Joint Symbol Timing and Frequency Offset Estimation Using Zero Correlation Zone Sequence for RIS-assisted OFDM Systems

Every communication system necessitates synchronization between the transceiver pair to ensure optimal performance at the receiver end. Reconfigurable intelligent surface (RIS)-assisted orthogonal frequency division multiplexing (OFDM) systems are also susceptible to the synchronization error, i.e., symbol timing offset (STO) and carrier frequency offset (CFO), Similar to conventional OFDM systems. Various techniques have been developed for estimating STO and CFO for OFDM systems. However, these existing methods do not specifically address the combined impact of STO and CFO in RIS-assisted OFDM systems. Motivated by this, we propose a joint STO and CFO estimator based on the zero correlation zone (ZCZ) sequence for RIS-assisted OFDM systems operating in a Rayleigh fading environment. The ZCZ sequences show ideal correlation properties in a zone. In terms of mean squared error (MSE), simulation results demonstrate that the proposed method outperforms other existing techniques. The bit error rate (BER) plot demonstrates that the proposed method is robust and effective against varying CFO and STO values after compensation.