Pilot Subcarrier Based Channel Estimation in OFDM System

Channel estimation is essential at receiver for accurate channel state information in orthogonal frequency division multiplexing (OFDM) system. Pilot subcarriers are used in pilot-assisted estimation for the channel. In this paper, we propose an algorithm for mapping 4-bit pilot bits into gray-coded complex constellation and a technique to insert gray-coded complex pilot symbols into OFDM stream before transmission for proper channel estimation. Gray-coded pilot symbol constellation mapping and DFT-based time-varying system is implemented in Matlab using LS estimation techniques. Our proposed algorithm illustrates superior performance over the cross-entropy optimization, stochastic sequential search (SSS), and stochastic parallel search (SPS) for time-varying system.

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