JP2014220561A - Radio communications system, radio terminal device, and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communications system capable of increasing reliability of data reception from a terminal device and saving power consumption of the terminal device.SOLUTION: A radio communications system includes a radio communication device for returning a response including own identification information when a trigger signal is received, and a radio terminal device for transmitting a trigger signal, and for transmitting notice information representing own device existence based on identification information when the identification signal is received from the radio communication device. The radio terminal device includes speed measurement means for measuring own moving speed, and period setting means for setting a transmission period of a trigger signal so as to be a predetermined value on the basis of a communicable distance of the radio terminal device and the moving speed measured by the speed measurement means.

Description

  The present invention relates to a wireless communication system, a wireless terminal device, and a wireless communication method.

  Conventionally, there is a wireless communication system in which a roadside device arranged on the road side transmits a request signal, and a terminal device that receives the request signal wirelessly transmits data in response to the request. As an application example of such a wireless communication system, there is a local security system for monitoring a child (for example, see Patent Document 1). The local security system includes a name tag with a wireless tag, a security light, an access point, a security bulletin board, a monitoring terminal, a reception device, a gate sensor, and a network. The name tag with a wireless tag is a name tag worn by a child who goes to and from school, and the location of the child can be monitored from the reception device by incorporating the wireless tag into the name tag. The security light includes a wireless LAN device that communicates with a name tag with a wireless tag, an access point, and another security light. The name tag and the security light with the wireless tag communicate with others by ad hoc communication. The accepting device monitors the tag ID according to the conditions set by the monitoring terminal. As a result, costs associated with installation and maintenance of equipment can be reduced and monitoring can be performed with a corresponding degree of freedom.

JP 2007-042009 A

  However, in the conventional wireless communication system, data transmission from the terminal device is limited to when the request signal is received. Therefore, depending on the positional relationship with the receiving device and the radio wave condition when data transmission is performed from the terminal device. However, there is a problem in that the data on the receiving device cannot be received normally from the terminal device. In order to solve such a problem, the terminal device may continuously perform data transmission, but this configuration cannot be adopted when there is a limit on the power consumption of the terminal device. There's a problem.

  The present invention has been made in view of such circumstances, and improves the reliability with which data from a wireless terminal device can be received, and also saves power consumption in the wireless terminal device. It is an object to provide a terminal device and a wireless communication method.

  The present invention provides a wireless communication device that returns a response including its own identification information when receiving a trigger signal, and transmits the trigger signal and receives the identification information from the wireless communication device. And a wireless terminal device that transmits broadcast information indicating the presence of the wireless communication device, the wireless terminal device comprising: a speed measuring unit that measures its own moving speed; and communication between the wireless communication device and the wireless communication device. Period setting means is provided for setting the transmission period of the trigger signal to be a predetermined value from the possible distance and the moving speed measured by the speed measuring means.

  In the present invention, the wireless communication device transmits its own communicable distance to the wireless terminal device, and the period setting unit uses the communicable distance transmitted from the wireless communication device to generate the trigger. A signal transmission cycle is set.

  The present invention is characterized in that the wireless communication device estimates a moving speed of the wireless terminal device from the communicable distance and a transmission cycle of the trigger signal.

  The present invention is characterized in that the wireless communication device estimates a received power value and a slope of the received power value, and estimates an angular relationship at a zone edge of the wireless terminal device from the estimated value of the slope.

  The present invention provides a wireless communication device that returns a response including its own identification information when receiving a trigger signal, and transmits the trigger signal and receives the identification information from the wireless communication device. , A wireless terminal device used in a wireless communication system including a wireless terminal device that transmits broadcast information indicating the presence of the wireless communication device, and communication between the wireless communication device and a speed measuring unit that measures its own moving speed Period setting means is provided for setting a transmission period of the trigger signal to be a predetermined value from the distance and the moving speed measured by the speed measuring means.

  The present invention provides a wireless communication device that returns a response including its own identification information when receiving a trigger signal, and transmits the trigger signal and receives the identification information from the wireless communication device. Is a wireless communication method performed by a wireless communication system including a wireless terminal device that transmits broadcast information indicating the presence of the wireless terminal device, wherein the wireless terminal device measures its own moving speed; and The wireless terminal device has a cycle setting step for setting the transmission cycle of the trigger signal to be a predetermined value from the communicable distance of the wireless communication device and the moving speed measured by the speed measuring step. It is characterized by.

