Crucial or Unnecessary? Analysis on Phase Differential in Holographic SAR RFID Localization

The development of synthetic aperture radar (SAR) radio frequency identification (RFID) localization technology has taken the RFID based indoor localization research to a new level, among which the holographic localization is the most typical approach. Holographic SAR RFID usually performs phase differential to deal with the problem of unknown initial phase. However, problems with regard to the phase differential have emerged in prior literature, some of which make the localization system perform extra but useless efforts, some affect the comprehensibility of the algorithm, and some even reduce the reliability of localization results. Therefore, the analysis of phase differential is very helpful for researchers and practitioners to complete and improve their work. In this paper, several conclusions concerning the phase differential are drawn and analyzed, which are verified by real experiments.