Predicting users’ next location allows to anticipate their future context, thus providing additional time to be ready for that context and react consequently. This work is focused on a set of LZ-based algorithms (LZ, LeZi Update and Active LeZi) capable of learning mobility patterns and estimating the next location with low resource needs, which makes it possible to execute them on mobile devices. The original algorithms have been divided into two phases, thus being possible to mix them and check which combination is the best one to obtain better prediction accuracy or lower resource consumption. To make such comparisons, a set of GSM-based mobility traces of 95 different users is considered. Finally, a prototype for mobile devices that integrates the predictors in a public transportation recommender system is described in order to show an example of how to take advantage of location prediction in an ubiquitous computing environment.

Road safety has become a main issue for governments and car manufacturers in the last twenty years. The concept of Intelligent Transportation Systems (ITS) is used when talking about communication technologies between vehicles and infrastructure to improve, among others, road safety. In this paper, we propose a warning service to prevent accidents by alerting drivers about accidents and dangerous road conditions. This service includes the definition of a new broadcast dissemination mechanism. A VANET highway scenario is simulated to evaluate how the use of safety schemes decreases the driver's reaction time when an unexpected situation occurs.

Thanks to the research on Vehicular Ad Hoc Networks (VANETs), we will be able to deploy applications on roadways that will contribute to energy efficiency through a better planning of long trips. With this goal in mind, we have designed a gas/charging station advertising system, which takes advantage of the broadcast nature of the network. We have found that reducing the number of total sent packets is important, as it allows for a better use of the available bandwidth. We have designed improvements for a distance-based flooding scheme, so that it can support the advertising application with good results in sparse to dense roadway scenarios.

Wireless communications amongst vehicles bring the opportunity for a wide range of applications, from safety aid to passenger entertainment. The necessity to broadcast information to several-hop neighbors is common to most of the potential application protocols. Broadcast protocols for VANETs based on diverse techniques have already been proposed. In this article, we compare basic broadcast schemes that are not dependent on neighbor knowledge using ns-2 - simple flooding, probabilistic, counter-based, distance-based and traffic-based broadcast. The objective is to obtain general directions for the design of a bandwidth efficient broadcast. Based on this comparison, we have selected distance-based flooding and proposed a scheme that is easy to adjust to the application's necessities.

The recent release of standards for vehicular communications will hasten the development of smart cities in the following years. Many applications for vehicular networks, such as blocked road warnings or advertising, will require multi-hop dissemination of information to all vehicles in a region of interest. However, these networks present special features and difficulties that may require special measures. The dissemination of information may cause broadcast storms. Urban scenarios are especially sensitive to broadcast storms because of the high density of vehicles in downtown areas. They also present numerous crossroads and signal blocking due to buildings, which make dissemination more difficult than in open, almost straight interurban roadways. In this article, we discuss several options to avoid the broadcast storm problem while trying to achieve the maximum coverage of the region of interest. Specifically, we evaluate through simulations different ways to detect and take advantage of intersections and a strategy based on store-carry-forward to overcome short disconnections between groups of vehicles. Our conclusions are varied, and we propose two different solutions, depending on the requirements of the application.