Routing to preserve energy in ad hoc networks subject to jamming

Typical applications for ad hoc radio networks require that some or all radios in the network rely on batteries as energy sources. As a result, communication protocols for such networks should be designed to preserve limited energy supplies. Because the choice of a route to a traffic sink influences how often radios must transmit and receive, poor route selection can quickly deplete the batteries of certain nodes. Previous work has shown that a network's lifetime can be extended by assigning higher routing costs to nodes with little remaining energy and nodes that must use high transmitter power levels to reach neighbor radios. Route selection can be complicated by time-varying link conditions. Radios may be subject to interference from other nearby communication systems, hostile jammers, and other, non-communication sources of noise. Because a radio may need to increase its transmitter power or lower its data rate to compensate for the interference, a route that first appears to have only a small cost may later require much greater energy expenditure when transmitting packets. Frequent route selection can help radios avoid using links with interference but can also reduce throughput and increase energy consumption due to the increased number of routing control messages that must be sent. We investigate the effects of time-varying interference on the lifetime of ad hoc networks. It is shown that there is a tradeoff between packet delay and node lifetime. We show that it is possible to design the system to perform well under a wide variety of channel conditions.