Multi-label anticollision method based on packet dynamic frame and binary tree search for RFID system

Abstract

The invention discloses a method for preventing collisions among a plurality of tags based on grouping dynamic frame and binary tree search in an RFID system. The method comprises a tag quantity estimation stage and a tag identification stage, wherein the tag quantity estimation stage is to finish the estimation of the quantity of unidentified tags; the tag identification stage is to select the optimal grouping number and the optimal frame size of each group according to the estimated value of the quantity of the unidentified tags, distribute the tags into a plurality of groups of frame periods for identifications in turn, and identify the tags in each group of time slots where collisions happen through the binary tree search so as to identify all the tags. The method combines the advantages of an ALOHA algorithm and a binary tree algorithm so that the quantities of collision time slots at the early stage of the identification and idle time slots at the late stage of the identification are greatly reduced, and the method has the advantages of simple structure, fast identifying speed and low tag power consumption, thus the method is quite suitable to be applied in the RFID system.

Description

technical field [0001] The invention relates to an anti-collision method applied in a radio frequency identification (RFID) system, in particular to a multi-label anti-collision method used in a RIFD system based on group dynamic frame and binary tree search. Background technique [0002] Radio Frequency Identification (RFID) is an automatic identification technology with the characteristics of real-time, fast and accurate collection. The RFID system consists of three parts: the reader, the tag and the application program. The reader and the tag communicate in a non-contact manner. There are three types of tags: active, semi-active and passive. Passive tags are widely used because of their simple structure and low cost. [0003] Due to the simplicity of the passive tag structure, the tag will respond to the reader immediately after receiving the command from the reader. However, when multiple tags respond to a reader at the same time, the mutual interference between the ta...

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Problems solved by technology

These two algorithms have their own problems: although the ALOHA algorithm has low complexity and low requirements for tags, there is a possibility that the tags will not be recognized all the time, and the performance of the algorithm is not good when the number of tags is large. The number of digits is limited; the advantage of the tree algorithm is that the recognition rate can reach 100%, but at the cost of increasing the complexity of the algorithm, which increases the power consumption of the reader and reduces the maximum recognizable distance of the tag

In addition, these two algorithms also have the phenomenon of time slot waste: ALOHA algorithm has a lot of idle time slot waste in the later stage of the identification process, because the frame length or the number of packets cannot be adjusted in real time with the identification of the label during the identification process Caused; the tree algorithm in the early stage of the identification process has more collision time slots due to the simultaneous response of more tags to the reader, and the performance of the query tree algorithm is also greatly affected by the distribution of tag IDs

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