JP6942999B2 - Wireless communication devices, methods and wireless communication systems - Google Patents

Description

The present invention relates to wireless communication devices, methods and wireless communication systems.

In recent years, wireless communication devices that calculate the distance to an object have been actively used. For example, a wireless communication device is introduced into a factory to identify the position of an article in the factory and is used for product management or optimization of a manufacturing line. In many cases, the wireless communication device transmits an electric signal to the distance measurement target, receives a return signal corresponding to the signal from the distance measurement target, and calculates the distance based on the time difference between transmission and reception.

Since the traveling speed of an electric signal (radio wave) is 300,000 km / sec, which is equal to the speed of light, the distance can be calculated more accurately by considering the temporal spread of the electric signal (width of the electric signal). It will be possible. For example, when the width of a certain electric signal on the time axis is 10 nanoseconds, the maximum distance calculation result is -1.5 m depending on which position of the electric signal is treated as the arrival timing of the electric signal. An error of about + 1.5 m occurs. Therefore, for example, it is effective to treat the position of the apex of the electric signal (peak position) as the arrival timing of the electric signal.

Regarding the detection of the peak position, Patent Document 1 describes a circuit for detecting the peak time of the pulsed light, which detects the timing when the intensity of the pulsed light exceeds the threshold value, and the timing when the intensity of the pulsed light falls below the threshold value. A device comprising a circuit to detect is disclosed. The device identifies the central time of the timing detected in each of the two circuits as the peak position of the pulsed light.

Further, Patent Document 2 discloses a device for detecting an impulse waveform radio wave for improving the detection efficiency of a low-intensity radio wave. The device includes a comparator that outputs whether or not the intensity of radio waves exceeds a threshold value.

Japanese Unexamined Patent Publication No. 8-193890 Japanese Unexamined Patent Publication No. 2014-220745

However, when the device to be distanced transmits an electric signal, the wireless communication device may receive the reflected wave (delayed wave) of the electric signal in addition to the direct wave of the electric signal. Since the apparatus described in Patent Document 1 and the apparatus described in Patent Document 2 are not designed in consideration of the existence of the delayed wave, there is a concern that the delayed wave may be erroneously detected as a direct wave.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved wireless communication device, method, and a method capable of distinguishing a direct wave from a delayed wave. The purpose is to provide a wireless communication system.

In order to solve the above problems, according to a certain viewpoint of the present invention, a receiving unit that receives a signal transmitted from another wireless communication device and a strength and a threshold value of the received signal output from the receiving unit are determined. A comparison unit for comparison at intervals and a specific unit for specifying information on a received signal having the highest number of detections exceeding the threshold value among a plurality of received signals are provided and transmitted from the other wireless communication device. A wireless communication device is provided in which the signal is a pulse signal and the predetermined interval is less than half the time width of the pulse signal. Further, according to a certain viewpoint of the present invention, a comparison unit that compares a receiving unit that receives a signal transmitted from another wireless communication device with a strength and a threshold value of the received signal output from the receiving unit at predetermined intervals. And, among a plurality of received signals, the information regarding the received signal having the highest number of detections, which exceeds the threshold value, is provided with a specific unit for specifying the information regarding the received signal having the highest number of detections. A wireless communication device is provided which is the central time information of the period when the signal strength exceeds the threshold value.

The signal transmitted from the other wireless communication device may be a pulse signal.

The predetermined interval may be less than 1/2 of the time width of the pulse signal.

Each of the plurality of received signals may be a received signal output from the receiving unit within a predetermined time frame.

The information regarding the received signal having the highest number of detections may be the time information at the center of the period during which the strength of the received signal exceeds the threshold value.

The wireless communication device further includes a transmission unit that transmits a signal, and the signal received by the reception unit is a response transmitted from the other wireless communication device in response to the signal transmitted from the transmission unit. The other wireless communication device is a signal, and the wireless communication device is based on the time difference between the timing at which the signal is transmitted from the transmission unit and the timing indicated by the time information of the received signal having the highest number of detections. A distance calculation unit for calculating the distance between the device and the wireless communication device may be further provided.

Further, in order to solve the above problems, according to another viewpoint of the present invention, it is possible to compare the strength and the threshold value of the received signal of the signal transmitted from another wireless communication device at a predetermined interval, and to perform a plurality of receptions. Among the signals, the signal transmitted from the other wireless communication device includes the identification of the information regarding the received signal having the highest number of detections in which the intensity exceeds the threshold value, and the signal transmitted from the other wireless communication device is a pulse signal and is the predetermined interval. Is less than half the time width of the pulse signal, a method performed by a computer is provided. Further, according to another aspect of the present invention, the strength of the received signal of the signal transmitted from another wireless communication device and the threshold value are compared at predetermined intervals, and the threshold value among the plurality of received signals is determined. The information about the received signal with the highest number of detections, including identifying the information about the received signal with the highest number of detections, is in the middle of the period when the strength of the received signal exceeds the threshold. Time information, a method performed by a computer, is provided.

