IQ失衡補償和VBLAST補償技術應用於 2 × 2多天線輸入多天線輸出60GHz極化多工暨正交分頻多工光載微波訊號系統

Abstract

隨著手持式行動裝置的普及和無線通訊技術的蓬勃發展，使得人們對於現今多媒體影音傳輸與互動式多媒體應用需求量增加，高容量無線傳輸服務的需求也日益增加，並且由於無線通訊網路其有著可移動性且涵蓋範圍廣泛等優點，用戶在使用此類網路服務時不再受到區域性的束縛，無線網路服務已漸漸成為生活中不可會或缺的一部分。然而，隨著影音互動裝置與多媒體設備的更新導致無線資料傳輸需求量持續增加，無線通訊系統也必須隨之發展出更新穎的技術。為了追求更高的傳輸效益，往更高頻率尋找能利用的頻寬，並提高資料傳輸速率已是必然的趨勢。 在57 ~ 64 GHz間的7 GHz免認證連續頻帶擁有高頻寬，但是60 GHz訊號在無限空間傳輸中衰減率極高。近年來，結合光纖通訊與60GHz無線通訊系統概念被提出，同時為了提高頻譜效益，使用多天線輸入多天線輸出技術。 傳統的極化多工系統有功率衰減的問題，許多研究提出了不同的系統或方法解決，但是需要極化追蹤器或兩倍的保護區間，使系統複雜度增加或頻譜效益降低。本文提出載波錯頻極化多工傳輸系統，不但解決功率衰減的問題而且不需要額外的元件或保護區間，在60 GHz光載無線訊號系統的基礎上，再與2 × 2多天線輸入及多天線輸出無線系統作結合，同時處理多輸入多輸出光訊號及無線訊號。然而在60 GHz光載微波訊號系統研究中發現許多需克服的系統問題，例如I/Q不平衡效應和60GHz無線通道及元件的不平整頻譜響應，以數位訊號處理技術改善系統，包括I/Q不平衡補償技術、位元存取技術和垂直分層空間時間碼補償技術。

Due to the rapid development of wireless and mobile communications, demands for higher date rate coupled with advent of popular bandwidth-need applications such as high-definition video, 3D TV and interactive multimedia are putting pressure on wireless communication systems to offer higher data rate. The license-free V-band (57-64 GHz) can provide considerably more bandwidth. However, V-band wireless transmission is limited by high propagation loss in air. The need to remedy this situation led to the development of Radio-over-Fiber (RoF) technology, combining the advantages of fiber and wireless network. Moreover, multi-input multi-output (MIMO) technology can improve spectral efficiency by transmitting multiple signals within the same bandwidth using spatial multiplexing. There is a power decade issue in traditional polarization multiplexing division (Polmux) system. Several schemes have been proposed to solve this issue by adding polarization tracking or double guard band. This thesis proposed a frequency offset 60-GHz Polmux-OFDM-RoF system to solve power decade issue without additional components and guard band. And then, the proposed system combines with 2x2 MIMO wireless system. Deal with MIMO optical signals and wireless signals at the same time. In order to solve the impairments from IQ imbalance and uneven frequency response caused by 60-GHz wireless channel and component, this thesis employs digital signal processing technologies including of bit-loading algorithm, I/Q imbalance compensation and VBLAST compensation.