A group-based ternary query splitting protocol for tag identification in RFID systems

For large scale RFID systems, the tag collision is a significant issue, which can decline the identification efficient and prolong the identify time. In some applications, such as object tracking, locating and monitoring etc., the reader needs to repeatedly identify the same tags existing within its read range, which will bring some new collisions with the random mobility of passive tags. To identify tags fast, we propose a group-based ternary query splitting protocol (GTQS), which is suitable for large scale and mobile RFID systems. Based on the distance between the reader and tags, a grouping structure is built to decrease the number of tags participating in one identification process, which can effectively reduce the occurrence of collisions. Using the blocking and ternary resolution techniques, a new identification process procedure is designed to prevent the collisions from the staying tags and the mobile tags, in which the reader can use one query to identify at most three tags simultaneously. The simulation and performance analysis results show that our protocol has better performance than the existing protocols in shortening identification delay with varying the status ratio and the number of tags.