ABSTRACT
CONTENTS 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Preliminaries on MAC in RFID Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3 Tag Collisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3.1 Deterministic Anticollision Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.3.2 Probabilistic Anticollision Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.3.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.4 Reader Collisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.5 Future Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
A radio frequency identification (RFID) system overcomes challenges of other identification systems including barcode systems, optical character recognition systems, smart cards, and biometrics (voice, fingerprinting, retina scanning) because it does not require line-of-sight communication, sustains harsh physical environments, maintains a costand power-efficient operation, and allows for simultaneous tag identification. As with other radio systems, RFID system requires Medium Access Control (MAC) protocols to bypass different types of collisions as they waste network resources and slow down the reading procedure. Further efficiencies are required in the case of RFID due to the tags’ limited capabilities in terms of processing and memory. The objective of this chapter is to provide an overview of state-of-the-art MAC procedures for an RFID system. We will
highlight the requirements of the different procedures in terms of signaling, memory and processing, and differentiate between the different proposals based on nominal merits. We will also identify how MAC protocols behave and affect the overall RFID system performance under assorted practical scenarios: for example, mobility and high reader or tag densities. Finally, we will dispense some thoughts on the potential integration of RFID and wireless sensor networks (WSNs).
