Outage-Scale-Based Network Reliability Evaluation for Severe Reliability Requirements

Kengo Nakamura, Takeru Inoue, Masaaki Nishino, Norihito Yasuda

Abstract: As the reliability requirements increase for communication networks, e.g., the seven 9’s reliability for 6G, network operators must evaluate the reliability of their networks more accurately. Since public-communication networks are designed to be less prone to large-scale outages, their (un)reliability should be evaluated per outage scale (the number of disconnected nodes). Traditionally, scale-wise unreliability has been evaluated approximately or requires several hours due to its computational hardness. This paper proposes an efficient algorithm that exactly evaluates scale-wise unreliability by leveraging the given reliability requirements for computation acceleration. We first define a sub-problem that computes the probability of disconnecting x or more nodes and introduce a core algorithm that solves this problem with binary decision diagrams. The core algorithm is used to evaluate the scale-wise unreliability according to the given requirements, e.g., the outage probability or outage scale. The time complexity is theoretically analyzed, and its performance is experimentally verified. The proposed algorithm successfully evaluates in 82 minutes large benchmark networks with 400 links and the seven 9’s requirements; the state-of-the-art algorithm fails to evaluate it within 12 hours.