The PTF-Determinator: A Run-Time Method Used to Save Energy in NFC-Systems

Near Field Communication (NFC) in mobile devices like smart phones shows potential for applications like payment, identification, etc. Unfortunately the needed functionality increases the battery drain of the device. As a countermeasure power-management techniques are implemented. However, these techniques commonly don´t control the power transfer to the tag to prevent wasting energy. To adapt this transfer during run-time the properties of the reader, tag and the physical relation between them are needed. This paper proposes a method called PTF-Determinator. It determines the Power Transfer Function (PTF) during run-time and scales the provided power transfer accordingly to save energy. As a case study the PTF-Determinator is integrated into the tag-detection algorithm. Investigations are made regarding the power consumptions and timings through simulation and measurement on a development platform for mobile phones. The results show that 12% of the energy can be saved on average.