R2: Over-the-air reprogramming on computational RFIDs

In recent years, Computational RFID tags (CRFIDs) have emerged as viable software-defined platform for academic research and experimentation. In addition to EPC protocol, these tags perform sensing and computation through power scavenging. However, existing CRFIDs are pre-programmed to execute a specific firmware whereas programming tools comprising wired interface and PC-based software are required to erase, modify or reprogram the tag. Such limitation demands an over-the-air (OTA) scheme which can wirelessly upgrade or reprogram the CRFID tags while following the EPC protocol. We present the design, implementation and evaluation of R2 — the first OTA reprogramming scheme for CRFID tags without requiring any modification to EPC protocol, or an upgrade to RFID reader or CRFID tag. We develop a User Interface and realize our scheme on three platforms which include both software-defined as well as chip-based CRFIDs, i.e., WISP5.1 and Optimized WISP (Opt-WISP), and Spider tag. It also includes both the FLASH and FRAM based micro-controller memories. We evaluate our scheme from three aspects: time and energy overhead for reprogramming operation itself; overall system delay to verify the compatibility of R2 with EPC protocol; success rate in line with interrogation range. We foresee our endeavour to offer viability of OTA reprogramming and upgrade for CRFID systems.