  Due to increased energy consumption and carbon emissions of the ICT industry,
operators worldwide are focusing on reducing energy consumption of their
networks from financial as well as corporate responsibility perspectives. The
subject of green or energy efficient operation of cellular access network has
attracted a lot of attention in the research community recently. In this
regard, dynamically powering down the radio network equipment has emerged as a
promising solution. In literature, research around this type of techniques has
mainly focused on quantifying the energy saving potential. However, little
efforts have been made towards practical realization of these energy saving
concepts. On the other hand, Wi-Fi networks are undergoing a paradigm shift
towards ubiquity. The main objective of this paper is to provide novel
mechanisms for practically realizing the concept of improving power efficiency
in the cellular access network through opportunistically offloading users to
Wi- Fi networks. These mechanisms are based on the principles of cognitive
network management. Performance evaluation shows the potential of proposed
mechanisms as a viable solution for achieving energy efficiency in the cellular
access network.
