A Scheme for Guaranteeing Fair Identification Delay in Gen-2 RFID Systems

In RFID System, when multiple tags respond simultaneously, a collision can occur. A method that solves this collision is referred to anti-collision algorithm. In Gen-2 RFID system, if the slot-count size varies during a query round due to the collisions, a new query round begins with a QueryAdjust command. Anti-collision algorithm of Gen-2 RFID system is simple. But, it has the tag starvation problem that a tag may never be successfully identified because its responses always collide with others. Therefore, this paper proposes a scheme to guarantee the fair identification delay. In the proposed scheme, if the slot-count value changes due to the collisions, the reader broadcasts a CollisionRound command to begin a collision round. During the collision round, the reader identifies only tags that occurred collision during the previous query round.