  According to the present invention, it is possible to improve the reliability with which data from a wireless terminal device can be received and to save power consumption in the wireless terminal device.

It is a block diagram which shows the structure of one Embodiment of this invention. It is a flowchart which shows operation | movement of the radio | wireless communication apparatuses 20-1 to 3 shown in FIG. 3 is a flowchart illustrating an operation of the wireless terminal device 30 illustrated in FIG. 1. 3 is a flowchart illustrating an operation of the wireless terminal device 40 illustrated in FIG. 1. It is explanatory drawing which shows the effect of this invention.

  Hereinafter, a wireless communication apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. The device configuration shown in FIG. 1 shows an example in which a wireless communication device is used as a system for informing the surroundings of the presence of a moving object. In FIG. 1, reference numerals 10-1 to 3 are roadside devices installed side by side near the intersection of roads. Reference numerals 20-1 to 20-3 are provided in the roadside devices 10-1 to 10-3, respectively, and a wireless zone is formed by each wireless communication device. Reference numeral 30 denotes a wireless terminal device that is carried by a person or attached to a moving body such as a bicycle (hereinafter, a person or a bicycle is referred to as a moving body). The wireless terminal 30 includes two types of wireless tags having different frequencies. Reference numeral 40 denotes a wireless terminal device mounted on an automobile or the like, and is composed of one type of wireless tag.

  FIG. 1 shows a pedestrian or bicycle carrying the wireless terminal device 30 entering the T-shaped road. When the speed of a moving body such as a pedestrian is slow, an HF band trigger signal is transmitted at a slow cycle. Since the zone diameter is determined by the initial response from the wireless communication devices 20-1 to 20-3, the optimum trigger signal cycle is set accordingly. The wireless communication devices 20-1 to 20-3 receiving the trigger signal estimate the moving speed from the cycle, and when located near the communication device 20-1 or the communication device 20-2, the communication terminal is in the UHF band. The transmission request for the notification signal is not notified, and the transmission request is notified for the first time when the communication device 20-3 is located. When the vehicle equipped with the UHF band wireless terminal device 40 is near the T-junction, a notification signal is received to notify the presence of a pedestrian in advance.

  On the other hand, in the case of a bicycle with a fast moving speed, the trigger signal is transmitted at an early cycle at the beginning, but the zone diameter is determined by the initial response from the communication device, and the optimum trigger signal is determined accordingly. The period is set. In addition, the communication device estimates that the speed of the moving body is fast by receiving a trigger signal with a fast cycle, and notifies at a position (for example, the position of the wireless communication device 20-2) with some margin not near the T-junction. Signal transmission request is notified. As a result, the automobile near the T-shaped road can know the moving body having a high intrusion speed in advance than the slow moving body.

  Next, the configuration of radio communication apparatus 20-1 shown in FIG. 1 will be described. Since the configurations of the wireless communication devices 20-2 and 20-3 are the same as the configuration of the wireless communication device 20-1, detailed description thereof is omitted. In FIG. 1, the code | symbol 21 is an antenna with which the radio | wireless communication apparatus 20-1 is equipped. Reference numeral 22 denotes a switch for switching the antenna 21 between reception and transmission. Reference numeral 23 denotes a receiving unit that receives a signal via the antenna 21. Reference numeral 24 denotes a transmission unit that transmits a signal via the antenna 21. Reference numeral 25 denotes a control unit that controls the overall operation of the wireless communication device 20-1. Reference numeral 26 denotes a storage unit that stores information. The wireless communication device 20-1 is configured as a communication module capable of transmitting HF band radio waves used for extremely short-distance communication. The storage unit 26 stores identification information for identifying each communication device or requesting notification signal transmission, communicable distance information of a wireless zone, and the like, and transmits the response as a trigger signal response from the wireless terminal device.

