Asynchronous reception of 2 RFID tagsAsynchronous reception of 2 RFID tags Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2022-10-212021enThis research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH - CREATE - INNOVATE (project code: T1EDK-03032).Commercial radio frequency identification (RFID) readers have to resolve collisions between tags, without sacrificing throughput. This work proposes a Viterbi joint sequence detector as well as a 2-symbol joint tag information detector that can resolve a collision between two tags in the physical layer. In sharp contrast to prior art, the proposed closed-form signal model takes into account the asynchrony level between the two collided tag responses, which is not uncommon with commercial, low-cost RFID tags that follow industry’s Gen2 protocol. The asynchrony is considered as the time offset τ between the beginnings of the two tags’ responses and is modeled through a derived shaping matrix that depends on the delayed tag information. Performance evaluation of the proposed detectors with simulated data under Ricean fading, as well as experimental data with software-defined radio, reveals improved performance compared to prior art, under various operating regimes. It is also shown that for different values of the parameter τ , BER does not present a monotonic behaviour. As a collateral dividend, it is found that clustering techniques on the filtered received signal should explicitly take into account the time offset τ , since the latter modifies the number of observed clusters.http://creativecommons.org/licenses/by/4.0/IEEE Transactions on Communications6985243-5254 Skyvalakis Konstantinos Σκυβαλακης Κωνσταντινος Bletsas Aggelos Μπλετσας Αγγελος Institute of Electrical and Electronics Engineers Asynchronous detection Symbol synchronization Viterbi FM0 RFID Gen2