KR100927879B1 - Effective RDF Collision Avoidance Control in Homogeneous Tag Recognition Environment - Google Patents

Abstract

The present invention relates to an efficient RFID collision avoidance control method in a homogeneous tag recognition environment. More particularly, when a collision occurs between tags in a reader recognition process, tag information is re-recognized and a lot of load generated on a network can be efficiently detected. The present invention relates to an efficient RFID collision avoidance control method in a homogeneous tag recognition environment.

Therefore, the present invention is effective in identifying homogeneous tags and can reduce the time required by up to 50% compared to identifying heterogeneous tags.

RFID, Collision Avoidance, Tag, Reader, Query, Queue

Description

Effective RDF Collision Avoidance Control in Homogeneous Tag Recognition Environment {Effective Methods for RFID Collection}

The present invention relates to an efficient RFID collision avoidance control method in a homogeneous tag recognition environment. More particularly, when a collision occurs between tags in a reader recognition process, tag information is re-recognized and a lot of load generated on a network can be efficiently detected. The present invention relates to an efficient RFID collision avoidance control method in a homogeneous tag recognition environment.

In the prior art, there are ALOHA based protocols and TREE based protocols to prevent collisions between transmission information that may occur during transmission.

In more detail, the ALOHA-based protocol is also called a probabilistic method, and a tag starvation phenomenon in which a particular tag is not identified to the reader for a long time in a way that reduces the probability of tag collision by transmitting an ID by selecting each tag at random time. Due to a collision between a tag starvation problem and partial information bits, there is a problem in that it takes a long time to identify a tag. Probability-based tag collision prevention methods include slotted ALOHA, frame slotted ALOHA, and adaptive frame slotted ALOHA. However, there is a problem that does not completely solve the collision problem.

In addition, the TREE-based protocol is also called a deterministic method, and the tree-based protocol includes a binary tree method and a query tree, and the binary tree method and the query tree method simultaneously identify IDs. If a tag collision occurs by grouping tags that transmit a tag into a set and identifying tags by a set unit, divide the set into two subsets and divide the tag set until one set contains only one tag. All tags existing within the range can be identified, but there is a problem that it takes a long time to identify the tags.

The binary tree technique and the query tree technique are described. The binary tree technique has a counter for distinguishing the random number generator from the group in the tag. When the message is initially transmitted from the reader, the tag is 0 and 1 as the random number generator. Generates one random number Add this random number to the counter to set the counter value. This process is repeated, and the tag is divided into a counter 0 group and a 1 group. The counter 0 group sends a message and the reader informs the tag whether it is identified. If a collision occurs during transmission, the transmission tags generate a random number and are divided into two groups again. If the tag has not been transmitted in the previous step, the counter is incremented by one. If there is no collision during transmission, all the tag counters are decreased by one. At this time, the tag which has been successfully identified has a negative counter value and is completed. This method generates a random number in a tag and can generate several dormant slots in the process of dividing the tag group into two.

1 is a flowchart of a conventional query tree scheme, and includes the following steps.

The reader taking a k-bit length query from the queue stored in the query and broadcasting the tag to the tag (S1); The tag compares a transmission query from a reader with its tag ID in bit order (S2); Transmitting the own tag ID to the reader when the comparison result matches its own tag ID and all bits of the received query (S3); After the query, the reader performs one of three states, i.e., idle state, succession state, and collision state according to the response of the tag (S4), and all tag bodies. Until the identification is made, step S5 is fed back to step S1.

In particular, when the step S4 is described in more detail in each of the above steps, the query retrieves another query from the queue where the query is in the dormant state and queries the tag again. Repeat the above steps (steps S1 to S4), and if there is a conflict, the reader adds 0 and 1 to the query previously sent to the tag, creates a new query, queues it, and performs the identification process again. .

In this case, if any collision between messages received from tags is transmitted, the number of transmission is increased by broadcasting the entire tag. Therefore, the tag identification speed should be improved by optimizing the transmission frequency in case of collision.

