JP2012065232A - Radio tag system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio tag system which can perform communication confirmation processing performed to a radio tag reader from a radio tag with a more adequate interval, and can save power of the radio tag more effectively.SOLUTION: A radio tag system 1 comprises: a radio tag 50 having a built-in battery; a radio tag reader 10 reading out the radio tag 50 within a first communication area AR1; and a reader side base station 80a performing radio LAN communication with the radio tag 50 within a second communication area AR2 which is wider than the first communication area AR1 constructed by the radio tag reader 10 and includes the periphery of the first communication area AR1. Radio tag communication means provided in the radio tag 50 changes an interval of communication confirmation processing for the radio tag reader 10 according to the state of radio LAN communication between radio LAN communication means and the reader side base station 80a.

Description

  The present invention relates to a wireless tag system.

  Conventionally, an active tag equipped with a built-in battery has been provided. This type of active tag is supplied with power from the battery mounted in the tag and can emit radio waves spontaneously, so it generally has the advantage of ensuring a wider communication area compared to passive tags. Yes, it is widely used for various purposes by taking advantage of such merits. Note that, as an example of a wireless tag system using an active tag, for example, Patent Document 1 is provided.

  In the technique of Patent Document 1, the mobile terminal detects the current position, refers to the past received power level of the detected current position in the history information, and depends on the obtained past received power level. This controls the detection operation. By doing in this way, reception detection operation can be performed more appropriately and it becomes easy to achieve power saving of a portable terminal.

JP 2009-231868 A

  By the way, in the wireless tag system as described above, not only power saving of the wireless tag reader but also power saving of the wireless tag is required. In particular, wireless tags equipped with a built-in battery are required to further reduce power consumption from the viewpoint of battery life and merchantability, especially when building a system that constantly monitors active tags. There is a great demand for reducing power consumption.

  For example, in a system in which a wireless tag reader is placed at a predetermined location and an active tag is monitored, the active tag periodically transmits a predetermined command to the wireless tag reader, and the wireless tag reader returns a response thereto. One that establishes a communication link is conceivable. In such a system, if the frequency of transmission performed by the active tag (for example, the frequency of command transmission) is too large, there is a problem that power consumption increases and the life of the built-in battery is shortened. Then, there is a problem that it is difficult for the wireless tag reader to detect the active tag.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to perform communication confirmation processing from a wireless tag to a wireless tag reader at a more appropriate interval. An object of the present invention is to provide a wireless tag system that can more effectively reduce power consumption of a tag.

  The invention of claim 1 is a wireless tag having a built-in battery, a wireless tag reader that reads the wireless tag in a predetermined first communication area, and wider than the first communication area configured by the wireless tag reader, and A reader-side base station that performs wireless LAN communication with the wireless tag in a second communication area including the periphery of the first communication area, and the wireless tag periodically performs communication confirmation processing on the wireless tag reader Wireless tag communication means for performing wireless LAN communication with the reader-side base station, and the wireless tag communication means is provided between the wireless LAN communication means and the reader-side base station. The communication confirmation processing interval for the wireless tag reader is changed in accordance with the state of wireless LAN communication.

  A second aspect of the present invention is the wireless tag system according to the first aspect, wherein the wireless tag communication means cannot receive a response from the wireless tag reader and the wireless LAN communication means is the reader-side base. The communication confirmation processing interval when communication with a station is possible is set shorter than the communication confirmation processing interval when a response can be received from the wireless tag reader.

  The invention of claim 3 is the wireless tag system according to claim 1 or 2, wherein the wireless tag communication means cannot receive a response from the wireless tag reader, and When the wireless LAN communication means cannot communicate with the reader-side base station, the communication confirmation process is suspended.

  A fourth aspect of the present invention is the wireless tag system according to any one of the first to third aspects, wherein the wireless LAN communication unit is in a state in which the wireless tag and the wireless tag reader can communicate with each other. At some time, wireless LAN communication with the reader-side base station is suspended.

  A fifth aspect of the present invention is the wireless tag system according to any one of the first to fourth aspects, wherein the wireless LAN communication means cannot receive a confirmation signal from the reader-side base station for a certain period. When this happens, wireless LAN communication performed with the reader-side base station is suspended, and wireless LAN communication processing with the outside is started when a predetermined start condition is satisfied.

  A sixth aspect of the present invention is the wireless tag system according to any one of the first to fifth aspects, further disposed in a predetermined third communication area that does not overlap the first communication area. An external base station capable of wireless LAN communication with the wireless tag, wherein the wireless LAN communication means is in a state of wireless LAN communication performed with the reader-side base station, and the external base station The interval of the radio wave reception processing in the wireless LAN communication is changed according to at least one of the states of the wireless LAN communication performed between the wireless LAN communication and the wireless LAN communication.

  A seventh aspect of the present invention is the wireless tag system according to the sixth aspect, wherein the wireless LAN communication means sets a radio wave reception processing interval when wireless LAN communication is possible with the reader-side base station. A predetermined first interval is set, and an interval of radio wave reception processing when wireless LAN communication is possible with the external base station is set to a second interval longer than the first interval.

  The invention according to claim 8 is the radio tag system according to claim 7, wherein the radio LAN communication means is in a state in which radio LAN communication is possible between the external base station and the radio base station. Is set to the second interval, and the radio wave reception interval is set to a third interval shorter than the second interval when wireless LAN communication with the external base station is changed from a possible state to an impossible state. is doing.

