JP2012124657A - Active tag communication method and active tag communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a tag for a long period of time even when the number of times of transmission increases by reducing power consumption of the tag, in an active tag communication system in which a transmission cycle needs to be made short in order to cope with high-speed movement.SOLUTION: In an active tag communication method, a tag 10 for transmitting a radio frame in a prescribed transmission cycle and a reader 20 for receiving the radio frame transmitted from the tag 10 are provided, and communication is performed between the fixed tag 10 and the moving reader 20. The radio frame of the tag 10 does not include ID data for specifying the tag 10. The reader 20 includes storage means for storing the position information on the tag 10 and the ID data in correspondence, refers to the storage means on the basis of the position information on the reader 20 detected by using prescribed position information detection means, acquires the ID data corresponding to the position information, specifies the tag 10 which has transmitted the radio frame, and executes reception processing of the radio frame.

Description

  The present invention relates to an active tag communication method and an active tag communication system for power saving of an active tag.

  The active tag communication system includes a tag having a power source and a reader that receives ID and sensor information transmitted from the tag (Non-Patent Document 1). By transmitting radio waves from a tag having a power source, long-distance communication of, for example, about 10 to 100 m is possible, and the range of use is greatly expanded.

  A conventional active tag communication system assumes communication in a stationary state or communication during low-speed movement such as a belt conveyor for article management, for example, and the tag transmission cycle may be set to several tens of seconds or more, for example. There were many. However, in an active tag communication system in which at least one of a tag and a reader is mounted on a vehicle and moves at a high speed of several tens of kilometers, for example, the tag and the tag are transmitted in order to perform communication within a limited communication area. Need to be shortened. However, if the transmission cycle of the tag that uses the battery as a power source is shortened, the number of transmissions increases, the battery life is shortened, and the tag cannot be used for a long time.

Shiro Sakata, Satoshi Shimamoto, “Encyclopedia of Wireless Communication Technology”, pp.349-354, Rick Telecom, February 2007

  The current consumption of the tag is about several to several tens of μA in the standby state, but is several to several tens of mA during signal transmission. Therefore, a method for realizing power saving by suppressing current consumption at the time of signal transmission has been studied. However, at present, a technique for reducing current consumption to the order of several μA has not been realized.

  The present invention relates to an active tag communication system that enables a long-term use even if the number of transmissions is increased by reducing the power consumption of the tag in an active tag communication system that needs to shorten the transmission cycle in order to cope with high-speed movement. It is an object to provide a method and an active tag communication system.

  A first invention includes a tag that transmits a radio frame at a predetermined transmission cycle and a reader that receives a radio frame transmitted from the tag, and performs active communication between a fixedly arranged tag and a moving reader In the tag communication method, the tag radio frame does not include ID data for specifying the tag, and the reader includes storage means for storing the tag position information and the ID data in association with each other, and has a predetermined position. Based on the position information of the reader detected using the information detection means, the storage means is referred to, ID data corresponding to the position information is obtained, the tag that transmitted the radio frame is specified, and the radio frame is received. To do.

  The second invention includes a tag that transmits a radio frame at a predetermined transmission cycle and a reader that receives a radio frame transmitted from the tag, and performs active communication between a fixedly arranged tag and a moving reader In the tag communication method, the wireless frame of the tag is configured to include simple ID data of several bits or less for identifying a small number of adjacent tags, and the reader is ID data for specifying the tag position information, the simple ID data, and the tag. Are stored in association with each other, and the storage means is referred to based on the position information of the reader detected using the predetermined position information detection means and the simple ID data of the received radio frame, and the position information and ID data corresponding to the simple ID data is acquired, the tag that transmitted the radio frame is specified, and the radio frame is received.

  In the active tag communication method according to the first or second invention, the predetermined position information detecting means detects the position information of the reader by receiving the GPS signal.

  A third invention includes a tag that transmits a radio frame at a predetermined transmission cycle and a reader that receives a radio frame transmitted from the tag, and performs active communication between a fixedly arranged tag and a moving reader In the tag communication method, the tag radio frame does not include ID data for specifying the tag, and an ID notification radio frame including the tag ID data is transmitted from the ID notification tag arranged in the vicinity of the tag. The reader receives the wireless frame transmitted from the tag and the ID notification wireless frame transmitted from the ID notification tag, acquires the ID data from the ID notification wireless frame, and selects the tag that transmitted the wireless frame. The radio frame is identified and processed.

