VoIP Quality Assessment in a DVB-RCS Network
- Paper number
IAC-07-B2.6.07
- Author
Mr. Harald Schlemmer, Joanneum Research, Austria
- Coauthor
Mr. Michael Schmidt, Joanneum Research, Austria
- Coauthor
Prof. Otto Koudelka, Graz University of Technology, Austria
- Year
2007
- Abstract
The success of VoIP raises the demand to provide the same service quality as in the Public Switched Telephone network (PSTN) also in satellite-based networks. This paper presents voice quality assessment on the basis of a DVB-RCS system, an analysis of the state of the art and necessary improvements. The authors used the ITU–T E-Model (recommendation G.107) to quantify the speech quality. It is a computational model for assessing the combined effects of variations in transmission parameters which affect speech quality of telephony. Another important topic in the planning of satellite networks is the bandwidth efficiency of VoIP traffic in the forward and return link. The analysis will show that without IP header compression and a powerful encapsulation scheme on Layer 2 efficiency can be as low as 10%. For the measurements a DVB-RCS terminal was pointed to Atlantic Bird III and installed near the Hub of the Telecom provider Belgacom. The tests were grouped into VoIP calls via a provider and Direct IP calls to the LAN of Joanneum Research in Austria. VoIP hard phones under test were the Grandstream GPX 2000, the CISCO 7912 and the SNOM 320. Voice calls with three popular low bit rate codecs, G.729, G.723 and GSM-FR (full rate) were analysed. The DVB-RCS terminal under test supported no QoS mechanisms, but the measurements reflect ideal conditions because the satellite network was used in a carrier with low utilization. That is why the results (R-Value, MOS factor) provide a representative indicator for design and planning of satellite networks and VoIP services. The last chapter presents an overview of important QoS mechanisms for the setup and transmission of VoIP connections.
- Abstract document
- Manuscript document
IAC-07-B2.6.07.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.