The third-generation partnership project (3GPP) and 3GPP2 have standardized the IP multimedia subsystem (IMS) to provide ubiquitous and access network-independent IP-based services for next-generation networks via merging cellular networks and the Internet. The application layer Session Initiation Protocol (SIP), standardized by 3GPP and 3GPP2 for IMS, is responsible for IMS session establishment, management, and transformation. The IEEE 802.16 worldwide interoperability for microwave access (WiMax) promises to provide high data rate broadband wireless access services. In this paper, we propose two novel interworking architectures to integrate WiMax and third-generation (3G) networks. Moreover, we analyze the SIP-based IMS registration and session setup signaling delay for 3G and WiMax networks with specific reference to their interworking architectures. Finally, we explore the effects of different WiMax-3G interworking architectures on the IMS registration and session setup signaling delay.

SIP-Based IMS Signaling Analysis for WiMax-3G Interworking Architectures

An IMS-based network architecture for WiMAX-UMTS and WiMAX-WLAN interworking

In recent years, Internet Protocol (IP) telephony has been a real alternative to the traditional Public Switched Telephone Networks (PSTN). IP telephony offers more flexibility in the implementation of new features and services. The Session Initiation Protocol (SIP) is becoming a popular signaling protocol for Voice over IP (VoIP) based applications. The SIP Proxy server is a software application that provides call routing services by parsing and forwarding all the incoming SIP packets in an IP telephony network. The efficiency of this process can create large scale, highly reliable packet voice networks for service providers and enterprises. We established that the efficient design and implementation of the SIP Proxy server architecture can enhance the performance characteristics of a SIP Proxy server significantly. Since SIP Proxy server performance can be characterized by its transaction states of each SIP session, we emulated the M/M/1 performance model of the SIP Proxy Server and studied some of the key performance benchmarks such as average response time to process the SIP calls and mean number of SIP calls in the system. We showed its limitations, and then studied an alternative M/M/c based SIP Proxy Server performance model with enhanced performance and predictable results. Index Terms—SIP, Performance, M/M/1,M/M/c in the SIP Proxy Server software, which forms a central part of the control plane corresponding to the VoIP data plane. Our key contribution in this paper is obtaining a better understanding of the performance of the SIP Proxy system. We emulated the M/M/1 queuing model proposed in (7), obtained the analytical results and compared them with exper- iments performed on a real SIP Proxy Server. Motivated by our understanding of the SIP Proxy Server software architecture, we proposed a less complex, more predictable, and more realistic SIP Proxy Server based on M/M/c queuing model. Current trends in server architecture make this model more suitable than the M/D/1 model we proposed in (18). In M/M/cmodel, we considered a single proxy server with mul- tiple threads to process all the incoming SIP calls generated from SIP endpoints. To avoid the propagation delay between the proxy servers, we considered a single proxy server in this model. This paper is organized as follows: Section II addresses the background information on SIP and SIP Proxy Server; Section III provides the motivation for this research; Section IV defines the actual M/M/cbased modeling of the SIP Proxy Server, followed by the analytical and experimental results of the M/M/1 and M/M/c models in Section V; Section VI details the comparative study of the results of the SIP Proxy Server models.

Measurements and Analysis of M/M/1 and M/M/c Queuing Models of the SIP Proxy Server

Quality of protection analysis and performance modeling in IP multimedia subsystem

In recent years, transmission of packets over Internet has been a real alternative to the traditional Public Switched Telephone Networks (PSTN). The Internet protocol (IP) offers more flexibility in the design and implementation of features and services. The session initiation protocol (SIP) is a commonly adopted signaling protocol for Voice over IP (VoIP) by many telecommunication industries. Since the signaling system of PSTN, signaling system number 7 (SS7) was designed for high reliability, but IP works on the "best effort" basis which motivated us to study the performance characteristics of SIP control plane. In this paper, we studied an M/M/1 performance model of the SIP proxy server, showed its limitations, and designed an alternative M/D/1 performance model that enhances the SIP proxy server performance.

Comparative Study of M/M/1 and M/D/1 Models of a SIP Proxy Server

The IP multimedia subsystem (IMS) is envisioned as the solution for the next generation multimedia rich communication. Based on an open IP infrastructure, it enables convergence of data, speech, video and mobile network technology. The session initiation protocol (SIP) is the signaling protocol chosen by the 3GPP consortium for IMS. We propose to analyze the IMS network based on the SIP signaling delay and predict performance trends of the network, that allow us to choose parameter values optimally. The paper focuses on the formulation of queuing models for the IMS network and characterization of the SIP server workload, and on a methodology for the design of such networks for optimal performance. Our analysis is based on a careful study of real-life SIP network traffic.

N. Rajagopal

Papers

Modeling and optimization for the design of IMS networks