基于OFDM信号的新型∑△调制器研究

针对OFDM系统的量化噪声问题，研究适于多载波信号的新型量化噪声整形器.比较单零点∑△与多零点∑△调制器的适用性，进而给出多零点∑△调制器用于OFDM系统的完整方法、理论及仿真分析.研究表明，无过采样多零点∑△调制器可有效减小OFDM系统的量化噪声，具有比传统单零点∑△更好的整形性能.3bit量化、信噪比6dB时，系统误比特率性能改善3个数量级；但受限于非循环的量化噪声结构，多零点∑△调制器未能达到完全消除量化噪声的理想状态.

A Novel Sigma-Delta Modulator Based on OFDM Signals

To solve the problem of quantization noise in OFDM systems,a study on a novel quantization noise shaper for multi-cartier signal is presented.The paper first compares the applicability of two kinds of sigma-delta modulators with the single zero and multiple zeros.Then it gives the complete scheme,theory and simulation analysis of the multi-zero sigma delta modulator for OFDM systems.Studies show that the multi-zero sigma delta modulator without oversampling can effectively reduce the quantization noise in OFDM systems,and performs better in noise shaping.Under the conditions of 3bit quantization and 6dB SNR,the bit error rate of the system deceases by 3 order of magnitude.But limited by the non-cyclic quantization noise structure,the proposed modulator cannot achieve the ideal state of eliminating the quantization noise completely.