Adaptive filtering for OFDM systems with frequency-domain oversampling

Orthogonal frequency-division multiplexing is sensitive to frequency offset between transmit and receive carriers. In this paper, frequency-domain oversampling is applied to tackle this problem. Our approach is motivated by the duality between time and frequency domains and the fact that time-domain oversampling has been successfully used to deal with timing errors. Theoretical minimum mean-square error (MSE) is first adopted as a performance measure to show that the proposed approach is robust against frequency offset, particularly when the frequency offset is within a limited range. Next, two commonly used adaptive filtering algorithms, namely, least-mean-square (LMS) and recursive least-squares (RLS), are discussed. Their performance is investigated in terms of convergence rate, steady-state MSE, and sensitivity to frequency offset.