Analysis of Tag Loss Ratio in dynamic RFID systems

Radio Frequency Identification (RFID) systems promise a revolution in logistics and inventory applications. By means of wireless communication, a master device can detect and identify nearby electronic tags. Traditionally, the performance of RFID systems and their identification protocols has been analyzed for static configurations, that is, without considering incoming or outgoing tags, but just a fixed number of initially unidentified tags. However, many real scenarios cannot be consistently modeled that way. In this work we introduce a Markov model which allows us to study a dynamic RFID tag scenario, where a flow of tags is considered. This model can be used to compute the Tag Loss Ratio, which measures the ratio of outgoing unidentified tags to the incoming tags in the system, which is a critical metric in dynamic configurations. The analysis is carried out for two families of protocols used as medium access control in RFID, Framed Slotted Aloha and non-persistent CSMA. With the aim of validating the analysis predictions, we get simulation results, by means of a simulator. We evaluate a scenario similar to a real application, i.e. a mail control system based on RFID.