When considering the importance of backup power for cell sites,
it seems that mobile network operators are just as vulnerable
to the high price of gas as the rest of us.

Cellular base stations are nearly ubiquitous in developed nations today, making network coverage easy and reliable, so that’s good news. The bad news is that every base station whether bolted to the side of an urban lamp post or sitting atop a distant mountain peak requires constant and reliable power. The rising cost of diesel fuel for generators is spurring mobile carriers to increasingly turn to energy-efficient hardware and alternative resources.

Alcatel-Lucent is experimenting with the use of solar panels for cell site power in equatorial regions.

In the United States, most base stations already have some battery backup power, but there is enough inconsistency among carriers that regulators are concerned about communications reliability in future emergencies. Nobody knows the full scope of the problem, however. “It is well-documented that there is a deficiency in this area,” said FCC spokesman Robert Kenny.

That documentation stems from an investigation by the commission’s Public Safety & Homeland Security Bureau last year, which resulted in the report “Recommendations of the Independent Panel Reviewing the Impact of Hurricane Katrina on Communications Networks.” Among the recommendations is a rule requiring 24 hours of backup power for central sites and 8 hours for remote sites. The rule is not yet official because of a legal challenge from the CTIA and Sprint Nextel, asserting burdens of logistics and cost. Last month, a Federal appeals court sent the rule back to the FCC for clarification; now it’s likely to take effect later this year or next year with various compromises and exceptions. When that happens, the FCC will be able to collect and analyze data showing where the problems are most egregious.

Sheikh: There are conflicting trends for base station power requirements.

BACKUP DATA
Carriers are understandably reluctant to share details of their site backup power methods. Verizon Wireless is not among the companies fighting the FCC plan and is widely commended in the industry for having redundant power supplies and heavy use of diesel generators, but still considers details of its backup processes to be a confidential and a competitive advantage, said spokesman Jeffrey Nelson.

That importance is underscored by ABI Research, which in its recent report “Mobile Networks Go Green” said there are significant opportunities for alternative energy specialists to sell to wireless suppliers. “Whenever you see the vendors pushing something, it’s usually because they’re being pushed by the carriers. And all of the vendors are pushing this heavily,” said ABI Analyst Nadine Manjaro.

Roughly 70% of a typical cell site’s power consumption goes to the base stations which can easily pull several kilowatts, largely because of mobile data services that require more bandwidth than simple voice calls. “The base station does consume a lot of power. There’s a drive toward reducing energy costs. At the same time, there’s also a requirement to improve the availability,” said Khurram Sheikh, chief product and development office at Powerwave Technologies. “It’s important that we have redundant power available at these locations. You could say they’re conflicting trends but they are trends happening in the industry.”

Holman: Alcatel-Lucent researches solar power on behalf of carriers.

For Powerwave’s lines of antennas and repeaters, “We’ve got a number of different ideas on how to attack it. We’re trying to become 20% more efficient in terms of power consumption. I think in the next 12 months it’ll go toward that,” he said. The company is also working on reducing power draw by adding intelligence to its network management software. Powerwave announced software last fall called NetWay, and has other software still under development called MaxCOM, that helps carriers like AT&T tune its base stations by remote control including the ability to power down certain functions when there’s reduced demand.

Similarly, to reduce power demands of the actual hardware, Alcatel Lucent works in five areas explained in a recent white paper, said Susan Holman, director of environmental health, safety and training for CDMA products. The research is in hardware integration and high-efficiency power amplifiers, software management, cooling from ambient air, use of fewer cables and reduction of sites needed for equal capacity. All products in Lucent’s wireless hardware families can be affected, she said.

Powerwave hopes to use software to increase energy efficiency and reduce technician visits.

This kind of research is useful for developed and underdeveloped nations alike. Sometimes the best test is to use new energy methods as production power in underdeveloped nations and for remote sites. Holman said Lucent uses solar power for 200 sites located mostly in equatorial regions around the world, while at Motorola, officials last year announced tests of solar and wind power for mobile networks in the central Namibia tourism village of Dordabis.

There aren’t yet any Tier 1 customers for solar base stations in North America, said Lucent’s Holman. But several carriers expressed interest in the feasibility and most want to be kept up-to-date, she said. “As the cost of energy increases, there’s certainly a focus on how to reduce opex costs. I think total cost of ownership is the key driver without question,” in addition to sending a positive environmental message,” she said.

FUEL CELLS
Still others prefer fuel cells. “There seems to be a lot of emergency power work going on … in the last 6-8 months, one of our clients has elected to use fuel cells in lieu of typical diesel power emergency generators,” said Bob Duclos, service group manager at cell site designer C&S Companies. That’s only in a few locations with tight space requirements but it makes for a healthy technology test.

Duclos: Fuel cells are the next big thing in base station backup power.

Fuel cells cost slightly more than generators, but the price is coming down, and there are fewer maintenance concerns, he said. Another fuel cell advocate is Anil Trehan, CTO of carrier solutions for the Andrew Wireless Solutions division of CommScope. Generators often connect to tanks of a 50-250 gallons of fuel to supply power not just for network equipment but also for cooling, so they need to run for 15-30 minutes every week as a precaution. That can be controlled remotely or by timers but technicians still need to visit for costly refueling, he said.

Despite different approaches to base station efficiency and alternative sources of backup power, all vendors and carriers agree on a pair of core facts – that in tough economic times it’s important to reduce energy use and that mobile communications are of national importance during emergencies. It remains to be seen which approaches will become commonplace and which will remain as niche applications. But this is a rare kind of industry debate in which everyone wins.