KR20080035385A - Method and system for real time locating and tracking - Google Patents

Abstract

An extended type real time locating system and a method thereof are provided to route data from an RFID tag wirelessly, to simplify installation of a system, and to get unrestricted to the number of devices such that it can enhance system scalability and variability. An extended type real time locating system comprises an RFID tag(210), plural RFID readers(220), an RFID sink(230) and a server(240). The RFID tag is attached at a target object to be located. The RFID readers perform radio communication with the RFID tag. The RFID sink performs radio communication with the RFID reader. The server performs wired or radio communication with the RFID sink and calculates a location of the RFID tag by storing and analyzing information on the RFID tag, the RFID readers and the RFID sink. The RFID readers are distributed in an area where the target object is positioned, and each RFID reader routes a transmission message to the RFID tag or the RFID sink via radio communication with another RFID reader.

Description

Scalable real-time location and tracking system and method {METHOD AND SYSTEM FOR REAL TIME LOCATING AND TRACKING}

1 is a block diagram of a conventional real-time positioning and tracking system (RTLS).

2 is an overall configuration diagram of an RTLS system according to an embodiment of the present invention.

3 is an operation explanatory diagram of an RTLS system according to an embodiment of the present invention.

4 is an operation flowchart of a tag according to an embodiment of the present invention.

5 is an operation flowchart of a reader according to an embodiment of the present invention.

6 is a flowchart illustrating an operation of a sink according to an embodiment of the present invention.

7 is an operation flowchart of a server according to an embodiment of the present invention.

8 is an overall configuration diagram of an RTLS system according to another embodiment of the present invention.

FIG. 9 illustrates time slots of a transmission signal during data routing between readers or between readers and sinks in the RTLS system of FIG. 8.

The present invention relates to a Real Time Locating Systems (RTLS) for identifying and tracking the location of an object in real time. In particular, an RFID (Radio Frequency IDentification) reader wirelessly communicates with other RFID readers and servers. It is possible to design a system with a large number of readers through communication, and to add a sink that acts as a relay between the RFID reader and the server. It's about RTLS.

Recently, interest and investment in RFID (Radio Frequency IDentification) and technology development are increasing. RFID technology attaches electronic tags to objects, wirelessly recognizes unique IDs of each electronic tag, and collects, stores, processes, and tracks the corresponding information to locate, remotely process, manage, and exchange information between objects. The technology of providing services. In particular, active RFID, which has its own internal battery and transmission device, can be used in various fields such as environmental monitoring, logistics, and medical care because it can transmit data over a long distance.

Currently, one of the active RFID applications is real-time positioning / tracking system (RTLS), which can confirm the location of a tagged object in real time. Here, the term “real time” means that the active RFID tag can calculate and confirm a position within 30 seconds after linking its information.

The RTLS is established by the international standard ISO / IEC 24730 based on the American standard ANSI / INCITS 371. It is divided into three parts: Application Programming Interface (API), 2.4 GHz RTLS, and 433 MHz RTLS. , Wireless standards, and so on. Among them, the 433MHz RTLS is a standard set for use in outdoor areas of more than 100m, and it is expected to save a lot of money by smoothly adjusting the whole system, especially in cargo containers, logistics, and distribution, and by knowing the flow path. .

1 is a block diagram of a typical RTLS system 100.

The tag 110 is an active RFID having a unique ID and is attached to an object (object, person, etc.) whose location is to be checked, and transmits its information (eg, battery level, temperature of the object, etc.) to the reader 120 at regular intervals. send. The reader 120 wirelessly communicates with the tag to give a command to the tag 110 or receive information from the tag 110 and transmit the information to the server 140. The server 140 collects, integrates and manages tag 110 information transmitted from the readers 120. The client 150 is a kind of application program that requests the server for necessary information according to a user's request and uses the obtained information according to an application environment.

The tag 110 and the readers 120 are connected by using a wireless interface, which is a protocol made for smooth wireless communication between both, and is currently defined for the 2.4 GHz and 433 MHz frequency bands. The readers 120 and the server 140 are connected using a wired interface such as serial or Ethernet. The server 140 and the client 150 are connected by using an API, which may use, for example, SOAP 1.1 or the like as a protocol made for consistent and smooth communication between the two.

