Reliability Analysis of the IP Multimedia Subsystem (IMS)

The IP Multimedia Subsystem (IMS) is a Next Generation Network (NGN) architecture that provides a platform for integrated wireline, wireless and Internet service. Reliable operation of IMS is essential because it provides services that are critical to our day-to-day lives. A systematic methodology to quantitatively assess the reliability IMS considering customer usage patterns, reliabilities of its components and its architecture is an essential first step towards improving and ensuring its reliability and is the focus of this paper. The methodology provides a hierarchical two- step approach to compute IMS reliability. In the first step, the reliability of an individual IMS service is obtained from component reliabilities and IMS architecture. In the second step, the reliability of a single IMS session is obtained from service reliabilities and service distributions. In developing the methodlogy we draw upon our extensive recent experience in the area of architecture-based software reliability analysis. We illustrate the potential of the methodology to assess the influence of difference parameters on IMS reliability with an example.