The invention according to claim 1 is a wireless communication device including a built-in battery, a wireless tag reader that reads a wireless tag within a predetermined first communication area, and a first communication area that is wider than a first communication area that includes the wireless tag reader. And a reader-side base station that performs wireless LAN communication with the wireless tag in the second communication area including the surrounding area. The wireless tag is provided with wireless tag communication means for periodically performing communication confirmation processing with respect to the wireless tag reader, and wireless LAN communication means for performing wireless LAN communication with the reader-side base station. The means changes the communication confirmation processing interval for the wireless tag reader in accordance with the state of wireless LAN communication between the wireless LAN communication means and the reader-side base station.
In this case, even when the wireless tag is out of the communication area (first communication area) of the wireless tag reader, wireless LAN communication with the reader-side base station is possible (that is, close to the wireless tag reader communication area). In this case, the communication confirmation processing interval for the wireless tag reader can be easily adjusted to an interval suitable for the position. In particular, it becomes easier to save power compared to a configuration in which the interval of communication confirmation processing is set to be short regardless of the proximity of the wireless tag reader to the communication area.

  In the invention of claim 2, the wireless tag communication means sets the interval of the communication confirmation processing when the response from the wireless tag reader is unreceivable and the wireless LAN communication means can communicate with the reader-side base station from the wireless tag reader. It is set shorter than the interval of the communication confirmation process when the response can be received. In this way, when the wireless tag exists near the first communication area outside the communication area (first communication area) of the wireless tag reader, the communication confirmation process is performed more frequently than when the wireless tag exists in the first communication area. Will be performed. Therefore, the wireless tag reader can detect earlier the wireless tag that is about to enter the first communication area from the vicinity of the first communication area.

  In the invention of claim 3, the wireless tag communication means pauses the communication confirmation process when the response from the wireless tag reader cannot be received and the wireless LAN communication means cannot communicate with the reader-side base station. . According to this configuration, when the wireless tag moves away from the communication range of the wireless tag reader and the possibility of communication decreases, power saving can be effectively achieved.

  According to a fourth aspect of the present invention, the wireless LAN communication means suspends wireless LAN communication performed with the reader-side base station when the wireless tag and the wireless tag reader are in a communicable state. According to this configuration, when the wireless tag already exists in the communication area of the wireless tag reader and it is not necessary to grasp the positional relationship by wireless LAN communication, the wireless LAN is suspended to appropriately save power. Can be achieved.

In the invention of claim 5, the wireless LAN communication means pauses the wireless LAN communication performed with the reader-side base station when the confirmation signal from the reader-side base station becomes unreceivable for a certain period, When the start condition is satisfied, the wireless LAN communication process with the outside is started.
According to this configuration, a confirmation signal from the reader-side base station cannot be received for a certain period on the wireless tag side, and there is a high possibility that the wireless tag has moved away from the communication area of the reader-side base station (that is, the wireless tag When the possibility of performing wireless LAN communication with the reader-side base station becomes low), it is possible to appropriately save power by suspending the wireless LAN communication.

According to a sixth aspect of the present invention, an external base station capable of wireless LAN communication with a wireless tag arranged in a predetermined third communication area that does not overlap with the first communication area is provided. The wireless tag communication means of the wireless tag is at least one of a state of wireless LAN communication performed with the reader-side base station and a state of wireless LAN communication performed with the external base station. The interval of radio wave reception processing in wireless LAN communication is changed according to the state.
In this way, the wireless tag is in a state where it can communicate with a reader-side base station close to the wireless tag reader, or the wireless tag is in a state where it can communicate with an external base station far from the wireless tag reader, or which base Whether the wireless tag can communicate with the station can be accurately grasped on the wireless tag side, and the interval of radio wave reception processing performed by the wireless tag can be appropriately changed according to the position of the wireless tag.

In the invention of claim 7, the wireless LAN communication means of the wireless tag sets the interval of radio wave reception processing when wireless LAN communication is possible with the reader-side base station to a predetermined first interval, and the external base station The interval of radio wave reception processing when wireless LAN communication is possible is set to a second interval longer than the first interval.
In this case, when communication is possible with an external base station in which a communication area farther from the communication area (first communication area) of the wireless tag reader is set (that is, the wireless tag is separated from the communication area of the wireless tag reader, When there is a low possibility that communication with the wireless tag reader will be immediately performed), the interval between radio wave reception processes can be set relatively long. Therefore, it is unlikely that communication with the wireless tag reader is performed, and it is possible to appropriately grasp the state in which the result of wireless LAN communication hardly affects the detection of the wireless tag reader, and to effectively save power.

The invention of claim 8 sets the interval of radio wave reception processing when the wireless LAN communication means is in a state capable of wireless LAN communication with an external base station to the second interval, and with the external base station, When the wireless LAN communication is changed from a possible state to an impossible state, the radio wave reception interval is set to a third interval shorter than the second interval.
According to this configuration, when the wireless tag is separated from the communication area (third communication area) of the external base station and may approach the wireless tag reader side, the frequency of radio wave communication radio wave reception processing can be increased. . Therefore, when the wireless tag reaches the communication area of the reader-side base station, wireless LAN communication can be performed quickly.

FIG. 1 is an explanatory diagram schematically illustrating the wireless tag system according to the first embodiment of the present invention. FIG. 2 is a block diagram schematically illustrating an electrical configuration of a wireless tag reader used in the wireless tag system of FIG. FIG. 3 is a block diagram schematically illustrating an electrical configuration of a wireless tag used in the wireless tag system of FIG. FIG. 4A is a block diagram schematically illustrating an electrical configuration of a reader-side base station used in the wireless tag system of FIG. FIG. 4B is a block diagram schematically illustrating an electrical configuration of an external base station used in the wireless tag system of FIG. FIG. 5 is a flowchart illustrating the flow of the RFID tag communication process (RFID communication process) performed by operating the tag communication unit (transmission unit and reception unit). FIG. 6 is a flowchart illustrating the flow of wireless LAN communication processing performed by operating the wireless LAN communication unit. FIG. 7 is a timing chart illustrating the timing of the communication confirmation process by the wireless tag communication process and the radio wave reception timing by the wireless LAN communication process. FIG. 8A is an explanatory diagram conceptually illustrating a frame configuration of transmission data transmitted from the wireless tag to the wireless tag reader. FIG. 8B is an ACK (acknowledgment) transmitted from the wireless tag reader to the wireless tag. FIG. 3 is an explanatory diagram conceptually illustrating the frame configuration of FIG.

