具彩色雜訊之頻率選擇通道的ISI Free收發器設計

Abstract

多載波調變收發器已被廣泛的使用於頻率選擇通道上。在多載波的這個主題上，通道被很多個次通道所組成，每個通道的位元分配是根據每個次通道的訊雜比所分配。到目前為止，最廣被討論與使用的為以DFT為基礎的系統。然而在此種系統下每個次通道的頻帶區分並不理想，因此在文獻上就有人提出濾波器組的設計來改善頻帶區分。ISI 在這種設計方式是要被考慮的。在本篇論文裡，我們將設計FIR的收發器。我們共提出兩種設計方式，第一種方式是將頻帶做最大的分別，第二種方式是針對特定的雜訊來設計收發器。在我們的效能評估方面，我們發現第二種設計方式在相同方式的位元分配下比DFT為基礎的系統及第一種設計方式來的好。

The DMT(discrete multitone) transceivers have been shown to be a very useful technique for transmission over frequency selective channels. In the DMT scheme, the channel is divided into several subchannels. Bit are judiciously allocation according to the signal to noise ratio of each subchannels. So far, most of the DMT scheme are DFT based. In DFT based systems, the transmitting and receiving filters are DFT filters and have limited band separation property. For better frequency separation, filterbank transceiver has been proposed earlier in the literature. In these systems, the transceivers are obtained by interchanging the analysis and synthesis bank of perfect reconstruction filter banks. ISI is considered in the design phase. The performance is limited by the resulting ISI. In this thesis, we will design FIR filterbank transceivers that has zero ISI. Two types of designs will be considered. In type-I design, the transceivers are optimized for maximal based separation. In type-II design, transmission power is minimized for a given bit error rate and transmission rate. In this design, noise statistics is required and performance is superior to that of type-I design. Performance evaluation of both designs will be given.