CN100501758C - A communication method between reader and tag in RFID system - Google Patents

Abstract

A communicating method between reader and countermark in RFID system includes detecting whether there is countermark in operation region or not by reader, changing relevant flag bit of detected countermark according to command parameter of reader, querying selected countermark by reader, switching unique countermark in reader at one moment, carrying out right certification by reader and countermark with each other then carrying out write/read operation on countermark by reader.

Description

A communication method between reader and tag in RFID system

technical field

The invention relates to the technical field of radio frequency identification, in particular to a communication method between a reader and a tag in an RFID system.

Background technique

In item identification, the use of barcodes is very common because it has very low cost, but it is very limited, such as being affected by light, stains, occlusions, etc. 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.

An RFID system can consist of at least one reader and one electronic tag. The reader and the tag communicate wirelessly. The reader can send an interrogation signal to the tag and read relevant information from the tag. With the development of RFID technology, tags are constantly developing from read-only small storage to writable large storage. Tags can be divided into active tags and passive tags. Active tags have a power supply inside and can actively communicate with readers; passive tags have no power inside and are transmitted from electromagnetic waves sent by readers. It absorbs electric energy as the power source for its work, and sends relevant information to the reader in the way of back reflection, completing the communication from the tag to the reader.

At present, RFID technology is in the critical stage of the formation of international standards. There are two main international standards for UHF (Ultra-high frequency, hereinafter referred to as UHF) RFID air interface standards: EPCglobal GEN2 and ISO 18000-6 . EPCglobal GEN2 is the second-generation UHF air interface standard (GEN2 for short) formulated by the Electronic Product Code (EPC) Management Center (EPCglobal), a non-profit standardization organization. In GEN2, in the communication process between the reader and the tag, three processes are defined for the reader: Select (selection), Inventory (inventory), Access (access), and the corresponding tag status is Ready (ready), Arbitrate (Arbitration), Reply (response), Acknowledged (confirmation), Open (open), Secured (protection), Killed (killing), the entire communication process is completed between these operations and states. The design of GEN2 is centered around the reading of EPC codes, and it does not take enough consideration of other types of information carried by tags and their interaction. The three operation processes of the reader play a simple and easy-to-implement role, but relatively speaking, the functional mechanism is not strict enough. For example, the security mechanism has a verification process of 16-bit random or pseudo-random data (RN16), but from the mechanism There is no sufficient consideration in terms of technology, and there is no room for technological upgrades. The corresponding relationship between the operation process of the reader and the state of the tag is not clear enough. In GEN2, the energy saving problem for handheld terminals is not considered.

Contents of the invention

The present invention is aimed at these problems and proposes an efficient and safe communication method between a reader and multiple tags, so that the communication between the reader and the tags is more complete and powerful in terms of framework and mechanism, so that the tags The state transition of the system is more flexible, and the correspondence with the operation process of the reader is more clear, which is conducive to improving the performance of RFID in an all-round way.

In view of the above, the purpose of the present invention is to provide a communication method between a reader and a tag in an RFID system, in which a new framework and a new functional mechanism for communication between a reader and a tag are provided, which Including the following steps:

In the first step, when the tag enters the effective radio frequency activation area, or the reader enters the tag presence area, the reader sends out a detection signal and performs a detection operation to detect whether there is a tag in the area:

When the tag exists, the tag is powered on, sends a response signal at the same time, and enters the ready state, and executes the second step;

If there is no response, it is considered that there is no tag, and the reader will not perform other operations;

In the second step, the above-mentioned detected response tag changes the corresponding flag according to the parameters of the selection operation instruction sent by the reader, and the selected tag is transferred to the selection state;

In the third step, the reader performs query operations on the above selected tags;

In the fourth step, the above-mentioned selected tags respond to the query operation command of the reader. When multiple selected tags respond on the same channel at the same time, the above-mentioned tags enter the arbitration state, and use the arbitration method to place the unique tag in a Connect to the reader at all times, and the reader performs the access operation at this time;