Further, in order to solve the above problems, according to another viewpoint of the present invention, a first wireless communication device and a second wireless communication device that transmits a signal in response to a signal transmitted from the first wireless communication device. A wireless communication system including a wireless communication device, wherein the first wireless communication device includes a receiving unit that receives a signal transmitted from the second wireless communication device and a receiving unit that receives a signal output from the receiving unit. It includes a comparison unit that compares the signal strength and the threshold value at predetermined intervals, and a specific unit that specifies information about the received signal having the highest number of detection times when the intensity exceeds the threshold value among a plurality of received signals. Provided is a wireless communication system in which the signal transmitted from the second wireless communication device is a pulse signal, and the predetermined interval is less than 1/2 of the time width of the pulse signal. Further, according to another aspect of the present invention, a radio including a first wireless communication device and a second wireless communication device that transmits a signal in response to a signal transmitted from the first wireless communication device. In a communication system, the first wireless communication device determines a receiving unit that receives a signal transmitted from the second wireless communication device, and a strength and a threshold value of the received signal output from the receiving unit. The comparison part that compares at intervals and
Among a plurality of received signals, the information regarding the received signal having the highest number of detections exceeding the threshold value is provided with a specific unit for specifying the information regarding the received signal having the highest number of detections. A wireless communication system is provided which is the central time information of the period when the intensity exceeds the threshold value.

As described above, according to the present invention, it is possible to distinguish between a direct wave and a delayed wave.

It is a figure which shows the outline of the distance measuring system which concerns on one Embodiment of this invention. It is explanatory drawing which shows the specific example about the identification of a peak position. It is explanatory drawing which shows the specific example about the identification of a peak position. It is explanatory drawing which shows the direct wave and the delay wave. It is explanatory drawing which shows the structure of the base station by embodiment of this invention. Counter: It is explanatory drawing which shows the specific example of the count-up of n. It is a flowchart which shows the operation of a base station. It is explanatory drawing which shows the specific example of the data stored in the record table A. It is a flowchart which shows the flow of the update process of the storage table B. It is explanatory drawing which shows the specific specific example of a peak timing. It is explanatory drawing which shows the specific specific example of a peak timing. It is a block diagram which showed the hardware configuration of a base station.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

Further, in the present specification and the drawings, a plurality of components having substantially the same functional configuration may be distinguished by adding different alphabets after the same reference numerals. For example, a plurality of configurations having substantially the same functional configuration or logical significance are distinguished as necessary, such as base stations 100A and 100B. However, when it is not necessary to particularly distinguish each of the plurality of components having substantially the same functional configuration, only the same reference numerals are given to each of the plurality of components. For example, when it is not necessary to distinguish between base stations 100A and 100B, each base station is simply referred to as base station 100.

<1. Overview of ranging system>
One embodiment of the present invention relates to a ranging system. First, the outline of the distance measuring system according to the embodiment of the present invention will be described with reference to FIG.

(1-1. Configuration of distance measurement system)
FIG. 1 is a diagram showing an outline of a distance measuring system according to an embodiment of the present invention. As shown in FIG. 1, the distance measuring system according to the embodiment of the present invention includes one or more base stations 100 and one or more mobile stations 200. The position of the mobile station 200 can be specified by calculating the distance between the three or more base stations 100 according to the present embodiment and the mobile station 200. That is, by utilizing the distance measuring system according to the present embodiment, positioning of the mobile station 200 becomes possible.

The ranging system according to this embodiment is used, for example, for product management in a factory. More specifically, the mobile station 200 is attached to the product manufactured in the factory, and the base station 100 specifies the position of the mobile station 200, so that the position of the product is specified, and the product management and the optimum of the production line are optimized. It becomes possible to visualize or long-term stagnant lots. In addition, the ranging system according to this embodiment is used for automating problem location records during inspections of social infrastructure such as tunnels and bridges, or for finding rescue-requiring persons and guiding personnel to evacuate when a disaster occurs in an underground facility or the like. Is also applicable.

The base station 100 is a wireless communication device (first wireless communication device) that transmits a signal to the mobile station 200 and receives a return signal corresponding to the signal. More specifically, the base station 100 transmits a pulse signal to the mobile station 200, and receives a pulse signal (return pulse signal) transmitted from the mobile station 200 in response to the pulse signal. Then, the base station 100 calculates the distance between the base station 100 and the mobile station 200 based on the time difference between the transmission timing of the pulse signal and the peak timing of the return pulse signal.