[First embodiment]
Hereinafter, a first embodiment in which a wireless tag system of the present invention is embodied will be described with reference to the drawings.
First, with reference to FIGS. 1 to 4 and the like, a hardware configuration of each element constituting the wireless tag system 1 according to the present embodiment will be described.
FIG. 1 is an explanatory diagram schematically illustrating the wireless tag system according to the first embodiment of the present invention. FIG. 2 is a block diagram schematically illustrating an electrical configuration of a wireless tag reader used in the wireless tag system of FIG. FIG. 3 is a block diagram schematically illustrating an electrical configuration of a wireless tag used in the wireless tag system of FIG. FIG. 4A is a block diagram schematically illustrating an electrical configuration of a reader-side base station used in the wireless tag system of FIG. FIG. 4B is a block diagram schematically illustrating an electrical configuration of an external base station used in the wireless tag system of FIG.

(Overview of wireless tag system)
First, an overview of the wireless tag system 1 will be described with reference to FIG.
The wireless tag system 1 shown in FIG. 1 has a wireless tag 50 attached to a user (resident of a house, facility user, etc.) who uses an installation place (a house, company, hospital, school, etc.) where the wireless tag reader 10 is set. The wireless tag 50 is configured to be held and monitored. In the following representative example, the wireless tag reader 10 and the reader-side base station 80a are installed in a house 2 owned by an individual, and the wireless tag 50 possessed by a resident of the house 2 is used as the wireless tag reader 10 and the reader-side base station 80a. An occupant detection system configured to monitor by means of:

(Wireless tag reader)
Next, each wireless tag reader 10 will be described with reference to FIG. The wireless tag reader 10 is configured as an RFID tag reader / writer that can read, for example, an RFID tag, and performs communication using an electromagnetic wave with the wireless tag 50 to read information recorded in the wireless tag 50 or to the wireless tag 50. It is configured to write information. As shown in FIG. 2, the wireless tag reader 10 mainly includes a control unit 11, a transmission unit 12, a reception unit 13, and an antenna 14.

  The control unit 11 includes a CPU 31, a memory 32, a timer 33, and the like, and has a configuration that governs overall control of the wireless tag reader 10.

  The transmission unit 12 includes a coding unit 21, a modulation unit 22, an amplification unit 23, and the like, and is configured to output a carrier (carrier wave) having a predetermined frequency from a carrier oscillator (not shown). The encoding unit 21 is connected to the control unit 11, encodes transmission data output from the control unit 11, and outputs the encoded transmission data to the modulation unit 22. The modulation unit 22 is a part to which the carrier (carrier wave) from the carrier oscillator and the transmission data from the encoding unit are input, and when the command (carrier wave) output from the carrier oscillator is transmitted to the communication target A modulated signal, for example, ASK (Amplitude Shift Keying) modulated by the encoded transmission code (modulated signal) output from the encoding unit 21 is generated and output to the amplifying unit 23.

  The amplifying unit 23 amplifies the input signal (the modulated signal modulated by the modulating unit) with a predetermined gain, and outputs the amplified signal to the antenna 14 via a filter, a matching circuit, etc. (not shown). When a transmission signal is output to the antenna 14 in this way, the transmission signal is radiated from the antenna 14 to the outside as an electromagnetic wave.

  The reception unit 13 includes a demodulation unit 25, a decoding unit 26, and the like, and is configured to receive a radio wave signal received by the antenna 14. The receiving unit 13 receives a reception signal from the antenna 14 through a matching circuit (not shown), filters the signal by a filter (not shown), amplifies the signal by an amplifier (not shown), and the amplified signal is demodulated by the demodulation unit 25. Demodulate. Then, the demodulated signal waveform is binarized by a binarization processing unit (not shown), decoded by the decoding unit 26, and then the decoded signal is output to the control unit 11 as received data. The receiving unit 13 is provided with a carrier sense unit 27 that checks whether a channel for emitting radio waves is available.

  In the present embodiment, the wireless tag reader 10 is disposed at a predetermined location in the house 2, and the range (first communication area AR <b> 1) in which radio waves can be transmitted and received in the horizontal direction is the entire area where the house 2 is installed. And the first communication area AR1 is configured around the installation area of the house 2.

(Wireless tag)
Next, the wireless tag 50 will be described with reference to FIG.
The wireless tag 50 is configured, for example, as a known RFID tag in hardware, and includes a control unit 51, an antenna 54, a reception unit 53, a transmission unit 52, a power supply unit 59, and the like as illustrated in FIG. In the example of FIG. 3, the wireless tag 50 is configured as a so-called active tag, and a built-in battery (for example, a lithium coin battery) is provided. The power supply unit 59 receives power supply from the built-in battery, and the control unit Power for operation is supplied to each component including 51.

  The control unit 51 includes a CPU 55, a memory 56, a timer 57, and the like. The CPU 55 performs various controls and arithmetic processes in the wireless tag 50. The memory 56 includes various semiconductor memories such as a ROM, an EEPROM, and a RAM, and various information such as tag identification information (tag ID) for identifying the wireless tag 50 and information handled in communication processing described later. Is to be memorized.

  The receiving unit 53 includes a demodulating unit 65, a decoding unit 66, and the like. In the receiving unit 53, the signal received by the antenna 54 is demodulated by the demodulating unit 65, and the demodulated signal is decoded by the decoding unit 66, thereby outputting the data superimposed on the received signal to the control unit 51. is doing. The receiving unit 53 is also provided with a carrier sense unit 68 that checks whether a channel for emitting radio waves is available.

  The transmission unit 52 mainly includes a coding unit 61, a modulation unit 62, and an amplification unit 63. The transmitter 52 encodes the data output from the controller 51 as transmission data by the encoder 61 and then modulates the data by the modulator 62. The modulated signal is amplified by the amplifying unit 63 and output to the antenna 54. Thus, the transmission data output to the antenna 54 is radiated from the antenna 54 as a radio wave signal.

