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研究生：	曾裕鴻 Tzeng, Yu-Hong
論文名稱：	引導信號輔助之OFDM系統時域與頻域的一維和二維通道估測 Pilot-Assisted 1D and 2D Channel Estimation for OFDM Systems
指導教授：	張名先 Chang, Ming-Xian
學位類別：	碩士 Master
系所名稱：	電機資訊學院 - 電腦與通信工程研究所 Institute of Computer & Communication Engineering
論文出版年：	2011
畢業學年度：	99
語文別：	英文
論文頁數：	35
中文關鍵詞：	正交分頻多工、通道脈衝響應、通道頻域響應
外文關鍵詞：	OFDM, channel impulse response, channel frequency response, channel responses
相關次數：	點閱：125 下載：3
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在詭異多變的無線通訊環境中，為了在終點接收端能夠等化通道效應以及減輕干
擾,我們必須要獲得通道資訊。一種最普遍的方法是估測通道頻率響應。我們在傳送
端傳送信號時在頻域上加入接收端已知的引導信號，對其他未插入引導信號的通道而
言，我們可以用最小迴歸曲線法和線性最小平方誤差法…等方法來估得。這種方法我
們取名為頻域估測法。
另一種方法是估測通道脈衝響應。在傳送時，我們在每個資料區塊之前傳送一個
脈衝，藉以獲得完整的通道資訊。這種方法我們叫他做時域估測法。
最後我們討論的是另一種方法，我們在接受端一次接收多個時間的通道響應在進
行演算。

For wireless communications, we need to estimate the channel in order to equalize or alleviate the distortion of the signals at the end receiver. The orthogonal frequency-division multiplexing (OFDM) transmission is a popular scheme used in the multipath wireless channels. We can use frequency-domain (FD) pilot symbols to estimate channel frequency response (CFR), or apply the time-domain (TD) unit pulse ahead of each OFDM block to estimate the channel impulse response (CIR).
In this thesis, we first study the one-dimensional (1D) channel estimation schemes based on FD pilot symbols and TD unit pulses. Then by applying the polynomials to model
the channel variation across time slots, we further give the two-dimensional (2D) channel estimation schemes based on FD pilot symbols and TD unit pulses, respectively. We
compare the resulted mean-square error (MSE) with the FD optimal linear minimum mean-squares error (LMMSE) algorithm. The 2D schemes jointly estimate more channel
responses, and they resulted smaller MSEs than the 1D schemes.

Contents
Chinese Abstract ............................................... I
English Abstract ................................... II
Acknowledgement………………………………………………….IV
List of Tables ................................... VII
List of Figures ................................. VIII
Chapter 1. ...................................... 1
Introduction ............................ 1
1.1 Motivation .................................. 1
1.2 Organization of this thesis .................. 2
Chapter 2. ...................................... 4
System and Channel Model ........................... 4
2.1 Orthogonal Frequency Division Multiplexing (OFDM) .... 4
2.2 Channel Model .................................... 6
2.2.1. Jake’s Rayleigh Fading Model .................. 6
2.2.2. Multipath Model ............................... 7
Chapter 3. ....................................... 9
One-Dimension Channel Estimation ................... 9
3.1 Frequency-Domain Approach for Channel Estimation .... 10
3.1.1. Linear Minimum Mean-Squares Error (LMMSE) ........ 12
3.1.2. Least-Squares Fitting Approach (LSF) ............ 14

3.1.3. Least-Square Fitting – Channel Impulse Response (LSF-CIR)........ 17
3.2 Time-Domain Approach for Channel Estimation ......... 18
3.2.1 Zero Forcing(ZF) ..........................20
3.3 Simulation of One-Dimension Approaches ............ 21
3.3.1 Parameter Adjustment .........................21
3.3.2 Simulation result .......................... 23
Chapter 4. ...................................... 25
Two-Dimension Channel Estimation ................... 25
4.1 2D Frequency-Domain Approach for Channel Estimation . 25
4.1.1 2D Linear Minimum Mean Square Error (2D LMMSE) .... 26
4.1.2 Least-Square fitting – Channel Impulse Response + Polynomial (LSF – CIR + poly.) .................... 28
4.2 2D Time-Domain Approach for Channel Estimation ...... 31
4.3 Simulation result of two-dimension approaches ....... 32
Chapter 5. ....................................... 34
Conclusion ...................................... 34
Bibliography ......................................... 35
                                    

[1] Y. Li, and X. Huang, “The Simulation of Independent Rayleigh Faders,” IEEE Trans. Commun., vol. 50, NO. 9, pp. 1503-1514, Sept. 2002.
[2] M. X. Chang and Y. T. Su, “2-D regression channel estimation for equalizing OFDM signals,” Proc IEEE 51th Vehicular Technology Conference, Tokyo, pp. 240-244, May 2000.
[3] M. X. Chang and Y. T. Su, “Model-based channel estimation for equalizing OFDM signal,” IEEE Trans. Commun., vol. 50, pp. 240-544, Apr. 2002.
[4] M. X. Chang and Y. T. Su, “Performance Analysis of Equalized OFDM System in Rayleigh Fading,” IEEE Trans. Commun., vol. 1, NO. 4, October 2002.
[5] M. X. Chang, “A new derivation of of Least-Square-Fitting principle for OFDM channel estimation,” IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 5, NO. 4, APRIL 2006.
[6] Peter Hoeher, Stefan Kaiser, and Patrick Robertson, “Two-Dimensional Pilot-Symbol- Aided Channel Estimation,” ISIT 1997, Ulm. Germany, June 29 - July 4
[7] Peter Hoeher, “TCM on Frequency-Selective Land-Mobile Fading Channels,” et al. – 1991
[8] Kun-Chien Hung and David W. Lin, “Pilot-Based LMMSE Channel Estimation for OFDM Systems With Power–Delay Profile Approximation,” IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 59, NO. 1, JANUARY 2010
[9] Die Hu, Lianghua He, and Luxi Yang, “Joint Pilot Tone and Channel Estimator Design for OFDM Systems,” IEEE COMMUNICATIONS LETTERS, VOL. 10, NO. 10, OCTOBER 2006

校內：2016-08-08公開
校外：2016-08-08公開

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