WO2007147306A1

WO2007147306A1 - A communication method between reader and label in the rfid system

Info

Publication number: WO2007147306A1
Application number: PCT/CN2006/003740
Authority: WO
Inventors: Honggang Wang; Limin Zhou
Original assignee: Zte Corporation
Priority date: 2006-06-13
Filing date: 2006-12-30
Publication date: 2007-12-27
Also published as: CN101089872A; CN100501758C

Abstract

A communication method between the reader and the label in the RFID system is disclosed. The method includes the follow steps: the first step, the reader detects whether the label existing in the work area; the second step, the detected label changes the corresponding flag bit according to the parameter of the selection instruction of the reader; the third step, the reader queries the selected label; the forth step, the reader receives the single label at one moment according to the arbitrating method of the reader; the fifth step, the reader and the label authenticates each other; the sixth step, the reader reads/writes the label. The method of the present invention makes the change of the reader’s state more flexible and corresponds to the operation process of the reader more explicit, so that the communication between the reader and the label can be improved more perfectly, strongly, safely and high efficiency on the frame and mechanism, and be in favor of upgrading the performance of RFID.

Description

TECHNICAL FIELD The present invention relates to the field of radio frequency identification technologies, and in particular to a method for communicating a reader and a tag in an RFID system. BACKGROUND OF THE INVENTION In the identification of articles, the use of bar codes is very common because of its low cost, but it is limited, such as by light, stains, obstructions, and the like. The emergence of RFID technology completely overcomes these shortcomings. RFID can identify a single very specific object, and can also read multiple objects at the same time. The RFID system can be composed of at least one reader and an electronic tag. The reader and the tag communicate wirelessly. The reader can send an inquiry signal to the tag and read the relevant information from the tag. With the development of RFID technology, tags have evolved from a small amount of read-only storage to a large amount of writable storage. The tag can be divided into an active tag and a passive tag. The active tag has a power supply inside, and can actively communicate with the reader. The passive tag has no power inside, and the electromagnetic wave is sent from the reader. The power is drawn, as a power source for its operation, and the information is sent to the reader in a back-projection manner to complete the communication of the tag to the reader. At present, RFID technology is at the critical stage of the formation of international standards. Regarding the standards of Ultra-high frequency (UHF) RFID air interface, there are two main international standards: EPCglobal GEN2 and ISO 18000- 6. EPCglobal GEN2 is the second generation UHF air interface standard (GEN2) developed by the non-profit standardization organization, Electronic Product Code (EPC) Management Center (EPCglobal). In GEN2, during the communication between the reader and the tag, three processes are defined for the reader: Select, Inventory, Access, the corresponding tag status is Ready, Arbitrate (Arbitration), Reply, Acknowledged Open, Secured, Killed, the entire communication process is completed between these operations and states. The design of GEN2 is around the reading of EPC codes, and the tags carry other types of information and their interactions are not enough. The three operating procedures of the reader play a role in the easy implementation of the cartridge, but relatively speaking, the functional mechanism is not strict enough, for example, the security mechanism, there is a 16-bit random or pseudo-random data (RN16) verification process, However, there is no adequate consideration from the mechanism, and there is no room for technological upgrading. The correspondence between the operation of the reader and the state of the tag is not clear enough. Energy saving issues for handheld terminals are not considered in GEN2. SUMMARY OF THE INVENTION The present invention is directed to these problems to provide an efficient and secure communication method between a reader and a plurality of tags, which makes the communication between the reader and the tag more complete and powerful in terms of framework and mechanism. It makes the state transition of the tag more flexible and more clear with the operation process of the reader, which is beneficial to the overall improvement of the performance of the RFID. In view of the above, it is an object of the present invention to provide a communication method between a reader and a tag in an RFID system, in which a new framework for communication between a reader and a tag and a new functional mechanism are provided. The following steps are performed on the packet: In the first step, when the tag enters the active RF activation zone, or the reader enters the tag presence zone, the reader sends a detection signal to perform a detection operation to detect whether a tag exists in the area: When the tag exists When the tag is powered on, the response signal is sent, and the ready state is entered, and the second step is performed; if there is no response, no tag is considered to exist, and the reader does not perform other operations; in the second step, the label of the detected response is