Studies On Air Interface Protocol And System Design For UHF RFID

The Ultra High Frequency (UHF) Radio Frequency Identification (RFID) technology located in the frequency band of 860–960 MHz has been regarded as one of the most promising technologies in the field of auto-identification. This paper addresses some of the key techniques in a UHF RFID system.Several recently published papers on UHF RFID have been briefly reviewed at the beginning of this paper, which present the state-of-the-art techniqes of UHF RFID. The basic theory of UHF RFID is discussed next, laying the fundamental for later discussions.Then the ISO/IEC 18000-6 Type C (EPCglobal Class-1 Generation-2, Gen-2) air interface protocol is detailedly analyzed, both at Physical (PHY) and at Media Access Control (MAC) layer. Some of most prominent advantages of the Gen-2 protocol over its early versions have been summarized after protocol evaluatioins. A channelization scheme in compliance with Chinese rules and regulations is proposed, followed by performance evaluations. Theoretical calculations show that the maximum query speed of a UHF RFID system under the Chinese regulations is 284 slots/s.Later a passive UHF RFID tag chip in compliance with the Gen-2 protocol is presented. The chip is designed as a process, voltage and temperature (PVT) variation-tolerant circuit in order to accommodate the fluctuation of the frequency from the local oscillator, which is anticipated to decrease the percentage of the failed chips and enhance the performance of the tags working under critical conditions. The tag chip has been fabricated using two different standard CMOS processes. The low cost design verification and test techniques for tag chip have also been introduced, by using which the test of our chips is accomplished. The sensitivity of the tag chips is better than -13 dBm.In the last section of this paper, a UHF RFID reader with a novel transceiver architecture is proposed, which is supported by a novel channelization scheme. Applying the novel reader and channelization scheme together, the scale of the reader's RF/analog section will decrease by 50%. The new channelizaion scheme will also increase the number of available readers in dense-interrogator environment by 100%, and increase the maximum query speed from 284 slots/s to 851 slots/s.