Wireless firmware execution control in computational RFID systems

摘要

Current Computational RFID Tags (CRFIDs) are pre-programmed with only a single firmware instance in their flash memories for runtime operation where the functionality of CRFID is pre-determined by the firmware at the time of programming. As a result, the current CRFIDs require wired interface to re-program a new firmware which strictly limits their use to easy-to-reach places. We address this issue by remotely changing the behavior of CRFIDs by switching their firmware through commercial RFID reader and the EPC protocol, without demanding any hardware upgrades to CRFID tags or modification to EPC standard. We articulate the design, implementation and evaluation of FirmSwitch - a wireless scheme that equips CRFIDs with the capability of switching their firmware during runtime. This is achieved by wirelessly passing the encoded switching parameters to CRFID tag through RFID reader which leverages the tag to switch among firmwares and execute them for intended cycles. We further employ the schemes of pre-defined EPC and pre-calculated CRC for computational liberty and energy efficiency. For concept validation, we develop a User Interface to switch between four firmwares and extensively test our scheme. The results show that FirmSwitch offers a minimal energy overhead of 11.5nJ to 2.037μJ, and incurs a switching delay of 7.8 to 1498 μsec. As overall, our system achieves a success rate of 87% for an interrogation range of 0.5 meter.