JP2006013894A - Communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system capable of accurately measuring a communication distance between two communication terminals. <P>SOLUTION: The communication system comprises a transmitter and a receiver located in a wireless communication space. The transmitter completes the transmission of data DATT to the receiver synchronously with a start edge (timing t1) of a free period in the wireless communication space. When the receiver completes the reception of data DARR from the transmitter, the receiver measures its own response time Tresp and starts the transmission of data DART including the response time Tresp to an oscillator when the receiver completes the measurement of the response time Tresp. The oscillator starts receiving the data DART from the receiver in a timing t4, measures the total time from timing t1 to timing t4, and determines the communication distance with the receiver on the basis of the measured total time and the response time Tresp received from the receiver. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication system, and more particularly to a communication system capable of measuring a communication distance between two communication terminals.

  In a conventional wireless LAN (Local Area Network) system, a CDMA (Code Division Multiple Access) method is used as a physical layer protocol, and a CSMA / CA (Carrier Sense) is used as a medium access control method in a data link layer. Multiple Access with Collation Avidance) is used.

  This CSMA / CA method is a method for avoiding a communication collision by constantly monitoring whether another communication terminal is transmitting a packet and whether a packet addressed to itself is being transmitted (non-transmission). Patent Document 1). That is, each communication terminal transmits data after confirming that the network is continuously available for a predetermined time or more.

Thus, in the conventional wireless LAN system, data communication is performed using the CSMA / CA method.
By Koizumi, “All of Data Communication with Illustrations”, Nihon Jitsugyo Publishing Co., Ltd., November 20, 1999, p. 272

  However, the conventional wireless LAN system has a problem that the communication distance between two communication terminals cannot be measured. In addition, when measuring the communication distance between two communication terminals by measuring the round-trip time during which data reciprocates between the two communication terminals, there is also a problem that it is difficult to accurately measure the communication distance.

  That is, when measuring the communication distance between two communication terminals by measuring the round-trip time during which the data travels back and forth between the two communication terminals, the communication terminal to measure the communication distance (that is, the communication distance is measured). The communication terminal) receives data from the communication terminal that measures the communication distance, and then transmits the data to the communication terminal that measures the communication distance after a predetermined time has elapsed. That is, the communication terminal whose communication distance is measured transmits the received data after a predetermined response time has elapsed. The response time of the communication terminal whose communication distance is measured varies depending on the model of the communication terminal. Therefore, the round trip time for data to and from the two communication terminals differs depending on the response time of the communication terminal whose communication distance is measured, and the round trip time for data to and from the wireless communication space cannot be determined accurately. As a result, it becomes difficult to accurately measure the communication distance.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to provide a communication system capable of accurately measuring a communication distance between two communication terminals.

  According to this invention, the communication system is a communication system capable of measuring a communication distance between two communication terminals arranged in a wireless communication space, and includes a transmitter and a receiver. The transmitter transmits data via the wireless communication space. The receiver receives data from the transmitter via the wireless communication space, and transmits data for a response to the received data to the transmitter via the wireless communication space. The transmitter and the receiver transmit and receive data in synchronization with the reference clock. The transmitter measures the total time between the first timing for completing the transmission of data to the receiver and the second timing for starting the reception of data from the receiver, and the measured total time. And the communication distance to the receiver is determined based on the response time of the receiver received from the receiver.

  Preferably, the receiver measures the response time according to the completion of reception of data from the transmitter, and transmits the response time to the transmitter after the measured response time has elapsed. The transmitter subtracts the received response time from the total time, calculates a round trip time for data to and from the receiver, and determines a communication distance to the receiver based on the calculated round trip time.

  Preferably, the transmitter transmits an instruction packet instructing measurement of response time to the receiver, receives a reply packet including the response time from the receiver, and acquires the response time. The receiver measures the response time according to the instruction packet, and transmits a reply packet including the response time to the transmitter after the measured response time has elapsed.

  Preferably, each time the data is received from the transmitter, the receiver measures the response time and stores a plurality of response times. When receiving an instruction packet instructing transmission of the response time from the transmitter, the receiver stores the plurality of stored times. A reply packet including the response time is transmitted to the transmitter. The transmitter transmits an instruction packet to the receiver at an arbitrary timing, receives a reply packet from the receiver, acquires a plurality of response times, and averages the average response times of the acquired response times. The communication distance to the receiver is determined by subtracting from.

  Preferably, the receiver measures a response time each time data is received from the transmitter, thereby using a plurality of vacant periods in the wireless communication space, and a plurality of responses corresponding to the plurality of data transmitted from the transmitter. When the time is measured, the first history information including the measured response times is stored in the first storage device, and the transmission request requesting the transmission of the response time is received from the transmitter, the first memory is stored. First history information is acquired from the device and transmitted to the transmitter. The transmitter measures the total time corresponding to the plurality of data by measuring the total time each time each data is transmitted to the receiver, and obtains the second history information including the measured total times. The second storage device stores the transmission request to the receiver, receives the first history information from the receiver, acquires a plurality of response times, and acquires the plurality of response times and the second Based on a plurality of total times included in the second history information acquired from the storage device, a plurality of communication distances corresponding to a plurality of data are determined.

  Preferably, the first history information includes a plurality of sequence numbers assigned to a plurality of data and a plurality of response times associated with the plurality of sequence numbers. The second history information includes a plurality of sequence numbers and a plurality of total times associated with the plurality of sequence numbers. When the transmitter receives the first history information from the receiver, the transmitter acquires the second history information from the second storage device, and based on the plurality of sequence numbers included in the acquired second history information. A plurality of communication distances corresponding to a plurality of data are determined by associating a plurality of total times with a plurality of response times.

  Preferably, the receiver receives a transmission request from the transmitter according to a protocol for specifying a communication partner among a plurality of protocols used for communication with the transmitter, and transmits first history information to the transmitter. The transmitter transmits a transmission request to the receiver according to a protocol for specifying a communication partner and receives first history information from the receiver.

  Preferably, the second timing is a timing at which the transmitter starts to stably receive data from the receiver. Then, the transmitter determines the communication distance based on a certain time including the response time and the total time.

  Preferably, the second timing is a start frame delimiter.

  In the communication system according to the present invention, the communication distance between the transmitter and the receiver is determined by measuring the idle period of the wireless communication space in which the data propagates between the transmitter and the receiver. The The propagation time is measured from the total time between the first timing at which the transmitter finishes transmitting data to the receiver and the second timing at which the transmitter starts receiving data from the receiver. This is done by subtracting the response time of the receiver, and the response time of the receiver is transmitted from the receiver to the transmitter.

  Therefore, according to the present invention, even when the response time of the receiver changes variously, it is possible to accurately determine the round-trip time for data to reciprocate in the wireless communication space. As a result, it is possible to accurately determine the communication distance between the transmitter and the receiver using the free period of the wireless communication space.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a schematic block diagram of a communication system according to Embodiment 1 of the present invention. The communication system 100 includes wireless devices 10, 30, 40, and 50. The wireless devices 10, 30, 40, 50 are arranged in the wireless communication space 20, and perform data communication with each other by the CSMA / CA method.

  In the following description, it is assumed that the wireless device 10 is a measuring device that measures a communication distance with the wireless devices 30, 40, and 50, and the wireless devices 30, 40, and 50 are devices to be measured.

  The wireless device 10 uses, for example, an IFS (Interframe Space), which is a period during which communication is not performed in the wireless communication space 20, to transmit data at a carrier frequency of 2.4 GHz via the wireless communication space 20, for example. To wireless devices 40, 50). Then, the wireless device 10 has a timing at which data transmission to the wireless device 30 (or the wireless devices 40, 50) is completed, and a timing at which reception of data from the wireless device 30 (or the wireless devices 40, 50) is started. Between the wireless device 30 (or the wireless devices 40, 50) and a response time of the wireless device 30 (or the wireless devices 40, 50) based on the measured time and the wireless device 30 (or the wireless devices 40, 50) by a method described later. Determine the communication distance.

  The wireless device 30 (or the wireless devices 40 and 50) receives the data from the wireless device 10 via the wireless communication space 20, and sets the response time from the completion of data reception to the data transmission according to the completion of data reception. Data is measured and data including the measured response time is transmitted to the wireless device 10 via the wireless communication space 20.

  FIG. 2 is a schematic block diagram showing the configuration of the wireless device 10 shown in FIG. The wireless device 10 includes an antenna 110, selectors 120 and 240, amplifiers 130 and 290, mixers 140 and 280, low-pass filters 150 and 270, a demodulator 160, a clock adjuster 170, and a carrier detector 180. An A / D converter 190, a counter 200, a controller 210, a crystal oscillator 220, a clock generator 230, a 1 / N frequency divider 250, and a modulator 260.

  The antenna 110 receives a radio wave via the wireless communication space 20 and transmits the received radio wave to the selector 120. Further, the antenna 110 transmits the radio wave from the selector 120 to the wireless communication space 20.

  The selector 120 includes terminals 121 and 122 and a switch 123. Terminal 121 is connected to the input of amplifier 130. Terminal 122 is connected to the output of amplifier 290. The switch 123 is connected to the antenna 110. Selector 120 connects antenna 110 to the input of amplifier 130 or the output of amplifier 290 by switching switch 123 between terminals 121 and 122 based on signal SLT 1 from controller 210. More specifically, the selector 120 connects the switch 123 to the terminal 121 in response to an H (logic high) level signal SLT1 from the controller 210, and generates an L (logic low) level signal SLT1 from the controller 210. Accordingly, the switch 123 is connected to the terminal 122.

  The amplifier 130 receives the received radio wave received by the antenna 110 via the selector 120, amplifies the received received radio wave, and outputs the amplified radio wave to the mixer 140. The mixer 140 mixes the received radio wave from the amplifier 130 and the clock signal CLK_PAT from the clock adjuster 170 and outputs the mixed signal to the low-pass filter 150.

