower than the modulation method of the signal, and limiting the overlapping area by the concentric circle.

  Furthermore, in the present invention, as a first solving means related to the position detection method, there is provided a position detection method for a mobile terminal that transmits / receives a signal using a predetermined modulation scheme with three or more base stations, and the mobile terminal Based on a signal transmitted to and received from each base station, a communicable distance is calculated based on a propagation model and a modulation method. The communicable distance is set as a radius, and a plurality of circles are calculated with the position of each base station as a center. Then, a means is adopted in which a superposition area where each circle overlaps is obtained and the center position of the superposition area is detected as the position of the mobile terminal.

  According to the present invention, since a communicable distance of an appropriate signal is calculated according to an environment in which the signal propagates, position detection with higher accuracy than before can be performed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to a PHS (Personal Handy-phone System) terminal that is one of portable terminals and a position detection method thereof.
FIG. 1 is a functional block diagram of the PHS terminal A according to the present embodiment. As shown in FIG. 1, the PHS terminal A includes a communication unit 1, an operation unit 2, a display unit 3, a storage unit 4, and a control unit 5.

  The communication unit 1 transmits / receives various signals to / from the PHS base station via the communication channel and the control channel based on the control of the control unit 5. And the communication network comprised by this PHS terminal A and a base station respond | corresponds to the adaptive modulation system which changes the modulation system of the signal (communication signal) transmitted / received via a communication channel according to a communication state, The communication unit 1 supports this adaptive modulation method.

The operation unit 2 includes various operation keys such as a power key, a numeric keypad, and various function keys, and outputs user operation instructions for these operation keys to the control unit 5.
The display unit 3 is, for example, a liquid crystal monitor or an organic EL monitor, and displays various screens including images and characters based on signals input from the control unit 5.

  The storage unit 4 includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM stores a predetermined control program executed by the control unit 5, and the RAM is a work area when the control unit 5 executes the control program. Further, the ROM stores a CS selection list in which a propagation model indicating a signal propagation environment is registered for each combination of base stations.

  The control unit 5 performs the overall operation of the PHS terminal A based on a predetermined control program stored in advance in the ROM of the storage unit 4, various operation instructions received by the operation unit 2, and various signals input from the communication unit 1. To control. Note that the control program stored in the ROM includes a position detection program, and details of the position detection processing executed by the control unit 5 based on the position detection program will be described below as the operation of the PHS terminal A. To do.

Next, the position detection process of the PHS terminal A configured as described above will be described in detail with reference to the flowchart of the operation of the PHS terminal A shown in FIG. 2, and FIGS. 3, 4, 5, 6, and 7. FIG.
FIG. 3 is a schematic diagram illustrating a CS selection list stored in the storage unit 4, and FIG. 4 is a diagram illustrating a communicable distance of an uplink signal and a downlink signal for each signal modulation method. FIG. 5 is a schematic diagram illustrating position detection in a wireless communication system including the present PHS terminal A, base station B, base station C, and base station D.

  FIG. 6 is a schematic diagram showing the communicable distance of the communication signal from the base station CS1 and the communicable distance of the control signal from the base station CS2 calculated when the PHS terminal A uses the large city model for the propagation model. FIG. 7 is a schematic diagram showing the communicable distance of the communication signal from the base station CS1 and the communicable distance of the control signal from the base station CS2 calculated when the PHS terminal A uses the suburban model as the propagation model. It is.

In general, a PHS terminal transmits / receives a signal to / from a plurality of base stations at the same time via a control channel, and transmits / receives a signal to / from a single registered base station via a communication channel.
In this PHS terminal A, the communicable distance of the signal is calculated based on the modulation method of the signal transmitted / received via the control channel and the communication channel with three or more base stations and the propagation model of the CS selection list stored in the storage unit 4 The position of the PHS terminal A is detected based on the communicable distance of this signal.

