數位波束成型技術在無線通訊多路徑傳播環境下之應用

Digital Beamforming in Multipath Channel Environment for Wireless Communication

劉炳龍(Bing-Lung Liu)

指導教授 ： 黃正光

元智大學/工程學院/電機工程學系/碩士(2001年)

摘要

波束成型（Beamforming）是一種方向性濾波（spatial filtering）的技術，可以有效的消除不必要的方向性干擾，以正確的接收訊號。現今，數位波束成型技術已經被廣泛地使用在各個領域當中，包括雷達、聲納、太空探測…等，在新世代行動通訊系統中更是關鍵性的高等訊號處理技術。
在無線通訊系統當中，訊號傳輸過程中會有多路徑傳輸現象的產生，此種通道常用所謂之延遲擴散(delay spread)、都卜勒擴散(doppler spread)及多路徑入射方位角之角度擴散（angle spread）等特性來描述。在本論文之中，我們將探討延遲擴散與角度擴散對傳輸訊號及波束成型性能造成之影響。
此外，我們亦將討論在有共頻帶干擾及靜態通道之狀況下，依延遲擴散與符碼週期之相對大小，來區分窄頻與寬頻傳輸訊號；並針對上述兩種情形，使用各種窄頻與寬頻的數位波束成型接收機架構，與各種演算法，如LMS、RLS、MMSE…等，來研究在不同多路徑傳播環境下各種波束成型之性能，並以電腦模擬實驗驗證之。

關鍵字

波束成型 ； 多路徑傳播環境 ； 無線通訊

並列摘要

Beamforming is a method of spatial filtering, which can eliminate unwanted spatial interferences and receive desired signal accurately. Nowaday, digital beamfoming method is widely used in many areas, like radar, sensor, and space exploration. In next generation of mobile communication system, it will be a key method for signal processing.
In wireless communication system, the process of signal propagation results in multipath propagation. We usually describe this kind of channel as so called delay spread, doppler spread, and incident angles of multipath signal, so called angle spread.
In this paper, we will discuss the effect of delay and angle spread of multipath signal, and performance of beamforming.
And we will also discuss the situation of CCI and static state channel, and discriminate the narrowband and wideband signals from the relative size between delay spread and symbol period. From the above two situations, we use several narrowband and wideband digital beamformer, and algorithms, like LMS, RLS, MMSE,..etc, to research different aspects of beamforming performance in different multipath environments, and confirm the result by computer simulations.

並列關鍵字

Beamforming ； Multipath ； Wireless Communication

參考文獻

[2] A.Paulraj, '''' Space-time processing for wireless communications,'''' IEEE Signal

[4] V. U. Reddy, A. Paulraj, and T. Kailath, ''''Performance analysis of the optimum beamformer in the presence of correlated sources and its behavior under spatial smoothing,'''' IEEE Trans. Acoust., Speech, Signal Processing, Vol. Assp-35, No. 7, July 1987

[5] C. C. The,S. C. Chiu, and S. C. Pei, ''''On the coherent interference suppression using a spatially smoothing adaptive array,'''' IEEE Trans. Antenna Propagat., to be published.

multichannel adaptive equlization for LOS digital communication cCorrupted

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