Effect of Channel Estimation on RFID Tag Reading Error and Throughput Performance

Conference: Smart SysTech 2015 - European Conference on Smart Objects, Systems and Technologies
07/16/2015 - 07/17/2015 at Aachen, Germany

Proceedings: ITG-Fb. 259: Smart SysTech 2015

Pages: 7Language: englishTyp: PDF

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Elshabrawy, Tallal; Ashour, Mohamed; Sherin, Ezzeldin (Information Engineering and Technology, German University in Cairo, Cairo, Egypt)

UHF EPC Gen 2 RFID systems use a random medium access control to manage the reading of multiple RFID tags. To enable RFID readers to read a large number of tags in a small time, it is required to increase the throughput. At a given time slot the reader can receive short address message (RN16) from one or more tags. Most of existing research assumes that if a single message is received, it will be decoded correctly and if multiple messages are received within a given time slot, collision will occur and none of the messages will be received. These assumptions ignore the possibility of incorrectly receiving a single tag message because of the channel and the underlying signal-to-noise ratio operating conditions and also overlook the possibility of decoding one of the colliding tag messages when collision occurs. In both cases the ability to correctly decode the tag will depend on the signal to noise ratio, the channel and the level of channel estimation employed. Channel estimation is challenging in RFID systems as the same tag signal has to be used for both decoding the information and estimating the channel. This paper provides an analytical evaluation for the probability of no error in the RN16 messages under both single tag slot and collision slot conditions. The impact of such probability of successful tags decoding on the throughput is presented for three levels of channel estimation: no channel estimation, carrier estimation and full estimation of the channel. The analysis is verified using simulation and the effect on throughput is presented.