  Next, the configuration of the wireless terminal device 30 shown in FIG. 1 will be described. In FIG. 1, reference numeral 31 denotes an antenna provided in the wireless terminal device 30. Reference numeral 32 denotes a switch for switching the antenna 31 between reception and transmission. Reference numeral 33 denotes a receiving unit that receives a signal via the antenna 31. Reference numeral 34 denotes a transmission unit that transmits a signal via the antenna 31. Reference numeral 35 denotes a speedometer that measures the speed of the wireless terminal device 30 itself. Reference numeral 36 denotes a control unit that performs overall control of the operation of the wireless terminal device 30. Reference numeral 37 denotes a storage unit that stores information. The code | symbol 38 is a transmission part which transmits the information for alert | reporting presence of a moving body to the circumference | surroundings. The wireless terminal device 30 includes an HF band transmission / reception unit (reception unit 33, transmission unit 34) used for communication over an extremely short distance, and a UHF band transmission unit 38 having a communication distance of several tens of meters. Sets the period of the transmission trigger signal.

  Next, the configuration of the wireless terminal device 40 shown in FIG. 1 will be described. In FIG. 1, reference numeral 41 denotes an antenna provided in the wireless terminal device 40. Reference numeral 42 denotes a receiving unit that receives a UHF band signal having a communication distance of several tens of meters through the antenna 41. Reference numeral 43 denotes a control unit that performs overall control of the operation of the wireless terminal device 40. Reference numeral 44 denotes an output unit that outputs an alarm or the like. The wireless terminal device 40 receives a UHF band notification signal transmitted from the wireless terminal device 30 carried by the mobile body, and outputs information indicating that the mobile body is present in the vicinity, thereby driving the driver. Call attention to.

  Next, the operation of the wireless communication device 20-1 shown in FIG. 1 will be described with reference to FIG. Since the processing operations of the wireless communication devices 20-2 and 20-3 illustrated in FIG. 1 are the same as the processing operations of the wireless communication device 20-1, detailed description thereof is omitted. FIG. 2 is a flowchart showing the operation of the wireless communication apparatus 20-1 shown in FIG. First, the control unit 25 of the wireless communication device 20-1 waits for reception until receiving a trigger signal from the wireless terminal device 30 carried by the mobile body (step S1), and whether or not the trigger signal has been received. Is determined (step S2). As a result of this determination, if no trigger signal is received, the reception standby is continued. On the other hand, when the trigger signal is received from the wireless terminal device 30, the control unit 25 switches the switch 22 for transmission, and transmits its own identification information and the communicable distance r via the transmission unit 24 (step S3). ).

  Next, the wireless terminal device 30 that has received the communicable distance r satisfies the transmission cycle N in order to satisfy a preset number of transmissions (for example, M times) while traveling in the wireless zone at the speed V. Is set to M × V / (2r × sin (θ)) and a trigger signal is transmitted (where 2r × sin (θ) is a communicable distance along the traveling direction of the moving body). Here, as the value of θ, a value estimated from the inclination of the received power or a value assuming that the moving body passes near the center of the road is used.

  On the other hand, the control unit 25 of the wireless communication apparatus 20-1 assumes a cycle Navg = M × Vavg / (2r × sin (θ)) that is M times when the moving body moves at the speed Vavg. Accordingly, the speed of the moving body is estimated from the ratio of transmission cycles N / Navg = V / Vavg (step S4). Then, the wireless communication devices 20-2, 20-2, 20B, 20B, 20B, 20C, and 20C, each of which has a lower threshold for the moving speed as the wireless communication devices (wireless communication devices 20-2 and 20-3 in the example shown in FIG. Based on the risk information stored in the storage unit 26 of 20-3, it is determined whether or not the wireless terminal device 30 should transmit the notification information in order to notify the surrounding wireless terminal device 40 (automobile or the like) of the presence of the moving body. (Step S5). As a result of the determination, if it is not necessary to transmit, the process returns to step S1 and continues. On the other hand, when it determines with having transmitted, the control part 25 transmits a alerting | reporting signal transmission request | requirement via the transmission part 24 (step S6), returns to step S1, and continues a process.

