Christer Åhlund

Multihoming with Mobile IP

Mobile IP is the standard for mobility management in IP networks. With today’s emerging possibilities within wireless broadband communication, mobility within networks will increase. New applications and protocols will be created and Mobile IP is important to this development, since Mobile IP support is needed to allow mobile hosts to move between networks with maintained connectivity. This article describes multihomed Mobile IP enabling mobile hosts to register multiple care-of addresses at the home agent, to enhance the performance of wireless network connectivity. Flows can be load-balanced between care-of addresses to achieve a more reliable connectivity. A prototype is also described.

M-MIP: extended mobile IP to maintain multiple connections to overlapping wireless access networks

In future wireless access networks, connectivity to wired infrastructure will be provided through multiple access points with possibly different capabilities and utilization. The demand for increased network performance requires the ability to predict the best overall performance of those access points and to switch access point when the performance changes. Then there is the demand for mobility between networks with maintained connectivity which requires the ability to switch the point of attachment. We propose Multihomed Mobile IP, enabling performance discovery at the networks layer and the capability to decide what AP to use. Mobile IP support is needed to allow mobile hosts to move between networks with maintained connectivity. Multihomed Mobile IP enables mobile hosts to register multiple care-of addresses at the home agent, to enhance the performance of wireless network connectivity. This article describes a simulator evaluation of multihomed Mobile IP.

Extending Global IP Connectivity for Ad Hoc Networks

Ad hoc networks have thus far been regarded as stand-alone networks without assumed connectivity to wired IP networks and the Internet. With wireless broadband communications and portable devices with appropriate CPU, memory and battery performance, ad hoc connectivity will become more feasible and demand for global connectivity through ad hoc networking is likely to rapidly grow. In this paper we propose an algorithm and describe a developed prototype for connectivity between an ad hoc network running the ad hoc on-demand distance-vector protocol and a wired IP network where mobile IP is used for mobility management. Implementation issues and performance metrics are also discussed.

Mobility management for multiple diverse applications in heterogeneous wireless networks

This paper presents a mobility management solution to support both applications who are mobility-aware and those who are not. Mobility management in heterogeneous network environments needs to address the double meaning of the IP address as an endpoint identifier and a location identifier. Application-layer mobility use a non-IP endpoint identifier (e.g. user@realm) while network-layer mobility uses a fixed home IP- address as endpoint identifier. The resolving of the endpoint identifier to a temporary unicast IP address as location identifier needs support from a mobility management system. This paper proposes a mobility support system that integrates the benefits of application-layer SIP mobility with network-layer MIP mobility. A cross-layer information system provides context for mobility adaptation. Context awareness enhances handover decisions, transport performance and media adoption. The network-layer mobility supports the application to locate the destination on- demand for the initial setup of the sessions. The paper includes an initial evaluation of the network-layer mobility part of the solution.

Traffic load metrics for multihomed mobile IP and global connectivity

Support for host mobility an essential and necessary feature for roaming users who connect to wireless networks via access points. Access points may have different capabilities, be connected to different networks and be installed by different providers. A mobile host will discover multiple access points in this environment. In such an environment, a mobile host should be able to use the best available connection to communicate with a correspondent host and perhaps use multiple connections for different hosts. In areas with wireless local area network access, pockets with limited or no coverage could exist. Such restricted connectivity could be compensated by neighbor hosts who form an ad hoc network and relay packets until they reach an access point. This paper describes and discusses a proposed solution towards enabling and supporting connectivity in wireless networks. In the proposed solution the network layer software will evaluate and decide which wireless network connections to use. A Running Variance Metric (RVM) and a Relative Network Load(RNL) are used to measure the traffic load of access points in wireless access networks. RVM and RNL can be efficiently used for both infrastructure networks and ad hoc networks. Multihomed Mobile IP (M-MIP) is an extension of Mobile IP that enables mobile hosts to use multiple care-of addresses simultaneously. The extension enhances network connectivity by enabling the mobile host, the home agent and correspondent hosts to evaluate and select the best connection. A proposed gateway architecture using M-MIP that integrates wired IP networks with ad hoc networks is described. The M-MIP and gateway architecture using the RVM and RNL metrics have been validated with simulation studies and results are presented.

