Improving the performance of UHF RFID communication in a small scale fading channel

Radio Frequency Identification (RFID) is mostly used in harsh environments were deep fades occur. Taking into account a small scale fading channel and the UHF RFID transmission specified by the the EPCglobal protocol a poor communication performance is observed. As the decoding process of the received information is not specified in this protocol, there is a significant potential of increasing the transmission performance with an appropriate decoding. This work will introduce a novel possibility to decode the received information. To match the decoding process with the transmission behavior, it will be shown how the system with a basic decoding scheme performs. Based on these results several modifications, like amplitude threshold, differential decoding and the modification of the used codes will be presented. These modifications take the channel behavior and its characteristic into consideration and lead to a performance gain of 26.2 dB using a certain encoding scheme. These results will be supported by the analysis of the bit error characteristic to demonstrate how the transmission is influenced by the modifications. Note that most modifications presented in this work can be implemented on the RFID reader side. Only the modification of the tag encoding sequence requires a change in the transponder structure.