Quality of Service for Speech Transmission in Heterogeneous Networks

Project Type: Master/Diploma Thesis
Student: Badic Biljana
Mentor: Gernot Kubin


 Speech and data transmission has been carried over two different networks for a long time. This separation is very uneconomical, because each network needs its own technology. To cross over this gap between telecommunications and information technology, a new technology has been developed, which can transfer voice over a packet-oriented data network. Due to the rapid growth of the Internet, it seems that Voice over IP (VoIP), or IP-Telephony, is the winner. VoIP means transferring voice traffic over a network utilising the Internet Protocol. When a new technology is offered to customers, reliability and quality of service have to be assured. This work is about planning and implementing a test network for VoIP. The target of the work is to test end-to-end speech quality of ITU-T voice coders G.711, G.729, G.722.2 and the ETSI standard voice coder GSM-AMR at different packet loss rates, simulated with a network emulator. The degraded speech samples were generated and their quality was subjectively evaluated. From the results of measurement became clear that the packet loss has a great influence on the degradation of speech quality, therefore one should attempt to minimise these losses as much as possible, for example by the use of Packet Loss Concealment (PLC) techniques.