based on The parameter of the selection operation instruction sent by the reader changes the corresponding flag bit, and the selected label enters the selection state; the third step, the reader performs a query operation on the selected label; and the fourth step, the query operation of the selected label on the reader The command responds, when the tags with multiple selected states are simultaneously responding on the same channel, the above tags In the arbitration state, using the arbitration method, the unique tag is connected to the reader at one moment, and the reader performs the access operation; the fifth step, after the unique tag is successfully accessed, the reader authenticates the tag. After the authentication is passed, the instruction with the key is sent to the tag, and the tag is claimed. At this time, the tag is in the authentication state, and after the tag receives the instruction for the reader to request authentication, it is authenticated, and after passing the authentication, The label is transferred to the open state; when no authentication is required between the reader and the label, the step is omitted, and the fourth step is directly entered into the sixth step; In the sixth step, after the tag of the access reader enters the open state, the reader operates the tag, including the read sub-operation, the write sub-operation, and the "kill"sub-operation; the reader can select the operation mode of the tag: The reader selects the read operation, first sends the instruction, and after the label verifies the instruction, it transfers to the read state, and then the reader reads the label; here the read operation can be a plurality of different read operations, by reading the secret of different permissions in the instruction Key difference, after the label verification instruction, send the reader the information required by the reader; if the reader selects the write operation, first sends the instruction, the label verifies the instruction, and then enters the write state, after which the reader writes the label, Here, the write operation can be a plurality of different write operations, which are distinguished by the keys of different permissions in the write command; when the reader chooses to "kill" the tag, the reader sends the command with the key, the tag pair instruction After entering the face of the face i, turn into the kill state. Further, in the third step, when the reader performs a query operation on the selected tag, the selected tag is initialized by an instruction, and an inventory is initiated, and the inventory refers to the entire process of selecting the tag to end the operation of the tag. Further, in the fifth step, when the authentication succeeds, the reader first reads the unique identification code of the tag as the identity identifier. Further, in the sixth step, the label is in an open state, and according to different operation instructions of the reader, the label enters the read state, the write state, or the kill state, and in addition to the power-off condition, the label in the read state and the write state. It can be returned to the open state by the reader command or directly to the kill state. Further, when the label is moved between the open state, the read state, the write state, and the kill state in the sixth step, the key authentication of different privilege levels in the reader command is required. Further, the tag cannot be transferred to any other state in the killed state. Further, the tag is in any state, and after the power is turned off, it must be restarted from the ready state. Further, when the tag has an error in arbitration, authentication, and open state, it automatically enters the ready state; when the tag has an error in the read, write, and kill states, it automatically transitions to the open state. The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings. The above and other objects, features and advantages of the present invention will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process chart of a reader in the present invention. Figure 2 is a state transition diagram of the label in the present invention. Figure 3 is a diagram showing the communication process of the reader and the tag in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. As shown in FIG. 1, the (logical) operation of the reader and its definitions of the present invention are as follows:

SO: Detection (ie Detection) When the reader enters a work area, the reader issues a test command to detect if a tag exists in the area.

S1: Select (ie Selection) The reader selects and categorizes the labels in the active area with certain instructions. This allows multiple selections of the label to be used to select the label multiple times until the predetermined selection task is completed.

S2: Query (ie Query) The reader queries the selected tag, where the reader initializes the selected tag by an instruction and initiates an inventory. The enumeration here refers to the end of the operation from being selected to the tag. The whole process. S3: Access (ie Access) If there are multiple tags responding on the same channel, a collision will occur, and a certain arbitration method will be adopted to prevent collisions, so as to ensure that the unique tag is successfully accessed at one time.

S4: Authentication (? p Authentication ) After both the reader and the tag authenticate each other to a legal identity through a certain authentication mechanism, a secure communication link is established between the reader and the tag.