The control unit 5 of the PHS terminal A measures the electric field strength of a control signal received by the communication unit 1 from a plurality of base stations located in the vicinity via the control channel, and the measured electric field strength is registered for each base station. A CS (Cell Station) list is created and stored in the storage unit 4 (step S1), and the communication unit 1 is registered in order to register the location with the base station B having the strongest signal reception intensity based on the CS list. Send a control signal.
Based on the CS list, the control unit 5 selects base stations as CS1, CS2, and CS3 in descending order of electric field strength (step S2). It is assumed that base station B is selected as CS1, base station C is selected as CS2, and base station D is selected as CS3.

  The control unit 5 determines whether the positions of the base stations B, C, and D that are CS1, CS2, and CS3 are already stored in the storage unit 4 (step S3), and “NO” in step S3. When the determination is made, the positions of the base station B, base station C, and base station D stored in the dedicated server are acquired via the base station B, and the combination of base stations selected as CS1, CS2, and CS3 is supported. (Step S4), the location of the base station B is stored in the storage unit 4, and the location of the base station C as CS2 and the location of the base station D as CS3 and the propagation model are registered in the CS selection list. (Step S5).

Details of the CS selection list will be described with reference to FIG.
FIG. 3 shows a CS selection list when CS1 is a base station B. A propagation model is registered for each combination of base stations CS2 and CS3. CS numbers of a plurality of base stations are registered in CS2 and CS3. In addition, latitude / longitude is registered as the position of each base station.

  The propagation model includes a large city model and a suburb model, and “3” is registered in the CS selection list, and “0” is registered in the suburb model. The value of this propagation model is a correction value CM [dB], which is one of the official parameters of the Okumura-Kashiwa curve (PCS extended Kashiwa model) shown in the following formula (1) used for calculation of the signal communicable distance. Applied. A detailed description of the formula of the Okumura-Kashiwa curve (PCS extended kite model) shown in Equation (1) will be given later.

  After the process of step S5, the control unit 5 reads information on the modulation scheme of the communication signal transmitted and received by the communication unit 1 and the base station B of CS1 stored in the storage unit 4 (step S6). The information on the modulation method is information that the control unit 5 stores the modulation method in the storage unit 4 based on the communication signal transmitted / received by the communication unit 1, and the communication of the downstream signal of the communication signal in step S9. Used when calculating the possible distance.

  When the control unit 5 determines “YES” in step S3, that is, when the positions of the base station B, the base station C, and the base station D and the propagation model are already registered in the CS selection list of the storage unit 4. In step S6, the process of step S6 is executed.

  After the process of step S6, the control unit 5 registers the communicable distance of the downlink signal of the control signal transmitted and received between the base station C being CS2 and the base station D being CS3 and the communication unit 1 in the CS selection list. Calculation is performed based on the value of the propagation model and the modulation method (step S7). The modulation method of the control channel is QPSK (Quadrature Phase Shift Keying) and does not change.

The communicable distance of the downlink signal of the control signal in step S7 is calculated based on the formula of Okumura-Kashiwa curve (PCS extended kite model) shown in the following formula (1).
Lp = 46.3 + 33.9 logf−13.82 hb-a (hm) + (44.9−6.55 loghb) logd + CM (1)
In the above equation (1), Lp is propagation loss [dB], f is frequency [MHz], hb is base station antenna height [m], hm is mobile station antenna height [m], and d is communication distance [km]. , A (hm) is a correction term for the mobile station antenna height, and CM is a correction value [dB] of the propagation model.

  In step S7, the control unit 5 calculates the communication distance d by substituting the propagation loss into the propagation loss Lp of the above formula (1). The communication distance d is a communicable distance in the present embodiment.

The propagation loss substituted into the formula (1) is calculated by the control unit 5 by substituting the reception sensitivity based on the modulation method into the following equation (2).
Lp = equivalent isotropic radiated power−reception sensitivity based on modulation scheme + receive antenna gain (2)
The following is an example showing that the reception sensitivity differs depending on the modulation method.
Modulation method Reception sensitivity (dBuV)
BPSK 12.5
QPSK 16.0
8PSK 20.0
16QAM 22.0
32QAM 26.0
64QAM 28.0
FIG. 4 shows the communicable distance calculated for each modulation method when the propagation model is a suburban model based on the above formulas (1) and (2).