  4th invention has the tag which transmits a radio | wireless frame with a predetermined transmission period, and the reader which receives the radio | wireless frame transmitted from the tag, and is active which communicates between the tag of fixed arrangement | positioning, and the moving reader | leader In the tag communication system, the tag is configured to transmit a radio frame that does not include ID data for specifying the tag, and the reader includes storage means for storing the tag position information and ID data in association with each other, and a predetermined unit. Based on the position information of the reader detected using the position information detection means, the storage means is referred to, ID data corresponding to the position information is acquired, the tag that transmitted the radio frame is specified, and the radio frame is received. And processing means for processing.

  A fifth invention includes a tag that transmits a radio frame at a predetermined transmission cycle and a reader that receives a radio frame transmitted from the tag, and performs active communication between a fixedly arranged tag and a moving reader In a tag communication system, a tag is configured to transmit a radio frame including simple ID data of several bits or less that identifies a small number of adjacent tags, and a reader specifies tag position information, simple ID data, and a tag. The storage means for storing the ID data in association with each other, the position information of the reader based on the position information of the reader detected using the predetermined position information detection means and the simple ID data of the received radio frame, and the position information And processing means for acquiring ID data corresponding to the simple ID data, specifying the tag that transmitted the radio frame, and receiving the radio frame Equipped with a.

  In the active tag communication system according to the fourth or fifth invention, the predetermined position information detecting means is configured to detect the position information of the reader by receiving a GPS signal.

  A sixth invention includes a tag that transmits a radio frame at a predetermined transmission cycle and a reader that receives a radio frame transmitted from the tag, and performs active communication between a fixedly arranged tag and a moving reader In a tag communication system, a tag is configured to transmit a radio frame that does not include ID data that identifies the tag, and is arranged in the vicinity of the tag, and an ID notification that transmits an ID notification radio frame including the ID data of the tag The reader receives a wireless frame transmitted from the tag and an ID notification wireless frame transmitted from the ID notification tag, acquires ID data from the ID notification wireless frame, and transmits the wireless frame. And a processing means for receiving the radio frame by specifying the tag.

  The present invention shortens the frame length by deleting all or part of ID data specifying a tag from a wireless frame transmitted and received between the tag and the reader, and reduces power consumption during signal transmission by shortening the transmission time. Reduce. Thereby, the use period of the tag incorporating a battery can be lengthened.

It is a figure which shows the structural example of Example 1 of the active tag communication system of this invention. FIG. 3 is a diagram illustrating an example of a frame format of a radio frame according to the first embodiment. 2 is a diagram illustrating a configuration example of a tag 10 and a reader 20 according to the first embodiment. FIG. It is a figure which shows the structural example of Example 2 of the active tag communication system of this invention. 6 is a diagram illustrating an example of a frame format of a radio frame according to Embodiment 2. FIG. It is a figure which shows the structural example of Example 3 of the active tag communication system of this invention. 10 is a diagram illustrating an example of a frame format of a radio frame according to Embodiment 3. FIG. FIG. 6 is a diagram illustrating a configuration example of a data communication tag 10, an ID notification tag 40, and a reader 20 according to a third embodiment.

FIG. 1 shows a configuration example of Embodiment 1 of the active tag communication system of the present invention.
1, the active tag communication system according to the first embodiment includes a tag 10 installed in a manhole 1 on a road, a reader 20 and a GPS device 30 mounted on a vehicle 2 traveling on the road. The tag 10 installed in the manhole 1 on the road transmits data collected by the sensor 3 in the manhole 1 as a radio frame at a predetermined transmission cycle. On the other hand, the reader 20 mounted on the vehicle 2 traveling on the road receives the radio frame and acquires data collected by the sensor 3.

  Here, assuming that the communication range of the tag 10 and the reader 20 is, for example, a radius of 10 m from the tag 10 and the traveling speed of the vehicle 2 is, for example, 60 km / hour (16.7 m / second), the vehicle 2 is traveling 20 m of the communication range In addition, in order for the reader 20 to receive a wireless frame transmitted by the tag 10, the transmission cycle of the wireless frame needs to be set shorter than about 1 second.

  In the present invention, in order to reduce the power consumption of the tag 10 without maintaining such a transmission cycle, the transmission time is shortened by shortening the frame length of the radio frame transmitted by the tag 10. It is characterized by reducing power consumption.

  In the first embodiment, the reader 20 identifies the tag 10 near the vehicle from the position information of the vehicle 2 obtained by the GPS device 30. That is, the reader 20 has a table that associates the position information of the tag 10 with the ID data, specifies the ID data of the tag 10 from the position information input from the GPS device 30 with reference to the table, and the received radio frame Associate tags. As a result, the ID data can be omitted from the radio frame transmitted by the tag 10, and the power consumption during signal transmission can be reduced by shortening the frame length.