In the conventional RTLS system 100, since the reader 120 and the server 140 exchange information using wired communication such as serial or Ethernet, installation of the reader becomes complicated and limitations of distance and number are inevitable. There is a problem that the system expansion or modification is not easy.

In addition, the existing system development cases related to RTLS are often independent systems lacking compatibility with standards, and there are many problems in compatibility with other application standards.

It is an object of the present invention to provide an RTLS system compatible with RTLS-related technical standards by configuring an RTLS system using an active RFID tag and a reader capable of bidirectional communication.

It is still another object of the present invention to provide a data routing function using wireless communication to a reader, and to provide a sink, which is a separate reader between a plurality of readers and a server, so that data from a tag can be wirelessly routed. It is easy to install and there is no limit on the number of devices, thus providing a scalable RTLS system with enhanced system scalability and variability.

It is still another object of the present invention to provide an RTLS system using a message format that can be effectively used for data transmission between readers or between reader and sink.

Still another object of the present invention is to provide an RTLS system capable of preventing collision between signals when transmitting signals from a plurality of readers.

It is still another object of the present invention to provide an RTLS system that can effectively identify and track the position of a tag even in an environment having readers arranged at intervals of 100 m or more using an active RFID device.

The present invention creates a sink with a reader using an RFID tag capable of bidirectional communication, attaches a tag to a target, collects location information through the reader, and transmits tag information using a data routing technique in wireless communication between the reader and the server. The server calculates the information of the tags sent from the reader and provides the function to check and track the exact location of the object.

An apparatus of the present invention for achieving the above objects and features, the extended real-time positioning and tracking system, comprising: at least one RFID tag attached to the positioning and tracking object; A plurality of RFID readers for wirelessly communicating with the RFID tag; At least one RFID sink for performing wireless communication with at least one RFID reader; And a server configured to perform wired communication with the RFID sink, and store and analyze information of the tag, reader, and sink to calculate the location of the tag, wherein the plurality of RFID readers are distributed in an area where the object is located. Each RFID reader is configured to route a transmission message to the tag or the sink through wireless communication with another RFID reader.

The method of the present invention for achieving the above objects and features, at least one RFID tag attached to the positioning object, a plurality of RFID reader for performing wireless communication with the RFID tag, at least one RFID reader and At least one RFID sink performing wireless communication, a server performing wired communication with the RFID sink, and storing and analyzing information of the RFID sink to calculate a position of the RFID tag in real time in a real-time positioning system A method for identifying the location of an object, the method comprising: (a) transmitting, at the server, a location request message of a target RFID tag to be located at least one RFID synchro; (b) transmitting, from the RFID sink receiving the location message, a location request message including its own information to at least one RFID reader; (c) transmitting, from the RFID reader receiving the message from the sink, a location request message with its information added to the target RFID tag; (d) broadcasting its information in a predetermined period in the target RFID tag receiving the location request message from the RFID tag; (e) receiving the information broadcasted from the target RFID tag in the plurality of RFID readers, and adding its own information to transmit a location information message to the RFID sink; (f) transmitting, to the server, a location information message added with its own information by the RFID sink receiving the location information message from the RFID tag; And (g) analyzing the location information from the RFID sink in the server to analyze the location of the target RFID tag.

Hereinafter, an embodiment of the present invention shown in the accompanying drawings will be described in detail for the present invention.

2 is a block diagram of an extended RTLS system according to an embodiment of the present invention.

The extended RTLS system 200 of FIG. 2 includes a tag 210, a reader 220, a sink 230, a server 240, and a client 250.

Here, since the client 250 is the same component as the conventional client 150 shown in FIG. 1 and uses the same API as the conventional case for the connection with the server 240, a description thereof will be omitted. .

The tag 210 is an active RFID tag that has a unique ID to distinguish each attached object, broadcasts its information around at regular intervals, and analyzes and executes a command of the reader transmitted from the reader 220. The tag 210 is roughly divided into a hardware part and a software part, and the hardware part basically includes an RF module including an RF chip for wireless communication with a processor performing an operation. In addition, the software portion is largely composed of a wireless protocol and an application program, which will be described later.

