強健式圓形天線陣列多重波束成型技術

Robust Adaptive Uniform Circular Array Beamforming with Multiple-Beam Constraints

蕭碩瑋(Shuo-Wei Hsiao)

指導教授 ： 李枝宏

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.02873

摘要

圓形天線陣列因為具有全方位的特性因此適合做為無線通訊的基地台，我的研究是以窄頻/寬頻圓形天線陣列為基礎的強健式波束成型技術，其中寬頻與窄頻架構的不同在於寬頻天線陣列在每個元件後面接著一個FIR濾波器。
在理想環境下以LCMV等可適性波束成型器可以讓所要的信號保持固定的增益同時可壓抑雜訊以及消除干擾，在我的論文當中討論兩種會使得可適性波束成型技術失敗的情況：方位誤判以及信號同調問題。
本文中參考鄭光鵬的雜訊子空間投影法並將其應用在窄頻圓形陣列上以解決方位誤判問題。
關於同調干擾問題，本文使用虛擬一維陣列配合ITAM演算法並且與傳統的虛擬一維陣列配合前向/後向空間平均法做比較，但是這種方法只適用於所有信號皆在同平面上，所以也提出了二級空間平均法及二級非空間平均法來解決三維入射信號環境下的寬頻以及窄頻圓形陣列信號同調問題。

關鍵字

圓形天線陣列 ； 波束成型

並列摘要

With the characteristics of omni-directional coverage, Uniform Circular Array(UCA) is a suitable structure for base-station.
Thesis focuses on adaptive narrowband/broadband UCA beamforming, the difference between narrowband and broadband UCA is that each sensor of broadband UCA beamformer is connected with a tap-delay-line FIR filter.
Under ideal conditions, UCA with adaptive beamformer such as Linearly Constrained Minimum Variance (LCMV) has the ability of maintaining output power gain of desired signals while it could suppress output noise and reject interference signals.
Two conditions, Direction of Arrival(DOA) mismatch and coherent interference, which make adaptive beamforming fail, are considered in this thesis.
For overcoming DOA mismatch problem, a gradient method proposed by Cheng[1] is applied to narrowband UCA.
For coherent interference, Spatial-DFT is applied to transforming
narrowband UCA to virtual ULA and ITAM is applied to all signals without elevation angle.
As to signals with elevation angle under coherent conditions. 2-stage Spatial Smoothing and 2-stage Without Spatial Smoothing are applied to both narrowband/broadband UCA beamformer.

並列關鍵字

Uniform Circular Array ； Beamforming

參考文獻

[4] 陳治宇,”強健式寬頻陣列多重波束成型技術,”國立台灣大學電信工程學研究所碩士學位論文,June. 2005

[5] 徐振球,’’在同調環境下的可適性寬頻波束成型技術,’’ 國立台灣大學電信工程學研究所碩士學位論文,June. 2005

[6] 王智璋,”具多重波束之強健式可適性陣列信號處理技術,”國立台灣大學電信工程學研究所碩士論文,June. 2004

[8] Bernard Widrow and Kenneth M. Duvall and Richard P. Gooch and William C. Newman,’’Signal cancellation phenomena in adaptive antennas: causes and cures,’’ IEEE Trans. Antennas and Propagation, Vol.30, NO.3, pp.469-478, May. 1982

[9] K. Takao and M. Kikuma ,’’An adaptive array utilizing an adaptive spatial averaging technique for multipath environments,’’ IEEE Trans. Antennas and Propagation, Vol.35, NO.12, pp.1389-1396, Dec. 1987