Energy-efficient networks [Guest Editorial]

Until recently, research and development in the area of communications networks has been mainly targeted at functionality and performance. Only for battery-driven devices, such as mobile handsets and wireless sensors, was energy efficiency a significant consideration. This has changed significantly with the massive use of communications in public, professional, and private life coupled with the increasing cost of energy, and with the recognition of the critical need to reduce CO₂ emissions. These economic and ecological drivers have induced a new research area with energy efficiency of general communications networks as the objective. Today we see energy efficiency becoming a pervasive issue for all communication layers and in all technology areas from microelectronics to systems planning and management.