Making Networks more efficient - by Peter Judge

Views and Opinions on Green IT (Jun 1 2010)

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   In January this year, Alcatel Lucent announced its Green Touch initiative with the ambitious aim of cutting the energy used by communications a thousand-fold 

   To anyone working in the data center world, that sounds ambitious. Data Centers are fairly well evolved structures and while it may be possible to slash large chunks of their energy use - say as much as fifty percent if you could reduce the energy needed for cooling - data centers aren't currently poised for that sort of energy reduction. 

   What is it that makes the company think that sort of saving can be made in networks? It turns out that a lot of networks depend very heavily on fossil fuels - and there is also a possibility that newer technologies might radically reduce their energy requirements. 

   Alcatel Lucent might have a head start in all this of course, as it owns Bell Labs, the Nobel Prize factory formerly owned by AT&T. And last week I got to see some of this first hand, when Alcatel held an open day at the French wing of Bell Labs, at Villarceaux in France. 

   It was like a massive school science fair, with everyone keen to explain their particular idea, and show us prototypes, from 100Gbps switching and "augmented reality" (iPhones that know what they are looking at) to the so-called "web of things" (sensors and IP addresses on TVs and lights)   

   
   All of it was about making networks cheaper, more effiicient, or more effective. And the bits that interested me most represent substantial cuts in energy.
   
   

   For instance, not everyone realises that in much of the world, mobile phone networks run on diesel. With no reliable power grid, many developing countries use diesel generators to power the cell-towers. As well as the fuel used 24 hours a day to run the radio masts, each operator needs to run a fleet of hundreds of trucks and use more fuel to deliver the diesel to the cell sites. 

   It's often observed that developing countries tend to be rich in sun and wind - so Alcatel has been delivering wireless stations that use a combination of solar and wind energy, to charge batteries which take the place of the diesel generators. The tricky tech from Bell Labs is the monitoring system that makes sure the available power is used to best advantage, and the batteries are charged and discharged through a cycle which prolongs their life. Bell Labs explains it here. 

   A big battery can last eight years if used carefully, or become useless in six months if not, Alcatel scientists explained. 

   Some wireless networks spend almost a third of their budget on diesel, and this technology would allow them to reduce that dependence by 90 percent. 

   
   So we can take a conventional base station and power it by new means. What about reducing the energy required by the base station in the first place?
   
   The answer here is to move to a new generation. Every successive wave of wireless networks has been more efficient than the last - in terms of the amount of energy required per bit transmitted. Bell Labs' open day had some pointers on the direction that will go, in the form of Tom Marzetta, group leader of the communications and signal processing research group at Bell Laboratories in New Jersey.
   
   Future cell towers could use massive numbers of cheap small antennas, instead of the large expensive ones they currently have, if the industry changes its thinking. That would allow very clever signal processing to beam signals in tight beams to each phone using the mast - simultaneously boosting the speed they get, and cutting the power required. 
   
   

   This is a technology proposed for the generation after LTE - the networks which will replace today's 3G services. So this is the technology after next. But Dr Marzetta already presented the idea of Massive MIMO in a paper (PDF) at the 2010 Communication Theory Workshop in Cancun Mexico in May, and he reckons it's one of three front runners for faster and more efficient networks. 

   In amongst the future technology, though, the actual solar-wind base station used some fairly conventional tricks which would be familiar to data center people. It keeps the data processing and battery units cool using free air cooling where possible, for instance. 

   So networks might be different - but some parts of the efficiency puzzle are always the same 
   
   

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