KR100660150B1 - Apparatus for sensing rfid tag using multiple antenna and method therefor - Google Patents

Abstract

The present invention relates to a reader device and a method for detecting an object having a radio frequency identification (RFID) tag and mixed in separate spaces and large areas. The apparatus for detecting a radio frequency identification tag includes a plurality of connection control devices connected to a plurality of antennas respectively covering a plurality of areas, and connected and connected to the connection control devices to reproduce and restore signals of the antennas. An RFID reader for identifying areas and detecting a radio frequency identification (RFID) tag provided on an object within the areas, and a central controller connected to the RFID reader to recognize the RFID tag and to control the connection control devices. It is characterized by. The present invention has the effect of reducing the equipment and installation costs due to RFID readers and extending the actual receiving distance.

RFID TAG, RFID READER, MULTIPLE ANTENNA, VECTOR MODULATOR, LNA

Description

Apparatus and method for detecting radio frequency identification tag using multiple antennas {APPARATUS FOR SENSING RFID TAG USING MULTIPLE ANTENNA AND METHOD THEREFOR}             

1 is a diagram schematically illustrating a parking space in which an RFID reader having a plurality of antennas is installed according to an embodiment of the present invention.

2 is a diagram illustrating a hierarchical structure of connection control devices according to another embodiment of the present invention.

3 is a diagram schematically illustrating an indoor space in which an RFID reader having a plurality of antennas is installed according to another embodiment of the present invention.

4 is a structure of an RFID tag system including a plurality of readers according to another embodiment of the present invention.

5 is a structure of an RFID reader according to a preferred embodiment of the present invention.

6 is a signal flow diagram illustrating communication between an RFID reader and a central controller in accordance with a preferred embodiment of the present invention.

7 is a diagram illustrating a protocol structure of event information transmitted from an RFID reader to a central controller according to a preferred embodiment of the present invention.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to the locating of an object, in particular an object having a Radio Frequency Identification (RFID) tag and intermingled in separate spaces and large areas. It relates to a reader device and a method for tracking the movement by sensing the position of the.

As a technology for easily identifying the position of a desired object, such as a child or a car, in a space spread over a large area, a satellite positioning system (GPS system) or a wireless mobile communication system is commonly used. The GPS system is easy to provide location and time information of the vehicle and is very effective when used outdoors, and is particularly useful for checking a stationary object. However, GPS receivers are very expensive and have high maintenance costs, and the accuracy of positioning is remarkably poor in indoors and undergrounds where satellite signals cannot be received. The mobile communication system can determine the location by installing only the base station not only outdoors but also indoors or underground, and the equipment for transmitting / receiving is cheaper than the GPS system. However, the location information has a problem that the error range is very large as the radius of the base station, maintenance costs such as communication fees, and data loss is relatively large.

As a technology to satisfy these requirements, a contactless RFID tag system has been developed that can be used simply and non-permanently in a limited area such as an apartment building premises or an underground parking lot. The RFID tag system attaches or mounts an RFID tag having a small antenna and an integrated circuit (hereinafter referred to as "IC") to an object of location tracking, and from the RFID tag in response to a signal transmitted from the RFID reader. It detects the position of the object and tracks its movement according to the incoming signal. This RFID tag system is very useful in that it is robust, can be reused repeatedly, and can transmit and receive a lot of information quickly and accurately without contact.

However, the RFID tag system using a radio frequency signal in the 900MHz band usually has a limit of recognition distance due to its frequency characteristics, and the transmission output is rejected by the noise of the receiver in the RFID reader to further reduce the reception distance. Moreover, in limited areas such as apartment buildings or underground parking lots where RFID tag systems are mainly used, radio signals may be shielded or disconnected, and a large number of RFID readers may be used to detect mixed RFID tags in separated areas and large areas. They have the problem that they still require a lot of installation costs.

Accordingly, an object of the present invention, which is designed to solve the problems of the prior art operating as described above, provides an apparatus and method for detecting an RFID tag using multiple antennas to detect RFID tags in a separated space and a large area. It is.

Another object of the present invention is to provide an apparatus and method for detecting an RFID tag that distinguishes areas by each of multiple antennas for detecting RFID tags.                         

Still another object of the present invention is to provide an apparatus and method for detecting an RFID tag, which improves a reception distance for detecting RFID tags.

Still another object of the present invention is to provide an apparatus and method for detecting an RFID tag, in which a transmission output for detecting the RFID tags is prevented from acting as noise at the receiving end.

In order to achieve the above object, an embodiment of the present invention provides a device for detecting a radio frequency identification tag.