Next, the operation of the wireless terminal device 30 shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a flowchart showing the operation of the wireless terminal device 30 shown in FIG. Based on the velocity V of the moving body output from the speedometer 35, the control unit 36 uses the communicable distance r _S of the standard wireless zone, and the number of transmissions in advance while traveling in the wireless zone (for example, M In order to satisfy (times), the initial value of the trigger signal transmission cycle is determined to be M × V / (2r _S × sin (θ)) and transmitted (step S11). And the control part 36 determines whether the response from the radio | wireless communication apparatus 20-1-3 installed by the roadside was received (step S12), and when there is no response, it returns to step S11, and initial value A trigger signal is transmitted at a period of.

  On the other hand, when the responses from the wireless communication devices 20-1 to 20-3 are received, the control unit 36 acquires the identification information and the communicable distance r from the received signal received via the receiving unit 33 (step S13). The control unit 36 resets the transmission trigger period based on the communicable distance information based on the identification information, the directly communicable distance information acquired directly, and the speed input from the speedometer, and transmits a trigger signal (step S14). Further, it is determined whether or not the notification information transmission request is received from the wireless communication devices 20-1 to 20-3 (step S15). If the notification information transmission request is not received from the wireless communication devices 20-1 to 20-3, step S12 is performed. Return to and continue processing.

  On the other hand, when the notification information transmission request is received from the wireless communication devices 20-1 to 20-1, the control unit 36 notifies the surrounding automobile that the moving body is located near the intersection, via the transmission unit 38. Broadcast information is transmitted in the UHF band (step S16), the process returns to step S12, and the process is continued. Note that the broadcast information transmission request may be, for example, a certain set speed information, and determine whether the wireless terminal device 30 that has received the information has a speed that is equal to or higher than a threshold value to determine whether a broadcast signal is transmitted. .

  Next, the operation of the wireless terminal device 40 shown in FIG. 1 will be described with reference to FIG. FIG. 4 is a flowchart showing the operation of the wireless terminal device 40 shown in FIG. First, the control unit 43 waits for reception until receiving notification information from the wireless terminal device 30 carried by the mobile body (step S21), and determines whether the notification information has been received (step S22). . As a result of this determination, if no broadcast information is received, reception standby is continued. On the other hand, when the notification is received from the wireless terminal device 30 via the receiving unit 42, the control unit 43 outputs the notification information to the output unit 44 (step S23). At this time, the output unit 44 outputs alarm information to an alarm device or the like provided in the automobile, thereby outputting an alarm within the automobile.

  A plurality of wireless communication devices are installed at predetermined intervals along the moving direction of the moving body, and each wireless communication device receives a trigger signal transmitted from a wireless terminal device installed on the moving body, thereby identifying its own device In the system that informs the surroundings of the presence of the moving body in accordance with the identification signal received by the wireless terminal device, the wireless terminal device measures the moving speed of the own device, the own device and each wireless communication device The trigger signal transmission cycle is set so that the trigger signal is transmitted a predetermined number of times to each wireless communication device based on the communicable distance.

  As a result, the wireless communication device can estimate the moving speed of the wireless terminal device, can notify the wireless terminal device of appropriate transmission timing of the notification signal, and transmit an excessive notification signal from the wireless terminal device. The power consumption of the wireless terminal device can be reduced.

  In the above description, an example in which an HF band signal is used for “ultra-short-distance communication” and an UHF band signal is used for “several tens of meters” is an example. The frequency band of signals that can be used in each communication is not limited to this example.

  FIG. 5 is an explanatory diagram showing the effect of the present invention. As described above, in the prior art, radio waves are transmitted at a constant cycle regardless of whether or not there is a wireless terminal device in the communicable region, so that it is difficult to reduce power consumption and the transmission cycle is a wireless terminal device. If the speed is not properly set, there is a problem that the wireless terminal device passes through the communicable region without receiving the trigger signal.

  On the other hand, in the wireless communication system according to the present invention, since standby is performed in a normal reception state, it is possible to reduce power consumption. Further, since the wireless terminal device controls the trigger cycle according to its own moving speed, it is possible to prevent the wireless terminal device from passing through the communicable area before responding. Furthermore, it can be estimated from the transmission cycle of the wireless communication device that the moving speed of the wireless terminal device is V1> V2.

