Voice over IP – – Simulation System
For the development of methods \& algorithms for a robust speech transmission in heterogeneous packet networks, a PC based simulation system has been implemented and set up at IND. The system provides the means to run extensive simulations of VoIP transmission in different networks (e.g. WLAN, UMTS), guaranteeing repeatability and comparability between simulations of different algorithms/parameters. Furthermore, it is also capable of full-duplex real-time VoIP transmissions (over simulated networks) for testing the developed algorithms in real live telephone conversations.
The simulation system is implemented on PCs and consists of:
- VoIP terminals: speech coding, forward error correction (FEC) control & packetization, packet loss concealment
- Network Simulators
- WLAN air interface simulator: utilizes packet loss models derived from measured loss distributions
- UMTS air interface simulator: contains implementation of RLC layer, utilizes off-line simulated bit error patterns
- General Packet Network simulator: utilizes statistical packet loss models