Nicolas Montavont

Prevailing over wires in healthcare environments: benefits and challenges

The objectives of this article are to survey the benefits and challenges posed by the deployment and operation of wireless communications in support of healthcare networks. While the main advantage of wireless communications remains to provide ubiquitous connectivity, thus allowing greater physical mobility and interoperability, a number of engineering issues need to be addressed before this vision is realized. Our intent in this article is to explore some of these issues, including deployment, interference, and mobility, and provide insights for potential solutions.

Analysis and evaluation of mobile IPv6 handovers over wireless LAN

In this paper, we analyze the IPv6 handover over wireless LANs. Mobile IPv6 is designed to manage mobile nodes movements between wireless IPv6 networks. Nevertheless, a mobile node cannot receive IP packets on its new point of attachment until the handover completes. Therefore, a number of extensions to Mobile IPv6 have been proposed to reduce the handover latency and the number of lost packets. We focus on Fast Mobile IPv6 which is an extension of Mobile IPv6 that allows the use of L2 triggers to anticipate the handover. We compare the handover latency in four specific cases: basic Mobile IPv6, the forwarding method of Mobile IPv6, the Anticipated method, and the Tunnel-Based Handover. The results of the handover latency are calculated with the L2 properties of IEEE 802.11b. In particular, we take into account the L2 handover for different configurations of the wireless network.

Enhanced schemes for L2 handover in IEEE 802.11 networks and their evaluations

Given the relatively limited coverage area of 802.11 access points, stations moving inside WLAN are often required to perform a handover. The time needed for a STA to switch from one AP to another is too long for real-time applications to continue operating seamlessly, even if no layer 3 handover is to occur ulteriorly. Many solutions have been proposed for improving the layer 2 handover latency, but we have observed a lack of performance analysis and comparison of the different algorithms. In this article we present two new schemes that aim to enhance L2 handover mechanisms. The main characteristic of these new methods is to reduce the discovery time. We then provide an evaluation of four algorithms in order to analyse and compare solutions in six different scenarios

Toward Mobility and Multihoming Unification- The SHIM6 Protocol: A Case Study

Multihoming and mobility in IPv6 are usually considered as two disjoints concepts. This has lead to the development of the two protocols family separately. However, the new IPv6 terminals are most of the time mobile and are equipped with multiple interfaces. Thus, we need to adopt a new vision toward multihoming and mobility and propose new solutions to manage both of them. In this paper, we focus on the SHIM6 protocol - a new multihoming protocol proposed by the IETF - and we investigate to what extent it can achieve mobility.

Urban 802.11 Community Networks for Mobile Users: Current Deployments and Prospectives

Few years ago some network operators launched a new service called Community Networks, where each subscriber shares its residential Internet connection with other subscribers of the same operator via his 802.11 access point. Due to the high access point density in urban areas, community networks have the potential to offer high data rate wireless Internet access for mobile users, going beyond the currently available hot-spots, which are typically deployed in a limited number of isolated locations (e.g., airports, cafes). Unlike cellular networks, the locations of community network access points is not centrally planned. We evaluate existing community networks using a participatory sensing application called Wi2Me. First, we analyze different metrics in order to characterize community networks. Second, we take advantage of this unique 802.11 network (in terms of density and coverage) to study how mobility can be supported by identifying drawbacks and proposing some possible solutions.

An evaluation of IEEE 802.11 community networks deployments

IEEE 802.11 appears as the most popular technology for wireless access because of its low cost and high data rates capacity. In the recent years a new communication paradigm emerged, called the Community Networking, which takes advantage of existing residential 802.11 access points and is based on sharing some part of the bandwidth to members of the community. We evaluate the 802.11 environment, the quality of link, and the potential of these community networks in the city of Rennes, France. We aim at determining if these networks are offering enough coverage area to be considered as an alternative to cellular networks.

Wi2Me: A Mobile Sensing Platform for Wireless Heterogeneous Networks

With the increasing popularity of WiFi technologies, mobile users may now take advantage of heterogeneous wireless networks. In contrast to cellular networks, community networks, based on sharing WiFi residential accesses, show a high access points density in urban areas but uncontrolled performance. We present Wi2Me Traces Explorer, an extensible mobile sensing application to characterize current deployments. This application allows any mobile user to gather not only access point locations but also their performance in terms of bandwidth, link quality and successful connection rate.

A generic end-host mechanism for path selection and flow distribution

Mobile devices that are equipped with multiple interfaces should choose the best path for each application. In this paper, we propose a new algorithm for path selection on multihomed end-hosts. The algorithm operates in two steps. The first step consists of using a MADM algorithm to allocate score to paths. These scores are then used by a bi-objective tasks assignment function which proposes a global flow to interfaces mapping, which garantee a fair load distribution.

Link triggers assisted optimizations for mobile lPv4/v6 vertical handovers

This document describes a mechanism that enhances mobile IP protocols to smoothly manage handovers for MNs equipped with multiple interfaces and moving across different links. For this purpose, the document provides precise indications on how to use the link layer events information to accelerate IP movement detection and optimize vertical inter-technology handovers. Experimentation results on vertical handovers between WLAN and GPRS networks are also given.

A study of the discovery process in 802.11 networks

Today wireless communications are a synonym of mobility and resource sharing. These characteristics, proper of both infrastructure and ad-hoc networks, heavily relies on a general resource discovery process. The discovery process, being an unavoidable procedure, has to be fast and reliable to mitigate the effect of network disruptions. In this article, by means of simulations and a real testbed, our contribution is twofold. First we assess the discovery process focusing on the values of IEEE 802.11 timers: MinChannelTime and MaxChannelTime. Then, varying these timers, we propose and evaluate an adaptive discovery strategy from which we obtain notable improvements over a fixed timers strategy.