  As described above, the wireless communication apparatus is normally in a standby state for reception, and it is possible to reduce power consumption by transmitting only when the trigger signal of the wireless terminal apparatus is received. In addition, the wireless communication device estimates the moving speed of the wireless terminal device and notifies the terminal device of appropriate transmission timing of the notification signal in consideration of the installation location, thereby suppressing excessive transmission of the notification signal. As a result, the power consumption of the wireless terminal device can be reduced. Furthermore, since the wireless terminal device can set an appropriate transmission period of the trigger signal from its own moving speed and the communicable distance notified from the roadside wireless communication device, data can be received normally depending on the positional relationship between the devices and the radio wave condition. The problem of not being able to be solved can be solved.

  The wireless communication devices 20-1 to 20-3, the wireless terminal device 30, and the wireless terminal device 40 in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be realized using hardware such as PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

  As mentioned above, although embodiment of this invention has been described with reference to drawings, the said embodiment is only the illustration of this invention, and it is clear that this invention is not limited to the said embodiment. is there. Accordingly, additions, omissions, substitutions, and other changes of the components may be made without departing from the technical idea and scope of the present invention.

  When a request signal transmitted from a roadside device arranged on a road is received, in a configuration including a terminal device that wirelessly transmits data corresponding to the request signal, the reliability of receiving data from the terminal device is improved. Therefore, the present invention can be applied to applications in which it is essential to save power consumption in the terminal device.

  20-1 to 3... Wireless communication device, 21 to antenna, 22 to switch, 23 to receiving unit, 24 to transmitting unit, 25 to controlling unit, 26 to storing. , 30 ... wireless terminal device, 31 ... antenna, 32 ... switch, 33 ... receiving unit, 34 ... transmitting unit, 35 ... speedometer, 36 ... control unit, 37: storage unit, 38: transmission unit, 39: antenna, 40 ... wireless terminal device, 41 ... antenna, 42 ... reception unit, 43 ... control unit, 44 ..Output section

Claims (6)

A wireless communication device that returns a response including its own identification information when it receives the trigger signal, and transmits the trigger signal and receives the identification information from the wireless communication device. A wireless communication system including a wireless terminal device that transmits broadcast information indicating the presence of
The wireless terminal device
A speed measuring means for measuring the moving speed of the self;
A period setting unit configured to set a transmission period of the trigger signal to be a predetermined value from a communicable distance of the wireless communication device and the moving speed measured by the speed measuring unit; Wireless communication system. The wireless communication device transmits its communicable distance to the wireless terminal device,
The wireless communication system according to claim 1, wherein the cycle setting unit sets a transmission cycle of the trigger signal using the communicable distance transmitted from the wireless communication device.   The wireless communication system according to claim 1, wherein the wireless communication device estimates a moving speed of the wireless terminal device from the communicable distance and a transmission cycle of the trigger signal.   4. The wireless communication device according to claim 1, wherein the wireless communication device estimates a received power value and a slope of the received power value, and estimates an angular relationship at a zone end of the wireless terminal device from the estimated value of the slope. A wireless communication system according to claim 1. A wireless communication device that returns a response including its own identification information when it receives the trigger signal, and transmits the trigger signal and receives the identification information from the wireless communication device. A wireless terminal device used in a wireless communication system including a wireless terminal device that transmits broadcast information indicating the presence of
A speed measuring means for measuring the moving speed of the self;
A period setting unit configured to set a transmission period of the trigger signal to be a predetermined value from a communicable distance of the wireless communication device and the moving speed measured by the speed measuring unit; Wireless terminal device. A wireless communication device that returns a response including its own identification information when it receives the trigger signal, and transmits the trigger signal and receives the identification information from the wireless communication device. A wireless communication method performed by a wireless communication system including a wireless terminal device that transmits broadcast information indicating the presence of
A speed measuring step in which the wireless terminal device measures its moving speed;
The wireless terminal device has a cycle setting step for setting the transmission cycle of the trigger signal to be a predetermined value from the communicable distance of the wireless communication device and the moving speed measured by the speed measuring step. A wireless communication method.

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