Robust Signal Detection in Passive RFID Systems

This paper investigates a robust signal detection scheme for the uplink communication in radio frequency identification systems. An optimum maximum-likelihood sequence detector (MLSD) scheme and a sub-optimum sliding correlation detection scheme are proposed for differential bi-phase codes. The MLSD scheme has 3 dB performance improvement w.r.t. the single symbol ML detector. However, these algorithms are not robust to symbol timing errors, and the performance decreases fast already for few error samples. The robustness to timing errors can be significantly improved by a sub-optimum scheme performing one or more symbols sliding correlation detection.