The current contribution of the ICT industry to the global CO2 emission is at 2 percent and is expected to double by 2020. In many parts of the developing world, diesel generators power the telecom networks. The cost of running a BTS for eight hours on diesel accounts for approximately 64 percent of the TCO of the cell site.

Look at the telecom market in India. The mobile service tariffs in India are lowest in the world, but only 33 percent of the telecom towers get grid power. The cost of running a tower on diesel is double than that of running it on grid power. In a developing country like India, though, the volumes are high, the margins are low. The opex of running cell sites on diesel generators puts undue pressure on the margins. This is a real challenge for telcos.

To make matters worse, the huge carbon footprint of the ICT sector has caught the eye of regulatory bodies. There is a lot of pressure on telcos to go green. The cost of running a cell site on renewable energy like solar power is 3x the cost of grid power. So solar energy will take some more time before it becomes key energy source for telcos.

The Telecom Regulatory Body of India (TRAI) has mandated a new policy to make telcos green. This policy is estimated to cost a whopping $660 billion. But there is no clarity on who will bear the cost.

Every electronic device needs power to run, and there is nothing much that can be done about it. If we look at the relationship between power consumed and device utilization, there is no direct proportional relationship.

A typical device running at 5 to 15 percent of utilization consumes 60 to 90 percent of rated power. There is clearly a lot of wasted power resulting here. If the telcos could reduce this gap between power consumed and device utilization, power bills and carbon emission could be considerably reduced.

If we correlate the key aim of SDN of “separating the control plane from the data plane” with this power management problem, it looks like SDN is the technology that will help telcos in managing the energy demands and their carbon footprint. Let’s see how.

The power management of a device is taken care by the firmware of the device, and the firmware is not changed often. Thus, a device, once added to a network, displays nearly constant power consumption throughout its life in the network.

1. Decouple power management from the device

What if we separate the software part that managed the power of the device from the device? We could do it the way we are doing it in SDN: by having a separate control plane.

Now the control would have the routing algorithm as well as the power management algorithm tightly coupled. If the control plane is diverting traffic that amounts to 5 percent utilization of the device, the device consumes power proportionally. If the device is serving 80 percent of the traffic, it has all the rights to consume power proportionally higher than the device that serving only 5 percent of the traffic.

2. Enable a standby mode

Many a time, during the peak hour, the network devices are hardly serving any traffic. Why not put some devices into standby mode? The control plane of SDN could compute the maximum number of devices required based on the forecasted traffic and the most power-efficient devices that can serve the need. All the other devices are then put into standby mode.