用於扇形分割無線分碼多工通訊系統之波束空-時二維耙狀接收器

Abstract

在本論文中，吾人提出一種用於扇形分割無線分碼多工通訊環境之波束空□時二維耙狀接收器，用以壓抑共通道干擾與使用多路徑分集技術。此接收器分為兩階段處理，首先，利用陣列天線建構出一組適應性波束涵蓋空間中一特定之扇形區，此作法可壓抑在扇形區域外的共通道干擾，並且有效接收在區域內的多路徑訊號。而且，在扇形區藉由選取少量的波束，可大幅降低空□時聯合處理的維度，進而降低接收器的複雜度。經由使用修正的廣義旁波瓣消除器，可以避免多路徑訊號的相互消除效應。其次，在波束後面利用波束空□時聯合處理以建立基於廣義旁波瓣消除器的新型耙狀匹配接收器，進而對抗扇形區域內的共通道干擾以及有效地合併接收多路徑訊號。吾人所提出的二維耙狀接收器可以用於盲蔽化適應性處理，其祇需要使用者的展頻碼、時序以及粗略估計的方向角。最後，吾人將以電腦模擬之結果來驗證所提出的二維耙狀接收器。

In the thesis, a blind beamspace-time (BT) 2-D RAKE receiver is proposed for multiple access interference (MAI) suppression and multipath diversity in a sectored wireless CDMA communication environment. The scheme involves two stages. Firstly, a set of adaptive beamformers encompassing a prescribed sector is constructed on an antenna array, each providing effective suppression of out-of-sector MAI and reception of in-sector desired signals. By selecting a few beams in the sector, the dimension of the space-time data is greatly reduced and this help to lower the complexity of the receiver. Also, using a modified generalized sidelobe canceller (GSC) scheme, the desired signal cancellation phenomenon can be avoided. Secondly, a novel extended RAKE matched filter is performed to combat in-sector MAI and combine the multipath components of the desired signal with a BT joint processor operating on the output from the set of beamformers. The proposed 2-D RAKE receiver can be implemented in a blind adaptive mode, and the only information required is the desired signal's signature, timing and a rough estimate of angle of arrival (AOA).