The fifth step, when a unique tag is successfully accessed, the reader performs an authentication operation on the tag. After the authentication is passed, it sends an instruction with a key to the tag to request tag authentication. At this time, the tag is in the authentication state , after the tag receives the instruction from the reader requesting authentication, it will authenticate it, and the tag will turn into an open state after passing; when the authentication between the reader and the tag is not required, this step is omitted, and the fourth step directly enters the second step. six steps;

The sixth step, when the tag connected to the reader enters the open state, the reader operates on the tag, including the read sub-operation, write sub-operation and "kill" sub-operation; the reader can choose the operation mode of the tag:

If the reader selects the read operation, it first sends an instruction, and after the tag verifies the instruction, it enters the read state, and then the reader performs a read operation on the tag; here, the read operation can be multiple different read operations, through the different permissions in the read instruction Key difference, after the tag verifies the command, send the information required by the reader to the reader;

If the reader selects the write operation, it first sends the command, and after the tag verifies the command, it enters the write state, and then the reader performs the write operation on the tag. Here, the write operation can be multiple different write operations, through different permissions in the write command key difference;

When the reader chooses to "kill" the tag, the reader sends an instruction with a key, and after the tag verifies the instruction, it enters the killing state.

Further, when the reader performs an inquiry operation on the selected tag in the above third step, it initializes the selected tag through an instruction, and initiates an inventory. The inventory refers to the entire process from selecting the tag to the end of the operation on the tag.

Further, in the fifth step above, when the authentication is successful, the reader first reads the unique identification code of the tag as an identification.

Further, in the sixth step above, when the tag is in the open state, according to different operation instructions of the reader, select to enter the read state, write state or kill state of the tag, except for the case of power failure, the tag in the read state and write state Can return to the open state or go directly to the kill state through the reader command.

Furthermore, in the sixth step above, when the tag is transferred between the open state, the read state, the write state and the killed state, it needs to pass the key authentication of different authority levels in the reader command.

Furthermore, the tag cannot transfer to any other state in the killed state.

Furthermore, if the tag is in any state, it must restart from the ready state when it is powered off.

Further, when errors occur in the arbitration, authentication and open states, the tags automatically enter the ready state; when errors occur in the read, write, and kill states, the tags automatically enter the open states.

The specific implementation of the present invention will be further described in detail below in conjunction with the accompanying drawings. The above and other objects, features and advantages of the present invention will be apparent to those skilled in the art from the detailed description of the method of the present invention.

Description of drawings

Fig. 1 is a diagram of the operation process of the reader in the present invention.

Fig. 2 State transition diagram of tags in the present invention.

Fig. 3 is the communication process diagram between the reader and the tag in the present invention.

Detailed ways

The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the (logic) operation and definition thereof of the reader involved in the present invention are described as follows:

S0: Detection (ie Detection)

When the reader enters a working area, the reader sends out a detection command to detect whether there is a tag in the area.

S1: Selection (ie Selection)

The reader selects and classifies the tags in the effective area through certain instructions. Here, it is allowed to use multiple selection commands to select tags multiple times until the predetermined selection task is completed.

S2: Query (ie Query)

The reader queries the selected tags, where the reader initializes the selected tags through instructions and initiates an inventory. The inventory here refers to the whole process from being selected to the end of the label operation.

S3: Access (ie Access)

If there are multiple tags responding on the same channel, a collision will occur. At this time, a certain arbitration method will be adopted to prevent the conflict, so as to ensure that the only tag is successfully connected at one time.

S4: Authentication (ie Authentication)

After the reader and the tag mutually authenticate as legal identities through a certain authentication mechanism, a secure communication link is established between the reader and the tag.

S5: Operation (ie Operation)

The operation of the reader on the tag includes S5R: read (Read) sub-operation, and S5W: write (Write) sub-operation and S5D: "kill" sub-operation.

As shown in Figure 2, the label states and their definitions involved in the present invention are described as follows:

S6: Ready (ie Ready)

The ready state can be seen as a waiting state, which is used to represent the state of a tag that has not yet accepted any read or write operations from the reader, nor has it entered an inventory process. After a tag enters the radio frequency activation area, except for the killing state, it will enter this state when it is powered off. The tag remains in this state until it receives a selection command from the reader.

