Degradation Effect of Cell Loss on Speech Quality Over ATM Networks

Abstract

As recommended, broadband ISDN is expected to carry all the telecommunications services provided in the future, including real time services such as telephony, videoconferencing, and videotelephony. An ATM based network will introduce some impairments not experienced in synchronous networks, such as cell delay variation (jitter) and cell loss. For these real-time services, if a cell is corrupted or lost, retransmission is not possible and so degradation of the signal may occur. In this paper, we study the impact of cell loss on speech quality over ATM networks. Moreover, we compare the results between two different cell loss's replacement techniques: stuffing silent samples and inserting the previous information in the lost cell. Study shows that the second replacement techniques produces better result when compared with the first one. The study also shows that up to 10% of speech cells can be lost over ATM networks while keeping the speech quality over MOS (Mean Opinion Score) of 3.2 for some speech coders. Understanding of the impact of cell loss on speech quality over ATM networks is important for the proper design of network algorithms such as routing, flow control, and management techniques.