QoS analysis of weighted multi-state probabilistic networks via decision diagrams

Network reliability analysis is usually carried out under the simplified hypothesis that the elements of the network are binary entities that can be in one of two mutually exclusive states, perfect functioning or failed. The present paper enlarges this view from two points of view. The elements of the networks are described by multiple states that can represent a variety of different situations, like degradation levels or multiple failure modes. Furthermore, in order to increase the description power of the model, we assign to each state a weight describing a performance attribute of the element in that state. The weights may assume different physical meanings so that different Quality of Service (QoS) indicators may be evaluated. We show that the QoS analysis of a multi-state weighted probabilistic network can be performed by resorting to data structures called Multi-valued Decision Diagrams. Several examples illustrate the methodology.