  After the process of step S7, the control unit 5 sets the base station C, which is CS2, and the base station D, which is CS3, as the centers, and sets the communicable distance of the downlink signal of the control signal calculated in step S7 as a radius. And a first overlapping area of the two circles is calculated (step S8).

  In addition, the circle centering on the position of the base station C which is CS2 in step S8 is the circle C2 in FIG. 5, and the circle centering on the position of the base station D which is CS3 is the circle C3 in FIG. The control unit 5 calculates the area where the circle C2 and the circle C3 overlap as the first overlapping area.

  Based on the modulation method of the communication signal read from the storage unit 4 in step S6 and the value of the propagation model registered in the CS selection list stored in the storage unit 4, the control unit 5 performs the above equations (1) and ( 2) Calculate the communicable distance of the downlink signal from the communication signal, calculate a circle (hereinafter referred to as an outer circle) centered on the position of the base station B while using the communicable distance as a radius, and the current communication signal Communication range is calculated from the above formulas (1) and (2) based on the modulation scheme having a shorter communicable distance than the modulation scheme and the propagation model value registered in the CS selection list stored in the storage unit 4 Then, a circle that is a concentric circle of the outer circle with the communicable distance as a radius (hereinafter, inner circle) is calculated (step S9).

  Note that the outer circle calculated in step 9 is the circle T1 in FIG. 5, and the inner circle is the circle T2 in FIG. 5 indicates an outer circle calculated by the control unit 5 when the communication signal modulation method is 16QAM and the propagation model is a suburban model. The circle T2 in FIG. 5 is calculated by the control unit 5 based on the modulation method 32QAM having a communication range narrower than 16QAM and the propagation model being a suburban model because the communication signal modulation method is 16QAM. Indicates the inner circle.

After step S9, the control unit 5 has an area (second overlap area) where the first overlap area calculated in step S8 overlaps the limited area obtained by subtracting the area surrounded by the inner circle from the outer circle. It is determined whether or not to perform (step S10).
When determining “NO” in step S10, the control unit 5 changes the propagation model from the large city model to the suburban model (step S11), and in step S9 based on the value “0” which is the value of the suburban model. The circle and inner circle are recalculated, and step S10 is executed again based on the recalculated outer circle and inner circle.
Note that the second overlapping area is an area indicated by hatching in FIG.

The process of step S10 will be described in detail with reference to FIG.
For example, when the communication signal modulation method is 16QAM, when the control unit 5 determines “NO” in the process of step S10, the propagation model is a large city model. When the communicable distance of the communication signal from CS1 becomes narrow, the communicable distance of this communication signal does not overlap with the communicable distance of the control signal from CS2 indicated by the dotted line arrow in FIG. 6, and there is no second overlapping area It is.

  Therefore, the control unit 5 changes the propagation model to the suburban model in step S11, and indicates the communicable distance of the communication signal from the 16QAM CS1 shown in FIG. The communicable distances of the control signals from CS2 overlap, and therefore the second overlap area is obtained in step S10.

  However, when the communicable distance of the communication signal that is the radius of the outer circle is calculated using the suburban model, a second overlapping area that is larger than necessary may be calculated. In step S13, the second overlapping area is calculated. When the center position is detected as the position of the PHS terminal A, a difference from the actual position of the PHS terminal A becomes large.

When it determines with "YES" in step 10, the control part 5 records the propagation model used for calculation of an outer circle and an inner circle in step S9 to a CS selection list (step S12), and 2nd superimposition area The center position is calculated as the position of the PHS terminal A, and the position of the PHS terminal A is displayed on the display unit 3 using a map so that the user can easily visually recognize the position. (Step S13). Note that the position of the PHS terminal A calculated in step S13 is the center point P1 of the second overlapping area indicated by hatching in FIG.
Then, the control unit 5 outputs the CS selection list stored in the storage unit 4 to an external dedicated server via the communication unit 1 (step S14).

