JP5181985B2 - Reception strength measurement method, receiver, and mobile station positioning system - Google Patents

Description

  The present invention relates to a reception intensity measurement method for detecting reception intensity when receiving radio waves, a receiver capable of measuring reception intensity of radio waves received by the reception intensity measurement method, and the receiver as a plurality of base stations. Alternatively, the present invention relates to a mobile station positioning system that is included as a mobile station and can calculate the position of the mobile station.

  A method has been proposed in which a radio wave transmitted from a transmitter is received, and a distance between the receiver and the transmitter is obtained based on the received intensity of the received radio wave. At this time, the position of the receiver can be calculated, for example, by calculating the distance between each of the plurality of transmitters at a known position and the receiver.

  At this time, as a means for reducing the influence of fluctuations caused by radio wave interference on the reception intensity and measuring the reception intensity with high accuracy, a method of measuring the reception intensity a plurality of times at one reception can be mentioned. Specifically, a method that averages the results obtained by multiple measurements, or analyzes the results obtained by multiple measurements using a frequency distribution and uses the value measured at the highest frequency. Can be considered.

  However, neither of these methods can satisfactorily remove the influence of radio wave interference. In other words, when averaging, it is impossible to completely remove the influence of fluctuations in reception strength due to interference, and even when analyzing by frequency distribution, the value where fluctuations in reception strength due to interference occur most frequently. May be selected as being measured at

  The present invention has been made against the background of the above circumstances, and the purpose of the present invention is to reduce the influence of fluctuations of radio wave interference on the reception intensity when measuring the reception intensity of the received radio wave. Measure strength.

  In Patent Document 1, the influence of the reflected wave that reaches the receiver after being reflected is reduced based on the delay time when the reflected wave reaches the receiver, so that the reflected wave and the receiver directly. A technique for reducing interference (multipath) with an incoming direct wave and using only the received intensity of the direct wave is disclosed.

JP 2000-75012 A

  In order to achieve such an object, the present inventors have conducted various experiments and examinations. When the reception results of radio waves are varied, the results obtained by a plurality of measurements are analyzed by frequency distribution. It has been found that the frequency distribution of the wave, that is, the radio wave whose reception intensity is to be measured hardly changes with the change of the reception condition, while the frequency distribution of the reception intensity value resulting from the interference changes with the change of the reception condition.

The present invention has been made based on such knowledge, and the invention according to claim 1 is (a) a reception intensity measuring method for measuring the reception intensity of a received radio wave, and (b) the radio wave. A measurement condition setting step for setting a plurality of measurement conditions received with different influences of interference in radio wave propagation to each other, and (c) for each of the plurality of measurement conditions set by the measurement condition setting step And receiving the value of the reception intensity of the radio wave for each predetermined measurement interval in a predetermined reception time interval, dividing the reception intensity into the intervals, and calculating the distribution of the measurement frequency for each of the intervals and strength measurement step, and calculating (d) is corrected measurement frequency from the distribution of the measured frequency to the value of the reception intensity calculated by the reception intensity measurement process, the influence of the reception intensity of the radio wave received is reduced The average of the corrected measurement frequency, or by using the largest compensation measurement frequency, characterized by having a a receiving strength calculation step of calculating the corrected reception intensity of the radio wave to be received.

The invention according to claim 7 is (a) a receiver including a reception intensity measurement unit for measuring the reception intensity of a received radio wave, and (b) the reception intensity measurement unit transmits the radio wave. A measurement condition setting means for setting a plurality of measurement conditions to be received with different influences of interference in radio wave propagation for reception, and (c) for each of the plurality of measurement conditions set by the measurement condition setting means, A reception intensity that measures the value of the reception intensity of the radio wave at a predetermined measurement interval in a predetermined reception time interval, divides the reception intensity into sections, and calculates a distribution of measurement frequencies for each of the sections a measuring means is calculated by (d) the receiving intensity measurement unit, the distribution of the measurement frequency for a value of the reception intensity of each of the plurality of measurement conditions, the influence of the variation of the reception intensity of the radio wave to be received is reduced By calculating respective correction measurement frequency to the value of the reception intensity, calculates a correction distribution, the average of the correction measurement frequency in the corrected distribution, or by using the largest compensation measurement frequency of electric waves received And a reception intensity calculating means for calculating a corrected reception intensity.

  In the invention according to claim 8, (a) radio waves are transmitted / received between a plurality of base stations located at known positions and a movable mobile station, and based on a reception result in the transmission / reception. A mobile station positioning system for calculating a position of the mobile station, wherein (b) one of the plurality of base stations and the mobile station is the receiver according to claim 7, and the other is the receiver And (c) calculating the distance between each of the plurality of base stations and the mobile station based on the corrected reception intensity measured by the reception intensity measurement unit, And a positioning unit that calculates the position of the mobile station based on the above.

According to the first aspect of the present invention, the measurement condition setting step sets a plurality of different measurement conditions that are received with different influences of interference in the propagation of the radio wave for receiving the radio wave, and the reception intensity measurement For each of the measurement conditions set by the measurement condition setting step, the value of the radio wave reception intensity is measured at a predetermined measurement interval at a predetermined reception time interval, and the reception intensity is A distribution of measurement frequencies for each of the sections is calculated, and a distribution of measurement frequencies is calculated for each of the plurality of measurement conditions by the reception intensity measurement step. from by calculating respective correction measurement frequency of impact is the reduction of fluctuations in the reception intensity of the radio wave to be received for the value of the reception intensity It calculates a correction distribution, the average of the correction measurement frequency in the corrected distribution, or, since the corrected reception strength of electric waves received with the highest correction measurement frequency is calculated, reception strength for each of the different measurement conditions The corrected reception intensity obtained by calculation based on the above can be obtained as the reception intensity with reduced influence of radio wave interference.

Further preferably, in the reception intensity calculation step, among the distributions calculated by the reception intensity measurement step for each of the measurement conditions set by the measurement condition setting step, the measurement frequency at the same reception intensity is the smallest. The correction distribution is calculated by using the measurement frequency as the correction measurement frequency for the reception intensity, and the correction reception intensity is calculated based on the calculated correction distribution. In this case, the correction distribution is calculated using only the received intensity value measured using the received intensity value detected in common for each of the plurality of measurement conditions in the received intensity calculating step. The corrected reception intensity can be obtained as the reception intensity with reduced influence of radio wave interference based on the correction distribution.

  Preferably, the measurement condition setting step sets the plurality of measurement conditions as receiving radio waves using a plurality of antennas provided at different positions. In this way, the effect of radio wave interference is reduced by the corrected reception intensity obtained by a predetermined calculation method based on the reception intensity of radio waves received by a plurality of antennas provided at different positions. Received strength.

  Preferably, the measurement condition setting step sets the plurality of measurement conditions as receiving radio waves of a plurality of types of frequencies. In this way, the corrected received intensity calculated by a predetermined calculation method based on each of the received intensities of the radio waves having a plurality of frequencies transmitted at different frequencies is used as the received intensity with reduced influence of the radio wave interference. Can be obtained.

Further preferably, the reception intensity calculation step is obtained by multiplying the distribution calculated by the reception intensity measurement step for each of the measurement conditions set by the measurement condition setting step by a measurement frequency at the same reception intensity. The correction distribution is calculated by setting the obtained value as the correction measurement frequency for the reception intensity, and the correction reception intensity is calculated based on the calculated correction distribution. In this case, the correction distribution is calculated using only the received intensity value measured using the received intensity value detected in common for each of the plurality of measurement conditions in the received intensity calculating step. The corrected reception intensity can be obtained as the reception intensity with reduced influence of radio wave interference based on the correction distribution.

Also preferably, in the distribution calculated by the reception intensity measurement step for each of the measurement conditions set by the measurement condition setting step, the reception intensity calculation step has a measurement frequency at the same reception intensity as the measurement condition. If the difference between the maximum value and the minimum value of the measurement frequency under the plurality of measurement conditions is less than a predetermined threshold, the average value of the measurement frequency under each of the plurality of measurement conditions is While the measurement frequency is corrected for the reception intensity, the measurement frequency at the same reception intensity is zero in any of the measurement conditions, or the difference between the maximum value and the minimum value of the measurement frequency in the plurality of measurement conditions is a predetermined value. in case where the threshold value or more, the correction distribution by assuming no corrective measurement frequency in each of the plurality of measurement conditions To calculate, said calculating a corrected reception intensity based on the calculated the corrected distribution, characterized by. According to this configuration, the correction distribution can be calculated by removing the reception intensity having a high measurement frequency only under a specific measurement condition from the correction measurement frequency, and performing the correction reception based on the correction distribution. The intensity can be obtained as a reception intensity with reduced influence of radio wave interference.

