盲蔽式載波頻率偏移估測法於載波干涉-正交分頻多工系統之效能分析

Performance Analysis of the Blind CFO Estimation in the CI-OFDM System

施佾廷(Yi-Ting Shih)

指導教授 ： 呂振森

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00089

摘要

載波干涉-正交分頻多工(CI-OFDM)系統繼承了正交分頻多工調變(OFDM)技術的高頻譜效率及無符碼間干擾等優點，並可大幅降低均峰值功率比(PAPR)。然而載波頻率偏移(CFO)對於CI-OFDM和CI-OFDMA系統影響很大。使用者的載波頻率偏移在兩系統中皆會產生載波間干擾(ICI)，並且會在CI-OFDMA系統中產生多用戶存取干擾(MAI)，進而使系統效能大幅降低。本論文修改OFDM系統中盲蔽式最小重建錯誤估測法(MRE)，以適用於CI-OFDM系統，並針對接收端本地震盪器為非理想狀態所造成的頻率偏移進行研究。探討使用盲蔽式最小重建錯誤估測法(MRE)時，載波頻率偏移對CI-OFDM和CI-OFDMA系統的影響。在CI-OFDMA系統中，為降低MAI干擾，選用區塊載波配置法，使用MRE載波頻率偏移估測法並補償MAI干擾來改善系統效能。經由電腦模擬分析，此估測法能準確的估測出載波頻率偏移，以提升系統效能。

關鍵字

載波干涉-正交分頻多重存取 ； 載波頻率偏移 ； 最小重建錯誤估測法 ； 多用戶存取干擾

並列摘要

The technique of carrier-interferometry orthogonal frequency division multiplexing (CI-OFDM) inherits many advantages of OFDM technique including high bandwidth efficiency and no inter-symbol interference. It can also reduce peak to average power ratio (PAPR) significantly. However, the performance of both CI-OFDM and CI-OFDMA systems are influenced sensitively by carrier frequency offsets (CFO). The carrier frequency offset of each user will cause inter-carrier interference (ICI) in both systems as well as multiple access interference (MAI) in CI-OFDM systems, which consequently result in severe degradation of the system performance. In this thesis, we modify the blind minimum reconstruction error (MRE) estimation method in the OFDM system to use it in the CI-OFDM system and focus on the carrier frequency offsets induced by the imperfection of local oscillator’s frequency at receiver. We investigate the effects of carrier frequency offsets by using the blind minimum reconstruction error estimation for both CI-OFDM and CI-OFDMA systems. In order to avoid the effect of MAI in the CI-OFDMA system, we choose the block carrier assignment scheme and use the MRE carrier frequency offset estimation method integrated with MAI compensation scheme to improve the system performance. According to the computer simulations, this method gives great estimation of CFOs and therefore increases the system performance for both systems.

並列關鍵字

CI-OFDMA ； carrier frequency offset ； minimum reconstruction error estimation ； multiple access interference

參考文獻

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[20]王思尹，盲蔽式載波頻率偏移估測法於正教分頻多重存取系統效能分析，碩士論文，國立臺北科技大學電機研究所，台北，2013

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