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Performance Improvement of AMBE 3600 bps Vocoder with Improved FEC

Authors:
Ali Eksim
Hasan Yetik

Keywords: Digital mobile radio; forward error correction; perceptual evaluation of speech quality; punctured convolutional coding; speech codec; vocoder.

Abstract:
Efficiency and performance of the heavily used electronic devices in the field are always open for debate. As the technology advances, efficiency and performance of the electronic devices increase. Digital communication systems are also getting their share of this development trend. Digital communication systems, such as Digital Private Mobile Radio, Digital Mobile Radio/MotoTRBO, Association of Public-Safety Communications Officials-International Project 25 and Icom-Kenwood NEXEDGE use half rate Advanced Multi-Band Excitation (AMBE) 3600 bps vocoder to provide clean and intelligible voice communication service. Although this half rate vocoder incorporates Forward Error Correction (FEC) coding to protect voice frames, its error correction performance does not meet today’s standards. To improve the FEC performance of the vocoder, in this work, we assess the FEC portion of the vocoder and propose a better performing FEC scheme. The proposed 2/3 rate convolutional code with vocoder frame length reduction provides a 4.41 dB coding gain in the high signal-to-noise region compared to AMBE FEC while preserving audio quality. Since all works are conducted around the vocoder section, improvements can be easily implemented in existing digital communication systems and standards.

Pages: 34 to 38

Copyright: Copyright (c) IARIA, 2017

Publication date: June 25, 2017

Published in: conference

ISSN: 2308-4030

ISBN: 978-1-61208-562-3

Location: Venice, Italy

Dates: from June 25, 2017 to June 29, 2017