  Low-pass filter 150 removes high-frequency noise from the radio wave from mixer 140 and outputs a baseband signal to demodulator 160 and carrier detector 180. The demodulator 160 detects a frequency shift signal of the baseband signal and outputs the detected frequency shift signal to the clock adjuster 170 and the A / D converter 190. Demodulator 160 demodulates the baseband signal and outputs the demodulated data DATA to controller 210.

  The clock adjuster 170 estimates the carrier frequency of the other party of communication according to the frequency shift signal from the demodulator 160, generates a clock signal CLK_PAT having the estimated carrier frequency, and outputs it to the mixer 140 and the selector 240 To do. Carrier detector 180 detects the start of data reception based on the baseband signal from low-pass filter 150, generates signal DETS indicating the start of data reception, and outputs the signal DETS to counter 200. The carrier detector 180 detects the end of data reception based on the baseband signal from the low-pass filter 150, generates a signal DETF indicating the end of data reception, and outputs the signal DETF to the controller 210. To do.

  The A / D converter 190 converts the frequency shift signal from the demodulator 160 from an analog signal to a digital signal and outputs the data FSHT to the controller 210. Counter 200 receives signal DETS from carrier detector 180 at terminal GTE1, receives signal DTF from controller 210 at terminal GTE2, and receives clock signal CLK_SEF from clock generator 230 at terminal CLKIN. The counter 200 starts counting the number of components of the clock signal CLK_SEF received at the terminal CLKIN when receiving the signal DTF at the terminal GTE2, and ends the counting when receiving the signal DETS at the terminal GTE1. Then, the counter 200 outputs the count value CNT from the terminal Q to the controller 210.

  When the wireless device 10 receives data, the controller 210 generates an H level signal SLT1 and outputs the signal from the terminal SEL1 to the selector 120. When the wireless device 10 transmits data, the controller 210 generates an L level signal SLT1. Output from the terminal SEL1 to the selector 120.

  Further, the controller 210 generates an H level signal SLT2 when the wireless device 10 receives data and outputs the signal to the selector 240 from the terminal SEL2, and when the wireless device 10 transmits data, the controller 210 transmits an L level signal SLT2. Is output from the terminal SEL2 to the selector 240.

  Further, when the controller 210 receives the signal DETF from the carrier detector 180 at the terminal CDET, the divided clock signal from the 1 / N frequency divider 250 from the timing of receiving the signal DETF to the timing of outputting the data DATA. The response time of the wireless device 10 is measured by counting the number of components of CLK_B. Then, when measuring the response time, the controller 210 generates a packet PKT having a predetermined format including the response time, and outputs the packet PKT from the terminal TDA to the modulator 260.

  Note that the timer 211 may be built in the controller 210, and the controller 210 may measure the response time from the timing of receiving the signal DETF to the timing of outputting the packet PKT using the built-in timer 211.

  Furthermore, when transmission of data (packet PKT) is completed, controller 210 generates signal DTF indicating that transmission of data (packet PKT) is completed, and outputs the signal DTF to counter 200 from terminal TFH.

  Further, the controller 210 receives the data DATA from the demodulator 160 at the terminal RDA.

  Further, when data FSHT is received at terminal RDIF from A / D converter 190 in data communication after the end of IFS, controller 210 detects that the communication partner is moving, and communicates with the communication partner in IFS. The change in distance is measured by the method described later.

  Further, the controller 210 transmits the data DATA received at the terminal RDA to the personal computer via the terminal HOSTIF.

  The crystal oscillator 220 generates a predetermined periodic signal and outputs it to the clock generator 230. The clock generator 230 generates a clock signal CLK_SEF based on the periodic signal from the crystal oscillator 220 and outputs the generated clock signal CLK_SEF to the counter 200 and the selector 240.

  The selector 240 includes terminals 241 and 242 and a switch 243. The terminal 241 is connected to the clock adjuster 170. Terminal 242 is connected to clock generator 230. The switch 243 is connected to the 1 / N frequency divider 250 and the mixer 280. Upon receiving the H level signal SLT2 from the controller 210, the selector 240 connects the switch 243 to the terminal 241 and outputs the clock signal CLK_PAT from the clock adjuster 170 to the 1 / N frequency divider 250 and the mixer 280. . When the selector 240 receives the L level signal SLT2 from the controller 210, the selector 240 connects the switch 243 to the terminal 242 and outputs the clock signal CLK_SEF from the clock generator 230 to the 1 / N frequency divider 250 and the mixer 280. .

  The 1 / N divider 250 divides the clock signal CLK_PAT or CLK_SEF from the selector 240 by 1 / N and outputs the divided clock signal CLK_B to the controller 210.

  Modulator 260 modulates data from controller 210 (consisting of transmission data and response time) with a predetermined modulation frequency, and outputs the modulated data to low-pass filter 270. The low pass filter 270 converts the modulation data from the modulator 260 into a baseband signal and outputs the baseband signal to the mixer 280.

  The mixer 280 mixes the baseband signal from the low pass filter 270 and the clock signal CLK_PAT or CLK_SEF from the selector 240 and outputs the mixed signal to the amplifier 290. The amplifier 290 amplifies the output of the mixer 280 and outputs it to the selector 120.

  Note that the wireless devices 30, 40, and 50 shown in FIG. 1 also have the same configuration as the wireless device 10 shown in FIG.

  FIG. 3 is a timing chart of transmission data and reception data. Hereinafter, a method for determining the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) will be described. In FIG. 3, the data DATT represents data that the wireless device 10 transmits to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20, and the data DARR is the wireless device 30 (or the wireless device 40). , 50) represents data received from the wireless device 10 via the wireless communication space 20, and the data DART is transmitted from the wireless device 30 (or the wireless devices 40, 50) to the wireless device 10 via the wireless communication space 20. Data DATR represents data that the wireless device 10 receives from the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20.

  In the CSMA / CA scheme, when the wireless device 10 transmits one packet PKT_n−1, it receives an acknowledgment after a waiting time of SIFS (Short Interframe Space). Then, after receiving an affirmative response, the wireless device 10 transmits the next packet PKT_n after a waiting time of DIFS (Distributed Interframe Space) and a waiting time of BACK_OFF have elapsed.

  In the present invention, the wireless device 10 makes a round trip of data (one packet) to and from the wireless device 30 (or the wireless devices 40 and 50) using a period in which communication is not performed in the wireless communication space 20 called SIFS. Time is measured, and a communication distance with the wireless device 30 (or the wireless devices 40 and 50) is determined based on the measured round trip time.

  The wireless device 10 starts to transmit the data DATT to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20, and transmits the data DATT at the timing t1 which is the beginning of the SIFS period of the wireless communication space 20. Exit. Then, the wireless device 30 (or the wireless devices 40 and 50) starts receiving the data DARR from the wireless device 10 via the wireless communication space 20, and the wireless device 30 finishes transmitting the data DATT at the timing t2. (Or wireless devices 40, 50). That is, the time during which data is propagated from the wireless device 10 to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20 is τ1.

  When the reception of the data DARR from the wireless device 10 is completed, the wireless device 30 (or the wireless devices 40 and 50) measures the response time Tresp by the above-described method, and performs wireless communication at the timing t3 when the measurement of the response time Tresp ends. Transmission of the packet including the response time Tresp to the wireless device 10 via the space 20 is started. Then, the wireless device 10 starts receiving a packet including the response time Tresp from the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20, and the wireless device 30 (or the wireless devices 40 and 50) The transmission start of the data DATR is propagated to the wireless device 10 at timing t4. That is, the time for data to propagate from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10 via the wireless communication space 20 is τ2.

  As described above, the counter 200 of the wireless device 10 starts counting the number of components of the clock signal CLK_SEF when receiving the signal DTF at the terminal GTE2, and stops counting the number of components of the clock signal CLK_SEF when receiving the signal DETS at the terminal GTE1. To do. That is, the counter 200 counts the number of components of the clock signal CLK_SEF between timing t1 and timing t4.

  Then, by multiplying the count value CNT by the period length of the clock signal CLK_SEF, a total time Ttotal from timing t1 to timing t4 is obtained. As a result, the following equation is established.

Ttotal = τ1 + Tresp + τ2 (1)
Since the response time Tresp is measured by the controller 210 of the wireless device 30 (or the wireless devices 40 and 50) as described above, τ1 + τ2 is obtained by subtracting the response time Tresp from the total time Ttotal. This τ1 + τ2 is a round-trip time during which the packet reciprocates between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50).

  Note that since the response time Tresp measured in the wireless device 30 (or the wireless devices 40 and 50) is transmitted to the wireless device 10, the controller 210 of the wireless device 10 calculates the round-trip time τ1 + τ2 based on Expression (1). Easy to calculate.

  When the wireless device 30 (or the wireless devices 40, 50) stops moving, the propagation time τ1 in which the end of data transmission in the wireless device 10 is propagated to the wireless device 30 (or the wireless devices 40, 50) is wireless. Since the start of data transmission in the device 30 (or the wireless devices 40 and 50) is equal to the propagation time τ2 propagated to the wireless device 10, the half of the round-trip time τ1 + τ2 (τ1 + τ2) / 2 is equal to the wireless device 10 and the wireless device 30 (or This is the data propagation time between the wireless devices 40 and 50).

  Accordingly, the controller 210 of the wireless device 10 determines the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) by multiplying the time (τ1 + τ2) / 2 by the speed of light c.

  Since the response time Tresp is a fixed value in each of the radio apparatuses 30, 40, and 50, as is apparent from FIG. 3, the total time Ttotal is increased by the data propagation times τ1 and τ2.

  Therefore, the present invention utilizes the fact that the total time Ttotal is increased by the data propagation times τ1, τ2 between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50). 30 (or wireless devices 40, 50) is determined.

  Communication between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) includes seven layers of a physical layer, a data link layer, a network layer, a transport layer, a session layer, a presentation layer, and an application layer. The wireless device 30 (or the wireless devices 40 and 50) performs a packet including the measured response time Tresp in the physical layer (media access layer) by using a plurality of protocols corresponding to an OSI (Open Systems Interconnection) reference model. The packet is generated according to the format in the protocol, and the generated packet is transmitted to the wireless device 10 according to the protocol of the physical layer. Note that the protocol of any layer may be used for the measurement of the total time Ttotal.