Here, as shown in FIG. 1, when a plurality of base stations 100 and a plurality of mobile stations 200 exist, one base station 100 may manage the transmission / reception schedule of the entire ranging system. For example, the base station 100A in FIG. 1 transmits in advance to each device a transmission / reception schedule that identifies each of the base station 100 and the mobile station 200 that transmit / receive pulse signals in each time zone. May be good. Thereby, in each time zone, the base station 100 that transmits and receives the pulse signal and the mobile station 200 that measures the distance are specified.

Alternatively, the base station 100 may transmit a signal designating the mobile station 200 prior to transmitting the pulse signal. For example, the base station 100 may transmit a pattern signal corresponding to one mobile station 200 prior to transmitting the pulse signal. The mobile station 200 can determine whether or not it has been designated based on the pattern signal received prior to the pulse signal, and can transmit the return pulse signal when it is designated.

The transmission and reception of the pulse signal may be performed according to, for example, UWB (Ultra Wide Band) using 7.25 GHz to 1.25 GHz. The UWB wideband signal is suitable for expressing the pulse shape of the pulse signal. On the other hand, the transmission / reception schedule or the notification of the pattern signal corresponding to each mobile station to each mobile station 200 may be performed according to a communication method (for example, wireless LAN) different from that of UWB.

The mobile station 200 is a wireless communication device (second wireless communication device) that receives the pulse transmitted by the base station 100 and transmits the return pulse to the base station 100.

(1-2. Background)
Here, in order to clarify the technical significance of the present invention, the background of the embodiments of the present invention will be described prior to the detailed description of the embodiments of the present invention.

Since the traveling speed of the pulse signal (radio wave) is 300,000 km / sec, which is equal to the speed of light, the distance can be calculated more accurately by considering the temporal spread of the pulse signal (width of the pulse signal). It will be possible. For example, when the width of a certain pulse signal on the time axis is 10 nanoseconds, the maximum distance calculation result is -1.5 m depending on which position of the pulse signal is treated as the arrival timing of the pulse signal. An error of about + 1.5 m occurs. Therefore, for example, it is effective to treat the position of the apex of the pulse signal (peak position) as the arrival timing of the pulse signal.

This peak position can be specified by AD-converting the received signal of the pulse signal and obtaining the signal strength at each time point. However, in order to specify the peak position by AD conversion, it is necessary to perform AD conversion at a time interval sufficiently shorter than the width of the pulse signal. Since such a high-speed AD conversion involves a corresponding processing load, other methods for identifying the peak position are also being studied. As another method, for example, a method of treating the timing when the signal strength of the received signal exceeds the threshold value as the peak position can be considered. The method will be described with reference to FIGS. 2 and 3.

2 and 3 are explanatory views showing a specific example regarding the identification of the peak position. As shown in FIG. 2, the smaller the signal strength of the received signal, the smaller the error between the peak position of the received signal and the timing when the signal strength of the received signal exceeds the threshold value. On the other hand, the greater the signal strength of the received signal, that is, the larger the difference between the signal strength of the received signal and the threshold value, the greater the timing error between the peak position of the received signal and the signal strength of the received signal exceeding the threshold value. Will grow.

Therefore, as shown in FIG. 3, if the threshold value is set higher than that in the example shown in FIG. 2, the error between the peak position of the received signal and the timing when the signal strength of the received signal exceeds the threshold value becomes small. .. However, the received signal whose signal strength does not reach the high threshold value will not be detected.

Regarding this point, Patent Document 1 describes a device for measuring the peak time of pulsed light, a circuit for detecting the timing when the intensity of the pulsed light exceeds the threshold value, and the timing when the intensity of the pulsed light falls below the threshold value. A device comprising a circuit is disclosed. The device identifies the central time of the timing detected in each of the two circuits as the peak position of the pulsed light. Further, Patent Document 2 discloses a device for detecting an impulse waveform radio wave for improving the detection efficiency of a low-intensity radio wave. The device includes a comparator that outputs whether or not the intensity of radio waves exceeds a threshold value.

However, when the device to be distanced transmits an electric signal, the wireless communication device may receive the reflected wave (delayed wave) of the electric signal in addition to the direct wave of the electric signal as shown in FIG. .. Since the apparatus described in Patent Document 1 and the apparatus described in Patent Document 2 are not designed in consideration of the existence of the delayed wave, there is a concern that the delayed wave may be erroneously detected as a direct wave.

Further, in the apparatus described in Patent Document 1, two circuits are provided, one is a circuit for detecting the timing when the intensity of the pulsed light exceeds the threshold value and the other is a circuit for detecting the timing when the intensity of the pulsed light is below the threshold value. The configuration becomes complicated. Further, in the apparatus described in Patent Document 2, a position deviated from the actual peak position may be specified due to the processing delay required for forming the radio wave by the discharger and the setting of the threshold value.

The present inventor has come to create an embodiment of the present invention with the above circumstances as the first point of view. According to the embodiment of the present invention, it is possible to specify the peak position of the received signal with higher accuracy while distinguishing between the delayed wave and the direct wave. Hereinafter, the configuration and operation of such an embodiment of the present invention will be sequentially described in detail.