According to the invention of claim 7, the receiver includes a reception intensity measurement unit for measuring the reception intensity of the received radio wave, and the reception intensity measurement unit receives the radio wave. A measurement condition setting means for setting a plurality of measurement conditions to be received with different influences of interference in radio wave propagation, and a value of the reception intensity of the radio wave for each of the plurality of measurement conditions set by the measurement condition setting means Is measured at predetermined measurement intervals in a predetermined reception time interval set in advance, the reception intensity is divided into sections, and a reception intensity measuring means for calculating a distribution of measurement frequencies for each of the sections, and the reception intensity is calculated by measuring means, the distribution of the measurement frequency for a value of the reception intensity of each of the plurality of measurement conditions, receiving a correction measurement frequency of impact is the reduction of fluctuations in the reception intensity of the radio wave to be received By calculating respectively the intensity values, calculates a correction distribution, the average of the correction measurement frequency in the corrected distribution, or by using the largest compensation measurement frequency, calculates a corrected reception strength of electric waves received And receiving intensity calculation means. Therefore, it is possible to obtain a corrected reception intensity with reduced interference of radio waves received by the receiver as radio wave reception intensity.

  Further, according to the mobile station positioning system of claim 8, any one of the plurality of base stations having the receiver of claim 7 and the mobile station transmits radio waves transmitted from the other. Since it receives, it is possible to obtain the corrected reception intensity that reduces the interference of the received radio wave as the reception intensity of the radio wave, and each of the plurality of base stations based on the corrected reception intensity that reduces the interference of the radio wave by the positioning unit Since the distance between the mobile station and the mobile station is calculated, and the position of the mobile station is calculated based on the distance, the position of the mobile station can be calculated with high accuracy.

  Preferably, the mobile station positioning system receives a radio wave having a frequency at which an index indicating radio wave interference in communication between the receiver and a transmitter that transmits a radio wave to the receiver satisfies a predetermined requirement. Since the positioning condition setting unit is set as the measurement condition, a frequency for transmitting and receiving radio waves between the receiver and the transmitter is set in advance as the measurement condition using a frequency with low radio wave interference. Therefore, it is possible to obtain the reception intensity with reduced influence of radio wave interference.

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

  FIG. 1 is a diagram showing an outline of a mobile station positioning system 8 of the present invention. In FIG. 1, a mobile station positioning system 8 includes, for example, a mobile station 10 that can move in a plane parallel to the figure, and four base stations 12A, 12B, 12C, and 12D (hereinafter referred to as positions) whose positions are known. When not distinguishing each of the base stations, it is referred to as “base station 12”), and a server 14 that can communicate with the base station 12 through, for example, a communication cable 18 or the like. In the mobile station positioning system 8, for example, coordinates as shown in FIG. 1 are defined so that the positions of the mobile station 10 and the base station 12 can be represented.

  The mobile station 10 and the base station 12 can wirelessly communicate with each other. Similarly, each of the plurality of base stations 12 can wirelessly communicate with each other. For example, the identification code included in the radio wave transmitted by each of the mobile station 10 and the base station 12 can identify whether the radio wave is transmitted by the mobile station 10 or which base station 12 when the radio wave is received. It is said that. Further, by having a common encoding and decoding procedure, information can be exchanged between the mobile station 10 and the base station 12 and between the plurality of base stations 12.

  FIG. 2 is a functional block diagram for explaining a main part of the functions of the mobile station 10. As shown in FIG. 2, the mobile station 10 has an antenna 22 for transmitting / receiving radio waves, a radio unit 24 having a function for transmitting / receiving radio waves, and a control unit 26 for controlling the radio unit 24. Functionally.

  Here, in the base station 12 that receives the radio wave transmitted from the mobile station 10, the base station 12 that is at an equal distance from the mobile station 10 receives the radio wave with the same reception intensity regardless of the direction from the mobile station 10. Therefore, the antenna 22 is preferably an antenna having no directivity.

  The radio unit 24 transmits and receives radio waves in the mobile station 10 and is switched between a transmission state and a reception state by a control unit 26 described later. At the time of transmitting a radio wave, the radio unit 24 transmits the radio wave by the antenna 22 according to the control content instructed by the control unit 26, that is, the content of the signal wave, the frequency of the carrier wave, the transmission output, and the like. As described above, the wireless unit 24 includes a carrier wave generation circuit, a modulator, a transmission amplifier, and the like. The radio unit 24 amplifies the radio wave received by the antenna 22 when receiving the radio wave, and extracts a signal wave by performing a predetermined demodulation process or the like. That is, the radio unit 24 includes a reception amplifier, a demodulator, and the like.

  The control unit 26 controls the operation of the mobile station 10. Specifically, the control unit 26 processes information received by the radio unit 24, operates the radio unit 24, more specifically, transmits output, Control of the transmission frequency and the like, generation of a signal wave transmitted wirelessly, and the like are performed. The control unit 26 is implemented by, for example, a known microcomputer. The wireless unit 24 and the control unit 26 have a function as a transmitter.

  FIG. 3 is a functional block diagram illustrating the main part of the functions of the base station 12. As shown in FIG. 3, the base station 12 has a plurality of antennas for transmitting and receiving radio waves. Specifically, in the example of FIG. 3, three antennas of a first antenna 32a, a second antenna 32b, and a third antenna 32c are used. 32 (hereinafter referred to as “antenna 32” when the first antenna 32a to the third antenna 32c are not distinguished from each other). The three antennas 32 are disposed at a distance corresponding to at least λ / 2 when the wavelength of the radio wave to be received, that is, the radio wave transmitted from the mobile station 10 is λ. As described above, according to the plurality of antennas 32 that are spaced apart by λ / 2 or more, the influence of interference in the propagation of radio waves between the mobile station 10 and the base station 12 is received differently.

  The base station 12 functions as a radio unit 34 and a reception intensity detection unit 38, a distribution generation unit 40, a fluctuation removal unit 42, a corrected reception intensity calculation unit 44, a control unit 36, and the like provided corresponding to the plurality of antennas 32. Have. The base station 12 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM to perform a signal according to a program stored in the ROM in advance. By performing processing, these functions are performed. In the present embodiment, as shown in FIG. 3, the first radio unit 34a, the second antenna 32a, the second antenna 32b, and the third antenna 32c are respectively corresponding to the first antenna 32a, the second antenna 32b, and the third antenna 32c. Includes three radio units, a radio unit 34b and a third radio unit 34c, and three reception intensity detection units 38, a first reception intensity detection unit 38a, a second reception intensity detection unit 38b, and a third reception intensity detection unit 38c. (Hereinafter referred to as “wireless unit 34” when the first wireless unit 34a through the third wireless unit 34c are not distinguished, and when the first received strength detector 38a through the third received strength detector 38c are not distinguished, A reception intensity detector 38 ”). Further, the base station 12 includes a clock 48 and a communication interface 60.

  The radio unit 34 performs transmission / reception of radio waves in the base station 12 similarly to the radio unit 24 of the mobile station 10 described above, and is switched between a transmission state and a reception state by a control unit 36 described later. At the time of transmitting the radio wave, the radio unit 34 transmits the radio wave by the antenna 32 corresponding to each of the radio units 34 according to the control content instructed by the control unit 36, that is, the content of the signal wave, the frequency of the carrier wave, the transmission output and the like. As described above, the wireless unit 34 includes a carrier wave generation circuit, a modulator, a transmission amplifier, and the like. In addition, the radio unit 34 amplifies the radio wave received by the antenna 32 when receiving the radio wave, and extracts a signal wave by performing predetermined demodulation processing or the like. That is, the radio unit 34 includes a reception amplifier, a demodulator, and the like.

  The control unit 36 controls the operation of the base station 12. Specifically, the control unit 36 takes out information by the wireless unit 34, processes information obtained from the server 14 to be described later, or operates the base station 12 according to a command. Or change. The operation of the wireless unit 34, more specifically, control of transmission output and transmission frequency, generation of a signal wave transmitted wirelessly, and the like are performed. The control unit 36 is implemented by, for example, a known microcomputer. The wireless unit 34, the control unit 36, and the like have a function as a receiver.

  The control unit 36 has a measurement condition setting unit 46 functionally. The measurement condition setting unit 46 sets a plurality of measurement conditions when creating a distribution of measurement frequencies for the measurement value of the reception intensity of the radio wave received by the distribution generation unit 40 described later. The measurement frequency is, for example, the number of measurements at a predetermined measurement interval. Specifically, in this embodiment, the measurement condition setting unit 46 sets the plurality of measurement conditions to receive radio waves received using a plurality of antennas 32 arranged at different positions. That is, in this embodiment, radio waves transmitted from the mobile station 10 are received by the radio units 34 corresponding to the plurality of antennas using the plurality of antennas 32. The operation of the measurement condition setting unit 46 corresponds to a measurement condition calculation process.

