RATE FLOW CONTROL OF VOICE TRAFFIC ON AN ETHERNET LOCAL AREA NETWORK

Abstract

Ethernet Local Area Network (LAN) is widely used in the industrial and academic environments for data communications. It has good throughput but unbounded delay characteristics, rendering it unsuitable for voice communications. However, the potential cost benefit of integrating data and voice applications in a single LAN provides a strong motivation for packetised voice transmission. This thesis proposes a rate control scheme to improve the performance of voice users on an Ethernet LAN. The rate control scheme adaptively adjusts the voice source coding rate based on the network load. A simulation model is used to study the performance of the rate control scheme, and the trade-offs between the number of speakers that can be accommodated using rate control and the packet loss distribution are quantified. A subjective listening test is subsequently carried out to assess the quality of various rate-controlled speeches. The simulation and subjective listening test results demonstrate the effectiveness and feasibility of the rate control scheme in limiting voice packet loss on an Ethernet LAN.