Measuring the interference at an RFID tag: Where does it have an impact?

In this paper we consider reader collisions in an Radio Frequency IDentification (RFID) system, especially how interference impacts the ability of a passive UHF tag to respond. We propose two innovative applications for using interference: 1) Blocking a tag response, and 2) cooperative reading of a tag. In order to investigate their applicability we focus on the experimental evaluation, where we impose interference on the download and uplink, respectively, and on both links simultaneously. The results are positive with respect to blocking the tag, where modulated Co-Channel Interference (CCI) shows most effective. Based on the measurements it is however not possible to read a tag cooperatively, i.e. the tag is unable to utilize the interference as an additional energy source.