  The reception intensity detection unit 38 measures the reception intensity of the radio wave received by each of the corresponding radio units 34. For example, a clock supplied from a clock 48 described later in a predetermined reception time interval set in advance. Based on the signal, the value of the received intensity of the radio wave received at every predetermined measurement interval is detected. The reception intensity of the radio wave is, for example, an RSSI (Receive Signal Strength Indicator) which is an index obtained by quantifying the intensity of the received radio wave. Generally, the reception intensity of the radio wave is determined by a predetermined number of 256 stages by an AD converter. Converted. Further, the predetermined measurement interval is set, for example, so as to be a sufficient number of samples when the correction distribution is generated in the fluctuation removing unit 42 described later. Also, the detection of the value of the reception intensity by the reception intensity detection unit 38 is performed in a reception time interval that is a predetermined time. This reception time interval is set to be the same as the transmission time, for example, corresponding to the length of the radio wave transmission time by the mobile station 10, for example. When the concept including the reception intensity detection unit 38 and the distribution generation unit 40 is a reception intensity measurement unit 52, the operation by the reception intensity measurement unit 52 corresponds to the reception intensity measurement process.

  The distribution generation unit 40 generates, for each reception intensity detection unit 38, a histogram of the distribution of detection frequencies for the reception intensity values of the radio waves measured by the reception intensity detection units 38 in the reception time interval.

  FIG. 5 is a diagram for explaining an example of the reception intensity measured by the reception intensity detection unit 38 corresponding to the radio unit 34 of the radio wave received by any one of the radio units 34. The thick line in FIG. 5 represents the reception intensity. For example, the reception intensity fluctuates as surrounded by the broken line a due to the reception wave reaching the base station 12 due to interference. For example, an average value of reception intensities detected at a plurality of times within the reception time interval T may be used as the reception intensity of the radio wave received in the reception time interval T illustrated in FIG. In the example of FIG. 5, fluctuations in reception intensity as indicated by a broken line a occur, and an average Pa including these fluctuations is calculated. However, since the fluctuation of the reception intensity as shown by the broken line a in FIG. 5 is caused by interference as described above, the average excluding this influence is calculated as Pb in FIG. desirable.

  FIG. 6 shows a case where the distribution generation unit 40 generates the reception intensity measured by the reception intensity detection unit 38 corresponding to the radio unit 34 of the radio wave received by any of the radio units 34 in a certain reception time interval. It is a figure explaining an example of the histogram of distribution to be performed. The horizontal axis represents the received intensity value, and the vertical axis represents the frequency at which the received intensity value was measured (detected). The value of the reception intensity on the horizontal axis is divided into sections (classes) according to an appropriate size width. The measurement frequency on the vertical axis is the measurement frequency (frequency) for each of the sections, that is, the total of the measurement frequencies of the received intensity belonging to the section. As shown by the broken line a in FIG. 5 described above, when receiving the influence of the fluctuation of the reception strength, the group 90 corresponding to the value of the reception intensity when not affected by the fluctuation of the reception intensity, A group 92 corresponding to the value of the received intensity when affected by fluctuations appears. As the reception intensity of the radio wave received in the reception time interval in which the distribution of FIG. 6 is generated, for example, the median value of the reception intensity interval corresponding to the frequency measured most frequently in the distribution may be used. In such a case, if the reception strength is greatly affected, the section of the reception strength corresponding to the most frequently measured frequency in the distribution is affected by the fluctuation of the reception strength as shown in FIG. In some cases, it does not appear in the group 90 corresponding to the value of the reception strength when there is not, but appears in the group 92 corresponding to the value of the reception strength when affected by the fluctuation of the reception strength.

  Returning to FIG. 3, the fluctuation removing unit 42 calculates in advance the distribution of the detection frequency for the reception intensity value of the radio wave measured by each of the reception intensity detection units 38 generated by the distribution generation unit 40. It calculates by the method and calculates the correction distribution of the received radio wave. In this correction distribution, the influence of fluctuations in reception intensity due to the influence of radio wave interference or the like is reduced by a calculation method described later. A calculation method in the fluctuation removing unit 42 in this embodiment will be described below. The fluctuation removing unit 42 determines, for the plurality of distributions of the reception intensity of the radio wave generated by the distribution generation unit 40, the measurement frequency with the smallest measurement frequency for the section of the reception intensity among the plurality of distributions. The process of setting the correction measurement frequency for each section is represented by each of the received intensity sections, specifically, in 256 steps from 0 to 255, and when the section width is 8, each of the 32 sections. Do about. Then, the correction measurement frequency for each received intensity section thus obtained is calculated as a corrected distribution that is a distribution with respect to the received intensity.

  The corrected received intensity calculation unit 44 calculates the corrected received intensity of the radio wave received by the base station 12 based on the correction distribution calculated by the fluctuation removing unit 42. Specifically, for example, in the histogram calculated as the correction distribution by the fluctuation removing unit 42, the median value of the received intensity categories that generated the most corrected measurement frequency is calculated as the corrected received intensity.

  Assuming that the concept including the fluctuation removing unit 42 and the corrected received intensity calculating unit 44 is a received intensity calculating unit 54, the operation by the received intensity calculating unit 54 corresponds to the received intensity calculating step.

  The operation of the fluctuation removing unit 42 will be specifically described with reference to FIG. FIG. 7 shows a histogram of reception intensity detected by the plurality of reception intensity detection units 38 generated by the distribution generation unit 40. For example, FIG. 7A shows the first reception intensity detection unit 38a, (B) represents a second received intensity detector 38b, and (c) represents a received intensity value (received intensity interval) that has a common histogram for the received intensity detected by the third received intensity detector 38c. This is shown using the horizontal axis. That is, it is obtained by receiving radio waves from the mobile station 10 by each of a plurality of different antennas 34a, 34b, 34c corresponding to a plurality of measurement conditions. As described above, since the antennas 34a, 34b, and 34c are installed at different positions, the influence of radio wave interference is different. That is, the frequency distribution at the intensity of the desired wave is almost common, but the frequency distribution in the portion affected by the interference differs depending on each antenna.

  The fluctuation removing unit 42 determines, for the plurality of distributions in FIGS. 7A to 7C, the measurement frequency with the smallest measurement frequency for the reception intensity section among the plurality of distributions for the reception intensity section. The process of setting the correction measurement frequency is performed for all reception intensity sections. Then, the histogram represented by the correction measurement frequency for each received intensity section thus obtained is calculated as a corrected distribution that is a distribution with respect to the received intensity. For example, for the received intensity section S1, the measurement frequency is T1A in the distribution of FIG. 7A, the measurement frequency T1B is 0 in the distribution of FIG. 7B, and in the distribution of FIG. Since the measurement frequency is T1C, 0, which is the lowest measurement frequency among these, is set as the corrected measurement frequency for the section S1 of the reception intensity. Similarly, for the received intensity section S2, the measurement frequency is T2A in the distribution of FIG. 7A, the measurement frequency is T2B in the distribution of FIG. 7B, and the measurement is in the distribution of FIG. The frequency is T2C. Neither of these is 0, but T2B, which is the least measurement frequency, is the correction measurement frequency for the reception intensity section S2. Further, for the reception intensity section S3, the measurement frequency T3A in the distribution of FIG. 7A, the measurement frequency T3C in the distribution of FIG. 7C is 0, and the measurement frequency T3C in the distribution of FIG. Since the frequency is T3B, 0, which is the smallest measurement frequency among these, is set as the corrected measurement frequency for the section S3 of the received intensity. Also, in any of the distributions of FIGS. 7A to 7C, the number of times of correction measurement frequency of reception intensity at which the measurement frequency is 0 is 0. This is expressed in each of the sections having a predetermined section width with respect to the reception strength, specifically, in the 256 steps from 0 to 255 as in the case of FIG. By executing for each of the 32 sections, it is possible to obtain the corrected measurement frequency count for each received intensity section. Further, a correction distribution can be obtained by using this correction measurement frequency as a histogram for the reception intensity. In this way, fluctuations in reception intensity due to radio wave interference and the like are unlikely to appear in all different reception intensities, so the plurality of measurement conditions are compared, and each of the reception intensity values corresponds to the plurality of measurement conditions. By setting the smallest measurement frequency value among the plurality of received intensity distributions as the corrected measurement frequency, the corrected measurement frequency can be reduced from the influence of fluctuations in the radio wave reception intensity.

  The communication interface 60 transmits and receives information from the base station 12 to the server 14 and other base stations 12 via the communication cable 18. For example, information about the value of the corrected reception intensity calculated by the reception intensity calculation unit 44 is transmitted from each base station 12 to the server 14 via the communication interface 60. In addition, a command related to the operation of the base station 12 and the mobile station 10 is transmitted from the server 14 to the base station 12 and received via the communication interface 60.

  FIG. 4 is a functional block diagram for explaining a main part of the functions of the server 14. As shown in FIG. 4, the server 14 includes a storage unit 66 for storing necessary information, a positioning unit 68 for performing calculation for calculating the position of the mobile station 10, and a base connected by a communication cable 18. A communication interface 64 for performing information communication with the station 12 is functionally provided. The server 14 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. By performing the processing, necessary operations and the like are executed.

  The communication interface 64 transmits / receives information from the server 14 to other base stations 12 via the communication cable 18 in the same manner as the communication interface 60 of the base station 12 described above.