S7: Selection (ie Selection)

Before the reader counts the tags, it will select the tags according to the requirements. When the reader sends out the selection command, the corresponding tag will automatically enter the selection state, and at the same time generate the corresponding selection mark, that is, change the corresponding flag bit. The tag in the state will enter the arbitration state and respond to subsequent query commands.

S8: Arbitration (ie Arbitration)

The Arbitration state is a hold state for those Tags that are the only ones connected to the reader that are participating in the current inventory process but have not yet obtained an available channel. The tag in this state can receive various instructions sent by the reader to achieve arbitration, and it will not leave this state until it is successfully connected, and enter the authentication state.

S9: Authentication (ie Authentication)

When the tag is successfully connected, except for the power-off or Dead state, the tag enters the authentication state. In this state, the tag responds to various authentication instructions sent by the reader to ensure that the identities of both parties are legal, and only then can a secure communication link be established, making subsequent information interactions safe.

S10: open (that is, Open)

When the mutual authentication between the tag and the reader succeeds, the tag enters the open state. In this state, the tag chooses to enter the read, write or kill state according to different instructions from the reader. In addition to the power-off or kill state, tags in the read and write states can be returned to the open state by a reader command.

S11: Read (ie Read)

When the tag enters the open state, it can enter this state according to the instruction of the reader. In this state, the reader has the right to read the relevant information of the tag. For information in different areas, different instructions are required, and these instructions contain keys with different read permissions. In this state, it can be transferred to write or kill state, or return to open state according to different instructions of the reader.

S12: Write (ie Write)

When the tag enters the open state, it can enter this state according to the reader's instruction. In this state, the reader has the right to write to the tag. For write operations in different areas, different instructions are required, and these instructions contain keys with different write permissions to complete different write operations. In this state, the tag can turn into the read and kill) state, or return to the open state according to different instructions.

S13: Kill (i.e. Dead)

When the tag enters the open state, it can enter this state according to the reader's instruction. In this state, the tag no longer responds to any other instructions from the reader, which can be called a killed state. In this state, the tag cannot transfer to any other state.

As shown in Figure 3, the specific process of the communication method between the reader and the tag provided by the present invention includes the following steps:

The first step: the reader detects the working area and detects whether there is a label

When the tag enters the effective radio frequency activation area, or the reader enters the tag presence area, the reader performs the SO: Detection operation as shown in Figure 1: first, the reader sends out a detection signal, such as a specific continuous carrier, the tag The signal is demodulated, and a specific response signal is emitted back to ensure that the reader can identify the existence of the tag, that is, S14 to S15 in Figure 3. When the tag exists, the tag is powered on, sends a response signal at the same time, and enters the S6 in Figure 2: Ready (Ready) state, that is, S15 to S16 in Figure 3 .

Step 2: The reader selects the detected pre-communication tags

When it is detected that there is a label, the label is selected, that is, S16 to S17 in FIG. 3 . At this time, the reader performs S1 in FIG. 1: selection (Selection) operation. The tag changes the corresponding flag bit according to the parameters of the selection command, and turns to S7 in Figure 2: Selection (Selection) state. More specifically, here the reader can select and classify the tags in the effective area through one or more selection instructions. This directive can include specific information in the directive, via parameter selection tags. This instruction can contain a specific sequence, and specify to perform logical operations with a specific part of the information stored in the tag, and use the result to change the part of the tag to achieve the purpose of selection. For example, an information sequence 101010 is included in the instruction, and it is used to select a certain segment of storage information of a label and the same label. In a specific application, for example, in a warehouse, select all a certain type of food produced by a specified manufacturer, then the reader will match it in the instruction according to the coding characteristics corresponding to these characteristics, and then identify this type of food. items for subsequent operations.

Step 3: The reader queries the selected tag

The reader performs S2 in FIG. 1: query (Query) operation on the selected tag, that is, S18 to S19 in FIG. 3 . And initialize the selected label through certain instructions, and start counting the labels.