S5: Operation (ie Operation) The reader's operation on the tag includes the S5R: Read sub-operation, and the S5W: Write sub-operation and the S5D: "kill" sub-operation. As shown in FIG. 2, the label status and its definitions related to the present invention are as follows:

S6: Ready (Ready) The Ready state can be thought of as a wait state to indicate the status of a power-up tag that has not yet received any read or write operations from the reader and has not yet entered an inventory process. After a tag enters the RF active zone, it is switched to this state except for the kill state and power down. The tag will remain in this state until it receives a selection command from the reader.

S7: Selection (ie Selection) Before the reader enters the label, the label will be selected according to the requirements. When the reader issues a selection instruction, the response label is automatically transferred to the selection state, and the corresponding selection identifier is generated. The corresponding flag is changed. Only the tag entering the state enters the arbitration state and responds to subsequent query commands.

S8: Arbitration (Arbitration) The arbitration state is a hold state that indicates the tags that are participating in the current inventory process but have not yet obtained an available channel and are uniquely connected to the reader. The tag in this state can receive various commands sent by the reader for arbitration, and will not leave the state until the access is successful, and enter the authentication state.

S9: Authentication (ie, Authentication) When the tag is successfully accessed, the tag enters the authentication state except for the power-down or dead state. In this state, the tag responds to various commands for authentication sent by the reader to ensure that the identity of both parties is legal, so that a secure communication link can be established, so that subsequent information interaction is secure.

S 10: Open (ie Open) When the tag and the reader authenticate each other successfully, the tag enters an open state. In this state, the tag chooses to enter the read, write or kill state depending on the different instructions of the reader. In addition to powering down or killing the state, the tags in the read and write states can be returned to the open state by the reader command.

S11: Read (ie Read) When the tag enters the open state, it can enter this state according to the instructions of the reader. In this state, the reader has the right to read the relevant information of the tag. For different zones or information, different instructions are required, and these commands have keys with different read permissions. In this state, you can go to the write or kill state according to the different instructions of the reader, or return to the open state.

S12: Write (ie Write) When the tag enters the open state, it can enter this state according to the reader command. In this state, the reader has the right to write to the tag. For writes to different areas, different instructions are required, with keys with different write permissions in these instructions to perform different write operations. In this state, the tag can be read and killed according to different instructions, or returned to the open state.

