在本論文中，我們考慮包含一個基地台和K個使用者群組的下行巨量多輸入多輸出非正交多重接取(MIMO-NOMA)系統，其中每一群組由兩個使用者組成，並提出一迭代式聯合功率分配、預編碼和解碼技術，以適用於非完美通道估測情境。在給定通道估測值和通道估測誤差資訊的情況下，我們首先利用區塊對角化技術設計K個群組預編碼器以消除群組間的干擾；這些群組預編碼器可將一個K群組MIMO-NOMA通道分解為K個平行的單群組MIMO-NOMA通道，也因此原先的多群組設計問題可簡化成單群組設計問題。針對單一群組，使用者功率分配因子可藉由最小化最大的解碼訊息均方誤差求得，對應的解碼器可透過最小化解碼訊息均方誤差來設計，而對應的預編碼器則可在基地台功率限制情況下進行設計，以最小化系統中所有使用者的解碼訊息均方誤差總和；所設計的功率分配因子、預編碼器和解碼器可採迭代方式進行更新，直至收斂。電腦模擬結果顯示，相較於未考慮通道估測誤差資訊的相關設計方式，所提出的聯合設計技術可大幅改善系統的位元錯誤率，其中功率分配的效益會隨著群組內之兩個使用者間的通道增益差增大而更加顯著。

In this thesis, a downlink massive multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) system is considered that consists of a base station and K clusters of two users each. An iterative design method is then proposed for joint power allocation, precoding, and decoding under imperfect channel estimation. Given channel estimates and the channel error information, K precoders are designed, one for each cluster, based on block diagonalization to eliminate inter-cluster interference. With these precoders, a K-cluster MIMO-NOMA channel can be decomposed into K parallel single-cluster MIMO-NOMA channels, and the original multi-cluster design problem is simplified to a single-cluster design problem. For a single cluster, a power allocation factor between both users is derived by minimizing the maximum mean-squared error (MSE) of the decoded signals inside the cluster, while the corresponding decoders and precoder are derived respectively by minimizing the MSE at each user’s receiver and by minimizing the sum of MSEs of all the users in the system under a power constraint. The derived power allocation factor, precoder, and decoders for a single cluster are iteratively updated until convergence. Computer simulation results demonstrate that the proposed joint design method can significantly improve the bit-error-rate performance as compared with a previous related design without taking the channel error information into account, where the benefit of power allocation would be more notable with an increase of the channel gain difference between the two users in a cluster.

Abstract i
Contents ii
List of Figures iii
List of Tables iv
I.Introduction.......................................................1
II.System Model......................................................5
III.Propsoed Methods.................................................9
A.Inter-cluster Interference Cancellation............................9
B.Imperfect Successive Interference Cancellation....................11
C.MMSE Decoder Design...............................................13
D.Power Allocation..................................................16
E.MMSE Precoder Design..............................................20
F.Iterative Design of Power Allocation, Precoding, and Decoding.....22
G.Complexity Analysis of the Iterative Design.......................23
IV.Simulation Results...............................................25
V.Conclusion........................................................36
Appendix............................................................37
References..........................................................38

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