Design and implementation of an Android library for supporting network-aware applications

In the last years, research about context-aware systems has been particularly intense. Nevertheless, most of the proposed approaches and systems failed to flow from research to the industrial world. We propose ANARC a library that eases the development of network aware applications for smartphones. ANARC does not try to cope with all the possible meanings and variations of context, it instead focuses on a specific restriction of context: the network and associated properties. To make things easier for designers and developers, ANARC adopts a rule and trigger based approach: when the network context matches the one described in a rule, the corresponding notification is sent to the application level. Examples of use of the proposed library are also included

Smartphone-based geolocation of Internet hosts

The location of Internet hosts is frequently used in distributed applications and networking services. Examples include customized advertising, distribution of content, and position-based security. Unfortunately the relationship between an IP address and its position is in general very weak. This motivates the study of measurement-based IP geolocation techniques, where the position of the target host is actively estimated using the delays between a number of landmarks and the target itself. This paper discusses an IP geolocation method based on crowdsourcing where the smartphones of users operate as landmarks. Since smartphones rely on wireless connections, a specific delay-distance model was derived to capture the characteristics of this novel operating scenario

Maximum Accuracy And Use Of Constraints in Network-Based Localization

HIS Ph.D. thesis focuses on network-based localization techniques in two different scenarios: localization of host belonging to the Internet (IP geolocation), and indoor localization of host moving within buildings. Independently from the specific scenario, we advocate the use of constraints (e.g. distance-based, time-based) for improving the localization accuracy. The proposed IP geolocation technique, differently from existing literature, uses smartphones as landmarks to perform measurements from which distances are estimated. Measurements collected in wireless scenarios are noisier than the ones collected in wired scenarios. The use of constraints (time-based, distance-based, access technology-based) reduces the effects of noise, thus improving the accuracy of localization. For the indoor scenario, this thesis proposes a method based on Wi-Fi and external temporal constraints (schedules) to reduce the ambiguity of localization. The approach has been tested in a real scenario and results show that observing users’ movements is sufficient to infer their schedules. The last contribution of this thesis is to derive the Cramér-Rao Lower Bound (CRLB) for IP geolocation. The CRLB has been widely used to define the maximum theoretical accuracy of localization methods. However, as far as we know, it is here used for the first time in the contest of IP geolocation. If the performances of a localization system are close to the CRLB, this means significant improvements are difficult to achieve

Improving Wi-Fi based localization using external constraints

Wi-Fi based localization enables detection of users' position in indoor spaces by means of wireless networking infrastructure. The positive aspects of this solution include the reuse of already deployed systems and thus its reduced costs. On the negative side, Wi-Fi based localization is not particularly accurate, because the common operating conditions are far from the ideal ones. We propose to use external constraints for improving the accuracy of Wi-Fi based localization. A set of known schedules is used to restrict the estimated position of the user to a single room. The schedule for a given user is automatically selected from a set of possible ones by observing user's movements with coarse-grained resolution

Geolocation of Internet hosts: Accuracy limits through Cramer-Rao lower bound

With active IP geolocation, the position of an Internet host is estimated by measuring the network delay from a number of other hosts with known position (usually called landmarks). In particular, after having converted delays into distances, geometrical techniques like trilateration are used to provide the estimated position on a global reference system. In this paper, we derive the Cramer-Rao lower bound (CRLB) of IP geolocation. The CRLB defines a bound on the minimum mean squared error that affects any unbiased estimator. From a practical point of view, the CRLB provides insights about the maximal theoretical accuracy that can be achieved by IP geolocalization methods. The CRLB also provides conceptual tools useful to understand how the position of landmarks and their distribution affect localization performance. Results show that to obtain accuracy levels in the order of a few tens of kilometers, the number of landmarks to be involved can be relevant and/or their distance from the target cannot be too large

Geolocation of Internet hosts using smartphones and crowdsourcing

Knowing the position of an Internet host enables location-aware applications and services, such as restriction of content based on user's position or customized advertising. Active IP geolocation techniques estimate the position of an Internet host using measurements of the end-to-end delay between the target and a number of landmarks (hosts whose positions are known in advance). We present an IP geolocation method that operates in a crowdsourcing perspective and uses mobile devices as landmarks, since their position can be easily computed using the GPS unit. A specific calibration has been included to take into account the particular operating environment which, differently from the past, includes the presence of wireless links