本論文針對完美和非完美的通道狀態信息情境，探討一個包含K個用戶與N個子載波之下行多載波多輸入多輸出非正交多重接取(MIMO-NOMA)系統的資源分配問題。首先，我們根據用戶配對、子載波配置以及各子載波上的用戶功率分配形成一個資源分配最佳化問題，以在所有用戶皆具有相同位元錯誤率(BER)效能的限制條件下，最小化系統的BER。接著，我們針對此一資源分配問題提出一個以迭代方式運作的次佳解，其中每一迭代過程包含二個部分：1)將當前具有最高BER和第二高BER的二個用戶配對起來，以及2)針對該二用戶，執行聯合子載波配置和功率分配，以在所配置之子載波上進行NOMA傳輸並最小化平均BER；上述迭代過程將持續進行，直到沒有子載波可供配置為止。另外，我們提出一個Q函數近似作法，簡化現有的BER公式，並據以對每一子載波推導出一個具有低複雜度的閉合式NOMA功率分配解。對於一個M*M 的MIMO-NOMA系統，所提出之資源分配演算法具O(N2M3 K2) 的時間複雜度，因此在實際應用上確實可行；廣泛的電腦模擬結果顯示，基於Q函數近似之功率分配方法可逼近理論效能，這也使得所提出的資源分配演算法可在不同情境下達到優異的BER效能。

This thesis investigates the resource allocation issues for a downlink multicarrier multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) system with K users and N subcarriers under both perfect and imperfect channel state information scenarios. A resource allocation optimization problem is first formulated in terms of user pairing, subcarrier assignment, and users’ power allocation on each subcarrier to minimize the bit error rate (BER) of the system under a constraint that all the users have identical BER performance. Then, a suboptimal solution of the resource allocation problem is proposed that iteratively performs two parts of operations: 1) pairing the two users with the highest and second highest BERs at the current iteration; 2) conducting joint subcarrier assignment and power allocation for the paired two users in order to minimize the average BER of NOMA transmission on the assigned subcarrier. The above iterative procedure continues until there are no subcarriers available for assignment. Moreover, an approximation of the Q function is made to simplify existing BER expressions for deriving a low-complexity closed-form NOMA power allocation solution for each subcarrier. For an M*M MIMO-NOMA system, the proposed resource allocation scheme involves time complexity of O(N2M3 K2), which is definitely feasible for practical applications. Extensive computer simulation results demonstrate that the power allocation method based on the approximated Q-function approaches the theoretical performance very well and enables the resource allocation scheme to achieve excellent BER performance for various scenarios.

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