Cost-Efficient Multicast Routing in Ad Hoc and Sensor Networks

A mobile ad hoc network (MANET) consists of a number of devices equipped with wireless interfaces. Ad hoc nodes are free to move, and communicate with each other using their wireless interfaces. Communications among nodes which are not within the same radio range are carried on via multihop routing. That is, some of the intermediate nodes between the source and the destination act as relays to deliver the messages. Hence, these networks can be deployed without any infrastructure, making them specially interesting for dynamic scenarios like battlefield, rescue operations and even as flexible extensions of mobile networks for operators. Wireless sensor networks (WSNs) follow a similar communication paradigm based on multihop paths. Although wireless sensor nodes are not usually mobile, their limited resources in terms of battery life and computational power pose additional challenges to the routing task. For instance, wireless sensor nodes operate following a duty-cycle, allowing them to save energy while they are sleeping. The different timings for sleep and awake periods across sensors makes the topology change. In addition, these networks are usually densely populated compared to ad hoc networks, requiring very efficient and scalable mechanisms to provide the routing functions. Examples of such techniques gaining momentum nowadays are geographic routing and localized algorithms in general, in which nodes take individual decisions solely based on the local information about itself and its neighbors. These networks have a lot of potential applications, which is one of the reasons why they are receiving so much attention within the research community. ∗Work supported by the “Ramon y Cajal” workprogramme from the Spanish Education Ministry