  The structure of a packet generated according to the format in the physical layer (media access layer) protocol will be described.

  FIG. 4 is a conceptual diagram of a packet used when measuring a communication distance between two wireless devices. 4A illustrates a conceptual diagram of a packet transmitted from the wireless device 10 that is a communication distance measuring device to the wireless device 30 (or the wireless devices 40 and 50) that is a communication distance measuring device. (B) of FIG. 4 represents a conceptual diagram of a packet transmitted from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10.

  The instruction packet INST transmitted from the wireless device 10 to the wireless device 30 (or the wireless devices 40 and 50) includes a frame control unit 31, a length unit 32, a reception side address unit (RA) 33, and a transmission side address unit ( TA) 34 and a frame check sequence part (FCS) 35 (see (a) of FIG. 4).

  The frame control unit 31 indicates that the instruction packet INST is a packet instructing measurement of response time in the wireless device 30 (or the wireless devices 40 and 50). The frame control unit 31 has a length of 2 bytes and consists of [0011].

  The length portion 32 represents the entire length of the instruction packet INST and has a length of 2 bytes. The receiving-side address unit 33 represents the address of the wireless device 30 (or the wireless devices 40 and 50) that receives the instruction packet INST, and has a length of 6 bytes. The transmission-side address unit 34 represents the address of the wireless device 10 that transmits the instruction packet INST, and has a length of 6 bytes.

  The frame check sequence unit 35 is for checking the entire error of the instruction packet INST, and has a length of 4 bytes.

  The reply packet RESP includes a frame control unit 41, a length unit 42, a receiving side address unit (RA) 43, a response time data unit (nSIFS) 44, and a frame check sequence unit (FCS) 45 (see FIG. 4 (b)).

  The frame control unit 41 indicates that the reply packet RESP is a packet including a response time measured in the wireless device 30 (or the wireless devices 40 and 50). The reply packet RESP has a length of 2 bytes and consists of [0100].

  The length part 42 represents the entire length of the reply packet RESP and has a length of 2 bytes. The receiving side address unit 43 represents the address of the wireless device 10 that receives the reply packet RESP, and has a length of 6 bytes. The reception side address part 43 stores the address acquired from the transmission side address part 34 of the instruction packet INST. The response time data unit 44 includes data representing the response time measured in the wireless device 30 (or the wireless devices 40 and 50) in units of nsec, and has a length of 2 bytes.

  The frame check sequence unit 45 is for checking the entire error of the reply packet RESP, and has a length of 4 bytes.

  The instruction packet INST and the reply packet RESP correspond to an RTS (Request To Send) frame and a CTS (Clear To Send) frame, which are IEEE 802.11 frames that are one of the protocols in the wireless LAN. The instruction packet INST has the same format as the RTS frame, and the reply packet RESP has the same format as the CTS frame. Therefore, the instruction packet INST and the reply packet RESP are generated according to the protocol of the physical layer (media access layer) which is the lowest layer protocol among the plurality of protocols.

  In IEEE 802.11, the frame control unit of the RTS frame is composed of [1011]. In the present invention, however, the instruction packet INST is changed to [0011] that is not used in IEEE802.11 by changing [1011] to the wireless device. 30 (or wireless device 40, 50) indicates that the packet is an instruction to measure the response time.

  In IEEE 802.11, the frame control unit of the CTS frame is composed of [1100]. In the present invention, however, the reply packet RESP is changed by replacing [1100] with [0100] unused in IEEE 802.11. This represents a packet including the response time measured in the wireless device 30 (or wireless devices 40, 50), and the wireless device 30 (or wireless devices 40, 50) is used in place of the transmission side address portion (TA) of the CTS frame. The response time data part 44 representing the response time measured in is used as a constituent element.

  Thus, since the instruction packet INST and the reply packet RESP have a format according to IEEE 802.11, the wireless device 10 transmits the instruction packet INST to the wireless device 30 (or the wireless devices 40 and 50), and the reply packet RESP. Communication from the wireless device 30 (or the wireless devices 40 and 50) can be performed according to IEEE 802.11.

  FIG. 5 is a conceptual diagram showing a communication distance measuring method using the instruction packet INST and the reply packet RESP shown in FIG. The wireless device 10 that is the communication distance measuring terminal transmits the instruction packet INST to the wireless device 30 (or the wireless devices 40 and 50) that is the measured terminal, and has been described above according to the end of transmission of the instruction packet INST. The measurement of the total time Ttotal is started by the method. Then, the end of transmission of the instruction packet INST is transmitted to the wireless device 30 (or the wireless devices 40 and 50) after time τ1.

  When the wireless device 30 (or the wireless devices 40 and 50) receives the instruction packet INST from the wireless device 10, the wireless device 30 (or the wireless devices 40 and 50) detects [0011] of the frame control unit 31 of the instruction packet INST and confirms that the response time is instructed. The measurement of the response time is started in response to the end of reception of the instruction packet INST.

  When the measurement of the response time (SIFS) is completed, the wireless device 30 (or the wireless devices 40 and 50) generates a reply packet RESP in which the measured response time (SIFS) is stored in the response time data unit 44, and the wireless device 10 Send to. Then, the transmission start of the reply packet RESP is transmitted to the wireless device 10 after time τ2.

  When the wireless device 10 detects the start of reception of the reply packet RESP, the wireless device 10 ends the time measurement and obtains the total time Ttotal by the method described above. Then, the wireless device 10 extracts the response time (SIFS) from the response time data part 44 of the reply packet RESP, and uses the extracted response time (SIFS) and the obtained total time Ttotal to perform wireless communication by the method described above. The communication distance with the device 30 (or the wireless devices 40 and 50) is determined.

  FIG. 6 is a flowchart for explaining the operation of determining the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50). When a series of operations is started, the controller 210 of the wireless device 10 generates an L level signal SLT1 and outputs it to the selector 120, and generates an L level signal SLT2 and outputs it to the selector 240. Then, the selector 120 connects the switch 123 to the terminal 122 in accordance with the L level signal SLT1. The selector 240 connects the switch 243 to the terminal 242 in response to the L level signal SLT2.

  On the other hand, the controller 210 of the wireless device 30 (or the wireless devices 40 and 50) generates an H level signal SLT1 and outputs it to the selector 120, and generates an H level signal SLT2 and outputs it to the selector 240. Then, the selector 120 connects the switch 123 to the terminal 121 in accordance with the H level signal SLT1. The selector 240 connects the switch 243 to the terminal 241 in response to the H level signal SLT2.

  The controller 210 of the wireless device 10 generates an instruction packet INST and outputs the generated instruction packet INST to the modulator 260 from the terminal TDA. Modulator 260 modulates instruction packet INST from controller 210 with a predetermined modulation frequency and outputs the modulated packet to low pass filter 270. The low pass filter 270 removes high frequency noise from the modulation data and outputs a baseband signal to the mixer 280.

  The crystal oscillator 220 of the wireless device 10 generates a predetermined periodic signal and outputs it to the clock generator 230. The clock generator 230 generates a clock signal CLK_SEF based on the periodic signal and outputs it to the counter 200 and the selector 240. Then, the selector 240 outputs the clock signal CLK_SEF to the 1 / N frequency divider 250 and the mixer 280. The mixer 280 mixes the baseband signal from the low pass filter 270 and the clock signal CLK_SEF from the selector 240 and outputs the mixed signal to the amplifier 290. That is, the mixer 280 outputs the baseband signal to the amplifier 290 in synchronization with the clock signal CLK_SEF. The amplifier 290 amplifies the output of the mixer 280 and outputs it to the selector 120. The selector 120 transmits the output of the amplifier 290 via the antenna 110. Thereby, transmission of the instruction packet INST to the wireless device 30 (or the wireless devices 40 and 50) is started (step S1).

  Thereafter, the instruction packet INST is transmitted to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20, and when the transmission of the instruction packet INST in the wireless device 10 is completed (step S2), the controller of the wireless device 10 210 generates a signal DTF and outputs it to the counter 200 from the terminal TFH. When the counter 200 receives the signal DTF at the terminal GTE2, the counter 200 starts counting the number of components of the clock signal CLK_SEF (step S3).

  The instruction packet INST transmitted from the wireless device 10 is transmitted to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20. The antenna 110 of the wireless device 30 (or the wireless devices 40 and 50) supplies the instruction packet INST received via the wireless communication space 20 to the amplifier 130 via the selector 120. The amplifier 130 amplifies the instruction packet INST supplied from the selector 120 and outputs it to the mixer 140. The mixer 140 mixes the output of the amplifier 130 and the clock signal CLK_PAT from the clock adjuster 170 and outputs the mixed signal to the low-pass filter 150. That is, the mixer 140 outputs the baseband signal to the low-pass filter 150 in synchronization with the clock signal CLK_PAT. The low pass filter 150 removes high frequency noise from the output of the mixer 140 and outputs a baseband signal to the demodulator 160 and the carrier detector 180.

  The demodulator 160 detects a frequency shift signal of the baseband signal and outputs the detected frequency shift signal to the clock adjuster 170 and the A / D converter 190. Demodulator 160 demodulates the baseband signal and outputs the demodulated instruction packet INST to controller 210. The clock adjuster 170 estimates the carrier frequency of the radio apparatus 10 according to the frequency shift signal from the demodulator 160, generates a clock signal CLK_PAT having the estimated carrier frequency, and outputs the clock signal CLK_PAT to the mixer 140 and the selector 240. . As a result, the wireless device 30 (or the wireless devices 40 and 50) receives the instruction packet INST in synchronization with the clock signal CLK_SEF generated in the wireless device 10 that is the communication partner (step S4).

  When receiving the instruction packet INST from the demodulator 160, the controller 210 of the wireless device 30 (or the wireless devices 40 and 50) detects [0011] from the frame control unit 31 of the instruction packet INST and is instructed to measure the response time. Is detected.

