Design of implementation-efficient channel estimation filter for wireless OFDM transmission

The detection performance of coherent OFDM receiver significantly depends on the accuracy of channel estimation. The accuracy of channel estimation can be improved by properly post-processing the channel estimate using a so called channel estimation filter (CEF). Linear minimum mean-squared error (MMSE) filter is optimum as the CEF, but it may not practical due to implementation complexity. We consider the use of a reduced-complexity CEF whose tap coefficient is real valued and symmetrically weighted (RSW). The optimum RSW CEF is analytically designed using the multi-path intensity profile and SNR of the channel. We also propose a method to adapt the coefficient of the RSW CEF to the channel condition. Numerical results show that the proposed RSW CEF can provide channel estimation performance comparable to that of a linear MMSE filter, while significantly reducing the computational complexity. In addition, the proposed RSW CEF can provide performance robust to unknown timing offset with a fractional dB loss compared to the optimum one.