In wireless networks, and ad hoc networks in particular, terminals are powered by batteries with limited lifespan. In networks with infrastructures, however, base stations do not have any limitations as far as energy is concerned; energy constraints are therefore only a problem for mobile units.
For this reason, strategies adopted by these networks are based on energy consumption by the base stations to maximize the lifespan of terminals. This approach does not work for ad hoc networks that do not have a preexisting infrastructure.
Furthermore, in networks with infrastructure, terminals operate independently of each other, using base stations to communicate between themselves. In this case, energy management for a node only concerns its own local applications. This is not the case in ad hoc networks, where nodes are linked and interdependent and cooperate in the routing process.
It is therefore important to develop strategies to maximize the lifespan of stations and thus of the whole network.
The main aim of ad hoc networks is to maintain a maximum number of active mobile terminals. In other words, access to information must be guaranteed wherever and whenever it is required. Energy supply problems are a major hindrance in attaining this aim. The energy constraints of ad hoc networks are essentially due to the use of batteries, which have very limited capacity.