Green Networking and Communications : ICT for Sustainability

Today, reducing global greenhouse gas emissions has become a crucial issue for protecting the earth's environment. This requires the reduction of energy consumption in as many sectors as possible, including home networks. Indeed, in the home environment, networked devices consume a large proportion of household energy. There are three reasons that can explain the high energy consumption of home network devices. Firstly, devices are in idle state for hours when they are not in operation. Secondly, they cannot go to an ultra-low power consumption state when they are not needed. And last but not least, there is an increasing number of home network devices with soaring power consumption in our homes. These home network devices have a long switching time from idle state to sleeping state. Moreover, explicit user commands are required to switch the device from idle state to soft-off state. We can certainly gain energy if the device stays in sleeping state or soft-off state instead of idle state. We propose an Overlay Energy Control Network (OECN) which can switch devices from idle state to sleeping state much more quickly and from idle state to soft-off state automatically. The Overlay Energy Control Network (OECN) is formed by at least one overlay energy control node connected to each home network device. The OECN power management coordinates the power states of all home network devices. The overlay energy control nodes can exchange energy control messages. The devices can be turned on or turned off, or can return to their power states when they receive the OECN messages. So that the OECN can be adaptive to our home network devices, the OECN is developed in two ways: (i) all overlay energy control nodes in the home network are ZigBee nodes. This is a ZigBee Mandatory OECN Solution (ZMS); (ii) one or more devices become the overlay energy control nodes where there are no ZigBee modules on that device. This is a ZigBee Optional OECN Solution (ZOS). In our simulation, we will evaluate our overlay energy-saving solutions with a self-controlled energy solution in three metrics: energy consumption, delay and cost. In the self-controlled solution, the device controls its own power state. The proposed Overlay Energy Control Network provides an efficient energy-saving solution for home network devices. In our use case, the ZigBee Mandatory Solution can gain 21.79 solution. It is an efficient energy-saving solution, but it has a relatively high delay compared to the ZigBee Optional Solution and the self-controlled solution.