在本論文中，為了解決以正交分頻多工為基礎所建立的通信系統，在各種不同的條件與環境背景下，為了達成系統在某些特定限制條件下所要求的最佳目標函數值，我們提出了一些對應的調適性資源配置演算法。首先，針對多使用者正交分頻多工系統在下鏈方向，我們利用Lagrange 乘數法並提出一種技術以充分利用在做位元與功率配置過程中所產生的相關計算數據，以降低計算複雜度，但卻保有相同的系統性能。 另外，在具有同頻干擾通道的多細胞下鏈正交分頻多工系統或是離散複頻調變為基礎的數位用戶迴路數據機方面，我們開發一種交錯反覆的位元與功率配置法，使得所有的基地台皆具有最小的傳輸功率且細胞內的每個使用者皆能滿足所要求的服務品質。與修正的貪婪多使用者位元配置法相比較，我們的方法有較低的計算複雜度，而且我們提出的技術在極大部份的資料位元傳輸率中具有較佳的功率增益。
我們也提出一種針對多輸入多輸出正交分頻多工為基礎的多使用者通訊系統在下鏈方向的載波，位元與功率配置演算法。我們使用一種含有2維編碼器-波束形成器的傳輸器以動態多使用者的多輸入多輸出正交分頻多工傳輸技術完成此配置，我們在相同的條件下公平的比較本方法與數種技術。最後，我們就多重存取多輸入多輸出正交分頻多工系統在上鏈方向提出一種配置演算法，以便利用在頻率與空間領域改進功率與頻譜效率。我們的方法，在接收端不需要配備多使用者檢測器而且不會使用任意一對空間可分離的使用者的所有載波具有相同的空間交互相關性之假設，也因此我們所提的技術克服了多重存取多輸入多輸出正交分頻多工系統的這些問題。

In order to solve the objectives with some constraints in various scenarios for orthogonal frequency division multiplexing (OFDM) based systems, we proposed a couple of adaptive resource allocation algorithms. In downlink multi-user OFDM systems, we utilize the Lagrange multiplier method to propose an approach which uses the related calculation results in the procedure for the power and bit assignment. When the model of the co-channel interference channel in downlink multi-cell OFDM systems or in discrete multi-tone (DMT)-based wired digital subscriber loop (DSL) modems is considered, we developed an iterative interlaced bit and power allocation to minimize the total transmit power of all base stations (BSs) while satisfying the required quality of service (QoS) of each user in the cell. The proposed scheme offers the better power gain for higher required data rates than the existing algorithm while having a less computational complexity.
We also propose a sub-carrier, bit, and power allocation algorithm for multiple input multiple output (MIMO) OFDM-based multi-user communication systems on downlink. We exploit a dynamic multi-user MIMO OFDM transmit scheme with two-dimensional (2-D) coder beam-formers in the transmitter to achieve our purpose. We fairly compare the proposed method with several algorithms, such as frequency division multiple access (FDMA), constructive initial assignment (CIA) and Wong’s subcarrier allocation (WSA), under the same conditions. Finally, a resource allocation scheme for multi-access MIMO-OFDM systems in uplink is developed to improve power and spectrum efficiency in the frequency and the space domains. We develop the scheme to remedy some problems for multi-access MIMO-OFDM systems without using multi-user detector (MUD) techniques and the assumption of the identical spatial cross-correlation across all sub-carriers for any pair of spatially separable users.

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