- 學位論文
LMDS系統陣列天線波束指向誤差自動修正機制設計
The Design of an Auto-correction Mechanism Using for Beam Pointing Error of LMDS Array Antenna
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摘要
影響LMDS(local multipoint distribution service)系統通訊品質的主要因素除了雨衰外，還有因架設於高樓頂之天線受風力影響造成的天線波束指向誤差。本論文提出一配置在LMDS系統用戶端中具有自動修正波束指向誤差之多波束陣列天線架構。自動修正波束指向的機制包含多波束陣列天線與波束誤差修正法則兩部份；藉由多波束陣列天線尋向，以找出在風力影響下之正確基地台信號來源方向，再透過遞迴最小平方法則(recursive least square, RLS)或模糊基底函數網路(fuzzy basis function network, FBFN) 的指向誤差修正演算法產生預測補償角度，使得陣列天線主波束對準基地台，提升通訊品質。而多波束陣列天線可用由6個天線元構成的一維陣列天線以及由12個天線元構成的二維平面陣列天線來實現；一維陣列天線只能做水平的尋向與指向，二維的平面陣列天線則具有水平及垂直的尋向及掃描指向。在模擬時針對台灣地區的風力分佈對應出適當的波束誤差分佈，將各種風力作用下波束誤差的分佈透過RLS以及FBFN的修正法則去做性能上的模擬，模擬結果顯示FBFN修正法具較佳的暫態響應，且有較小的修正誤差。
並列摘要
In addition to the rain attenuation, the beam pointing error caused by wind force can also effect the performance of the local multipoint distributed system (LMDS). The multibeam array antenna, which can automatically correct the pointing error, at the customer premises equipment (CPE) of LMDS is designed. The mechanism of automatic pointing error correction uses multibeam antenna array to obtain the direction-of-arrival (DOA) of the base-station and uses the beam error correction algorithm to estimate the point error. The multibeam antenna array is implemented with six-element linear array antenna or twelve-element planar array. Planner array can measure the DOA of the base station in azimuth and elevation directions; the linear array can measure the DOA of base station in azimuth direction only. Recursive least square (RLS) and fuzzy basis function network (FBFN) algorithms are used to correct the correct the beam pointing error. In the simulation, the wind force distribution in Taiwan is correlated with the beam pointing errors which are used to evaluate the accuracy of the automatic beam pointing error correction mechanism to compute the performance. The simulation results show that FBFN has batter performance in convergence time and smaller correction error .
參考文獻
[1] Agne Nordbotten, Telenor R&D ,”LMDS system and their application,” IEEE Communication Magazine , pp.150-154, June 2000.
[3] Scott Y. Seidel, “Radio propagation and planning at 28 GHz for local multipoint distribution service(LMDS)”, IEEE, pp.622-625,1998
[4] J Tan and J W F Goddard , “Error analysis one the use of point rainfall statistics to predict path attenuation statistics”, National conference on antennas and propagation,pp271-274,conference Publication No.461,IEE,1999
[7] 張豐榆, “多波束天線陣列設計與尋向定位應用”,私立元智大學電機工程研究所碩士論文,2000
[9] D.P. Grayand and L. Shafai, “Two planner array candidates for LMDS/LMCS subscriber terminal”, IEEE ,pp.2728-2731.