Research on QoS-Based Networks Node-State

The selection and collection of the node state

information have great impact on the design complexity and

performance of a QoS routing algorithm. Continuous-media

traffic (e.g. audio and video) can tolerate some loss but has rigid

delay constraints. Under this QoS constraint, the node-delay's

Probability Density Function (PDF) is used to character the node

state. The continuous-media traffic is in high burst. So the nodedelay's

PDF is shaped into Normal Distribution through a filter

algorithm. Analysis and simulation show that the tail probability

of the normal distribution can be used to calculate the end-to-end

packet loss rate approximately. Then the variance and mean

value of the PDF can be controlled to calculate a proper packet

loss rate to satisfy the QoS demand. So normal distribution is a

simple, achievable and reasonable description.