  The wireless LAN communication unit 70 is configured as a wireless LAN interface that performs wireless LAN communication based on, for example, a known wireless LAN standard (IEEE 802.11 or the like), and transmits and receives radio waves via an antenna 71 according to a predetermined protocol. The base station is configured to perform wireless LAN communication with base stations such as the reader-side base station 80a and the external base station 80b (FIG. 1). In the present embodiment, the wireless tag 50 is configured to perform wireless communication with the reader-side base station 80a and the external base station 80b using a communication packet encrypted by, for example, WEP (Wired Equivalent Privacy). Has been.

(Leader base station)
Next, the reader side base station 80a will be described.
The reader-side base station 80a is configured as a known wireless LAN access point in hardware. As shown in FIG. 4A, the reader-side base station 80a mainly includes an antenna 81a, a wireless transmission / reception unit 82a, and an input unit 84a. A memory 85a, a communication interface 86a, and a control circuit 88a. The wireless transmission / reception unit 82a is configured as an interface for performing wireless LAN communication based on, for example, a known wireless LAN standard (for example, IEEE 802.11), and transmits / receives a wireless signal using radio waves via the antenna 81. It is configured.

  The input unit 84a is a part through which various information can be input, and includes operation buttons and the like. The memory 85a is composed of a ROM, a RAM, a nonvolatile memory, and the like, and is configured to store various information. For example, a MAC (Media Access Control) address for identifying the wireless tag 50 as a wireless LAN client device, and an encryption key used for encrypting data transmitted to and received from the wireless tag 50 are also registered. The communication interface 86a is configured as an interface for performing wired communication with an external device.

  In the present embodiment, the reader-side base station 80a is arranged at a predetermined location in the house 2, and is wider than the range (first communication area AR1) in which radio waves can be transmitted and received by the above-described wireless tag reader 10 and the first base station 80a. The wireless tag 50 is configured to perform wireless LAN communication within the second communication area AR2 including the periphery of the communication area AR1. That is, the range in which radio waves can be transmitted and received by the reader-side base station 80a (second communication area AR2) overlaps the entire first communication area AR, and the second communication area AR2 is also formed around the first communication area AR1. It has come to be.

(External base station)
Next, the external base station 80b will be described.
The external base station 80b is configured as a known wireless LAN access point in terms of hardware, and mainly includes an antenna 81b, a wireless transmission / reception unit 82b, an input unit 84b, as shown in FIG. A memory 85b, a communication interface 86b, and a control circuit 88b are included. The wireless transmission / reception unit 82b is configured as an interface for performing wireless LAN communication based on, for example, a known wireless LAN standard (for example, IEEE 802.11), and transmits / receives a wireless signal using radio waves via the antenna 81. It is configured.

  The input unit 84b is a part through which various information can be input, and includes operation buttons and the like. The memory 85b is composed of a ROM, a RAM, a non-volatile memory, and the like, and is configured to store various information. For example, a MAC (Media Access Control) address for identifying the wireless tag 50 as a wireless LAN client device, and an encryption key used for encrypting data transmitted to and received from the wireless tag 50 are also registered. The communication interface 86b is configured as an interface for performing wired communication with an external device.

  In the present embodiment, the above-described first communication area AR1 in which the external base station 80b is arranged at a predetermined location in a facility (office 3 in the example of FIG. 1) away from the house 2 and is configured by the wireless tag reader 10. , And the second communication area AR2 that is configured by the reader-side base station 80a. The third communication area AR3 is configured to transmit and receive radio waves within a range that does not overlap any of the above-described second communication areas AR2 (third communication area AR3). It is configured to perform wireless LAN communication with the wireless tag 50 arranged inside.

(Communication operation with wireless tag)
Next, a communication operation performed by the wireless tag 50 will be described.
FIG. 5 is a flowchart illustrating the flow of the RFID tag communication process (RFID communication process) performed by operating the tag communication unit (transmission unit 52 and reception unit 53). FIG. 6 is a flowchart illustrating the flow of wireless LAN communication processing performed by operating the wireless LAN communication unit 70. FIG. 7 is a timing chart illustrating the timing of the communication confirmation process by the wireless tag communication process and the radio wave reception timing by the wireless LAN communication process. FIG. 8A is an explanatory diagram conceptually illustrating a frame configuration of transmission data transmitted from the wireless tag to the wireless tag reader. FIG. 8B is an ACK (acknowledgment) transmitted from the wireless tag reader to the wireless tag. FIG. 3 is an explanatory diagram conceptually illustrating the frame configuration of FIG.

  In the present embodiment, the wireless tag communication process shown in FIG. 5 and the wireless LAN communication process shown in FIG. 6 are performed in parallel. 5 and 6 is triggered by power-on or a predetermined external operation on the wireless tag 50 as a trigger.

  In the RFID tag communication process of FIG. 5, a predetermined Δt1 time (for example, 10 seconds) is waited as the process starts (S1). Then, after performing the standby process in S1, a data transmission frame as shown in FIG. 8A is transmitted (S2).

  As shown in FIG. 8, the data transmission frame transmitted in S2 or S5 described later includes a header, a length, a sequence number, a reader ID, a tag ID, a data transmission request command, a checksum, and the like. In the present embodiment, a predetermined first request command for communication confirmation processing is determined in advance, and the first request command is used as a data transmission request command in the data transmission frame transmitted in S2 and S5. It has been included. The reader ID is an ID of the wireless tag reader 10 that is predetermined as a communication target of the wireless tag 50, and the tag ID is a unique ID of the wireless tag 50. Note that both the reader ID and the tag ID are stored in the memory 56 in advance.

