通道估計器通常對於實際通道的長度是未知的,設計時常以通 道的最大可能長度作通道估測。本篇論文針對這種在估計器中,含有 多餘估計參數的情況,討論其對於估計準確度的影響,並依此推導出 最佳估計器的訓練序列之設計準則。估計的方法為最大可能估計,精 確的數學分析公式被提出,並與電腦模擬做比較,驗證出理論與實際 模擬結果吻合。此結果可作為將來進一步在改進通道估計準確度的先 導研究,藉以提出新的通道參數估計器。 The practical channel length for a channel estimator is usually unknown. The maximum possible channel length is therefore assumed a priori. In this paper, we explore the effect of channel information redundancy on the channel estimation accuracy in orthogonal frequency division multiplexing (OFDM) systems. The optimum training sequence for channel estimation is discussed. Theoretical analysis and Monte Carlo simulation are compared and show great agreement. Maximum-likelihood (ML) estimation is used for the channel estimation. The study leads to a novel channel estimator design.