用於扇形分割無線通訊系統之適應陣列波束分集/等化及共通道干擾消除技術

Abstract

在本論文中，吾人提出一種用於扇形分割多工通訊環境之波束空-時聯合處理器，用以對抗共通道干擾及等化通道。此方法分為兩階段處理，首先，利用陣列天線建構出一組適應性波束，用以涵蓋空間中一特定之扇形區，此作法可抑制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。其後在各波束後面利用波束空-時聯合處理以建立盲蔽等化技術，進而消除碼際干擾。藉由選取扇形區內之少數波束，吾人可大幅降低空-時聯合處理的維度。在多路徑訊號間隔夠大的情況下，吾人證明利用空間處理即能有效消除碼際干擾。電腦模擬結果顯示，在不同環境下，吾人所提之較低複雜度的聯合處理法能有效消除共通道干擾及碼際干擾。

A beamspace-time processor is proposed for cochannel interference (CCI) suppression and channel equalization in a sectored wireless 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 CCI and reception of in-sector desired signals. Secondly, blind channel equalization is performed to eliminate the inter-symbol-interference (ISI) with a space-time joint processor operating on the output from the set of beamformers. By selecting a few receive beams in the sector, the dimension of the space-time data is greatly reduced, rendering advanced algorithms of channel estimation a feasible solution. For well separated multipath scenarios, a space-only processor is proposed for nulling out the ISI. Through simulation examples, it is shown that the proposed low complexity processor provides an effective joint suppression of ISI and CCI, and exhibits robustness against environmental variations.