To answer your question, I reached out to Steve Halliday, the president of High Tech Aid, a consulting firm specializing in automatic identification and data-collection (AIDC) technologies. According to Steve, pulse interval encoding (PIE) is frequency-independent, so it can be employed at any carrier frequency.
However, Steve notes, RFID standards for the air interfaces for low-frequency (LF), high-frequency (HF) and ultrahigh-frequency (UHF) transponders have been set for some time, and have been published as the ISO standards. “Some of these use PIE, and others don’t,” he states. “Why would you deviate from the standards?”
My advice is to research the ISO RFID standards to determine which specific ones utilize PIE.
—Mark Roberti, Founder and Editor, RFID Journal
Are There Any RFID Systems Used in the Home? »