Design of Lagrange-Vandermonde Transceivers for Multicarrier Systems

• Main Authors: Yao-Nien Tsai, 蔡曜年
• Other Authors: See-May Phoong
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/36986428975728860258

碩士 === 國立臺灣大學 === 電信工程學研究所 === 92 === Transmultiplexers have been known in digital communication for many years. Historically the transmultiplexer has been viewed as a system that converts from time multiplexed components of a signal to a frequency multiplexed version, and back. The mathematical theory of transmultiplexer however allows more general interpretations and, therefore, applications. Some of these include channel equalization, channel identification and so forth. The role of transmultiplexers in digital communications has gained new importance because of many recent results in filter bank precoders. A new class of codes, named Lagrange-Vandermonde(LV) codes, was proposed to achieve complete multiuser interference (MUI) suppression without estimating the channel. The proposed system selects user codes at the transmitter so that MUI is eliminated, irrespective of the channel zero locations and frequency-selective fading is converted to flat fading. DFT-based Discrete Multi Tone (DMT) and Orthogonal Frequency Division Multiplex (OFDM), applied in many applications e.g. digital audio broadcasting (DAB) ,digital terrestrial broadcasting (DVB-T) and asymmetrical digital subscriber line (ADSL), are special cases of LV system. A dual transceiver design called VL (Vandermonde -Lagrange), with the precoder-decoder roles interchanged, is derived in order to add system flexibility in the code assignment procedure. In this thesis, we use some nonlinear programmings to optimize user code for different objective functions. We compare the performance of LV/VL transceivers with DMT/OFDM systems. Simulations demonstrated the system’s superior performance in multiuser communications.