Patent ID: 8217761

Claim:
A method for preventing reader collision including a multiple-readers-to-tag interference which happens when more than one radio frequency identification (RFID) reader tries to access to one tag and a reader-to-reader interference, the method comprising: detecting the number of readable readers within a readable region of a target reader; calculating the number of peripheral readers within the readable region and a collision region of the target reader by using the number of the readable readers; forming one frame with time slots of which the number equals to the number of the peripheral readers; and setting a present time slot of the target reader to be one of the time slots, the one being selected randomly in the time slots, wherein calculating the number of peripheral readers, comprising: estimating the number of the collision readers within the collision region; and adding the number of the readable readers to the number of the collision readers to obtain the number of the peripheral readers, wherein estimating the number of the collision readers, comprising: multiplying the number of the readable readers to a ratio of an area of the collision region to an area of the readable region to obtain the number of the collision readers.