以領航符碼配置技術估計上行正交分頻多重存取系統之通道狀態

Channel Estimation of Uplink OFDMA System Based on Pilot Arrangements

宋家齊(Chia-Chi Sung)

指導教授 ： 譚旦旭

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2014年)

摘要

正交分頻多工 (Orthogonal Frequency Division Multiplexing, OFDM)具高傳輸率，同時對於頻率選擇性衰減通道有良好的對抗性，因此成為當今最受歡迎的無線傳輸技術之一。為提升系統效能，準確估計通道狀態(Channel State Information, CSI)是重要目標。對上行正交分頻多重存取(Orthogonal Frequency Division Multiple Access, OFDMA)系統而言，基地台同時接收多個使用者的上傳訊號，因而需承受多用戶干擾(Multiple Access Interference, MAI)，使得估計的難度提高。相對於盲蔽式(Blind)估測法，利用領航符碼(Pilot Symbol)可得到較準確的估計。本論文採用適應性濾波器(Adaptive Filter)，結合5種簡單的領航符碼配置技術，形成系統1-5，並在雷利衰退通道(Rayleigh Fading Channel)環境下進行一系列模擬實驗。模擬結果顯示系統2、3、4、5可有效降低多用戶之間的干擾，且系統5有最好的估計結果。

關鍵字

正交分頻多重存取 ； 領航符碼 ； 通道估計 ； 適應性濾波器

並列摘要

The orthogonal frequency division multiplexing (OFDM) system has many advantages including high data transmission rate and is robust to the frequency selective fading channel, which make OFDM a popular wireless communication technology in the past decades. As known, accurate channel state estimation is one of the most important goals for system performance enhancement. For the uplink OFDMA system, the base station receives multiple signals from different users which result in the multiple access interference (MAI), and thus increases the difficulty in channel state estimation. As compared to the blind channel estimation, the pilot symbol-based method can attain better estimation results. In this study, an adaptive filter together with five simple pilot symbol arrangements, which consists of system 1, 2, 3, 4, and 5, are presented. A series of simulations is conducted in the Rayleigh fading channel. The results show that system 2, 3, 4 and 5 can effectively reduce the MAI. Among them, system 5 achieves the best performance.

並列關鍵字

Orthogonal Frequency Division Multiple Access (OFDMA) ； Pilot Symbol ； Channel Estimation ； Adaptive filter

參考文獻

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