<2. Base station configuration>
FIG. 5 is an explanatory diagram showing the configuration of the base station 100 according to the embodiment of the present invention. As shown in FIG. 5, the base station 100 according to the embodiment of the present invention includes a signal processing unit 104, a transmitting amplifier circuit 108, an antenna 112, a bandpass filter 116, a receiving amplifier circuit 120, and a signal processing unit. It includes 124, a comparator 128, a control unit 130, a clock IC 140, and a memory IC 150.

The signal processing unit 104 up-converts the baseband transmission signal input from the control unit 130 into a radio frequency band transmission signal. The transmission amplifier circuit 108 amplifies the transmission signal of the radio frequency band input from the signal processing unit 104, and applies the amplified transmission signal to the antenna 112. The antenna 112 transmits a transmission signal applied by the signal processing unit 104.

Further, the antenna 112 functions as a receiving unit for receiving the signal transmitted from the mobile station 200 in cooperation with the bandpass filter 116, the receiving amplifier circuit 120, and the signal processing unit 124. Specifically, the antenna 112 outputs a signal induced based on the signal transmitted from the mobile station 200, and the bandpass filter 116 passes a component of the radio frequency band of the signal output from the antenna 112. .. The receiving amplifier circuit 120 amplifies the signal input from the bandpass filter 116, and the signal processing unit 124 converts the signal input from the receiving amplifier circuit 120 into a baseband receiving signal, and converts the baseband receiving signal into a baseband receiving signal. Output.

The comparator 128 is a comparison unit that compares the signal strength (voltage) of the received signal output from the signal processing unit 124 with the threshold value at predetermined intervals. For example, the comparator 128 may output "1" when the signal strength of the received signal exceeds the threshold value, and may output "0" when the signal strength of the received signal is equal to or less than the threshold value.

The clock IC 140 has, for example, a crystal and generates a clock signal. The memory IC 150 is a readable and writable memory such as an SDRAM (Synchronous Dynamic Random Access Memory). In the present embodiment, the memory IC 150 stores a counter: n, a flag, a recording table A, and a storage table B, which will be described later.

The control unit 130 controls the overall operation of the base station 100. For example, the control unit 130 controls the reception processing by the bandpass filter 116, the reception amplifier circuit 120, the signal processing unit 124, and the like, and controls the transmission processing by the signal processing unit 104, the transmission amplifier circuit 108, and the like. Such a control unit 130 may be a programmable IC such as an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), or a CPU (Central Processing Unit).

Further, as shown in FIG. 5, the control unit 130 according to the present embodiment has the functions of the threshold value setting unit 132, the time management unit 134, the memory management unit 136, and the distance calculation unit 138.

(Threshold setting unit)
The threshold value setting unit 132 sets a threshold value to be compared with the signal strength of the received signal by the comparator 128.

(Time management department)
The time management unit 134 has a function of controlling the clock IC 140, and manages the current time based on the clock signal generated by the clock IC 140.

(Memory management department)
The memory management unit 136 has a function as a specific unit that distinguishes a plurality of received signals into a direct wave or a delayed wave and specifies information about the direct wave (for example, the peak timing of the direct wave). In order to realize the function as the specific unit, the memory management unit 136 manages the counters: n, flags, recording table A and storage table B stored in the memory IC 150 based on the comparison result input from the comparator 128. do.

Counter: n is the number of times that the comparator 128 continuously determines that the signal strength of the received signal exceeds the threshold value, that is, the number of times the received signal is detected. The memory management unit 136 counts up the counter: n each time a comparison result indicating that the signal strength of the received signal exceeds the threshold value is continuously input from the comparator 128. Then, the memory management unit 136 resets the counter: n to 0 when the signal strength of the received signal becomes equal to or less than the threshold value. Here, with reference to FIG. 6, the count-up of the counter: n will be specifically described.

FIG. 6 is an explanatory diagram showing a specific example of counting up the counter: n. In FIG. 6, the received signal 1 to the received signal 4 are shown, and the vertical line indicates the timing at which the comparison by the comparator 128 is performed.

As shown in FIG. 6, when the signal strength of the received signal 1 exceeds the threshold value in the five comparisons by the comparator 128, the memory management unit 136 counts up the counter: n for the received signal 1 to “5”. .. Then, when the comparison result indicating that the signal strength of the received signal 1 is below the threshold value is input from the comparator 128, the memory management unit 136 resets the counter: n. Similarly, when the signal strength of the received signal 2 exceeds the threshold value in the three comparisons by the comparator 128, the memory management unit 136 counts up the counter: n for the received signal 2 to "3". On the other hand, with respect to the received signal 4, since the signal strength of the received signal 4 has not reached the threshold value, the counter: n is not counted up.