  After the process of S2, it is determined whether or not an ACK frame (acknowledgment) is returned from the wireless tag reader 10 for the data transmission frame (S3). The wireless tag reader 10 used in the present embodiment returns an ACK frame (acknowledgment) when a data transmission frame including the first request command can be received from the wireless tag 50. The ACK frame returned from the wireless tag reader 10 has a frame configuration as shown in FIG. 8B, for example. In S3, the reception of such an ACK frame is confirmed. When the reception of the ACK frame (acknowledgment) is confirmed, the process proceeds to Yes in S3, and the processes after S1 are repeated.

  As described above, in the present embodiment, when the wireless tag 50 and the wireless tag reader 10 are in a communicable state (that is, when the wireless tag 50 exists in the communication area (first communication area AR1) of the wireless tag reader 10). The data transmission frame is transmitted every time Δt1 (see “inside home” in FIG. 7).

  Here, the wireless LAN communication process of FIG. 6 will also be described. In the wireless LAN communication process of FIG. 6, the function of the wireless LAN communication unit 70 is stopped immediately after the process is started (S21). Then, while maintaining the stop state, it is determined whether or not the wireless tag 50 can communicate with the wireless tag reader 10 (S22). Specifically, the process of S22 determines whether or not the wireless tag 50 has acquired an ACK frame from the wireless tag reader 10 (that is, whether or not Yes is determined in S3 of FIG. 5). If the ACK frame is not confirmed, the process proceeds to No in S22, and as long as the ACK frame is confirmed, the process proceeds to Yes in S22.

  In the present embodiment, the control unit 51 and the wireless LAN communication unit 70 correspond to an example of “wireless LAN communication means”, function to perform wireless LAN communication with the reader-side base station 80a, and further, wireless tag 50 and wireless LAN communication When the tag reader 10 is in a communicable state, wireless LAN communication with the reader-side base station 80a is suspended (see “in-home” in FIG. 7).

Here, returning to FIG. 5, the description of the wireless tag communication process will be continued.
If an ACK frame (acknowledgment) is not returned for the data transmission frame transmitted in S2, the process proceeds to No in S3, waits for a predetermined Δt2 time (for example, 3 seconds) (S4), and in S4 After performing the standby process, the same data transmission frame (FIG. 8A) as in S2 is transmitted (S5), and an ACK frame (acknowledgment) is returned from the wireless tag reader 10 in response to this data transmission frame. It is determined whether or not (S6). If it is determined in S6 that the ACK frame has been confirmed (that is, if the wireless tag 50 enters the first communication area AR1 again), the process proceeds to Yes in S6, and the processes after S1 are repeated.

  On the other hand, if it is determined in S6 that the ACK frame is not confirmed (that is, if the wireless tag 50 is maintained at a position outside the first communication area AR1), the process proceeds to No in S6, and the reader-side base station 80a It is determined whether or not the unique ID (SSID (Service Set IDentifier)) transmitted from the terminal can be received. In this embodiment, the unique ID transmitted from the reader-side base station 80a is “SSIDj”. In S7, it is determined whether or not this SSIDj is received. If the SSIDj is receivable (that is, if the wireless tag 50 exists in the communication area (second communication area AR2) of the reader-side base station 80a), the process proceeds to Yes in S7, and the processes after S4 repeat. On the other hand, when SSIDj is not receivable (that is, when the wireless tag 50 is out of the communication area (second communication area AR2) of the reader-side base station 80a), the process proceeds to No in S7, and the tag communication unit (transmission) The functions of the unit 52 and the receiving unit 53) are stopped. While the function is stopped in S8, the output of the carrier from the transmission unit 52 is stopped, and the driving of the reception unit 53 is also stopped.

  In the present embodiment, the control unit 51, the transmission unit 52, and the reception unit 53 correspond to an example of “wireless tag communication means”, and function to periodically perform communication confirmation processing on the wireless tag reader 10. Specifically, the communication confirmation processing interval for the wireless tag reader 10 is changed according to the state of wireless LAN communication between the wireless LAN communication means and the reader-side base station 80a. For example, the communication confirmation processing interval Δt2 when the response from the wireless tag reader 10 cannot be received and the wireless LAN communication means can communicate with the reader-side base station 80a is used. The interval is set to be shorter than the communication confirmation processing interval Δt1. The “wireless tag communication means” is used when the response from the wireless tag reader 10 cannot be received and the wireless LAN communication means cannot communicate with the reader-side base station 80a (that is, when No in S7). In addition, the communication confirmation process is suspended.

  Here, the processes after S22 in the wireless LAN communication process of FIG. 6 will be described. In the wireless LAN communication process of FIG. 6, when an ACK frame (acknowledgment) is not returned for the data transmission frame transmitted in S2 (that is, when the wireless tag 50 cannot communicate with the wireless tag reader 10), S22 The process proceeds to No and waits for a predetermined Δt3 time (for example, 20 seconds) (S23). After the standby process is performed in S23, it accepts an external wireless LAN communication radio wave and waits to receive an SSID. Perform (S24).

  After S24, it is determined again whether or not the wireless tag 50 can communicate with the wireless tag reader 10 (S25). Even in S25, it is determined whether or not the wireless tag 50 has acquired an ACK frame from the wireless tag reader 10, and when it is acquired (that is, when the wireless tag 50 has returned to the communication area of the wireless tag reader 10), the process proceeds to S25. Then, the process proceeds to Yes, and the processes after S21 are repeated. On the other hand, when the ACK frame is not yet acquired (that is, when the wireless tag 50 is maintained outside the communication area of the wireless tag reader 10), the process proceeds to No in S25.

  When the process proceeds to No in S25, it is determined whether or not the unique ID (SSIDj) transmitted from the reader-side base station 80a can be received (S26). If the SSIDj is receivable (that is, if the wireless tag 50 exists in the communication area (second communication area AR2) of the reader-side base station 80a), the process proceeds to Yes in S26, and the processes after S23 repeat. Since the process is performed in this way, when the wireless tag 50 exists outside the communication area (first communication area AR1) of the wireless tag reader 10 and within the communication area (second communication area AR2) of the reader-side base station 80a. , Processing for accepting reception of SSIDj is performed every Δt3 (see “SSIDj detection” in “around home” in FIG. 7).

