Wireless Ad-Hoc Networks: from Sensing to Socializing

The first part of this dissertation is related to static Sensor Networks and focuses on one of their most typical and restricting features, that is the limited availability of energy to power sensor nodes. We propose a routing protocol that effectively prolonges the network's lifetime through a new load-balancing technique. The protocol only uses locally available information, thus requiring a very low communication overhead. Moreover, all routing decision are made during a pre-processing stage, taking place before the proper network activity starts. No energy related information needs to be exchanged by nodes after pre-processing, although work-load results to be well distributed among sensor nodes. As a consequence, the strength of energy related attacks from malicious nodes happens to be heavily reduced. In the second part of the dissertation we focus on Pocket-Switched Networks and define of a new unexplored problem related to the area of broadcasting. Broadcasting in Pocket-Switched Networks is usually intended to reach most of the nodes in a network, but does not guarantee to reach all of them. On the contrary, we propose a distributed protocol for the implementation of a reliable broadcast primitive – a broadcasting protocol where every single node is sure to receive any broadcast message circulating in the network. To this end, we consider hybrid networks where nodes can communicate through a short-range communication technology, such as Bluetooth or WiFi, and through a long- range communication infrastructure, such as cellular networks. In our reliable broadcast protocol, nodes use the short-range communication as much as possible and resort to long-range communications only sporadically. The goal is achieved through the inspection of the social links defined by the short-range contacts logged on the portable devices forming the network. Benefits in terms of cost and cellular network offload are showed.