We propose the Floating Ground Architecture (FGA) for network mobility and ad hoc network convergence. Various factors, including excessive dependence on intelligence in the fixed network, result in the Internet having a de facto logical boundary one hop from the fixed network. To reduce these dependencies, FGA introduces a new logical layer, called Floating Ground, between the fixed network infrastructure and the mobile network, aiming to bridge these different types of network systems. Thanks to the effect of this buffer layer, the architecture: 1) optimizes routes in a deeply nested mobile router arrangement, 2) simplifies mobility event handling under frequent movement of the nodes, and 3) transparently introduces additional functionality with no additional intelligence on the infrastructure side. Through evaluation of our proposed architecture using an actual software implementation running via Direct Code Execution simulation, optimized routes are confirmed with three possible mobility scenarios, demonstrating the handoff duration is dramatically reduced in the short-distance movement scenario, which happens in 78.4%, at maximum, of the handoff events under actual taxi cabs movement in real world. Qualitative analysis of FGA shows it minimizes modification of the network components and existing standardized protocols, and is therefore more suitable for self-organized, distributed network extension than competitive approaches.

The future of Vehicular Ad-Hoc Networks (VANET) will rely mainly on the support of efficient information dissemination protocols, whether we talk about safety applications that warn the driver of an imminent collision, a simple update on traffic conditions, or road-side advertisements. One of the greatest challenges when designing such protocols is how to deliver packets efficiently in a highly mobile environments under intermittent connectivity. Surprisingly, this problem has been under-investigated in the literature. In this paper, we propose, design, and evaluate SERVUS1, a robust dissemination protocol that guarantees packet propagation with high delivery ratio and low overhead. SERVUS includes a new broadcast management mechanism that takes advantage of the inherent behavioral properties of the VANET environment. In particular, the proposed protocol can update isolated nodes (or clusters) with missing information while ensuring homogeneous information dispersal at low overhead. Through a number of analyses, we show that SERVUS is highly efficient with regard to the tradeoff between reliability and cost, and overcomes important issues like the broadcast storm problem and the topological temporal fragility.

Abstract Proxy Mobile IPv6 has been standardized by the IETF recently. It is a network‐based mobility management protocol based on Mobile IPv6. There is significant interest from various standards bodies for its adoption in 4G networks as the key mobility management protocol. It is being seen as the protocol for achieving a common mobile core network, accommodating various access technologies such as WiMAX, 3GPP and 3GPP2 radio networks. One of the key aspects of the protocol is the support for inter‐technology handoffs. The Proxy Mobile IPv6 network allows the mobile node to perform handoff between different access technologies and the network will ensure the terminal obtains the same address configuration as before. However there is no study on the required software function on the host for performing inter‐technology handoffs and with the goal of session survivability across handoffs. This paper analyzes from the mobile node's perspective on the potential approaches for achieving this and without requiring any changes to the host. It explores the use of virtual interface support available in Linux as one of the approaches and demonstrates that it is a simple host configuration and does not require any host stack changes. It also provides the results from the inter‐technology handoff experiments running with our Proxy Mobile IPv6 implementation. Copyright © 2009 John Wiley & Sons, Ltd.

Proxy Mobile IPv6 has been standardized as a network-based mobility management protocol in IETF. To optimize mobile node's handover performance, a context of the mobile node such as its identifier, accounting, authentication and authorization states is expected to be transferred between mobility entities. This paper proposes a simple context transfer mechanism named Context Reflector for Proxy Mobile IPv6 (Context Reflector). Context Reflector carries any kinds of information of mobile nodes. With Context Reflector, the service such as AAA, ROHC and QoS can be quickly re-established after handover of the mobile node. Therefore, the handover latency and the packet loss during handover can be reduced. Comparisons of Context Reflector and other approaches make it clear that Context Reflector is superior in terms of packet loss and handover latency during handover.

We present an analytical, epidemiological, model for the overhead of information dissemination in mobile networks, which finds application in a range of settings, including resource discovery, information dissemination in sensor networks, location services and ad hoc network routing. We consider two principal information dissemination mechanisms, one for which nodes strictly relay information for other nodes, and the other for which they also take advantage of the information already being disseminated to insert their own data to share. The latter mechanism is denoted by path accumulation. We will show that the overhead with path accumulation scales as n3/2and without path accumulation as n5/4. With respect to the connection rate, both scale as radic(lambda). We also identify the cutoff point for path accumulation as xic= 1 - radic(2/radic(n)). Below that threshold, path accumulation should be preferred, while above, path accumulation does not provide substantial benefits. Our model proves extremely accurate against simulation data.