  On the other hand, if it is determined in S26 that SSIDj is not received, the process proceeds to No in S26, waits for a predetermined Δt4 time (for example, 10 minutes) (S27), and performs a standby process in S27. After that, the wireless LAN communication radio wave from the outside is received and the SSID reception standby is performed (S28).

  After S28, it is determined again whether or not the wireless tag 50 has received SSIDj from the reader-side base station 80a (S29). When the wireless tag 50 receives SSIDj from the reader-side base station 80a (that is, when the wireless tag 50 returns to the communication area (second communication area AR2) of the reader-side base station 80a), the process goes to S29. Then, the process proceeds to YesNo, and the processes after S23 are repeated. On the other hand, when the wireless tag 50 still does not receive SSIDj from the reader-side base station 80a (that is, when the wireless tag 50 is maintained outside the communication area of the reader-side base station 80a), the process proceeds to No in S29. .

  When the process proceeds to No in S29, it is determined whether or not the unique ID (SSIDk) transmitted from the external base station 80b can be received (S30). If the SSIDk cannot be received (that is, if the wireless tag 50 does not exist in the communication area (third communication area AR3) of the external base station 80b), the process proceeds to No in S30, and the processes after S27 are performed. repeat. Since the process is performed as described above, when the wireless tag 50 exists outside the communication area of the reader-side base station 80a and the external base station 80b, a process of accepting reception of SSIDj is performed every Δt4 ( (See SSID undetected in “Attendance” and “Exit” in FIG. 7).

  On the other hand, if it is determined in S30 that SSIDk can be received, the process proceeds to Yes in S30, waits for a predetermined Δt5 time (for example, 30 minutes) (S31), and after performing the standby process in S31 Then, it accepts wireless LAN communication radio waves from the outside and waits to receive SSID (S32). Then, after S32, it is determined again whether or not the wireless tag 50 has received SSIDk (S33). If it is received, the process proceeds to Yes in S33, and the processes after S31 are repeated. On the other hand, when it becomes impossible to receive SSIDk (that is, when it is out of the communication area (third communication area) of the external base station 80b), the process proceeds to No in S33, and the processes after S27 are repeated. Since it is configured in this manner, when the wireless tag 50 exists in the communication area (third communication area AR3) of the external base station 80b, a process of accepting reception of SSIDk is performed every Δt5 (FIG. 7 (see SSID not detected in “in office”).

  As described above, in this embodiment, the “wireless LAN communication means” (the control unit 51, the transmission unit 52, and the reception unit 53) performs wireless LAN communication performed between the wireless tag 50 and the reader-side base station 80a. The interval of the radio wave reception process in the wireless LAN communication is changed according to at least one of the state and the state of wireless LAN communication performed between the wireless tag 50 and the external base station 80b. Specifically, when the wireless tag 50 is capable of wireless LAN communication with the reader-side base station 80a, the radio wave reception processing interval is set to a predetermined first interval Δt3 and wirelessly communicated with the external base station 80b. When LAN communication is possible, the radio wave reception processing interval is set to a second interval Δt5 that is longer than the first interval Δt3. Furthermore, when the wireless LAN communication with the external base station 80b changes from a state where wireless LAN communication is possible to an impossible state, the radio wave reception interval is set to a third interval Δt4 which is shorter than the second interval Δt5.

(Main effects of the first embodiment)
The wireless tag system 1 according to the present embodiment includes a wireless tag 50 including a built-in battery, a wireless tag reader 10 that reads the wireless tag 50 within a predetermined first communication area AR1, and a first communication configured by the wireless tag reader 10. A reader-side base station 80a that performs wireless LAN communication with the wireless tag 50 in the second communication area AR2 that is wider than the area AR1 and includes the periphery of the first communication area AR1 is provided. The wireless tag 50 is provided with a wireless tag communication unit that periodically performs communication confirmation processing with respect to the wireless tag reader 10, and a wireless LAN communication unit that performs wireless LAN communication with the reader-side base station 80a. The wireless tag communication unit changes the communication confirmation processing interval for the wireless tag reader 10 according to the state of wireless LAN communication between the wireless LAN communication unit and the reader-side base station 80a.
In this case, even when the wireless tag 50 is out of the communication area (first communication area AR1) of the wireless tag reader 10, wireless LAN communication with the reader-side base station 80a is possible (that is, the wireless tag reader 10). When the communication area is close to the communication area, it is easy to adjust the communication confirmation processing interval for the wireless tag reader 10 to an interval suitable for the position. In particular, it becomes easier to save power compared to a configuration in which the interval of communication confirmation processing is set to be short regardless of the proximity of the wireless tag reader 10 to the communication area.

  Further, the wireless tag communication means provided in the wireless tag 50 has a communication confirmation processing interval Δt2 when a response from the wireless tag reader 10 cannot be received and the wireless LAN communication means can communicate with the reader-side base station 80a. Is set shorter than the communication confirmation processing interval Δt1 when a response can be received from the wireless tag reader 10. In this way, when the wireless tag 50 is present near the first communication area AR1 outside the communication area (first communication area AR1) of the wireless tag reader 10, it is more than when the wireless tag 50 is present in the first communication area AR1. Communication confirmation processing is frequently performed. Therefore, the wireless tag reader 10 can detect the wireless tag 50 that is about to enter the first communication area AR1 at an early stage from the vicinity of the first communication area AR1.

  The wireless tag communication means provided in the wireless tag 50 performs communication confirmation processing when a response from the wireless tag reader 10 cannot be received and the wireless LAN communication means cannot communicate with the reader-side base station 80a. Paused. According to this configuration, when the wireless tag 50 moves away from the communication range of the wireless tag reader 10 and the possibility of communication is reduced, it is possible to effectively save power.

