The ability to walk up to any computer, personalize it, and use it as one's own has long been a goal of mobile computing research. We present SoulPad, a new approach based on carrying an auto-configuring operating system along with a suspended virtual machine on a small portable device. With this approach, the computer boots from the device and resumes the virtual machine, thus giving the user access to his personal environment, including previously running computations. SoulPad has minimal infrastructure requirements and is therefore applicable to a wide range of conditions, particularly in developing countries. We report our experience implementing SoulPad and using it on a variety of hardware configurations. We address challenges common to systems similar to SoulPad, and show that the SoulPad model has significant potential as a mobility solution.

The characteristics of ad hoc networks naturally encourage the deployment of distributed services. Although current networks implement group communication methods, they do not support the needs of a mobile node that must locate one or more distributed servers. A node should not need detailed knowledge of network topology to choose servers with which it can communicate efficiently.To this end, manycast is a group communication scheme that enables communication with an arbitrary (user specified) number of group members. Anycast and multicast communication are special cases of manycast in which the target number of group members is one and infinity, respectively. We present manycast and discuss its use as a communication primitive, with specific attention to ad hoc networks. We advocate manycast support at the network layer. A manycast routing protocol enables an application to contact several nearby network nodes that implement a distributed service.We analyze some approaches to manycast, including some application layer implementations. This evaluation supports our claim that manycast must be implemented in the network layer for effective operation in ad hoc networks. We present several extensions to ad hoc routing protocols that can provide manycast support with minimal implementation effort. Through analysis and extensive simulation, we explore the behavior of these approaches to manycast, finally providing recommendations to implementors.

MobileIP, the standard for Internet mobility, enables transparent mobility for a mobile node, but requires communication to take a multihop path through the node's Home Agent. Although a user with a multiple-interface mobile node may desire the ability to communicate locally, perhaps while disconnected from the Internet, MobileIP offers no such support.Contact Networking provides lightweight, localized network communication to a node with diverse network interfaces. The goal is to provide support for local connectivity equivalent to that provided by MobileIP for remote connectivity. The concept of link-layer awareness enables Contact Networking to tailor its operation to different links, using link-layer native services to implement abstract services when possible. Interface management and autoconfiguration insulate the user from concerns about the number and type of interfaces available.In this paper, we motivate the need for localized mobility, and present the design and architecture of Contact Networking. Details of our prototype implementation illustrate the complexities of providing a localized mobility facility.

ARP handles neighbor discovery and address resolution in infrastructure networks, but is inadequate for mobile ad hoc networks (MANETs). Thus, many MANET routing protocols include a neighbor discovery mechanism. This separation of neighbor discovery and address resolution is a fundamental design problem that causes packet loss, particularly when the communication is manycast, a novel variant of multicast communication. Our approach, automatic address resolution, moves address resolution into the routing protocol along with neighbor discovery, correcting these problems.

This paper describes a novel approach to using TCP/IP applications over IrDA (Infrared Data Association) and Bluetooth. First, we look into why so few applications are available over IrDA and what is necessary to make the use of those applications attractive to end-users. Then, we present a new scheme that enables the use of the IrDA communication layer by those applications in a transparent fashion with minimal overhead. We describe the various components necessary to implement such a scheme, IrNET, the name resolver and the discovery manager, and explain how we have implemented those components under Linux. We finish by showing a few examples of use of those components with real applications.

This paper describes a novel approach to using peer to peer wireless links, such as IrDA, Bluetooth and 802.11b. We explain the concept of wireless diversity and its impact on developers and users. We also explore the limitations of classical vertical handoff protocols, such as the need of an infrastructure. We describe our connection diversity framework, upon which is built P-Handoff. We introduce P-Handoff, a new handoff protocol for peer to peer links with fine granularity, which complements vertical handoff and allows to optimise connectivity through multiple wireless links; P-Handoff doesn't require an infrastructure and uses link layer events. We describe some features of our implementation under Linux.