Patent ID: 8779899

Claim:
An RFID interrogator retransmitting a command depending on a collision situation, comprising: a collision diagnosis unit that analyzes data of a received signal received during a receive time in correspondence with a transmitted signal from an RF communication unit that transmits and receives signals to and from one or more tags, the collision diagnosis unit verifies whether a collision occurs in the received signal, and diagnoses a collision type depending on an analysis result of the data of the received signal; in response to the determination that the collision has occurred, a collision resolution unit retransmits a command depending on the collision situation to the tag through the RF communication unit on the basis of the occurrence of the collision and the collision type that are received from the collision diagnosis unit; wherein the collision resolution unit includes a situational command retransmission portion that determines whether the command will be retransmitted on the basis of the occurrence of the collision and the collision type, and a random wait time calculation portion that calculates a random wait time for retransmitting the command; and wherein when the collision type is of at least a first type, the command is retransmitted, and when the collision is of at least a second type, the command is not retransmitted.