以非同調二元頻率偏移調變為基礎的正交分頻多工通訊系統在行動通訊衰減通道之研究分析

Abstract

在本篇論文中，我們將非同調二元頻率偏移調變(Noncoherent Binary Frequency-Shift Keying)作為正交分頻多工(Orthogonal Frequency Division Multiplexing)通訊系統的基礎調變，並探討此一架構在高速行動通訊衰減通道下的表現。 首先我們先探討非同調二元頻率偏移調變對於載波頻率偏移和相位失真干擾的抵抗能力，其次建立正交分頻多工通訊系統的數學模型，並整理其與非同調二元頻率偏移調變間的共通性－各子載波頻率正交。利用此一共通性，我們將兩者結合。接著，我們將前述系統利用瑞利衰減通道進行行動通訊衰減通道的效能分析，並與差動二元相位偏移調變做一比較，以印證本論文所提系統確實在高速行動通訊衰減通道下有較優異的表現。

In this thesis, we propose noncoherent binary frequency-shift keying for being the basic modulation in an OFDM communication system, and analyze the numerical result of bit-error-rate performances in high-speed mobile fading channel. First, we delve into NCBFSK, which is expected to have good immunity against not only carrier frequency offset, but also phase distortion. We continue to build the mathematical model to OFDM communication systems, and figure out that it shares a common attribute—carrier frequencies are orthogonal to each other. By taking the advantages of this similarity, we combine NCBFSK with OFDM communication system, which becomes our proposed system thereafter. We finally introduce Rayleigh fading channel as our mobile communication scenario, and compare our proposed system to a differential binary phase-shift keying based OFDM system. Our simulation result shows that the proposed system does have better performance in high-speed mobile fading channel.