Lefebvre estimated there are roughly 10,000 outdoor DAS nodes, or site deployments, in the United States. Recently, NextG said it crossed the 5,000 deployment mark. And the market for indoor DAS, or in-building wireless deployments, is even larger. John Spindler, ADC's vice president of product management, cited a recent ABI Research report predicting 89,000 indoor DAS deployments worldwide this year.
Shuaib Porjosh, Sprint Nextel's director of radio frequency engineering, said he thinks more carriers are turning to DAS "just because the solutions are becoming more surgical."
When evaluating a possible DAS deployment, Porjosh said Sprint considers the location's geography and topography, the size of the area, and whether the company needs to build the system from scratch or can hop onto an existing, neutrally hosted DAS system.
Neutrally hosted DAS systems are analogous to tower sites that support multiple antennas for different carriers. Durcsak said the preponderance of outdoor DAS systems will be neutrally hosted sites. Porjosh said the estimate of 10,000 outdoor DAS nodes sounded accurate, and said Sprint has deployed roughly 1,500 such sites.
Verizon Wireless spokesman Tom Pica said the carrier uses DAS today to serve large customers where they need a better signal--such as arenas and airports. He said that when Verizon launches its LTE network, it will continue to use DAS in that way.
T-Mobile USA declined to comment on its use of DAS and an AT&T Mobility spokeswoman did not respond to requests for comment for this article.
For in-building coverage, Porjosh said Sprint generally leverages its relationship with a landlord to have a DAS system installed. For outdoor DAS systems--as with regular cell towers--carriers must get approval from local municipalities. In-Stat's Nogee noted carriers have been turning to DAS technologies as a way to overcome strict zoning requirements, since the antennas for outdoor DAS systems can be placed on telephone poles and lamp posts. Lefebvre said they can be hidden in street furniture or placed as a piece of fake cactus.
DAS is more expensive than putting in a regular base station, Nogee said. Cutrer of NextG conceded that installing a DAS system is initially pricey, but argued DAS can be effective if carriers look at total cost of ownership over the life of the contract.
"I really wouldn't say it's the preferred solution," said Michael Saperstein, PCIA's director of government affairs. "It's very expensive."
Cutrer said NextG can typically install an outdoor DAS system in nine to 12 months, but the timing largely depends on scoring leases from local municipalities.
"If the objectives are such that the economics don't make it worth it from [a return on investment] standpoint from the carriers' perspective, they'll walk away," PCIA's Durcsak said.
Despite the difficulties, DAS is coming to be viewed as a key element of network deployment for carriers.
"We're definitely seeing an uptick," Sprint's Porjosh said. "And I think the more the networks mature, DAS becomes a more and more important tool in the toolbox."