Salvatore Vanini

Adaptive context-agnostic floor transition detection on smart mobile devices

We present a technique for detecting floor changes in an indoor environment and improving pedestrian indoor localization and navigation. Our technique relies on barometric pressure sensors commonly available on smartphones and tablets. We developed an algorithm running on smart mobile devices that can be integrated in any indoor localization system to improve accuracy and support 3D navigation. The main novelty of our technique is that it can work in any type of environment, without any prior knowledge of the building layout, it does not require calibration and it is adaptive. Experimental results show that our method can accurately detect floor changes in any condition without requiring any additional work.

WiSwitch: Seamless Handover between Multi-Provider Networks

Traditionally, global node mobility problem is addressed at networking layer (e.g. Mobile IP and related solutions). However, none of these classes of solution is designed for supporting seamless handover switch between different network providers and technologies, where the node accesses the network from another point of access (with new access procedure) and can change technology access. Starting from the observation that seamless mobility is requested by the applications, we tackle the problem at higher layer. The proposed solution, called WiSwitch, provides always-on, continuous and optimised network services, whenever possible, to the applications independently from lower layers.

Using barometric pressure data to recognize vertical displacement activities on smartphones

A method for detecting major vertical displacements in human activities is proposed.Prediction is based on barometers available on smartphones and inference models.Decision trees are a good choice for their high accuracy and low energy consumption.Barometers offer high accuracy, energy efficiency and independence from position. We introduce a novel, efficient methodology for the automatic recognition of major vertical displacements in human activities. It is based exclusively on barometric pressure measured by sensors commonly available on smartphones and tablets. We evaluate various algorithms to distinguish dynamic activities, identifying four different categories: standing/walking on the same floor, climbing stairs, riding an elevator and riding a cable-car. Activities are classified using standard deviation and slope of barometric pressure. We leverage three different inference models to predict the action performed by a user, namely: Bayesian networks, decision trees, and recurrent neural networks. We find that the best results are achieved with a recurrent neural network (reaching an overall error rate of less than 1%). We also show that decision tree classifiers can achieve good accuracy and offer a better trade-off between computational overhead and energy consumption; therefore, they are good candidates for smartphone implementations. As a proof of concept, we integrate the decision tree classifier in an App that infers user activity and measures elevation differences. Test results with various users show an average recognition accuracy rate of about 95%. We further show the power consumption of running barometric pressure measurements and analyse the correlation of pressure with environmental factors. Finally, we compare our approach to other standard methodologies for activity detection based on accelerometer and/or on GPS data. Our results show that our technique achieves similar accuracy while offering superior energy efficiency, independence from the sensor location, and immunity to environmental factors (e.g., weather conditions, air handlers).

A lightweight localization architecture and application for opportunistic networks

Mobile communication is increasingly becoming part of everyday life. Haggle (www.haggleproject.org) is an innovative project that exploits human mobility for creating an invisible social network to enable communication in the presence of intermittent network connectivity. Mobile devices equipped with network interfaces, may in fact (temporarily) be out of range of the Internet infrastructure, and thereby unable to access Internet services. However, these devices may often be in range of other networked devices, or pass by an area where some type of connectivity is available (e.g. WiFi hotspots) and may be able to perform useful networking transactions involving local exchanges of data, exploiting, in this way, the opportunistic communication. One of the mechanisms for realizing the opportunistic communication is by taking advantage of context information (such as location) for correlating on-line social and physical networks. This, together with the need for information regarding devices locations and the ‘pervasive’ presence of wireless networks in indoor environments, suggested us to implement a lightweight application able to localize mobile devices, exploiting opportunistic networking.

