Functional Analysis and Design Approach for an Optimal Virtual IP Multimedia Subsystem (IMS) Architecture

Network Functions Virtualization (NFV) is the greatest transformation in Telecommunications industry. It reveals the challenge of transformation from traditional monolithic to optimal virtual architectures, while meeting the standards driven functional, performance constraints and stakeholders conflicting objectives: maximizing flexibility, capacity, autonomy, minimizing expense in terms of financial and human effort (Capex, Opex), etc. Our analysis approach, specifying a customizable policy baseline to arbitrate and optimize for the NFV strategic objectives and enablers, defines an optimal functional architecture adapted to the context at any levels: from orchestration of network functions resources (virtual machines scaling/growth, placement) till an infrastructural equilibrium (integration of multiple virtual IMS systems). To define the optimal functional sets, we explore the multi-objective optimization for decisions trade-offs, incorporating it with the system views and environment, modeled through an adapted model-based Architectural Framework combined with PESTEL and FURPSE analyses. We case study the IP Multimedia Subsystem, as essential for communication services across networks and the only for Voice over 4G/5G. We further discuss our vision: self-regulating system and the related constraints.