Table 1 shows an example of an identification step of a query tree algorithm that identifies four tags having four bits.

TABLE 1

Steps: the number of full identification

Query of reader: Query string generated from reader

Response: Tag ID and comparison result

Tag n: Unique ID of the tag

Query: Queries that are queued as a query from a reader

Memory: Tag ID value saved in reader memory after tag ID identification is completed

As such, when the query tree cycle is generalized at the node inside the query tree algorithm, a collision cycle of Equation 1 is required.

[Equation 1]

n + km-1

n: number of tags to identify

km: Number of non-working cycles (m changes depending on how many paths the tag is searched for when collision occurs)

Therefore, the conventional algorithm terminates after performing all queries in the queue. At the beginning of the identification process, the queue starts with Null, and the reader sends ε value corresponding to Null to the tag, and adds 0 and 1 whenever there is a collision, and the query depth becomes longer.

Query Tree Algorithm Energy Consumption As the depth of the query increases, the energy consumption of the query tree increases. In the case of a typical passive tag, since energy is supplied from a reader, optimizing energy consumption is a very important RFID performance factor. Therefore, there is a need to optimize the query of the reader and shorten the identification processor in order to minimize the energy consumption.

In order to solve the problems of the present invention, an object of the present invention is to provide an effective RFID collision avoidance control method in a homologous tag recognition environment that is differentiated according to the characteristics of the tag group to minimize the tag ID identification step. The purpose is.

In order to solve the above problems, according to an embodiment of the present invention, an efficient RFID collision avoidance control method in a homogeneous tag recognition environment initializes an initial queue to a "0" state, broadcasts to all tags, and tag signals in the initialization state. Receives the first step to select the identification group to be identified by the initial leader to query "0" or "1", and each time a collision occurs for the "0" query, create two 0-tags in the queue A second step of storing and recognizing a 0-series tag through an iterative query, and when the identification of the number of collisions of the 0-series query is completed, transmit a "1" query to check the number of 1-series tags through the collision count. As a solution means, the identification routine is repeated in the same manner as the 0-series query, and the identification is terminated when there are no more queries in the queue in which the query string is stored.

According to an embodiment of the present invention, the first to third steps may be a solution for identifying the 0-tag and the 1-tag in units of 3 bits.

According to an embodiment of the present invention, the second step or the third step is a solution for generating a stop signal to prevent further collision from the reader to the tag when the collision occurs and transitions to the initial state.

According to an embodiment of the present invention, the first to third steps may be applied to a logistics system and a location information grasping system.

As described above, the present invention is effective in identifying homologous tags and can reduce the time required by up to 50% compared to identifying heterologous tags.

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

2 is a flowchart illustrating a method for effectively controlling an RFID protocol in a homogeneous tag recognition environment according to an embodiment of the present invention. The method for controlling an efficient RFID protocol in the homogeneous tag recognition environment performs the following steps.

Initializing the initial queue to a "0" state, broadcasting to all tags, receiving a tag signal in the initialization state, selecting an identification group to be identified by the initial reader, and querying "0" or "1"; Whenever a collision occurs for the "0" query, generating two 0-series tags and storing them in a queue and recognizing the 0-series tags through a repeated query (S20), and the number of collisions of the 0-series queries When the identification is completed, send the "1" query to check the number of collisions by checking the number of collisions, repeat the identification routine in the same way as the 0-series query, and the queue containing the query string is no longer If there is no query, the step ends with identification (S30).

Hereinafter, the steps S10 to S30 will be described in more detail.

Initializing the initial queue to the "0" state and broadcasting to all the tags, receiving the tag signal in the initialization state to select the identification group to be identified by the initial reader to query "0" or "1" (S10) In order to prevent collision prevention of RFID in the homogeneous tag recognition environment, the initial queue is initialized to a "0" state and broadcasted to a mode tag.

In this state, when the tag signal is received, the reader first queries "0" in selecting an identification group to identify, and then queries "1" when the query "0" is dormant.

In particular, although the initial value transmits a null value during initial query transmission in the conventional technology, the cycle is greatly reduced by transmitting a zero value in the present invention.

