Yu. L. Senchenko

In the article - Analysis of the real time charging mechanism in WLAN/UMTS networks - the accounting procedures of subscribers - resources in WLAN domain of WLAN/UMTS networks are researched, the optimization problem is figured out and an analytical model is developed in order to solve it. The introduction contains a short description of the reasons that led to a convergence of WLAN and UMTS networks, and the problem of real time charging of prepaid subscribers in such networks. The architecture of the WLAN domain of convergent network and the real time charging procedure based on Diameter CCA protocol and principle of resource reservation are then investigated in more detail. This helps to figure out the optimization problem which main objective is to calculate the size of resources been reserved in the billing system such that operator-s expenditures on network exploitation become minimal. To solve the problem, analytical expressions of two parameters are required. The first is the number of credit reservations in the billing system which has to be performed during some period of time. The second is the amount of operator-s loss which is caused by impossibility of the system to make a reservation of a required sum of money. In the article the expression for the first parameter is received for the voice call charging and Internet session charging. Voice call charging analysis is based on the assumption that the voice call duration has Erlang distribution and the voice call cost is considered to be proportional to call holding time. Regarding the Internet sessions the amount of resources consumed is considered to be lognormal and the session cost is proportional to this amount of resources.