Adaptive filters with a large number of coefficients are usually involved in both network and acoustic echo cancellation. Consequently, it is important to improve the convergence rate and tracking of the conventional algorithms used for these applications. This can be achieved by exploiting the sparseness character of the echo paths. Identification of sparse impulse responses was addressed mainly in the last decade with the development of the so-called ``proportionate''-type algorithms. The goal of this book is to present the most important sparse adaptive filters developed for echo cancellation. Besides a comprehensive review of the basic proportionate-type algorithms, we also present some of the latest developments in the field and propose some new solutions for further performance improvement, e.g., variable step-size versions and novel proportionate-type affine projection algorithms. An experimental study is also provided in order to compare many sparse adaptive filters in different echo cancellation scenarios. Table of Contents: Introduction / Sparseness Measures / Performance Measures / Wiener and Basic Adaptive Filters / Basic Proportionate-Type NLMS Adaptive Filters / The Exponentiated Gradient Algorithms / The Mu-Law PNLMS and Other PNLMS-Type Algorithms / Variable Step-Size PNLMS Algorithms / Proportionate Affine Projection Algorithms / Experimental Study
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Constantin Paleologu was born in Romania in 1975. In 1998 he received the M.S. degree in telecommunications networks from the Faculty of Electronics, Telecommunications, and Information Technology, University Politehnica of Bucharest, Romania. He also received a masters degree in digital signal processing in 1999, and a Ph.D. degree (MAGNA CUM LAUDE) in adaptive signal processing in 2003, both from the same institution. As a Ph.D. student (from December 1999 to July 2003), he worked on adaptive filters and echo cancellation. Since October 1998 he has been with the Telecommunications Department, University Politehnica of Bucharest where he is currently an Associate Professor. His research interests include adaptive signal processing, speech enhancement, and multimedia communications. He received the ""IN HOC SIGNO VINCES"" award from the Romanian National Research Council in 2009. He was the co-chair of the 2008 International Conference on Computing in the Global Information Technology (ICCGI). He is a member of the Steering Committee of the 2010 International Conference on Digital Telecommunications (ICDT). He serves as the Editor-in-Chief of the International Journal on Advances in Systems and Measurements. He is a Fellow of the International Academy, Research, and Industry Association (IARIA) since 2008.