The time interval in which the comparator 128 compares the signal strength of the received signal with the threshold value is less than 1/2 of the time width of the pulse signal so that the signal strength of the received signal of the pulse signal can exceed the threshold value multiple times. It may be.

The flag indicates whether or not the counter: n is being counted up by the memory management unit 136. For example, the memory management unit 136 may set the flag to "1" when the counter: n continues to count up, and set the flag to "0" when the counter: n is reset. good.

The record table A is data in which each count value of the counter: n and the time when the count-up to each count value is performed are associated with each other. The memory management unit 136 stores the value of the counter: n after the count-up in the recording table A in association with the current time each time the counter: n is counted up. That is, the memory management unit 136 stores the detection number of the received signal (counter: each count value of n) and the detection time of the received signal (time when the count-up is performed) in the recording table A. The record table A is initialized together with the reset of the counter: n.

The recording table B shows data associated with the peak timing of the received signal in which the counter: n is counted up to the largest value within a predetermined time frame, and the final detection number which is the final value of the counter: n of the received signal. Is. When the final detection number of the new received signal exceeds the final detection number stored in the recording table B, the memory management unit 136 determines the peak timing of the new received signal and the final detection number of the new received signal. Overwrite the data in the record table B. The peak timing of the received signal is specified based on the detection time of the received signal stored in the recording table A in association with the detection number of the received signal, as will be described later with reference to FIGS. 9 to 11.

Here, it is assumed that the signal strength of the direct wave is stronger than the signal strength of the delayed wave, and the final detection number of the direct wave is larger than the final detection number of the delayed wave. Therefore, when the direct wave and the delayed wave are mixed and reach the base station 100 in the predetermined time frame, the peak timing and the final number of detections stored in the recording table B at the time when the predetermined time frame elapses are directly obtained. It is expected to be the peak timing of the wave and the final number of detections of the direct wave. Therefore, the memory management unit 136 specifies the peak timing stored in the recording table B as the peak timing of the direct wave when the predetermined time frame has elapsed.

The predetermined time frame may be a time frame in which it is expected that the return pulse signal will be received from the mobile station 200. Specifically, the predetermined time frame may be a time frame between the transmission timing at which the base station 100 transmits the pulse signal to the mobile station 200 and the timing after a predetermined time from the transmission timing. In such a time frame, the direct wave and the delayed wave may coexist as described above, but the function of the memory management unit 136 described above distinguishes the direct wave from the delayed wave and specifies the peak timing of the direct wave. Is possible.

(Distance calculation unit)
The distance calculation unit 138 is based on the time difference between the transmission timing at which the base station 100 transmits the pulse signal and the peak timing of the direct wave of the return pulse signal specified by the memory management unit 136, and the base station 100 and the mobile station 200 Calculate the distance between and. For example, the distance calculation unit 138 may calculate the distance D between the base station 100 and the mobile station 200 according to the following mathematical formula.
D = c (Tr-Tt-Tw) / 2

In the above formula, c indicates the speed of light, Tr indicates the peak timing of the direct wave of the return pulse signal, Tt indicates the transmission timing of the pulse signal, and Tw indicates the standby time in the mobile station 200. The standby time is the time from when the mobile station 200 receives the pulse signal to when the return pulse signal is transmitted. It is assumed that the mobile station 200 and the base station 100 store a predetermined value of the standby time in the mobile station 200 in advance. Since the reflected wave of the pulse signal transmitted by the base station 100 is settled during the elapse of the standby time, the reflected wave of the pulse signal transmitted by the base station 100 and the return wave transmitted by the mobile station 200 are returned by the standby of the standby time. It is possible to prevent the direct wave or the delayed wave of the pulse signal from reaching the base station 100 at the same time. As a result, it is possible to improve the accuracy of distance calculation in the base station 100.

<3. Base station operation>
The configuration of the base station 100 according to the embodiment of the present invention has been described above. Subsequently, the operation of the base station 100 according to the embodiment of the present invention will be described.

FIG. 7 is a flowchart showing the operation of the base station 100. As shown in FIG. 7, when the pulse signal is transmitted from the base station 100, the memory management unit 136 performs the initialization process of the memory IC 150 (S304). Specifically, the memory management unit 136 sets the counter: n to "0", sets the flag to "0", and creates the recording table A and the storage table B.

Then, the threshold value setting unit 132 sets the threshold value to be compared with the signal strength of the received signal by the comparator 128 (S308). After that, the processes of S316 to S360 are repeated until a predetermined time frame elapses (S312 / no).

Specifically, the memory management unit 136 determines when the output from the comparator 128 is "1", that is, when the comparator 128 determines that the signal strength of the received signal exceeds the threshold value (S316 / yes). , The flag is set to "1" (S320), and the counter: n is counted up (S324).

