動態解碼轉傳結合網路編碼之系統效能分析

The Performance Analysis Of Dynamic Decode and Forward Protocol With Cooperative Network Coding System

施雋桓(Chun-Huan Shih)

指導教授 ： 劉維正

國立中正大學/工學院/通訊工程學系/碩士(2012年)

摘要

合作式通訊 (cooperative communications) 是近年興起的無線通訊技術，在新一代無線通訊系統中有著重要地位，如作為4G (fourth-generation) 國際標準的增强型長期演進技術 (Long Term Evolution – Advanced, LTE– Advanced) 及全球互通微波存取 (Worldwide Interoperability for Microwave Access, WiMAX) 都有用到中繼站的原理。

網路編碼則是將來自多個傳送端的訊息用網路編碼技術加以結合後同時傳輸至下一個接收端，能有效提升系統吞吐量，提高傳輸效率。

本論文將建構一個使用動態解碼轉傳 (Dynamic Decode-and-Forward, DDF) 協定的單一中繼站合作式通訊系統結合網路編碼，研究在雷利、萊斯、仲上三種無線通道 (Rayleigh、Rician、Nakagami fading channel) 下中斷機率的情形，並分析系統的分集多工權衡，探討兩技術的結合對於系統效能上的改善。

經模擬與分析我們發現加入網路編碼的系統相較於一般動態解碼轉傳協定有較低的中斷機率、較高的分集增益，這也意味著系統的可靠度上升。但也由於在最後增加了一個階段來傳輸網路編碼的訊號，使得系統的多工增益較動態解碼轉傳略低。整體來說須按照需求選擇此系統的運用，若要求較高的可靠度而對於多工增益要求較低，便可使用網路編碼結合動態解碼轉傳協定之合作式通訊系統。

關鍵字

分集多工權衡 ； 中斷機率 ； 動態解碼轉傳 ； 網路編碼 ； 合作式通訊

並列摘要

Cooperative communications are emerging wireless communications techniques recently. It plays an important role in new generation of wireless communications. For instance, Long Term Evolution – Advanced (LTE– Advanced) and Worldwide Interoperability for Microwave Access (WiMAX) as international standard of fourth-generation, which the relaying technology applies to.

Network coding technology combines several messages at intermediate nodes and transmits the mixed message to destination nodes. Network coding could enhance throughput and improve transmission performance.

In this thesis, we consider a cooperative communications system using one relay dynamic Decode-and-Forward (DDF) protocol with network coding and one relay node. We research outage probability of this system under Rayleigh, Rician and Nakagami fading channels. Then we also analyze its diversity multiplexing tradeoff to test and verify system performance.

The simulation results show that our proposed system has lower outage probability and higher diversity gain than general DDF protocol. It means the improvement of the reliability of the system. However, we add a phase at the end to transmit the message coded by network coding, which results in the decrease of multiplexing gain. Overall, the application of this system depends on the requirement. We could choose this system if we need higher reliability.

並列關鍵字

Outage Probability ； Dynamic Decode and Forward ； Network Coding ； Cooperative Communications ； Diversity-Multiplexing Tradeoff

參考文獻

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