Patent ID: 8115602

Claim:
A method for estimating the number of tags in a RFID system, comprising the steps of: a) at a reader, dividing tags in an identifiable area into a predetermined number of groups; b) identifying tags of a first group among the divided groups determined in step a), by applying a pilot frame L p to the first group; c) at the reader, calculating a collision probability P coll of tags of the first group after the pilot frame L p ends; and d) identifying unidentified tags of the first group, which are not identified for the pilot frame L p , by allocating an additional pilot slot L add at an end of the pilot frame L p or generating a new frame L 1 according to the collision probability P coll by comparing the collision probability P coll with a predetermined threshold P th , wherein if the collision probability P coll is smaller than the predetermined threshold P th , the additional pilot slot L add is allocated at the end of the pilot frame L p , to identify unidentified tags in the first group, and wherein if the collision probability P coll is larger than the predetermined threshold P th , unidentified tags in the first group are identified by generating the new frame L 1 after the pilot frame L p .