Mobile Infrastructure | Feature
Connecting the Dots in DAS
With the use of smartphones soaring, distributed antenna systems (DAS) offer schools a way to improve cellular service, even in the most problematic corners of campus.
The bad news from campus is that students are not sleeping alone. The good news? It's their phones they're cozying up to. Indeed, a recent survey from HackCollege indicated that 75 percent of college students sleep next to their phones. The finding is a stark reminder of just how reliant today's students are on their mobile devices, be they smartphones, tablets, or regular cellphones. In fact, many students consider reliable cell coverage as something akin to an inalienable right.
Surprisingly, even as schools push to deploy reliable WiFi networks, not all college campuses offer adequate cellular coverage. As students consume more content with their wireless devices, commercial wireless operators like Sprint, Verizon, and AT&T are under great pressure to handle the new data traffic. Uploading photos to Facebook and watching YouTube videos take up much more bandwidth than making a phone call. To help address the issue, many institutions implement a distributed antenna system (DAS) as part of a holistic approach to providing better wireless coverage and capacity on campus.
A DAS provides wireless service within a particular area or structure via a network of separate antenna nodes that are connected to a common source through fiber or coaxial cable. Because DAS antenna node installations are compact, they can be deployed either inside or outdoors. They are more expensive to deploy than macrocellular towers, however, so DAS networks are often used to augment coverage and address capacity constraints in a targeted area.
"Our goal is to find the most economical solution, which could include towers, rooftops, DAS and WiFi," says Mike Kavanagh, president of DAS sales for Crown Castle, the nation's largest neutral-host DAS provider.
Major phone companies do deploy DAS networks, but a university population usually carries plans from a wide variety of carriers. As a result, it may make sense to contract with a neutral-host DAS provider, which can then contract with multiple carriers to carry their signals.
WiFi technology remains the mainstay of the campus computing experience, and DAS is not intended as a replacement. While DAS can accommodate WiFi--and some companies sell solutions bundling the two--the results can be disappointing and costly. In addition, schools risk vendor lock-in that can be difficult and expensive to resolve.
WiFi does have some drawbacks, however. While WiFi networks are a good way to offer broadband connectivity and some mobility to students, they use unlicensed spectrum that can become overloaded from too many users, degrading the quality of the service.
One of the biggest differences between WiFi and cellular service involves emergency calls. WiFi was not designed to provide location information required when an emergency call is made to 911. For DAS vendors, this is a key selling point, especially since the Federal Communications Commission estimates that about 70 percent of 911 calls are made from cellphones.
"Parents want assurances that, in the event of an emergency, students can contact 911," says Seth Buechley, president of SOLiD, a provider of DAS and optical network solutions. "Similarly, they want to know that communications from first responders and school administrators--as well as their own--will get through."
Deploying a DAS Solution
For many institutions, the most economical way to obtain both coverage and capacity on campus is probably a hybrid approach that utilizes a variety of technologies, including DAS, other small cells, and even macrocellular towers. "Using a hybrid solution allows service providers to allocate capital to areas of the campus where a DAS is the only viable solution," says Gerard Ainsztein, senior VP of managed networks at American Tower, a nationwide neutral-host DAS provider.
Collaborative efforts among the university, wireless carriers, and neutral-host providers are needed to manage expectations among the parties involved. While a university may want the best possible service in every building and around campus, such a goal may be unrealistic, says Tormod Larsen, CTO of ExteNet Systems, a neutral-host provider that owns and operates distributed networks including DAS and other small-cell solutions. Larsen advises universities, wireless carriers, and neutral-host providers to set realistic goals and expectations about what services can be provided where and when.
DAS deployments on campus can be particularly tricky because there is a wide range of venues, as well as many constituencies with different goals. "Everything from historical societies to arborists' concerns could impact the proposed design, which is a bit outside the realm of engineering," notes Peter Murray, director of wireless solutions at CCI Systems, based in Michigan. "Technically, it often requires different DAS systems to solve the issues surrounding indoor deployments, outdoor coverage, and the capacity issues of stadiums and arenas." Successful deployments are often done in stages that can occur over the course of a few years.
Because a DAS is expensive to install, third-party providers and carriers prefer long contract terms--preferably 10 years--to justify their investment. "This allows both the neutral-host provider and the wireless-service providers to benefit from the DAS over an extended period and earn a reasonable return on their invested capital," explains Ainsztein. "The minimum 10-year term will also result in a higher of number of carriers that will utilize the DAS, which ultimately benefits the campus and the students."
Where's the Cash in DAS?
DAS deployments can require large upfront capital investments and be financed in a number of ways. There are three basic ownership models, but all require carrier approval:
- In a carrier-owned DAS, a wireless service provider pays for the equipment and installation costs, as well as any maintenance and upgrades. While often built for exclusive use, the operator may charge other operators to attach to the DAS.
- Building owners and managers are responsible for all the costs. In this scenario, it is important to get wireless service providers to approve the design and installation.
- A neutral-host third-party provider bears the costs of the DAS. In this scenario, the DAS company aims to get more than one wireless service provider on the network and split the costs among the service providers.
Universities can help bring down the cost of a DAS by contributing existing campus assets and resources such as fiber, space to house the DAS base-station hotel, and staff familiar with the existing IT infrastructure.
Before a school deploys a DAS, administrators should consider what additional services they might want to provide via the network. According to Ray Hild, director of channel sales at Corning MobileAccess, many colleges and universities use their DAS to add applications covering student safety, security, and event and transportation updates. Some schools even push courseware to wireless devices, while others use it to make money from third-party vendors by sharing revenues from apps designed for campus use or from advertising opportunities.
Tracy Ford is director of The DAS Forum, a membership body within PCIA, the Wireless Infrastructure Association.