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Journal of Electrical and Computer Engineering
Volume 2010, Article ID 902569, 5 pages
http://dx.doi.org/10.1155/2010/902569
Research Article

Acoustic Echo Cancellation Embedded in Smart Transcoding Algorithm between 3GPP AMR-NB Modes

1Media Application Server, Mas DEV, Genband Inc., 3500 Carling Avenue, Ottawa, ON, K2H 8E9, Canada
2Institut Télécom, Télécom Bretagne, UMR CNRS 3192 Lab-STICC, Université Européenne de Bretagne, Technopôle Brest Iroise-CS 83818, 29238 Brest Cedex, France
3DSP Software, Business Group Communication Solutions, Infineon Technologies France-R&D Center, GAIA-2600, Route des Cretes-06560 Sophia-Antipolis, France
4Huawei Technologies Co., Ltd., EU R&D Center, Riesstrasse 25, Munich 80992, Germany

Received 11 November 2009; Accepted 5 August 2010

Academic Editor: Andreas Spanias

Copyright © 2010 Emmanuel Rossignol Thepie Fapi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Acoustic Echo Cancellation (AEC) is a necessary feature for mobile devices when the acoustic coupling between the microphone and the loudspeaker affects the communication quality and intelligibility. When implemented inside the network, decoding is required to access the corrupted signal. The AEC performance is strongly degraded by nonlinearity introduced by speech codecs. The Echo Return Loss Enhancement (ERLE) can be less than 10 dB for low bit rate speech codecs. We propose in this paper a coded domain AEC integrated in a smart transcoding strategy which directly modifies the Code Excited Linear Prediction (CELP) parameters. The proposed system addresses simultaneously problems due to network interoperability and network voice quality enhancement. The ERLE performance of this new approach during transcoding between Adaptive Multirate-NarrowBand (AMR-NB) modes is above 45 dB as required in Global System for Mobile Communications (GSM) specifications.