Tag estimation method and tag identification method for RFID system
First Claim
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1. 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 Lp to the first group;
c) at the reader, calculating a collision probability Pcoll of tags of the first group after the pilot frame Lp ends; and
d) identifying unidentified tags of the first group, which are not identified for the pilot frame Lp, by allocating an additional pilot slot Ladd at an end of the pilot frame Lp or generating a new frame L1 according to the collision probability Pcoll by comparing the collision probability Pcoll with a predetermined threshold Pth,wherein if the collision probability Pcoll is smaller than the predetermined threshold Pth, the additional pilot slot Ladd is allocated at the end of the pilot frame Lp, to identify unidentified tags in the first group, andwherein if the collision probability Pcoll is larger than the predetermined threshold Pth, unidentified tags in the first group are identified by generating the new frame L1 after the pilot frame Lp.
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Abstract
Provided are a tag estimation method and a tag identification method using the same in a RFID system. In the tag estimating method, a reader divides tags in an identifiable area into a predetermined number of groups. Tags are identified by applying a pilot frame Lp to a first group among the divided groups. The reader calculates a collision probability Pcoll of tags after the pilot frame ends. Then, unidentified tags of the first group, which are not identified for the pilot frame, are identified by allocating an additional pilot slot Ladd at an end of the pilot frame or generating a new frame L1 according to the collision probability Pcoll.
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Citations
13 Claims
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1. A method for estimating the number of tags in a RFID system, comprising the steps of:
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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 Lp to the first group; c) at the reader, calculating a collision probability Pcoll of tags of the first group after the pilot frame Lp ends; and d) identifying unidentified tags of the first group, which are not identified for the pilot frame Lp, by allocating an additional pilot slot Ladd at an end of the pilot frame Lp or generating a new frame L1 according to the collision probability Pcoll by comparing the collision probability Pcoll with a predetermined threshold Pth, wherein if the collision probability Pcoll is smaller than the predetermined threshold Pth, the additional pilot slot Ladd is allocated at the end of the pilot frame Lp, to identify unidentified tags in the first group, and wherein if the collision probability Pcoll is larger than the predetermined threshold Pth, unidentified tags in the first group are identified by generating the new frame L1 after the pilot frame Lp. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for identifying tags in a RFID system, comprising the steps of:
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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 Lp to the first group; c) at the reader, calculating a collision probability Pcoll of tags after the pilot frame ends; d) identifying unidentified tags of the first group, which are not identified for the pilot frame, by allocating an additional pilot slot Ladd at an end of the pilot frame or generating a new frame L1 according to the collision probability Pcoll by comparing the collision probability Pcoll with a predetermined threshold Pth, wherein if the collision probability Pcoll is smaller than the predetermined threshold Pth, the additional pilot slot Ladd is allocated at the end of the pilot frame Lp, to identify unidentified tags in the first group, and wherein if the collision probability Pcoll is larger than the predetermined threshold Pth, unidentified tags in the first group are identified by generating the new frame L1 after the pilot frame Lp; e) deciding an optimal frame size Lopt based on the number of tags of the first group, which are estimated through steps a) to d); f) identifying tags in a second group among the divided groups determined in step a), by applying the decided optimal frame size Lopt; and g) identifying tags of a current group among the divided groups determined in step a), by applying an optimal frame size Lopt decided based on a number of identified tags in a previous group among the divided groups determined in step a) and repeating step g) for identifying tags in remaining groups among the divided groups determined in step a) after the second group. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification