OFDM系統(tǒng)中的同步技術(shù)研究

通信工程論文編號(hào):TX317  論文字?jǐn)?shù):14744,頁數(shù):31 
目錄

摘要 I
ABSTRACT II
第1章 引言 1
 1.1 背景 1
 1.2 研究內(nèi)容 2
第2章 OFDM系統(tǒng)模型及基本原理 3
 2.1 OFDM的系統(tǒng)模型 3
 2.2 OFDM系統(tǒng)的基本原理 4
 2.2.1 串并變換 4
 2.2.2 OFDM數(shù)字基帶調(diào)制 4
 2.2.3 循環(huán)前綴 4
 2.3 OFDM的優(yōu)缺點(diǎn) 6
 2.4 本章小結(jié) 6
第3章 正交頻分復(fù)用系統(tǒng)的同步問題 8
 3.1 OFDM系統(tǒng)中的同步概述 8
 3.2 OFDM系統(tǒng)中已有的同步算法概述 8
 3.2.1 基于循環(huán)前綴的同步算法 9
 3.2.2 基于訓(xùn)練符號(hào)的同步算法 9
 3.2.3 基于子載波的導(dǎo)頻 10
 3.3 同步的一般過程 10
 3.4 本章小結(jié) 11
第4章 定時(shí)同步 12
 4.1 引言 12
 4.2 OFDM符號(hào)定時(shí)對(duì)系統(tǒng)的影響 12
 4.3 OFDM符號(hào)定時(shí)算法分析 14
 4.3.1 Schmidl&Cox提出的算法分析 14
 4.3.2 Schmidl&Cox提出的算法應(yīng)用于16d系統(tǒng)性能分析 16
 4.4.3 分析一種新算法并仿真 19
 4.5 本章小結(jié) 22
第5章 載波頻率同步 23
 5.1 載波頻偏對(duì)OFDM系統(tǒng)的影響 23
 5.2 頻偏算法簡要分析 23
 5.3 本章小結(jié) 24
第6章 結(jié)束語 25
致謝 26
參考文獻(xiàn) 27

摘要
 
 正交頻分復(fù)用（OFDM）是一種多載波高效調(diào)制技術(shù)。由于能夠有效的對(duì)抗移動(dòng)環(huán)境中多徑信道引起的碼間干擾（ISI），近些年來受到越來越廣泛的關(guān)注。同步是一切數(shù)字通信系統(tǒng)能夠有效工作的基礎(chǔ)。由于OFDM相對(duì)于單載波通信系統(tǒng)對(duì)同步誤差更加敏感，因此一直作為OFDM領(lǐng)域研究的熱點(diǎn)。
 本文主要分析的是定時(shí)同步算法，也簡單闡述OFDM的基本原理﹑系統(tǒng)結(jié)構(gòu)和性能，并分析同步誤差對(duì)OFDM系統(tǒng)性能的影響。介紹了Schmidl和Cox提出的同步方案中的定時(shí)同步算法，在IEEE 802.16d系統(tǒng)中通過應(yīng)用并改進(jìn)此方法來實(shí)現(xiàn)定時(shí)同步，還分析了一種新的定時(shí)同步算法，并對(duì)其進(jìn)行仿真，仿真分析表明算法有較好的性能，具有很高的靈敏度，有一定實(shí)用價(jià)值。
 
關(guān)鍵詞 OFDM；IEEE802.16d；定時(shí)同步；訓(xùn)練符號(hào)
ABSTRACT
 
 Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technique with high performance. It becomes a hot problem in resent years because of its good ability against to Inter-Symbol Interference which is a common phenomenon in mobile transmission environment. Synchronization is a fundamental work to digital communications. Since OFDM systems are more sensitive to synchronization error compared to single-carrier communication systems, there are more and more attentions paid on it.
 Timing Synchronization algorithm is discussed in details in this thesis. The principles, schemes and performance of OFDM are also illustrated in this thesis. Besides, it also focuses on the effect, which is caused by synchronization error, to the performance of OFDM systems. Then the timing synchronization scheme proposed by Schmidl and Cox is analyzed. This scheme is also analyzed and improved in the system of IEEE 802.16d. A novel Timing Synchronization algorithm based on this scheme is discussed in details and realized in the system of IEEE 802.16d. The new algorithm simulation and mathematical analysis are presented in this thesis and the result shows that it is good in performance, sensitive and easy to realize.
 
 Key words: OFDM, IEEE802.16d, Timing Synchronization, Training Symbol