The reader 220 has a wireless communication function with the tag 210, the sink 230, and other readers 220 to relay communications between the components. Reader 220 also has a unique ID to distinguish it from other readers are installed at regular intervals, and holds information about their location. When the reader 220 receives the information broadcast by the tag 210, the information of the tag 210 and the signal strength information (hereinafter, 'received signal strength' or 'RSSI' (Received Radio Strength Indicator), and the reader 220 itself The information is transmitted to the sink 230, and when the information is received from the sink 230, it is transmitted to the tag 210. In particular, since the reader 220 according to the present invention can communicate wirelessly with other readers, the reader 220 may transmit information using a routing function even when it is far from the sink 230.

The hardware of the reader 220 includes a processor and an RF module, and the software is configured to include wireless protocols and applications. The reader 220 may be designed as an active RFID device of appropriate specification according to the specification of the RTLS system, but in the present embodiment, the reader 220 is configured to have the same hardware as the tag 210. If necessary, a serial controller or a USB controller may be added to support wired communication between the reader and the server used in the existing RTLS system. The software portion of the reader 220 will be described later.

The sink 230 serves as another leader that acts as a relay between the reader 220 and the server 240. The sink 230 has a unique ID and is installed in a place where it can be distinguished from other sinks 230 and readers 220 and communicate with one or more readers 220, and holds information about its location. . The sink 230 transmits the information to the server 240 when it receives the information from the reader 220 and transmits the information to the reader 220 when the information is received from the server 240. The sink 230 communicates using the wireless communication with the reader 220, and preferably communicates with the server 240 by using a wire such as serial or Ethernet. In some cases, the wireless communication is also possible.

The hardware of the sink 230 includes a processor and an RF module, and the software is configured to include wireless protocols and applications. The sink 230 may also be designed as an active RFID device with appropriate specifications according to the specifications of the RTLS system, but in the present embodiment, the sink 230 is configured to have the same hardware as the tags 210 and the reader 220 in principle. do. However, since the sink 230 generally needs to perform wired communication with the server 240, a serial controller or a USB controller should be provided for this purpose. The software portion of the sink 230 will be described later.

The server 240 receives a user's command to a small computer (or software application) with sufficient computing power and transmits the command to the reader 220 through the sink 230 or from the sink 230 through the reader 220. It analyzes the information about the received tag 210, calculates, stores and tracks the location of the tag 210, and displays the result information directly or through the client 150 in a graphic manner.

Now, the overall operation of the RTLS system according to an embodiment of the present invention shown in FIG. 3 will be described.

The RTLS system 300 of FIG. 3 includes at least one sink 330, at least one server 340, a plurality of tags 310, and a plurality of readers 320, each having a unique ID. 320 is disposed at predetermined intervals R to include a space in which tags 310 are located or moved. The tag 310 is attached to the object to be observed and broadcasts its information around at regular time intervals. The sink 330 that communicates with the server 340 by wire is located where communication with the one or more readers 320 is possible.

When the user wants to check the location and information of the tag 310 through the server 340, first, a command is given to the server 340, and the server 340 transmits the command to the sink 330. The command is transmitted via a wired network between the server 340 and the sink 330, and such wired networks and corresponding transmission protocols are variously known.

Subsequently, the sink 330 transmits the message transmitted from the server 340 to one or more readers 320 capable of transmitting the message, and the reader 320 receiving the message transmits the message transmitted from the sink 330 to all tags (around). 310 and the readers 320. Broadcasting refers to transmitting a message without specifically designating an address of a receiving device.

또는 그 이상인 것이 바람직하며, 이는 해당 태그(310)의 신호를 수신하는 리더의 수가 많을수록 위치 정밀도가 높아지기 때문이다. 한편, 태그(310)와 달리 리더(320)의 경우에는 리더(320) 간의 주파수 사용상의 충돌을 피하기 위해 신호 전송 거리가 최대

인 것이 바람직하며, 이에 대해서는 도 8과 관련하여 후술하기로 한다.The tag 310 receiving a message from the reader 320 communicating with itself analyzes it and broadcasts its information (eg, tag ID, manufacturer ID, etc.) around a predetermined time period. When the readers 320 are spaced apart by a distance R, the signal transmission distance of the tag 310 is

Or, it is preferable that the number is higher, because the higher the number of readers that receive the signal of the tag 310, the higher the position accuracy. On the other hand, unlike the tag 310, in the case of the reader 320, the signal transmission distance is maximum in order to avoid a collision in frequency usage between the readers 320.

