SIMO架構下盲蔽可適性通道鑑定、追蹤與等化之研究

Blind Channel Identification, Tracking and Equalization based on SIMO Structure

彭文達(Wen-Da Peng)

指導教授 ： 黃正光

元智大學/工程學院/電機與資訊工程研究所/碩士(1997年)

摘要

近年來，在單輸入多輸出(SIMO)系統架構的基礎上有一些新的通道鑑
定及等化方法被提出，這些方法通常需要大量的批次矩陣運算例如SVD等
，故較不適用於隨時間變動的通道而這是所有利用多根接收天線之蜂巢式
行動通訊系統的共同問題。

　　在本論文中，我們首先提出利用SIMO架構之相互參考性質以推導出一
套新的盲蔽限制型RLS通道鑑定方式，其具有良好之收斂速度，並完全不
需複雜的矩陣運算，故可用即時可適性之方式成功地鑑定出通道特性，以
實用性而言較批次方法為佳。其次我們亦進一步成功地將此觀念推廣至格
網式架構，使其更具硬體實現上的優點。至於當SIMO通道有共根發生時，
會產生一共通之不可鑑定性問題，我們亦提出所謂之部份可鑑定性之觀念
，及利用一盲蔽最大近似序列估測(MLSE)方法來解決殘餘共根造成之符碼
間干擾(ISI)及還原原始訊號。最後我們利用上述鑑定出之通道參數，使
用強制歸零(Zero Forcing)及最小均方誤差(MMSE)二種準則來設計有限
長度之雙通道等化器組以還原訊號，並以電腦模擬方式來驗証所提出方法
之各種特性。

關鍵字

盲蔽型 ； 通道鑑定 ； 等化器 ； 追蹤 ； 可適性 ； 單輸入多輸出 ； 共根 ； 部份可鑑定性

並列摘要

Recently, some important methods of new channel identification
and equalizer were proposed based on SIMO structure. These
methods require a large amount of batch matrix computations,
e.g. SVD. Thus in changing environments, such as mobile
cellular communications using multiple antennas, their
applications may be limited.

In this thesis, we propose to use the mutual-reference
property of SIMO structure to derive a new blind adaptive
identifier using constrained RLS algorithm which can attain
satisfactory convergent rate and obviate the need of complex
and costly matrix computation. And its adaptive operation also
facilitates tracking of time-varying channels. Thusit is more
suitable for practical real-time applicateion. Next, we extend
the result to the lattice structure, therefore making it more
suitable for hardware implementation. Third, regarding to the
problem that all existing SIMO blind method suffer from an
identifiability condition when some common root exists among
channels , we propose a concept called paritial identifiability
and use a blind MLSE method to sovle the residual ISI caused by
the common root and recover the original signal. Finally, we
use zero forcing and MMSE criteria to design the finite length
equalizer filterbank based on the estimated channel responses.
Computer simulation are included to demonstrate various aspects
of our proposed approach.

並列關鍵字

blind ； channel identification ； equalizer ； tracking ； adaptive ； SIMO ； common root ； paritial identifiability

參考文獻

dimensional data communication systems," IEEE Trans. Communication, VOL 60,pp 275-296,Feb 1981

[3] Evangelos eleftheriou and David D. falconer, "Tracking Properties and Steady-state Performance of RLS Adaptive Filter Algorithms", IEEE Trans. Acoust., Speech, Signal Processing, vol ASSP-34,pp1097-1109, Oct. 1986

[4] Jitendra K. Tugnait, "On Fractionally-spaced Blind Adaptive Equalization Under Symbol Timing Offsets Using Godard And Related Equalizers," IEEE Conf.

pp.1976-1979, 1995

[5] Lang Tong, Guanghan Xu and Thomas Kailath, "Blind Identification and Equalization Based on Second-Order Statistic: A Time Domain Approach," IEEE, Trans. Infom. Theory, VOL 40, NO. 2, pp.340-349, March 1994