Innovative Joint CFO and Channel Estimation for RIS-Aided OFDM Systems

In this letter, we introduce an innovative approach to concurrently estimate the carrier frequency offset (CFO) and channel within reconfigurable intelligent surface-aided orthogonal frequency division multiplexing systems, which is assisted by our presented hybrid transmission protocol. The proposed scheme consists of two phases, eliminating the requirement for prior information on the maximum delay spread. Phase 1 includes the correlation-based CFO estimation and least-square-based channel estimation, and Phase 2 involves refining the coarse channel estimation from Phase 1 while mitigating the influence of noise. Theoretical analysis and computer simulations conducted validate its superior performance.