It is preferable that this will be described later with reference to FIG.

The at least one reader 320 receiving the message from the tag 310 measures the received signal strength (RSSI) from the tag 310 and includes its own information (eg, reader ID, manufacturer ID, etc.) and information of the tag (ie, Message content and radio wave strength) from the tag to the sink 330. In this case, when direct communication is not possible because the distance between the reader 320 and the sink 330 is too long, the message is transmitted by using wireless communication using a data routing technique of the reader 320 and the sink 330. This will be described later.

The sink 330 receiving the message from the reader 320 transmits the information of the transmission reader 320 and its own information (eg, sink ID, manufacturer ID, etc.) to the server 340 connected by wire.

As described above, the tag 310 message information received by each reader 320 is all transmitted to the server 340 through the sink 330, and the server calculates the location of the tag 310 by combining them. Position calculation includes Time Difference of Arrival (TDOA) using message arrival time from tag 310 to each reader 320, and ROA (RSSI) using tag 310 message received signal strength (RSSI) at each reader 320. Known methods such as of Arrival Ranging) may be used, and the present invention has been described in the present specification by using RSSI and ROA as an example, but the present invention is not limited thereto.

Meanwhile, in the present embodiment, the format is determined according to ISO / IEC 24730-3, which is currently enacted with respect to the message format from the tag 310 to the reader 320 ('tag to reader message format') as follows.

Protocol ID Tag Status Packet Length Reader ID Tag Mfr. ID Tag ID Command Code Data CRC 0x40 2 bytes 1 byte 2 bytes 2 bytes 4 bytes 1 byte N bytes 2 bytes

In Table 1, Protocol ID is an identifier for identifying an RTLS system from other standards, and is defined as "0x40" among values between "0x40" and "0x4F" that can be used in an RTLS system. Reader ID, Tag Mfr. ID and Tag ID represent the reader 320 ID, the tag 310 manufacturer ID, and the tag 310 ID information, respectively. Command Code represents the current command code, Data represents the information according to the Command Code, CRC represents the CRC value for error checking of the message.

On the other hand, Tag Status is a field indicating the status of the tag 310, a mode indicating a response message type (i.e., whether it is a broadcast (broadcast) command or a point command), and whether the command received from the reader 320 is valid. It includes fields such as Ack, Tag Type indicating information on tag characteristics, and Service Bit indicating the battery status of a tag.

Meanwhile, the message format ('reader to tag message format') from the reader 320 to the tag 310 is also defined according to the above standard as follows.

Protocol ID Packet Options Tag Mfr. ID Tag ID Reader ID Command Code Data CRC 0x40 1 byte 2 bytes 4 bytes 2 bytes 1 byte N bytes 2 bytes

Protocol ID Packet Options Reader ID Command Code Data CRC 0x40 1 byte 2 bytes 1 byte N bytes 2 bytes

The message format of Table 2 is used when sending a point command when positioning is desired for one tag 310, and the message format of Table 3 is used when positioning is desired for a plurality of tags 310. This is used when transmitting a broadcast (broadcast) command. According to the type of Packet Option, transmission signal is classified into point method and broadcasting method. Tag Mfr. The ID and Tag ID fields are added or deleted.

Table 4 below shows a format used for transmitting a message from the reader 320 to the sink 330 (or another reader 320) ('leader to sink message format'). Since the RTLS standard does not define a communication message format in this case, the present invention will be defined and used as follows.

Protocol ID Command Type Packet Length Sender ID Receiver ID Destination ID Data CRC 0x42 1 byte 1 byte 2 bytes 2 bytes 1 byte N bytes 2 bytes

In Table 4, Protocol ID is an identifier for distinguishing an RTLS system from other standards, and arbitrarily defines “0x42” among values between “0x40” and “0x4F” that can be used in an RTLS system. Of course, other values within the allowable range may be used without departing from the RTLS standard.

The command type includes a field for distinguishing between point-type transmission and broadcast (broadcast) transmission, and may include a field for specifying an air interface protocol for compatibility and extension with other application standards. Upon receiving the message, the reader 320 or the sink 330 analyzes the command type to know the exact information of the transmission message.

