JP2009033621A - Mobile terminal, method of detecting locations of base stations and mobile terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile terminal and method of detecting locations of base stations and the mobile station with and by which the locations can be highly accurately detected than the prior art. <P>SOLUTION: The present invention relates to a mobile terminal which exchanges signals using a predetermined modulation scheme with three or more base stations, including a communication section for exchanging signals with the base stations and a control section for controlling the communication section, wherein, based on the signals exchanged with the base stations by the communication section, the control section calculates a plurality of circles with a communicable range as a radius, around locations of the base stations and based on the signal modulation scheme and detects a center position of a superimposed area of the respective circles. <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 moving device, and the position of the mobile device is measured by measuring the radio field intensity of three or more surrounding base stations by the PHS terminal. When the position is within a preset allowable error range from the preset base position, it is determined that the device is at the base. The PHS terminal converts the measured radio field intensity from the three base stations into an estimated distance from each base station, obtains a circle drawn around the position of each base station from the estimated distance, and intersects the circles. Measure position from range.
JP 2007-43343 A

  By the way, the above-mentioned prior art uses a PHS terminal to receive radio waves from about 3 to 10 base stations, and a circle drawn around the position of the base station from the estimated distance calculated based on the radio field intensity. Since the position of the mobile device equipped with the PHS terminal is measured from the circle crossing range, the average error is 100 to 200 m when the number of base stations is small. In addition, in order to improve the accuracy of the above prior art, it is necessary to increase the accuracy of measuring the radio field intensity, and for that purpose, a dedicated terminal is required.

  The present invention has been made in view of the above-described circumstances, and provides a mobile terminal, a base station, and a mobile terminal position detection method capable of detecting a position with higher accuracy than in the past.

  In order to achieve the above object, according to the present invention, as a first means for solving a mobile terminal, a mobile terminal that transmits and receives signals using a predetermined modulation scheme with three or more base stations, And a control unit that controls the communication unit, and the control unit is configured to center the position of each base station based on a signal that the communication unit transmits and receives to each base station. And a means for calculating a plurality of circles having a radius within the communicable range based on the signal modulation method and detecting the center position of the overlapping area of the circles.

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

  In the present invention, as a third solving means relating to the mobile terminal, in the first or second solving means, the communication unit performs signal transmission / reception via a communication channel with one base station, The base station employs a means of performing via a control channel.

  Also, in the present invention, as a first solving means related to a base station, a mobile terminal that transmits / receives signals to / from three or more base stations and a base station that transmits / receives signals using a predetermined modulation scheme, A communication unit that transmits / receives a signal to / from a terminal, and a control unit that controls the communication unit, wherein the control unit focuses on a position of each base station based on a signal that the communication unit transmits / receives to / from a mobile terminal. In addition, a plurality of circles having a radius within a communicable range based on a modulation scheme of a signal transmitted / received by the mobile terminal to / from each base station is obtained, and the center position of the overlapping area of each circle is detected as the position of the mobile terminal. Adopt means.

  In the present invention, as a second solving means related to a base station, in the first solving means, the communication unit transmits and receives the signal whose modulation method is changed according to a communication state to and from the mobile terminal, and the control unit Calculates a concentric circle smaller than the circle whose radius is a communicable range based on a modulation scheme having a narrower communicable range than a modulation scheme of a signal transmitted and received by the mobile terminal, and limits the overlapping area by the concentric circle Adopt the means.

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 and receives signals using a predetermined modulation scheme with three or more base stations,
Based on the signals transmitted to and received from each base station, the mobile terminal calculates a plurality of circles centered on the position of each base station and having a radius within the communicable range based on the signal modulation method. The center position is detected as the position of the mobile terminal.

  According to the present invention, in a mobile terminal that transmits / receives a signal using a predetermined modulation scheme with three or more base stations, the control unit transmits / receives the communication unit to / from each base station via the communication channel and the control channel. In order to detect the center position of the area where each circle overlaps (superimposition area) based on the signal, calculate a circle centered on the position of each base station whose radius is the communicable range of the signal based on the signal modulation method, The error range can be further reduced as compared with the position detection using only the radio field intensity of the conventional signal.

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 which is one of portable terminals.
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, and a control unit 4.

  The communication unit 1 transmits / receives various signals to / from the PHS base station through the communication channel and the control channel based on the control of the control unit 4. Note that the communication network configured by the PHS terminal A and the base station supports an adaptive modulation scheme that changes a modulation scheme of a signal transmitted / received via a communication channel according to a communication state. This adaptive modulation system is supported. The modulation method of the control channel remains QPSK (Quadrature Phase Shift Keying) and does not change.

