Performance evaluation between VBR Speech Coders for Adaptive VoIP applications

The introduction of new variable bit rate (VBR) speech coders has opened up new perspectives for the implementation of adaptive voice over IP (AVoIP) systems. The paper compares different VBR speech coding techniques in a scenario in which the rate of the single sources is dynamically adapted to the workload conditions. The coders compared are the AMR, the M3 R and the G.729. Using source and rate control mechanism models, performance is evaluated in terms of loss probability, offered throughput and mean CMOS with varying numbers of sources. The use of header compression mechanisms is also evaluated