臺灣博碩士論文加值系統

Nowadays, direct-conversion radio frequency (RF) receivers become
more appealing due to its cost advantage. However, orthogonal frequency division multiplexing (OFDM) systems with direct-conversion RF receivers are very sensitive to non-idealities at the front-end of receiver, such as I/Q imbalance and carrier frequency offset (CFO). These non-idealities at the receiver result in inter-carrier interference (ICI). Accurate estimates of the non-idealities and
channel response are required in OFDM systems.
This thesis studies the CFO estimation for OFDM systems with multiple transmit antennas. The thesis consists mainly of two parts. In the first part, we consider OFDM systems with 2 transmit antennas. The Alamouti code is employed at the transmitter and both ST-OFDM and SF-OFDM systems are considered. For these systems with 2 transmit antennas, we extend two known blind CFO estimation algorithms (which were derived for OFDM systems with one transmit antenna) to solve the CFO estimation problem in ST and SF-OFDM systems. IN the second part, we consider OFDM systems with 3 transmit antennas. Orthogonal space time block codes (OSTBC) codes are used to encode the single at the transmitter. For this system, we derive a new blind CFO estimation algorithm. The idea is to exploit the fact that the rate of OSTBC is only 3/4. We show how to exploit the redundant information in OSTBC for blind CFO estimation. Moreover, the problem of I/Q imbalance is also consider in the second part. At the end, we also provide numerical simulation to verify the performance of the proposed methods.

Contents
List of Figures ix
Abstract xi
Acknowledgements xiii
1 Introduction 1
2 I/Q Imbalance and Carrier Frequency O set in OFDM Systems 5
2.1 Introduction to OFDM Systems . . . . . . . . . . . . . . . . . . . . . 6
2.2 The Phenomenon of I/Q Imbalance and CFO . . . . . . . . . . . . . 10
2.3 Compensation of I/Q Imbalance and Carrier Frequency O set . . . . 14
2.4 Simulation Result and Comparison . . . . . . . . . . . . . . . . . . . 17
2.5 Concluding Remark . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3 CFO in Alamouti-coded OFDM systems 21
3.1 Introduction to Orthogonal Space Time Block Codes . . . . . . . . . 22
3.2 Space-Time OFDM Systems . . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Space-Frequency OFDM Systems . . . . . . . . . . . . . . . . . . . . 26
3.4 CFO in Alamouti-coded OFDM systems . . . . . . . . . . . . . . . . 28
3.5 Simulation Result and Comparison . . . . . . . . . . . . . . . . . . . 29
3.6 Concluding Remark . . . . . . . . . . . . . . . . . . . . . . . . . . .. .32

4 Blind CFO Estimation Algorithms for Alamouti-coded OFDM Systems with 2 Transmit Antennas 33
4.1 Review of FA Method for CFO Estimation in SISO OFDM Systems . 34
4.2 Extension of the FA Method to Alamouti-coded OFDM Systems with
2 Transmit Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.1 ST-OFDM Systems . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.2 SF-OFDM Systems . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.3 Simulation Result and Comparison . . . . . . . . . . . . . . . 39
4.3 Review of Diagonality Method for CFO Estimation in SISO OFDM
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.4 Extension of the Diagonality Method to Alamouti-coded OFDM Systems
with 2 Transmit Antennas . . . . . . . . . . . . . . . . . . . . . 44
4.4.1 ST-OFDM Systems . . . . . . . . . . . . . . . . . . . . . . . . 44
4.4.2 SF-OFDM Systems . . . . . . . . . . . . . . . . . . . . . . . . 48
4.4.3 Simulation Result and Comparison . . . . . . . . . . . . . . . 48
4.5 Concluding Remark . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5 Blind CFO and I/Q Imbalance Estimation Algorithms for OSTBC-OFDM Systems with 3 Transmit Antennas 53
5.1 Review of OSTBC-OFDM Systems with 3 Transmit Antennas . . . . 54
5.2 CFO and I/Q Imbalance in OSTBC-OFDM Systems with 3 Transmit
Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.2.1 CFO E ect Model . . . . . . . . . . . . . . . . . . . . . . . . 58
5.2.2 I/Q Imbalance E ect Model . . . . . . . . . . . . . . . . . . . 59
5.2.3 Simulation Result and Comparison . . . . . . . . . . . . . . . 60
5.3 Blind CFO Estimation Algorithms Based on Rank Criterion . . . . . 62
5.3.1 Proposed CFO Estimation Method Using Rank Criterion . . . 62
5.3.2 Approximation Using Curve Fitting . . . . . . . . . . . . . . . 63
5.3.3 Simulation Result and Comparison . . . . . . . . . . . . . . . 64
5.4 Blind I/Q Imbalance Estimation Algorithms Based on Rank Criterion 69

5.4.1 Blind Estimation for Independent I/Q Imbalances . . . . . . . 69
5.4.2 Blind Estimation for Dependent I/Q Imbalances . . . . . . . 71
5.4.3 Simulation Result and Comparison . . . . . . . . . . . . . . . 72
5.5 Concluding Remark . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6 Conclusion 79
Bibliography 81

