摘  要

CDMA技術是當前無線電通信，尤其是移動通信的主要技術，不論是在中國已經建立的IS-95規(guī)范的中國聯(lián)通CDMA網、各大移動通信運營商正準備實驗及建立第三代（3G）系統(tǒng)還是大設備研發(fā)商已經在開發(fā)的三代以后（也稱為4G）更寬帶寬的移動通信系統(tǒng)，CDMA都是主要的選擇。CDMA概念可以簡單地解釋為基于擴頻通信的調制和多址接入方案。其反向鏈路有接入信道和反向業(yè)務信道組成。接入信道用于短信令消息交換、能提供呼叫來源、尋呼響應、指令和注冊。
本設計選取CDMA通信系統(tǒng)中的接入信道部分進行仿真與分析。首先，通過學習相應的理論知識，熟悉接入信道實現(xiàn)的過程，對每一步的原理有了較深的理解，同時，也對MATALB軟件進行熟悉和了解，對MATLAB軟件中的SIMULINK部分及其內部的CDMA模塊用法和參數(shù)設置進行熟悉，然后運用MATLAB軟件對接入信道部分進行設計，并逐步地對各個模塊進行分析、仿真與驗證。目的是通過畢業(yè)設計工作熟悉現(xiàn)代無線通信系統(tǒng)的基本構成與基本工作原理，重點掌握卷積編碼、塊交織和碼擴展等相關編碼技術，并能將這些技術應用實際系統(tǒng)設計，提高自己對CDMA通信系統(tǒng)知識的認識。

關鍵字：CRC;卷積編碼;塊重復;交織;長碼;沃爾什;PN序列

Abstract

CDMA is the major technology used in the wireless communication , especially in the mobile communication. Following the IS-95 standard set up in China ,CDMA is the mostly choice whether in China Uninet net ,in the third system (3G) that all kinds of mobile businessmen are to build or in the wider system than the third one(named 4G)that the large equipments researching businessmen have been researching.The concept of CDMA may be interpreted as the simulation that base on frequency spreading and the multiply address access project.Its reverse channel is composed of access channel and traffic channel.The access channel is used for brief information exchanging 、providing the source about the calling、the call responding 、the instruction and the enrollment.
This design choose the part of connect channel to simulate and analyse. First,we can familiar with the process of connect channel ,understand the principleof every step of the procedure about thre channel,after studying the relating knowledge .At the same time ,we an also have some acquaintance with the software about MATLAB and the part of SIMULINK and how to set the parameter of every klock in the soft.Then we can use the MATLAB software to design the part of the connect channel, to analyse , to simulate and to validate the design of every block gradually. This purpose is to be familiar with the basic structure and basic principle of the morden wireless communication system, to mastery the technology about the Convolutional Encoder,Interleaver ,Coder spread and so forth, then use those technology to design system in practice,so that to improve our knowledge about the CDMA communication system.

Key words:CRC;Convolutional Enconder;Block Repeat;Interleaver;Long code;Walsh;
PN sequence

目   錄

中文摘要 關鍵字 …………………………………………………….……1
英文摘要 關鍵字 ………………………………………………….………2
目 錄  ……………………………………………………………….……...3
前 言  ………………………………………………………………..……..4
1  設計總體框架 ……………………………………………………..……5
2  設計各個部分原理知識介紹 ………………………………………..…6
2.1 卷積編碼……………………..………………………………………..…..7
2.2 交織技術介紹………………………..………….…………………………9
2.3 沃爾什函數(shù)說明………………………………..….………………………11
2.3.1 沃爾什函數(shù)特性說明………………………….…………………...……11
2.3.2 沃爾什函數(shù)的產生方法介紹……………………………………………..13
2.4 長碼的實現(xiàn)……………………………………………………………….15
2.6 PSK和OQPSK調制…………………………………………………………18
2.7 短碼的實現(xiàn)……………………………………………………….……….20
3  MTALAB軟件中的SIMULINK的簡介…………………………….………20
4  設計仿真、分析與驗證……………..………………………….……….22
4.1 設計總體模塊構造…………………………..…………………….……….22
4.2 對各個模塊進行分析與驗證 ………………………………….……………23
4.2.1 源中部分（subsystem1）設置、說明與分析……………………………...24
4.2.2 對卷積編碼器和重復模塊的設置、說明與分析  …………………………27
4.2.3 對子系統(tǒng)Subsystem2（塊交織器）模塊的設置、說明與分析 ……………30
4.2.4 沃爾什調制器輸出與長碼輸出及其異或驗證…..………………….………40
4.2.5 I路和Q路的輸出驗證與分析……………………………………………46
5.經驗總結…………………………………………………………………..49
謝  辭………………………………………………………………………..50
參考文獻……………………………………………………………………..51