KR100958238B1 - RF ID System - Google Patents

Abstract

According to the present invention, an RFID reader broadcasting a collection command in a 433 MHz active RFID system conforming to the ISO / IEC 18000-7 specification can specify a tag classification to respond to the command. Responding only when the RFID reader belongs to the classification designated by the RFID reader reduces collisions between RFID tags that competitively respond to the RFID reader's collection commands, so that the collection process can be performed more quickly.

RF ID, Collection, Collision, Slot, Field, Identification (AFI)

Description

RF ID System {Radio Frequency Identification System}

The present invention relates to an RFID ID system, and in particular, an RFID reader broadcasting a collection command can specify a tag classification to respond to the command, and RFID tags receiving the collection command are assigned to a tag classification designated by the RFID reader. By responding only if it belongs, it is possible to reduce collisions between RFID tags that competitively respond to a collection command.

Referring to FIG. 1, the RFID (RFID) system includes an RFID reader 11 and an RFID tag 12, and the RFID reader 11 transmits an RF signal to the RFID tag 12. When sending a query message to the RFID tag 12 sends a response message to the query message.

Meanwhile, in the 433 MHz active RFID system conforming to the air interface standard ISO / IEC 18000-7, the RFID reader 11 performs a collection process to collect information of surrounding RFID tags.

During the collection process, an RFID reader (also called an interrogator 11) collects all RFID tag information within a communication range by broadcasting a collection command, and then performs point-to-point (P2P) communication with a specific RFID tag.

In this collection process, slot collisions inevitably occur because neighboring RFID tags must respond with limited time slots. In particular, since the RFID tags required by the RFID reader 11 as well as all the surrounding RFID tags respond to the collection command, collisions have to occur more frequently. To avoid such slot collisions, various complicated communication algorithms and statistical slot allocation probabilities are being studied.

A collection process will be described with reference to FIG. 2.

When the RFID reader 11 broadcasts a collection command, all RFID tags Tag # 1 to #k within the communication range respond to this command to assign their tag IDs to the RFID reader 11. To send). At this time, all the RFID tags that have received the collection command of the RFID reader 11 generate random values and allocate time slot numbers according to the random values, and the corresponding delay time (assigned slot number * delay time per slot). At the last time, each response message is transmitted to the RFID reader 11.

As such, collision arbitration uses a mechanism that allocates the transmission time of each RFID tag to a slot within a specific collection round (the size of a window). The collection round is divided into several slots and the minimum window size to allocate slots is 57.3 ms.

On the other hand, the RFID reader 11 detects a collision with respect to responses from two or more RFID tags. That is, collisions are detected by detecting contention or invalid cyclic redundancy check (CRC) in a contention resulting from multiple RFID tag responses. The RFID reader 11 then records the collision and continues to listen for the response of the new RFID tag in subsequent time slots.

When the collection round is completed, the RFID reader 11 sends a sleep command to all RFID tags collected during the previous collection round. The tag receiving the sleep command moves to sleep mode and does not participate in subsequent collection rounds.

In FIG. 2, Tag # 1 and Tag #k responded normally, and Tag # 2 and # 3 did not respond normally due to a collision. Accordingly, after the collection round is completed, Tag # 1 and #k are in sleep mode. The state entered is shown.

The RFID reader 11 now immediately starts the next collection round by sending back a collection command. This process continues until no new RFID tags are detected in the next three collection rounds. Thereafter, the RFID reader 11 performs P2P communication with a specific RFID tag.

As described above, in the conventional collection process, slot allocation conflicts frequently occur because all RFID tags existing within the communication range of the RFID reader 11 participate in the collection round. Accordingly, the RFID reader 11 has a problem of performing a larger number of collection rounds in order to recognize RFID tags not recognized due to collision.

Therefore, the present invention has been made to solve the above problems, in the 433MHz active RFID system conforming to the ISO / IEC 18000-7 standard, not all RFID tags participate in the collection round, but only RFID tags of a specific classification desired by the user. The purpose of the present invention is to provide an RFID ID system that can reduce the probability of slot collision by allowing this to participate.

