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Proceedings Paper

Voice over IP: improving the quality over wireless LAN by adopting a booster mechanism: an experimental approach
Author(s): Christian Hoene; Iacopo Carreras; Adam Wolisz
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Paper Abstract

The performance of unreliable voice transmission (Voice over IP) over wireless links is measured not by the throughput but by the perceptual speech quality. The speech quality is impaired by packet losses, which are common on wireless links, and by high transmission delays. In this paper, we describe the design and implementation of a novel Speech Property Based Booster that improves the quality of voice over wireless LANs. This booster is in compliance with existing standards and is transparent to other protocols. It uses characteristics of human speech production and features of modern audio codecs to distinguish packets regarding their importance for perceptual quality. Important packets are protected at the link layer by three mechanisms: selective packet loss recovery, redundant transmission and a hybrid solution. These mechanisms have been evaluated using an experimental set-up with commercial wireless LAN equipment. We made measurements of the objective audio quality and analyzed the effects of packet losses, both due to real wireless channels and late packet arrivals. Our experiments show that the booster increases the quality of voice best with the hybrid solution and that the performance of Voice over IP can be improved further.

Paper Details

Date Published: 25 July 2001
PDF: 12 pages
Proc. SPIE 4522, Voice Over IP (VoIP) Technology, (25 July 2001); doi: 10.1117/12.434296
Show Author Affiliations
Christian Hoene, Technische Univ. Berlin (Germany)
Iacopo Carreras, Technische Univ. Berlin (Germany)
Adam Wolisz, Technische Univ. Berlin (Germany)

Published in SPIE Proceedings Vol. 4522:
Voice Over IP (VoIP) Technology
Petros Mouchtaris, Editor(s)

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