  As described above, according to the present embodiment, the storage unit 4 stores the CS selection list in which the propagation model is registered for each combination of base stations with which the communication unit 1 transmits and receives signals, and the control unit 5 A communicable distance of the control signal is calculated based on the value of the propagation model, and the communicable distance of the control signal is set as a radius, and a circle centered on the base station C of CS2 and the base station D of CS3 overlaps. A superimposition area is obtained, the outer circle and the inner circle centered on the base station B of CS1 are calculated based on the propagation model, a second superimposition area is obtained based on the outer circle and the inner circle, and the second superimposition area is obtained. Since the center position of the area is detected as the position of the PHS terminal A, it is possible to detect a position with higher accuracy than before by calculating an appropriate signal communicable distance according to the environment in which the signal propagates.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.

(1) In the above embodiment, the communicable distance of the signal is calculated using the large city model and the suburban model as the propagation model, but the present invention is not limited to this.
For example, it is possible to calculate a communicable distance of a communication signal based on a more appropriate value by using a more subdivided value of a large city model according to the city scale. The difference in the position of the PHS terminal A detected based on the second overlap area calculated using the outer circle is smaller.

(2) In the above embodiment, the position detection process is executed by the PHS terminal A, but the present invention is not limited to this, and the base station may detect the position of the PHS terminal A.
For example, the base station B that is CS1 obtains the position of the base station C that is CS2 and the base station D that is CS3, the modulation scheme of the control signal, and the CS selection list from the PHS terminal A, and the position of CS2 and CS3 The position of the PHS terminal A may be detected based on the modulation method of the control signal, the propagation model of the CS selection list, the position of the base station B, and the modulation method of the communication signal.

(3) In the above embodiment, when it is determined as “NO” in Step 10, that is, when the second overlapping area does not exist, the propagation model is changed, and the outer circle and the inner center around the base station B of CS 1 are changed. Although the second overlapping area is obtained by recalculating the circle, the present invention is not limited to this.
For example, based on the changed propagation model, a circle around the base station C of CS2 and the base station D of C3 may be calculated to obtain the second overlap area.

(4) In the above embodiment, the communicable distance of the signal is calculated based on the modulation method, and the position is detected based on the calculated communicable distance, but the present invention is not limited to this.
For example, the communicable range of the signal may be calculated based on the reception bandwidth of the signal, FER (frame error rate), and the like instead of the modulation scheme, and the position of the PHS terminal A may be detected.

(5) In the above embodiment, the communicable distance is calculated using the formula of Okumura-Kashiwa curve (PCS extended kite model), but the present invention is not limited to this.
For example, the communicable distance may be calculated using the Walfisch-Ikegami equation or Sakagami equation instead of the Okumura-Kashiwa curve (PCS extended Kashiwa model), and the position of the PHS terminal A may be detected.

(6) In the above embodiment, the position detection is performed mainly using the communicable distance of the downlink signal, but the present invention is not limited to this.
For example, the position detection may be performed using the communicable distance obtained from the modulation scheme of the uplink signal.

It is a functional block diagram of PHS terminal A concerning one embodiment of the present invention. It is a flowchart of operation | movement of the PHS terminal A which concerns on one Embodiment of this invention. . It is a schematic diagram which shows the CS selection list which the memory | storage part 4 of the PHS terminal A which concerns on one Embodiment of this invention memorize | stores. It is a figure which shows the communicable distance of the upstream signal and downstream signal for every modulation system of the signal of PHS terminal A which concerns on one Embodiment of this invention. It is a schematic diagram which shows the position detection in the radio | wireless communications system comprised by PHS terminal A, base station B, base station C, and base station D which concerns on one Embodiment of this invention. It is a schematic diagram which shows the communicable distance of the communication signal from base station CS1 and the communicable distance of the control signal from base station CS2 which PHS terminal A which concerns on one Embodiment of this invention calculates based on a big city model. It is a schematic diagram which shows the communicable distance of the communication signal from base station CS1 and the communicable distance of the control signal from base station CS2 which PHS terminal A which concerns on one Embodiment of this invention calculates based on a suburb model.

