臺灣博碩士論文加值系統

單載波區塊傳輸系統往往不適用於高速率無線傳輸，因為在快速時變通道中，單載波區塊傳輸需要使用高複雜度的等化器來解決符號間干擾的問題。 但在使用預編碼正交分頻多工系統的前提下，我們可以使用頻域等化器來實現單載波區塊傳輸系統。然而，正如同正交分頻多工系統，子頻帶間干擾將影響效能，即使提高訊雜比仍不能改善位元錯誤率。
在此論文中，我們引進現有的子頻帶間干擾消除演算法，根據單載波區塊傳輸的特徵，將之修改並引入單載波區塊傳輸系統，所提出的演算法亦能增加頻域符元數來消除子頻帶間干擾，此演算法亦提供傳輸率與效能之間的權衡。然而，不像正交分頻多工系統在頻域傳輸訊號，單載波區塊傳輸系統是在時域傳輸訊號。因此，我們需要解決殘餘子頻帶間干擾的問題，所以我們在等化器的部分加入了殘餘子頻帶間干擾的變異數，論文最後模擬結果證明我們成功克服了這個殘餘子頻帶間干擾所產生曲線上翹的問題。

Traditional Single-Carrier (SC) transmission may be not suitable for a high rate wireless transmission, because it requires high-complexity equalization for frequency-selective channels to remove the inter-symbol interference. But under the pre-coded OFDM architecture, we can achieve SC block transmission with frequency-domain (FD) equalization. However, just like the OFDM system, there exists interference among subchannels for fast time-varying channels. Due to this inter-subchannel interference (ICI), we cannot reduce the bit-error rate (BER) by increasing the signal-to-noise ratio (SNR).
In the thesis, we first consider an ICI self-reduction algorithm for the OFDM system. Based on the characteristics of SC system, we modify the algorithm and apply it on the system of SC block transmission. The proposed algorithm is able to add the diversity of FD symbols to make the ICI self-reduced. This algorithm also provides a trade-off between ICI reduction and system throughput. However, unlike the OFDM system in which the transmitted symbols are in the frequency domain, the transmitted symbols in the SC system are in the time domain. Therefore, we need to handle the problem of residual ICI. After the ICI self-reduction, the equalization needs to estimate the variance of the residual ICI. By adding the variance of residual ICI to the variance of white noise in the equalization process, we can improve the performance. The simulation verifies the performance of our method.

中文摘要.................................................I
Abstract................................................II
Acknowledge............................................III
Contents................................................IV
List of Figures ........................................VI
Chapter 1. Introduction .................................1
Chapter 2. Single-Carrier Frequency-Domain Equalization .3
2.1 SC-FDE Systems.....................................3
2.1.1 Linear Precoded OFDM Systems.....................3
2.1.2 SC-FDE Systems...................................7
2.2 Channel Model......................................9
2.2.1 Modification of Jakes' Rayleigh Fading Model.....9
2.2.2 Time-Variant Channel of Jakes’ Model............12
2.3 Channel Estimation..............................15
2.3.1 Least-Square Fitting Approach (LSF).............15
2.3.2 Least-Squares fitting – Channel Impulse Response (LSF-CIR)...18
2.4 Frequency-domain Equalization.....................21
2.5 The simulation for channel estimation...............23
Chapter 3. An Efficient Algorithm of ICI self-Cancellation...27
3.1 An Efficient ICI Self-Reduction Algorithm ........28
3.1.1 The Transmitter.................................28
3.1.2 The Receiver....................................29
3.1.3 The Low-Complexity Equivalent Receiver..........31
3.2 Simulation for the Proposed Algorithm.............33
3.3 Modified Frequency-domain Equalization..............35
3.3.1. The Effect of Residual ICI.......................36
3.3.2 The ICI-Reduction Algorithm.......................36
3.3.3 Simulation for ICI-Reduction Algorithm............40
3.4 Compare with Different ICI Self-Cancellation Algorithms...42
3.4.1 The Algorithm for SC-FDE system.................42
3.4.2 Simulation Results..............................44
Chapter 4. Conclusion...................................47
Bibliography............................................48

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