標題: 用於多路徑衰落環境中擷取訊號之波束空間分集結合器
A Beamspace Diversity Combiner for Signal Acqusition in a Multipath Fading Environment
作者: 李宗錫
Lee, Zong-Si
李大嵩
Ta-Sung Lee
電信工程研究所
關鍵字: 衰落;波束分集;等化器;最佳化結合器;最大比值結合器;多路徑;Fading;Beamspace diversity;Equalizer;Optimal combiner;Maximum ratio combiner;Multipath
公開日期: 1997
摘要: 在無線通訊環境下,波束分集技術能夠有效的對抗多路徑衰落.所謂波束
分集系統乃是多個具有不同場型的天線波束能形成不同的接收分支在不同
接收分支所發生的衰落現象是互不相關.如此技術有一個缺乏適應性的抑
制同通道干擾的缺點.在本論文中,吾人提出一個用於區域性訊號接收的
適應性場型分集結合器.此方法主要觀念乃在於一區域內形成多個波束場
型以達到分集來接收衰落訊號.再藉由選擇適當的加權向量使得在此工作
區域內能完成有效的分集結合,並徹底的抑制區域外的同通道干擾.然而,
這只能對抗平坦衰落通道.若在頻率選擇性衰落通道,此波束場型分集結
合器必須結合等化器使用以對抗碼際干擾.電腦模擬結果顯示,在具有多
干擾源及衰落現象之傳播下,結合吾人所提的適應性波束空間分集結合器
及等化器將是一適當解決方案
The beam diversity technique is effective in combating
multipath in wireless communications. In a beam diversity
system, multiple receiving branches are formed with multiple
antenna beams with distinctive patterns. Thesebeams are
synthesized in such a fashion that the fading phenomena observed
at different branches are nearly uncorrelated. The disadvantage
of such a system is the lack of adaptivity for cochannel
interference (CCI) suppression. In this thesis, an adaptive
beam diversity combiner is proposed for sectorized signal
reception. The diversity branches are formed with several
adaptive beamformers whose response patterns encompass an
angular sector in the field-of-view of the receiver. With a set
of juidiciously chosen weight vectors, effective diversity
combining can be achieved inside the sector, and out-of-sector
CCI can be suppressed via nulling. To enchance its tracking
capability, the decision-directed mode is employed upon the
convergence of the combiner. In a frequency selective fading
channel in which intersymbol interference (ISI) is present,a
joint operation of the decision-directed optimum combiner and
linear equalizer is necessary, and will be discussed in the
thesis. Finally, simulation results based on the GSM signal
model are given to confirm the efficacy of the proposed beam
diversity combiner/equalizer.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT860435009
http://hdl.handle.net/11536/63028
Appears in Collections:Thesis