具有多根天線之行動OFDM(A)系統下雙邊載波間干擾消除技術

Bidirectional ICI Cancellation Scheme for Mobile OFDM(A) System with Multiple Antennas

張晉文(Chin-Wen Chang)

指導教授 ： 鍾日龍

中原大學/工學院/電子工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000554

摘要

正交分頻多工(Orthogonal frequency-division multiplexing, OFDM)結合多根傳送多根接收天線是應用在高速無線傳輸大有可為的技術。然而，當使用者設備在高速時，嚴重的載波間干擾(intercarrier interference, ICI)將會破壞OFDM信號的正交性，致使系統性能下降。由載波間干擾通道矩陣的分析得知，ICI效應的有效界限在以中心子載波往外兩邊有限子載波。本論文中，我們提出雙邊決策回授等化器(BD-DFE)來消除行動多入多出正交分頻多工(MIMO-OFDM)系統之載波間干擾效應。BD-DFE由上下兩部份等化器所組成，上半部份使用決策回授等化器得到暫時之訊號預估值，下半部份則利用雙邊決策回授等化器來消除雙邊的載波間干擾而得到最後訊號偵收。在這樣作法下，雙邊的載波間干擾會消除更徹底。模擬結果顯示，我們提出之接收機於移動 OFDM系統在性能和複雜度間提供了良好的平衡。

關鍵字

多入多出 ； 雙邊決策回授等化器 ； 載波間干擾 ； 正交分頻多工

並列摘要

Orthogonal frequency division multiplexing (OFDM) combined with multiple transmitter and receiver antennas (MIMO) is a promising technique for high-speed wireless transmissions. However, severe intercarrier interference (ICI) coming from high mobility of user equipment corrupts the orthogonality of the OFDM and pulls down the system performance. From the analysis of the ICI channel matrix, it is revealed that the interference can be effectively bounded in finite double-side subcarriers centering the desired subcarrier. In this paper, we propose bi-directional decision feedback equalizer (BD-DFE) to tackle ICI problem for the mobile MIMO-OFDM system. The equalizer consists of two-part equalizers. The upper part uses DFE to output tentative decisions. The lower part employs BD-DFE aiming to cancel both pre- and post-cursor ICI to give a finial symbol estimates.
In so doing, double-sided ICI can be removed more completely. Simulation results show that our proposed receiver for the mobile OFDM system provides good tradeoffs between receiver performance and computational load.

並列關鍵字

OFDM ； BD-DFE ； MIMO ； ICI

參考文獻

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