現階段已有不少熱門的5G (Fifth Generation) 候選技術受到注意，而如何得到比使用在4G (Fourth Generation)中最主要技術正交分頻多工(Orthogonal Frequency Division Multiplexing; 簡稱OFDM) 擁有更大的頻譜效益是一項重要的議題。其中，濾波器组多載波 (Filter Bank Multicarrier；簡稱FBMC)便是一個很好的選擇，此系統解決了一些在OFDM系統所產生的一些問題，同時也同高了頻譜效益，而反離散傅立葉轉換(Inverse Discrete Fourier Transform；簡稱IDFT)與離散傅立葉轉換(Discrete Fourier Transform；簡稱DFT)演算法在這個系統之下已被發展了相當長的一段時間。由於在FBMC 系統下所傳輸的訊號皆為實數訊號，我們希望藉由利用只處理純實數運算的離散哈特萊轉換 (Discrete Hartley Transform；簡稱 DHT) 來取代離散傅立葉轉換之傳輸架構，進而降低FBMC調變/解調之運算複雜度來達到更好的傳輸品質。

Filter bank multicarrier (FBMC) transmission using offset quadrature amplitude modulation (OQAM) has received considerable attention for the fifth generation of wireless communication systems. For an FBMC/OQAM system with M subcarriers, two complex M-point inverse discrete Fourier transforms (IDFTs) for modulation along with two complex M-point DFTs for demodulation are required to transmit a sequence of complex M-point QAM data. In this thesis, we propose a FBMC transmission scheme based on the discrete Hartley transform (DHT) as an alternative to FBMC/OQAM to improve the system complexity and/or performance. For a DHT-based FBMC system with M subcarriers, the real part data of a frame of M-point complex QAM data are placed on all subcarriers on a one-by-one basis and each pair of subcarriers’ data with index reversal relationship are combined properly to form new data; the results are then transmitted with frequency diversity through the I-channel by one real M-point IDHT modulation followed by a synthesis filter bank similar to that used for FBMC/OQAM. Similar operations are necessarily performed at the same time for transmitting the corresponding imaginary data through the Q-channel. To recover the transmitted data from the I-channel and Q-channel, we can adopt an analysis filter bank, similar to that used for FBMC/OQAM, followed by real M-point DHT demodulation and appropriate data detection. Since the proposed DHT-based FBMC scheme uses the real DHT, instead of the complex IDFT/DFT, for both modulation and demodulation, it requires less computational complexity than FBMC/OQAM under the same data rate, although more complicated detection methods would be needed at the receiver. As demonstrated by simulation results, the proposed approach achieves close bit-error-rate performance to FBMC/OQAM for zero-forcing detection, but the performance is better if joint maximum-likelihood detection or joint minimum mean-squared error detection is employed to exploit the diversity gain of DHT transmission.

Contents
Absrtract i
Content iii
List of Figures iv
I. Introduction.........................................................................1
II. System Model .....................................................................4
III. The Proposed DHT-Based FBMC System............................7
A. Data Arrangement for I/Q Channel Transmission.................7
B. Orthogonality Condition......................................................11
C. Derivation of the Polyphase Structure................................14
D. Data Detection Methods.....................................................16
1) Joint zero-forcing detection...............................................18
2) Joint minimum mean-squared error (MMSE) detection......18
3) Joint maximum likelihood (ML)detection............................18
E. Complexity Comparison .....................................................19
IV. Simulation Results..............................................................21
V. Conclusion.........................................................................25
VI. References.........................................................................26

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