正交多頻分工技術之I/Q不平衡補償於60GHz光載微波無線訊號系統

Abstract

隨著科技的發展，對於高速的無線傳輸的要求也越來越急迫，因此，為了要提高傳輸速度，我將載波頻率提高到擁有7G免授權頻段(57-64)的60GHZ。但由於60GHZ的微波訊號在空氣中有非常嚴重的衰減，因此我們使用了光載微波無線訊號來解決這個問題，然而，60GHz 無線網路在實作上仍然存在一些問題需要改善，首先就是由於不存在兩個元件是擁有相同頻率響應，這個問題導致系統的品質下降，特別是在7G的頻寬下更是嚴重。因此，為了得到更好的訊號品質，補償I/Q不平衡是無法避免的。 在這篇論文中，我使用一個頻域上的適應性等化器來補償I/Q不平衡對OFDM訊號的影響，我們成功的傳輸60GHz 頻段上7 GHz免授權頻寬的32GB/S OFDM訊號，在經過25公里的單模光纖和3公尺的無線傳輸以後，訊號品質幾乎沒有改變。

As the development in technology and science, the requirements of multi-Gbps wireless transmission are more important. For increasing data transmission, we raise the carrier frequency to 60 GHz which can offers 7 GHz unlicensed band (57-64 GHz) according to Federal Communications Commission (FCC). However, because of the serious propagation loss of 60-GHz RF signal, the radio-over-fiber (RoF) system is proposed to reduce the overall cost of 60 GHz wireless access network. To receive the higher performance in 60 GHz RoF system, compensating I/Q imbalance is inevitable especially in 7 GHz band because there are not two components which have identical frequency response in practice. In this thesis, an adaptive equalizer in frequency domain is applied to compensate the influence of I/Q imbalance on OFDM signal. We successfully demonstrate a 32 Gb/s OFDM signal on 3m wireless distance at 60 GHz within 7-GHz license-free band. Transmission over 25-km standard single-mode fiber and 3m wireless distance were achieved with negligible penalty.