CHAPTER 12
DIRECTION OF ARRIVAL ESTIMATION BASED ON A SINGLE-PORT SMART ANTENNA FOR RFID APPLICATIONS
12.1 INTRODUCTION
Radio-frequency identification (RFID) systems play important roles in service industries, purchasing and distribution logistics, industry, manufacturing companies, and material flow systems [1]. Over the last few years, there has been an increasing demand for positioning capability for RFID applications. For example, many department stores use RFID system to manage goods in stock. These goods and items bear their RFID tags. It would be convenient for the sales staff to find the wanted items if the RFID readers have the positioning ability.
The most efficient way could be using smart antennas [2–4] at the RFID reader. In this chapter, we introduce a DOA finding algorithm that can be used at the RFID reader with smart antennas for RFID positioning applications. Various DOA finding algorithms include conventional methods, linear prediction methods, eigenstructure methods, and estimation of signal parameters via rotational invariance techniques (ESPRIT) [5]. All these methods are based on the digital beamforming (DBF) antenna arrays. In DBF, signals, which are received by individual antenna elements, are down-converted to baseband signals. ...
