Massive efficiency gains hidden in cellphone networks, says study

Call it a blind spot. When it comes to improving energy efficiency, the talk is usually on physical infrastructure that we interact with directly and can see: buildings, cars, machinery and battery-powered electronics. Communication networks, perhaps because they’re largely invisible and operate behind the scenes, are more off the radar. 

But just because electricity doesn’t leak out of windows or fall out of tune doesn’t mean networks can’t be made more efficient. In fact, many of the same factors that reduce the efficiency of other energy-based systems (such as the inability to modulate power output based on real-time demand) negatively affect the performance of today’s information and communication technology networks (ICTs). And as traffic volume on ICTs continues to grow, efficiency will continue to degrade without enhancements.  

As with electrical grids, many existing inefficiencies are legacy issues of bygone eras.

“Communication networks today were designed with bandwidth, speed and cost in mind, not energy consumption or efficiency,” said Thierry Van Landegem, chairman of GreenTouch, a consortium of stakeholders working to improve the energy efficiency of communication and information networks. “We want to make sure they get on the priority list.”

GreenTouch, in a report released today, revealed how much more efficient ICT networks could be if the technologies and proposals developed by its members over the last three years are implemented by 2020. The numbers are dramatic, particularly in mobile networks, which are the most inefficient and also expected to grow the fastest.

The study claims that energy consumption across all networks could be reduced by 90 percent compared to 2010 levels. That’s despite projected traffic volume increases of 88.6 times in the United States, Europe and Japan. 

That means the overall energy efficiency of mobile networks — defined as the ratio of useful traffic carried by the total energy required to support that traffic — would increase 1,043-fold.

Energy efficiency gains in fixed-line and core networks would be less dramatic, the report reveals, but still noteworthy. The modeling shows potential improvements of 449 times in fixed access networks and 95 times in core networks. The smaller gains in core networks are due to their already being relatively energy efficient. 

“We are extremely proud of the progress we’ve made in our first three years, yet there is still much more we can do to improve efficiencies and effectively reinvent technologies in the name of environmental stewardship,” said Van Landegem. “Reducing energy by 90 percent is conservative as we have many projects underway whose effects were not taken into account in that number.” 

GreenTouch members are currently engaged in 16 separate projects to improve energy efficiency at various points along ICT networks.

Why mobile networks are energy inefficient

Broadcasting mobile signals through the air from cellphone towers (also known as base stations) is highly inefficient. 

“If you can shrink the distance between the mobile device and the base station, you improve energy efficiency,” said Thierry Klein, chair of GreenTouch’s Technical Committee.

For that reason, GreenTouch recommends deployment of so-called small cells in dense urban environments. The term “small” can be misleading. Klein said it does not mean the small cells necessarily would be less powerful. They simply would be located closer to users and thus require less energy to do their job. But it also would mean that more small cells would be required to cover the same geographic area.

Klein said that placement would be critically important to achieve the benefits of greater efficiency. The architecture and protocols of small cells also would need to be capable of monitoring demand and powering down individual units during period of low usage, such as at night. 

When I asked Klein about the fact that mobile carriers in the U.S. already seem to be struggling to deploy enough cellphone towers, he conceded that the efficiency models created by GreenTouch do not take into account the cost of deploying this new hardware.

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