隨著各種無線通訊服務的提供，使用者對於無線傳輸的需求及品質的要求日益提升。 本篇論文提出了轉換子載波配置演算法（Shift Subcarrier Allocation, SSA），為正交分頻 多重存取系統於下行鏈結，以效用函數為基礎（Utility-based）之資源分配與功率控制的 演算法，藉由效用函數並對子載波進行二維的排序及搜尋，將適宜的子載波分配與通道 增益較佳的使用者，避免使用通道品質較差的子載波，並與現有之演算法相比較。 經由模擬結果得知，建設性初始化分配演算法(Constructive initial allocation)雖有較 佳的效能表現，但需要大量的置換運算時間，轉換子載波配置演算法（SSA）不需要大 量的置換運算時間即可以使效能得到顯著的改善；在本學位論文中，我們使用轉換子載 波配置演算法(SSA)來達到增加輸出率和降低符號、位元錯誤率及傳輸功率的目的。根 據模擬結果得知，當系統以效用函數為基礎結合轉換子載波配置演算法(SSA)後，可以 確保無線傳輸的品質，使輸出率得到顯著的提升，並且降低傳輸功率。 With increasing usage of wireless communications, the requirement of faster transmission rates has also increased rapidly. This thesis is concerned with the problem of dynamic resource allocation and power control. Given the availability of multi-path channels and the transmission rate requirements of various wireless transmission users, it is necessary to consider a joint channel, power and rate assignment scheme that satisfies multimedia multi-rate requirements while using minimal total power. In this thesis, a dynamic subcarrier allocation algorithm, called the shift subcarrier allocation algorithm (SSA), is proposed. The SSA algorithm is designed to avoid allocating much power onto deeply faded bands, reducing transmission power and insuring fairness for each user. To support the diverse quality of services (QoS) requirements of multimedia traffic, the SSA was designed for applying onto OFDMA downlink systems. The goals of SSA are QoS satisfaction, throughput maximization and power sum minimization while satisfying total power or energy constraints.