  The means for the reader 20 to acquire the position information is not limited to the GPS device 30 using the GPS signal, but may be any position information detection means having equivalent position specifying accuracy. The same applies to Example 2 described below.

FIG. 2 illustrates an example of a frame format of the radio frame according to the first embodiment.
In FIG. 2, the conventional frame format is a total of 7 bytes (56 bits) including a preamble 1 byte, ID data 4 bytes, sensor data 1 byte, and EOF (error detection) 1 byte. In the frame format of the first embodiment, the ID data area is deleted, and the total of 3 bytes (24 bits) including a preamble 1 byte, sensor data 1 byte, and EOF (error detection) 1 byte. If the transmission speed between the tag 10 and the reader 20 is 2400 bps, the transmission time is greatly reduced from 23.3 ms to 10 ms by shortening the frame length from 7 bytes to 3 bytes. Power consumption during transmission can be reduced.

FIG. 3 shows a configuration example of the tag 10 and the reader 20 of the first embodiment.
In FIG. 3, the tag 10 includes a data processing unit 11 that processes data input from the sensor 3 and generates a radio frame, and a transmission unit 12 that transmits the radio frame at a predetermined transmission cycle. The ID data of the wireless frame is deleted as shown in FIG. 2, and the reader 20 cannot usually determine from which tag the data is transmitted.

  The reader 20 includes a position specifying unit 21 that inputs position information from the GPS device 30, a storage unit 22 that stores the position information of the tag 10 and ID data in association with each other, and the position information obtained by the position specifying unit 21. The tag ID determination unit 23 that determines the ID data of the tag corresponding to the position information, the reception unit 24 that receives the radio frame transmitted from the tag 10, and the tag ID determination unit A data processing unit 25 that processes the sensor data of the wireless frame received by the receiving unit 24 based on the tag ID data determined in 23 as being transmitted from the tag.

  In the first embodiment, one tag is obtained from GPS position information as in the case where the interval between adjacent tags is sufficiently large (for example, several tens of meters) with respect to the GPS position specifying accuracy (for example, several meters). Applicable when identifiable. On the other hand, if the relationship between the GPS position specifying accuracy and the tag interval is reversed, the tag cannot be uniquely specified from the GPS position information. In order to cope with such a situation, the second embodiment is characterized in that the frame length is shortened by shortening the ID data by complementarily using the GPS position information and the simple ID data of each tag. .

FIG. 4 shows a configuration example of Embodiment 2 of the active tag communication system of the present invention.
4, the active tag communication system according to the second embodiment includes a tag 10A installed in a manhole 1A on a road, a tag 10B installed on a manhole 1B, a reader 20 and a GPS mounted on a vehicle 2 traveling on the road. The device 30 is configured. The tags 10A and 10B transmit the data collected by the sensors 3A and 3B, respectively, and the reader 20 receives each wireless frame and acquires the data collected by the sensors 3A and 3B. Here, it is assumed that the tags 10A and 10B are close to each other compared with the GPS position specifying accuracy, and the tags 10A and 10B cannot be distinguished from the GPS position information.

  As shown in FIG. 5, the frame format of the radio frame transmitted from each of the tags 10A and 10B is assigned 1 bit for identifying two tags as simple ID data, 1 byte for preamble, 1 byte for sensor data, EOF (Error detection) 1 byte is 25 bits.

  In the second embodiment, the reader 20 has a table that associates the position information of the tags 10A and 10B, the 1-bit simple ID data, and the original ID data for identifying the tag, and refers to the table to refer to the GPS device 30. The original ID data of the tags 10A and 10B is specified from the position information inputted from the above and the simple ID data of the received frame, and the received frame is associated with the tag. As a result, the ID data of the radio frame transmitted by the tags 10A and 10B can be shortened from 32 bits to 1-bit simple ID data, and the power consumption during signal transmission can be reduced by shortening the frame length.

  If there are three or more tags that are close to the GPS position identification accuracy, the number of bits of simple ID data that can identify them may be assigned. However, 32 bits are not necessary as ID data as in the prior art, and if the tag is 4 or less, 2 bits are sufficient, and the effect of shortening the frame length is extremely great.

  When a plurality of tags are close to each other, there may be a case where radio frames transmitted from these tags collide and the reader cannot receive them. However, if the transmission speed between the tag and the reader is 2400 bps and the frame length is 25 bits, the transmission / reception time is about 10 ms, so the collision probability is about 1/10 even if each tag transmits at 100 ms intervals. Degree. Moreover, even if a collision occurs, the probability of reception failing twice or more consecutively is very low due to the collision avoidance function that randomly spreads the transmission interval within a certain range.

