訊雜比之估計及其於下行正交分頻多工合作式通訊系統頻譜資源分配之應用研究

Using SNR Estimator to Allocate Resource in CRAC for Downlink OFDMA Systems

林孟喬(Meng-Chiao Lin)

指導教授 ： 譚旦旭

國立臺北科技大學/電資學院/電機工程系所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00286

摘要

合作式通訊(Cooperative Communications)在近年來已是一個非常熱門的研究主題。應用中繼站(Relay Stations, RSs)可提高4G行動通訊系統的下行(Downlink)傳輸效能，進一步運用感知無線電(Cognitive Radio, CR)技術則可讓非授權用戶(Unauthorized Users)借用原授權用戶(Authorized Users)的頻帶區段，使無線通訊的頻寬運用更有效率，因而改善頻寬擁塞的問題。本論文針對正交分頻多重存取(Orthogonal Frequency Division Multiple Access, OFDMA)系統估計訊雜比(Signal -to-Noise Ratio, SNR)，通道環境考慮可加性白色高斯雜訊(Additive White Gaussian Noise, AWGN)通道及路徑損失(Pathloss)。我們根據估計的結果，結合中繼站與合作式通訊進行通道分配(Channel Assignment)，以改善系統頻寬應用效率。實驗結果顯示，基於估計訊雜比所預測之傳輸量與理想條件下所獲之傳輸量(Throughput)平均誤差約為3.5%，因此具備應用潛力。

關鍵字

感知無線電 ； 合作式通訊 ； 訊號雜訊比估計 ； 頻譜分配 ； 正交分頻多重存取

並列摘要

In recent years, the research on cooperative communications has received much attention. By using relay stations (RSs) the transmission efficiency of downlink 4G communication system can be significantly improved. Furthermore, with the help of cognitive radio (CR), the unauthorized user can borrow the bandwidth of authorized user, thus increasing the bandwidth usage efficiency, and alleviating the problem of traffic congestion. This thesis aims to estimate the signal-to-noise ratio (SNR) over the orthogonal frequency division multiple access (OFDMA) system, where additive white Gaussian noise (AWGN) channel and path loss are considered. The estimated SNR together with rely station and cooperative communications are then used for channel assignment in order to improve bandwidth usage efficiency. Finally, the transmission capacity evaluated based on the estimated SNR and real SNR are compared. The result shows that the overall error between them is only 3.5%, indicating the potential of the estimation scheme for transmission capacity prediction.

並列關鍵字

Cognitive Radio (CR) ； Cooperative Communications ； Signal to Noise Ratio Estimation ； Channel Assignment ； Orthogonal Frequency Division Multiple Access (OFDMA)

參考文獻

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