S13: Kill (ie Dead) When the tag enters the open state, it can enter this state according to the reader command. In this state, the tag no longer responds to any other instructions of the reader and can be referred to as a kill state. In this state, the tag can no longer be transferred to any other state. As shown in FIG. 3, the specific process of the communication method between the reader and the label provided by the present invention includes the following steps: First, the reader detects the working area, and detects whether a label exists. When the label enters a valid radio frequency activation area, Or after the reader enters the tag presence area, the reader performs the SO: Detection operation as shown in Figure 1: First, the reader sends a detection signal, such as a specific continuous carrier, and the tag demodulates its signal and backs A specific response signal is emitted to ensure that the reader can discriminate the presence of the tag, namely S14 to S15 in FIG. When the tag is present, the tag is powered up, and a response is issued at the same time, and enters the S6: Ready state as shown in Figure 2, which is S 15 to S16 in Figure 3. The second step reader selects the detected pre-communication label When a tag is detected, the tag is selected, that is, S16 to S17 in Fig. 3. At this point, the reader performs the S1: Selection operation in Figure 1. The tag changes the corresponding flag bit according to the parameters of the selection instruction, and proceeds to S7 in the FIG. 2: Selection state. More specifically, the reader can select and classify tags within the active area by one or more selection commands. This command can contain specific information in the instruction and select the label by parameter. This instruction can contain a specific sequence and specify a logical operation with a specific part of the information stored in the tag, and use this result to change the part of the tag to achieve the purpose of selection. For example, the instruction sequence includes the information sequence 101010, and is used to select a certain piece of stored information of the tag and the same tag. In a specific application, for example, in a warehouse, selecting all kinds of foods produced by a certain manufacturer, the reader will match the instructions according to the coding characteristics corresponding to the features, and then identify the such products. Items for subsequent operations. The third step reader performs a query on the selected tag. The reader performs the S2: Query operation in FIG. 1 on the selected tag, that is, S18 to S19 in FIG. The selected tag is initialized with a certain instruction, and the tag is started to be counted. The fourth step of the tag access reader selects the tag to respond to the reader's query command. When multiple tags are simultaneously responding on the same channel, a conflict will occur. Here, a certain arbitration method can be used, such as using ALOHA. Algorithm to avoid conflicts. At this point the tag is in the S8: Arbitration state in Figure 2. After arbitration, the reader performs the S3 access operation in FIG. 1 to access the unique tag at one time, that is, S19 to S20 in FIG. Step 5: Reader and tag mutual authentication When a unique tag is successfully accessed, the reader authenticates the tag. After the authentication is passed, the command with the key is sent to the tag, requesting tag authentication, that is, Figure 3 In S20 to S21. At this point, the reader operates as S4 in Figure 1: Authentication, and the tag is in the S9: Authentication state in Figure 2. After receiving the instruction for requesting authentication, the tag authenticates it, and then passes to S10: Open state, that is, S21 to S22 in FIG. After the mutual identification of the legal identity by the authentication, the reader first reads the unique identification code of the tag, such as a unique identifier (Unique identifier, UID code). More specifically, for example, the tag may first send a command with a key, and include a random number in the instruction. When the reader receives the instruction, the key is verified, and after the verification is passed, the received random number is returned. . When both parties authenticate each other through a certain authentication mechanism, they are legal. After identity, a secure communication link is established between the reader and the tag. Step 6: The reader reads and writes the label. When the label enters the S10: Open state, the reader can choose how to operate the label. If you select the S5R: Read operation in Figure 1, the instruction is sent first, and the label is transferred to the S11: Read state in Figure 2. After the reader reads the label, the read operation can be multiple. Different read operations are distinguished by the keys of different permissions in the read command, that is, S22 to S23 in FIG. After the tag verification command, the reader is sent the information of the reader request, that is, S23 to S24 in FIG. 3, for example, the EPC information of the tag, the user information, and the like. If the reader selects the S5W: Write operation in Figure 1, the instruction is first sent, causing the label to go to the S12: Write state in Figure 2, after which the reader writes the label, where the write operation can be A plurality of different write operations are distinguished by a key of different permissions in the write command, that is, S24 to S25 in FIG. 3, for example, EPC information, user information, etc. can be rewritten by different instructions or parameters, and for rewriting of some important information, The command has a key. When the reader selects the S5D: "Dead" operation in Figure 1, the reader sends an instruction with a key, the tag verifies the instruction, and proceeds to S13 as shown in Figure 2: Kill (Dead) State, this process is S26 to S27 in Fig. 3. This action will cause the tag to no longer respond to any instructions. In addition, in the Open state, the tag can be selected to enter any of the Read, Write, and Dead states according to the reader command, in the Read (Read), Write (Write) state. , can convert state according to reader instructions, or go to the Dead state, or return to the Open state. When entering the Dead state, the tag no longer transitions to another state. In a particular application, not all tags must be read, written, or read and written simultaneously, so they can be selected. For example, in the item management process of a supermarket or warehouse, an item is identified by a unique identification (ID) of the label attached thereto, and the ID of the label is predetermined and unique. The management process of the item is based on the management of the ID. In the RFID-based management system, the database in the background monitors the existing items in real time. For example, when the item is a new item, it must be read. Take information about its items, such as name, material, size, shelf life, storage environment, and more. When the item is stored for a long period of time, for example, to adjust its price, then when communication is established with the tag, the write operation can be directly performed to rewrite the price information storage area. When the item is stored for longer than the shelf life, it is directly "killed" without having to go into other states of operation. Because these monitoring is in the background database in advance. In the present invention, the fifth step can be omitted during system design, that is, it can be directly from the fourth step. Go to the sixth step. For example, in the production line of a factory, there is no safety hazard in the identification of the product, so it can be omitted to improve efficiency. However, if it is used in the access control system, it is necessary to pay attention to the communication security of its system, and keep the fifth step. In the present invention, the state shown in FIG. 2 is a logical state of a tag, and each logical state may correspond to a plurality of physical states. For example, in the Arbitration state, responding to different instructions will generate multiple physical response states. Compared with ^, in the Write state, there will be different physical states depending on the different contents written. The tag is in any state, and after power down, it must be restarted from the Ready state. When the tag has an error in the Arbitration Authentication and Open state, it automatically goes to the Ready state. When the tag has an error in the Read, Write, and Dead states, it automatically goes into the Open state. The embodiments of the present invention have been described in detail above, but are merely illustrative examples of the present invention and are not intended to limit the scope of the invention. Also, any person skilled in the art can make various possible equivalent changes or substitutions according to the technical solutions of the present invention and the description of the preferred embodiments thereof, but all such changes or substitutions should belong to the present invention. The scope of protection of the claims.

