Channel Estimation for Adaptive Frequency-Domain Equalization

Frequency-domain equalization (FDE) is an effective technique for high-rate wireless communications because of its reduced complexity compared to conventional time-domain equalization (TDE). In this paper, we consider adaptive FDE for single-carrier (SC) systems with explicit channel and noise-power estimation. The channel response is estimated in the frequency domain following two different approaches. The first operates independently on each frequency bin while the second exploits the fading correlation across the signal bandwidth. Least-mean-square (LMS) and recursive-least-square (RLS) algorithms are employed to update the channel estimates. The noise power is estimated using a low-complexity algorithm based on ad hoc reasoning. Compared to other existing receivers employing adaptive FDE, the proposed schemes have better error-rate performance and can be used even in the presence of relatively fast fading.