Packet Length indicates the length of a data packet to be transmitted.

The Sender ID indicates a unique ID of the transmitting device (ie, the reader 320), and the Receiver ID indicates a unique ID of the receiving device (ie, the sink 330, etc.) located within the transmittable distance, and the Destination ID finally indicates the message. Indicates a unique ID of a target (ie, tag 310 or reader 320) to be transmitted.

In the extended RTLS system according to the present invention, since the distance between the reader 320 and the sink 330 is far from one hop communication, a message must be transmitted through other readers 320 between the two. You will use the message format as shown in Figure 4. For example, when communication is performed between the reader 320 and the sink 330 in one hop, the receiver ID and the destination ID may be set identically, and communication with the sink 330 is performed through the other readers 320 in multi-hop. If necessary, in order to use a routing technique, an ID of another reader 320 that directly receives a corresponding message is designated as a receiver ID, and an ID of the sink 330 is designated as a destination ID.

In this case, the tag 310 information (that is, the transmission message and the signal reception strength (RSSI) from the tag 310) is stored in the data field.

On the other hand, the message format when transmitting a message from the sink 330 to the reader 320 may use the same format as the format shown in Table 4. In this case, the Sender ID is a unique ID of a transmitting device (ie, the sink 330), and the Receiver ID is a unique ID of a receiving device (ie, the reader 330) located within a transmittable distance. Represents a unique ID of a transmission target (ie, tag 310). In addition, the Data field should include a message to be sent to the tag 310.

4 is an operation flowchart of a tag in an RTLS system according to an embodiment of the present invention.

When the tag 310 is powered on and starts to operate, the tag 310 waits for a wireless message from the outside and receives it (S410). When receiving a wireless message during operation, it is analyzed to see if it is transmitted from the reader 320 (S420). If it is not a message from the reader 320, it ignores and returns to the reception standby state (S410) again, and if it is a message sent to itself from the reader 320 for its information and commands from the reader 320. The processing result is broadcasted around at regular intervals (S430). Meanwhile, when the RTLS system 300 simultaneously performs a function according to an application standard other than RTLS as one RFID system, the tag 310 analyzes a message from the reader 320 to be a command according to another application standard. In this case, information suitable for the transmission may be transmitted. The same is true for other components such as the reader 320, the sink 330, and the server 340.

5 is a flowchart illustrating an operation of a reader in an RTLS system according to an embodiment of the present invention.

The reader 320 receives a wireless message from the outside when the power is supplied and starts the operation (S510). When the wireless message is received during operation, it is analyzed to determine whether it is from the tag 310, the sink 330, or the other reader 320 (S520, S550, and S570). If it is a message transmitted from the tag 310, the received signal strength (RSSI) is measured (S530), and the information of its own 320 and the tag 310 transmits to the sink 330 (S540). If it is a message transmitted from the sink 330 it transmits the information of itself 320 and the information of the sink 330 to the tag 310 (S560). If wireless communication with the sink 330 is not possible directly (ie, one-hop), the message is transmitted using the communication between the reader 320, so that if it is a message transmitted from another reader 320, The information and the information of the transmission reader 320 are transmitted to the sink 330 or the tag 310 which is the final destination (S580).

6 is a flowchart illustrating an operation of a sink according to an embodiment of the present invention.

The sink 330 waits for a wireless message and a wired message from the outside when the power is supplied and starts the operation (S610 and S630). For reference, in FIG. 6, the wired message is exemplarily represented as a universal asynchronous receiver transmitter (UART), which is a type of serial communication method commonly used. Wired and wireless messages may be received separately because message transfer protocols are different. If the message is received via wireless during operation, since it is a message from the reader 320, the information of the self 330 and the information of the transmission reader 320 are wired to the server 340 through a wire (S620). On the contrary, when the message is received through the wire, the message is transmitted from the server 340 to the reader 320 over the air (S640). Meanwhile, although only the case in which the sink 330 and the server 340 are connected by wires has been described, it is also possible to communicate wirelessly, which also does not depart from the scope of the present invention.

7 is an operation flowchart of a server according to an embodiment of the present invention.