The fourth step is to connect the tag to the reader

The selected tag responds to the reader's query command. When multiple tags respond on the same channel at the same time, a conflict will occur. Here, a certain arbitration method can be used, such as the ALOHA algorithm to avoid conflicts. At this time, the tag is in the S8: Arbitration state in FIG. 2 . After the arbitration, at this time the reader performs the S3 access (Access) operation in Figure 1, and accesses the unique tag to the reader at one time, that is, S19 to S20 in Figure 3 .

Step 5 Mutual authentication between the reader and the tag

When a unique tag is successfully accessed, the reader authenticates the tag, and after passing the authentication, sends an instruction with a key to the tag to request tag authentication, namely S20 to S21 in Figure 3. At this time, the operation of the reader is S4: Authentication (Authentication) in FIG. 1 , and the tag is in S9: Authentication (Authentication) state in FIG. 2 . After the tag receives the instruction requesting authentication, it authenticates it, and then transfers to S10: Open state, that is, S21 to S22 in Fig. 3 . After mutual identification of legal identities through authentication, the reader first reads the legal unique identification code of the tag, such as the unique identifier (UID code for short). More specifically, for example, the tag can first send a command with a key, which includes a random number at the same time. When the reader receives the command, it verifies the key, and returns the received random number after the verification is passed. . When the two parties authenticate each other as legal identities through a certain authentication mechanism, a secure communication link is established between the reader and the tag.

The sixth step is that the reader reads and writes the tag

When the tag enters the S10: Open (Open) state, the reader can choose the operation mode for the tag. If you choose S5R in Figure 1: Read (Read) operation, first send an instruction to make the tag transfer to S11 in Figure 2: Read (Read) state, and then the reader performs a read operation on the tag, here the read operation can be multiple Different read operations are distinguished by keys with different permissions in the read command, that is, S22 to S23 in FIG. 3 . After the tag verifies the instruction, send the information required by the reader to the reader, that is, S23 to S24 in FIG. 3 , for example, EPC information of the tag, user information, etc. If the reader selects the S5W in Figure 1: Write (Write) operation, first send an instruction to make the tag transfer to the S12: Write (Write) state in Figure 2, and then the reader performs a write operation on the tag, where the write operation can be Multiple different write operations are distinguished by keys with different permissions in the write command, that is, S24 to S25 in Figure 3. For example, EPC information, user information, etc. can be rewritten through different commands or parameters. For rewriting some important information, you need The key is included in the command. When the reader selects the S5D in Figure 1: "Dead" operation, the reader sends an instruction with a key, the tag verifies the instruction, and transfers to S13 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 commands.

In addition, in the open (Open) state, the tag can choose to enter any one of the read (Read), write (Write) and kill (Dead) states according to the reader's instructions. , can switch states according to the instruction of the reader, or turn into the dead state, or return to the open state. After entering the Dead state, the tag will not transfer to other states. In a specific application, not all tags must be read, or written, or read and write at the same time, so a choice can be made. For example, in the item management process of a supermarket or a warehouse, the item is identified by the unique identification code (Identification, hereinafter referred to as ID) of the tag attached to it. The ID of this tag is predetermined and unique. The management process of items is based on ID management. In this way, in the RFID-based management system, the background database will monitor the existing items in real time. For example, when the item is a new item, it must be read. Get its item information, such as name, material, size, shelf life, storage environment and so on. When the item is stored for a long time, for example, its price needs to be adjusted, then after communication with the tag is established, the write operation can be directly performed to rewrite the price information storage area. When the storage time of the item is longer than the shelf life, the "kill" operation is directly performed on it without entering into other states of the operation. Because these monitoring are done in advance in the background database.

In the present invention, the fifth step may not be used during system design, that is, it is allowed to directly enter the sixth step from the fourth step. For example, on the production line of a factory, there is no safety hazard for product identification, so it can be omitted to improve efficiency. But if it is used in the access control system, the communication security of the system should be paid attention to, and the fifth step should be reserved.