  The wireless LAN communication means of the wireless tag 50 suspends wireless LAN communication performed with the reader-side base station 80a when the wireless tag 50 and the wireless tag reader 10 are in a communicable state. According to this configuration, when the wireless tag 50 has already been grasped in the communication area of the wireless tag reader 10 and it is not necessary to grasp the positional relationship by wireless LAN communication, the wireless LAN is suspended and appropriately Power saving can be achieved.

Further, the wireless LAN communication means of the wireless tag 50 suspends wireless LAN communication performed with the reader-side base station 80a when the confirmation signal (SSIDj) from the reader-side base station 80a becomes unreceivable for a certain period. Then, the wireless LAN communication processing with the outside is started when a predetermined start condition is satisfied. Specifically, when the answer is No in S26, wireless LAN communication is suspended for Δt4 (10 minutes), and wireless LAN communication processing with the outside is started after 10 minutes have elapsed.
According to this configuration, when the wireless tag 50 cannot receive the confirmation signal from the reader-side base station 80a for a certain period of time, it is highly likely that the wireless tag 50 has left the communication area of the reader-side base station 80a (that is, When the wireless tag 50 is less likely to perform wireless LAN communication with the reader-side base station 80a at the most recent time), the wireless LAN communication can be suspended to appropriately save power.
In the present embodiment, the pause period when the confirmation signal from the reader-side base station 80a becomes unreceivable for a certain period is 10 minutes, but a longer or shorter time interval may be used. Alternatively, when the confirmation signal from the reader-side base station 80a cannot be received for a certain period, the wireless LAN communication may be suspended until a predetermined operation is performed on the wireless tag 50.

In the present embodiment, an external base station 80b capable of wireless LAN communication with the wireless tag 50 arranged in a predetermined third communication area AR3 that does not overlap the first communication area AR1 is provided. The wireless LAN communication means of the wireless tag 50 includes at least one of a state of wireless LAN communication performed with the reader-side base station 80a and a state of wireless LAN communication performed with the external base station 80b. The interval of radio wave reception processing in wireless LAN communication is changed according to the communication state.
In this way, the wireless tag 50 is in a state where it can communicate with the reader-side base station 80a close to the wireless tag reader 10, or the wireless tag 50 is in a state where it can communicate with the external base station 80b far from the wireless tag reader 10. Or the wireless tag 50 can accurately grasp whether it is in a state where communication with any base station is possible, and the interval of the radio wave reception processing performed by the wireless tag 50 depends on the position of the wireless tag 50. It can be changed appropriately.

Further, the wireless LAN communication means of the wireless tag 50 sets the interval of radio wave reception processing when wireless LAN communication is possible with the reader-side base station 80a to a predetermined first interval Δt3, and Is set to a second interval Δt5 that is longer than the first interval Δt3.
In this case, when communication is possible with the external base station 80b in which a communication area farther from the communication area (first communication area AR1) of the wireless tag reader 10 is set (that is, the wireless tag 50 is connected to the communication area of the wireless tag reader 10). The interval of the radio wave reception processing can be set relatively long when the communication with the wireless tag reader 10 is unlikely to be performed immediately. Therefore, it is unlikely that communication with the wireless tag reader 10 is performed, and it is possible to appropriately grasp the state in which the result of wireless LAN communication hardly affects the detection of the wireless tag reader 10 and effectively save power.

The wireless LAN communication means of the wireless tag 50 sets the interval of radio wave reception processing when the wireless LAN communication is possible with the external base station 80b to the second interval Δt5, and When the wireless LAN communication is changed from a state where wireless LAN communication is possible, the radio wave reception interval is set to a third interval Δt4 which is shorter than the second interval Δt5.
According to this configuration, when the wireless tag 50 is likely to move away from the communication area (third communication area AR3) of the external base station 80b and approach the wireless tag reader 10, the frequency of radio wave reception processing for wireless LAN communication is reduced. Can be increased. Therefore, when the wireless tag 50 reaches the communication area of the reader-side base station 80a, wireless LAN communication can be performed quickly.

[Other Embodiments]
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  In the above embodiment, the antenna 54 used for the tag transmission unit (transmission unit 52, reception unit 53) and the antenna 71 used for the wireless LAN communication unit 70 are configured by separate antennas, but the tag transmission unit ( The transmission unit 52, the reception unit 53), and the wireless LAN communication unit 70 may all be configured to transmit and receive radio waves via a shared antenna.

In addition to the above embodiment, a clock (clock means) capable of acquiring current time information is provided in the wireless tag 50, and the attendance time is registered in the memory 56 (attendance time registration means) in advance. You may do it. Then, the control unit 51 and the wireless LAN communication unit 70 corresponding to “wireless LAN communication means” are acquired by the attendance time registered in the memory 56 (attendance time registration means) and the clock (clock means) in the wireless tag 50. On the basis of the current time information, the wireless LAN communication suspension time when the confirmation signal from the reader-side base station 80a cannot be received for a certain period may be set.
In this case, there is a high possibility that the wireless tag 50 has moved away from the communication area of the reader-side base station 80a (that is, the wireless tag 50 may perform wireless LAN communication with the reader-side base station 80a at the most recent time. Wireless LAN communication can be suspended to achieve appropriate power savings, while the wireless LAN communication suspension time Δt4 at that time is the registered attendance time and the current time measured. Can be set appropriately.
For example, in the example of FIG. 5 and FIG. 7, when the confirmation signal (SSIDj) from the reader-side base station 80a becomes unreceivable for a certain period, the process proceeds to No in S26 and waits for Δt4 (for example, 10 minutes) in S27. After performing the standby process, the hibernation state is canceled and the SSID is waited. However, the time Δt4 used in S27 may be changed depending on the relationship between the registered attendance time and the current time. For example, when the current time is acquired at S27 and the current time is a predetermined time (for example, 1 hour) or more or a predetermined time (for example, 1 hour) or more after the registered attendance time (for example, 7:30) May set the pause time Δt4 to be shorter (for example, set to 3 minutes), and if not, the pause time Δt4 may be set to be longer (for example, set to 10 minutes).
In this way, when the current time at which the processing of S27 is performed is a time zone far from the registered attendance time, it is highly likely that the attendance is not going out due to attendance, so it is possible to set a short rest time to cope with a sudden return home. In addition, when the current time at which the process of S27 is performed is close to the registered attendance time, there is a high possibility of going out due to attendance, so it is possible to save power by setting the suspension time relatively long. .