  The storage unit 66 stores information required for positioning by a positioning unit 68 described later. FIG. 8 shows an example of information stored in the storage unit 66. The general relationship between the propagation distance D (m) of a radio wave transmitted with a predetermined output and the reception intensity (for example, RSSI) of the radio wave is shown. It is shown. This relationship is obtained in advance experimentally or by simulation and stored in the storage unit 58. Specifically, the propagation distance D of the radio wave corresponds to the distance between the mobile station 10 that transmits the radio wave and the base station 12 that receives the radio wave.

  The positioning unit 68 calculates the position of the mobile station 10 based on the corrected reception intensity calculated by the corrected reception intensity calculation unit 44 of each base station 12 and the position information of each base station 12 known in advance.

  First, the positioning unit 68 calculates the distance between each base station 12 and the mobile station 10 based on the relationship between the propagation distance of the radio wave stored in the storage unit 66 and the reception intensity of the radio wave. Specifically, each base corresponding to the corrected reception intensity calculated by the corrected reception intensity calculation unit 44 of each base station 12 from the relationship between the propagation distance of the radio wave and the reception intensity of the radio wave as shown in FIG. The distance between the station 12 and the mobile station 10 is calculated.

  Subsequently, the position of the mobile station 10 is calculated based on the distance between each base station 12 and the mobile station 10 and the position information of each base station 12 known in advance.

FIG. 9 is a diagram for explaining the principle of calculation of the position of the mobile station 10 by the positioning unit 66. The coordinates representing the position of the mobile station 10 are (x, y), and the coordinates representing the position of the first ordinary base station 12A, which is the base station receiving the radio wave from the mobile station 10, are (x _B1 , y _B1 ). The coordinates representing the position of the second ordinary base station 12B are (x _B2 , y _B2 ), the coordinates representing the position of the third ordinary base station 12C are (x _B3 , y _B3 ), and the position of the fourth base station 12D. If the coordinates are (x _B4 , y _B4 ), these relationships are obtained by the following equation (1). Note that the arrangement of base stations 12 in FIG. 11 is different from that in FIG. 1 for the sake of simplicity.
(x _B1 -x) ² + (y _B1 -y) ² = r ₁ ²
(x _B2 -x) ² + (y _B2 -y) ² = r ₂ ²
(x _B3 -x) ² + (y _B3 -y) ² = r ₃ ²
(x _B4 -x) ² + (y _B4 -y) ² = r ₄ ² (1)
Here, r ₁ , r ₂ , r ₃ and r ₄ (m) are respectively from the first ordinary base station 12A, the second ordinary base station 12B, the third base station 12C, and the fourth ordinary base station 12D. The corrected reception intensity calculated by the corrected reception intensity calculation unit 44 of each base station 12 from the relationship between the propagation distance of the radio wave stored in the storage unit 66 and the reception intensity of the radio wave, which is the distance to the mobile station 10 Is a distance calculated as a value corresponding to. The positioning unit 66 calculates the position (x, y) of the mobile station 10 by solving the equation (1). In solving the equation (1), it is not necessary to solve all the equations simultaneously, and the equation (1) may be solved by a minimum number of equations to calculate the solution. Specifically, when the mobile station 10 moves on the plane, the equation (1) may be an equation for solving the unknown position (x, y), that is, two unknowns. More than this formula, that is, a formula derived based on reception results at three or more base stations 12 may be used. Similarly, when the mobile station 10 moves in a three-dimensional space, the equation (1) is an equation for solving three unknowns corresponding to (x, y, z) representing the position of the mobile station. Four or more formulas, that is, formulas derived based on reception results at four or more base stations 12 are used.

  FIG. 10 is a flowchart for explaining an example of the control operation in the mobile station positioning system 8 of this embodiment. First, in step (hereinafter, “step” is omitted) SA1, an instruction for performing positioning of the mobile station 10 is issued from the server 14 to each of the base stations 12. This command is (1) a command for causing the mobile station 10 to transmit a radio wave for positioning to any one of the plurality of base stations 12 (hereinafter referred to as “representative base station”). A command to be transmitted from the radio unit 34 to the mobile station 10 and (2) a positioning radio wave transmitted from the mobile station 10 to each of the plurality of base stations 12 is received, and the reception intensity measurement unit 38 receives the reception intensity. And a command for causing the server 14 to transmit the detected reception intensity. Among these, the command (1) is such that the server 14 does not have a function for transmission / reception of radio waves for wireless communication, so the command from the server 14 to the mobile station 10 is any base station 12. The representative base station that is any one of the base stations 12 is, for example, a base station 12 that is arbitrarily selected.

  In SA2, each base station 12 waits for an SA1 command from the server 14 to be received. When the SA1 command from the server 14 is received, the determination at this step is affirmed and the subsequent SA3 is executed. On the other hand, if the SA1 command from the server 14 is not received, the determination in this step is denied, SA1 is repeatedly executed, and a standby is performed until the SA1 command from the server 14 is received.

  SA3 is a step executed when the determination of SA2 is affirmed, and it is determined whether or not the command (1) is received from the server 14 received at SA2. In the base station 12 that has received the command (1), that is, the representative base station, the determination in this step is affirmed and SA4 is executed. In addition, in the base station 12 that has not received the command (1) but has received only the command (2), the determination of this step is denied and transmitted from the mobile station 10 without executing SA4. Radio waves are received for positioning.

  In SA4, a command for causing the mobile station 10 to transmit a radio wave for positioning is transmitted to the mobile station 10 by radio. When the base station 12 has a plurality of antennas 32, this command may be performed by arbitrarily selecting any one antenna and using the antennas 32. After the command is transmitted to the mobile station 10, a radio wave for positioning transmitted from the mobile station 10 is received.

  In SA5, the mobile station 10 waits for a command (SA4 command) for transmitting a radio wave for positioning received. When the mobile station 10 receives a command for transmitting a radio wave for positioning, the determination in this step is affirmed and the subsequent SA6 is executed. On the other hand, if a command for transmitting a radio wave for positioning is not received, the determination in this step is denied, SA5 is repeatedly executed, and a command for transmitting a radio wave for positioning is received. Wait until

  In SA6 corresponding to the wireless unit 24 of the mobile station 10, radio waves for positioning are transmitted from the mobile station 10. Transmission of radio waves for this positioning is performed by a predetermined output.

  In SA7 corresponding to the radio unit 34, the reception intensity detection unit 38, etc. of each base station 12, a radio wave for positioning transmitted from the mobile station 10 is received, and the value of the reception intensity is determined in advance, for example. It is measured at every measurement interval. This reception is performed, for example, corresponding to a plurality of measurement conditions set in advance, and in the present embodiment, it is performed using antennas installed at a plurality of different positions. As described above, for example, RSSI for evaluating the reception strength in 256 levels is used as the reception strength. Data measured in this way is obtained in time series order, that is, as a value of reception intensity with respect to reception time.

  In SA8 corresponding to the distribution generation unit 40, for each of a plurality of measurement conditions, that is, for each reception intensity of radio waves received by a plurality of antennas 32, a histogram is obtained from the frequency distribution of the measurement frequency with respect to the reception intensity value, for example, as shown in FIG. A plurality of (a) to (c) are generated. In the present embodiment, the reception strength is RSSI represented by the 256-step index from 0 to 255 as described above, and the width of the section is 8. Therefore, the number of sections of the reception strength in the generated histogram The (histogram class) is 32.

  In SA9 corresponding to the fluctuation removal unit 42, a fluctuation removal routine for obtaining a correction distribution in which the influence of fluctuations in radio wave reception intensity is reduced is executed based on each of the plurality of histograms generated in SA8.

  FIG. 11 is a flowchart for explaining an example of the fluctuation removal routine. First, in SB1, the value of the variable S representing the received intensity interval (class) is initialized (in this case, 0). In the following, the received intensity interval for the variable S is referred to as a received intensity class S.

  Subsequently, in SB2, the measurement frequencies for the received intensity class S in each of the plurality of histograms generated in SA8 are compared, and the minimum value is selected to be the corrected measurement frequency.

  In SB3, it is determined whether or not the value of the reception strength class S is a preset maximum value Smax. In the present embodiment, since the reception strength section is 32 sections as described above, the maximum value Smax of the reception strength class S is 31. If the value of the reception strength class S is the maximum value set in advance, the determination in this step is affirmed and SB4 is executed. If the value of the reception strength class S is not the maximum value set in advance, the determination at this step is denied and SB5 is executed.

  In SB4, based on the corrected measurement frequency calculated in SB2 for each reception intensity class S, specifically, a histogram representing the corrected measurement frequency calculated in SB2 for each reception intensity section is generated as a correction distribution. .

  In SB5 executed when the determination of SB3 is denied, SB2 is executed again after 1 is added to S representing the received intensity class.

  Returning to FIG. 10, in SA10 corresponding to the corrected reception intensity calculation unit 44, the reception intensity of the radio wave received by the base station 12 based on the correction distribution generated in SA9, and the influence of fluctuations in the reception intensity. The corrected reception intensity, which is a value obtained by reducing the above, is calculated. Specifically, this corrected reception intensity is calculated as the average of the correction distribution.

