EXPERIMENTAL QUANTIFICATION OF VOICE TRANSMISSION QUALITY OF MOBILE-SATELLITE PERSONAL COMMUNICATIONS-SYSTEMS

In this paper the design and analysis of an experiment are presented, which was conducted in order to assess the subjective impact of transm ission delay on mobile voice communications via satellite, This study was conducted using simulated end-to-end propagation delays representa tive of low earth orbit (LEG) and geostationary earth orbit (GEO) netw orks (single and double-hop) in combination with three different speec h coding technologies: 64 kb/s pulse code modulation, 8 kb/s vector-su m excited linear prediction, and 4.15 kb/s improved multiband excitati on (representing wireline, cellular, and mobile-satellite technologies , respectively), Subsequent analysis included computation of the cross -correlation between delay and coding method, from which it was conclu ded that for ''wireline-quality'' and ''communications-quality'' circu its transmission performance somewhat degraded as propagation delay in creased to that of a double-hop GEO circuit, However, for ''communicat ions quality'' circuits employing the 4.15 kb/s speech coding algorith m, transmission performance remained constant as propagation delay inc reased.