CONTROLLING THE REMOTE

While the majority of cell site towers are typically located in populated, urban areas and along major roadways, wireless carriers chasing after ubiquitous coverage must often place sites in difficult-to-reach or inclement locations. Raising towers in urban environments has a set of engineering headaches all its own, but when cell sites are planted in remote desert regions, hurricane hotspots or on snow-capped mountains that can only be reached via all-terrain vehicles or helicopters, accessibility for repair and maintenance becomes a real problem.

Until just a few years ago, carriers were alerted to a battery problem at their sites only when they experienced a power outage. Recent advances in remote monitoring systems are working to alleviate many of the pains associated with out-of-the-way cell sites, and although maintenance teams still must physically visit cell sites in need of technical attention, problems can now be detected before they arise or specifically identified after they occur.

But despite advances, battery maintenance is a continuing problem that is often worse than environmental elements.

“The weakest link in the power infrastructure is the batteries,” said Paul O'Rourke, business development manager at American Power Conversion. “That's what creates the difficult environment.”

Emerson Network Power Group, the service arm of Emerson Energy Systems, supervises power equipment remotely with its computerized Energy Master system, available in both PC and UNIX versions. Emerson president Thomas Bjarnemark said that this fall the company will also unveil a complete energy management system that is capable of supervising and managing any power component in a telecom network, from power to air conditioners to backup diesel generators.

“Any equipment you have on site, we can supervise and manage it remotely,” Bjarnemark said, adding that remote monitoring also reduces spare part inventory. And because power systems operators know exactly which battery is waning, maintenance teams can take only those components they know they'll need, rather than dragging every conceivable component to a site because they don't know the nature of the problem.

Sprint PCS has cell towers and power equipment located at both ends of the hot/cold climate spectrum, from mountaintops in Colorado and bitter cold regions such as Minnesota to hot and humid areas such as Arizona and Florida. John Harrison, vice president of network operations at Sprint PCS, said the carrier's network operations control center monitors meteorological conditions 24-7 during hurricane and winter storm seasons. If a severe storm is spotted, Sprint deploys its Disaster Preparedness Team to track it and arrange for backup resources in that area. He also said that depending on the storm's magnitude, they often ready resources in other markets as well.

“If the storm is in Minneapolis, we may pull portable generators from markets as far away as Des Moines, Kansas City and St. Louis, put them behind trucks and drag them up there,” Harrison said.

Although Sprint's power equipment is exposed to the elements, many power supplies in harsh geographic areas reside in sturdy building enclosures that house power equipment, batteries and maintain internal environments with heating, ventilation and air conditioning systems.

But regardless of the conditions outside the enclosure, all power systems are designed to nearly identical specifications that use durable components that can survive in extreme conditions, O'Rourke said. Because companies such as APC don't always know where its equipment is headed, they engineer around the toughest climate scenarios.

“We'll have an agreement with a service provider to supply 400 systems, and all we know is that they're going to Southwestern Bell's territory — we don't know what is going to be in Arizona or Chicago,” O'Rourke said. “We tweak the configuration of our systems around requirements of our customers, but the basic fundamentals aren't changed.”

O'Rourke said that space concerns are fast becoming the most difficult problem and are driving the most change in network power. Wireless carriers that are planning to roll out their 2.5G and 3G networks are interested in using existing enclosures and fitting more power density into the same 12-by-12 ft. shelters. Although progress has been slow, O'Rourke said equipment providers are making power density headway.

“The equipment that we're deploying now is about 25% more dense than the previous generation, which is about 25% more dense than the generation before that,” he said. “The power guys have been very good about moving the window wider and wider over the last ten years, but what hasn't changed is the battery situation.”

Belleville, N.J.-based H Power is addressing battery life and density issues simultaneously. The company's EPAC product offers operators a hydrogen fuel cell power alternative to batteries. Paul McNeill, H Power's VP of business development, marketing and sales, said the power industry is increasingly moving toward fuel cells as carriers begin to show interest in using these systems as replacements for the lead acid batteries that have been used historically.

Because fuel cells create electricity, heat and water without emitting harmful emissions of any kind, they are a cleaner and therefore more environmentally friendly power source than traditional batteries, McNeill said. Fuel cells are also smaller, more compact devices that have higher energy density than traditional batteries and require very little maintenance. By using hydrogen as a power source, companies can spend fewer man-hours journeying up mountainsides to address battery-related issues.

H Power introduced its first units in 1998, building 55 devices that the New Jersey Department of Transportation used as battery chargers for roadside emergency lights. McNeill said that those units have been in the field for more than four years, and are still in use today.

The new EPAC product is currently being tested on a mountaintop in Wilkes-Barre, Penn., and in other remote areas such as Yellowstone National Park. (McNeill said H Power is in discussions with other carriers, but declined to name them.)

While EPAC's environmental benefits are certainly a selling point, McNeill said that despite its higher cost, EPAC is being marketed on economic rather than environmental grounds. Because the devices are engineered to last, they're more expensive to mass-produce and therefore sell at higher prices than other power sources. The cost savings, McNeill said, come later.

“When you're looking at a schedule for a diesel or petrol generator that requires somebody to go out and have a look at it every 200 or 300 hours vs. an EPAC, which can go 3000 or 4000 hours without any kind of maintenance, you're seeing a reduction in charges.”

Frank Albano, vice president of commercial power systems at Alpha Technologies, said that although fuel cells represent the future of battery backup, they aren't there yet. The significantly lower cost of using batteries vs. fuel cells and the impracticality of using pure hydrogen are both factors holding fuel cells back.

In the interim, Albano said photovoltaic cells are one possible alternative. The cells can be mounted on rooftops or power poles where they capture sunlight, which is converted into power for a battery system. In addition to using natural sunlight, Albano said the cells can also increase power density for power backup systems.

“Instead of using ground space you could increase it by attaching photovoltaic cells to your pole,” he said.

As other fuel cell technologies and more sophisticated remote monitoring capabilities continue to emerge, wireless carriers will be more confident about erecting cell towers in tough-to-reach locales because they'll have fewer maintenance concerns in those areas. And in the process, they'll be able to extend overall coverage and provide better service — especially to those who walk along the roads less traveled.

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