Study on improved slotted ALOHA algorithm to vehicle identification

RFID technology has been broadly applied in the transportation field. It can achieve wireless communication, thus, it can be used to the vehicle identification. But special case exists, such us it faces to more than one vehicle with different speed on the urban roads. If multiple labels respond at the same time, collision will happen. In this paper, according to the different distances between reader and vehicles, the vehicle are divided into different groups, then slotted ALOHA algorithm is used to identify the vehicles. In fact, it is an improved slotted ALOHA algorithm. A row of transistor amplifier which is printed within the label can turn on depending on the different induced voltage of the different distances. In addition the labels are grouped. Then different time delay is added to them, so they can be identified respectively. Simulation results show that new method, compared with the slotted ALOHA algorithm, has better identification effect.