A plurality of connection control apparatuses connected to a plurality of antennas respectively covering a plurality of regions, for reproducing and restoring signals of the antennas;

At least one RFID reader connected to the connection control devices to identify the areas and to sense a radio frequency identification (RFID) tag provided to an object in the areas;

And a central controller connected to the RFID reader to recognize the RFID tag and to control the connection control devices.

Another embodiment of the present invention, in a method for detecting a radio frequency identification tag,

Receiving tag information from a radio frequency identification (RFID) tag provided to an object in the areas by any one of a plurality of antennas respectively covering a plurality of areas;

And reporting the tag information by adding the area information of the antenna that has received the tag information and the time information when the tag information is received.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

The present invention to be described below relates to a sensing apparatus of an RFID tag for sensing an RFID tag provided in an object. In particular, the present invention is to detect RFID tags mixed in a large space by using a few RFID readers and a plurality of antennas. To this end, the present invention provides a multi-antenna connection control apparatus that can be connected to a plurality of antenna array using the antenna terminal provided in the RFID reader. The connection control device includes a booster and the like to provide a function of reproducing and restoring an RF signal.

1 is a schematic diagram of a parking space divided into a plurality of areas according to a preferred embodiment of the present invention.

Referring to FIG. 1, the parking space 13 is divided into a plurality of zones. Antennas 29, 31, 34, 36, 39, 41, 44, 46, 49, and 51 connected to the connection control devices 32, 37, 42, 47, and 52 are disposed in the respective areas. Each of the antennas has a unique area index corresponding to that area. Here, only two antennas 29, 31, 34, 36, 39, 41, 44, 46, 49, and 51 are connected to each of the connection control devices 32, 37, 42, 47, and 52. In reality, each of the connection control devices 32, 37, 42, 47, and 52 has two or more (for example, depending on the structural topographical characteristics of the covered areas and the number of antenna connection tabs provided). Up to 10 antennas). Here, each of the regions means a range within a limit in which signals of the antennas 29, 31, 34, 36, 39, 41, 44, 46, 49, and 51 are transmitted and received.

The connection control devices 32, 37, 42, 47, and 52 are connected to a central RFID reader 22 via RF lines 56, and the RFID reader 22 communicates with the central controller 23. Tag information of RFID tags located in the areas is obtained. The RFID tag 26 is provided in an object such as an automobile 24 and its own in response to a signal transmitted from the antennas 29, 31, 34, 36, 39, 41, 44, 46, 49, and 51. The response signal including the tag information is transmitted. The tag information may include a state of the opening / closing of the door or the switch and the detection of the pressure according to the type or use of the object to which the RFID tag is attached.

In FIG. 1, the connection control devices are directly connected to the RFID reader, but in another embodiment, the connection control devices are hierarchically connected using an uplink terminal. Here, hierarchically connected means that the lower connection control device is connected to the RFID reader through the upper connection control device.

2 illustrates a hierarchical structure of connection control apparatuses according to another embodiment of the present invention.

As shown in the drawing, N connection control devices 110, 120, and 130 are hierarchically connected to the RFID reader 100. Each of the connection control devices 110, 120, and 130 is connected to antenna arrays 112, 122, and 132, each of which includes a plurality of antenna elements. A terminal TERM is connected to a specific antenna tap of the last connection control device 130. The connection control device 130 that detects the terminal device transmits antenna tap information connected to the terminal device and the antenna array 132 to the RFID reader 100, and similarly, other connection control devices 110 and 120. Also, the antenna tap information of the antenna arrays 112 and 122 connected to it is transmitted to the RFID reader 100. Then, the RFID reader 100 adjusts the RF output by matching the overall impedance according to the antenna tap information. In order to exchange such control information, the RFID reader 100 and the connection control devices 110, 120, and 130 have a separate programmable logic interface (PLC) interface in addition to an RF line for transmitting and receiving an RF signal.

3 is a schematic diagram of an indoor space in which an RFID reader having a plurality of antennas is installed according to another embodiment of the present invention.

Referring to FIG. 3, the indoor space 90 refers to a user's home or office and is divided into a plurality of zones separated by walls or partitions. Antennas 68, 70, 71, 74, 76, 78 and 80 connected to the connection control devices 64 and 66 are disposed in the respective areas, each of which has a unique area corresponding to the corresponding area. Has an index Here, the connection control device 64 is connected to the four antennas 68 to 74 and the next connection control device 66, and the connection control device 66 is connected to the three antennas 76 to 80. Here, each antenna senses RFID tags (not shown) located within an area of a corresponding range and receives the tag information.

