Enforcing trust, collaboration and power-saving in MANETs

Nowadays mobile data communications are becoming more and more popular and, at same time, people routinely carry along the last generation of mobile devices, called Smartphones. In particular, the ability to connect directly to other similar devices makes smartphones very powerful. The field that we are going to explore is that of Mobile Ad hoc Networks (MANETs). In a network without infrastructure, devices are connected directly or by means of others and this makes collaboration fundamental even though the behaviour, that is, the collaborative attitude of each participant. To provide a more transparent system, we present a mechanism in which a device, through observation of a neighbour, is able to establish the reputation of that neighbour. Afterwards, that value for each node is scattered across the network by means of special packets called Recommendations. Values of reputation obtained with the previous mechanism are parameters of judgement for a Quality of Service (QoS) technique used in communications. Indeed, devices with a bad reputation are strongly penalised when they require a service to others. In particular, the penalisation that a node gets depends on its contribution of collaboration: the less is the collaboration the more is the penalisation. Finally, we focus our research on power-saving. By introducing a novel protocol to cover a weakness of the Dynamic Source Routing (DSR), each device becomes capable of preserving its own energy especially during long and repetitive communications. All prototypes designed in this thesis were implemented and simulated through the Network Simulator 2 (NS2).