訊號強度調變/直接偵測之通道在有符號間干擾下的單載波頻域補償法

Abstract

在這個論文當中，我們分析了在無線光通訊系統上有符號間干擾（ISI）與高斯白雜訊（AWGN）的單載波調變頻域補償法。單載波調變頻域補償法是一個補償方法相當類似正交分頻多工（OFDM）的補償方式。然而，單載波頻域補償法比起正交分頻多工系統，更適合使用在訊號強度調變/直接偵測（IM/DD）之通道上。因為單載波頻域補償法使用在訊號強度調變/直接偵測之通道上不需要灌注一個很強的直流訊號。隨著傳輸速率的加快，符號間干擾會主宰了我們系統效能。在這個論文當中我們結合了脈衝位置調變法（PPM）與單載波頻域補償法來對抗在訊號強度調變/直接偵測之通道符號間干擾。這樣的系統同時有著在脈衝位置調變法上很好的平均功率效益與單載波頻域補償法低系統複雜度的優點。同時，我們分析了單載波頻域調變法的位元錯誤率也比較了幾個已知的補償方法。

In this thesis, we examine single carrier modulation with frequency domain equalization (SC-FDE) for optical communication systems using intensity modulation with direct detection (IM/DD) in the presence of additive white Gaussian noise. SC-FDE is a technique whose processing is quite similar to that of OFDM. Unlike OFDM, however, SC-FDE is compatible with IM/DD channels because it does not require the transmission of a strong dc. For an IM/DD channel, at high data rate regime, the effect of intersymbol interference (ISI) starts to dominate system performance. Inthis paper, we examine the use of SC-FDE and pulse position modulation (PPM) to combat ISI for IM/DD channels. Such a system enjoys the average power efficiency of PPM and the low complexity equalization of SC-FDE. We analyze the bit error performance of SC-FDE and compare it with a few known techniques.