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Of all communication network types, mobile networks are the largest energy users and the least energy efficient. This is due to how mobile antennas transmit information over a wide area rather than accurately to individual devices.
The energy consumption of mobile antennas is increasing as mobile operators continue to offer more services to a rising number of mobile subscribers, with mobile data in particular putting an additional strain on network capacity.
The GreenTouch Initiative was formed in 2010 by a group of ICT companies with the goal of achieving a 1000-fold improvement in the future energy efficiency of the internet and other networks that support communications, commerce and entertainment.
Having acknowledged the high potential of improving the energy efficiency of mobile networks, antennas became GreenTouch’s first focus area and as a result it revealed a prototype of the Large Scale Antenna System (LSAS). By November 2011, the LSAS had been demonstrated twice in Switzerland by GreenTouch founding member Swisscom.
What is the LSAS and how does it work?
The Large Scale Antenna System aims to offer an increased number of antenna modules and alters the way in which signals are sent to devices by arranging and tuning them in different ways.
The LSAS utilises knowledge of what are known as propagation channels; the physical medium of electromagnetic waves between transmit and receive antennas, to transmit concentrated beams of information selectively to many users at once.
The more antenna modules that are deployed, the higher the concentration of the beams and therefore the lower the power that each antenna needs to send information. Through the use of concentrated beams the need to broadcast over a wide area is removed, while still maintaining the same signal strength and quality of service.
What savings can the LSAS offer the industry?
GreenTouch claims that the LSAS offers a 16-fold increase in energy efficiency in comparison to existing antenna systems. Efficiency can be increased further by deploying more antenna modules at a site. An antenna array comprising of 100 modules would transmit 1% of the energy transmitted by a single antenna with the same quality of service.
GreenTouch says that a commercialised LSAS site deployed at one wireless base station, would achieve potential energy savings of up to 8,700 kilowatt hours per year. The organisation estimates that if this was applied to around five million mobile base stations found worldwide, the technology could lead to savings of up to 43,500 gigawatt hours per year.
Who is supporting the technology and when will it be commercially available?
GreenTouch is supported by some of the world’s largest ICT players and organisations including: AT&T, Bell Labs, China Mobile, Samsung, Huawei, Freescale, CEA-LETI, INRIA (The National Institute for Research in Computer Science and Control), IMEC (Interuniversitair Micro-Elektronica Centrum), France Telecom Orange Labs, Swisscom, Portugal Telecom, and the University of Melbourne’s Institute for a Broadband-Enabled Society (IBES).
As the LSAS is still a prototype technology, it may take some time to develop a market-ready solution. Whether this more precise approach to signalling would suffer in congested urban environments is a concern.
In addition, it is difficult to estimate how much the technology would cost in comparison to existing antenna technology. Any financial gain from energy savings could be offset if the LSAS costs significantly more than existing antenna systems.
