Investigation of the Threshold of Second Carrier Sensing in RFID Deployment

Reader collision is not only limited to the interference between interrogator signals from different RFID readers, but to maintain low RFID tag cost, an RFID tag cannot filter a valid interrogation signal in a channel from another valid interrogation signal in another channel. Second Carrier Sensing is then introduced to solve this problem. This paper investigates the threshold values of second carrier sensing based on some common antenna placement configurations. Computations of these threshold values were carried out for different tag read ranges and different environmental factors. These threshold values are important to have effective enforcement of second carrier sensing