在單載波頻域等化系統中, 循環字首的使用可以避免區塊間干擾及符元間干擾, 並使得在傳送訊號與無線環境通道的效應從線性摺積轉換成迴旋摺積, 進而降低接收端頻域等化器的運算複雜度。然而, 使用循環字首會降低頻寬的使用效益; 為了增加系統的頻寬使用效益, 在這篇論文裡我們將針對不使用循環字首的單載波頻域等化系統進行研究。當使用相同的頻域等化器卻不使用循環字首時會造成區塊間干擾及符元間干擾,並造成解調變的錯誤率提高; 過去有許多研究探討過如何提高此系統的效能, 遺憾的是其複雜度都過高以至於難以實現。為了降低運算複雜度並提高頻寬效益, 本論文提出了一種新穎的低複雜度前置循環字首重建技術。在這個技術中我們使用了循序干擾消除的概念以及QR 分解去降低所需要的複雜度, 此外, 我們還利用了在相異取樣點上干擾大小不同的特性去提升系統效能。我們更進一步分析提出的前置循環字首重建技術的運算複雜度並和之前相關研究做比較, 證實本論文提出的方法能有效的降低重建前置循環字首所需要的運算複雜度。

The cyclic prefix (CP) is usually adopted in single carrier frequency domain equalization (SC-FDE) system to avoid inter-block interference (IBI) and inter-symbol interference (ISI) in multipath fading channels. In addition, the use of CP also converts the linear convolution between the transmitted signal and the channel into a circular convolution, leading to significant decrease in receiver equalization.
However, the use of CP reduces the bandwidth efficiency. Therefore the SC-FDE system without CP is investigated in this thesis. A number of schemes have been proposed to improve the performance of systems without CP, where both IBI and ICI are dramatically increased. Unfortunately, most of the existing schemes have extremely high computational complexity and are difficult to realize. In this thesis, a novel low-complexity CP reconstruction (CPR) scheme is proposed for interference cancellation, where the successive interference cancellation (SIC) and QR decomposition (QRD) are adopted. In addition, the system performance is further improved by using the fact that the
interferences of different symbols are not the same. Simulation experiments are conducted to verify the system performance of the proposed scheme. It is shown that the proposed scheme can effectively reduce the interference, while maintain a low computational complexity.

1 Introduction 1
2 System Model 4
2.1 SC-FDE System with Sufficient CP . . . . . . . . . . . . . . . . . . 4
2.2 SC-FDE System without CP . . . . . . . . . . . . . . . . . . . . . 8
3 Cyclic Prefix Reconstruction Schemes on SC-FDE System 11
3.1 Linear Minimum Mean Square Error Equalizer . . . . . . . . . . . . 11
3.2 RISIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 Maximum Likelihood Detection . . . . . . . . . . . . . . . . . . . . 14
4 Proposed Cyclic Prefix Reconstruction with Successive Interference
Cancellation 17
4.1 Successive Interference Cancellation . . . . . . . . . . . . . . . . . . 17
4.2 Detection Rule Based on Log-Likelihood Ratio . . . . . . . . . . . . 19
4.3 Modified SIC with QR Decomposition . . . . . . . . . . . . . . . . 21
4.4 Computational Complexity Analysis . . . . . . . . . . . . . . . . . 23
5 Simulation 25
6 Conclusion 33
References 34
Abbreviations 39