The server 340 waits for a wired message from the outside when power is supplied and starts an operation (S710, S750). Message reception from the sink 330 and message reception from the server 340 are performed independently and independently. When receiving a message from the sink 330 stores the information on the tag 310 and the reader 320 and the sink 330 related to the transmission of the message (S720), and calculates the position of the tag 310 (S730) ), If necessary, shows the calculation result to the user (S740). If the user's command is received after generating a transmission message corresponding to the command (S760), and transmits the message to the sink 330 via a wire.

8 is an overall configuration diagram of a real-time location confirmation and tracking system according to another embodiment of the present invention.

In FIG. 8, the entire area including 36 leaders may be divided into, for example, four subregions A, B, C, and D of nine leaders. Each leader in a subzone is distinguished from other leaders by using a local ID that indicates its relative position within that subzone, instead of its own unique ID. Considering the total number of leaders and the number of leaders included in each subdivision, the local ID of each leader can be obtained through mathematical calculations.

For example, in the case of a subregion consisting of 9 leaders, each leader will have one of the local IDs (numbered by circles in FIG. 8) between 1 and 9, and thus will have a unique local ID within the subregion. The transmission distance of each tag is shown by the dotted line, and the local IDs of all readers within the transmission range of each tag have one of the values 1 to 9 without overlapping each other. In this environment, each reader transmits a message using its local ID information. In addition, as shown in Figure 9, for smooth transmission through the collision avoidance of the signal to divide the total transmission time into nine slots corresponding to the number of local ID, each reader in the slot corresponding to its own local ID It will send a message.

이하로 설정되어야 하며, 특히 최대치인

로 설정되는 것이 바람직하다. 예컨대, 소구역 A의 1번 리더의 전송 범위가

이면, 1번 리더의 전송 신호는 2, 5, 6번 리더에게만 수신되며, 소구역 A의 5번 리더의 경우는 1, 2, 3, 4, 6, 7, 8, 9번 리더에게 수신되며, 소구역 A의 9번 리더의 경우 소구역 A의 4, 5, 8번 리더와 소구역 B의 6, 7번 리더, 소구역 C의 2, 3번 리더 및 소구역 D의 1번 리더에게까지 신호가 수신된다. 이때 각 리더는 시분할다중접속방식(TDMA)에 따라 자신에게 할당된 시간 슬롯 구간(즉, 자신의 로컬 아이디와 동일한 시간 슬롯 구간)에만 신호를 전송하므로, 소구역 A의 9번 리더 신호 전송 시간 동안에는 전송 범위 내에 속하는 다른 리더의 신호 전송이 없으므로 전파충돌이 방지된다. 또한, 소구역 A, B, C, D의 9번 리더가 동일한 시간 슬롯에 신호를 전송하더라도 전파 전송 범위의 제한으로 인해 전파충돌이 방지되어 동시 전송이 가능하다. 이는, 각 태그(810)와 리더(820)의 전송 범위 내에 동일한 로컬 아이디를 가지는 리더가 하나만 존재하도록 전체 시스템에 설계되었기 때문이다.As described above, since only one reader having the same local ID exists in the transmission range of each tag, a message collision problem due to simultaneous transmission of the reader having the same local ID in each subregion can be avoided. To this end, when the distance between readers is R, the signal transmission range of the reader is

Should be set to below, especially the maximum

Is preferably set to. For example, the transmission range of leader 1 of subregion A is

In this case, the transmission signal of leader 1 is received only by readers 2, 5, and 6, and the leader 5 of subregion A is received by readers 1, 2, 3, 4, 6, 7, 8, and 9. For subregion A leader 9, signals are received from leaders 4, 5, and 8 of subregion A, leaders 6 and 7, of subregion B, leaders 2 and 3 of subregion C, and leader 1 of subregion D. In this case, each reader transmits a signal only in a time slot section allocated to itself according to time division multiple access (TDMA) (that is, a time slot section identical to its local ID). Since there is no signal transmission from other readers within range, propagation collisions are prevented. In addition, even if the readers 9, 9, of the small zones A, B, C, and D transmit signals in the same time slot, radio waves are prevented due to the limitation of the radio wave transmission range, thereby enabling simultaneous transmission. This is because the entire system is designed such that only one reader having the same local ID exists within the transmission range of each tag 810 and reader 820.

