在本論文中，我們針對基於離散哈特利轉換(discrete Hartley transform；DHT)之濾波器组多載波 (filter bank multicarrier；簡稱FBMC)系統，提出時間同步與載波頻率偏移的訓練序列之設計與估測方法; 我們首先考慮於FBMC系統下同步的旁峰值效應，提升於單輸入單輸出 (single-input single-output, 簡稱SISO) 系統精細的時間同步(fine time synchronization)之表現。在多輸入多輸出(multiple-input multiple-output, 簡稱MIMO)系統中，我們推導出兩對頻域的訓練序列擺放於資料訊框中使得對應的時域訓練序列成為一個有加入循環字首(cyclic prefix)和循環字尾(cyclic postfix)的Zadoff-Chu序列，透過Zadoff-Chu序列的理想自相關特性，我們首先利用基於自相關(autocorrelation-based)的粗略的時間同步將載波頻率偏移除去後，再利用基於交相關(cross-correlation-based)的精細的時間同步找出每根天線之第一條通道路徑，最後我們透過多數決優化(Majority vote refinement)的演算法更進一步的提升MIMO系統中精細的時間同步之準確性; 另外，一針對較大系統載波頻率偏移估測的時域訓練序列設計也會在本論文中提出。電腦模擬結果顯示，所提出之SISO時間同步方法在ITU所規範的Pedestrian B與Vehicular B 通道模擬環境下可以分別達到0.8%以及1%的時間同步正確機率之提升; 所提出之MIMO時間同步方法在Pedestrian B與Vehicular B 通道模擬環境下均能達到99%的時間同步正確機率。

In this thesis, we propose new methods for time synchronization and carrier frequency offset (CFO) estimation in a filter bank multicarrier (FBMC) system based on the discrete Hartley transform (DHT). An improved fine time synchronization scheme is first proposed for single-input single-output (SISO) environments to improve the performance at very low signal-to-noise ratio (SNR) situations by considering the side-peak effect generated in a cross correlation–based synchronization process. Then, a new training sequence design is proposed for multiple-input multiple-output (MIMO) DHT-based FBMC systems, where two pairs of specific frequency-domain training sequences are placed successively among data frames to synthesize a time-domain Zadoff-Chu training sequence with appropriate cyclic prefix and postfix. Using this training sequence design, an autocorrelation-based scheme for coarse time synchronization/CFO estimation and a cross-correlation-based scheme for fine time synchronization are also developed for DHT-based MIMO FBMC systems. Furthermore, a majority vote refinement (MVR) of the timing estimates for different transmit-receive links is adopted to fully exploit the diversity in DHT-based MIMO FBMC systems to improve the synchronization performance. Finally, a training sequence arrangement is proposed for large CFO acquisition and time synchronization. Computer simulation results show that the proposed SISO synchronization approach achieves nearly a 0.8% and 1% improvement on correct time synchronization at very low SNR situations under the ITU Vehicular B and Pedestrian B channel models, respectively. It is also demonstrated that the proposed MIMO synchronization approach is able to attain 99% of correct time synchronization for both of the ITU channels.¬

Abstract i
Contents ii
List of Figures iii
List of Tables v
I. Introduction 1
II. DHT-Based FBMC with Two Prototype Filters 4
III. An Existing Fine Time Synchronization Scheme for DHT-Based SISO FBMC 7
A. A Vector Representation of DHT-Based FBMC Symbols 7
B. A SISO Time-Domain Training Sequence Structure 11
C. Fine Time Synchronization 12
IV. An Improved Fine Time Synchronization Scheme for DHT-Based SISO FBMC 16
A. Coarse Time Synchronization and CFO estimation 16
B. Fine Time Synchronization 17
C. A Novel Peak Detection Criterion 18
V. New Synchronization Schemes for DHT-Based MIMO FBMC 20
A. A MIMO Time-Domain Training Sequence Structure 20
B. MIMO Synchronization Sequence Design 22
C. MIMO Coarse Time Synchronization and CFO estimation 25
D. MIMO Fine Time Synchronization 27
E. A Training Sequence Arrangement for Large CFO Acquisition 31
VI. Simulation Results 33
VII. Conclusion 46
Appendixes 47
A. A Novel Filter Design for DHT-Based FBMC 47
B. A Derivation of the Variance Shown in (45) 51
C. A Derivation of the Optimal Threshold Shown in (48) 52
References 53

