Reliability Analysis of Next Generation Mobile Networks

This paper presents an analysis of communication systems in presence of random failures causing performance degradation, especially suitable for next generation core networks based on the IP Multimedia Subsystem (IMS) proposed by Third Generation Partnership Project. In particular, core network signalling servers, namely the Call Session Control Functions (CSCF), are modelled as multi-state elements where each state corresponds to a different performance level of a single server. This approach is becoming more and more relevant to assess the Quality of Service offered by a telecom operator to its subscribers. In order to set up a data session between two terminals, some CSCF must be traversed by call session requests and answers. As a consequence, the number of sessions handled by a single CSCF server per time unit is chosen as a performance measure of a signalling network. The problem of meeting typical requirements for a telecommunication network in terms of service availability is faced by adopting parallel redundancy technique for network elements, given a demand profile.