Analysis of IMS/NGN Call Processing Performance Using Phase-Type Distributions Based on Experimental Histograms

摘要

The paper describes our further research done with the proposed analytical and simulation traffic models of the Next Generation Network (NGN), which is standardized for delivering multimedia services with strict quality and includes elements of the IP Multimedia Subsystem (IMS). The aim of our models of a single IMS/NGN domain is to evaluate two standardized call processing performance parameters, which appropriate values are very important for satisfaction of users and overall success of the IMS/NGN concept. These parameters are mean Call Set-up Delay E(CSD) and mean Call Disengagement Delay E(CDD). Our latest investigations concern improving the conformity of the analytical results and experimental results obtained using the simulation model, which implements the operation of real network elements according to current standards and research. In this paper the results of calculations using PH/PH/1 queuing systems are presented, in which arrival and service distributions are phase-type distributions computed using maximum likelihood and distance minimization fitting algorithms based on experimental histograms. Presented latest results are compared to these obtained using other, previously investigated queuing systems. Additionally, computational complexity of all examined queuing systems is analyzed. As a result, some general remarks concerning all tested queuing systems and their applicability to NGN are provided.