Minimum variance in node power levels: In this scenario, all nodes within the network
are considered equally important and the challenge is to distribute the energy consumption across all nodes in the network as equally as possible. The goal of such an approach could be to maximize the lifetime of the entire network, for example, instead of some nodes expiring sooner than others and thereby continuously decreasing the network size, one could aim at keeping as many nodes alive as long as possible. In the ideal (but practically impossible) case, all nodes would expire at exactly the same time.