  In SA11 corresponding to the communication interface 60 or the like, the value of the corrected received intensity calculated in SA10 is transmitted to the server 14 via the communication cable 18 or the like.

  In the SA 12 corresponding to the positioning unit 68 of the server 14 and the like, the correction reception intensity values of the radio waves from the mobile stations 10 in the plurality of base stations 12 transmitted in the SA 11 from the plurality of base stations 12 are stored in advance. The position of the mobile station 10 is calculated based on the information on the position of the existing base station 12. Specifically, for example, based on the relationship between the received power intensity and distance shown in FIG. 8 and the like, based on the corrected received intensity of radio waves from the mobile station 10 in each of the plurality of base stations 12, these base stations 12 And the distance between the mobile station 10 and the mobile station 10 are calculated. Then, based on the calculated distance r between each base station 12 and the mobile station 10 and information on the position of the base station 12 stored in advance, for example, a relational expression as shown in the expression (1) is obtained. The position of the mobile station 10 is obtained as a solution by deriving and solving the relational expression.

  According to the above-described embodiment, the measurement condition setting unit 46 (SA7) sets a plurality of different measurement conditions for receiving radio waves, and the reception intensity measurement unit 52 (the reception intensity detection unit 38, the distribution generation unit 40, SA7 and SA8), for each of the measurement conditions set by the measurement condition setting unit 46, the value of the radio wave reception intensity is measured at a predetermined measurement interval in a predetermined reception time interval and received. A histogram of the measurement frequency for the intensity interval is calculated, and the received intensity interval calculated by the received intensity measuring unit 54 by the received intensity calculating unit 54 (variation removing unit 42, corrected received intensity calculating unit 44, SA9, SA10). By calculating the distribution of the measurement frequency with respect to a predetermined calculation method stored in advance, the corrected reception intensity of the received radio wave is calculated. In, can be obtained as the reception intensity of the corrected reception intensities obtained are computed to reduce the effects of radio interference based on the reception strength for each of the different measurement conditions.

  In addition, according to the above-described embodiment, the reception intensity calculation unit 54 has the same reception intensity section in the histogram calculated by the reception intensity measurement unit 52 for each of the measurement conditions set by the measurement condition setting unit 46. The correction distribution is calculated by setting the measurement frequency with the least measurement frequency in the measurement frequency for the reception intensity section, and the correction reception intensity is calculated based on the calculated correction distribution. The unit 44 can calculate the correction distribution using only the received intensity value measured using the received intensity value detected in common for each of the plurality of measurement conditions, and based on the corrected distribution Thus, the corrected reception intensity can be obtained as a reception intensity with reduced influence of radio wave interference.

  Further, according to the above-described embodiment, the measurement condition setting unit 46 sets the plurality of measurement conditions as receiving radio waves using each of the plurality of antennas 32 provided at different positions. To obtain a corrected reception intensity calculated by a predetermined calculation method based on each of the reception strengths of the radio waves received by the plurality of antennas 32 respectively provided as a reception strength with reduced influence of radio wave interference. it can.

  In addition, according to the above-described embodiment, the base station 12 includes the antennas 32 installed at a plurality of different positions and the plurality of radio units 34 for receiving radio waves corresponding to the antennas, and further, the plurality of these units. Since the reception intensity measurement unit 38 capable of measuring the reception intensity of the radio wave received by the radio unit 34 is provided, the corrected reception intensity with reduced interference of the radio wave received according to the measurement condition set by the measurement condition setting unit 46 is set to the radio wave. Can be obtained as the received intensity.

  Further, according to the above-described embodiment, the mobile station positioning system 8 includes the antennas 32 installed at a plurality of different positions and the plurality of radio units 34 for receiving radio waves corresponding to the antennas, Further, since the plurality of base stations 12 including the reception intensity measuring unit 38 capable of measuring the reception intensity of the radio waves received by the plurality of radio units 34 receive the radio waves transmitted from the mobile station 10, The corrected reception intensity with reduced interference can be obtained as the radio wave reception intensity, and the positioning unit 68 determines whether the mobile station 10 and each of the plurality of base stations 12 are based on the corrected reception intensity with reduced radio wave interference. Since the distance is calculated and the position of the mobile station 10 is calculated based on the distance, the position of the mobile station 10 can be calculated with high accuracy.

  Subsequently, another embodiment of the present invention will be described. In the following description, portions common to the embodiments are denoted by the same reference numerals and description thereof is omitted.

  The present embodiment relates to another operation of the fluctuation removing unit 42. The fluctuation removing unit 42 is stored in advance as a distribution (histogram) of detection frequencies for the reception intensity values of the radio waves measured by the reception intensity detection units 38 generated by the distribution generation unit 40 as described above. The correction distribution of the received radio wave is calculated by the above calculation method.

  In the above-described embodiment, the fluctuation removing unit 42 has the smallest measurement frequency in the reception intensity section among the plurality of distributions for the plurality of histograms of the reception intensity of the radio wave generated by the distribution generation unit 40. The process of setting the measurement frequency as the corrected measurement frequency for the section of the received intensity is performed for all the received intensity sections, and the corrected measured frequency for each received intensity section is calculated as a correction distribution that is a distribution of the received intensity. did.

  In the present embodiment, the fluctuation removing unit 42 obtains the plurality of distributions of the reception intensity of the radio waves generated by the distribution generation unit 40 by multiplying the measurement frequencies in each of the plurality of distributions for the section of the reception intensity. The process of setting the obtained value as the correction measurement frequency for the reception intensity interval is expressed in all reception intensity intervals, specifically, in 256 steps from 0 to 255. The reception intensity interval is 32. In this case, it is performed for each of the 32 sections. And the correction | amendment measurement frequency with respect to the area of each received intensity | strength obtained is calculated as a correction distribution which is distribution with respect to received intensity.

  The operation of the fluctuation removing unit 42 in this embodiment will be specifically described with reference to FIG. 7, as described above, the distribution of a plurality of reception strengths generated by the distribution generation unit 40, for example, FIG. 7A shows the first reception strength detection unit 38a, and FIG. 7B shows the second reception strength detection unit. 38b and (c) show the distribution of the received intensity detected by each of the third received intensity detectors 38c, using a horizontal axis representing a common received intensity value (received intensity interval). Specifically, as in the above-described embodiment, this section is represented by 256 levels from 0 to 255, and when the section width is 8, it is set as 32 sections.

  The fluctuation removing unit 42 calculates a value obtained by multiplying a plurality of distributions in FIGS. 7A to 7C by a measurement frequency in each of the plurality of distributions for the reception intensity section. The process of setting the correction measurement frequency is performed for all reception intensity sections. Then, the correction measurement frequency for each received intensity section thus obtained is calculated as a corrected distribution that is a distribution with respect to the received intensity. For example, for the received intensity section S1, the measurement frequency is T1A in the distribution of FIG. 7A, the measurement frequency T1B is 0 in the distribution of FIG. 7B, and in the distribution of FIG. Since the measurement frequency is T1C, 0, which is a value obtained by multiplying these, is set as the corrected measurement frequency for the section S1 of the reception intensity. Similarly, for the reception intensity section S3, the measurement frequency T3A in the distribution of FIG. 7 (a), the measurement frequency T3C in the distribution of FIG. 7 (c) is 0, and in the distribution of FIG. 7 (b). Since the measurement frequency is T3B, 0 obtained by multiplying these is the correction measurement frequency for the section S3 of the received intensity. Further, in any of the distributions of FIGS. 7A to 7C, the corrected measurement frequency of the section of the reception intensity whose measurement frequency is 0 is 0. On the other hand, for the received intensity section S2, the measurement frequency is T2A in the distribution of FIG. 7A, the measurement frequency is T2B in the distribution of FIG. 7B, and the measurement is in the distribution of FIG. The frequency is T2C. Since these are not 0, T2A × T2B × T2C multiplied by these values is used as the correction measurement frequency for the reception intensity section S2. This is expressed in each of the sections having a predetermined section width with respect to the reception strength, specifically, in the same manner as in FIG. 6, the reception intensity is expressed in 256 stages from 0 to 255, and when the section width is 8, By executing for each of the 32 sections, it is possible to obtain the corrected measurement frequency count for each received intensity section. Further, a correction distribution can be obtained by using this correction measurement frequency as a histogram for the reception intensity. In this way, fluctuations in reception intensity due to radio wave interference and the like are unlikely to appear in all different reception intensities, so the plurality of measurement conditions are compared, and each of the reception intensity values corresponds to the plurality of measurement conditions. By setting the smallest measurement frequency value among the plurality of received intensity distributions as the corrected measurement frequency, the corrected measurement frequency can be reduced from the influence of fluctuations in the radio wave reception intensity.

  FIG. 12 is a flowchart for explaining an example of the operation of the fluctuation removing unit 42 in the present embodiment, that is, a flowchart for explaining an example of a fluctuation removing routine executed corresponding to SA9 in FIG. First, in SC1, the value of the variable S indicating the section (class) of received intensity is initialized (here, 0).