Explanation of symbols

  A ... PHS terminal, B, C, D ... base station, 1 ... communication unit, 2 ... operation unit, 3 ... display unit, 4 ... storage unit, 5 ... control unit

Claims (8)

A communication unit that transmits and receives a signal modulated by a predetermined modulation method with three or more base stations;
A storage unit that stores a plurality of propagation models indicating the propagation environment of the signal for each combination of the base stations and stores positional information of the base stations;
A control unit for controlling the communication unit and the storage unit,
The control unit specifies a propagation model corresponding to the combination of the base stations based on the signal, calculates a communicable distance of the signal based on the propagation model, sets the communicable distance as a radius, and A mobile terminal characterized by calculating a circle centered on a position of a base station, obtaining an overlap area where the circles overlap, and detecting the center position of the overlap area as the position of the mobile terminal.   The said control part changes to another propagation model, when the said overlapping area does not exist, calculates | requires the said overlapping area based on the said propagation model, and memorize | stores the said propagation model in the said memory | storage part. Item 2. A portable terminal according to Item 1. The communication unit transmits and receives the signal for changing a modulation scheme according to a communication state with a base station,
The control unit calculates a concentric circle smaller than the circle whose radius is a communicable distance based on a modulation method having a communication range narrower than the modulation method of the signal, and limits the overlapping area by the concentric circle. The portable terminal according to claim 1 and 2.   The mobile terminal according to claim 1 or 2, wherein the communication unit performs signal transmission / reception with one base station via a communication channel and with another base station via a control channel. A base station that transmits and receives a signal modulated by a predetermined modulation method with a mobile terminal that communicates with three or more base stations;
A communication unit that transmits and receives signals to and from the mobile terminal;
A storage unit that stores a plurality of propagation models indicating propagation environments of signals transmitted and received by the mobile terminal for each combination of base stations with which the mobile terminal communicates, and stores position information of each base station;
A control unit for controlling the communication unit and the storage unit,
The control unit acquires communication information regarding a base station with which the mobile terminal communicates from the mobile terminal via the communication unit and a signal modulation method in communication, and the communication information and the communication unit transmit and receive with the mobile terminal. Based on the signal, a propagation model corresponding to a combination of base stations with which the portable terminal stored in the storage unit communicates is specified, and a communicable distance of a signal transmitted and received by the portable terminal with each base station based on the propagation model And calculating a circle around the position of each base station as a radius and calculating the overlap area where each circle overlaps, and detecting the center position of the overlap area as the position of the mobile terminal A base station characterized by:   The said control part changes to another propagation model, when the said overlapping area does not exist, calculates | requires the said overlapping area based on the said propagation model, and memorize | stores the said propagation model in the said memory | storage part. Item 6. The base station according to Item 5. The communication unit transmits and receives the signal for changing a modulation method according to a communication state with a mobile terminal,
The control unit calculates a concentric circle smaller than the circle whose radius is a communicable distance based on a modulation method having a communication range narrower than the modulation method of the signal, and limits the overlapping area by the concentric circle. The base station according to claim 5 and 6. A method of detecting a position of a mobile terminal that transmits and receives a signal using a predetermined modulation scheme with three or more base stations,
Based on signals transmitted and received by the mobile terminal to and from each base station, a communicable distance is calculated based on a propagation model and a modulation method, and the communicable distance is set as a radius and a position of each base station is set as a center, and a plurality of distances are calculated. A position detection method characterized in that a circle is calculated, an overlapping area where each circle overlaps is obtained, and a center position of the overlapping area is detected as a position of a mobile terminal.

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