Then, the time management unit 134 reads the current time from the clock IC 140 (S328), and the memory management unit 136 uses the value of the counter: n as the detection number of the received signal and the current time read in S328 as the received signal. It is stored in the record table A as the detection time (S332). After that, the process from S312 is repeated. Here, a specific example of the data stored in the recording table A will be described with reference to FIG.

FIG. 8 is an explanatory diagram showing a specific example of the data stored in the recording table A. While the processes of S312 to S332 described above are repeated, the detection number of the received signal and the detection time of the received signal are sequentially added to the recording table A as shown in FIG.

On the other hand, when the output of the comparator is "0" (S316 / no), the memory management unit 136 confirms whether or not the flag is "1" (S336). When the flag is "1", that is, when the received signal that has been detected up to the latest is no longer detected (S336 / yes), the process proceeds to S340 or later. On the other hand, when the flag is "0", that is, when the period during which the received signal is not detected is continuing (S336 / no), the processing from S312 is repeated.

In S340, the memory management unit 136 determines whether or not the counter: n is equal to or greater than the final number of detections stored in the storage table B (S340). Counter: When n is equal to or greater than the final number of detections stored in the storage table B (S340 / yes), the memory management unit 136 sets the flag to "0" after executing the update processing of the storage table B (S350). Then, the counter: n is reset to "0", and the recording table A is initialized (S360). When the counter: n is less than the final number of detections stored in the storage table B (S340 / no), the memory management unit 136 executes the process of S360 without going through the update process of the storage table B. Here, the update process (S350) of the storage table B is a process of storing the time at the center of the period in which the received signal is detected in the storage table B as the peak timing of the received signal. Hereinafter, the update process of the storage table B will be specifically described with reference to FIG.

FIG. 9 is a flowchart showing the flow of the update process of the storage table B. As shown in FIG. 9, when the counter: n is an odd number (S352 / yes), the memory management unit 136 displays the detection time T _{(n + 1) / corresponding to the detection number (n + 1) / 2 from the recording table A. 2} is selected (S354). Then, the memory management unit 136 _{stores (overwrites) the detection time T (n + 1) / 2} as the peak timing T and the value of the counter: n as the final detection number in the storage table B (S356).

For example, as shown in FIG. 10, when the received signal is detected five times over the detection times T1 to T5, the value of the counter: n in S352 becomes "5". In this case, as shown in the lower part of FIG. 8, the memory management unit 136 stores the detection time T3 corresponding to the detection number 3 (= (n + 1) / 2) in the storage table B as the peak timing T of the received signal. do. Further, the memory management unit 136 stores the value “5” of the counter: n as the final detection number in the storage table B.

On the other hand, when the counter: n is an even number (S352 / no), the memory management unit 136 displays the detection time T _{n / 2} and the detection number (n / 2) corresponding to the detection number n / 2 from the recording table A. The detection time T _{(n / 2) +1} corresponding to +1 is selected, and (T _{n / 2} + T _{(n / 2) +1} ) / 2 is calculated (S358). The memory management unit 136 stores (overwrites) the calculation result in S358 as the peak timing T and the value of the counter: n as the final detection number in the storage table B (S356).

For example, as shown in FIG. 11, when the received signal is detected four times over the detection times T1 to T4, the value of the counter: n in S352 becomes "4". In this case, the memory management unit 136 selects the detection time T2 corresponding to the detection number 2 (= n / 2) and the detection time T3 corresponding to the detection number 3 (= (n / 2) + 1), and (T2 + T3). ) / 2 is calculated. The memory management unit 136 stores the result of the calculation in the storage table B as the peak timing T of the received signal. Further, the memory management unit 136 stores the value “4” of the counter: n as the final detection number in the storage table B.

Here, with reference to FIG. 7, the description of the operation of the base station 100 is returned. When it is determined in S312 that the predetermined time frame has elapsed through the processes of S312 to S360 described above (S312 / yes), the memory management unit 136 returns the peak timing T stored in the storage table B. It is specified as the peak timing T of the direct wave of the pulse signal (S364).

After that, the distance calculation unit 138 sets the base station 100 and the mobile station 200 based on the time difference between the transmission timing at which the base station 100 transmits the pulse signal and the peak timing T of the direct wave of the return pulse signal specified in S364. The distance between them is calculated (S368).

<4. Hardware configuration>
The embodiments of the present invention have been described above. Information processing such as memory management and distance calculation described above is realized by the cooperation between the software and the hardware of the base station 100 described below.

FIG. 12 is a block diagram showing a hardware configuration of the base station 100. As shown in FIG. 12, the base station 100 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, and a host bus 204. Further, the base station 100 includes a bridge 205, an external bus 206, an interface 207, an input device 208, a display device 209, an audio output device 210, a storage device (HDD) 211, a drive 212, and a network interface. It includes 215 and a comparator 128.

