Distributed antenna systems are gaining traction as an alternative way for service providers to fill in coverage or add more capacity to the wireless network when macro cellsites are not an option, as well as a way for smaller carriers trying to get to market quickly. However, these small antennas that usually sit on top of utility poles face their own challenges in an unsettled regulatory environment.
How they work
Outdoor DAS networks generally employ a group of smaller, line-of-sight antennas deployed on existing utility poles, which are at a lower height than traditional cell towers, and are connected through fiber at the pole that connects to a transceiver base station hub. The RF signal is transformed to an optical signal as it runs through the fiber to the hub, where it is again converted to an RF signal.
As a rule of thumb, it takes between three and five DAS nodes to equal the coverage carriers can get from one cellular macro site. DAS networks are generally more expensive to build than traditional cellular towers, said Gerard Ainsztein, senior VP of DAS Solutions at American Tower Corp., because they require more nodes to get the same amount of coverage. Plus, even though only a few utility poles hold DAS nodes, the tower company may have to run fiber through 10 times as many poles to reach the base station hub.
DAS solutions work in tandem with macro cellular tower builds, rather than compete with them. DAS networks are often used by service providers that cannot get siting permission for a traditional tower, for carriers that want better in-building coverage, or to expand capacity and coverage in a particular area. They are also used by carriers with less spectrum that want to get to market quickly like Leap Wireless International Inc. and MetroPCS Communications Inc.
Players in the space
Traditional tower companies, like American Tower, Crown Castle International Corp. and SBA Communications Corp., are playing in the space, as well as pure-play DAS providers like ExteNet Systems Inc., NextG Networks and NewPath Networks. Equipment providers like Andrew Corp. and ADC also offer DAS solutions. American Tower acquired its DAS business with the purchase of SpectraSite in 2005. SpectraSite had a lucrative in-building business that launched in 2001, and today American Tower counts about 200 owned and managed in-building DAS networks. Crown Castle got into the space about seven years ago, and turned on its first system in March 2004, said Rick Platt, VP of national sales at Crown Castle Solutions. The company started out offering outdoor solutions, but is also offering indoor solutions.
Growth ahead
DAS networks are well-suited for urban and suburban environments, particularly when it is difficult to get zoning approvals, said Pedro Miraz, director of DAS development and implementation at Crown Castle. Like their tower counterparts, DAS providers tend to build for multitenant solutions, with the DAS owner as the neutral host.
Many agree that as consumers continue to embrace smartphones, their applications and as 4G networks continue to be built, DAS solutions will continue to grow. DAS networks will contribute to 4G technology deployments because carriers will need higher data speeds, which mean shrinking cell sites. Backhaul requirements will also be greater with the need for more fiber-based solutions, said Ross Manire, founder, president and CEO of ExteNet. Indoor solutions will play prominently in 4G deployments because people use their devices inside and the indoor solution can offload capacity from the macro network. Even today, about 80% of calls are made from inside a building, Manire said. As consumers use more multimedia applications, like streaming video and social networking apps, people are probably going to use those entertainment apps inside rather than outside.
ExteNet, for example, recently installed an indoor system for Leap’s Cricket Communications Inc. division in Chicago’s McCormick Place convention center using existing HVAC infrastructure. ExteNet installed the wireless network using the heating, ventilation and air-conditioning metal duct work throughout the four buildings that make up McCormick Place’s convention center. “DAS won’t be the only solution, but it will be part of it,” Manire said.
Regulatory challenges
Of course, anytime someone is siting an antenna, regulatory issues are sure to follow.
Indoor DAS solutions don’t have too many regulatory issues as a company only needs to get a construction permit, said American Tower’s Ainsztein. The waters get a little muddier once DAS goes outside.
Ed Donohue, a principal with Donohue & Blue plc, a law firm that helps carriers and tower companies, as well as PCIA, with zoning and rights-of-way issues, said the laws around DAS networks are still evolving, “which sometimes makes it difficult for the DAS provider to know what to expect.”
In general, (and keep in mind that means generally; each jurisdiction is unique) telecom providers, including tower companies, can apply for a certification status as a kind of telecom carrier’s carrier, so to speak. In California, the term used is Certificate of Public Convenience and Necessity, or CPCN, Donohue explained. “It allows you a seat at the table.”
It also means utility companies generally have to allow the DAS provider access to the utility pole, and because the pole (generally) is in the right of way, it is exempt from zoning requirements, Donohue said. In reality, however, “that bright line is not so bright,” he noted. Leasing charges and other issues come into play. For example, DAS providers want to be on the top of the pole, and utilities sometimes try to charge DAS providers more than a cable provider would have to pay for space on the pole because they are at the top. Also, because utility companies don’t make huge amounts of money from letting others have access to their poles, they’re not always eager to accommodate the DAS provider because it’s not their core business. And if the pole needs to be modified to accommodate the weight of the new equipment, the DAS provider can be asked to pay for the cost of a new pole.
And while the antennas are fairly discreet, hub sites that can measure 25 feet by 25 feet are sometimes difficult to zone. “Sometimes jurisdictions have great ideas where the hub should go, but often it’s in the next town,” Donohue chuckled.
PCIA launched the DAS Forum in 2006, said Connie Durcsak, senior director, industry services, and executive director of the DAS Forum. The forum doesn’t take a position on whether macro cellsites or DAS networks should be deployed, but does work to make siting DAS networks easier when the solution is deployed. The forum works to educate municipalities about how DAS solutions work, advocates against barriers to entry as the systems get deployed and is working on a set of standard processes so the networks are generally built in a similar fashion so each time a network is deployed, companies don’t have to reinvent the wheel, Durcsak said.