) 내에 싱크(830)가 존재하지 않을 경우 리더(820) 간의 통신을 이용한다. 이러한 리더(820)에서 싱크(830)까지의 메시지 전송 순서는 다음과 같다.Again in FIG. 8, when the reader 820 sends a message to the sink 830, the propagation reach of the reader 820 (eg,

If the sink 830 does not exist in the ()) communication between the reader 820 is used. The message transmission order from the reader 820 to the sink 830 is as follows.

First, within subzone A, the readers, except for the leader with local ID 9 (that is, the last leader in the message delivery sequence), receive their frequency usage time (ie, their local ID when receiving information from the tag). Slot), the message is sent to the reader with the next local ID number. For example, when reader 1 of subregion A of FIG. 8 receives information from a tag, the reader 1 transmits a message stored in reader 2 at its frequency use time (ie, slot 1, see FIG. 9). Subsequently, reader 2 transmits the corresponding message to reader 3 in slot 2, and in turn, transmits 3 to 4 and finally transmits to reader 9. In this case, the receiver ID of the 'reader to sync message format' defined in [Table 4] specifies the unique ID of the next reader to receive the message, and the destination ID specifies the unique ID of the reader having the local ID of 9 to transmit the message. To be possible.

The first process (i.e. data routing in subzone A) allows a leader with a local ID of 9 to gather information from several readers in the region, which is then used for its frequency usage (i.e. slot 9). ) Is transmitted to the sink 830 within its propagation range or to the reader closest to the sink (ie, the reader having the local ID of subregion B of 9). For example, if there is information to be transmitted to the sink 830 in the zone A of FIG. 8, the reader 9 searches the routing table and transmits the stored message to the reader 7 of the zone B closest to the sink. In this case, a unique ID of a reader (ie, leader 7 of subregion B) that receives a message is designated as a receiver ID of 'reader to sink message format' defined in [Table 4], and a unique ID of the sink 830 is designated as a destination ID. To allow the message to be sent at the shortest distance. Through this process, the transmission process in subregion A within one transmission time (that is, the time taken to deliver the tag message from the leader 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 9) within the corresponding subregion. Is completed and the message is forwarded to subzone B.

As a third process, a reader receiving a message transmitted to the sink 830 (ie, leader 7 of the small area B) uses the information in the routing table at the time of use of the frequency to sink (830) in its propagation range. Or it transmits to the reader closest to the sink (830). For example, if there is information to be transmitted to the sink 830 in the zone B of FIG. 8, the reader # 7 searches the routing table and transmits a message to the reader 8 closest to the sink 830. In this way, the 8th reader is transmitted to the 9th reader, and the 9th reader is transmitted to the sink 830, respectively. At this time, in case of the 9th reader, the unique ID of the sink 830 is transmitted to the receiver ID and the destination ID of the “leader to sink message format” defined in [Table 4].

On the other hand, in order to minimize the frequency collision between the readers, it is preferable that the division of time slots for the message shown in FIG. 9 be equally applied to all readers.

On the other hand, the tag 810 uses a message size of at least 15 bytes up to 20 bytes when blinking (or transmitting) its information, and the reader uses a message size of 40 bytes or less when transmitting its information and information of the tag. Use size When all readers in a region received information from a tag, ideally a reader with a local ID of 9 would have a total of 360 bytes of transmitted messages. In the standard, the transmission time of one byte is 326us, so the message transmission time of 360 bytes is 117.36ms. At this time, since the preamble time for synchronization during data transmission between the readers is 1296us, the total of the message transmission time is 118.656ms. Therefore, one slot of the total time slots for the use of radio frequency should use more than 118.656ms.

Although the present invention has been described above according to a preferred embodiment of the present invention, the scope of the present invention is not limited to the above embodiments or the accompanying drawings, and is not limited to the scope of the present invention as set forth in the appended claims. Various variations are possible in.

According to the present invention, an RTLS system compatible with RTLS-related technical standards is provided by configuring an RTLS system using an active RFID tag and a reader capable of bidirectional communication.

