A Cooperative Scheme using Iterative Decoding with BCM-Improved Inter-user Links

合作通訊已經被提出來對抗衰減通道造成的影響，在合作通訊中，每個使用在合作的過程中不僅傳送自己的資訊,也傳送其他使用者的資訊。為了高頻寬效率，我們提出一個使用 M ary 的區塊編碼調變的合作方式。一個使用者的編碼器將自己的資訊框和其他使用者的資訊框裡用區塊編調變的方式結合在一起。藉著適當的延遲操作，每個使用者可以更正確的解碼其他使用者的資訊。在接收端，我們使用遞迴式的解碼。在解碼過程中，上一刻封包解碼出的事後機率將會被用來當作此時封包的事前機率。分析與模擬顯我們所提出的方式會有較好的表現尤其是在糟糕的內部使用者連結的條件之。後，我們將提出的方式應用在另一個實用且有趣的合作方式來達成更有效間與時間上的多樣性。Cooperative communication, in which each user in the cooperative process transmits not only its own information but also information of another user, has been proposed to combat the deleterious effects of fading channels. We present a coded cooperative scheme using M-ary modulation for high bandwidth efficiency. Each user’s encoder combines its own information frame and another user’s information frame by using block coded modulation (BCM). With a proper delay operation, each user could decode another user’s information more correctly. Iterative decoding is used at the destination receiver which means the a posteriori probability of the decoding packet last time is used as the a priori probability for decoding the current packet. The analyses and simulations show that our proposed scheme achieves better performance especially under worse inter-user links condition. At last, we apply the proposed scheme to achieve the spatial-time diversity for another practically interesting cooperative scenario.Contentsbstract iist of Tables viist of Figures v INTRODUCTION 1 THE OVERVIEW OF WIRELESS COOPERATIVE COMMUNI-ATION 4.1 Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Cooperative Communication System . . . . . . . . . . . . . . . . . . 6.3 Cooperative Signaling Method . . . . . . . . . . . . . . . . . . . . . . 7 THE PERFORMANCE ANALYSIS OF CONVENTIONAL CODEDOOPERATION 17.1 Pairwise Error Probability Analysis . . . . . . . . . . . . . . . . . . . 17.2 Cooperative Case Probabilities Analysis . . . . . . . . . . . . . . . . 20.3 End-to-End Error Analysis . . . . . . . . . . . . . . . . . . . . . . . . 23 THE PROPOSED SCHEME 26.1 BCM Arrangement 8PSK-based for Inter-user link . . . . . . . . . . . 27.1.1 Encoding Process . . . . . . . . . . . . . . . . . . . . . . . . . 27.1.2 Decoding Process . . . . . . . . . . . . . . . . . . . . . . . . . 30.1.3 Theoretic Coding Gain Analysis and Numerical Result . . . . 33.2 BCM Arrangement 16QAM-based for Inter-user link . . . . . . . . . 42.2.1 Encoding Process . . . . . . . . . . . . . . . . . . . . . . . . . 42.2.2 Decoding Process . . . . . . . . . . . . . . . . . . . . . . . . . 43.2.3 Theoretic Coding Gain Analysis and Numerical Result . . . . 44.3 The Proposed Scheme For Another Scenario . . . . . . . . . . . . . . 46.3.1 System Description . . . . . . . . . . . . . . . . . . . . . . . . 46.3.2 Numerical Result . . . . . . . . . . . . . . . . . . . . . . . . . 49 CONCLUSION 51ibliography 5