TITAN: on-demand topology management in ad hoc networks

An ad hoc network is a multi-hop wireless network that is established by a group of mobile nodes without depending on any infrastructure. Due to the disconnected nature of such mobile nodes, a fundamental problem in ad hoc networks is energy-efficient operation to extend the lifetime of the nodes and the network. A promising strategy is to reduce the power consumption of the wireless interface since it is a significant contributer to the overall energy consumption. Essentially, while traffic load defines energy consumption by the wireless interface during active communication [1, 2], idle-time energy dissipation dominates total system energy consumption in the presence of low to moderate traffic [3, 4]. To this end, current approaches allow nodes to switch to a power-save mode where they spend most of their time in a low-power sleep state. However, allowing all nodes to operate in power-save mode imposes additional delay on all communication and can severely limit the capacity of the network as load increases [4]. To compensate for these limitations, some nodes can stay in active mode and serve as stable relays in the network to support low delay and high throughput [3, 4, 5]. Since the choice of nodes that remain active determines both energy consumption and communication quality, the main challenge to any idle-time energy conservation protocol is selecting the set of active nodes through which all traffic flows.