An Algorithm for Synthesizing Groups of Codes in an RFID Multiple Access System

Relevance. One of the problems that must be solved when creating RFID systems is the reader's multiple access to a group of tags located in a limited space, since the reading signal causes a one-time response of many tags, which leads to collisions (conflicts) of response signals. This problem has not been solved in relation to passive tags without a chip, based on surface acoustic wave technologies, the code of which is laid down during manufacture and cannot be changed during operation. The purpose of the study is to develop algorithms that allow synthesizing such groups of codes that would provide a controlled level of pairwise correlation of the selected label signals and thereby ensure the specified accuracy of label identification. The proposed algorithms are based on the procedures of code concatenation and inductive construction of groups of codes with a given volume and correlation level. For the algorithm for forming a group of codes with the required value of the correlation coefficient and the algorithm for combining groups of codes into complete and maximum groups, properties have been proven that confirm the possibility of using them to formulate tasks for preparing groups of labels on surfactants that would correspond to the number of objects requiring identification and the accuracy of their identification and taking into account the number of labels in the group, the conditions for the propagation of radio signals in the area of operation of the reader, the number of repeated readings of the label codes, as well as algorithms for joint data processing, received with all calculations.The methods used. Methods of coding theory and correlation analysis. Result. The developed algorithm is a tool for creating modern coding systems for surfactant labels. The scientific novelty. Well-known algorithms for multiple access in RFID systems are proposed in the GEN1 and GEN2 EPC Global standards, and assume that the tag has a chip and a power supply, which makes it possible to implement protocols for influencing the tag with a reader using special commands. The proposed multiple access algorithm is applicable for passive surfactant tags, including those moving at high speed and/or located in aggressive environments, since the tags do not use silicon technology compared to active RFID tags. Practical significance. The use of the proposed set of algorithms will increase the efficiency of marking systems by reducing the identification time of objects located in a confined space. 

radio frequency identification technology, object marking, code group, code correlation, code group synthesis algorithm