Whenever a collision occurs for the "0" query, generating two 0-tags and storing them in a queue, and recognizing the 0-tags through an iterative query (S20), the "0" query of step S10 If the "0" query is collided, two zero-tags are created and stored in the queue. This process recognizes all zero-tags through an iterative query. Create and store in queue.

After the identification of the number of collisions of the 0-series query is completed, the number of 1-series tags is checked by identifying the number of collisions by transmitting a "1" query, and the identification routine is repeated in the same manner as in steps S10 and S20. When the query string is stored in the queue in which there are no more queries, the step of terminating identification (S30) recognizes the 1-series tag in the same manner as in the steps S10 and S20.

In step S10 to step S30 shows the tag information identification process of the query tree method as shown in [Table 2].

TABLE 2

Steps: the number of full identification

Query of reader: Query string generated from reader

Response: Tag ID and comparison result

Tag n: Unique ID of the tag

Query: Queries that are queued as a query from a reader

Memory: Tag ID value saved in reader memory after tag ID identification is completed

As such, the present invention relates to a differential identification method according to the nature of a tag group to be identified in order to optimize the tag ID identification step. For example, assuming that the tag to be identified by the identification tag is 0001, 0011, 1000, 1100 A bit sequence having a start bit of 0 is first identified based on the most significant bit. If there is no 0 sequence tag to be identified, a 1 sequence tag is identified. That is, it identifies by the same series depth first method.

In addition, the present invention is processed by a 3-bit query, and the initial value during the initial query transmission to minimize the cycle by transmitting a "0" value rather than a null value.

FIG. 3 is an exemplary view to help understand an RFID collision avoidance control method in the homogeneous tag recognition environment according to the present invention, and may be classified into an initial state, a reception state, a transmission state, and a human state.

That is, when checking the prefix in the initial state (10), query "0" for the first identification, and if there is no conflict in the reception state (20), query 1 to compare from the group where the collision occurs to the last node in 3 bit units. When a collision occurs in the transmission state 30 and transitions to the initial state 10, the reader generates a stop signal from the tag to block the transmission of bits after the collision, preventing further collisions, and then querying in units of 3 bits. By retransmitting, the present invention can be performed.

In addition, the steps S10 to S40 is preferably applied to a logistics system or location information grasping system by modularizing the program or algorithm.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features.

 Therefore, it is to be understood that the above description is only one embodiment, illustrative, and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

1 is a flowchart of a conventional query tree technique

2 is a flowchart illustrating a method for effectively preventing RFID collision in a homogeneous tag recognition environment according to the present invention.

Figure 3 is an exemplary view for helping to understand the effective RFID anti-collision control method in the homogeneous tag recognition environment of the present invention

* Explanation of Signs of Major Parts of Drawings *

10: Initial state

20: Receive status

30: Transmission status

Claims (4)

A first step of initializing an initial queue to a "0" state, broadcasting to all tags, receiving a tag signal in the initialization state, selecting an identification group to be identified by the initial reader, and querying "0" or "1"; A second step of generating two zero-tags and storing them in a queue each time a collision occurs for the "0" query and recognizing the zero-tags through an iterative query; And When identification is completed as much as the number of collisions of the 0-series query, the query is transmitted by checking the number of collisions by identifying the number of collisions, repeating the identification routine in the same way as the 0-series query, and query string. Efficient RFID protocol control method in a homogeneous tag recognition environment, characterized in that the third step of terminating the identification when there are no more queries in the stored queue. The method of claim 1, In the first to third steps, the 0-series tag and the 1-series tag are identified in units of 3 bits. The method of claim 1, The second step or the third step is an efficient RFID protocol control method in a homogeneous tag recognition environment, characterized in that for generating a stop signal to prevent further collision from the reader to the tag when a collision occurs and transition to the initial state. The method of claim 1, The first to third steps are effective RFID protocol control method in a homogeneous tag recognition environment, characterized in that applied to the logistics system, location information identification system.

Images