Energy efficiency by using field strength scaling for multi-transponder applications

The rising demand for Near Field Communication (NFC), which uses the RFID technology, drives the market to deliver up to 500 million devices in 2014. The applications for RFID spread from simple identification to wireless gateways for embedded systems. The integration of this RFID-Reader in smart phones are an example for mobile RFID-Systems. Unfortunately, this integration leads to a decreased smart phones battery life, through the increased power consumption. To decrease this consumption, power management techniques like magnetic field strength scaling have been proposed. This technique adapts the amount of transferred power to the requirements of the transponder. This technique does not consider multiple transponders in transmission range. Therefore, this paper proposes an adapted version of the reader´s transponder-detection process using magnetic field strength scaling to reduce the reader´s battery drain. The adapted version has been implemented by two novel methods. These two methods have been experimentally verified by a case study. The potential of needing less battery drain is evaluated and compared to different possible implementations. In this case study, the battery drain needed by the RFID-Reader can be reduced by up to 34% using magnetic field strength scaling for multiple transponders.