An RF Wireless Power Transfer system to power batteryfree devices for asset tracking Internet of Things (IoT) and Wireless Sensor Networks (WSN) infrastructures are becoming more and more available and diffused. One major outcome is the development of new services that help to make everyday life easier and better. One of those to which this paper reserves special attention is asset tracking which refers to the method of tracking physical assets. This service is very well based on IoT infrastructure and, due to the enormous number of objects to be traced, desperately needs the availability of inexpensive tags with sensing capabilities, that can be conveniently monitored from a long distance and require no maintenance. For this, engineers are called to face very challenging issues. One of these is how to power a maintenancefree tag that consequently must be batteryfree. This paper deals with the investigation of a system based on radio frequency (RF) Wireless Power Transfer (WPT) that powers a batteryfree tag for asset tracking, in which the major challenge is that the WPT deals with dynamic objects at different speeds. The performances and key features of a system on chip (SoC) specifically designed to power a tag by means of RF WPT will be investigated. The aim is to provide a strategy and a model to design the infrastructure by providing the number of hotspots needed to perform successfully the identification of an asset. Validation of the model has been done by means of specific tests and experimental results are provided.

A UHF SemiPassive RFID System with PhotovoltaicThermoelectric Energy Harvesting for Wireless Sensor Networks A semipassive ultrahigh frequency (UHF) radio frequency identification (RFID) system is presented. The reconfigurable architecture of tag is proposed to be compatible with passive and active operating modes. The read range of RFID system and the lifetime of tag is increases by frequency locked onchip oscillator topology. The transceiver is implemented in 0.18xc2xb5m standard CMOS process. The sensitivity of tag is xe2x88x9218dBm for passive mode and xe2x88x9240dBm for active mode with 1.2xc2xb5W power consumption under the supply voltage of 0.8V. The output power is xe2x88x9210dBm for active transmitting mode and the power consumption is 450xc2xb5W under the supply voltage of 1V.