The RFID tags are installed in windows, doors, gas valves, electrical switches, and the like to transmit the state information on the opening / closing to the tag information, or installed on the floor or the wall to transmit the state information about the pressure to the tag information. In other cases, the RFID tags may be used for checking the storage of valuables and the like or for identifying the location of a desired object. The tag information is collected by the RFID reader 62 and reported to the central controller 60. The central controller 60 collects, manages, and analyzes the tag information, and notifies the emergency alarm to a user's mobile phone or terminal which is set in advance when deemed necessary.

As an embodiment described above, the RFID reader is only functionally separated from the central controller, and is spatially and structurally identical. In another embodiment, the central controller is connected to a plurality of RFID readers, and the central controller and the plurality of RFID readers are spatially and structurally separated.

4 illustrates a structure of an RFID tag system including a plurality of readers according to another embodiment of the present invention.

Referring to FIG. 4, the RFID readers 210 and 220 communicate with the central controller 100 and are connected to N connection control devices 230, 232, 234, and 222. That is, the first RFID reader 210 is connected to the N connection control devices 230, 232, and 234, and the second RFID reader 220 is connected to the other connection control device 222. In the case of the first RFID reader 210, each of the connection control devices 230, 232, and 234 is connected to the first RFID reader 210 in a hierarchical structure, and also includes a plurality of antennas 240, 242, and 244. , 246, 248, 250). In detail, the first connection control device 230 is connected to the M antennas 240, 242, and 244, and the Nth connection control device 234 is connected to the K antennas 246, 248, and 250.

RF transmission signals from the RFID readers 210 and 220 are transmitted to the connection control devices 230, 232, 234, and 222, and are transmitted to the respective areas by the antennas 240 to 250. Since the RFID tag 252 is adjacent to the antenna # 1-2 242, the RFID tag 252 includes tag information for the RFID tag 252 in response to the transmission signal transmitted from the antenna # 1-2 242. Send a response signal. Then, the antenna # 1-2 242 transmits the response signal from the RFID tag 252 to the first connection control device 230, and the first connection control device 230 removes the response signal. 1 transfers to the RFID reader 210.

5 shows the structure of an RFID reader according to a preferred embodiment of the present invention.

Referring to FIG. 5, the RFID reader 300 transmits and receives an RF signal through a transmit / receive antenna array 310 that is connected or directly connected through connection control devices (not shown). The transmission signal generated from the transmitter 360 passes through the transmission path 322 and is transmitted to the antenna 310 by the duplexer 320. The received signal is transmitted to the reception path 324 by the duplexer 320. The received signal transmitted to the reception path 324 first reaches the vector modulator 330. The vector modulator 330 detects the noise signal induced by the transmission signal from the received signal, shifts the phase of the detected noise signal by 180 degrees, and adds the noise signal from the received signal again. Remove A low noise amplifier (hereinafter referred to as "LNA") 340 amplifies the output signal of the vector modulator 330 and extends it to the receiver 350 to extend the reception distance.

Response signals from the connection control devices are carried in a unique time domain assigned by the central controller so that they can be identified by the RFID reader. That is, the connection control devices include a time division device having a capacity equal to the number of antenna taps registered in advance, and a switch applying an addressing polling technique to communicate with the RFID reader through time division multiplexing. The time division apparatus time-division multiplexes and transmits signals received through the plurality of antennas to the RFID reader, and the switch distributes and transmits a signal from the RFID reader to one of the plurality of antennas. The RFID reader (especially the receiver) identifies an area where the RFID tag is detected according to the temporal arrangement of response signals received from the connection control devices, checks the system time at which the response signal is received, and checks the tag information of the RFID tag. Notify the central controller of area information and time information.

As a specific example, the RFID reader periodically transmits transmission signals to respective antennas of the connection control devices under the control of the central controller. When a response signal corresponding to a transmission signal transmitted to a specific antenna is received through one of the connection control devices, the RFID reader detects tag information included in the response signal and an area corresponding to the specific antenna in the tag information. Give information and time information and report it to the central controller. In another embodiment, each antenna of the connection control devices transmits periodic transmission signals and transmits response signals corresponding to the transmission signals to the RFID reader through the corresponding connection control device in the allocated time domain. The RFID reader recognizes area information according to the time domain in which the response signal is received, and adds area information and time information corresponding to a specific antenna that sent the response signal to tag information included in the response signal to the central controller. report.

