Resource Management for IP Telephony Networks

The two key resources in an IP Telephony network are the Internet Telephony Gateways (ITGs) and the IP network. These resources must be effectively managed to simultaneously provide good QoS to calls and maximize network resource utilization. This paper presents two main contributions. First, we design a call admission policy based on congestion sensitive pricing. As the load increases, this policy preferentially admits users who place a higher value on making a call while simultaneously maintaining a high utilization of network resources. We derive the function mapping congestion to price for the admission policy that maximizes revenue. Second, we design a call redirection policy to select the best ITG to serve the call. The policy balances load to improve network efficiency and incorporates QoS sensitivity to improve call quality. Simulation results show the following: (i) Congestion pricing based admission control lowers call blocking probability, increases provider revenue, and improves economic efficiency over a static flat-rate admission control scheme. (ii) Congestion sensitivity in the redirection policy balances load across all the ITGs while QoS sensitivity improves call audio quality. (iii) Incorporating price sensitivity in the redirection policy improves the economic efficiency, i.e., ensures that users who pay more get higher QoS. The techniques studied in this paper can be combined into a single resource management solution that can improve network resource utilization, provide differentiated service, and maximize provider revenue.