  The configurations of the tag 10 and the reader 20 of the second embodiment are basically the same as those of the first embodiment shown in FIG. 3 except for the following points. The data processing unit 11 of the tag 10 forms a radio frame including simple ID data. The storage unit 22 of the reader 20 stores the position information of the tag 10, simple ID data, and original ID data in association with each other. The data processing unit 25 of the reader 20 notifies the simple ID data obtained from the received wireless frame to the tag ID determining unit 23, and the tag ID determining unit 23 receives the position information obtained by the position specifying unit 21 and the received wireless information. Based on the simple ID data obtained from the frame, the storage unit 22 is referenced to determine the original ID data of the tag. Based on the tag ID data determined by the tag ID determination unit 23, the data processing unit 25 processes the wireless frame sensor data received by the reception unit 24 as being transmitted from the tag.

  In the first and second embodiments, the tag length is specified by using the GPS position information so that the frame length can be shortened by deleting all or part of the ID data of the radio frame. The third embodiment is characterized in that an ID notification tag and a data communication tag are installed instead of using GPS position information, and the reader receives each wireless frame transmitted from each tag.

FIG. 6 shows an example of the configuration of Embodiment 3 of the active tag communication system of the present invention.
In FIG. 6, the active tag communication system according to the third embodiment travels on the road with the data communication tag 10 installed in the manhole 1 on the road and the ID notification tag 40 installed on the ground near the manhole 1. The reader 20 is mounted on the vehicle 2. The frame format of the wireless frame transmitted from the data communication tag 10 is 3 in the same manner as in the first embodiment, except that the ID data area is deleted and the preamble 1 byte, sensor data 1 byte, and EOF (error detection) 1 byte are combined. It is a byte (24 bits). Therefore, in the tag 10 for data communication, the power consumption at the time of signal transmission can be reduced by shortening the frame length.

  On the other hand, as shown in FIG. 7, the frame format of the radio frame transmitted from the ID notification tag 40 is 6 bytes (48 bits) in total: 1 byte of preamble, 4 bytes of ID data, and 1 byte of EOF (error detection). is there. Therefore, although the effect of shortening the frame length is small compared with the conventional radio frame, the communication distance equivalent to the tag 10 in the manhole 1 is secured even if the transmission power is lowered by installing the ID notification tag 40 on the ground. can do. Thereby, the power consumption at the time of signal transmission in the ID notification tag 40 can be reduced, and even when combined with the power consumption of the tag 10 for data communication, the power consumption of the conventional tag can be reduced.

  In addition, since the ID notification tag 40 of this embodiment is installed on the ground, battery replacement work is easier than the data communication tag 10 installed in the manhole 1. That is, it can be said that reducing the power consumption of the data communication tag 10 in which the battery replacement is not easy in the manhole 1 is an extremely large effect as in the first embodiment.

FIG. 8 illustrates a configuration example of the data communication tag 10, the ID notification tag 40, and the reader 20 according to the third embodiment.
In FIG. 8, the tag 10 for data communication includes a data processing unit 11 that processes data input from the sensor 3 and generates a radio frame, and a transmission unit 12 that transmits the radio frame at a predetermined transmission cycle. The ID data of this radio frame is deleted as shown in FIG. 7, and the reader 20 cannot usually determine from which tag the data is transmitted.

  The ID notification tag 40 includes a data processing unit 41 that generates a total of 6 bytes (48 bits) of 1 byte of preamble, 4 bytes of ID data, and 1 byte of EOF (error detection), and a wireless frame with a predetermined transmission cycle. And a transmission unit 42 for transmission. The transmission cycle of the wireless frame transmitted from the data communication tag 10 and the transmission cycle of the wireless frame transmitted from the ID notification tag 40 are preferably the same, but they are not necessarily synchronized. .

  The reader 20 includes a receiving unit 24 that receives a wireless frame transmitted from the data communication tag 10 and a receiving unit 26 that receives a wireless frame transmitted from the ID notification tag 40. The radio frame transmitted from the data communication tag 10 is identified by setting the radio frame transmitted from the ID notification tag 40 to a different frequency, for example. The data processing unit 25 processes the wireless frame received by the receiving unit 26 to acquire the ID data of the tag notified from the ID notification tag 40 and receives the wireless data received by the receiving unit 24 based on the ID data of the tag. The sensor data of the frame is processed as being transmitted from the tag.