Bibliography
[1] 3GPP TS 36.211 v8.0.0. 3-rd Generation Partnership Project Technical Speci cation Group Radio Access Network Evolved Universal Terrestrial Radio Access(EUTRA)
Physical channels and modulation (Realease 8),Sept. 2007.
[2] European Telecommunication Standards Institude, Digital audio broadcasting (DAB) to mobile protable and fixed receiverd," EST 300 401, 1994.
[3] European Telecommunication Standards Institude, Digital vedio broadcasting;framing, structure, channel coding and modulation for digital terrestrial television
(DVB-T)," EST 300 744, 1997.
[4] Lawrence Der, and Behzad Razavi, A 2-GHz CMOS image-reject receiver with LMS calibration," IEEE J. Solid-State Circuits, vol. 38, no. 2,pp. 167-175, February
2003.
[5] Pengfei Zhang, Thai Nguyen, Chris Lam, Doug Gambetta, Chet Soorapanth, Baohong
Cheng, Siegfried Hart, Isaac Sever, Taou k Bourdi, Andrew Tham, Behzad Razavi1, A direct conversion CMOS transceiver for IEEE 802.11a WLANs," in IEEE Int. Solid-State Circuits Conf. Dig Technical papers, February 2003.
[6] Darryl Dexu Lin, Ryan A. Pacheco, Teng Joon Lim, and Dimitrios Hatzinakos,
Joint estimation of channel response, frequency o set, and phase noise in OFDM,"
IEEE Transactions on Signal Processing, vol. 54, no. 9, September 2006.
[7] Qiyue Zou, Alireza Tarighat, and Ali H. Sayed, Compensation of phase noise in
OFDM wireless systems," IEEE Transactions on Signal Processing, vol. 55, no. 11,
November 2007.
[8] Songping Wu, and Yeheskel Bar-Ness, OFDM channel estimation in the presence
of frequency o set and phase noise," IEEE International Conference on Commu-
nications, vol. 5, pp. 3366-3370, May 2003.
[9] Yingwei Yao, and Georgios B. Giannakis, Blind carrier frequency o set estimation
in SISO,MIMO and multiuser OFDM systems," IEEE Trans.Signal Process.,
vol. 51, no,3 pp. 602-613,May 2003.
[10] Mingzheng Cao, and Hongya Ge, I/Q Imbalance Mitigation for STBC MIMOOFDM
Communication Systems," IEEE Trans.Acoustics, Speech and Signal Pro-
cessing, pp. 3093-3096,March 2008.
[11] Behzad Razavi, RF Microelectronics. Englewood Cli s, NJ: Prentice-Hall, 1998.
[12] Yuan-Pei Lin and See-May Phoong, BER minimized OFDM systems with channel
independent precoders," , volume 51, issue 9, pp. 2369-2380, September 2003.
[13] Li-Hsiang Lee, Performance Study of OFDM and SC-CP Systems in Nonideal
Transmission Environment," Master thesis, National Taiwan University, June
2005.
[14] Marcel J. M. Pelgrom, A. C. J. Duinmaijer, and A. P. G. Welbers, Matching
properties of MOS transistors," IEEE J. Solid-State Circuits, vol. 24, no. 5, pp.
1433-1439, October 1989.
[15] Leonardo Lanante Jr, Masayuki Kurosaki, and Hiroshi Ochi, Low Complexity
Compensation of Frequency Dependent I/Q Imbalance and CFO for Direct Conversion
Receivers," Circuits and Systems (ISCAS),June 2010.
[16] Siavash M. Alamouti, A simple transmit diversity technique for wireless communications,"
IEEE Transactions on Communications, vol. 16, pp. 1451-1458, Oct.
1998.
[17] Vahid Tarokh,Hamid Jafarkhani, and A. R. Calderbank, SpaceVTime Block
Codes from Orthogonal Designs," IEEE TRANSACTIONS ON INFORMATION
THEORY, vol. 45, no. 5, July. 1999.
[18] Lu Wu, Xian-Da Zhang, Pei-Sheng Li and Yong-Tao Su, A Closed-form Blind
CFO Estimator Based on Frequency Analysis for OFDM Systems," IEEE Trans-
actions on Wireless Communication, vol. 57, pp. 1634-1637, June 2009.
[19] Timo Roman,Samuli Visuri, Visa Koivunen, Blind Frequency Synchronization
in OFDM via Diagonality Criterion," IEEE Transactions on Signal Processing, vol.54, no. 8, August 2006.
[20] Qiuping Zhu, Weibing Wang and Yaxian Liu, A New Fast CFO Tracking Algorithm
for OFDM Systems," International Wiress Communications Networking
and Mobile Computing (WiCOM) Conf., pp.1-3,2010. 6th
[21] Lauri Anttila,Mikko Valkama, Circularity-Based I/Q Imbalance Compensation
in Wideband Direct-Conversion Receivers," IEEE Transactions on Vehicular Technology, vol. 57, no. 4, July 2008.