  Subsequently, in SC2, the measurement frequency with respect to the reception intensity class S in each of the plurality of histograms generated in SA8 is multiplied, and the product is calculated as the corrected measurement frequency.

  In SC3, it is determined whether or not the value of the reception strength class S is a preset maximum value Smax. If the value of the reception strength class S is the maximum value Smax of the reception strength class set in advance, specifically, for example, in this embodiment where 32 reception strength classes are set, the determination of this step is affirmative. SC4 is executed. If the value of the reception strength class S is not the preset maximum value, the determination at this step is denied and SC5 is executed.

  In SC4, based on the corrected measurement frequency calculated in SC2 for each reception intensity class S, a correction distribution that is a distribution of the correction measurement frequency with respect to the reception intensity is generated.

  In SC5 executed when the determination of SC3 is negative, 1 is added to the value S of the received intensity class, and then SC2 is executed again.

  According to the above-described embodiment, the reception intensity calculation unit 54 (variation removal unit 42, corrected reception intensity calculation unit 44, SA9, SA10) receives the reception intensity measurement unit for each of the measurement conditions set by the measurement condition setting unit 46. In the distribution calculated by 52, a correction distribution is calculated by setting a value obtained by multiplying the measurement frequency in the section of the same reception strength as the measurement frequency for the reception strength, and based on the calculated correction distribution Since the correction reception intensity is calculated, the correction distribution is calculated using only the reception intensity value measured using the reception intensity value detected in common for each of the plurality of measurement conditions, in other words. When the reception strength is 0 under any one of the measurement conditions, the correction distribution can be calculated with the correction reception strength as 0. Corrected reception strength based on the correction distribution can be obtained as the reception intensity effect with reduced interference of radio waves.

  The present embodiment relates to still another operation of the fluctuation removing unit 42. In the present embodiment, the fluctuation removing unit 42 has a plurality of distributions (histograms) of reception intensity of radio waves generated by the distribution generation unit 40 regardless of whether the measurement frequency in the same reception intensity category is the above measurement conditions. When the difference between the maximum value and the minimum value of the measurement frequency under the plurality of measurement conditions is not zero and is below a predetermined threshold, the average measurement frequency under each of the plurality of measurement conditions is corrected for the received intensity. The frequency processing is represented by all reception strength categories, specifically, for example, when the reception strength is expressed in 256 steps from 0 to 255, and the width of the reception category is 8, 32 categories. For each of these. Then, the obtained correction measurement frequency for each received intensity category is calculated as a corrected distribution that is a distribution with respect to the received intensity.

  The operation of the fluctuation removing unit 42 in this embodiment will be specifically described with reference to FIG. 7, as described above, a histogram (distribution) of a plurality of reception strengths generated by the distribution generation unit 40, for example, FIG. 7A shows the first reception strength detection unit 38a, and FIG. 7B shows the second reception strength. The distribution of the reception intensity detected by each of the third reception intensity detection units 38c and (c) is shown using the horizontal axis representing the common reception intensity value (reception intensity interval). Yes.

  The fluctuation removing unit 42 measures the measurement frequency for the plurality of distributions in FIGS. 7A to 7C with respect to the reception intensity interval which is not zero in any of the measurement conditions, and in the measurement conditions. When the difference between the maximum value and the minimum value of the frequency is below a predetermined threshold, the process of setting the average value of the measurement frequencies in each of the plurality of measurement conditions as the correction measurement frequency for the reception intensity is performed for all the reception intensity sections. Do. Then, the correction measurement frequency for each received intensity section thus obtained is calculated as a corrected distribution that is a distribution with respect to the received intensity. For example, for the reception intensity section S1, the measurement frequency T1B is 0 in the distribution of FIG. 7B, and for the reception intensity section S3, the measurement frequency T3A in the distribution of FIG. In the distribution of FIG. 7C, the measurement frequency T3C is 0, that is, the measurement frequency under any of the measurement conditions is 0. Therefore, the corrected measurement frequency is 0, respectively. Also, in any of the distributions of FIGS. 7A to 7C, the correction measurement frequency of the received intensity whose measurement frequency is 0 is also set to 0. On the other hand, for the received intensity section S2, the measurement frequency is T2A in the distribution of FIG. 7A, the measurement frequency is T2B in the distribution of FIG. 7B, and the measurement is in the distribution of FIG. The frequency is T2C. Since none of these is 0, it is determined whether or not the difference between the maximum value and the minimum value of the measurement frequency is below a predetermined threshold value. If this determination is affirmed, the average value of the measurement frequencies under each of the plurality of measurement conditions is set as the corrected measurement frequency for the received intensity. On the other hand, when the determination is negative, the correction measurement frequency is set to zero.

  Here, the predetermined threshold is set, for example, as a value obtained by multiplying the maximum value of the measurement frequency under a plurality of measurement conditions by 0.5. In the example of the reception intensity S2, if the measurement frequency in each distribution is T2C> T2A> T2B> 0, the maximum value and the minimum value of the measurement frequency are T2C and T2B, respectively. The fluctuation removing unit 42 determines whether or not the difference between the maximum value and the minimum value (T2C−T2B) is less than T2C / 2 obtained by multiplying the maximum value that is the predetermined threshold by 0.5. If the determination is affirmative, that is, if (T2C−T2B) <T2C / 2, the average of the plurality of measurement frequencies, that is, (T2A + T2B + T2C) / 3 is set as the corrected measurement frequency of the reception intensity S2. To do. On the other hand, when the determination is negative, that is, when (T2C−T2B) ≧ T2C / 2, the correction measurement frequency of the reception intensity S2 is set to zero. In this way, since the received intensity having a high measurement frequency only under specific measurement conditions is excluded from the corrected measurement frequency, the corrected measurement frequency can be reduced by the influence of fluctuations in the radio wave reception intensity.

  FIG. 13 is a flowchart for explaining an example of the operation of the fluctuation removing unit 42 in the present embodiment, that is, a flowchart for explaining an example of a fluctuation removing routine executed corresponding to SA9 of FIG. First, in SD1, the value of the variable S representing the received intensity interval (class) is initialized (in this case, 0).

  Subsequently, in SD2, it is determined whether or not any of the measurement frequencies for the received intensity class S in each of the plurality of histograms generated in SA8 is zero. If none of the measurement frequencies in the distribution corresponding to each of the plurality of measurement conditions is 0, the determination in this step is affirmed and SD3 is executed. If any of the measurement frequencies in the distribution corresponding to each of the plurality of measurement conditions is 0, the determination in this step is denied and SD5 is executed.

  In SD3, it is determined whether or not the difference between the maximum measurement frequency and the minimum measurement frequency among the measurement frequencies for the received intensity class S in each of the plurality of distributions generated in SA8 is below a predetermined threshold value. The The predetermined threshold is, for example, a value obtained by multiplying the maximum measurement frequency by 0.5. If the difference between the maximum measurement frequency and the minimum measurement frequency is below the predetermined threshold, the determination in this step is affirmed and SD4 is executed. On the other hand, if the difference between the maximum measurement frequency and the minimum measurement frequency exceeds a predetermined threshold value, or both are equal, the determination in this step is denied and SD5 is executed.

  In SD4, the corrected measurement frequency corresponding to the reception intensity class S is calculated as the average of the measurement frequencies for the reception intensity class S in each of the plurality of distributions generated in SA8.

  In SD5, the correction measurement frequency corresponding to the reception intensity class S is set to zero.

  In SD6, it is determined whether or not the value of the reception strength class S is a preset maximum value Smax. If the value of the reception strength class S is the maximum value Smax of the reception strength class set in advance, specifically, for example, in this embodiment where 32 reception strength classes are set, the determination of this step is affirmative. SD7 is executed. If the value of the reception strength class S is not the preset maximum value, the determination at this step is denied and SD8 is executed.

  In SD7, based on the corrected measurement frequency calculated in SD4 for each received intensity class S, a corrected distribution that is a distribution of corrected measured frequencies with respect to received intensity is generated.

  In SD8 executed when the determination of SD6 is denied, 1 is added to the value S of the received intensity class, and then SD2 is executed again.

  According to the above-described embodiment, the reception intensity calculation unit 54 (variation removal unit 42, corrected reception intensity calculation unit 44, SA9, SA10) receives the reception intensity measurement process for each of the measurement conditions set by the measurement condition setting unit 46. In the distribution calculated by 52, the measurement frequency in the section of the same reception intensity is not zero in any of the plurality of measurement conditions, and the difference between the maximum value and the minimum value of the measurement frequency in the plurality of measurement conditions is a predetermined value. When the value is below the threshold, the correction distribution is calculated by using the average value of the measurement frequencies in each of the plurality of measurement conditions as the correction measurement frequency for the reception intensity, and the correction reception is performed based on the calculated correction distribution. Since the intensity is calculated, the correction distribution is calculated by excluding the received intensity that is frequently measured only under specific measurement conditions from the corrected measurement frequency. Rukoto can, can be obtained as the reception intensity of the corrected reception strength with a reduced influence of radio interference based on the correction distribution.