The operation unit 2 includes various operation keys such as a power key, a numeric keypad, and various function keys. The operation unit 2 outputs a user operation instruction to these operation keys to the control unit 4.
The display unit 3 is, for example, a liquid crystal monitor or an organic EL monitor, and displays various screens composed of images and characters based on signals input from the control unit 4.

  The control unit 4 inputs and outputs signals to and from the internal memory composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the communication unit 1, the operation unit 2, and the display unit 3. Each interface circuit is configured to control the overall operation of the PHS terminal A based on a control program stored in the ROM, various signals received by the communication unit 1 and operation instructions received by the operation unit 2. The control program stored in the ROM includes a position detection program, and details of the position detection processing executed by the control unit 4 based on the position detection program will be described as the operation of the PHS terminal A below. 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, and 5. FIG.
FIG. 3 is a schematic diagram showing a position detection method when the modulation scheme of a signal communicated between the PHS terminal A and the base station B via a communication channel is other than 64QAM (Quadrature Amplitude Modulation). It is a schematic diagram which shows the position detection method in case the modulation system of the signal which the terminal A and the base station B communicate via a communication channel is 64QAM. FIG. 5 is a diagram showing an example of the communicable range of the upstream signal and downstream signal in the signal modulation scheme.

The PHS terminal A according to the present embodiment transmits / receives a signal to / from a plurality of base stations simultaneously through a control channel, and transmits / receives a signal to / from one location-registered base station through a communication channel.
And this PHS terminal A calculates the communicable range of a signal based on the modulation system of the signal transmitted / received via the control channel and the communication channel with three or more base stations, and uses the communicable range of this signal. The position of the PHS terminal A is detected.

  As shown in FIG. 3 and FIG. 4, the PHS terminal A transmits and receives signals (control signals) via the control channels with the base stations B, C, and D, to the base station B having the strongest signal reception strength of the control signals. On the other hand, location registration is performed, and signals (communication signals) are transmitted and received via the communication channel.

  First, the control unit 4 of the PHS terminal A acquires the base station IDs of the base stations B, C, and D based on the control signals that the communication unit 1 receives from the base stations B, C, and D, and the base station B , C, and D are acquired (step S1).

  Next, the control unit 4 determines whether or not the communication signal modulation method is 64QAM based on the communication signal received by the communication unit 1 from the base station B (step S2), and the communication signal modulation method is not 64QAM. Is determined (NO), the communication range of the downlink signal of the communication signal is communicable based on the current modulation method of the communication signal, and the communication is possible in the downlink signal of the modulation method whose communication range is narrower than the modulation method of the current communication signal. The communication range of the downlink signal of the control signals of the base stations C and D based on the range (communication range for area limitation) and the modulation method is calculated (step S3).

The area-limited communication possible range in step S3 will be described with reference to FIG.
For example, when the current modulation scheme is 16QAM, the communicable range of the 16QAM downlink signal is 249 m. Therefore, the communication range of the 32QAM downlink signal that is narrower than the communicable range of the 16QAM downlink signal is 192 m. This is an area-limited communication range.

Each communicable range in step S3 is calculated from the formula of Okumura-Sakai curve (PCS extended Sakai 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 according to the size of the city.

The above equation (1) calculates the signal propagation loss based on the correction value according to the frequency of the signal, the antenna height of the base station, the antenna height of the mobile station, the communication distance, and the size of the city that is the communication service area. This is the formula used to calculate.
In step S3, the control unit 4 inputs the propagation loss of the signal obtained from the PHS terminal A, the base stations B, C, and D to the propagation loss Lp of the above formula (1), so that the communication distance d, that is, the communication in the present invention. Calculate the possible range.

The propagation loss Lp can be calculated by inputting the reception sensitivity based on the modulation method as a parameter in the following equation (2).

Lp = equivalent isotropic radiated power−reception sensitivity based on modulation scheme + reception 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

The control unit 4 calculates the propagation loss Lp from the above equation (2) using the reception sensitivity based on the modulation method as a parameter, and inputs this propagation loss to the propagation loss Lp in the above equation (1), thereby the communication distance d ( The communicable range in the present invention can be calculated.
Note that the communicable range calculated based on each modulation scheme is shown in FIG.