6 is a signal flow diagram illustrating communication between an RFID reader and a central controller according to a preferred embodiment of the present invention.

Referring to FIG. 6, when there is no event, as shown in step 406, the RFID reader 402 and the central controller 404 perform a keeping alive check to determine whether there is an error in communication between them. do. When the RFID tag is detected by any one of the plurality of antennas and the response signal is transmitted to the RFID reader 402 through the corresponding connection control device as in step 408, the RFID reader 402 is the central controller 404 in step 410. Send event information to. An example of the protocol structure of the event information is shown in FIG.

Referring to FIG. 7, the event information 500 is transmitted by being surrounded by a start of transmission (STX) field 502 and an end of transmission (ETX) field 512 and indicating a tag detection time. (T) field 504, an area (Z) field 506 indicating a tag detection location, an event (E) field 508 indicating a type and status of a tag, and a cyclic redundancy check (CRC) code for error correction ( 510). Here, the event field includes tag information of a corresponding RFID tag, and the tag detection time means a system time when the tag information is received by the RFID reader.

The event information 500 configured as described above enables time synchronization, sequential polling information collection, and asynchronous information collection.

The central controller identifies the RFID tag according to the tag information. If the tag information cannot be understood, the central controller checks the tag information in association with an RFID naming center and determines the state information of the object with the RFID tag.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.                     

The present invention reduces the cost of equipment and installation due to RFID readers by detecting RFID tags mixed in separated spaces or large areas using a few RFID readers. In addition, the present invention solves the problem that the transmission output acts as a noise of the receiver to cause the loss of the received signal, and has the effect of amplifying the actual receiving distance by extending the received signal.

Claims (7)

delete In the detection device of the radio frequency identification tag, A plurality of connection control apparatuses connected to a plurality of antennas respectively covering a plurality of regions, for reproducing and restoring signals of the antennas; At least one RFID reader connected to the connection control devices to identify the areas and to sense a radio frequency identification (RFID) tag provided to an object in the areas; A central controller connected to the RFID reader to recognize the RFID tag and to control the connection control devices, The connection control device, The sensing device is connected to the RFID reader in a hierarchical structure, and an end device is connected to the antenna tab of the last connection control device of the hierarchical structure. In the detection device of the radio frequency identification tag, A plurality of connection control apparatuses connected to a plurality of antennas respectively covering a plurality of regions, for reproducing and restoring signals of the antennas; At least one RFID reader connected to the connection control devices to identify the areas and to sense a radio frequency identification (RFID) tag provided to an object in the areas; A central controller connected to the RFID reader to recognize the RFID tag and to control the connection control devices, Each of the connection control device, A time division apparatus for time division multiplexing and transmitting response signals received through the plurality of antennas to the RFID reader; And a switch configured to distribute and transmit a transmission signal from the RFID reader to one of the plurality of antennas. In the detection device of the radio frequency identification tag, A plurality of connection control apparatuses connected to a plurality of antennas respectively covering a plurality of regions, for reproducing and restoring signals of the antennas; At least one RFID reader connected to the connection control devices to identify the areas and to sense a radio frequency identification (RFID) tag provided to an object in the areas; A central controller connected to the RFID reader to recognize the RFID tag and to control the connection control devices, The RFID reader, Area information indicating the antenna that has received the response signal when the transmission signal for detecting the RFID tag is transmitted by the antennas and a response signal including tag information of the RFID tag is received in response to the transmission signal And time information indicating a system time of receiving the response signal is added to the tag information and reported to the central controller. The method of claim 1, wherein the RFID reader, A duplexer for connecting the plurality of antennas to a transmission path and a reception path by connecting to the plurality of antennas directly or through the connection control devices; A transmitter connected to the transmission path of the duplexer and transmitting a transmission signal for detecting the RFID tag; A vector modulator connected to the reception path of the duplexer to receive a response signal including tag information of the RFID tag and to remove noise induced in the response signal by the transmission path; A low noise amplifier for amplifying the output signal of the vector modulator; And a receiver configured to detect the tag information from an output signal of the low noise amplifier. In the method for detecting a radio frequency identification tag, Receiving tag information from a radio frequency identification (RFID) tag provided to an object in the areas by any one of a plurality of antennas respectively covering a plurality of areas; And reporting the tag information by adding area information of the antenna that has received the tag information and time information when the tag information is received. The method of claim 6, wherein the receiving process And transmits a transmission signal for detecting the RFID tag by the plurality of antennas, and receives a response signal including the tag information from one of the plurality of antennas in response to the transmission signal. The method.

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