In order to achieve the above object, the RFID reader of the RFID ID system according to the present invention, when transmitting a Collection command to the RFID tag, the tag with the Application Family Identifier (AFI) in the 'Command Type' field of the message format A memory address in which information indicating division and an AFI value are stored is set, and an AFI value of a response target tag is set and broadcast in the 'Parameters' field.

In addition, the RFID tag of the RFID ID system according to the present invention accesses the data of the memory address set in the received message when the message received from the RFID reader indicates that the tag is classified by the AFI. And to respond to the collection command only when the corresponding data is equal to the AFI value of the response target tag set in the received message.

Information indicating that the tag is classified by the AFI is set in the most significant bit of the 'Command Type' field, and the memory address in which the AFI value is stored is set to the fourth to seventh bits of the 'Command Type' field. Can be configured to use.

The memory address in which the AFI value is stored may be configured to set an address '0x18' of 'bank01' in a bank of the RFID tag memory.

The AFI value of the response target tag may be configured to be set to the least significant byte of the 'Parameters' field.

The RFID tag may be configured to always respond to the collection command when the message received from the RFID reader is not indicated to classify the tag as the AFI.

According to the present invention, in the 433 MHz active RFID system conforming to the ISO / IEC 18000-7 standard, a response collision occurring when the RFID reader collects a plurality of RFID tag information can be reduced.

Thus, the RFID reader can quickly obtain the information of the RFID tag without unnecessarily increasing the window size. In particular, if the classification information of the RFID tag to participate in the collection process is set to the international standard classification code system, it can cope with different code systems defined in the future.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 shows a message format directed to an RFID tag in the ISO / IEC 18000-7 protocol, (1) shows a message format directed from an RFID reader to an RFID tag, (2) shows a 'Command Type' field format, and (3) Collection command format.

The format of the message from the RFID reader to the RFID tag is 1 byte of 'Command Prefix' field, 1 byte of 'Command Type' field, 3 bytes of 'Owner ID' field, 4 bytes of 'Tag ID' field, 2 bytes of ' It consists of an Interrogator ID 'field, a 1-byte' Command Code 'field, an N-byte' Parameters' field, and a 2-byte 'CRC' field. At this time, the least significant bit (bit 0) of the 1-byte 'Command Type' field is used to indicate whether or not 'Owner ID' exists, and bit 1 is used to indicate whether it is a broadcasting message or a P2P message. , The top six bits (bits 2 through 7) currently have no specific purpose and are reserved.

The 'Parameters' field contains a 'Command Code' item of 1 byte, a 'Window size' item of 2 bytes, and a Preservation Status item of 1 byte.The value of the 'Command Code' item is '0x10' when it is a collection command. .

Meanwhile, referring to FIG. 4, the RFID ID system 40 according to the present invention includes an RFID reader 41 and an RFID tag 42 and complies with the ISO / IEC 18000-7 standard.

4 illustrates one RFID reader 41 and one RFID tag 42 for convenience of description, but the number of RFID readers 41 and the number of RFID tags responding to each RFID reader are not limited.

The RFID reader 41 and the RFID tag 42 may be configured to operate in various ways according to respective RFID applications, and in particular, the RFID reader 41 and the RFID tag 42 according to the present invention will be described below. Perform the collection process to reduce collisions.

Referring to FIG. 4, a process of operating the RFID reader 41 and the RFID tag 42 according to the present invention will be described.

First, the RFID reader 41 to perform the collection process sets a message to be broadcast to the RFID tag 42 as follows (S41).

In the 'Command Type' field, information indicating whether to distinguish a tag by an AFI (Application Family Identifier) and a memory address of an RFID tag in which an AFI value is stored are set. In the 'Parameters' field, an AFI value of a response target tag is set.