  Based on the position of the base station B acquired in step S1 and the communicable range and communicable range for area limitation of the communication signal of the base station B calculated in step S3, the control unit 4 A limited area is calculated by subtracting a concentric circle whose radius is the communicable range for area limitation from the circle whose center is the position of the base station B whose radius is the communicable range (step S4), and the base station C acquired in step S1 , D and the base station C, the base station C having the radius of the communicable range of the downlink signal of the control signal of each of the base stations C and D based on the communicable range of the downlink signal of the control signal calculated in step S3 A circle whose center is the position of each of stations C and D is calculated (step S5).

  The control unit 4 calculates an area (superimposition area) in which a circle centered at the position of each of the base stations C and D having the radius of the limited area calculated in step S4 and the downlink signal of the control signal calculated in step S5 is overlapped (step S6) The center position of this overlapping area is detected as the position of the PHS terminal A (step S7).

The calculation of the overlapping area in step S6 and the detection of the center position of the overlapping area in step S7 will be described in detail with reference to FIG.
3 indicates that the PHS terminal A and the base stations B, C, and D exist at the positions shown in the drawing.

  Circles C1, C2, and C3 in FIG. 3 indicate circles having a radius within a communicable range based on the modulation method QPSK of the downlink signal of the control signal centering on the respective positions of the base stations B, C, and D. A circle T1 in FIG. 3 indicates a circle whose radius is a communicable range of a downstream signal of 16QAM that is a modulation method of the current communication signal centered on the position of the base station B, and a circle T2 has a modulation method of 32QAM. The communicable range of the downstream signal is a concentric circle with a circle T1 having a radius. The communicable range of the downlink signal with the modulation scheme of 32QAM, which is the radius of the circle T2, is the communicable range for area limitation in step S3.

  The superimposition area calculated by the control unit 4 in step S4 is a limited area obtained by subtracting the circle T2 from the circle T1, and an area in which diagonal lines overlapping the circle C2 and the circle C3 are drawn. In step S5, the control unit 4 The point P1, which is the center position of the area, is detected as the position of the PHS terminal A.

  The point P2 is the center position of the overlapping area of the circles C1, C2, and C3. There is a difference in the center position of the overlapping area between the point P2 and the point P1, and this difference is the difference between the control signal based on the modulation method. This is a difference in position detection accuracy between the case where only the communicable range is used and the case where the communicable range of the communication signal based on the modulation method is used.

  The PHS terminal A in FIG. 3 has a communicable range of 16QAM downlink signals of 249 m and a communicable range of 32 QAM downlink signals of 192 m, so that the radius of the circle T1 in FIG. The radius is 192 m, and it is possible to suppress position detection errors to 52 m or less, which is the distance of the area between the circle T1 and the circle T2.

  In addition, when the control unit 4 determines in step S2 that the modulation method of the communication signal received by the communication unit 1 from the base station B is 64QAM (YES), the control unit 4 satisfies the above equations (1) and (2). The communication range of the uplink signal of the communication signal of the base station B and the downlink signal of the control signals of the base stations C and D based on the modulation method is calculated (step S8).

  Based on the position of the base station B acquired in step S1 and the communicable range of the uplink signal of the base station B calculated in step 8, the control unit 4 sets the communicable range of the uplink signal of the communication signal as the radius. The circle of the base station B to be centered is calculated (step S9), the positions of the base stations C and D acquired in step S1 and the downlink signal communication range of the control signals of the base stations C and D calculated in step S8 Based on the above, a circle whose center is the position of each of the base stations C and D having a radius within the communicable range of the downlink signal of the control signal of each of the base stations C and D is calculated (step S10).

  The control unit 4 uses the circle whose center is the position of the base station B whose radius is the uplink signal of the communication signal calculated in step S9 and each position of the base stations C and D whose radius is the downlink signal of the control signal calculated in step S5. Is calculated (step S11), and in step 7, the center position of the overlap area is detected as the position of the PHS terminal A.

The calculation of the overlapping area in step S11 and the detection of the center position of the overlapping area in step S7 will be described in detail with reference to FIG.
4 indicates that the PHS terminal A and the base stations B, C, and D exist at the positions shown in the drawing.

  Circles C4, C5, and C6 in FIG. 4 indicate circles having a radius within a communicable range based on the modulation method QPSK of the downlink signal of the control signal centering on the positions of the base stations B, C, and D, respectively. A circle T3 in FIG. 4 indicates a circle whose radius is a communicable range of an uplink signal of a communication signal whose modulation scheme is 64QAM centered on the position of the base station B, and a circle T4 is centered on the position of the base station B. The communication possible range of the downlink signal of the communication signal whose modulation method is 64QAM indicates a circle with a radius.