Claims

The method for communicating a reader and a tag in an RFID system includes the following steps:

In the first step, when the tag enters the active RF activation area, or the reader enters the tag presence area, the reader sends a detection signal to perform a detection operation to detect whether a tag exists in the area:

When the tag exists, the tag is powered on, and a response signal is sent, and the ready state is entered, and the second step is performed. If there is no response, no tag is considered to exist, and the reader does not perform other operations. In the second step, the above detection is performed. The response tag changes the corresponding flag bit according to the parameter of the selection operation instruction issued by the reader, and the selected tag is transferred to the selection state;

In the third step, the reader performs a query operation on the selected label;

In the fourth step, the selected tag responds to the query operation command of the reader. When multiple tags are simultaneously responding on the same channel, the tags enter the arbitration state, and the unique tag is used to access the reader at one time by using the arbitration method. At this time, the reader performs an access operation. In the fifth step, after the unique tag is successfully accessed, the reader performs an authentication operation on the tag, and after the authentication is passed, sends a command with a key to the tag, requesting the tag. Right, at this time, the tag is in the authentication state. After the tag receives the instruction requesting authentication from the reader, it authenticates it, and then passes the tag to the open state. When the reader does not need authentication, the device is omitted. In this step, the fourth step is directly entered into the sixth step, and the label is directly transferred to the open state;

In the sixth step, after the tag of the access reader enters the open state, the reader operates the tag, including the read sub-operation and the write sub-operation, and the "kill" sub-operation; the reader can select the operation mode of the tag:

If the reader selects a read operation, the instruction is first sent, and after the tag verifies the instruction, it is transferred to the read state, and then the reader reads the tag; here, the read operation may be a plurality of different read operations, by reading the different permissions in the instruction. The key difference, after the label is issued, sends the reader the information required by the reader;

If the reader selects a write operation, the instruction is sent first, and after the label verifies the instruction, it is transferred to the write state, and then the reader writes the label, where the write operation may be multiple The same write operation, by writing the key difference between the different permissions in the command; when the reader chooses to "kill" the tag, the reader sends an instruction with the key, after the tag verifies the instruction, Into the kill state.

2. The method according to claim 1, wherein in the third step, when the reader performs a query operation on the selected tag, the selected tag is initialized by an instruction, and an inventory is initiated, and the inventory point is from the selection tag to The entire process of the end of the operation of the label.

3. The method according to claim 1, wherein in the fifth step, when the authentication is successful, the reader first reads the unique identification code of the tag as the identity of the tag.

4. The method according to claim 1, wherein in the sixth step, the tag is in an open state, and according to different operation instructions of the reader, selecting to enter a read state, a write state or a kill state of the tag, except for powering off. In the case of a read state and a write state, the tag can be returned to the open state by the reader command or directly to the kill state.

5. The method according to claim 1 or 4, wherein in the sixth step, when the label is transferred between an open state, a read state, a write state, and a kill state, different commands are required in the reader command. Level key authentication.

6. A method according to claim 1 or 4, characterized in that the tag cannot be transferred to any other state in the killed state.

7. The method of claim 1 wherein the tag is in any of the states and must be restarted from the ready state when the power is turned off.

8. The method according to claim 1, wherein when the tag has an error in arbitration, authentication, and open state, it automatically enters a ready state; when an error occurs in the read, write, and kill states of the tag, Moved to an open state.