As Wireless Carriers Rethink Network Designs, Distributed Antennas Could Yield Big Gains

With mobile bandwidth demand soaring, the telecom industry is putting a lot of energy into rethinking wireless network design using small cells, Wi-Fi offload and other creative solutions. This creativity is even finding its way into the humble and often overlooked physical layer, as I learned at 4G World this week where I ran into a company called Solid Technologies.

Solid Technologies is a publicly traded Korean company established in 1996 with a specialty in base station repeaters and amplifiers, but has branched out into creating what it believes will be the next-generation of distributed antenna systems.

Traditionally those systems haven’t been much more than a cost of doing business for building owners. Without a DAS to enhance cell phone reception, a hotel, office building or convention center may have inadequate wireless coverage – and in today’s world that can really hurt business.

Solid Technologies’ concept is to turn the DAS into a revenue generator for building owners – and to provide even greater efficiencies for wireless carriers as they deploy new small cell infrastructure.

“DAS and optical transport are where we see the industry going,” says Mike Collado, director of marketing for Solid Technologies.

Distributed antenna systems traditionally have used a mixture of fiber and coax, with separate cabling pulled for each antenna head. And as Ken Sandfeld, vice president of sales for Solid Technologies explains, “If you put out an RFP for cellular and WiFi today, you get two separate systems.”

By going to 100 percent fiber augmented with 16- or 32-wavelength wideband WDM based on tunable lasers, Solid is positioning DAS systems to support multiple services over a single fiber, with separate wavelengths running to separate antenna heads or small cells.

The technology isn’t quite ready yet. As Solid CTO Saeed Anwar explains, if a DAS system will support 2G, 3G, 4G and Wi-Fi “we’re trying to make a seamless communications over those technologies.” Solid estimates that this will occur within 18 to 24 months because a range of manufacturers, including wireless equipment vendors, are working on it.

Once that capability is obtained, Solid envisions a range of new applications for DAS.

As Sandfeld explains, a next-generation DAS would be well positioned to support small cell deployments, providing the connectivity necessary to “granularize” one of today’s cells by a factor of 10. Because of the WDM functionality in the next-generation DAS, carriers will be able to lease just a single fiber from a dark fiber provider, where previously they would have needed multiple fibers. And by separating traffic from multiple small cells using WDM rather than virtual LANs, each small cell has more room to grow – and service providers may be able to delay the costly upgrade from a gigabit to a 10-gigabit connection.

“Optical technology is highly efficient for small cells,” notes Anwar. “You can go 60 kilometers on a single strand.”

Solid also sees a great opportunity for using next-generation DAS to support Wi-Fi offload infrastructure in stadiums, convention centers and the like. Anwar notes that a football stadium today may require as many as 20 base stations per wireless carrier to support fans’ cellular bandwidth requirements – and as more and more people use smartphones, bandwidth requirements will explode even further. As an alternative to more cellular infrastructure, Solid envisions that stadiums will use a next-generation DAS to support Wi-Fi infrastructure that can offload traffic from the cellular networks, potentially creating a new revenue source for the team.

Potentially, the same infrastructure also could be used to deliver some interesting new capabilities, such as a locally-stored instant replay feed delivered directly from the stadium to smartphone users without counting toward the users’ monthly mobile data allotment.

Ultimately, Solid also envisions that the next-generation DAS could also support a fiber LAN, ushering in the way for long-awaited fiber to the desktop.

“DAS is changing,” says Sandfeld. “It’s no longer just a piece of cable. It’s a network.”

He hastens to add, though, that “This is a DAS solution plus LAN. We’re not a Cisco competitor.”