An enhanced method for the estimation of end-to-end cell delay variation for real-time services

Delay accumulation is intended to be used in path calculations and for accumulating delay parameters in signaling protocols as a call progresses to provide estimates of the end-to-end values of these parameters. Delay parameters such as maximum cell transfer delay and peak-to-peak cell delay variation are important QoS parameters specified end-to-end for real-time services. It has been recognized that the existing delay accumulation method in the ATM Forum standards that is based on addition of quantile values of the delay density overestimates the actual delay and therefore causes underutilization of network resources. We describe the enhanced delay accumulation method which was proposed to the ATM Forum. The enhanced method performs better than the existing method, is simple to implement and requires fewer parameters than the other alternative, the asymptotic method. Furthermore, we demonstrate that the enhanced method is backward compatible with the existing method.