Performance of slotted aloha anti-collision protocol for RFID systems under interfering environments

Abstract

Radio Frequency Identification (RFID) is a wireless technology that has replaced barcodes. This technology is used in today’s world to track assets and people. An RFID system consists of three components: the tag, the reader, and the middleware. The RFID tag stores data, the reader is used to identify the data stored in the tag or write data to the tag, and the RFID middleware is the application that connects the data that the reader obtains from the tag with the company inventory or database. Unlike barcode readers, an RFID reader is capable of reading multiple tags located in its range. When this occurs, the probability of tag collision at the reader’s end is high. To avoid tag collision, anti-collision protocols are used. Slotted Aloha is one of the main anti-collision protocols used with RFID. This thesis proposed a mathematical model and a simulator to analyze the performance of the Slotted Aloha protocol without interference. Tag detection is directly related to tag signal strength detected by the reader. Radio Frequency signals behave differently when different objects are present in the environment. For example water absorbs radio signals. When water is present in the environment, tag detection will not be successful, since radio signals will be absorbed by the water. Therefore, water is considered an interference factor in tag detection. This thesis also proposed a mathematical model and a simulator to analyze the performance of the Slotted Aloha protocol with interference. A comparison of both sets of results shows that the proposed mathematical model and the simulator are accurate. Results of the analysis show that the time required to identify tags with interference is longer than the time required to identify tags without interference.