  Another embodiment of the present invention will be further described. FIG. 14 is a functional block diagram for explaining a main part of the functions of the base station 12 in the present embodiment, corresponding to FIG. 3 in the above-described embodiment. In this embodiment, the base station 12 has at least one antenna 132, and has at least one radio unit 134, reception intensity detection unit 138, and distribution generation unit 140, which are provided corresponding to the antennas. This is different from the base station 12 of FIG. 3 described above. The operation of the measurement condition setting unit 146 is also different from that of the measurement condition setting unit 46 described above.

  An antenna 132 included in the base station 12 is used for transmitting and receiving radio waves by a wireless unit 134 described later, and is the same as the antenna 32 of the above-described embodiment.

  The radio unit 134 performs transmission / reception of radio waves in the base station 12 similarly to the radio unit 34 of the above-described embodiment, and is switched between a transmission state and a reception state by a control unit 136 described later. At the time of transmitting a radio wave, the radio unit 134 transmits the radio wave by the antenna 132 according to the control content instructed by the control unit 136, that is, the content of the signal wave, the frequency of the carrier wave, the transmission output, and the like. Thus, the wireless unit 134 includes a carrier wave generation circuit, a modulator, a transmission amplifier, and the like. In addition, the radio unit 134 amplifies the radio wave received by the antenna 132 when receiving the radio wave, and extracts a signal wave by performing predetermined demodulation processing or the like. That is, the wireless unit 134 includes a reception amplifier, a demodulator, and the like.

  Further, the radio unit 134 of the present embodiment can change the frequency (channel) of radio waves to be transmitted and received by a measurement condition setting unit 146 of the control unit 36 described later. That is, the carrier wave generation circuit, the demodulator, and the like included in the wireless unit 134 are adapted to a plurality of types of frequencies.

  The control unit 136 controls the operation of the base station 12. Specifically, the control unit 136 takes out information by the wireless unit 134, processes information obtained from the server 14 described later, and operates the base station 12 according to a command. Or change. The operation of the wireless unit 134, more specifically, control of transmission output and transmission frequency, generation of a signal wave transmitted wirelessly, and the like are performed. The control unit 136 is implemented by, for example, a known microcomputer. The wireless unit 134, the control unit 136, and the like have a function as a receiver.

  The control unit 136 has a measurement condition setting unit 146 functionally. The measurement condition setting unit 146 sets a plurality of measurement conditions when creating a distribution of measurement frequencies for the measurement value of the received intensity of the radio wave received by the distribution generation unit 140 described later. Similar to the above-described embodiment, the measurement frequency is, for example, the number of times of measurement at a predetermined measurement interval. Specifically, in this embodiment, the measurement condition setting unit 146 sets the plurality of measurement conditions as receiving at the base station 12 each of radio waves transmitted from the mobile station 10 at different frequencies. In other words, in the present embodiment, radio waves transmitted from the mobile station 10 using a plurality of types of frequencies are received by the radio unit 134 using the antenna 132, respectively. The operation of the measurement condition setting unit 146 corresponds to the measurement condition calculation process.

  Further, the measurement condition setting unit 146 may determine the radio waves having the plurality of types of frequencies as follows. First, each of the base station 10 and the mobile station 12 has a list of frequencies that can be transmitted and received with each other. Then, the base station 12 receives radio waves for each of the transmittable and transmittable frequencies, and predetermined wireless communication is performed around the base station 12 using the frequencies for a predetermined time. Detect whether or not. Then, the frequency at which the wireless communication is not performed for a predetermined time around the base station 12 for a predetermined time can be used for the wireless communication between the base station 12 and the mobile station 10. Suppose that the frequency of radio waves. Whether or not wireless communication is being performed is determined based on whether or not radio waves transmitted from other wireless stations are detected, for example. The fact that the wireless communication is not performed for the predetermined time corresponds to the fact that the index representing the radio wave interference satisfies a predetermined requirement. In this way, for each of the base stations 12, a list of radio wave frequencies that can be used for wireless communication between the base station 12 and the mobile station 10 is generated. Then, the measurement condition setting unit 146 sets the frequency of the radio wave that can be used for wireless communication with the mobile station 10 in common with all the base stations 12 as the plurality of types of frequencies.

  The reception intensity detection unit 138 measures the reception intensity of the radio wave received by each of the radio units 134. For example, the reception intensity detection unit 138 uses a clock signal supplied from a clock 48 described later in a predetermined reception time interval. Based on this, the value of the received intensity of the radio wave received at every predetermined measurement interval is detected. The reception intensity of the radio wave is represented by RSSI, for example, as in the above-described embodiment. Specifically, the reception intensity of the radio wave is represented by a predetermined number of 256 levels, for example. Further, the predetermined measurement interval is set, for example, so as to have a sufficient number of samples when the correction distribution is generated in the fluctuation removing unit 42. In addition, the detection of the reception intensity value by the reception intensity detection unit 138 is performed in a reception time interval that is a predetermined fixed time so that the same value is obtained under any measurement condition. This reception time interval is set to be the same as the transmission time, for example, corresponding to the length of the radio wave transmission time by the mobile station 10, for example. When the concept including the reception intensity detection unit 138 and the distribution generation unit 140 is a reception intensity measurement unit 52, the operation by the reception intensity measurement unit 52 corresponds to the reception intensity measurement process.

  The distribution generation unit 140 measures the radio waves measured when the reception intensity detection unit 138 receives each measurement condition, that is, each of a plurality of radio waves having different frequencies transmitted from the mobile station 10 in the reception time interval. A distribution of detection frequencies with respect to the received intensity value is generated for each of the plurality of frequencies.

  FIG. 15 is a flowchart for explaining an example of the control operation in the mobile station positioning system 8 of the present embodiment, which corresponds to FIG. 10 of the above-described embodiment. Among these, SE1 to SE5 correspond to SA1 to SA5 in FIG. 10 described above, and the same operations are performed, and thus description thereof is omitted.

  In SE6 corresponding to the radio unit 24 of the mobile station 10, radio waves for positioning are transmitted from the mobile station 10. Transmission of radio waves for this positioning is performed by a predetermined output. Transmission of radio waves in this step is performed so as to transmit radio waves of a plurality of types of frequencies determined as measurement conditions by the measurement condition setting unit 146, for example, according to a predetermined time pattern. Specifically, for example, the time pattern is a transmission of a radio wave of one of the plurality of types of frequencies for a predetermined transmission time, and the time pattern is different from the plurality of types of frequencies after a predetermined pause time has elapsed. The transmission and reception pause are repeated such that the transmission of the radio wave having the frequency of the predetermined frequency is performed for a predetermined transmission time, and this time pattern is also known in advance in the base station 12.

  In SE7 corresponding to the radio unit 134, the reception intensity detection unit 138, etc. of each base station 12, a radio wave for positioning transmitted from the mobile station 10 according to the time pattern in the above-described SE6 is received, The value is measured at, for example, a predetermined measurement interval. In SE6, the frequency of the radio wave transmitted from the mobile station 10 can be changed by the time pattern as described above. In response to this, specifically, the base station 12 also has the time pattern. The frequency of the radio wave received in this step is also changed. In this manner, a plurality of types of radio waves that are a plurality of measurement conditions are sequentially received. Further, as described above, for example, RSSI that evaluates the reception strength in 256 steps is used as the reception strength. Data measured in this way is obtained in time series order, that is, as a value of reception intensity with respect to reception time.

  In SE8 corresponding to the distribution generation unit 140, with respect to the reception intensity of radio waves of a plurality of frequencies received by the antenna 132 for each of a plurality of measurement conditions, the frequency distribution of the measurement frequency with respect to the value of the reception intensity for each frequency. (Histogram), for example, as shown in FIG. 7 (a) to (c).

  Subsequent SE9 to SE12 respectively correspond to SA9 to SA12 in the flowchart of FIG. 10 described above, and the operation in each step is the same, and thus the description thereof is omitted. For example, one of FIGS. 11 to 13 shown in the above-described embodiment is used for the fluctuation removal routine executed in SE9 corresponding to the fluctuation removal unit 42.

  According to the above-described embodiment, the measurement condition setting unit 146 sets the plurality of measurement conditions as receiving radio waves of a plurality of types of frequencies. Therefore, radio waves of a plurality of frequencies transmitted at different frequencies. Thus, the corrected received intensity calculated by a predetermined calculation method based on each of the received intensity can be obtained as the received intensity with reduced influence of radio wave interference.

  Further, according to the above-described embodiment, the mobile station positioning system 8 performs radio communication with another radio station at a predetermined time by using radio waves in communication between the base station 12 and the mobile station 10. A positioning condition setting unit 146 that sets, as the measurement condition, reception of a radio wave having a frequency that is not defined, that is, an index that represents radio wave interference satisfying a predetermined requirement. The frequency for transmitting and receiving radio waves between the mobile station 10 and the base station 12 can be set as the measurement condition, and can be obtained as reception intensity with reduced influence of radio wave interference.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the mobile station 10 moves on a plane. However, the mobile station 10 is not limited to this mode, and may move in space (three dimensions). In this case, an expression corresponding to the expression (1) may be derived by using the coordinates (x, y, z) representing the position of the mobile station 10 as unknowns.

