suzan_bayhanHow can communication networks, e.g., Internet and mobile networks, save energy or go greener as we humanbeings try to do? For example, can we have signs everywhere reading as “Please turn off the Base Stations when leaving” or “Your funny cat video is 100% delivered from your neighborhood”?

Well, the answer is yes, but how it works is a little bit different.


Electricity consumption of telecom operators had an annual growth of 10% and corresponded to roughly 1.5% of worldwide electricity consumption bw. 2007-2012. Today, thanks to the advances in technology, systems are more energy efficient compared to five years ago. However, even coffee machines have Internet connection today! More importantly, only 1 out of 3 people can afford Internet access, and the target is to connect the next billion  for a more fair social and economic development. Hence, ensuring higher energy efficiency in communication networks is imperative. Energy efficiency of a network measures the total energy consumed (e.g., while bits travel through the cables or the air) to deliver one bit to the end user and depends on the hardware as well as the software of the systems.

Turning off the base stations

Generally speaking, decreasing energy consumption is also at the interest of operators as it translates into lower electricity bills. One way to achieve energy saving is to put the base station equipment into low-energy sleep mode when there is low traffic in the coverage area of the BS, or even switching it off– well, maybe not completely but in a particular area, just like we turn off the lights of not the whole home but the kitchen, if no one is there.


But an energy-efficient system does not necessarily mean sustainable and environment-friendly, if the energy fed into the system is not clean, e.g., coal-based. That is why some researchers propose and evaluate the feasibility of networks powered by renewable energy resources and some others articulate why energy-agility metric  rather than energy-efficiency is a better way to measure how green a system is.

Your funny cat video is 100% delivered from your neighborhood

People are encouraged to buy products from local producers, e.g. food from farmers in the neighborhood, as these products do not travel long distances and hence have smaller carbon footprint. Likewise, packets, that are eventually combined to form our favorite movie episode, which travel shorter distances have smaller carbon footprint. When you want to watch the same video clip that your neighbor has just downloaded, why to fetch the bandwidth-hungry video from a server located somewhere in another continent and result in energy waste at every network element on this long path? A new networking paradigm, known as Information-centric networking (ICN), aims to prevent this by serving the users with the packets from the closest provider. Although eco-friendliness is not the primary motivation of ICN, we can still think of it in this context.

Approximate networks: what if we reach the sustainability limits?

As users are intolerant to failures, service providers have to consider the worst-case what-if scenarios, e.g. failure of the servers, the peak load, and develop their networks with certain levels of redundancy. However, the added redundancy comes at the expense of higher energy consumption. Can we have more tolerance to failures, which then decreases the energy consumption? For example, possibly incentivized with a cheaper subscription fee, would you be ok if your Internet connection – yes that means Google or Facebook- may go offline for one hour in a month, or you may occasionally not access to your e-mail for about half an hour? Or would it be very painful if we could not have Internet connectivity after 9:00 pm? These are the questions, which are definitely absurd today, however would they be so if we reach the sustainability limits? Approximate networks considering the lack of some resources propose aiming at sufficiently good performance rather than energy-taxing ideal one.

As these examples show, there are many dimensions communication networks can become greener. However, developing sustainable and eco-friendly networks that are also affordable to everyone is still a big challenge that we should pay more attention to.

Suzan Bayhan
Postdoctoral researcher
University of Helsinki, Department of Computer Science

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