Enhanced DHCP client

The current network architecture for mobile devices presents applications with a synchronous model and employs end-to-end connections. In reality, devices are often disconnected from the network and, while they are disconnected, they can connect to other devices in the neighborhood and exploit the connectivity to allow the user to continue to work. This is the key concept of the Haggle project [1], a ground-up redesign of networking for mobile devices, to support the mobile user scenario. In order to benefit from users mobility, it is necessary to be able to opportunistically switch between (ad hoc) connections, whenever a new opportunity of connection arises. This imposes that connection set-up time must be minimal, considering that the nodes will probably stay in the range of each other for a short time frame. However, we saw that the 802.11 connectivity in Haggle carries significant overhead (especially when switching between Access Point (AP) mode and ad hoc mode, particularly when switching to AP mode) as the DHCP handshake takes a lot of time [2]. This suggested us to implement a new DHCP Client to speed-up the time for retrieving the IP during the connection to an AP, and to effectively implement opportunistic networking.

Demonstrating seamless handover of multi-hop networks

Traditionally, global network mobility problem is addressed at networking layer. However, none of these solution is designed for supporting seamless horizontal and vertical handover. The demonstrated solution, called WiOptiMo, provides always-on, continuous and optimized network services, whenever possible, to the applications independently from lower layers. The whole network can move and all network nodes can continue to work with the optimal connection, until some possible connection exists. This paper shows how the network mobility can be handled at application layer with WiOptiMo and presents a demonstration scenario with a mobile network, whose nodes access audio and video application without being affected by the fact that the network moves and switches from one network access to another.

SIP-based AAA in delay-aware num-oriented wireless mesh networks

Abstract A growing number of mobile nodes that require Internet access is observed. These nodes may be organized in a wireless mesh network in which some of the nodes may serve the access to the Internet and relay other users’ traffic. Such a vision, however, causes the need for carrier-grade reliable Internet sharing solution. This paper presents a CARMNET-XML protocol, which enables to provide Authentication, Authorisation and Accounting AAA functionalities in wireless mesh networks managed by the Delay-Aware Network Utility Maximization System (DANUMS). The presented solution is a part of a CARMNET system, which integrates the utility-oriented resource allocation provided by DANUMS with the IMS architecture. The system allows users to access Internet with a given quality without the need of extending the operator’s infrastructure. Moreover, we define the scenario of the system application involving the use of the proposed protocol that has been experimentally evaluated in a wireless testbed environment

Modeling Social Interactions in Real Work Environments

We present a study for modeling the behavioral patterns of employees and keeping track of the social interactions among people in a real work environment. The main advantage of our approach to capture social interactions in a work environment is the use of off-the-shelf tools and devices - like smartphones available on the market - and the utilization of the discovered patterns for the optimum distribution of employees in a office building. We carried out an experiment in our building at Fernfachhochschule Schweiz and captured data about physical proximity, virtual interactions (i.e., email exchange) and individual performance satisfaction of 20 employees for 8 working days, during their working hours. The objective of the experiment was to investigate the interaction patterns of employees in relation to four aspects: quantity, space, performance and organization. Besides confirming the existence of different social interaction types, we also provide insights in how distance between office spaces affects type and amount of social interaction. Further, we describe the influence of contacts among workers on their performance. Finally, our analysis emphasizes the importance of an employees role in terms of number of physical and virtual interactions.

A Hybrid method for testing routing protocols in mesh networks

Abstract This article presents a hybrid method for testing routing protocols specifically dedicated to mesh networks. The architecture of software routers is described and a graphic environment that would ensure effective configuration of test networks is proposed. The platform for tests of routing protocols presented in the article combines an implementation of routing protocols (the real control plane) with a router data plane simulator. The proposed solution provides an opportunity to test real implementations of routing protocols for any parameters of data plane, not limited by the physical implementation of a test network. The presented platform is based on an open source code

User-profiled platform with advanced navigation support

The increasing spreading of top-medium range mobile phones offering advanced capabilities and the broader use of short-range wireless technologies embedded in them are laying the foundations for the development of new added-value services. In this paper we present an architectural solution for delivering location-based services over heterogeneous mobile phones tailored to the preferences of individual users. We then discuss the performance of a solution for proximity marketing derived from the platform, in terms of localization accuracy and client-application usability.