Peer-to-peer content sharing techniques for energy efficiency in wireless networks with fast channel variations

Abstract

According to the International Telecommunication Union, information and communication technology (ICT) was emitting 0.83 GtCO2e (gigatons of carbon dioxide equivalent), contributing to around 2%-2.5% of global greenhouse gas (GHG) emissions in 2007 [1]. With the continuous growth of ICT, especially in developing countries, the GHG emissions are expected to grow at double the rate over the next 10 years [1]. The Global e-Sustainability Initiative research is estimating a 72% increase in ICT energy usage from 2007 to 2020 with around 1.43 GtCO2e emissions in 2020 [1]. In addition, the telecommunications industry is witnessing an explosive increase in data traffic especially with the introduction of wireless modems and smart phones and with the presence of more than one billion wireless subscribers today. The data traffic volume is increasing by a factor of 10 every 5 years, leading to an increase of 16%-20% in energy consumption every 5 years [2]. For instance, in India, the mobile telecom industry is considered the fastest-growing sector with 584.3 million subscribers in 2010-2011 with an annual growth rate of 49.15%. It is estimated that the energy consumption of the Indian Mobile Telecom Industry was 163 PJ (petajoules) with 52.66 million tons emissions of carbon dioxide (CO2) in 2010-2011 [3]. A user who travels a distance of 25 km using public transport such as car or train can result in 1.22 kg of CO2 emissions, compared to 0.11 kg of CO2 emissions for 1 hour of video conferencing with two laptops [4]. A talk of 2 minutes per day on the phone can produce 47 kg CO2e (equivalent) per year, with a total of 125 million tons of CO2e produced by mobile phones in 1 year [5].