正交分頻多工系統低複雜度訊框同步演算法之效能分析與改進

Performance Analysis and Improvement of the Low-Complexity Frame Synchronization Algorithm for OFDM Systems

陳柏宇(Bo-Yu Chen)

指導教授 ： 呂振森

國立臺北科技大學/電資學院/電機工程系所/碩士(2008年)

摘要

本論文主要是探討正交分頻多工系統下快速且低複雜度訊框同步演算法效能分析與改良。在正交分頻多工系統中訊框同步是系統能維持有效運作的關鍵因素。在正交分頻多工系統訊框同步的相關研究中，已被證明可以在不使用任何外加符號的情況下，以循環前置的相關性達到同步的目地，但此方法複雜度相對較高。因而有後續先將接收訊號量化再計算同步位置的低複雜度同步演算法，但其準確度也相對偏低。在本論文中，將針對前述所提出的低複雜度同步演算法做進一步探討與改進，並結合外加符號的使用，發展出一個低複雜度的訊框同步演算法，先使用低複雜度訊框同步演算法去做訊框起始點範圍的粗略定位，再使用外加符號做小範圍精確定位，此一方法，可在不增加太多計算量的前提下，有效改進系統訊框同步之效能。

關鍵字

訊框同步演算法 ； 正交分頻多工系統 ； 循環前置

並列摘要

In the thesis, we research into the performance of the low-complexity frame synchronization algorithm for OFDM systems and improve it. The frame synchronization of OFDM systems is a critical factor for effective operations of the above system. The relative research shows that the frame synchronization can be achieved by using correlation of cyclic prefix without additional adding symbols, but the computation complexity of this algorithm is high. Thus a low-complexity synchronization algorithm had been proposed. It used the quantized version of the received signal to compute synchronization position with less accuracy. In the thesis, we develop a low complexity synchronization algorithm based on the low-complexity algorithm described above by combining the method of adding extra symbols. In this method, first we use low-complexity frame synchronization algorithm to find coarse synchronization position, and then use additional symbols to find accuracy synchronization position. In this way, our proposed method can improve the performance of frame synchronization at the expense of increasing a little complexity.

並列關鍵字

Frame Synchronization Algorithm ； OFDM ； Cyclic Prefix

參考文獻

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