Software Solutions to Internet Connectivity in Mobile Ad Hoc Networks

In recent years wireless Internet access and wireless communications between peers have become the focus of intensive research efforts in various areas of information and communication technologies. Mobility aspects, software development and support for mobile users are currently of major interest within this research area. The Mobile IP protocol is deployed for mobility management of hosts moving between networks. Ad hoc routing is also of major importance for connectivity between communicating mobile hosts without backbone infrastructure. In this paper we propose and describe an integrated connectivity solution and its software implementation between an ad hoc network running the Ad Hoc On-Demand Distance-Vector Protocol (AODV) and a wired IP network where Mobile IP is used for mobility management. The article also describes a project called Mobile City in which our software solutions and support infrastructure are tested and validated.

Maintaining Gateway Connectivity in Multi-hop Ad hoc Networks

The need for maintaining gateway connectivity in an ad hoc access network is vital considering the 80/20 ratio of Internet traffic. There are several proposals of how to integrate gateway forwarding strategies but they all rely on the route discovery procedure of reactive routing protocols. We propose a proactive approach to avoid the delay of the route discovery process. Mobile IP is often suggested to handle macro mobility and we use the advertisements periodically sent by the gateway to update routing tables in the ad hoc network. Since advertisements may arrive to a mobile host through multiple paths, it is important to keep track of the best path to each gateway. We demonstrate the use of a proposed dynamic metric and how to handle location of correspondent hosts. A simulation study demonstrates the usefulness and efficiency of our approach

Context-aware application mobility support in pervasive computing environments

In the future, application mobility can play a crucial role and prove to be an enabler for next generation distributed applications. Application mobility lets an application follow the users while they roam between networks using several devices. In order to achieve seamless application mobility, several issues need to be considered such as device heterogeneity, GUI-adaptation and application loss. Thus, in this paper our contributions are two-fold. Firstly, we present our novel architecture called the Application Mobility Manager (A2M) which provides seamless application mobility. The proposed architecture is context-aware and decentralized. Finally, we present a novel application called the Mobile YouTube Player which is capable of moving between heterogeneous devices and provide users with seamless video experience. We validate the proposed system through rigorous experimentation and user studies based on the real-world test bed and prototype implementation. The results clearly validate that the proposed system can support seamless application mobility.

Integration of ad hoc network and IP network capabilities for mobile hosts

Mobility of user devices connecting to the Internet is of major interest in todays research in networking. Users with portable devices, like laptops and personal digital assistants (PDA), connecting to foreign networks in the Internet want the same functionality as when connected to the home network, as well as accessibility through the home IP address. Ad hoc networking is also of major importance for connectivity between communicating mobile hosts without a backbone infrastructure and for connectivity to access points. For users as well as for applications, network mobility should be transparent. The use of the ad hoc network or the wired IP network should also be managed by the networking software and hidden from applications and users. We propose and describe an integrated connectivity solution and its software implementation between an ad hoc network running the ad hoc on-demand distance-vector (AODV) routing protocol and a wired IP network where Mobile IP is used for mobility management. With the usage of ad hoc networking, a mobile host can use multiple foreign networks to enhance the communication performance. A proposal for multihomed Mobile IP is presented to achieve this.

Port-based Multihomed Mobile IPv6: Load-balancing in Mobile Ad hoc Networks

With todays heterogeneous access to the Internet, users will move between wired and wireless environments and between infrastructure mode and ad hoc mode of wireless communication. When a mobile node moves from an infrastructure connection and connects multihop to an Internet gateway, the performance will degrade and it may not be able to send all of its traffic via a single gateway. This highlights the need of load-balancing between Internet gateways, especially since the behavior of users today involves a multitude of parallel activities generating multiple flows. This paper proposes a solution that enables distribution of individual traffic flows via different Internet gateways instead of using one single gateway. The proposal includes extensions to mobile IP in order to handle flow mobility bindings. The performance of the solution is verified by simulation studies.