  Further, the carrier detector 180 of the wireless device 30 (or the wireless devices 40 and 50) detects that the reception of the instruction packet INST has ended based on the baseband signal from the low-pass filter 150 (step S5), A signal DETF indicating completion of reception of the packet INST is generated and output to the controller 210.

  Further, the selector 240 of the wireless device 30 (or the wireless devices 40 and 50) outputs the clock signal CLK_PAT from the clock adjuster 170 to the 1 / N frequency divider 250 and the mixer 280. The 1 / N frequency divider 250 divides the clock signal CLK_PAT by 1 / N and outputs the divided clock signal CLK_B to the controller 210.

  Then, the controller 210 of the wireless device 30 (or the wireless devices 40 and 50) synchronizes with the timing at which the signal DETF is received at the terminal CDET from the carrier detector 180, and the number of components of the divided clock signal CLK_B received at the terminal MCLK. The response time Tresp from the timing of receiving the signal DETF to the timing of outputting the reply packet RESP is measured (step S6).

  As described above, the wireless device 30 (or the wireless devices 40 and 50) measures the response time Tresp based on the clock signal CLK_PAT having the carrier frequency of the wireless device 10 estimated by the clock adjuster 170.

  In step S6, the controller 210 may measure the response time Tresp from the timing of receiving the signal DETF to the timing of outputting the reply packet RESP by the built-in timer 211.

  Thereafter, the controller 210 of the wireless device 30 (or the wireless devices 40 and 50) generates an L-level signal SLT1 and outputs the signal to the selector 120. The selector 120 switches the switch 123 according to the L-level signal SLT1. Connect to terminal 122.

  When the measurement of the response time Tresp ends, the controller 210 of the wireless device 30 (or the wireless devices 40 and 50) stores the response time Tresp in the response time data unit 44 to generate a response packet RESP, and the generated response packet RESP is output from the terminal TDA to the modulator 260. Then, the modulator 260 modulates the reply packet RESP with a predetermined modulation frequency. The low pass filter 270 removes high frequency noise from the modulation data and outputs a baseband signal to the mixer 280. The mixer 280 mixes the baseband signal from the low pass filter 270 and the clock signal CLK_PAT from the selector 240 and outputs the mixed signal to the amplifier 290. That is, the mixer 280 outputs the baseband signal to the amplifier 290 in synchronization with the clock signal CLK_PAT. The amplifier 290 amplifies the output of the mixer 280 and outputs it to the selector 120. The selector 120 transmits the output of the amplifier 290 via the antenna 110. Thereby, transmission of the reply packet RESP from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10 is started (step S7).

  As described above, the wireless device 30 (or the wireless devices 40 and 50) transmits and receives the instruction packet INST from the wireless device 10 in synchronization with the clock signal CLK_PAT having the same carrier frequency as the carrier frequency in the wireless device 10.

  Thereafter, the controller 210 of the wireless device 10 generates an H-level signal SLT1 and outputs it to the selector 120. The selector 120 connects the switch 123 to the terminal 121 in accordance with the H level signal SLT1.

  Then, the antenna 110 of the wireless device 10 supplies the reply packet RESP received via the wireless communication space 20 to the amplifier 130 via the selector 120. The amplifier 130 amplifies the reply packet RESP supplied from the selector 120 and outputs it to the mixer 140. The mixer 140 mixes the output of the amplifier 130 and the clock signal CLK_PAT from the clock adjuster 170 and outputs the mixed signal to the low-pass filter 150. The low pass filter 150 removes high frequency noise from the output of the mixer 140 and outputs a baseband signal to the demodulator 160.

  The demodulator 160 demodulates the baseband signal and outputs the demodulated reply packet RESP to the controller 210. Thereby, the radio | wireless apparatus 10 starts reception of the reply packet RESP from the radio | wireless apparatus 30 (or radio | wireless apparatuses 40 and 50) (step S8).

  Based on the baseband signal from the low-pass filter 150, the carrier detector 180 detects that the reception of the reply packet RESP from the wireless device 30 (or the wireless devices 40 and 50) has started, and the response packet RESP A signal DETS indicating the start of reception is generated and output to the counter 200.

  When the counter 200 receives the signal DETS from the carrier detector 180 to the terminal GTE1, the counter 200 finishes counting the number of components of the clock signal CLK_SEF, and outputs the count value CNT from the terminal Q to the controller 210. When the controller 210 receives the count value CNT at the terminal TAV, the controller 210 calculates the cycle length of the clock signal CLK_SEF based on the divided clock signal CLK_B (in the wireless device 10, the divided clock signal CLK_B divides the clock signal CLK_SEF). The total time Ttotal is calculated by multiplying the calculated cycle length by the count value CNT (step S9).

  When the controller 210 calculates the total time Ttotal, the controller 210 extracts the response time Tresp from the response time data part 44 of the reply packet RESP received from the wireless device 30 (or the wireless devices 40, 50), and the extracted response time Tresp is totaled. The round trip time τ1 + τ2 is calculated by subtracting from the time Ttotal. Then, the controller 210 multiplies half of the round-trip time τ1 + τ2 (τ1 + τ2) / 2 by the speed of light c to determine the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50) (step S10). ).

  Thereby, a series of operations are completed.

  As described above, the wireless device 30 (or the wireless devices 40 and 50) measures the response time Tresp based on the clock signal CLK_PAT having the carrier frequency of the wireless device 10 that is the communication partner (see step S6). Further, the wireless device 30 (or the wireless devices 40 and 50) synchronizes the data (instruction packet INST and reply packet RESP) from the wireless device 10 with a clock signal CLK_PAT having the same carrier frequency as the carrier frequency in the wireless device 10. Transmit and receive (see steps S4 and S7).

  Therefore, the data reception end timing, the response time Tresp length, and the data transmission start timing in the wireless device 30 (or the wireless devices 40 and 50) are determined in synchronization with the clock signal CLK_SEF generated in the wireless device 10. The radio apparatus 10 can accurately measure the total time Ttotal = τ1 + Tresp + τ2. As a result, the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) can be accurately determined.

  Further, since the wireless device 10 receives the actually measured response time Tresp from the wireless device 30 (or the wireless devices 40, 50), even if the response time Tresp is different in each of the wireless devices 30, 40, 50, the wireless device 10 The communication distance with each of the devices 30, 40, 50 can be accurately determined.

  FIG. 7 is a diagram illustrating the relationship between the actually measured total time Ttotal and the communication distance. FIG. 7A shows a case where the response time Tresp of the wireless device 30 (or the wireless devices 40 and 50), which is a device to be measured for communication distance, is constant, and FIG. 7B shows the communication distance. The case where the response time Tresp of the wireless device 30 (or the wireless devices 40 and 50), which is a device under test, is not constant is shown. 7A and 7B, the vertical axis represents the total time Ttotal, and the horizontal axis represents the communication distance.

  As shown in FIG. 7A, when the response time Tresp of the wireless device 30 (or the wireless devices 40, 50) is constant, the total time Ttotal is equal to the wireless device 10 and the wireless device 30 (or the wireless devices 40, 40). 50) in accordance with the communication distance. More specifically, the total time Ttotal becomes longer in proportion to the communication distance in the range where the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) is up to 350 m.

  As described above, the total time Ttotal is expressed by τ1 + Tresp + τ2, and changes according to the data propagation times τ1 and τ2 between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50). The propagation times τ1 and τ2 change in proportion to the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50). As a result, the total time Ttotal changes in proportion to the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50).

  Therefore, the actually measured total time Ttotal reflects that the data propagation times τ1 and τ2 have become longer according to the communication distance.

  On the other hand, as shown in FIG. 7B, when the response time Tresp of the wireless device 30 (or the wireless devices 40 and 50) is not constant, the total time Ttotal is equal to the wireless device 10 and the wireless device 30 (or the wireless device 40). , 50) is not proportional to the communication distance.

  When the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) is about 230 m and about 340 m, there are a plurality of total times Ttotal for each communication distance. This is the same model as the wireless device 30 (or the wireless devices 40 and 50), but the wireless device 30 (or the wireless device 40) is programmed by a microprocessor program built in the wireless device 30 (or the wireless devices 40 and 50). , 50) changes in response time.

  Accordingly, as in the present invention, the wireless device 30 (or wireless devices 40, 50) measures its own response time Tresp and transmits it to the wireless device 10, and the wireless device 10 (or wireless devices 40, 50). ) Is used to calculate the propagation time τ1 + τ2 in which the data (packet) propagates between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50) by using the response time Tresp received from the wireless device 30 ( Alternatively, the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50) can be accurately determined even if the response time Tresp of the wireless devices 40, 50) changes variously.

  In the above, when the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) is measured using SIFS (SIFS shown in FIG. 3) in the wireless LAN system using the CSMA_CA method. As described above, the present invention is not limited to this, and the wireless device 10 and the wireless device 10 can be wirelessly connected using a PIFS (Point Coordination Function IFS) or DIFS (DIFS shown in FIG. 3) longer than SIFS in the wireless LAN system using the CSMA_CA method. You may measure the communication distance between the apparatuses 30 (or radio | wireless apparatuses 40 and 50).

  The wireless device 10 determines the communication distance between the wireless device 30 (or the wireless devices 40 and 50) by the above-described method using the period (IFS) in which communication is not performed in the wireless communication space 20, that is, After the end of the non-communication period, data communication is performed with the wireless device 30 (or wireless devices 40, 50), and the phase of the data transmitted to the wireless device 30 (or wireless devices 40, 50) is the wireless device 30. It is determined whether or not the phase of the data received from (or the wireless devices 40 and 50) is shifted. When the phase of the data transmitted to the wireless device 30 (or the wireless devices 40 and 50) is shifted from the phase of the data received from the wireless device 30 (or the wireless devices 40 and 50), the wireless device 10 30 (or wireless devices 40, 50) is determined to be moving, and the change in the communication distance with wireless device 30 (or wireless devices 40, 50) during the idle period is measured.

