Study about the Influence of Tag Collision over the Identified RFID tag signals

In passive UHF RFID systems, tag collisions occur when multiple tags transmit simultaneously to reader. Due to the mixture of waves, the reader cannot differentiate any information and, consequently, more signals must be retransmitted until all tags are successful identified. The high traffic of RFID signals in real indoor environments can accentuate the multipath effect. In this letter, we conduct measurements in laboratory to study the influence of tag collision over the tag signals identified by the reader. From two scenarios based on high and low probability of tag collision, we evaluate the signal quality of successfully identified tags.