The CPU 201 functions as an arithmetic processing device and a control device, and controls the overall operation in the base station 100 according to various programs. Further, the CPU 201 may be a microprocessor. The ROM 202 stores programs, calculation parameters, and the like used by the CPU 201. The RAM 203 temporarily stores a program used in the execution of the CPU 201, parameters that change appropriately in the execution, and the like. These are connected to each other by a host bus 204 composed of a CPU bus or the like. The CPU 201, ROM 202, and RAM 203 can realize the functions of the control unit 130 described above in cooperation with software.

The host bus 204 is connected to an external bus 206 such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge 205. It is not always necessary to separately configure the host bus 204, the bridge 205, and the external bus 206, and these functions may be implemented in one bus.

The input device 208 includes input means for the user to input information such as a mouse, a keyboard, a touch panel, a button, a microphone, a sensor, a switch, and a lever, and an input that generates an input signal based on the input by the user and outputs the input signal to the CPU 201. It is composed of a control circuit and the like. By operating the input device 208, the user of the base station 100 can input various data to the base station 100 and instruct the processing operation.

The display device 209 includes, for example, a display device such as a CRT (Cathode Ray Tube) display device, a liquid crystal display (LCD) device, a projector device, an OLED (Organic Light Emitting Mode) device, and a lamp. Further, the audio output device 210 includes an audio output device such as a speaker and headphones.

The storage device 211 is a data storage device configured as an example of the storage unit of the base station 100 according to the present embodiment. The storage device 211 may include a storage medium, a recording device that records data on the storage medium, a reading device that reads data from the storage medium, a deleting device that deletes the data recorded on the storage medium, and the like. The storage device 211 is composed of, for example, an HDD (Hard Disk Drive) or an SSD (Solid Stage Drive). The storage device 211 drives a hard disk and stores programs and various data executed by the CPU 201.

The drive 212 is a storage medium reader / writer, and is built in or externally attached to the base station 100. The drive 212 reads the information recorded in the removable storage medium 24 such as the mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs the information to the RAM 203 or the storage device 211. The drive 212 can also write information to the removable storage medium 24.

The network interface 215 is, for example, a communication interface composed of a communication device or the like for communicating with the mobile station 200. The network interface 215 may include a UWB communication device and a wireless LAN communication device. As described with reference to FIG. 5, the comparator 128 is a dedicated IC that compares the signal strength of the received signal output from the network interface 215 with the threshold value. The functions of the signal processing unit 104, the transmitting amplifier circuit 108, the antenna 112, the bandpass filter 116, the receiving amplifier circuit 120, and the signal processing unit 124 described with reference to FIG. 5 may be included in the network interface 215.

Since the hardware configuration of the base station 100 described above can be applied to the hardware configuration of the mobile station 200, a detailed description of the hardware configuration of the mobile station 200 will be omitted.

<5. Conclusion>
As described above, according to the embodiment of the present invention, for a plurality of received signals obtained in a predetermined time frame, the number of times the signal strength exceeds the threshold value (the number of detections) in comparison at a predetermined interval is counted. .. It is assumed that the signal strength of the direct wave is stronger than the signal strength of the delayed wave, and the final detection number of the direct wave is larger than the final detection number of the delayed wave. Therefore, among the plurality of received signals obtained in a predetermined time frame, the received signal having the largest number of final detections can be specified as the received signal of the direct wave.

When the return pulse signal is transmitted from the mobile station 200, of the direct wave and the delay wave of the return pulse signal, the direct wave of the return pulse signal first reaches the base station 100, so that it is simply received first. A method of treating the signal as a direct wave is also conceivable. However, since the reflected wave of the pulse signal transmitted by the base station 100 may remain, the method erroneously detects the reflected wave of the pulse signal transmitted by the base station 100 as a direct wave of the folded pulse signal. There is a risk that it will end up. On the other hand, according to the embodiment of the present invention, it is assumed that the final detection number of the direct wave of the folded pulse signal is larger than the final detection number of the reflected wave of the pulse signal transmitted by the base station 100. Therefore, it is possible to correctly identify the direct wave of the folded pulse signal.

Further, regarding the method of measuring the signal strength of the received signal by AD conversion, the signal strength is divided between the processing load in which the signal strength and the threshold value are compared at a certain time interval and the processing load in which the signal strength is AD-converted at the time interval. The processing load for AD conversion is larger. In addition, the amount of data showing the result of AD conversion of signal strength is overwhelmingly larger than the amount of data showing the result of AD conversion of signal strength between the amount of data showing the result of comparison between the signal strength and the threshold. It is large and consumes a huge amount of memory. Therefore, the embodiment of the present invention can reduce the processing load and the required memory capacity as compared with the method of measuring the signal strength of the received signal by AD conversion.

Further, according to the present embodiment, it is possible to specify the central value of the period during which the reception signal of the direct wave is detected as the peak timing of the direct wave. By appropriately specifying the peak timing of the direct wave in this way, the distance between the base station 100 and the mobile station 200 can be calculated more accurately.