In addition, according to the present invention, by providing a data routing function using a wireless communication to the reader, and providing a sink, which is a separate reader between the plurality of readers and the server, it is possible to wirelessly route data from the tag, It is easy to install and there is no limit to the number of devices, so a scalable RTLS system is provided that enhances the scalability and variability of the system.

In addition, according to the present invention, there is provided an RTLS system using a message format that can be effectively used in data transmission between readers or between reader and sink.

In addition, according to the present invention, there is provided an RTLS system that can prevent a collision between signals when transmitting signals from a plurality of readers.

In addition, according to the present invention, there is provided an RTLS system that can effectively identify and track the position of a tag even in an environment having readers arranged at intervals of 100 m or more using an active RFID device.

Claims (11)

In real time location and tracking system, At least one RFID tag attached to a positioning and tracking object; A plurality of RFID readers for wirelessly communicating with the RFID tag; At least one RFID sink for performing wireless communication with at least one RFID reader; And The server performs wired or wireless communication with the RFID sink, and stores and analyzes information of the tag, reader, and sink to calculate a location of the tag. The plurality of RFID readers are distributed and disposed in an area in which the object is located, and each RFID reader routes and transmits a transmission message to the tag or the sink through wireless communication with another RFID reader. system. The method of claim 1, The RFID tag is an active RFID device capable of bidirectional communication, and the RFID reader is an active RFID device capable of bidirectional communication, and measures the signal reception strength from the RFID tag, and the signal reception strength, the RFID tag information and its own information. Real-time positioning and tracking system, characterized in that for transmitting to the RFID sink. The method of claim 2, And a message format of a transmission signal used for wireless communication between the RFID reader or wireless communication between the RFID reader and the RFID sink includes a Sender ID, a Receiver ID, and a Destination ID. The method of claim 3, wherein The entire area where the object is located is divided into a plurality of major zones, the RFID sink is assigned to each major zone one by one, and each of the major zones is further divided into a plurality of subzones, and the plurality of RFID readers are unique in each subzone. Real-time positioning and tracking system, characterized in that arranged in each sub-region to have a local ID. The method of claim 4, wherein The signal transmission range of the RFID tag is set not to include two different readers having the same local ID over different subregions, and the transmission signal used for the wireless communication is the number of the RFID readers disposed in each subregion. And the same number of time slots as each RFID reader transmits the transmission signal in a time slot section having the same number as its local ID. The method of claim 5, wherein The plurality of RFID readers are arranged at equal intervals R in the small region, and the signal transmission range of the RFID tag is

The signal transmission range of the RFID reader is above R.

Hereinafter, in the signal transmission range of one RFID reader, only the RFID readers having a local ID different from the RFID reader are arranged. The method of claim 6, The RFID tag, the RFID reader and the RFID sink are configured to include the same RF module. At least one RFID tag attached to a positioning object, a plurality of RFID readers for wireless communication with the RFID tag, at least one RFID sink for wireless communication with at least one RFID reader, and the RFID sink A method for identifying a location of an object in real time in a real-time positioning system that performs a wired or wireless communication with the server, and stores and analyzes information of the RFID sink to calculate a location of the RFID tag. (a) transmitting, at the server, a location request message of a target RFID tag to which at least one RFID sync is located; (b) transmitting, from the RFID sink receiving the location message, a location request message including its own information to at least one RFID reader; (c) transmitting, from the RFID reader receiving the message from the sink, a location request message with its information added to the target RFID tag; (d) broadcasting its information in a predetermined period in the target RFID tag receiving the location request message from the RFID tag; (e) receiving the information broadcasted from the target RFID tag in the plurality of RFID readers, and adding its own information to transmit a location information message to the RFID sink; (f) transmitting, to the server, a location information message added with its own information by the RFID sink receiving the location information message from the RFID tag; And (g) analyzing the location information from the RFID sink in the server to analyze the location of the target RFID tag. The method of claim 8, The step (c) is the step of transmitting the location request message to the target RFID tag via at least one other RFID reader in one RFID reader. The method of claim 9, The step (e) is a step of transmitting the location information message to the RFID sink via at least one other RFID reader in one RFID reader. The method according to claim 9 or 10, The message format of the transmission signal used in the wireless communication between the RFID reader or the wireless communication between the RFID reader and the RFID sink includes a Sender ID, a Receiver ID, and a Destination ID.

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