  When the PHS terminal A transmits / receives a communication signal having a modulation scheme of 64QAM to / from the base station B via the communication channel, the superimposition areas calculated by the control unit 4 in step S11 are circle T3, circle C2, and This is an area in which the diagonal line where the circle C3 overlaps is drawn, and in step S7, the control unit 4 detects the position of the point P3 which is the center position of this overlapping area.

  Note that point P4 is the center position of the overlap area of circles T4, C5, and C6, and there is a difference in the center position of the overlap area between point P4 and point P3. This difference is a communication signal whose modulation method is 64QAM. Is a difference in position detection accuracy between the case where the downlink communicable range is used and the case where the modulation method uses the uplink communicable range of the communication signal of 64QAM.

  4, the communicable range of the 64QAM upstream signal is 65 m and the communicable range of the 64QAM downstream signal is 141 m. Therefore, the radius of the circle T3 in FIG. The radius is 141 m. By using the upstream signal of the communication signal, it is possible to suppress position detection errors to 65 m or less, which is the radius of the circle T3.

  As described above, according to the present embodiment, the control unit 4 can perform communication based on the position of each base station to which the communication unit 1 transmits and receives signals, the control signal received from each base station, and the modulation method of the communication signal. Since a circle overlap area based on the range is calculated and the center position of this overlap area is set as the position of the PHS terminal A, the error range is made smaller than in the conventional position detection using only the signal strength of the signal. In other words, it is possible to increase the accuracy of position detection.

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 position detection process is executed by the PHS terminal A, but the present invention is not limited to this.
For example, the base station B acquires information on the communicable range based on the positions of the base stations C and D that transmit and receive signals from the PHS terminal A and the modulation scheme of the control signal, and communicates with the information and the position of the base station B. The position of the PHS terminal A may be detected based on the communicable range of the signal.

(2) In the above embodiment, the signal communication range is calculated based on the modulation method, and the position is detected based on the calculated communication range. However, 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.

(3) In the above embodiment, the communicable range 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 range 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.

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

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 position detection method in case the modulation system of the signal which PHS terminal A and base station B which concern on one Embodiment of this invention communicate via a communication channel is other than 64QAM. It is a schematic diagram which shows the position detection method in case the modulation system of the signal which PHS terminal A and base station B which concern on one Embodiment of this invention communicates via a communication channel is 64QA. It is a figure which shows the communicable range of the upstream signal and downstream signal in the signal modulation system of PHS terminal A which concerns on one Embodiment of this invention.

Explanation of symbols

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

Claims (6)

A mobile terminal that transmits and receives a signal using a predetermined modulation scheme with three or more base stations,
A communication unit that transmits and receives signals to and from the base station;
A control unit for controlling the communication unit,
The control unit calculates a plurality of circles centered on the position of each base station and having a communicable range based on the modulation method of the signal as a radius based on signals transmitted and received by the communication unit with each base station. A portable terminal that detects the center position of the overlapping area of each circle. The communication unit transmits and receives the signal with a modulation scheme changed 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 range based on a modulation scheme having a narrower communicable range than the modulation scheme of the signal, and limits the overlapping area by the concentric circle. The mobile terminal according to claim 1.   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 / receives a signal using a predetermined modulation scheme to a mobile terminal that transmits / receives a signal to / from three or more base stations,
A communication unit that transmits and receives signals to and from the mobile terminal;
A control unit for controlling the communication unit,
The control unit has a radius within a communicable range based on a modulation scheme of a signal transmitted from and to each base station and centered on a position of each base station based on a signal transmitted and received by the communication unit to and from the mobile terminal. A base station characterized in that a plurality of circles are obtained and the center position of the overlapping area of each circle is detected as the position of the mobile terminal. The communication unit transmits and receives the signal whose modulation method is changed according to a communication state with a mobile terminal,
The control unit calculates a concentric circle smaller than the circle having a communicable range based on a modulation scheme having a narrower communication range than a modulation scheme of a signal transmitted and received by the mobile terminal, and limits the overlapping area by the concentric circle. The base station according to claim 4, wherein: 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 the signals transmitted to and received from each base station, the mobile terminal calculates a plurality of circles centered on the position of each base station and having a radius within the communicable range based on the signal modulation method. A position detection method characterized by detecting the center position of the mobile phone as the position of the mobile terminal.

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