Low Complexity Channel Tracking for Adaptive MMSE Channel Estimation in OFDM

In this paper, we introduce a channel parameter tracking method for adaptive OFDM MMSE channel estimation. Even though the MMSE estimation is one of the most accurate channel estimation methods, it requires several channel information including Doppler frequency, RMS (root mean squared) delay spread, and noise power. To implement the MMSE estimation, tracking of such parameters should be preceded. We first propose methods to track such parameters focusing on the estimation of Doppler frequency, and mention their performance and complexity. We then implement and simulate the adaptive MMSE estimation using these tracking schemes and analyze the estimator's performance in terms of channel tracking accuracy and BER performance. We conclude that the proposed channel parameter estimator tracks channel condition reliably in various channel conditions without significant increase in computational complexity and that BER performance of the adaptive MMSE estimation is better than that of a robust MMSE estimator by 5 dB in average.