偏移正交振幅調變濾波器組多載波（Filter Bank Multicarrier with Offset Quadrature Amplitude Modulation；簡稱FBMC/OQAM）系統為一種多載波調變技術，其被認為是正交分頻多工（Orthogonal Frequency Division Multiplexing；簡稱OFDM）以外的另一種選擇。然而在此系統下，各載波之間的正交性不同於OFDM存在於複數域，FBMC/OQAM其正交性反而只存在於實數域，這導致以往所使用在OFDM上的通道估測方法無法直接使用在FBMC/OQAM系統中，也代表著FBMC/OQAM系統中符元會受到虛數值的固有干擾。在此篇論文中，我們提出了一種在FBMC/OQAM系統中的新穎通道估測前置序列設計，這種前置序列結構是由多個前置序列單位（Preamble Unit；簡稱PU）所組成，而一個PU則是在時間－頻率方格中由三乘三的矩陣所組成的單位。每個PU可由中心為”1”，上下左右和四個角落由純虛數“j”或“-j”適當排列所組成，將中心所估測到的通道達到最小均方誤差，相反的，每個PU可由中心為“j”，周圍由純實數“1”或“-1”以同樣方式所組成。此論文所提出之前置序列設計是由實數與虛數之干擾近似方法（Interference Approximation Method with real or imaginary symbols；簡稱E-IAM-C），其設計方式並未考慮四個角落來最小化均方誤差。另一方面，PU中心以外位置的通道資訊可以經由線性內插法所求得。最後，經過理論分析和模擬結果顯示，此篇論文所提出之新穎前置序列結構在計算均方誤差、位元錯誤率和複雜度上，都達到比E-IAM-C較好的表現。

Filter bank multicarrier (FBMC) modulation using offset quadrature amplitude modulation (OQAM) is a type of multicarrier modulation (MCM) that can be considered as an alternative to orthogonal frequency-division multiplexing (OFDM). However, the conventional channel estimation methods for OFDM cannot be directly used to FBMC/OQAM. This is due to the fact that the orthogonality among subcarriers only holds in the real field for FBMC/OQAM, rather than in the complex field as OFDM. In other words, the real-valued data of FBMC/OQAM would suffer intrinsic interference from the imaginary-valued data. In this thesis, we propose a new preamble design for channel estimation in FBMC/OQAM systems. The proposed preamble structure is formed by duplicating a preamble unit (PU) defined as a 3×3 symbol matrix in a time-frequency lattice. The center element of the PU could be a real symbol “1” surrounded appropriately by imaginary symbols “j” and “–j” for the upper-side, lower-side, left-side, right-side, and 4 corner elements such that the mean-squared error (MSE) of channel estimation is minimized for the center subcarrier. The center element could also be an imaginary symbol “j” with surrounding symbols set as “1” or “–1” in a similar way to minimize the MSE. The proposed preamble design can be regarded as an improved version of the extended interference approximation method with real or imaginary symbols (E-IAM-C) which does not consider the 4 corner elements for MSE minimization. With the estimated channel gains of all center subcarriers, we can calculate the remaining subcarrier’s channel gains simply by linear interpolation. Theoretical analysis and simulation results show that the proposed preamble design for channel estimation outperforms E-IAM-C in terms of the MSE, bit error rate, and computational complexity.

ABSTRACT i
CONTENTS ii
LIST OF FIGURES iii
LIST OF TABLES iv
I. INTRODUCTION 1
II. SYSTEM MODEL 5
III. A PREAMBLE-BASED CHANNEL ESTIMATION SCHEME FOR FBMC/OQAM SYSTEMS 7
A. Channel Estimation Using Preamble Pilots 7
B. Design of Preamble Pilots for MSE-Based Channel Estimation 8
C. A Preamble Structure for Channel Estimation 10
D. Analysis of the MSE Performance for Different Channel Estimation Schemes 10
IV. SIMULATION RESULTS 14
V. CONCLUSION 20
REFERENCES 21

