Research Overview

		Research Overview

Current Research

Thesis Title A Unified Mobility Management Architecture for Interworked Heterogeneous Mobile Networks

Award Doctor of Philosophy in Engineering

Advisor Prof. Abbas Jamalipour

Funding Australian Postgraduate Award Industry Scholarship (APAI), Norman I Price Scholarship, and the Research Training Scheme (RTS)

Collaboration SingTel Optus Networks

Abstract

The buzzword of this decade has been convergence: the convergence of telecommunications, Internet, entertainment, and information technologies for the seamless provisioning of multimedia services across different network types. Thus the future Next Generation Mobile Network (NGMN) can be envisioned as a group of co-existing heterogeneous mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions from roaming users are subjected to frequent vertical handoffs across network boundaries.

Therefore, ensuring uninterrupted service continuity during session handoffs requires successful mobility and session management mechanisms to be implemented in these participating access networks. Therefore, it is essential for a common interworking framework to be in place for ensuring seamless service continuity over dissimilar networks to enable a potential user to freely roam from one network to another. For the best of our knowledge, the need for a suitable unified mobility and session management framework for the NGMN has not been successfully addressed as yet. This can be seen as the primary motivation of this research.

Therefore, the key objectives of this thesis can be stated as:

	To propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks
	To propose a framework for facilitating unified real-time session management (inclusive of session establishment and seamless session handoff) across these different networks.

In order to achieve the above goals, an interworking architecture is designed by incorporating the IP Multimedia Subsystem (IMS) as the coupling mediator between dissipate mobile data networking technologies. Subsequently, two different mobility management frameworks are proposed and implemented over the initial interworking architectural design. The first mobility management framework is fully handled by the IMS at the Application Layer. This framework is primarily dependant on the IMS’s default session management protocol, which is the Session Initiation Protocol (SIP). The second framework is a combined method based on SIP and the Mobile IP (MIP) protocols, which is essentially operated at the Network Layer.

An analytical model is derived for evaluating the proposed scheme for analyzing the network Quality of Service (QoS) metrics and measures involved in session mobility management for the proposed mobility management frameworks. More precisely, these analyzed QoS metrics include vertical handoff delay, transient packet loss, jitter, and signaling overhead/cost. The results of the QoS analysis indicates that a MIP-SIP based mobility management framework performs better than its predecessor, the Pure-SIP based mobility management method. Also, the analysis results indicate that the QoS performances for the investigated parameters are within acceptable levels for real-time VoIP conversations. An OPNET based simulation platform is also used for modeling the proposed mobility management frameworks. All simulated scenarios prove to be capable of performing successful VoIP session handoffs between dissimilar networks whilst maintaining acceptable QoS levels.

Lastly, based on the findings, the contributions made by this thesis can be summarized as:

	The development of a novel framework for interworked heterogeneous mobile data networks in a NGMN environment.
	The final design conveniently enables 3G cellular technologies (such as the Universal Mobile Telecommunications Systems (UMTS) or Code Division Multiple Access 2000 (CDMA2000) type systems), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., Broadband Wireless Access (BWA) systems such as WiMAX) to interwork under a common signaling platform.
	The introduction of a novel unified/centralized mobility and session management platform by exploiting the IMS as a universal coupling mediator for real-time session negotiation and management.
	This enables a roaming user to seamlessly handoff sessions between different heterogeneous networks.
	As secondary outcomes of this thesis, an analytical framework and an OPNET simulation framework are developed for analyzing vertical handoff performance. This OPNET simulation platform is suitable for commercial use.

Previous Research

Thesis Title VPN Over a Wireless Infrastructure: Evaluation and Performace Analysis

Award Master of Science (Honours)

Advisors Dr. Seyed A. Shahrestani, School of Computing and IT, University of Western Sydney

Funding UWS Completions Scholarship and the Research Training Schema (RTS)

Abstract

This thesis presents the analysis and experimental results for an evaluation of the performance and Quality of Service (QoS) levels of a Virtual Private Network (VPN) implementation over an IEEE 802.11b wireless infrastructure. The VPN tunnelling protocol considered for the above study is IP Security (IPSec). The main focus of the research is to identify the major performance limitations and their underlying causes for such VPN implementations under study.

The experimentation and data collection involved in the study spans over a number of platforms to suit a range of practical VPN implementations over a wireless medium. The collected data includes vital QoS and performance measures, such as the application throughput, packet loss, jitter, and round-trip delay. It further investigates the contribution of the CPU, inter-packet generation rate, payload data size, geographical distance and the number of simultaneously operating VPNs. Once the baseline measure is established, a series of experiments are conducted to analyse the behaviour of a single IPSec VPN operating over an IEEE 802.11b infrastructure, after which the experimentation is extended by investigating the trends of the performance metrics of a simultaneously operating multiple VPN setup. Finally, the work is extended to a geographically spanned multi-campus site-to-site VPN. The two sites are connected via an IPSec VPN tunnel, which is implemented over a public network infrastructure. Furthermore, the two VPN tunnel end-points are connected to a wireless mesh network and an IEEE 802.11b wireless ad hoc network. The performance measures for each of the above scenarios are comparatively analysed for defining acceptable performance and QoS levels for a wireless VPN.

The overall results and analysis of the investigations concludes that the CPU processing power, payload data size, packet generation rate and the geographical distance are critical factors affecting the performance of such VPN tunnel implementations. Furthermore, it is believed that these results may give vital clues for enhancing and achieving optimal performance and QoS levels for VPN applications over WLANs.

This site was last updated 10/02/08