Optimal Superimposed Pilot Selection for OFDM Channel Estimation

This paper presents an optimal strategy for utilizing superimposed pilots for OFDM channel estimation using Wiener filtering. An algorithm is formulated to determine the optimal rectangular set of time-frequency samples for channel estimation for a given complexity. The proposed scheme shows an improved performance at high Doppler frequencies. Moreover, the separable implementation of the 2D Wiener filter leads to a significant reduction in complexity with negligible degradation in channel estimation performance. The sensitivity of the proposed technique to channel statistical mismatches is also analyzed. Numerical results demonstrate the superior performance of the proposed technique compared to conventional selection of square set of time-frequency samples for Wiener-filter based channel estimation