  More specifically, the wireless device 10 transmits data to the wireless device 30 (or the wireless devices 40 and 50) in synchronization with the clock signal CLK_SEF generated by the wireless device 10 by the method described above. Then, the wireless device 30 (or the wireless devices 40 and 50) transmits the data received from the wireless device 10 to the wireless device 10 in synchronization with the clock signal CLK_SEF generated by itself. During normal data communication, the wireless device 30 (or the wireless devices 40 and 50) is not the clock signal CLK_SEF (= CLK_PAT) generated by the wireless device 10 that is the communication partner, but the clock signal CLK_SEF generated by itself. Send data in sync with.

  The clock signal CLK_SEF generated in the wireless device 10 is referred to as a clock signal CLK_SEF_T, and the clock signal CLK_SEF generated in the wireless device 30 (or the wireless devices 40 and 50) is referred to as a clock signal CLK_SEF_R. Further, data transmitted from the wireless device 10 to the wireless device 30 (or the wireless devices 40 and 50) in synchronization with the clock signal CLK_SEF_T is referred to as DATA_T, and the wireless device 30 (or the wireless devices 40 and 50) is synchronized with the clock signal CLK_SEF_R. The data transmitted to the wireless device 10 is DATA_R.

  As a result, the wireless device 10 transmits data DATA_T to the wireless device 30 (or wireless devices 40, 50) and receives data DATA_R from the wireless device 30 (or wireless devices 40, 50). Then, the wireless device 10 determines whether or not the phase of the data DATA_T is shifted from the phase of the data DATA_R.

  That is, the demodulator 160 of the wireless device 10 detects the frequency shift signal of the data DATA_R received from the wireless device 30 (or the wireless devices 40 and 50), that is, the phase shift of the data DATA_R, and sends it to the A / D converter 190. Output. A / D converter 190 converts the phase shift from demodulator 160 from an analog signal to a digital signal, and outputs data FSHT to controller 210. Accordingly, the A / D converter 190 generates the phase shift data FSHT and outputs it to the controller 210.

  Controller 210 detects that a phase shift has occurred in data DATA_R by receiving data FSHT at terminal RDIF. Then, when a phase shift occurs in the data DATA_R, the controller 210 measures the change in the communication distance with the wireless device 30 (or the wireless devices 40 and 50) during the idle period by the following method.

  Since the propagation time τ1 is equal to the propagation time τ2 when the wireless device 30 (or the wireless devices 40, 50) stops moving, the data is transmitted to the wireless device 10 and the wireless device 30 (or the wireless device) when the total time is Ttotal1. The round trip time to and from the devices 40, 50) can be expressed by 2τ1 = a (= Ttotal1-Tresp). In addition, when the wireless device 30 (or the wireless devices 40 and 50) is moving, if the total time is Ttotal2, data reciprocates between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50). The round trip time can be expressed as τ1 + τ2 = b (= Ttotal2-Tresp).

  Therefore, from these two expressions, | τ1−τ2 | = | a−b |, and the change in the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) during the idle period is | a −b | × c.

  The controller 210 of the wireless device 10 stores the round trip time a when the wireless device 30 (or the wireless devices 40, 50) is stopped, and the wireless device 30 (or the wireless devices 40, 50) moves. When it is determined that the communication distance is present, the communication distance change | ab− × c is calculated using the measured round-trip time b as described above.

  Note that determining that the phase of the data DATA_R received from the wireless device 30 (or the wireless devices 40, 50) is shifted from the phase of the data DATA_T transmitted to the wireless device 30 (or the wireless devices 40, 50) This corresponds to determining that the phase of the clock signal CLK_SEF_R generated in the device 30 (or the wireless devices 40 and 50) is shifted from the phase of the clock signal CLK_SEF_T generated in the wireless device 10. This is because the data DATA_R is synchronized with the clock signal CLK_SEF_R, and the data DATA_T is synchronized with the clock signal CLK_SEF_T.

  In general, the modulation frequency for modulating data is equal to the carrier frequency (carrier frequency) of the clock signals CLK_SEF and CLK_PAT, but the modulation frequency may be different from the carrier frequency. CLK_SEF and CLK_PAT may be generated based on either the modulation frequency or the carrier frequency.

  In the present invention, the wireless device 10 constitutes a “transmitter”, and the wireless device 30 (or the wireless devices 40 and 50) constitutes a “receiver”.

  As described above, the wireless device 10 receives the response time measured in the wireless device 30 (or the wireless devices 40 and 50) from the wireless device 30 (or the wireless devices 40 and 50) and determines the communication distance. Even if the instruction packet INST and the reply packet RESP are transmitted and received between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) using the DIFS during which communication is not performed in the wireless communication space 20, communication is possible. You can determine the distance.

  That is, as shown in FIG. 3, DIFS is accompanied by BACK_OFF, and this BACK_OFF is variable. Therefore, when the response time in the wireless device 30 (or the wireless devices 40 and 50) is not actually measured, the time length of DIFS cannot be determined and the communication distance cannot be determined. Since the response time in 30 (or the wireless devices 40 and 50) is actually measured, even when a DIFS having a variable time length is used, the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) are also connected. Communication distance can be determined.

  Therefore, in the present invention, even if any of SIFS, PIFS, and DIFS, which are periods during which communication is not performed in the wireless communication space 20, is used, the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) are not connected. Communication distance can be determined.

[Embodiment 2]
FIG. 8 is a schematic block diagram illustrating a configuration of the wireless device according to the second embodiment. In the second embodiment, the wireless device 10 includes the wireless device 11 shown in FIG. The wireless device 11 is the same as the wireless device 10 except that the controller 210 of the wireless device 10 shown in FIG.

  The controller 210A performs control so that normal data DATA is transmitted to another wireless device using a period (SIFS, PIFS, and DIFS) in which communication is not performed in the wireless communication space 20. Each time the controller 210A transmits the data DATA to another wireless device, the controller 210A measures the total time from the end of transmission of the data DATA to the start of reception of response data to the data DATA, and stores the measured total time.

  Further, the controller 210A receives data DATA from another wireless device, and measures and stores the response time from the completion of reception of data DATA to the transmission of response data for the data DATA every time reception completion of data DATA is detected. To do. Furthermore, when determining the communication distance with another wireless device, the controller 210A controls to generate an instruction packet INST shown in FIG. 4A and transmit it to the other wireless device. Then, the controller 210A receives a reply packet to be described later from another wireless device, extracts a plurality of response times included in the received reply packet, and determines a communication distance with the other wireless device by a method to be described later. .

  Furthermore, when receiving the instruction packet INST, the controller 210A generates and transmits a reply packet RESP * including a plurality of response times measured and stored until the instruction packet INST is received.

  The wireless devices 30, 40 and 50 have the same configuration as the wireless device 11.

  FIG. 9 is a configuration diagram of a reply packet in the second embodiment. The reply packet RESP * in the second embodiment is the same as the reply packet RESP except that the reply time data part 44 of the reply packet RESP shown in FIG. 4B is replaced with the reply time data part 44A. is there.

  The response time data part 44A includes a number part 440 and data parts 441 to 44n (n is a natural number). The number part 440 represents the number of measured response times, and has a length of 2 bytes. Each of the data parts 441 to 44n represents a measured response time and has a length of 2 bytes.

  The reply packet RESP * is also a packet generated according to the IEEE 802.11 physical layer protocol.

  FIG. 10 is a conceptual diagram illustrating a communication distance determination method according to the second embodiment. When the wireless devices 10, 30, 40, and 50 are composed of the wireless device 11 shown in FIG. 8, the wireless device 10 that is a communication distance measurement-side terminal transmits normal data DATA1 to the wireless device 30 (or the measured-side terminal). Wireless device 40, 50), and in response to the end of transmission of data DATA1, measurement of total time Ttotal1 is started by the method described above. Then, the end of transmission of the data DATA1 is transmitted to the wireless device 30 (or the wireless devices 40 and 50) after time τ1.

  When the wireless device 30 (or the wireless devices 40 and 50) receives the data DATA1 from the wireless device 10, the wireless device 30 (or the wireless devices 40 and 50) starts measuring the response time in response to the end of reception of the data DATA1.

  When the measurement of the response time (DIFS) is completed, the wireless device 30 (or the wireless devices 40 and 50) stores the measured response time (DIFS), generates response data DATA2 in response to the data DATA1, and generates the response data DATA2. Send to. Then, the transmission start of the response data DATA2 is transmitted to the wireless device 10 after time τ2.

  When the wireless device 10 detects the start of reception of the data DATA2, the wireless device 10 ends the time measurement and obtains the total time Ttotal1 by the method described above.

  The normal data transmission / reception described above is repeated between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50). The wireless device 10 measures and stores a plurality of total times, and the wireless device 30 (Or wireless devices 40 and 50) measure and store a plurality of response times.

  When the wireless device 10 determines the communication distance with the wireless device 30 (or the wireless devices 40, 50), the wireless device 10 transmits the instruction packet INST to the wireless device 30 (or the wireless devices 40, 50). In response to the end of transmission, measurement of the total time Ttotal is started by the method described above. Then, the end of transmission of the instruction packet INST is propagated to the wireless device 30 (or the wireless devices 40 and 50) after time τ1.

  When receiving the instruction packet INST from the wireless device 10, the wireless device 30 (or the wireless devices 40 and 50) detects [0011] of the frame control unit 31 of the instruction packet INST and is instructed to measure and transmit the response time. When the reception of the instruction packet INST is completed, time measurement is started.

  When the measurement of the response time (SIFS) is completed, the wireless device 30 (or the wireless devices 40 and 50) uses the response time data part 44A as a plurality of response times Tresp1 to Trespn measured until the reply packet RESP * is transmitted. A reply packet RESP * stored in each of the units 441 to 44n and storing the number n of response times Tresp1 to Trespn in the number unit 440 is generated and transmitted to the radio apparatus 10. Then, the transmission start of the reply packet RESP * is transmitted to the wireless device 10 after time τ2.

  When detecting the start of reception of the reply packet RESP *, the wireless device 10 ends the time measurement and obtains the total time Ttotal by the method described above. Then, the wireless device 10 extracts a plurality of response times Tresp1 to Trespn from the response time data portion 44A of the reply packet RESP *, and calculates an average value Tresp_ave of the extracted response times Tresp1 to Trespn. In addition, the wireless device 10 calculates an average value Ttotal_ave of a plurality of total times Ttotal1 to Ttotal measured by itself.

