本論文提出一個以正交分頻多工(OFDM)為背景，結合多載波多天線非正交多重接取(NOMA)的下行系統，結合使用者分組的演算法與子載波配置迭代演算法，來有效的提升整體系統通道容量。在非正交多重接取系統的性質下，每個子載波能服務兩個或兩個以上的使用者來進行傳輸資料，進而提升系統效能，但在多天線架構下傳輸，同組使用者之間會因為同個頻帶傳輸而收到來自同一組使用者的干擾(Co-channel Interference)，也會收到來自其他天線的干擾(Inter-group Interference)，而這些干擾是非正交多重接取系統非常常見的，此論文採取 Zero-forcing Beamforming (ZFBF) 的方式來消除其他天線的干擾，同時採用Success Interference cancellation (SIC)消除來自傳輸功率大的使用者干擾。在NOMA系統中，通道增益大者我們視為強使用者(Strong User)，反之則稱為弱使用者(Weak User)，而我們將強使用者視為主要傳輸的使用者，會在本論文的限制中確保資料傳輸不會單獨發生在弱使用者身上。
在本篇論文中將會探討三個主要方向：一、各組中的使用者該如何挑選，才能將系統通道容量最大化。二、在進行子載波配置時，若同時傳送強使用者與弱使用者的通道容量高於單獨傳送強使用者，則會選擇以NOMA形式傳送，反之若單獨傳送強使用者的通道容量高於NOMA形式傳輸，則會以強使用者的形式進行傳輸，以迭代的方式來找出最大化通道容量。最後針對不同的使用者挑選，搭配上子載波配置來達到最佳的整體系統通道容量。
本論文所提出的非正交多重接取資源配置的設計，在模擬結果中，可看出隨機選取或隨機子載波配置與本論文的方法相比，有明顯的系統通道容量提升。

In this thesis, we propose user pairing, subcarrier allocation, and power control algorithms in Downlink beamforming multicarrier nonorthogonal multiple access (MC-NOMA) systems to maximize system capacity. In this system, every subcarrier can be assigned to two or more users for transmitting data. After executing the user pairing algorithm, every subcarrier is distributed to a cluster which includes groups of users for data delivery. Each group have two users, which are a strong user (SU) and a weak user (WU). If the NOMA transmission is not better than orthogonal multiple access (OMA), we guarantee all subcarriers are allocated to the SU in the system. The proposed method is composed of three parts. First, we propose a user pairing algorithm, then apply allocation designs and power control to maximize sum capacity. The simulation results illustrate that the proposed algorithm outperforms the OFDMA system.

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