隨著下一代無線通信系統對各種即時多媒體業務需求的增加和網路技術的迅速發展，寬頻無線通信已成為無線通信技術發展的必然趨勢。IEEE802.16a標準對於實理層的關鍵技術中建議了正交分頻多工(OFDM)和採用頻域等化技術的單載波傳輸 (SC/FDE)兩種方案。同時，這兩種技術方案也是第四代移動通信的核心技術。正交分頻多工（Orthogonal Frequency Division Multiplexing，OFDM）是一種多載波調製技術。它具有頻譜效率高、抗多徑干擾能力強、等化簡單等突出優點。它的主要缺點主要是對頻率同步比較敏感，並且峰值平均功率比（PAPR）過高。單載波頻域等化（Single Carrier- Frequency Domain Equalization，SC-FDE）技術不同於傳統的單載波傳輸技術。SC-FDE採用分組傳輸，並且在頻域等化。
OFDM和SC-FDE技術既有相同點，又有相異處。本文分別介紹了MC-CDMA和SC-FDE-CDMA系統的基本原理，並且比較了它們的異同。
本文的內容包括三個方面。第一部分是針對幾種常見的OFDM-CDMA技術方案進行了比較，然後提出了Jakes瑞利通道下的MC-CDMA系統模型，並給出了最小均方誤差（MMSE）準則下的等化係數運算式和等化－解展頻合併處理下的系統接收模型。第二部分是針對SC-FDE-CDMA系統模型，並對等化和解展頻分開/合併處理時系統性能進行了推導。第三部分是系統模擬，對兩種技術進行了模擬和結果的比較分析。

With the increasing requirements of next generation wireless communication system for all kinds of real- time multimedia service and the rapid development of the internet, broadband wireless communication has become a full potential in the development of wireless communication. OFDM (Orthogonal Frequency Division Multiplexing) and SC-FDE (Single Carrier Transmission with Frequency Domain Equalization) was proposed to be the key physical technologies in IEEE 802.16a standard. Meanwhile, these two schemes belong to the key technologies of the forth Generation mobile communication. OFDM is a kind of multi-carrier modulation technology with outstanding benefits of high frequency efficiency, strong anti-multi-path interfere ability, easiness for equalization, etc. Its main defects lie on its sensitivity to frequency synchronization and high PAPR (Peak Average Power Rate). SC-FDE is not the same as the traditional single carrier transmitting technologies. SC-FDE transmits in groups and equalizes in frequency domain.
OFDM and SC-FDE technologies have similarities as well as different points. We described the basic principle of MC-CDMA and SC-FDE systems and also made a comparison to them in the paper.
The contents include the following three parts. The first one includes the second and the third chapter, we made a comparison to the several common OFDM-CDMA technologies, then proposed MC-CDMA system model in Jakes-Raleigh channel and gave the equalizer coefficient expression in MMSE rule and the system reception module for equalization-dispreading combing. The second part is the fourth chapter, in which we gave the system module of SC-FDE-CDMA system and deduced the performance for equalization-dispreading combing or dividing. The third part is chapter five, we set a system simulation environment in matlab and made a simulation and analysis for the two technologies.

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