PERFORMANCE MODELING ON CONGESTION CONTROL OF INTEGRATED AAA SERVERS IN 3GPP-WLAN INTERWORKING NETWORKS

The 3GPP organization has proposed 3GPP-WLAN interworking solutions. However, centralized and integrated AAA server is bound to incur the single point failure and system congestion. In order to solve this problem, this paper investigates on the congestion control modeling for the integrated AAA servers. Firstly, a novel integrated AAA system model with communication delay is established. Secondly, the stability of the model is analyzed and solved, so that the critical value is obtained where bifurcation parameter is the feedback delay. Finally, simulation results show that, when the feedback delay is less than the critical value, the system is asymptotically stable; when the feedback delay is greater than the critical value, stability is lost and Hopf bifurcation happens.