  Then, the wireless device 10 determines the communication distance with the wireless device 30 (or the wireless devices 40 and 50) by the above-described method using the average value Tresp_ave of the response time Tresp and the average value Ttotal_ave of the total time Ttotal.

  FIGS. 11 and 12 are first and second flowcharts, respectively, for explaining the operation in the second embodiment for determining the communication distance between two wireless devices.

  In steps S11 to S19 shown in FIG. 11, in step S1 to step S9 of the flowchart shown in FIG. 6, the instruction packet INST is replaced with data DATA1, the reply packet RESP is replaced with response data DATA2, and step S7 is replaced with step S17. It corresponds to that.

  In step S17, the wireless device 30 (or the wireless devices 40 and 50) starts transmitting response data DATA2 to the data DATA1 after the response time has elapsed.

  As described above, in steps S11 to S19 shown in FIG. 11, the total time Ttotal1 in which data reciprocates between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50) is wirelessly transmitted using normal data. It represents that the device 10 measures and the wireless device 30 (or the wireless devices 40 and 50) measures its own response time Tresp1.

  Then, after step S19, the controller 210A of the wireless device 10 determines whether or not to determine the communication distance with the wireless device 30 (or the wireless devices 40 and 50) (step S20) and does not determine the communication distance. Steps S11 to S19 are repeatedly executed.

  If it is determined in step S20 that the communication distance is determined, steps S21 to S30 shown in FIG. 12 are executed. Steps S21 to S26, S28, and S29 shown in FIG. 12 are the same as steps S1 to S6, S8, and S9 shown in FIG.

  When the wireless device 30 (or the wireless devices 40 and 50) finishes measuring the response time Trespn in step S26, the wireless device 30 (or the wireless devices 40 and 50) outputs n response times Tresp1 to Trespn measured until the reply packet RESP * is transmitted to the response time data portion 44A. The response packet RESP * is stored in the data portions 441 to 44n and the number n of the response times Tresp1 to Trespn is stored in the number portion 440, and is transmitted to the wireless device 10 (step S27).

  Further, when the wireless device 10 finishes measuring the total time Ttotal in step S29, the wireless device 10 calculates the average value Tresp_ave of the response time Tresp using the n response times Tresp1 to Trespn included in the reply packet RESP * and the number n. Then, the n total times Ttotal1 to Ttotaln stored therein are read and the average value Ttotal_ave of the n total times Ttotal1 to Ttotaln is calculated. Then, the wireless device 10 determines the communication distance with the wireless device 30 (or the wireless devices 40 and 50) by the above-described method using the average value Tresp_ave of the response time Tresp and the average value Ttotal_ave of the total time Ttotal ( Step S30).

  Thereby, a series of operation | movement is complete | finished.

  As described above, in the second embodiment, the wireless device 10 that measures the communication distance transmits the normal data to the wireless device using various periods (SIFS, PIFS, DIFS) that are not communicated in the wireless communication space 20. 30 (or wireless devices 40, 50), and the time that data travels back and forth between the wireless device 10 and the wireless device 30 (or wireless devices 40, 50) is measured and stored. (Or the wireless devices 40 and 50) measure and store their own response time. When determining the communication distance, the wireless device 10 transmits / receives a packet (instruction packet INST and reply packet RESP *) for determining the communication distance to / from the wireless device 30 (or the wireless devices 40 and 50). The communication distance is determined using a plurality of round trip times measured so far and a plurality of response times in the wireless device 30 (or the wireless devices 40 and 50).

  Thereby, the radio | wireless apparatus 10 can measure the communication distance between the radio | wireless apparatuses 30 (or radio | wireless apparatuses 40 and 50) correctly at arbitrary timings.

  Others are the same as in the first embodiment.

[Embodiment 3]
FIG. 13 is a schematic block diagram illustrating a configuration of a wireless device according to the third embodiment. A wireless device 10 that is a communication distance measuring machine includes wireless LAN hardware 101 and a personal computer 102. The wireless device 30 that is a device to be measured for communication distance includes wireless LAN hardware 301 and a personal computer 302.

  The wireless LAN hardware 101 and 301 has the same configuration as that shown in FIG. The personal computer 102 includes a response time acquisition unit 1021, a communication distance determination unit 1022, and a hard disk 1023.

  The wireless LAN hardware 101 uses the various periods (SIFS, PIFS, DIFS) during which no communication is performed in the wireless communication space 20 to sequentially transfer normal data DATA1, DATA2,. Send and receive with. When the wireless LAN hardware 101 transmits / receives one piece of data DATA1 to / from the wireless device 30, the wireless LAN hardware 101 measures the total time Ttotal1 by the method described above, and uses the measured total time Ttotal1 as the frame sequence number ( The data is stored in the hard disk 1023 of the personal computer 102 in association with FSN = 1). The wireless LAN hardware 101 executes this for n pieces of data DATA1 to DATAn, thereby obtaining n total times Ttotal1, Ttotal2,..., Ttotal corresponding to the n pieces of data DATA1 to DATAn as frame sequence numbers. The data are sequentially stored in the hard disk 1023 in association with FSN = 1, 2,..., N.

  The response time acquisition unit 1021 requests a history of the response time Tresp measured in the wireless device 30 to the wireless device 30 that is a device to be measured for communication distance, and wirelessly transmits the history of the response time Tresp by TCP / IP communication. A response time acquisition program received from the device 30 is held. Then, the response time acquisition unit 1021 executes the response time acquisition program to request a history of the response time Tresp from the wireless device 30 by TCP / IP communication, and the frame sequence number FSN = 1, 2,. , N and response times Tresp1 to Trespn are received from the wireless device 30 and output to the communication distance determining unit 1022.

  The communication distance determination unit 1022 receives the response times Tresp1 to Trespn associated with the frame sequence numbers FSN = 1, 2,..., N received from the response time acquisition unit 1021, and the frame sequence read from the hard disk 1023. .., N are associated with the total time Ttotal1, Ttotal2,..., Ttotal associated with the number FSN = 1, 2,. The communication distance to the wireless device 30 in each period (SIFS, PIFS, DIFS) in which communication is not performed in the wireless communication space 20 is determined by the method described above.

  The hard disk 1023 sequentially stores the frame sequence number FSN = j (j = 1 to n) received from the wireless LAN hardware 101 and the corresponding total time Ttotalj. That is, the hard disk 1023 stores a history HIS_T of the total time measured by the wireless LAN hardware 101.

  The personal computer 302 includes a response time transmission unit 3021 and a hard disk 3022.

  When the wireless LAN hardware 301 receives the data DATA1 from the wireless device 10, the wireless LAN hardware 301 measures the response time Tresp1 by the above-described method in synchronization with the end of reception of the data DATA1, and uses the measured response time Tresp1 as the frame sequence of the data DATA1. The information is stored in the hard disk 3022 of the personal computer 302 in association with the number FSN = 1.

  The wireless LAN hardware 301 executes this for n pieces of data DATA1 to DATAn, thereby obtaining n response times Tresp1, Tresp2,..., Trespn corresponding to the n pieces of data DATA1 to DATAn as frame sequence numbers. The data are sequentially stored in the hard disk 3022 in association with FSN = 1, 2,..., N.

  The response time transmission unit 3021 holds a response time transmission program that transmits a response time history to the wireless device 10 in response to a response time transmission request from the wireless device 10 by TCP / IP communication. Then, the response time transmission unit 3021 executes this response time transmission program, thereby receiving a transmission request from the wireless device 10 by TCP / IP communication. For the reception of the transmission request, the frame sequence number FSN = 1, Response times Tresp1 to Trespn associated with 2,..., N are read from the hard disk 3022 and transmitted to the wireless device 10.

  The hard disk 3022 sequentially stores the frame sequence number FSN = j received from the wireless LAN hardware 301 and the corresponding response time Trespj. That is, the hard disk 3022 stores the response time history HIS_R measured by the wireless LAN hardware 301.

  The wireless devices 40 and 50 also have the same configuration as the wireless device 30 shown in FIG.

  FIG. 14 is a diagram for explaining a communication distance determination method in communication distance determination unit 1022 shown in FIG. The communication distance determination unit 1022 reads the total time history HIS_T from the hard disk 1023 and receives the response time history HIS_R from the response time acquisition unit 1021. Then, the communication distance determination unit 1022 associates each total time Ttotalj with each response time Trespj based on the frame sequence number FSN = j. That is, the communication distance determination unit 1022 associates the total time Ttotal1 with the response time Tresp1 based on the frame sequence number FSN = 1, and associates the total time Ttotal2 with the response time Tresp2 based on the frame sequence number FSN = 2. In the same manner, the total time Ttotal is associated with the response time Trespn based on the frame sequence number FSN = n.

  Then, the communication distance determining unit 1022 determines each period (SIFS, Trespn) based on the associated total time and response time pairs [Ttotal1, Tresp1], [Ttotal2, Tresp2], ..., [Ttotal, Trespn]. The communication distance in (PIFS, DIFS) is determined by the method described above.

  [Ttotal1, Tresp1], [Ttotal2, Tresp2],..., [Ttotaln, Trespn] use a free period arbitrarily selected from SIFS, PIFS, and DIFS. Since this is the time measured due to the transmitted and received data DATAj, the communication distance was determined using the average value of n total times Ttotal1 to Ttotal and the average value of n response times Tresp1 to Trespn. Then, the communication distance between the radio | wireless apparatus 10 and the radio | wireless apparatus 30 cannot be determined correctly.

  Therefore, in the present invention, the communication distance is determined by associating the total time measured due to the same data with the response time by the frame sequence number.

  FIGS. 15 and 16 are first and second flowcharts, respectively, for explaining the operation in the third embodiment for determining the communication distance between two wireless devices.