[1] J. A. C. Bingham, “Multicarrier modulation for data transmission: an idea whose time has come,” IEEE Commun. Mag., vol. 28, no. 5, pp. 5-14, May 1990.
[2] B. Le Floch, M. Alard, and C. Berrou, “Coded orthogonal frequency division multiplex [TV broadcasting],” Proc. IEEE, vol. 83, no. 6, pp. 982-996, Jun. 1995.
[3] S. Weinstein and P. Ebert, “Data transmission by frequency division multiplexing using the discrete Fourier transform,” IEEE Trans. Commun., vol. 19, pp. 628-634, Oct. 1971.
[4] H. Boelcskei, “Orthogonal frequency division multiplexing based on offset QAM,” Advances in Gabor Analysis, Boston, MA, USA: Birkhäuser, 2003, Ch. 12, pp. 321-352.
[5] H. Boelcskei, P. Duhamel, and R. Hleiss, “Design of pulse shaping OFDM/OQAM systems for high data-rate transmission over wireless channels,” in Proc. IEEE Int. Conf. Commun. (ICC), Vancouver, BC, Canada, Jun. 1999, pp. 559-564.
[6] K. W. Martin, “Small side-lobe filter design for multitone data-communication applications,” IEEE Trans. Circuits Syst. - II: Analog Digit. Signal Process., vol. 45, no. 8, pp. 1155-1161, Aug. 1998.
[7] P. Siohan, C. Siclet, and N. Lacaille, “Analysis and design of OQAM-OFDM systems based on filterbank theory,” IEEE Trans. Signal Process., vol. 50, no. 5, pp. 1170-1183, May 2002.
[8] B. Farhang-Boroujeny, “OFDM versus filter bank multicarrier,” IEEE Signal Process. Mag., vol. 28, no. 3, pp. 92-112, May 2011.
[9] B. Farhang-Boroujeny, “Filter bank multicarrier modulation: a waveform candidate for 5G and beyond,” Advances in Electrical Engineering [Online], 2014: 482805, 25 pages, DOI: 10.1155/2014/482805.
[10] B. Farhang-Boroujeny and C. H. Yuen., “Cosine modulated and offset QAM filter bank multicarrier techniques: A continuous-time prospect,” EURASIP J. Adv. Signal Processing [Online], 2010: 165654, 16 pages, DOI: 10.1155/2010/165654.
[11] J. Proakis and M. Salehi, Digital Communications, 5th ed. New York, NY, USA: McGraw-Hill, 2007.
[12] “PHYDYAS–Physical layer for dynamic access and cognitive radio,” Project website: http//www.ict-phydyas.org/.
[13] J. Du and S. Signell, “Time Frequency localization of pulse shaping filter in OFDM/OQAM systems,” in Proc. Int. Conf. Inf., Commun. Signal Process., Dec. 2007, pp. 1-5.
[14] G. Cherubini, E. Eleftheriou, and S. Olcer, “Filtered multitone modulation for very high-speed digital subscriber lines,” IEEE J. Sel. Areas Commun., vol. 20, no. 5, pp. 1016-1028, Jun. 2002.
[15] F. Schaich and T. Wild, “Waveform contenders for 5G; OFDM vs. FBMC vs. UFMC,” in Proc. Int. Symp. Commun. Control Signal Process., Athens, Greece, May 2014, pp. 457-460.
[16] C. Lélé, J.-P. Javaudin, R. Legouable, A. Skrzypczak, and P. Siohan, “Channel estimation methods for preamble-based OFDM/OQAM modulations,” in Proc. European Wireless Conf., Paris, France, Apr. 2007, pp. 59-64.
[17] J. Du, and S. Signell, “Novel preamble-based channel estimation for OFDM/OQAM systems,” in Proc. IEEE Int. Conf. Commun. (ICC), Dresden, Germany, Jun. 2009.
[18] E. Kofidis and D. Katselis, “Improved interference approximation method for preamble-based channel estimation in FBMC/OQAM,” in Proc. European Signal Process. Conf. (EUSIPCO), Barcelona, Spain, Aug. 2011, pp. 1603-1607.
[19] D. Kong, D. Qu and T. Jiang, “Time domain channel estimation for OQAM-OFDM systems: algorithms and performance bounds,” IEEE Trans. Signal Process., vol. 62, no. 2, pp. 322-330, Jan. 2014.
[20] J. P. Javaudin, D. Lacroix, and A. Rouxel, “Pilot-aided channel estimation for OFDM/OQAM,” in Proc. IEEE Veh. Technol. Conf. - Spring (VTC-Spring), Apr. 2003, pp. 1581-1585.
[21] X. He, Z. Zhao, and H. Zhang, “A pilot-aided channel estimation method for FBMC/OQAM communications system,” in Proc. Int. Symp. Commun. Info. Technol., Gold Coast, Queensland, Australia, 2012, pp. 175-180.
[22] T. Yoon, S. Im, S. Hwang, and H. Choi, “Pilot structure for high data rate in OFDM/OQAM-IOTA system,” in Proc. IEEE Veh. Technol. Conf. - Fall (VTC-Fall), Calgary, Alberta, Canada, Sep. 2008.
[23] T. H. Stitz, T. Ihalainen, A. Viholainen, and M. Renfors, “Pilot-based synchronization and equalization in filter bank multicarrier communications,” EURASIP J. Adv. Signal Process. [Online], 2010: 741429, 18 pages, DOI: 10.1155/2010/741429.
[24] W. Cui, D. Qu, T. Jiang, and B. Farhang-Boroujeny, “Coded auxiliary pilots for channel estimation in FBMC-OQAM systems,” IEEE Trans. Veh. Technol., vol. 65, no. 5, pp. 2936-2946, May 2016.