DESCRIPTION OF SYMBOLS 1 Manhole 2 Vehicle 3 Sensor 10 Tag 11 Data processing part 12 Transmission part 20 Reader 21 Position specification part 22 Storage part 23 Tag ID determination part 24 Receiving part 25 Data processing part 26 Receiving part 30 GPS apparatus 40 ID notification tag 41 Data processing Part 42 Transmitter

Claims (8)

An active tag communication method comprising: a tag that transmits a radio frame at a predetermined transmission cycle; and a reader that receives a radio frame transmitted from the tag, and performing communication between the fixedly arranged tag and the moving reader In
The radio frame of the tag is configured not to include ID data for specifying the tag,
The reader includes storage means for storing the tag position information and the ID data in association with each other, and refers to the storage means based on the reader position information detected using a predetermined position information detection means. An active tag communication method comprising: acquiring the ID data corresponding to the position information, specifying a tag that has transmitted the radio frame, and receiving the radio frame. An active tag communication method comprising: a tag that transmits a radio frame at a predetermined transmission cycle; and a reader that receives a radio frame transmitted from the tag, and performing communication between the fixedly arranged tag and the moving reader In
The radio frame of the tag is configured to include simple ID data of several bits or less that identify a small number of adjacent tags,
The reader includes storage means for storing the tag position information, the simple ID data, and ID data for identifying the tag in association with each other, and the reader position information detected using a predetermined position information detection means And referring to the storage means based on the received simple ID data of the radio frame, acquiring the ID data corresponding to the position information and simple ID data, identifying the tag that transmitted the radio frame, and An active tag communication method characterized by receiving and processing a frame. In the active tag communication method according to claim 1 or 2,
The active tag communication method, wherein the predetermined position information detecting means detects position information of the reader by receiving a GPS signal. An active tag communication method comprising: a tag that transmits a radio frame at a predetermined transmission cycle; and a reader that receives a radio frame transmitted from the tag, and performing communication between the fixedly arranged tag and the moving reader In
The radio frame of the tag is configured not to include ID data for specifying the tag,
Transmitting an ID notification radio frame including ID data of the tag from an ID notification tag arranged in the vicinity of the tag;
The reader receives a radio frame transmitted from the tag and an ID notification radio frame transmitted from the ID notification tag, acquires the ID data from the ID notification radio frame, and transmits the radio frame to the ID notification radio frame. An active tag communication method, comprising: identifying a transmitted tag and receiving the radio frame. An active tag communication system comprising: a tag that transmits a radio frame at a predetermined transmission cycle; and a reader that receives a radio frame transmitted from the tag, and performs communication between the fixedly arranged tag and the moving reader In
The tag is configured to transmit a radio frame that does not include ID data that identifies the tag,
The reader refers to the storage means based on the position information of the reader detected using a predetermined position information detection means, storage means for storing the tag position information and the ID data in association with each other, An active tag communication system comprising: processing means for acquiring the ID data corresponding to the position information, specifying a tag that has transmitted the radio frame, and receiving the radio frame. An active tag communication system comprising: a tag that transmits a radio frame at a predetermined transmission cycle; and a reader that receives a radio frame transmitted from the tag, and performs communication between the fixedly arranged tag and the moving reader In
The tag is configured to transmit a radio frame including simple ID data of several bits or less that identifies a small number of adjacent tags,
The reader includes storage means for storing the tag position information, the simple ID data, and ID data for identifying the tag in association with each other, reader position information detected using a predetermined position information detection means, and Based on the received simple ID data of the wireless frame, the storage means is referred to, the ID data corresponding to the position information and simple ID data is obtained, the tag that transmitted the wireless frame is specified, and the wireless frame is specified. An active tag communication system comprising: processing means for receiving and processing. The active tag communication system according to claim 5 or 6,
The active tag communication system, wherein the predetermined position information detecting means is configured to detect position information of the reader by receiving a GPS signal. An active tag communication system comprising: a tag that transmits a radio frame at a predetermined transmission cycle; and a reader that receives a radio frame transmitted from the tag, and performs communication between the fixedly arranged tag and the moving reader In
The tag is configured to transmit a radio frame that does not include ID data that identifies the tag,
An ID notification tag that is arranged in the vicinity of the tag and transmits an ID notification radio frame including ID data of the tag,
The reader receives a radio frame transmitted from the tag and an ID notification radio frame transmitted from the ID notification tag, acquires the ID data from the ID notification radio frame, and transmits the radio frame to the ID notification radio frame. An active tag communication system comprising processing means for specifying a transmitted tag and receiving the radio frame.

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