In addition to the above embodiment, a calendar (calendar means) capable of acquiring the current date or day of the week may be provided, and the attendance date may be registered in the memory 56 (attendance day registration means) in the wireless tag 50. Then, the control unit 51 and the wireless LAN communication unit 70 corresponding to the “wireless LAN communication unit” include an attendance date registered in the memory 56 (attendance date registration unit) and a current date acquired by the calendar (calendar unit). Alternatively, the wireless LAN communication suspension time may be set when the confirmation signal (SSIDj) from the reader-side base station 80a becomes unreceivable for a certain period based on the day of the week.
In this case, there is a high possibility that the wireless tag 50 has moved away from the communication area of the reader-side base station 80a (that is, the wireless tag 50 may perform wireless LAN communication with the reader-side base station 80a at the most recent time. When the wireless LAN communication is stopped, the wireless LAN communication can be suspended to appropriately save power. On the other hand, the wireless LAN communication suspension time is set to the registered work day and the current date or day of the week. Can be set appropriately.
For example, in the example of FIG. 5 and FIG. 7, when the confirmation signal (SSIDj) from the reader-side base station 80a becomes unreceivable for a certain period, the process proceeds to No in S26 and waits for Δt4 (for example, 10 minutes) in S27. After performing standby processing, the hibernation state is canceled and SSID standby is performed, but the time of Δt4 used in S27 is changed depending on the registered work day and the current day of the week or date obtained by the calendar. May be. For example, when the current day of the week is acquired at S27 and the current day of the week is not a registered work day (eg, Monday to Friday), the suspension time Δt4 is set short (eg, set to 3 minutes), When the day of the week is a registered working day (for example, Monday to Friday), the suspension time Δt4 may be set longer (for example, set to 10 minutes).
In this way, when the current day of the week on which the process of S27 is performed is other than the registered attendance day (for example, Saturday and Sunday), there is a high possibility that it is not an outing due to attendance. Thus, when the current day of the week on which the process of S27 is performed is a registered work day (for example, Monday to Friday), there is a high possibility of going out due to work, so the downtime is set relatively long to save power. be able to.

DESCRIPTION OF SYMBOLS 1 ... Wireless tag system 10 ... Wireless tag reader 50 ... Wireless tag 51 ... Control part (wireless LAN communication means, wireless tag communication means)
52. Transmission unit (wireless tag communication means)
53. Receiving part (wireless tag communication means)
70: Wireless LAN communication unit (wireless LAN communication means)
80a ... Reader side base station 80b ... External base station AR1 ... First communication area AR2 ... Second communication area AR3 ... Third communication area

Claims (8)

A wireless tag with a built-in battery;
A wireless tag reader that reads the wireless tag within a predetermined first communication area;
A reader-side base station that performs wireless LAN communication with the wireless tag in a second communication area that is wider than the first communication area configured by the wireless tag reader and includes the periphery of the first communication area;
With
The wireless tag is
Wireless tag communication means for periodically performing communication confirmation processing on the wireless tag reader;
Wireless LAN communication means for performing wireless LAN communication with the reader-side base station;
Have
The wireless tag communication means changes a communication confirmation processing interval for the wireless tag reader according to a state of wireless LAN communication between the wireless LAN communication means and the reader-side base station. Tag system.   The wireless tag communication means responds from the wireless tag reader to the communication confirmation processing interval when the response from the wireless tag reader is not received and the wireless LAN communication means can communicate with the reader-side base station. The wireless tag system according to claim 1, wherein the wireless tag system is set to be shorter than an interval of the communication confirmation processing when the communication is receivable.   The wireless tag communication unit pauses the communication confirmation process when a response from the wireless tag reader is not received and the wireless LAN communication unit cannot communicate with the reader-side base station. The wireless tag system according to any one of claims 1 and 2.   The wireless LAN communication unit suspends wireless LAN communication performed with the reader-side base station when the wireless tag and the wireless tag reader are in a communicable state. The wireless tag system according to claim 3.   The wireless LAN communication means pauses wireless LAN communication performed with the reader-side base station when a confirmation signal from the reader-side base station becomes unreceivable for a certain period, and a predetermined start condition is satisfied The wireless tag system according to any one of claims 1 to 4, wherein the wireless LAN communication processing with the outside is started sometimes. An external base station capable of wireless LAN communication with the wireless tag disposed in a predetermined third communication area that does not overlap the first communication area;
The wireless LAN communication means is in a communication state at least one of a state of wireless LAN communication performed with the reader-side base station and a state of wireless LAN communication performed with the external base station. The radio tag system according to claim 1, wherein an interval of radio wave reception processing in wireless LAN communication is changed accordingly.   The wireless LAN communication means sets an interval of radio wave reception processing when wireless LAN communication is possible with the reader-side base station to a predetermined first interval, and performs wireless LAN communication with the external base station. The radio tag system according to claim 6, wherein an interval of radio wave reception processing when the radio wave is possible is set to a second interval longer than the first interval. The wireless LAN communication means includes
An interval of radio wave reception processing when wireless LAN communication is possible with the external base station is set to the second interval;
8. The radio wave reception interval is set to a third interval shorter than the second interval when wireless LAN communication with the external base station is changed from a possible state to an impossible state. The wireless tag system described in 1.

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