  Steps S31 to S40 shown in FIG. 15 are the same as steps S11 to S20 shown in FIG. In step S36, the wireless device 30 (or wireless devices 40 and 50) stores the measured response time Trespj in the hard disk 3022 in association with the frame sequence number FSN = j. In step S39, the wireless device 10 The measured total time Ttotalj is stored in the hard disk 1023 in association with the frame sequence number FSN = j.

  If it is determined in step S40 that the communication distance is to be determined, the wireless device 10 executes a response time acquisition program, and sends a response time history transmission request to the wireless device 30 (or the wireless devices 40, 40, TCP, IP communication). 50) (step S41).

  Then, the wireless device 30 (or the wireless devices 40 and 50) executes a response time transmission program, receives a response time history transmission request from the wireless device 10 by TCP / IP communication (step S42), and receives the hard disk. The response time history HIS_R is read from 3022, and the response time history HIS_R is transmitted to the wireless device 10 by TCP / IP communication (step S43).

  Thereafter, the wireless device 10 receives the response time history HIS_R from the wireless device 30 (or the wireless devices 40 and 50) by TCP / IP communication (step S44), and reads the total time history HIS_T from the hard disk 1023 (step S44). S45).

  Then, the radio device 10 associates each total time Ttotalj with each response time Trespj based on the frame sequence number FSN and determines a communication distance for each empty period (SIFS, PISF, DIFS) by the method described above ( Step S46).

  Thereby, a series of operations are completed.

  As described above, in the third embodiment, the total time during which data reciprocates between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) using each empty period (SIFS, PISF, DIFS). And the response time in the wireless device 30 (or the wireless devices 40 and 50) are measured by the wireless LAN hardware 101 and 301, respectively, stored in the hard disks 1023 and 3022, respectively, and the TCP / IP communication is performed when determining the communication distance. The response time is transmitted from the wireless device 30 (or the wireless devices 40, 50) to the wireless device 10 to determine the communication distance in each idle period (SIFS, PISF, DIFS).

  That is, the total time and response time are measured by hardware, and the communication distance is determined by software.

  The response time history transmission request and the response time history transmission are performed in accordance with TCP / IP communication, that is, a network layer protocol. The network layer protocol is a protocol for specifying a communication partner.

  The rest is the same as in the first and second embodiments.

  The response time history HIS_R constitutes “first history information”, and the total time history HIS_T constitutes “second history information”.

  Further, the hard disk 3022 constitutes a “first storage device”, and the hard disk 1023 constitutes a “second storage device”.

  Others are the same as in the first embodiment.

[Embodiment 4]
FIG. 17 is a schematic block diagram illustrating a configuration of a wireless device according to the fourth embodiment. In the fourth embodiment, the wireless devices 10, 30, 40, and 50 include the wireless device 12 shown in FIG. The wireless device 12 is the same as the wireless device 10 except that the carrier detector 180 and the controller 210 of the wireless device 10 shown in FIG. 2 are replaced with the carrier detector 180A and the controller 210B, respectively.

  Based on the baseband signal from low-pass filter 150, carrier detector 180A detects the end of data reception, generates signal DETF indicating the end of data reception, and outputs the signal DETF to controller 210B. That is, the carrier detector 180A generates a signal DETS indicating that data reception has started based on the baseband signal from the low-pass filter 150 among the functions of the carrier detector 180 described above, and the generated signal This corresponds to a function in which the function of outputting DETS to the controller 210 is deleted.

  The controller 210B receives the data DATA from the demodulator 160 at the terminal RDA, detects the timing when the data DATA starts to be stably received by a method described later based on the received data DATA, and stabilizes the data DATA. A signal DETS indicating that reception has started is generated and output to the counter 200 from the terminal RDS.

  The controller 210B otherwise performs the same function as the controller 210.

  FIG. 18 is a timing chart of transmission data and reception data in the fourth embodiment. When the wireless devices 10, 30, 40, 50 are composed of the wireless device 12 shown in FIG. 17, the round-trip time during which data reciprocates between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50) will be described.

  The wireless device 10 starts transmitting the data DATT to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20, and ends the transmission of the data DATT at timing t1. Then, the wireless device 30 (or the wireless devices 40 and 50) starts receiving the data DARR from the wireless device 10 via the wireless communication space 20, and the wireless device 30 finishes transmitting the data DATT at the timing t2. (Or wireless devices 40, 50). That is, the time during which data is propagated from the wireless device 10 to the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20 is τ1.

  When the reception of the data DARR from the wireless device 10 is completed, the wireless device 30 (or the wireless devices 40 and 50) measures the response time Tresp by the above-described method, and performs wireless communication at the timing t3 when the measurement of the response time Tresp ends. Transmission of the data DART including the response time Tresp to the wireless device 10 via the space 20 is started. Then, the wireless device 10 starts to receive the data DATR including the response time Tresp from the wireless device 30 (or the wireless devices 40 and 50) via the wireless communication space 20, and the wireless device 30 (or the wireless devices 40 and 50). The transmission start of the data DART is propagated to the radio apparatus 10 at timing t4. Thereafter, the wireless device 10 detects a timing t6 at which data DATR starts to be stably received by a method described later.

  Since the transmission start of the data DART in the wireless device 30 (or the wireless devices 40 and 50) is propagated to the wireless device 10 is the timing t4, the data is transmitted from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device. 10 is the time τ2 from the timing t3 to the timing t4. In the present invention, the data is transmitted from the wireless device 30 (or the wireless devices 40, 50) to the time τ2 from the timing t3 to the timing t4. The time between the timing t5 and the timing t6 at which the wireless device 10 starts to stably receive the data DATR is not the time that is propagated to the wireless device 10, but the data is the wireless device 30 (or the wireless devices 40, 50). ) To the wireless device 10. That is, the time for data to propagate from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10 via the wireless communication space 20 is τ3.

  The reason why the time τ3 from the timing t5 to the timing t6 is set as the time during which data is propagated from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10 will be described later.

  As described above, the counter 200 of the wireless device 10 starts counting the number of components of the clock signal CLK_SEF when receiving the signal DTF at the terminal GTE2, and stops counting the number of components of the clock signal CLK_SEF when receiving the signal DETS at the terminal GTE1. To do. That is, the counter 200 counts the number of components of the clock signal CLK_SEF between the timing t1 and the timing t6.

  Then, by multiplying the count value CNT by the period length of the clock signal CLK_SEF, a total time Ttotal from timing t1 to timing t6 is obtained. As a result, the following equation is established.

Ttotal = τ1 + Tfix + τ3 (2)
Tfix is expressed by the following equation.

Tfix = Tresp + SYNC + SFD (3)
“SYNC” and “SFD” will be described later.

  The response time Tresp is measured by the controller 210B of the wireless device 30 (or the wireless devices 40 and 50) as described above. Since SYNC and SFD are fixed values, the fixed time Tfix (= Tresp + SYNC + SFD) is calculated from the total time Ttotal. When subtracted, τ1 + τ3 is obtained. This τ1 + τ3 is a round-trip propagation time in which data propagates between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50).

  When the round-trip propagation time τ1 + τ3 is obtained, the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) is determined by the method described above.

  Since the response time Tresp is a fixed value in the radio apparatuses 30, 40, and 50, the total time Ttotal becomes longer by the data propagation times τ1 and τ3, as is apparent from FIG.

  FIG. 19 illustrates a method of detecting timing t6 at which the wireless device 10 (transmitter: measuring device) starts to stably receive data DATA from the wireless devices 30, 40, 50 (receiver: device under test). FIG. A packet PKT which is data DATA transmitted / received between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) includes a synchronization signal portion SYNC, a frame start portion SFD, and a frame portion FRM. The synchronization signal part SYNC is provided at the head of the packet PKT. The frame start unit SFD is provided subsequent to the synchronization signal unit SYNC. The frame part FRM is provided subsequent to the frame start part SFD.

  The synchronization signal unit SYNC is a field for arranging data for synchronization when data DATA is transmitted and received between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50). The frame start part SFD is called a start frame delimiter (Start Frame Delimiter) and is a field indicating the start of the frame part FRM. The frame start unit SFD is composed of, for example, an 8-bit pattern of [10101011]. The frame part FRM is a field for arranging data to be transmitted / received.

  The wireless device 10 finishes transmitting the packet PKT having the above-described configuration to the wireless device 30 (or the wireless devices 40 and 50) at the timing t1. Then, the wireless device 10 starts to receive the packet PKT from the wireless device 30 (or the wireless devices 40 and 50) at the timing t4.

  As a result, the wireless device 10 receives the synchronization signal part SYNC and the frame start part SFD of the packet PKT during the period from the timing t4 to the timing t6. During the period when the synchronization signal section SYNC is received, the data received by the wireless device 10 is discontinuous, and the receiving circuit (the amplifier 130, the mixer 140, the demodulator 160, the carrier detector 180A, and the controller 210B) of the wireless device 10 The tuning is not achieved, the gain is unstable, and the synchronization data cannot be demodulated.

  However, as the reception of the synchronization signal unit SYNC is continued, that is, as the timing t6 is approached, the data gradually continues, the gain begins to stabilize, and the synchronization data can be demodulated. At the timing t6 when the reception of the frame start unit SFD ends, the reception circuit (the amplifier 130, the mixer 140, the demodulator 160, the carrier detector 180A, and the controller 210B) of the wireless device 10 is tuned.

  Therefore, in the fourth embodiment, the timing t6 at which the reception of the frame start unit SFD ends is set as a timing at which the wireless device 10 starts to stably receive data from the wireless device 30 (or the wireless devices 40 and 50). .

  Then, the controller 210B of the wireless device 10 receives the data DATA from the demodulator 160 and detects the end position of the frame start unit SFD based on the received data DATA. More specifically, the frame start unit SFD is composed of the 8-bit pattern of [10101011] as described above, and therefore the controller 210B detects [11] which is the last 2 bits of this 8-bit pattern from the data DATA. As a result, the end position of the frame start unit SFD is detected.

  When detecting the end position of the frame start unit SFD, the controller 210B generates a signal DETS and outputs the signal DETS to the counter 200 from the terminal RDS.

