Mihir Kanti Sarkar, G.M. Faysal Ahmad
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Abstract—We briefly discuss three issues related to the relevance and the possible impact of research in the field of green networking, with special attention to the wireless case in this paper. In this context energy efficiency is needed most.
I. SOME DATA ABOUT ICT AND ENERGY
The interplays between the ICT and energy fields are becoming stronger and stronger. On the one hand, ICT is expected to play a key role in reducing the energy consumption is several fields, and in particular in those where most energy is spent, such as transport, buildings, and manufacturing. On the other hand, ICT is emerging as a greedy energy consumer, with a very high growth rate. As regards the first aspect, a recent study of the ICT-ENSURE Project  estimated that ICT can be instrumental for a 26% reduction of the energy consumed in the transport sector, a 5-15% reduction of the energy used by buildings, and a 25-30% reduction of the energy required in manufacturing. These savings add up to 17-22% of the total energy that is consumed in all sectors . Moreover, ICT is expected to significantly improve the energy generation, transport and utilization through the novel concept ofSmart Grid.
This very positive role of ICT on energy consumption also carries an energy cost, since the widespread use of ICT implies the activation of a progressively larger number of equipment, which are today estimated by the Global Action Plan to consume a fraction varying from 2 to 10% of the world power . About one third of this is due to networking. Similar estimates were also obtained by other agencies, such as the Fraunhofer Institute, and ITU. While the fraction of energy consumed by ICT today is not very high, it is expected to grow rapidly, possibly doubling over the next decade . In addition, the energy consumption of ICT is extremely critical in some areas, where the lack of access to reliable and unrestricted power sources constitutes a significant obstacle for the development of ubiquitous ICT infrastructures. These facts have generated a keen interest of researchers in both fields of ICT for energy efficiency and energy-efficient ICT. While the possible relevance and impact of effective ICT solutions for the optimization of the energy consumption is unquestionable, because they target the most energy-greedy sectors, the significance of research efforts in the field of energy-efficient ICT in general, and energy-efficient networking in particular, is not obvious, in spite of the growing number of research initiatives and projects in this field. Among them, we mention the Green Touch initiative launched by the Alcatel-Lucent Bell Labs , and several research projects funded by the European Commission within its 7th Framework Programme, most notably the TREND Network of Excellence  coordinated by Fabio Neri, professor at Politecnicodi Torino in Italy, who passed away in the days of writing this manuscript. This paper is dedicated to him with great affection.
Energy-efficient networking targets the reduction of energy consumption costs, with focus on the energy needed to operate a network. The research that accounts also for the energy con-sumed for the production, deployment and end-of-life disposal of the devices is usually referred to as green networking.
While the two terms, energy-efficient and green networking, are sometimes used in an interchangeable way, most of the research efforts are today devoted to energy efficiency, often motivated by the urgent need to reduce networks operational costs that, for big players such as operators, service providers, or companies that make massive use of networking, are becoming a significant fraction of operational expenditures (OPEX).
In this paper we discuss some issues related to the relevance and the possible impact of research in the...