Channel Estimation Based on Comb-Type Pilot Structure in OFDM System with Null Subcarriers

This paper analyzes the degradation effect of null subcarriers in orthogonal frequency division multiplexing (OFDM) systems on the time-domain maximum likelihood (ML) estimation performance. The analysis is used as the basis for a proposal for a new channel estimation method that can overcome performance degradation caused by null subcarriers. The accuracy of the proposed channel estimation is guaranteed by using an interpolation of the estimated channel in the frequency domain that comes before the channel estimation in the time domain.