Referring to FIG. 5, for a specific example of where to set each piece of such information, information indicating that a tag is classified by AFI may be set in the most significant bit of the 'Command Type' field, and the AFI value is stored. The memory address of the RFID tag can be set in the fourth to seventh bits (hereinafter, referred to as an 'address' section) of the 'command type' field.

At this time, if the most significant bit (hereinafter, referred to as 'Mask Enable' bit) of the 'Command Type' field is '0', it means that the collection process is performed as in the prior art, and if it is '1', the tag is tagged with AFI according to the present invention. This means that only RFID tags with the specified AFI will participate in the collection process.

In addition, the AFI value of the response target tag may be set to the lowest 1 byte (hereinafter, referred to as a 'mask' byte) of the 'Parameters' field.

That is, the message format directed from the RFID reader 41 to the RFID tag 42 follows the ISO / IEC 18000-7 protocol, but using the 'Reserved section' existing in the 'Command Type' field and the collection command format. The invention can be constructed.

The meaning of each of the above information is summarized in Table 1 below.

Mask Enable bit 0: don't distinguish tags by AFI (use the old way) 1: tag separated by AFI Address section AFI address is indicated in PC area of tag memory 'bank01' (byte unit). Mask byte The AFI value you want to find (for example, international classification AFI value)

For example, setting the Mask Enable bit value to '1' indicates that the tag is classified as an AFI value, and the Address section and Mask byte have meaning.

At this time, the value of the address section can be set in byte unit '3', which indicates the position of '0x18' in the PC (Protocol Control) region of the memory bank 'bank01' of the RFID tag, as described below. This is because AFI information is entered in.

Referring to FIG. 6, the standard for the RFID tag memory is very similar to that of ISO / IEC and that of EPC Global.

FIG. 6A shows a tag memory structure of ISO / IEC 18000-6C, and FIG. 6B shows a tag memory structure of EPC Class1 Gen2, and four memory banks Bank00 to Bank11 are defined.

In the tag memory structure of ISO / IEC 18000-6C, each bank is defined for User, Tag Identifier (TID), Unique Item Identifier (UII), Reserved State, and the tag memory structure of EPC Class1 Gen2. Each bank is defined as a user, a tag identifier (TID), an electronic product code (EPC), and a reserved state.

In particular, tag applications are divided into AFIs that comply with ISO / IEC 15961 and ISO / IEC 15962 standards. In other words, AFI tells us what kind of tag it is for (mobile, logistics, transportation, aviation, distribution, etc.) and which code it is stored in. Such AFI exists in the protocol control (PC) area of the memory bank 'bank01' in both FIGS. 6A and 6B and has a size of 1 byte (8 bits).

Looking at the structure of the memory bank 'bank01' with reference to FIG. 7, two bytes of CRC-16 information, two bytes of PC information, and UII (or EPC) data are recorded from the lowest address. It is used to check the movement information error between the tag and the RFID reader.

Here, the 5-bit 'length' item of the 2-byte PC information indicates the word length '-1' value of '(PC + UII data)', and the 2-bit RFU (Reserved for Future Use) item is It is a section reserved for future use, and 1-bit 'Toggle (T)' item indicates EPC information when '0' and '1' indicates Non-EPC information. Then, there is an AFI item of 1 byte.

Therefore, the memory address (that is, the address where the AFI value is stored) of the RFID tag set in the Address section in step S41 becomes the address (0x18 to 0x1F) where the AFI value is stored in the memory bank 'bank01'. Since the start address of this address section is set, '0x18' is set, and '0x18' is '3' in byte units.

4, if the message format is set through step S41, the RFID reader 41 broadcasts the message (S42).

Since the message broadcast in step S42 is a collection command message, the 'Command Code' item in the 'Parameters' field is set to '0x10'.

Meanwhile, the RFID tag 42 receiving the collection command message transmitted by the RFID reader 41 checks whether or not it is indicated that the tag is classified as AFI in the 'Command Type' field of the received message (S43). .

That is, the process checks whether the Mask Enable bit is set to '0' or '1'.

