Robust LS channel estimation with phase rotation for single frequency network in OFDM

A channel estimation technique has been proposed with the least square (LS) based on comb-type pilots for orthogonal frequency division multiplexing (OFDM). An interpolator should be used to obtain the channel information between adjacent pilots for a comb-type pattern. However, an interpolation method causes additional errors due to the interpolation properties of not detecting long delayed paths and generating fictitious paths, OFDM has its strength in realistic possibility of constructing the single frequency network (SFN). However, synchronization and channel estimation errors are revealed by multi-path fading with long delayed paths in SFN channels. We propose a robust channel estimator overcoming the adverse effects of long delayed signals in SFNs. A new channel estimator is proposed with the interpolated LS by applying phase shifted samples in the frequency-domain. In particular, the proposed channel estimator is more robust to the single frequency network (SFN) whenever the delay spread is less than the cyclic prefix length. For a Rayleigh channel, the proposed estimator has an almost 3 dB gain comparing to conventional estimator