RFdesk: Record Your Objects on Desktop Using COTS RFID Devices Contactlessly Desktop is a reliable and amicable object carrier that accompanies us in our daily life, while working, eating and even entertaining. In this work, we devise a contactless but accurate object tracking system on desktop with commercial RFIDs. Comparing with conventional vision or acoustic based solutions, our system needs less computational resources and could be mucheasier for deployment. Moreover, ours could record the true positions for each device instead of the relative positions delivered in most of the previous studies. To this end, recording the useru0027s access to the object on the desktop allows the user to interact with the smart device with simple actions. We present RFdesk, a contactless object location system that accurately locates every objects on the desktop. However, compare to tracking object withcontacted tag, several challenges are tackled before we make the system work. First of all, the signal employed for contactless tracking gets reflected twice which is thus much weaker, making the signal more susceptible to environmental noise and multipath. Another wellknown challenge for contactless tracking is multitarget tracking as the signals reflected from multiple targets get mixed and interact. Extensive experiments show that RFdesk canflexibly deploy devices and tags, antennas, and localization itemscan be deployed on different planes. A median error of 3cm can be achieved for target tracking without attaching tags to the targets, even if there are 4 positioning objects on the desktop. Moreover, the average localization error can still be kept within 5.6cm outperforming the stateoftheart systems by 100%.

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.