Résumé:
As modern wireless access networks are moving
towards packet based wireless access one may expect mobile
cellular telephony to be eventually replaced by voice-over-IP
(VoIP) applications. The choice of the codec in these applications
is not straightforward as packet-based power-aware wireless
communications bring new factors into the play. We study
interdependencies between the bitrate, energy consumption, and
the perceived quality provided by the voice codecs. We show that
it is sufficient to equip a software with three codecs only. These
are G.729.E, G.711.1 and G.723.1 codecs. Among those, G.723.E
provides the best trade-off between the involved factors. When
the system is overloaded and/or the power consumption is the
most important metric (i.e., a mobile is running out of power)
G.723.1 provides the best possible capacity and energy savings
at the expense of significant quality degradation. Finally, when
the system is underloaded while the amount of power spent for
running the service is not important G.711.1 provides the best
possible heard quality at exceptionally high power consumption.
