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研究生： 陳政雨
Chen, Cheng-Yu
論文名稱： 適應性重傳機制下之合作式通訊
Cooperative Communications with Adaptive Regeneration Relay
指導教授： 張名先
Chang, Ming-Xian
學位類別： 碩士
Master
系所名稱： 電機資訊學院 - 電腦與通信工程研究所
Institute of Computer & Communication Engineering
論文出版年： 2011
畢業學年度： 99
語文別： 英文
論文頁數： 46
中文關鍵詞： 合作式多樣性 、正交分頻多工 、LDPC碼 、低複雜度結合法 、網格編碼
外文關鍵詞： cooperative diversity, OFDM, LDPC code, low complexity combining method, network coding
相關次數： 點閱：212  下載：2 
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    • 近年來,合作式通訊已受到許多關注。在合作式通訊上，它的多樣性能使多用戶環境中裝備一根天線的移動節點去分享它們的天線來構成一個虛擬的多天線的傳送器並達成空間上的多樣性。
    在這邊論文裡，我們發展了一套以正交分頻多工調變技術為基礎且結合網格編碼技術的合作式通訊架構。在傳送者與中繼站的配合中,我們採用解碼-重傳的轉傳方式。而對於此種轉傳方式有許多解調方法被提出，我們在這裡除了模擬合作式-MRC方法並從此延伸出適應性編碼後傳之中繼站解碼(LAR)[2],經過模擬結果,可發現LAR比合作式-MRC更能適應通道變化因為它可以調整中繼站的傳輸功率以適應通道。
    最後在多個用戶多個中繼的情況下，我們結合LDPC碼的特性並套用兩種解調方法，我們發現利用LAR解碼的合作式系統更能有效地利用通道訊息以達到空間之多樣性。

    In recent years, cooperative communications has received much attention. The diversity in the cooperative communications enables mobiles equipped with a single antenna to share their antennas in a multi-user environment, and with the virtual multiple-antenna transmitter spatial diversity is provided.
    In this thesis, we study a set of cooperative communication combined with network coding based on the orthogonal frequency division multiplexing modulation technique. In the coordination among sender and relay nodes, we adopt decode-and-forward as (DF) as our relaying method. Many detection schemes have been proposed for the DF. In addition to simulating cooperative-MRC method, we also consider the adaptive-link regenerative relay strategies (LAR) [2]. By the simulation results, we find that LAR is adaptive to channel varying better than C-MRC because of scaling the symbol power at relay.
    Finally, in the case of multi-user multi-relay condition, we combine the characteristic of LDPC code and apply two kinds of demodulation methods. We find that the cooperative system with LAR is more efficient in using channel information to achieve space diversity.

    Contents Chinese Abstract I English Abstract II Acknowledgements III Contents IV List of Figures VI 1 Introduction 1 2 System Model 3 2.1 Introduction to OFDM 3 2.2 Introduction to OFDM/TDMA 6 2.3 Fading channel 7 2.3.1 Multipath Model 7 3 Introduction to Cooperative Diversity 9 3.1 System Model 9 3.2 Cooperative Relaying Method 11 3.3 Cooperative Maximum Ratio Combining 12 3.4 Link-adaptive regeneration strategies 14 4 Network Coding Based Cooperative Scheme 16 4.1 Introduction to Network Coding 16 4.2 Cooperative Network Coding 17 4.2.1 Network Coding in Physical Layer 17 4.2.2 System Model 19 4.2.3 LAR with network coding system at relay node 20 4.3 Decoding Algorithm 21 4.3.1 Maximum Ratio Combining 21 4.3.2 C-MRC in Non-Perfect Inter-User Channel 22 4.3.3 LAR in Non-Perfect Inter-User Channel 23 4.4 Cooperative Network Coding with Multi-Relay System 24 4.5 Simulation Results 25 5 Multi-User Multi-Relay Cooperative Scheme with block code 29 5.1 Cooperative Code with Block Code 29 5.2 Cooperative Code with LDPC Code 32 5.2.1 Introduction to LDPC Code 32 5.2.2 Tanner Graph 33 5.2.3 C-MRC Decoding with LDPC Code 35 5.2.4 LAR Decoding with LDPC Code 36 5.3 Selection Decode to LDPC Code 36 5.4 LAR System in the Case of Feedback Errors 38 5.5 Simulation Results 38 6 Conclusion 44 Bibliography 45 List of Figures 2.1 The bandwidth efficiency between conventional FDM and OFDM 3 2.2 The block diagram of the OFDM transceiver 4 2.3 A guard interval example with delay spread=2 5 2.4 A single OFDM/TDMA frame 6 3.1 Two basic user cooperation scheme 10 4.1 A simple network coding example 16 4.2 The basic cooperative network coding scheme 19 4.3 Cooperative network coding with C-MRC 26 4.4 Cooperative network coding with LAR 26 4.5 Comparison between C-MRC and LAR in 2-1 scheme 27 4.6 Cooperative multi-relay network coding system with C-MRC 27 4.7 Cooperative multi-relay network coding system with LAR 28 5.1 (6,3) block code and (7,4) block code 29 5.2 Tanner graph for (10, 5) code 34 5.3 The example of length-4 cycle of Tanner graph 35 5.4 Comparison between (6,3) and (7,4) block code with C-MRC 39 5.5 Comparison between (6,3) and (7,4) block code with LAR 39 5.6 Cooperative LDPC code with C-MRC 40 5.7 Cooperative LDPC code with LAR 40 5.8 Comparison between C-MRC and LAR in cooperative LDPC code 41 5.9 Selection decode with C-MRC (7,3) code 41 5.10 Selection decode with C-MRC (5,2) code 42 5.11 Comparison between C-MRC and LAR in selection decode 42 5.12 Performance comparison between instant CSI and outdated CSI in LAR system 43

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