一種適用於多重輸入輸出之正交時頻空間、正交時序多工及正交分頻多工系統的通道通用估測方法

Abstract

本論文探討適用於多重輸入多重輸出之正交時頻空間、正交時序多工與正交分頻多工系統的通道估測方法。針對高速移動環境下通道估測與等化的挑戰，提出一種基於插值的導頻通道估測方法，結合區塊式最小均方誤差等化，能有效降低運算複雜度並維持優異的偵測性能。 此外，本研究針對多重輸入多重輸出系統提出一種僅需單一導頻的通道估測架構，利用曲線擬合與符號交替技術，有效降低導頻與保護間隔所需的開銷。透過一階、二階及三階的曲線擬合法，分析其在不同移動速度下的估測準確性，並提出多種修正策略以改善高速移動時的估測誤差。 模擬結果顯示，所提出的方法在維持良好誤比特率與均方誤差表現的同時，亦能有效降低系統的導頻開銷，特別是在中低速移動環境下展現出顯著優勢。

This thesis investigates channel estimation techniques for Multiple-Input Multiple-Output (MIMO) systems based on Orthogonal Time Frequency Space (OTFS), Orthogonal Time Sequency Modulation (OTSM), and Orthogonal Frequency Division Multiplexing (OFDM). To address the challenges posed by rapidly time-varying channels in high-mobility scenarios, an interpolation-based pilot-assisted channel estimation method combined with blockwise Minimum Mean Square Error (MMSE) equalization is proposed, achieving reduced computational complexity while maintaining reliable detection performance. Furthermore, a novel pilot-efficient channel estimation framework for MIMO OTFS/OTSM systems is developed, employing curve fitting and sign-alternating schemes to mitigate pilot contamination and reduce guard interval overhead. First-order, second-order, and third-order curve fitting methods are explored, and various refinement strategies are proposed to enhance estimation accuracy under high Doppler conditions. Simulation results confirm that the proposed methods achieve favorable Bit Error Rate (BER) and Normalized Mean Square Error (NMSE) performance while significantly reducing pilot overhead, particularly in low to moderate mobility scenarios.