正交分頻多工系統中領航訊號位置分配及通道估測之研究

Study on Pilot Allocation and Channel Estimation for OFDM Systems

林正龍(Cheng-Lung Lin)

指導教授 ： 溫志宏

共同指導教授 ： 魏學文(Shyue-Win Wei)

國立暨南國際大學/科技學院/通訊工程研究所/碩士(2007年)

摘要

現今無線通訊系統中，適用於正交分頻多工系統的通道估測，在時變及多路徑傳播環境的假設下已被廣泛的研究。在正交分頻多工系統中，通道估測對於系統的表現是一個重要的考量。實際上，許多正交分頻多工系統會在子載波中傳送領航訊號來達到通道估測的目的。雖然領航訊號可以增加通道估測的正確性，但是卻佔據一些頻寬而且導致低的資料速率。
為了降低領航訊號數量，我們提出領航訊號極點配置法。它是利用前置訊號尋找通道響應的極點位置，並且插入領航訊號在極點位置上。在內插方法方面，我們則提出改良式權重內插法。它是利用三組內插方程式求解資料子載波的通道響應。

關鍵字

正交分頻多工 ； 通道估測 ； 領航訊號 ； 權重內插

並列摘要

Channel estimation for Orthogonal Frequency Division Multiplexing (OFDM) systems, which is widely used in today’s wireless communication systems, has been extensively studied under the assumption of time variation and multipath propagation [1]. Channel estimation has been an important issue for the performance of OFDM systems. In practice, pilot signals are transmitted by OFDM systems over some of their subcarriers for the purpose of channel estimation. While these pilot signals help increase the accuracy of channel estimation, they also occupy bandwidths and lead to lower data rate.
To minimize the amount of pilot signal, we propose the acme pilot allocation scheme. It uses preamble to find acme location of channel frequency response, and inserts the pilot signal on the acme location. From the viewpoint of interpolation scheme, we propose a modified weight interpolation scheme. It can solve the channel response of non-pilot subcarriers by using three interpolation equations.

並列關鍵字

OFDM ； Channel estimation ； Pilot signal ； Weight interpolation

參考文獻

[1]. R.W. Chang, "Synthesis of band-limited orthogonal signals for multichannel data transmission," Bell Syst. Tech. J., vol.45, pp.1775-1796, Dec. 1966.

[2]. B.R. Saltzberg, "Performance of an efficient parallel data transmission system," IEEE Trans. Comm., vol.15, pp.805-811, Dec. 1967.

[3]. R.W. Cheng, "Orthogonal frequency division multiplexing," U.S. patent 3,488,445, filed Nov. 14, 1966, issued Jan. 6, 1970.

[4]. W.Y. Zou and Y. Wu, "COFDM: an overview, " IEEE Trans. Broadcast., vol. 41, pp.1-8, Mar. 1995.

[5]. M.S. Zimmerman and A.L. Kirsch, "The AN/GSC-10 (KATHRYN) variable rate data modem for HF radio," IEEE Trans. Comm., vol.15, pp.197-205, Apr. 1967.