In the present invention, the state shown in FIG. 2 is a logical state of the tag, and each logical state may correspond to multiple physical states. For example, in the Arbitration state, multiple physical response states will be generated according to responses to different commands. For example, in the Write state, there will be different physical states according to different contents written. If the tag is in any state, it must restart from the Ready state when it is powered off. When an error occurs in the Arbitration, Authentication and Open states, the tag automatically turns to the Ready state. When the tag has an error in the read (Read), write (Write) and kill (Dead) states, it will automatically turn to the open (Open) state.

The embodiments of the present invention have been described in detail above, but these are only vivid examples for easy understanding, and should not be regarded as limiting the scope of the present invention. Similarly, any ordinary professional in the technical field can make various possible equivalent changes or replacements according to the technical solution of the present invention and the description of its preferred embodiments, but all these changes or replacements should belong to the scope of the present invention. The scope of the claims.

Claims (7)

1, the communication means of reader and label in a kind of rfid system, it comprises the steps:

The first step, when label enters effective radio frequency active region, after perhaps reader entered label and has the district, reader sent detection signal, carries out detecting operation, so that whether label is arranged in the surveyed area exists:

When label existed, label powered on, and sent response signal simultaneously, and entered ready state, carried out for second step;

Do not have label to exist if response is just thought, reader no longer carries out other operation;

Second step, the corresponding zone bit of parameter change that the selection operation that above-mentioned detected responding tags is sent according to reader instructs, selected label changes selection mode over to;

In the 3rd step, reader carries out query manipulation to above-mentioned selected label;

The 4th step, instruction responds above-mentioned selected label to the query manipulation of reader, and during simultaneously at same channel response, above-mentioned these labels enter arbitrate state as a plurality of labels, utilize referee method that unique tags is inserted reader a moment, this moment, reader carried out access operation;

The 5th step, after unique tags inserts successfully, reader carries out authentication operations to label, after authentication is passed through, send the instruction that has key, request label authentication to label, this moment, label was in authentication status, after label is received the instruction of reader requests authentication, it is carried out authentication, change open state over to by the back label; When not needing authentication between reader and the label, omit this step, directly went into for the 6th step, and label directly changes open state over to by the 4th stepping;

In the 6th step, after the label that inserts reader entered open state, reader was operated label, comprised to read child-operation and write child-operation, " killing " child-operation; Reader can be selected the mode of operation to label:

If reader is selected read operation, at first send instruction, label changes read states over to after instruction is verified, and reader carries out read operation to label afterwards; Here read operation can be a plurality of different read operations, by the key difference of different rights in reading instruction, after the label checking instruction, sends the information of reader demand to reader;

If reader is selected write operation, at first send instruction, label changes the state of writing over to after instruction is verified, and reader carries out write operation to label afterwards, and write operation can be a plurality of different write operations here, by the key difference of different rights in the write command;

When the reader selection was carried out " killing " operation to label, reader sent the instruction that has key, and label changes the state of killing over to after instruction is verified.

2, method according to claim 1, when it is characterized in that reader carries out query manipulation to selected label in above-mentioned the 3rd step, by instruction selected label is carried out initialization, and initiate to check, check and be meant from selecting label to whole process to the EO of label.

3, method according to claim 1 is characterized in that in above-mentioned the 5th step that reader is the unique identification sign indicating number of reading tag at first, as the identify label of label in authentication when success.

4, method according to claim 1, it is characterized in that label is under open state in above-mentioned the 6th step, different operating instruction according to reader, selection enter label read states, write state or kill state, remove the situation of outage, be in read states and can return open state or directly enter the state of killing by the reader instruction with the label of writing state.

5,, it is characterized in that label can not be again to other any state transitions under the state of killing according to claim 1 or 4 described methods.

6, method according to claim 1 is characterized in that label is under any one state, after outage, must restart from ready state.

7, method according to claim 1 is characterized in that changing ready state automatically over to when mistake appears in label under arbitration, authentication and open state; When label in reading and writing with kill under the state and to occur changing open state automatically over to when wrong.

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