以頻域為基礎利用超取樣之時域等化器設計

Abstract

我們以頻域為基礎來設計應用於高速數位用戶迴路的時域等化器。在高速數位用戶迴路的應用中，通常會分為上傳與下載兩個不同頻帶的傳輸。我們利用降低在沒有使用頻帶上的干擾雜訊來設計時域等化器。這種設計方法可以直接的控制時域等化器的零點是它落在沒有使用的頻帶上，已提升傳送訊號的傳輸率。進而，我們提高系統接收端的取樣頻率來增加設計上的自由度和傳輸率。模擬的結果顯示，我們提出的設計方法不僅可以有效的縮短通道的等效長度也可以大大的提升系統的傳輸速率。

In this paper, we design TEQ (time domain equalizer) for DSL (digital subscriber loops) applications using a frequency domain based approach. In DSL applications, usually frequency division multiplexing is used to separate the upstream and downstream signals. In either direction of transmission, some of the frequency bands are not used for transmission. Interference is formulated and minimized in the frequency domain to take advantage of the unused frequency bands. The frequency domain approach allows us to have a more direct control over the frequency response of the resulting TEQ, which is crucial in the final achievable transmission bit rates. Furthermore we will extend the method to the case when there is oversampling at the receiver to gain additional performance improvement. Oversampling is often used for time synchronization at the receiver and it also arises when the number of tones actually used for transmission is less the maximum possible number. The simulation examples demonstrate that the proposed methods (with or without oversampling) shortens the channel effectively and very good transmission bit rates can be achieved.