- 學位論文
Dynamic Subcarrier Allocation and Adaptive Modulation with Finite State in Wireless OFDMA System
Dynamic Subcarrier Allocation and Adaptive Modulation with Finite State in Wireless OFDMA System
摘要
現今的無線通訊應用越來越多，人們對於傳輸速率的要求也急速的上升，本篇論文提出一種適應性子載波分配的演算法,稱為”覆換式”演算法（Iterative Exchange algorithm），靠著反覆交換較好通道狀態的子載波，此演算法可以減少使用的子載波處在嚴重衰落的狀態，經由模擬結果得知，和建設性初始化分配演算法(Constructive initial allocation)和可適性調變演算法(Adaptive Modulation)合作，可以使效能得到顯著的改善；在本篇中，我們使用這三個演算法來達到：最大輸出率和最小符號錯誤率。根據模擬結果得知，當系統使用建設性初始化分配演算法(Constructive initial allocation)和可適性調變演算法(Adaptive Modulation)後，可以使輸出率得到顯著的提升，而使用本篇提出的覆換式演算法（Iterative Exchange algorithm）則能再加的改善符號錯誤率的問題
並列摘要
While more and more wireless application and devices are developed, the demand of transmission rate has been increasing rapidly. In this article, a dynamic subcarrier allocation algorithm called iterative exchange (IE) algorithm is proposed. IE algorithm is designed to avoid deep fading by exchanging the subcarrier with good channel condition. By combining construction initial (CIA) and adaptive modulation (AM) algorithms, the performance can be improved significantly by experiment simulation; These three algorithms are implemented to achieve two goals : maximum throughput (MT) and minimum SER (MSER). As the simulation results, system with CIA and AM algorithms can improve the throughput significantly and then combining the IE algorithm can refine the SER.