[1] Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Amend. 4: Enhancements for Very High Throughput for Operation in Bands Below 6 GHz, IEEE Standard P802.11ac/D6.0, Jul. 2013.
[2] P. Siohan, C. Siclet, and N. Lacaille, “Analysis and design of OFDM/OQAM systems based on filterbank theory,” IEEE Trans. Signal Process., vol. 50, no. 5, pp. 1170–1183, May 2002.
[3] A. Viholaninen, M. Bellanger, and M. Huchard, “PHYDYAS-Physical layer for dynamic access and cognitive radio,” Tech. Rep. D5.1, EU FP7-ICT Future Networks, Jan. 2009. Project website: http://www.ict-phydyas.org/.
[4] B. Farhang-Boroujeny, “OFDM versus filter bank multicarrier,” IEEE Signal Process. Mag., vol. 28, no. 3, pp. 92–112, May 2011.
[5] R. N. Bracewell, “Discrete Hartley transform,” J. Opt. Soc. Amer., vol. 73, no. 12, pp. 1832–1835, Dec. 1983.
[6] R. N. Bracewell, “The fast Hartley transform,” Proc. IEEE, vol. 72, no. 8, pp. 1010–1018, Aug. 1984.
[7] K. Jones, The Regularized Fast Hartley Transform. Dordrecht, The Netherlands: Springer, 2010.
[8] C.-T. Tuan, “A filter bank multicarrier transmission system based on the discrete Hartley transform,” M.S. thesis, Inst. Commun. Eng., National Tsing Hua Univ., Hsinchu, Taiwan, Aug. 2016.
[9] M. Bellanger et al., “FBMC physical layer: A primer,” PHYDYAS, Tech. Rep., Jun. 2010.
[10] H.-S. Pan, “A filter bank multicarrier system based on the discrete Hartley transform and two prototype filters,” M.S. thesis, Inst. Commun. Eng., National Tsing Hua Univ., Hsinchu, Taiwan, Dec. 2017.
[11] Y. H. Yun, C. Kim, K. Kim, Z. Ho, B. Lee, and J.-Y. Seol, “A new waveform enabling enhanced QAM-FBMC systems,” in Proc. IEEE Int. Workshop Signal Process. Adv. Wireless Commun. (SPAWC), Stockholm, Sweden, Jun./Jul. 2015, pp. 116–120.
[12] H. Nam, M. Choi, S. Han, C. Kim, S. Choi, and D. Hong, “A new filter-bank multicarrier system with two prototype filters for QAM symbols transmission and reception,” IEEE Trans. Wireless Commun., vol. 15, no. 9, pp. 5998–6009, Sep. 2016.
[13] C. Kim, Y. H. Yun, K. Kim, and J. Y. Seol, “Introduction to QAM-FBMC: From waveform optimization to system design,” IEEE Commun. Mag., vol. 54, no. 11, pp. 66–73, Nov. 2016.
[14] S. Mirabbasi and K. Martin, “Overlapped complex-modulated transmultiplexer filters with simplified design and superior stopbands,” IEEE Trans. Circuits Syst. II, vol. 50, no. 8, pp. 456–469, Jul. 2003.
[15] W. Chung et al., “Synchronization error in QAM-based FBMC system,” in Proc. IEEE Military Commun. Conf. (MILCOM), Baltimore, Maryland, USA, Oct. 2014, pp. 699–705.
[16] T. Fusco, A. Petrella, and M. Tanda, “Data-aided symbol timing and CFO synchronization for filter bank multicarrier systems,” IEEE Trans. Wireless Commun., vol. 8, no. 5, pp. 2705–2715, May 2009.
[17] W. Chung, C. Kim, S. Choi, and D. Hong, “Synchronization sequence design for FBMC/OQAM systems,” IEEE Trans. Wireless Commun., vol. 15, no. 10, pp. 7199–7211, Oct. 2016.
[18] T. Fusco and M. Tanda, “Blind frequency-offset estimation for OFDM/OQAM systems,” IEEE Trans. Signal Process., vol. 55, no. 5, pp. 1828–1838, May 2007.
[19] M. Hua, M. Wang, K. Yang, and K. Zou, “Analysis of the frequency offset effect on Zadoff-Chu sequence timing performance,” IEEE Trans. Commun., vol. 62, no. 11, pp. 4024–4039, Nov. 2014.
[20] C.-L. Wang and H.-C. Wang, “On joint fine time adjustment and channel estimation for OFDM systems,” IEEE Trans. Wireless Commun., vol. 8, no. 10, pp. 4940–4944, Oct. 2009.
[21] Guidelines for Evaluations of Radio Transmission Technologies for IMT-2000, ITU-R M.1225, 1997.
[22] C.-H. Chou, “Time synchonization for a filter bank multicarrier system based on the discrete Hartley transform and two prototype filters,” M.S. thesis, Inst. Commun. Eng., National Tsing Hua Univ., Hsinchu, Taiwan, Dec. 2017.