Godard Blind Equalizer Error Surface Characteristics: White, Zero-mean, Binary Source Case
نویسنده
چکیده
We study the Godard/CMA error surface in adapting the impulse response coefficients of a finite-length, tapped-delay-line filter to equalize a white, zero-mean, binary (21) source that suffers IS1 due to a linear channel. Our results arise primarily from examination of the expressions for the gradient and the Hessian in the baud-spaced equalizer parameter space of the cost-function in this particular setting. This paper presents results useful in topological assessment of procedures for initializing a gradient descent algorithm on this multimodal surface in the equalizer parameter space.
منابع مشابه
On the Convergence of Blind Channel Equalization
Baud-rate blind equalization algorithms may converge to undesirable stable equi-libria due to diierent reasons. One is the use of FIR lter as an equalizer. It is proved in this paper that this kind of local minima exist for all blind equalization algorithms. The local minima generated by this mechanism are thus called unavoidable local minima. The other one is due to the cost function adopted b...
متن کاملAn enhanced Godard blind equalizer based on the analysis of transient phase
This dissertation proposes an enhanced version of the Godard blind equalizer also known as the constant modulus algorithm (CMA) among blind equalization algorithms, with faster convergence speed. By investigating the surface formed by the minimum points along the ray direction of constant modulus (CM) cost function, it is shown that the trajectory of equalizer coefficient vector asymptotically ...
متن کاملPerformance analysis of Godard-based blind channel identification
We analyze a blind channel impulse response identification scheme based on the cross correlation of blind symbol estimates with the received signal. The symbol estimates specified are those minimizing the Godard (or constant modulus) criterion, for which mean-squared symbol estimation error bounds have recently been derived. In this paper, we derive upper bounds for the average squared paramete...
متن کاملFractionally-spaced constant modulus algorithm blind equalizer error surface characterization: effects of source distributions
The Constant Modulus Algorithm (CMA) [11], [5] is a popular blind equalization algorithm. A common device used in demonstrating the convergence properties of CMA is the assumption that the source sequence is iid (independent, identically distributed). Recent results in the literature show that a finite length fractionally-spaced equalizer allows for perfect equalization of moving average channe...
متن کاملIll-convergence of Godard blind equalizers in data communication systems
Godard algorithms form an important class of adaptive blind channel equalization algorithms for QAM transmission. In this paper, the existence of stable undesirable equilibria for the Godard algorithms is demonstrated through a simple AR channel model. These undesirable equilibria correspond to local but nonglobal minima of the underlying mean cost function, and thus permit the ill-convergence ...
متن کامل