  Further, in the above-described embodiment, the reception intensity calculation unit 44 is based on the histogram calculated as the correction distribution by the fluctuation removal unit 42, and the intermediate value of the classification of the reception intensity that generated the most correction measurement frequency in the histogram. However, the present invention is not limited to such a mode. For example, although the average value of the correction distribution is calculated as the corrected reception intensity, the present invention is not limited to this mode. Specifically, for example, an average in the histogram calculated as the correction distribution by the fluctuation removing unit 42 may be calculated, and the average may be used as the corrected reception intensity.

  In the above-described embodiment, the reception intensity detected by the reception intensity detectors 38 and 138 is, for example, RSSI evaluated in 256 stages. However, the present invention is not limited to this, and RSSI is evaluated in more stages. It may be a thing, and may be evaluated at a low stage. In addition, an index other than RSSI, such as received power, may be detected.

  In the above-described embodiment, the reception intensity section in the histogram (distribution) generated by the distribution generation sections 40 and 140 and the correction distribution generated by the fluctuation removal section 42 is 32 sections. I can't. That is, the number of sections can be changed by arbitrarily setting the definition of the reception strength and the width of the section.

  In the above-described embodiment, the distribution creating unit 40, the fluctuation removing unit 42, and the corrected received intensity calculating unit 44 are functions that the base station 12 has, but the present invention is not limited thereto. For example, it is possible to use these functions as the function of the server 14. In this case, information about the value of the reception intensity at each measurement interval measured by the reception intensity detectors 38 and 138 is transmitted from each base station 12 to the server 14 for each of the plurality of measurement conditions. Processing may be performed in the server 14. Conversely, the positioning unit 68 is a function of the base station 14 in the above-described embodiment, but may be a function of any of the base stations 12. In this way, there is no need to provide a separate server 14.

  In the embodiment described above, the value of the reception intensity in the reception intensity detection units 38 and 138 may be an instantaneous value of the reception intensity of the radio wave received by the radio units 34 and 134, or may be a predetermined number of times. It may be an average value of instantaneous values detected only.

It is a figure explaining the outline | summary of the mobile station positioning system which is one Example of this invention. It is a figure explaining the principal part of the function which the mobile station which comprises the mobile station positioning system of FIG. 1 has. It is a figure explaining the principal part of the function which the base station which comprises the mobile station positioning system of FIG. 1 has. It is a figure explaining the principal part of the function which the server which comprises the mobile station positioning system of FIG. 1 has. It is a figure explaining the influence of the fluctuation | variation in the receiving intensity of the received electromagnetic wave. It is a figure explaining the example of distribution of the detection frequency with respect to receiving intensity in case a fluctuation | variation arises in the receiving intensity of the received electromagnetic wave. It is a figure explaining the example of the distribution corresponding to several measurement conditions detected in the distribution production | generation part in the base station of FIG. FIG. 5 is an example of information stored in a storage unit of the server in FIG. 4, illustrating a relationship between a propagation distance of radio waves from a mobile station and reception intensity of radio waves. It is a figure explaining the principle of the positioning operation | movement in the positioning part of the server of FIG. It is a flowchart explaining the outline | summary of an example of an action | operation of the mobile station positioning system of FIG. It is a figure explaining an example of the fluctuation | variation removal routine performed in the flowchart of FIG. FIG. 11 is a diagram for explaining another example of a fluctuation removal routine executed in the flowchart of FIG. 10, corresponding to FIG. 10. FIG. 11 is a diagram for explaining still another example of the fluctuation removal routine executed in the flowchart of FIG. 10 and corresponding to FIG. 10. It is a figure explaining the principal part of the function which the base station in another Example of this invention has, Comprising: It is a figure corresponding to FIG. It is a flowchart explaining the outline | summary of the action | operation of the mobile station positioning system in another Example of this invention.

Explanation of symbols

8: Positioning system 10: Mobile station (transmitter)
12: Base station (receiver)
68: Positioning unit 46: Measurement condition setting unit (measurement condition setting step)
38, 138: Received intensity detector (received intensity measuring step)
40, 140: Distribution generator (reception intensity measurement process)
42: Fluctuation removal unit (reception intensity calculation step)
44: Corrected received power calculation unit (reception intensity calculation process)

Claims (9)

A reception strength measurement method for measuring the reception strength of a received radio wave,
A measurement condition setting step for setting a plurality of measurement conditions for receiving the radio waves to be received with different influences of interference in propagation of the radio waves;
For each of a plurality of measurement conditions set by the measurement condition setting step, the value of the reception intensity of the radio wave is measured at a predetermined measurement interval in a predetermined reception time interval, and the reception intensity is set to the interval. Dividing, a reception intensity measurement step of calculating a distribution of measurement frequency for each of the sections;
From the distribution of the measurement frequency with respect to the value of the reception intensity for each of the plurality of measurement conditions calculated by the reception intensity measurement step, the corrected measurement frequency in which the influence of the fluctuation of the reception intensity of the received radio wave is reduced is the reception intensity. By calculating the correction distribution by calculating the correction reception intensity of the received radio wave using the average of the correction measurement frequencies in the correction distribution or the highest correction measurement frequency. Intensity calculation process;
A reception intensity measuring method comprising: The reception intensity calculation step receives the measurement frequency with the smallest measurement frequency at the same reception intensity among the distributions calculated by the reception intensity measurement step for each of the measurement conditions set by the measurement condition setting step. The reception intensity measurement method according to claim 1, wherein the correction distribution is calculated by using the correction measurement frequency for the intensity, and the correction reception intensity is calculated based on the calculated correction distribution. The measurement condition setting step is to set the plurality of measurement conditions as receiving radio waves using each of a plurality of antennas provided at different positions;
The reception intensity measuring method according to claim 1. The measurement condition setting step is to set the plurality of measurement conditions as receiving radio waves of a plurality of types of frequencies,
The reception intensity measuring method according to claim 1. In the reception intensity calculation step, in the distribution calculated by the reception intensity measurement step for each of the measurement conditions set by the measurement condition setting step, a value obtained by multiplying the measurement frequency at the same reception intensity is received. The reception intensity measurement method according to claim 1, wherein the correction distribution is calculated by using the correction measurement frequency for the intensity, and the correction reception intensity is calculated based on the calculated correction distribution. In the reception intensity calculation step, in the distribution calculated by the reception intensity measurement step for each of the measurement conditions set by the measurement condition setting step, the measurement frequency at the same reception intensity is zero in any of the measurement conditions. In addition, when the difference between the maximum value and the minimum value of the measurement frequency under the plurality of measurement conditions is less than a predetermined threshold value, the average value of the measurement frequencies under each of the plurality of measurement conditions is corrected for the reception intensity. On the other hand, when the measurement frequency at the same reception intensity is zero in any of the measurement conditions, or the difference between the maximum value and the minimum value of the measurement frequency in the plurality of measurement conditions is equal to or greater than a predetermined threshold Tomo When calculates the corrected distribution by assuming no corrective measurement frequency in each of the plurality of measurement conditions , Reception intensity measuring method according to claim 1, characterized in that to calculate the corrected reception intensity based on the calculated the corrected distribution. A receiver including a reception intensity measurement unit for measuring the reception intensity of a received radio wave,
The reception intensity measurement unit
A measurement condition setting means for setting a plurality of measurement conditions for receiving the radio waves to be received with different influences of interference in propagation of the radio waves;
For each of a plurality of measurement conditions set by the measurement condition setting means, the value of the reception intensity of the radio wave is measured at a predetermined measurement interval in a predetermined reception time interval, and the reception intensity is set in the interval. A reception intensity measuring means for calculating a distribution of measurement frequencies for each of the sections;
From the distribution of the measurement frequency with respect to the value of the reception intensity for each of the plurality of measurement conditions calculated by the reception intensity measurement means, the corrected measurement frequency in which the influence of the fluctuation of the reception intensity of the received radio wave is reduced is the reception intensity. By calculating the correction distribution by calculating the correction reception intensity of the received radio wave using the average of the correction measurement frequencies in the correction distribution or the highest correction measurement frequency. Intensity calculation means;
A receiver comprising: A mobile station positioning system that transmits and receives radio waves between a plurality of base stations located at known positions and a movable mobile station, and calculates the position of the mobile station based on a reception result in the transmission and reception There,
Either one of the plurality of base stations and the mobile station is a receiver according to claim 7, and the other is a transmitter that transmits radio waves to the receiver.
A positioning unit that calculates a distance between each of the plurality of base stations and the mobile station based on the corrected reception intensity measured by the reception intensity measuring unit, and calculates a position of the mobile station based on the distance; about,
A mobile station positioning system. A measurement condition setting for setting, as the measurement condition, receiving a radio wave having a frequency satisfying a predetermined requirement for an index representing radio wave interference in communication between the receiver and a transmitter that transmits radio waves to the receiver Having a part,
The mobile station positioning system according to claim 8.

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