Hong-Yon Lach

IP mobile multicast: Challenges and solutions

This article outlines the challenges of IP multicast over Mobile IP. Then it provides a comprehensive overview of existing multicast solutions to handle mobile sources and receivers in both the Mobile IPv4 and the Mobile IPv6 environments. The solutions are classified into different classes in light of how the network infrastructure is used and the nature of the multicast members (receivers or sources). For each solution, we present a brief overview; we describe the architecture and the proposed protocol; we discuss the advantages and the limitations; and we compare qualitatively all the solutions of each class based on common criteria such as optimal routing, join latency, handover transparency, etc.

Network mobility in beyond-3G systems

This article aims to analyze network mobility issues and requirements in the context of beyond-3G systems, and explore various approaches to the solutions, including the basic approach being pursued within the IETF NEMO working group. It starts with understanding the network mobility scenarios. Then the principle of mobile IP is revisited to serve as the basis for the subsequent discussion on the basic and advanced requirements and approaches for network mobility support. Finally, the network mobility research activities in the EU project OverDRiVE are reported.

Cooperative networks for the future wireless world

Beyond-3G (B3G) systems have been envisaged as an evolution and convergence of mobile/wireless communication systems and IP technologies to offer a multitude of services over a variety of access technologies. To fulfill the vision, it is necessary to understand the requirements with respect to the support of heterogeneity in network accesses, communication services, mobility, user devices, and so on. Besides, it is equally important to promote the necessary research in networking technology by providing a guiding framework of research areas and technical issues with priority. The new architectures and technologies have to address the fundamental assumptions and requirements that govern the design. All these issues are being tackled by the cooperative network group (CoNet) of WWRF; the group is working on a series of white papers outlining B3G visions and roadmap, architectural principles, research challenges, and candidate approaches. This article outlines the CoNet concept, architectural principles, and guidelines for research into cooperative networks assuming that the B3G systems are built over generic IP networking technologies. The article also presents the key research challenges, research framework, and major network components and technologies. The key points are that the system should be layered on demand, encourage reuse if independent modularized functional blocks, support multiple services and service creation, ensure consistent end-to-end connectivity across different access technologies, and cooperate in terms of network control, operations, and maintenance. The architecture includes the endpoints of communications as part of the communications system, and provides a secure and trusted environment in which network functions are performed; the network should self-organize dynamically. Additionally, the article presents the IST WSI architecture proposed to CoNet as reference model along with some approaches to the outlined research challenges. Finally, this study selects three important network components and technologies (i.e., mobility management, multiple access, and moving networks) in order to provide with answers and possible solutions the research challenges presented in earlier sections.

Design and Evaluation of Vertical Handoff Decision Algorithm in Heterogeneous Wireless Networks

The next generation Internet is expected to consist of different wireless networks with diverse performance. Given the complementary characteristics of 3G and WLAN, the combination of 3G and WLAN can achieve anywhere, anytime Internet access and bring benefits to both end users and service providers. For this purpose, an efficient vertical handoff (VHO) algorithm is needed to make intelligent handoff decision. In this paper, we analyze the signal strength model of mobile host (MH) during VHO and present a new motion model-based RSS estimation (MMRE) algorithm. MMRE can adapt to the change of MHs velocity and improve handoff efficiency. We have evaluated MMREs feasibility and effectiveness in simulations and compared its performance with existing handoff decision algorithms

Multicast receiver and sender access control and its applicability to mobile IP environments: a survey

Ensuring secure access control to multicast delivery trees is a challenging issue that is still largely open. Moreover, the impact of host mobility on the access control to the delivery tree has not been investigated. In this article we address the receiver and sender access control problems to the delivery tree and extend the interest to the mobile IP environment by taking into account its particular issues and requirements. To achieve this, we review the existing approaches by classifying them into three classes: digital signature-based solutions, shared secret-based solutions, and hybrid solutions. We also investigate their efficiency and limitations with respect to the specified requirements both in stationary and mobile cases. Our study shows that four main problems arise among the existing approaches. First, few approaches addressed the sender access control problem. Second, both the digital signature- based solutions and hybrid solutions are vulnerable to DoS attacks. Third, the existing solutions do not provide an efficient user exclusion mechanism. Fourth, the defined access control mechanisms result in a number of problems in mobile IP environments.

Mobility-Aware Rendezvous Point for Mobile Multicast Sources

The Internet research community has done a great effort to support mobile receivers in multicast session, but less interest was given to the problem of mobile sources. In fact, building source-specific tree with mobile sources is challenging. Depending on the nature of the mobility of the multicast source, several problems emerge such as the handover transparency, the multicast service interruption, and the reconstruction of the multicast delivery tree after each handover. In this work, we develop a new solution to make multicast source mobility transparent. Our solution introduces a new entity called Mobility-aware Rendezvous Point (MRP) in order to handle the mobility of a multicast source in both intra-domain and inter-domain multicasting. Our solution uses a smooth handover technique between MRP peers and interoperates efficiently with existing multicast routing protocols.

Support of mobile networks in B3G systems

We consider the problem of supporting moving in systems beyond 3G (B3G). We summarize the scope of problem, current solution approaches and the remaining challenges that need to be addressed.