  In this way, the receiving circuit (amplifier 130, mixer 140, demodulator 160, carrier detector 180A and controller 210B) of the radio apparatus 10 is not tuned during the period of receiving the synchronization signal part SYNC of the packet PKT, and gain is increased. Is unstable, and the synchronous data cannot be demodulated. When the wireless device 30 (or the wireless devices 40 and 50) is far away from the wireless device 10, the reception of data from the wireless device 30 (or the wireless devices 40 and 50) is a period during which the synchronization signal unit SYNC is received. It becomes even more unstable.

  However, even when the wireless device 30 (or the wireless devices 40 and 50) are far away from the wireless device 10, the reception circuit (amplifier) of the wireless device 10 is detected at timing t6 when the wireless device 10 detects the end position of the frame start unit SFD. 130, mixer 140, demodulator 160, carrier detector 180A and controller 210B) are tuned, so that the wireless device 10 can stably receive data from the wireless device 30 (or the wireless devices 40, 50).

  Accordingly, in the present invention, the time τ3 from the timing t5 to the timing t6 is set as the time for data to propagate from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10.

  When the wireless devices 10, 30, 40, 50 are composed of the wireless device 12 shown in FIG. 17, the operation for determining the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40, 50) has been described above. This is performed according to the flowchart shown in FIG. 6 (or FIG. 11 and FIG. 12 or FIG. 15 and FIG. 16).

  In this case, in step S9 shown in FIG. 6 (or step S19 shown in FIG. 11 and step S29 shown in FIG. 12 or step S39 shown in FIG. 15), the wireless device 10 is the wireless device 30 (or the wireless devices 40 and 50). When the end position of the frame start part SFD included in the data DATA from is detected, the measurement of the total time Ttotal is ended. Therefore, the total time Ttotal represented by the equation (2) can be accurately determined. In other words, even when the wireless device 30 (or the wireless devices 40 and 50) is far away from the wireless device 10, the wireless device 10 starts the reception of data DATA from the wireless device 30 (or the wireless devices 40 and 50). It is possible to accurately determine the propagation time τ3 in which data propagates from the wireless device 30 (or the wireless devices 40 and 50) to the wireless device 10. Then, the total time Ttotal can be accurately determined.

  As a result, the communication distance between the wireless device 10 and the wireless device 30 (or the wireless devices 40 and 50) can be accurately determined.

  Therefore, in the fourth embodiment, the wireless device 10 and the wireless device 30 (the wireless device 10 (or the wireless devices 40 and 50) start receiving data from the wireless device 30 (or the wireless devices 40 and 50) at the timing t6 described above. Alternatively, the method for determining the communication distance between the wireless devices 40 and 50) is applied to any one of the first to third embodiments.

  Thereby, the communication distance described in the first to third embodiments can be determined more accurately.

  In the above description, it has been described that the wireless device 30 (or the wireless devices 40 and 5), which is a device under test, measures its own response time Tresp, but the present invention is not limited to this, and the device under test is not limited thereto. A certain radio apparatus 30 (or radio apparatuses 40 and 5) may measure and hold its own response time Tresp in advance. In this case, when the wireless device 30 (or the wireless devices 40 and 5), which is a device under test, finishes receiving data from the wireless device 10, it waits for its own response time Tresp, and the response time Tresp has elapsed. Later, data including the response time Tresp is transmitted to the wireless device 10.

  The timing t6 corresponds to a timing at which the wireless device 10 (transmitter) starts to stably receive data from the wireless device 30 (or the wireless devices 40 and 50) (receiver).

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a communication system capable of accurately measuring a communication distance between two communication terminals.

1 is a schematic block diagram of a communication system according to Embodiment 1 of the present invention. It is a schematic block diagram which shows the structure of the radio | wireless apparatus shown in FIG. It is a timing chart of transmission data and reception data. It is a conceptual diagram of the packet used when measuring the communication distance between two radio | wireless apparatuses. It is a conceptual diagram which shows the measuring method of the communication distance using the instruction | indication packet and reply packet which are shown in FIG. It is a flowchart for demonstrating the operation | movement which determines the communication distance between a radio | wireless apparatus and a radio | wireless apparatus. It is a figure which shows the relationship between the communication idle time and communication distance which were actually measured. 6 is a schematic block diagram illustrating a configuration of a wireless device in a second embodiment. FIG. 6 is a configuration diagram of a reply packet in Embodiment 2. FIG. FIG. 9 is a conceptual diagram illustrating a method for determining a communication distance in a second embodiment. 10 is a first flowchart for explaining an operation in the second embodiment for determining a communication distance between two wireless devices. 10 is a second flowchart for explaining an operation in the second embodiment for determining a communication distance between two wireless devices. FIG. 11 is a schematic block diagram illustrating a configuration of a wireless device in a third embodiment. It is a figure for demonstrating the determination method of the communication distance in the communication distance determination part shown in FIG. 12 is a first flowchart for explaining an operation in the third embodiment for determining a communication distance between two wireless devices. 12 is a second flowchart for explaining an operation in the third embodiment for determining a communication distance between two wireless devices. FIG. 10 is a schematic block diagram illustrating a configuration of a wireless device in a fourth embodiment. 10 is a timing chart of transmission data and reception data in the fourth embodiment. It is a figure for demonstrating the method to detect the timing which a radio | wireless apparatus (transmitter: measuring machine) begins to receive the data from a radio | wireless apparatus (receiver: device under test) stably.

Explanation of symbols

  10 to 12, 30, 40, 50 Wireless device, 20 Wireless communication space, 31, 41 Frame control unit, 32, 42 Length unit, 33, 43 Reception side address unit, 34 Transmission side address unit, 35, 45 Frame check Sequence unit, 44, 44A Response time data unit, 100 communication system, 101, 301 wireless LAN hardware, 102, 302 personal computer, 110 antenna, 120, 240 selector, 121, 122, 241, 242 terminal, 123, 243 Switch, 130, 290 Amplifier, 140, 280 Mixer, 150, 270 Low pass filter, 160 Demodulator, 170 Clock adjuster, 180, 180A Carrier detector, 190 A / D converter, 200 Counter, 210, 210A, 210B Controller 211 timer, 220 crystal oscillator, 230 clock generator, 250 1 / N divider, 260 modulator, 440 number part, 441 to 44n data part, 1021 response time acquisition part, 1022 communication distance determination part, 1023, 3022 hard disk , 3021 Response time transmission unit.

Claims (9)

A communication system capable of measuring a communication distance between two communication terminals arranged in a wireless communication space,
A transmitter for transmitting data via the wireless communication space;
A receiver that receives data from the transmitter via the wireless communication space and transmits data for a response to the received data to the transmitter via the wireless communication space;
The transmitter and the receiver transmit and receive the data in synchronization with a reference clock,
The transmitter measures a total time between a first timing for completing the transmission of the data to the receiver and a second timing for starting reception of the data from the receiver. A communication system that determines a communication distance to the receiver based on the total time measured and the response time of the receiver received from the receiver. The receiver measures the response time according to the completion of reception of the data from the transmitter, and transmits the response time to the transmitter after the measured response time has elapsed,
The transmitter subtracts the received response time from the total time to calculate a round trip time for the data to reciprocate with the receiver, and communicates with the receiver based on the calculated round trip time. The communication system according to claim 1, wherein the distance is determined. The transmitter transmits an instruction packet instructing measurement of the response time to the receiver, receives a reply packet including the response time from the receiver, and acquires the response time.
The communication according to claim 2, wherein the receiver measures the response time according to the instruction packet, and transmits the reply packet including the response time to the transmitter after the measured response time has elapsed. system. The receiver measures the response time every time the data is received from the transmitter, stores a plurality of response times, and receives an instruction packet instructing transmission of the response time from the transmitter, Sending a reply packet including a plurality of stored response times to the transmitter;
The transmitter transmits the instruction packet to the receiver at an arbitrary timing, receives the reply packet from the receiver, acquires the plurality of response times, and averages the acquired plurality of response times The communication system according to claim 2, wherein a communication distance to the receiver is determined by subtracting an average response time from the total time. The receiver corresponds to a plurality of data transmitted from the transmitter by using a plurality of idle periods of the wireless communication space by measuring the response time each time the data is received from the transmitter. When a plurality of response times are measured, first history information including the measured response times is stored in the first storage device, and a transmission request for requesting transmission of the response times is received from the transmitter. , Obtaining the first history information from the first storage device and transmitting it to the transmitter;
The transmitter measures a plurality of total times corresponding to the plurality of data by measuring the total time each time each data is transmitted to the receiver, and includes a plurality of the total times measured. The history information is stored in the second storage device, the transmission request is transmitted to the receiver, the first history information is received from the receiver, and the plurality of response times are acquired. And determining a plurality of communication distances corresponding to the plurality of data based on the plurality of response times and a plurality of total times included in the second history information acquired from the second storage device. 2. The communication system according to 2. The first history information is
A plurality of sequence numbers assigned to the plurality of data;
The plurality of response times associated with the plurality of sequence numbers,
The second history information is
The plurality of sequence numbers;
The plurality of total times associated with the plurality of sequence numbers,
When the transmitter receives the first history information from the receiver, the transmitter acquires the second history information from the second storage device, and a plurality of sequence numbers included in the acquired second history information. The communication system according to claim 5, wherein a plurality of communication distances corresponding to the plurality of data are determined by associating the plurality of total times with the plurality of response times based on the information. The receiver receives the transmission request from the transmitter according to a protocol for specifying a communication partner among a plurality of protocols used for communication with the transmitter, and transmits the first history information to the transmitter. Send
7. The communication according to claim 5, wherein the transmitter transmits the transmission request to the receiver according to a protocol that specifies a counterpart of the communication, and receives the first history information from the receiver. 8. system. The second timing is a timing at which the transmitter starts to stably receive data from the receiver,
The communication system according to any one of claims 1 to 7, wherein the transmitter determines the communication distance based on a predetermined time including the response time and the total time.   The communication system according to claim 8, wherein the second timing is a start frame delimiter.

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