We study the overhead of some mechanisms for information dissemination. We use reactive routing protocols in mobile ad hoc networks as our illustrative example. However, while reactive routing protocols are the main application for our results, they apply to different settings as well, which include publish/subscribe information dissemination mechanisms, information dissemination in sensor networks, and location services. We use a performance measure, defined in [8], which we call the efficiency xi of the information dissemination process, and use this efficiency to evaluate the overhead. The overhead is influenced by the use of a mechanism to increase the amount of information disseminated, at the cost of a higher overhead, called path accumulation. We compare the overhead of routing protocols with and without path accumulation. We observe that path accumulation is always more efficient at disseminating route information in the network, but the gain in efficiency decreases when it is normalized by the number of extra routes discovered, as more is known about the network. This means that the marginal return of path accumulation decreases over not using path accumulation. We propose a new route discovery mechanism which applies to most of the reactive protocols using a route request/route reply exchange. Our route discovery mechanism, denoted adaptive path accumulation adjusts the accumulated path in order to either: scale its bandwidth overhead down as more information is distributed in the network, or improve the network discovery by carefully selecting the routes to be propagated. We assess a range of adaptive path accumulation policies using numerical evaluation and show the effect of these policies on route discovery and packet overhead.

While the IETF standardization process of the Mobile IPv6 and Network Mobility (NEMO) protocols is almost complete, their large-scale deployment is not yet possible. With these technologies, in order to hide location changes of the mobile nodes from the rest of the Internet, a specific router called a home agent is used. However, this equipment generates resilience and performance issues such as protocol scalability and longer paths. In order to solve these problems, we describe and analyze a new concept called Home Agent Migration. The main feature of this solution is the distribution of home agents inside the current Internet topology to reduce distances to end-nodes. As is usually done for anycast routing, they advertise the same network prefix from different locations; moreover they also exchange information about their associations with mobile nodes. This produces a Global Mobile eXchange (GMX), an overlay network that efficiently handles data traffic from and to mobile nodes, and operates home agents as would an Internet eXchange Point (IXP). When a correspondent node needs to exchange packets with a mobile node, the data traffic will be intercepted by its closest GMX home agent and redirected to the home agent to which the mobile node is bound.

The Virtual Mobility Control Domain (VMCD) is proposed to enhance mobility protocols such as Mobile IP and Network Mobility (NEMO). These mobility protocols rely on a single agent called the home agent. This leads to protocol weakness in terms of system robustness and redundant routes. In VMCD, multiple anchor points serving the same home network are placed as home agents at different networks on the Internet backbone. These anchor points advertise the route of the same home network to the backbone from different networks. It is similar to anycast routing approach of root DNS. By genuine routing, packets meant for mobile nodes are always drawn into the closest anchor point and are delivered to the mobile node by the anchor point on behalf of home agent. In addition, even if one of the anchor points fails, another anchor point immediately takes over for the failed anchor point. VMCD provides better routes for mobile nodes and protocol robustness with minimal involvement of end nodes. This paper discusses the VMCD solutions and shows the efficiency and effectiveness of VMCD.

In this paper, virtual mobility control domain (VMCD) is proposed to enhance mobility protocols such as mobile IP and network mobility (NEMO). These mobility protocols rely on a single agent called the home agent. This leads to protocol weakness in terms of system robustness and redundant routes. In VMCD, multiple anchor points serving the same home network are placed as home agents at different networks on the Internet backbone. These anchor points advertise the route of the same home network to the backbone from different networks. It is similar to anycast routing approach of root DNS. By genuine routing, packets meant for mobile nodes are always drawn into the closest anchor point and are delivered to the mobile node by the anchor point on behalf of home agent. In addition, even if one of the anchor points fails, another anchor point immediately takes over for the failed anchor point. VMCD provides better routes for mobile nodes and protocol robustness with minimal involvement of end nodes. This paper discusses the VMCD solutions and shows the efficiency and effectiveness of VMCD.

Abstract The need for ad hoc networks arises when a number of mobile nodes gather in one particular location and form autonomous networks. Ad hoc networks can be adjoined to the Internet, introducing routing and addressing issues that require new features from ad hoc networking protocols. The Internet Gateway can offer global addressability and bidirectional Internet connectivity to every node in the ad hoc network. This can be done in such a way that mobile wireless nodes can migrate between wireless access points that have direct access to the wired Internet and the wireless ad hoc networks that do not have any such local access point infrastructure. Mobile IP can be employed to make such movement seamless (whenever physically possible), even though it occurs between domains with previously incompatible routing models. We believe that IPv6 and Mobile IPv6 afford important advantages for making such attachments, especially regarding router advertisement and address autoconfiguration. In this paper, we show how general ad hoc networks can be connected to the Internet by Internet Gateways, and then describe our specific experiments with Ad hoc On‐Demand Distance Vector Routing (AODV) for IPv6 (AODV6). After demonstrating the basic principles allowing access to the Internet, we then detail our further experiments using Mobile IPv6. Copyright © 2002 John Wiley & Sons, Ltd.