Harmonic-WISP: A passive broadband harmonic RFID platform

In conventional passive radio frequency identification (RFID) systems, downlink (reader to tag) and uplink (tag to reader) overlap on the same carrier frequency, which leads to severe self-jamming and reader collision problems. To resolve these issues, nonlinearity in passive RFID tags can be exploited to generate second or higher order harmonics for uplink data communication. The design of harmonic tag that allows efficient energy harvesting and harmonic generation at the same time is critical. We present Harmonic-WISP, the first harmonic RFID system integrated with the open-source wireless identification and sensing platform (WISP). Harmonic-WISP adopts a new routing strategy to ensure full power utilization in both energy harvesting and harmonic generation modes. The new platform can fundamentally eliminate self-jamming issues and can greatly reduce reader-to-reader interference. By integrating with WISP, the proposed platform can further allow flexible implementation and evaluation of efficient multiplexing and security protocols.