有效率頻寬分配的離散式多載波收發器

Abstract

離散式多載波收發器被運用在高速的資料傳輸, 例如非對稱數位用戶迴路 (Asymmetric Digital Subscriber Line, 簡稱 ADSL)的傳輸。現今大部份實現的多載波收發器是離散式傅立葉轉換(Discrete Fourier Transform, 簡稱DFT)為基礎的離散式多載波收發器。此種收發器的冗數 (redundancy)通常與頻道的秩 (order)相同。在此篇論文, 我們提出了減少冗數的最佳化離散式多載波收發器, 此種收發器在固定的出錯率以及傳輸速率下, 所需的傳輸能量最小。並且我們還會導出以離散式餘弦轉換為基礎的離散式多載波收發器。我們將會比較這三種系統。從我們的實驗結果可以得知, 減少冗數的最佳化離散式多載波收發器所須要的傳輸能量最小並且可以增進頻寬使用的效率。

The discrete multitone transceivers have been applied to high speed data transmission, such as ADSL (Asymmetric Digital Subscriber Line). Most of DMT systems that have studied and implemented are DFT based. The number of redundancies in DFT based DMT system are usually equal to the order of channel. In this thesis, optimal DMT transceiver with reduced redundancy that minimize the transmission power for a given bit error rate and transmission bit rate will be derived. We will also derive the DCT based DMT system. The comparison of these three system will be performed. From simulation, we will conclude the optimal DMT system with reduced redundancy require less transmission power and improve the bandwidth efficiency. 1.1 Outline 1.1 Notations 3 Ch.2 DMT System Model 7 2.1 Loops Characteristics and Channel Modeling 7 2.2 System Model 8 2.3 Polyphase Representation 9 Ch. 3 ISI Free Systems 16 3.1 DFT based DMT System 16 3.2 Generalized DMT Systems 17 3.3 Minimum redundancy Transceivers 18 3.4 DCT based DMT system 20 Ch. 4 The Optimal DMT Transceiver 21 4.1 Optimal Bit Allocation 21 4.2 Design of the Optimal Transceiver 21 4.3 Theoretical power ratio of optimal DMT system and DCT based DMT system 25 4.4 DFT based DMT bit allocation 25 Ch. 5 System Simulation 28 5.1 Channel Equalization 28 5.2 Nonnegative Integer Bit Allocation 31 5.3 Complexity 32 5.4 Design Example 33 Ch. 6 Performance Evaluation 42 6.1 Simulation Result 42 6.2 Discussion 45 Ch. 7 Conclusion 62 [參考文獻]