As a result of checking in step S43, if the 'Command Type' field of the received message does not indicate that the tag is classified as AFI (i.e., the Mask Enable bit is set to '0'), all RFID tags as in the prior art Needs to respond to the collection command, it performs a procedure of allocating a time slot and responding (S44, S49).

However, as a result of the checking in step S43, if it is indicated in the 'Command Type' field of the received message that the tag is classified as AFI (that is, the Mask Enable bit is set to '1') (S44), the received message is received. Check the AFI storage address set in the 'Command Type' field of the message (S45). That is, in step S45, the value set in the address section is confirmed.

Then, the value (AFI value) stored in its memory corresponding to the address confirmed in step S45 is the value set in the AFI value (ie, Mask byte) of the response target tag included in the message received in step S42. Check whether it is the same as (S46).

If the result of the check in step S46 is the same, a response message is transmitted to the RFID reader 41 by participating in the collection process (S47). Otherwise, the response message is not transmitted without participating in the collection process (S48).

As such, according to the present invention, the RFID reader 41 may allow all RFID tags to participate in the collection round when the collection process is performed, or select specific RFID tags to participate in the collection round.

A detailed example will be described with reference to FIG. 8.

Currently, RFID tags # 1 and # 2 are located within the communication range of the RFID reader 41, '0xB2' is recorded in the AFI storage space of the memory 81 provided in the RFID tag # 1, and the RFID tag # 2 It is assumed that '0xC2' is recorded in the AFI storage space of the memory 82 provided at.

In order to perform the collection process, the RFID reader 41 sets a value ('1') indicating that the tag is classified as AFI in the Mask Enable bit, and an address (byte unit) in which the AFI value is stored in the tag memory in the address section. Is set to '3'), and the Mask byte broadcasts a collection command message that sets '0xB2' that it is looking for.

Then, the RFID tags # 1 and # 2 determine whether to participate in the collection process by referring to the AFI value stored in their memory, so that only RFID tag # 1 participates in the collection process and transmits a response message. RFID tag # 2 does not participate in the collection process.

Each embodiment described above is intended to help the understanding of the present invention, the present invention is not limited to the above embodiments and can be variously modified and implemented by those skilled in the art without departing from the technical spirit of the present invention. Of course.

1 is an overview of an RFID system,

2 is an example for explaining a conventional collection process,

3 is a message format directed to an RFID tag in a conventional RFID reader,

4 is an embodiment of a collection process performed by an RFID system according to the present invention;

5 is a message format directed from an RFID reader to an RFID tag according to the present invention;

6 illustrates an example of a tag memory structure;

7 is an example of a bank01 structure of a tag memory;

8 is an overview of the collection process in accordance with the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

11,41: RFID Reader 12,42: RFID Tag

40: RFID system 81,82: tag memory

Claims (5)

In the RFID ID system comprising an RFID reader and an RFID tag that communicate with each other using RF signals according to the ISO / IEC 18000-7 standard, When the RFID reader transmits a collection command to the RFID tag, information indicating that the tag is classified by an application family identifier (AFI) in a 'Command Type' field of a message format and a memory address where an AFI value is stored are stored. And set the AFI value of the response target tag in the 'Parameters' field to broadcast it. When the RFID tag indicates that the message received from the RFID reader is classified into the AFI, the data is set in the received message by accessing data of a memory address set in the received message. Is configured to respond to the collection command only when it is equal to an AFI value of the reply-to tag that is present, Information indicating that the tag is classified by the AFI is set in the most significant bit of the 'Command Type' field, and the memory address in which the AFI value is stored is located in the fourth to seventh bits of the 'Command Type' field. RF ID system, characterized in that set. delete The method of claim 1, And the memory address in which the AFI value is stored is configured to set the address '0x18' of 'bank01' in the bank of the RFID tag memory. The method of claim 1, And the AFI value of the response target tag is configured to be set to the least significant byte of the 'Parameters' field. The method of claim 1, And the RFID tag is configured to respond to the collection command when the message received from the RFID reader is not marked to classify the tag into the AFI.

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