Although preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

For example, each step in the processing of the base station 100 of the present specification does not necessarily have to be processed in chronological order in the order described as a flowchart. For example, each step in the processing of the base station 100 may be processed in an order different from the order described in the flowchart, or may be processed in parallel.

Further, it is possible to create a computer program for causing the hardware such as the CPU 201, ROM 202, and RAM 203 built in the base station 100 to exhibit the same functions as each configuration of the base station 100 described above. A storage medium for storing the computer program is also provided.

100 Base station 104 Signal processing unit 108 Transmission amplifier circuit 112 Antenna 116 Bandpass filter 120 Reception amplifier circuit 124 Signal processing unit 128 Comparator 130 Control unit 132 Threshold setting unit 134 Time management unit 136 Memory management unit 138 Distance calculation unit 200 Mobile station

Claims (11)

A receiver that receives signals transmitted from other wireless communication devices,
A comparison unit that compares the strength and threshold value of the received signal output from the reception unit at predetermined intervals, and
Among a plurality of received signals, a specific unit that specifies information related to the received signal having the highest number of detections in which the intensity exceeds the threshold value, and
With
The signal transmitted from the other wireless communication device is a pulse signal and is
A wireless communication device in which the predetermined interval is less than 1/2 of the time width of the pulse signal. A receiver that receives signals transmitted from other wireless communication devices,
A comparison unit that compares the strength and threshold value of the received signal output from the reception unit at predetermined intervals, and
Among a plurality of received signals, a specific unit that specifies information related to the received signal having the highest number of detections in which the intensity exceeds the threshold value, and
With
The information regarding the received signal having the highest number of detections is the time information at the center of the period during which the strength of the received signal exceeds the threshold value, that is, the wireless communication device. The wireless communication device according to claim 2 , wherein the signal transmitted from the other wireless communication device is a pulse signal. The wireless communication device according to claim 3 , wherein the predetermined interval is less than 1/2 of the time width of the pulse signal. The wireless communication device according to any one of claims 1 to 4 , wherein each of the plurality of received signals is a received signal output from the receiving unit within a predetermined time frame. The wireless communication device according to claim 1 , wherein the information regarding the received signal having the highest number of detections is the time information at the center of the period during which the strength of the received signal exceeds the threshold value. The wireless communication device further includes a transmitter for transmitting a signal.
The signal received by the receiving unit is a response signal transmitted from the other wireless communication device in response to the signal transmitted from the transmitting unit.
The wireless communication device communicates with the other wireless communication device based on the time difference between the timing at which the signal is transmitted from the transmission unit and the timing indicated by the time information of the received signal having the highest number of detections. The wireless communication device according to claim 6 , further comprising a distance calculation unit for calculating the distance to and from the communication device. Comparing the strength of the received signal of the signal transmitted from another wireless communication device and the threshold value at predetermined intervals, and
To identify the information regarding the received signal having the highest number of detections in which the intensity exceeds the threshold value among the plurality of received signals.
Including
The signal transmitted from the other wireless communication device is a pulse signal and is
A method performed by a computer , wherein the predetermined interval is less than half the time width of the pulse signal. Comparing the strength of the received signal of the signal transmitted from another wireless communication device and the threshold value at predetermined intervals, and
To identify the information regarding the received signal having the highest number of detections in which the intensity exceeds the threshold value among the plurality of received signals.
Including
The information about the received signal with the highest number of detections is the time information in the middle of the period when the strength of the received signal exceeds the threshold value, which is a method executed by a computer. A wireless communication system including a first wireless communication device and a second wireless communication device that transmits a signal in response to a signal transmitted from the first wireless communication device.
The first wireless communication device is
A receiving unit that receives a signal transmitted from the second wireless communication device, and
A comparison unit that compares the strength and threshold value of the received signal output from the reception unit at predetermined intervals, and
Among a plurality of received signals, a specific unit that specifies information related to the received signal having the highest number of detections in which the intensity exceeds the threshold value, and
With
The signal transmitted from the second wireless communication device is a pulse signal, and is
A wireless communication system in which the predetermined interval is less than 1/2 of the time width of the pulse signal. A wireless communication system including a first wireless communication device and a second wireless communication device that transmits a signal in response to a signal transmitted from the first wireless communication device.
The first wireless communication device is
A receiving unit that receives a signal transmitted from the second wireless communication device, and
A comparison unit that compares the strength and threshold value of the received signal output from the reception unit at predetermined intervals, and
Among a plurality of received signals, a specific unit that specifies information related to the received signal having the highest number of detections in which the intensity exceeds the threshold value, and
With
The information regarding the received signal having the highest number of detections is the time information at the center of the period during which the strength of the received signal exceeds the threshold value, which is a wireless communication system.

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