新穎正交型單邊帶單載波調變應用於60GHz光載微波無線訊號系統

Abstract

隨著寬頻無線通訊需求持續的成長和要求更佳的網路服務品質,在 60-GHz 頻帶上有7-GHz免執照使用頻寬是一個不錯的選擇來達到千兆位元的資料傳輸率.光載微波信號系統被提出來,它利用光纖低損耗和幾乎無限的頻寬特性而可延伸收斂範圍來克服60-GHz 無線訊號在空氣中的高損耗.最近無線和光通訊上正交分頻多工調變已被廣泛的利用.比較傳統的雙邊帶單載波調變和正交分頻多工調變,正交分頻多工調變有過高的峰值功率比值,這將會對訊號產生非線性效應而降低訊號效能.在本篇論文裡我們提出單邊帶單載波調變並利用正交的維度搭載兩路正交的訊號.正交型單邊帶單載波調變比傳統的雙邊帶單載波調變有更高的頻譜使用效率而且比正交分頻多工調變有較低的峰值功率比值.然而,正交型單邊帶單載波調變會受到自我符元間干擾. 我們使用64-QAM單邊帶單載波調變實驗出42-Gb/s 光載微波無線訊號傳輸,頻譜使用效率6-b/s/Hz.在此使用決策型回授等化器和最大相似序列估計演算法被利用來補償經由光纖傳輸所產生的色散,自我符元間干擾.並探討不同匹配濾波器對此訊號在傳輸上的影響.在傳輸25公里單模光纖和3公尺的無線傳輸距離,此訊號的功率補償少於1dB.

As the demand of broadband wireless communication grows continually and better quality of network service has been required, the 60-GHz band that has 7-GHz unlicensed spectrum is a promising choice to offer multi-Gb/s data rate in wireless transmission. To overcome the high air loss of 60GHz wireless signals, radio-over-fiber (R-o-F) system have been proposed to extent the coverage due to low loss and almost unlimited bandwidth of optical fiber. Recently, orthogonal frequency-division multiplexing (OFDM) modulation has been widely utilized in both wireless and optical communication. Compared with double-sideband single-carrier (DSB-SC) modulation, OFDM signals have high peak-to-average-power ratio (PAPR) which will induce nonlinearly effect to degrade signal performance. In this paper, we propose SSB-SC modulation which utilizes two orthogonal dimensions to carry in-phase and quadrature-phase signals. Orthogonal SSB-SC modulation not only has higher spectral efficiency than conventional DSB-SC modulation but also has less PAPR than OFDM modulation. However, SSB-SC signals suffered from self-inter-symbol interferences. Record 42-Gb/s wireless signal transmission is experimentally demonstrated using a Radio-over-Fiber system employing the SSB-SC and 64-QAM, representing a spectral efficiency of 6-b/s/Hz. Decision feedback equalizer and Maximum likelihood sequence estimation were utilized to compensate for the signal distortion caused by fiber dispersion and self-inter-symbol interference. And we analysis that different match filter versus effects of SSB-SC signal transmission. After transmission over 25-km single mode fiber and 3 m wireless distance, the power penalty was less than 1dB.