Full-scale Testing and Performance Evaluation of an Active RFID System for Positioning and Personal Mobility

This paper presents a series of tests and analyses undertaken to investigate the performance capabilities of an active RFID system (Freaquent (R)) for asset tracking and personal mobility. The RFLD system was tested exhaustively considering a number of user requirements including maximum operating distance, antenna orientation, position accuracy, the influences caused by nearby objects and the operating environment. For this purpose, various positioning techniques were applied based on the lateration and fingerprinting positioning concepts. Analysis revealed that the lateration technique is sensitive to operational environment; however, as long as a representative "RSS to distance" model is established the method can deliver accuracies of the order of 0.7 m at unobstructed line-of-sight conditions. Location fingerprinting has shown that large temporal variations can occur partly which effect the radio maps of RSS distributions significantly. Thus, RSS training measurements have to performed at regular intervals to guarantee acceptable positioning accuracies on the meter-level.