單載波及多載波區塊展頻系統之信號處理: 干擾抑制與多樣接收

Signal Processing for Single-Carrier and Multi-Carrier Block Spread Spectrum Systems: Interference Suppression and Diversity Receiver

廖述旻(Shu-Min Liao)

指導教授 ： 鄧俊宏

元智大學/電機通訊學院/通訊工程學系/博士(2013年)

https://doi.org/10.6838/YZU.2013.00205

摘要

近年來，蜂巢式無線通訊服務已從傳統的語音傳輸轉變為以數據傳輸為主流，對於無線網路實體層所要求的資料傳輸率與頻寬效益也相對不斷提高。因此在本論文中，吾人主要探討兩大類高效率展頻系統上行鏈路收發機設計: 一是多載波分碼多重進接系統之強健干擾抑制接收機設計，另一則為多載波展頻系統與單載波分頻多工存取應用之收發機設計。
在第一部份，為克服多重進接干擾、載波頻率偏移及多路徑衰減通道環境問題，吾人提出了一種新型模糊最小輸出能量接收機，並應用於多載波分碼多重進接系統。此接收機主要將上鏈多載波分碼多重進接系統模型，以指向向量的方式表現，針對接收訊號所合成載波頻率偏移及多路徑通道衰減之指向向量，以模糊最小輸出能量方法抑制多重進接干擾，此方法可有效解決指向向量不準的問題。接著，使用的信號子空間投影技術及最大比例結合準則可進一步提升系統性能。此外，吾人將單一輸入單一輸出多載波分碼多重進接系統結構延伸至多重輸入多重輸出及空時區塊碼之多載波分碼多重進接系統結構。模擬結果中顯示，此多載波分碼多重進接系統設計可有效地抑制載波頻率偏移及多重進接干擾的影響，並且優於傳統的接收機。
在第二部分中，我們專注於高速環境、高資料率、低峰均功率比之上鏈收發器設計。因此，在多載波展頻系統方面，吾人考慮了頻率位移正交鍵及循環位移正交鍵調變方法，並結合Chu序列的使用降低發射訊號之低峰均功率比，進一步，吾人提出差分式收發機設計，在不需估計通道的情況下，可以克服多路徑衰減通道效果，也有效對抗頻率偏移的問題。上述技術分別應用於多載波展頻系統與單載波分頻多工存取系統收發機設計中。由模擬結果得知，吾人所提出的高效率收發機設計，可獲得M階增益及通道分集增益。在具有低峰均功率比及強健性能特色下，吾人所提出的系統可應用於未來低耗能的綠色通訊環境中。

關鍵字

多載波分碼多重進接 ； 單載波分頻多工存取 ； 多載波展頻系統 ； 強健式多重進接干擾消除 ； 差分式收發機 ； 最大比例結合 ； 最大似然偵測 ； 多用戶 ； 多資料串 ； 載波頻率偏移

並列摘要

In recent years, cellular communication services, ranging from traditional voice traffic to data transmission, the data rate, and bandwidth efficiency of the wireless-network physical layer have improved. In this dissertation, efficient receivers are designed for two prime spread spectrum (SS) systems: (1) robust interference suppression receivers design for uplink multicarrier code division multiple access (MC-CDMA) system, and (2) multicarrier spread spectrum (MC-SS) and single-carrier frequency division multiple access (SC-FDMA) transceivers design.
In part I, in order to efficiently suppress multiple access interference (MAI) under carrier frequency offset (CFO) and multipath fading environment, we proposed a novel robust minimum output energy (MOE) detector for MC-CDMA systems. We rewrite the received signal as a model of steering vector for MC-CDMA system. Then, the robust CFO constrained MOE detector can suppress MAI and combat the problem of steering vector mismatch. Next, using the signal subspace projection technique and maximum ratio combining (MRC) criterion can improve the system performance. Furthermore, we extended the single input single output (SISO) MC-CDMA structure to multiple input multiple output (MIMO) and MIMO space-time block coding (STBC) MC-CDMA structures. Simulation results confirm that the proposed MC-CDMA systems have sufficient robustness to suppress CFO and MAI effects and that it outperforms conventional detectors.
In part II, we focus on high-mobility, high data rate and low peak-to-average-power ratio (PAPR) for uplink transceiver design. Thus, for multi-carrier spread spectrum (MC-SS) systems, we consider frequency shift orthogonal keying (FSOK) and cyclic shift orthogonal keying (CSOK) methods. Then, the Chu sequence is adapted to transmit signal design with a low PAPR. Furthermore, we develop the differential transceiver design, which not only overcome the multipath fading channel effect without requiring channel estimation., but also effective against the problem of CFO. The techniques can be applied to MCSS and SC-FDMA systems design. The simulation results confirm that the proposed efficient transceivers acquire the M-ary and frequency diversity gain. Moreover, the proposed systems can be applied for the green communication system with low power consumption and robust performance in the future.

並列關鍵字

MC-CDMA ； SC-FDMA ； MC-SS ； robust MAI suppression ； differential transceiver ； MRC ； ML detection ； Multiuser ； Multi-stream ； CFO

參考文獻

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