[1] Part 16: Air Interface for fixed broadband wireless access systems, IEEE Standard
802.16-2004, 2004.
[2] Physical channels and modulation (release 8), 3GPP TSG PAN TS 36.211
V8.7.0, May 2009.
[3] S. B. Weinstein and P. M. Ebert, “Data transmission by frequency-division
multiplexing using the discrete Fourier transform,” IEEE Trans. Commun.,
vol 19, no. 5, pp 628–634, Oct. 1971.
[4] 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.
[5] H. Sari, G. Karam, and I. Jeanclaude, “Transmission techniques for digital
terrestrial TV broadcasting,” IEEE Commun. Mag., vol. 33, no. 2, pp. 100–
109, Feb. 1995.
[6] J. Choi, C. Lee, H. W. Jung, and Y.H. Lee, “Carrier frequency offset compensation
for uplink of OFDM-FDMA systems,” IEEE Commun. Lett., vol.
4, no. 12, pp. 414–416, Dec. 2000.
[7] D. Huang and K. B. Letaief, “An interference-cancellation scheme for carrier
frequency offsets correction in OFDMA systems,” IEEE Trans. Commun.,
vol. 53, no. 7, pp. 1155–1165, Jul. 2005.
[8] M. S. El-Tanany, Y. Wu, and L. Hazy, “OFDM uplink for interactive broadband
wireless: analysis and simulation in the presence of carrier, clock and
time error,” IEEE Trans. Broadcast., vol. 47, no. 1, pp. 3–19, Mar. 2001.
[9] T. Jiang and Y. Wu, “An overview: peak-to-average power ratio reduction
techniques for OFDM signals,” IEEE Trans. Broadcast., vol. 54, no. 2, pp.
257–268, Jun. 2008.
[10] S. H. Han and J. H. Lee, “An overview of peak-to-average power ratio reduction
techniques for multicarrier transmission,” IEEE Trans. Commun., vol
12, no. 2, pp. 56–65, Apr. 2005.
[11] G. T. Zhou and L. Peng, “Optimality condition for selected mapping in
OFDM,” IEEE Trans. Signal Process., vol. 54, no. 8, pp. 3159–3165, Aug.
2006.
[12] D. Falconer, S. L. Ariyavistakul, A. Benyamin-Seeyar, and B. Eidson, “Frequency
domain equalization for single-carrier broadband wireless systems,”
IEEE Commun. Mag., vol. 40, no. 4, pp. 58–66, Apr. 2002.
[13] F. Pancaldi, G. M. Vitetta, R. Kalbasi, N. Al-Dhahir, M. Uysal, and H.
Mheidat, “Single-carrier frequency domain equalization,” IEEE Signal Process.
Mag., vol. 25, no. 5, pp. 37–56, Sep. 2008.
[14] A. Gusmao, R. Dinis, and N. Esteves, “On frequency domain equalization and
diversity combining for broadband wireless communications,” IEEE Trans.
Commun., vol. 51, no. 7, pp 1029–1033, Jul. 2003.
[15] F. Pancaldi and G. M. Vitetta, “Block channel equalization in the frequencydomain,”
IEEE Trans. Commun., vol. 53, no. 3, pp. 469–471, Mar. 2005.
[16] A. Tajer and A. Nosratina, “Diversity order in ISI channels with single-carrier
frequency domain equalizers,” IEEE Trans. Wireless Commun., vol. 9, no. 3,
Mar. 2010.
[17] A. V. Oppenheim, R. W. Schafer, and J. R. Buck, Discrete-time signal processing,
2nd ed., Prentice Hall, 1999, ch. 8.
[18] K. Dukhyun and G. L. Stuber, “Residual ISI cancellation for OFDM with
applications to HDTV broadcasting,” IEEE J. Sel. Areas Commun., vol. 16,
no. 8, pp. 1590–1599, Oct. 1998.
[19] N. A.-Dhahir and J. M. Cioffi, “Efficiently computed reduced-parameter
input-aided MMSE equalizers for ML detection: a unified approach,” IEEE
Trans. Inf. Theory, vol. 42, no. 3, pp. 903–914, May 1996.
[20] N. A.-Dhahir and J. M. Cioffi, “Optimum finite-length equalization for multicarrier
transceivers,” IEEE Trans. Commun., vol. 44, no. 1, pp. 56–64, Jan.
1996.
[21] B. F.-Boroujeny and D. Ming, “Design methods for time domain equalizers
in DMT transceivers,” IEEE Trans. Commun., vol. 49, no. 3, pp. 554–562,
Mar. 2001.
[22] “Orthogonal frequency division multiplexing,” U.S. Patent No. 3, 488, 4555,
filed Nov. 14, 1966, issued Jan. 6, 1970.
[23] W. Henkel and T. Kessler, “Maximizing the channel capacity of multicarrier
transmission by suitable adaptation of the time domain equalizer,” IEEE
Trans. Commun., vol. 48, no. 12, pp. 2000–2004, Dec. 2000.
[24] Y. Li and T. Hwang, “Iterative cyclic prefix reconstruction for coded singlecarrier
systems with frequency domain equalization (SC-FDE),” in Proc. 57th
Veh. Technol. Conf., Jeju, Korea, Apr. 2003, vol. 3, pp. 1841–1845.
[25] C.-J. Park and G.-H. Im, “Efficient cyclic prefix reconstruction for coded
OFDM systems,” IEEE Commun. Lett., vol. 8, no. 5, pp. 274–276, May 2004.
[26] H.-C. Won and G.-H. Im, “Iterative cyclic prefix reconstruction and channel
estimation for a STBC OFDM system,” IEEE Commun. Lett., vol. 9, no. 4,
pp. 307–309, Apr. 2005.
[27] T. Hwang and T. Li, “A bandwidth efficient block transmission with frequency
domain equalization,” in Proc. 6th Circuits and Systems Symposium
on Emerging Technologies: Frontiers of Mobile and Wireless Communications,
Shanghai, China, May 2004, vol. 3, pp. 1841–1845.
[28] K. Hayashi and H. Sakai, “Interference cancellation schemes for single-carrier
block transmission with insufficient cyclic prefix,” EURASIP Journal on
Wireless Communications and Networking, vol. 2008, Article ID 130747, 12
pages, 2008. doi:10.1155/2008/130747
[29] I. Martoyo, T. Weiss, and F. Capar, “Low complexity CDMA downlink receiver
based on frequency domain equalization,” in Proc. 58th Veh. Technol.
Conf., Orlando, USA, Oct. 2003, vol. 2, pp. 987–991.
[30] Steven M. Kay, Fundamentals of statistical signal processing, volume I: estimation
theory. Prentice Hall PTR, 1998.
[31] John G. Proakis, Digital Communications, 4th ed. McGraw-Hill, 2000, ch. 4.
[32] G. H. Golub and C. F. Van Loan, Matrix Computations. Johns-Hopkins University
Press, 1996, ch. 5.
[33] M. Noh, Y. Lee, and H. Park, “Low complexity LMMSE channel estimation
for OFDM,” in IEE Proceedings Communications, vol. 153, no. 5, pp. 645–
650, Oct. 2006.
[34] Part 11 : Wireless LAN medium access control (MAC) and physical layer
(PHY) specifications : high-speed physical layer in the 5 GHz Band, IEEE
Standard 802.11a-1999, 1999.