A Low-Collision CSMA-Based Active RFID for Tracking Applications

Hardware complexity, active Tag power consumption, and Multiple Tags collection method are three critical parameters in all active radio frequency identification systems. In this work, both the MCU and RF operations are performed in single chip, which makes the Tag hardware smaller. A lot amount of energy is restored by setting Tags in the sleep mode in the most of times. Four commands are used for this system. At first, a unique ID is dedicated to each Tag by the ID allocation command. The polling command is implemented for searching desired Tags. By using of the ID clearing command, the object loses the passing permission for a given time or permanently. Utilizing the collection command, the information of all surrounding Tags are collected and monitored, simultaneously. The Carrier Sense Multiple Access method is used and its performance is evaluated. The maximum transmission range of 80 m at the output power of 4.5 dBm is obtained. An active Tag with unique ID is mounted on each vehicle. Receiver sensitivity of 97 dBm and current consumption of 1 \(\mu \text{ A}\) in the sleep mode and 29.6 mA in the active mode are reported.