by David Hartin, VP of Engineering
Connectivity Wireless Solutions
What is a DAS?
At a basic level, a distributed antenna system is like a repeater. It takes the wireless signal from the outdoor base station and repeats it, or extends it, indoors to a given area or throughout the entire building. As a building owner, you can extend the signal to several floors or a wing of your building or campus, or throughout the entire building or campus.
In truth, a DAS is much more sophisticated. With a standard in-building DAS, the cellular source, such as a wireless base station provides the wireless signal to the building through an antenna or wired landline connection. In the building itself, the DAS system consists of head-end equipment, bi-directional amplifiers, fiber distribution remote units, and in-building antenna access points, all connected through coax and fiber cabling.
The head-end equipment receives the signal from the base station and converts the RF signals to digital pulse signals. The digital signals are then distributed via fiber cabling to a network of fiber remote units and antenna access points that are located throughout the building. These antennas receive and radiate the RF signals to provide reliable wireless coverage.
What types of DAS are there?
Building owners may want to be selective about the type of DAS system they choose. A single-carrier DAS supports voice and data devices from only one service provider while a multi-carrier DAS supports service from multiple providers. As you can imagine, since most people working in or visiting a building will be carrying cell phones from various providers, it may behoove you to invest in a DAS that supports service from multiple carriers.
Historically, Distributed Antenna Systems were deployed by individual carriers who wanted to extend their service into buildings. More recently, neutral-host DAS are becoming more popular for a number of reasons. A neutral-host DAS means the DAS is owned by a neutral host (i.e., a building owner) that is not a carrier, since carriers typically have their own interests in mind and, therefore, are not neutral.
Now, the tables have turned and building owners are becoming more stringent in their requirements. They’re finding that multiple wireless technologies from various carriers can be supported with a single DAS, including CDMA, GSM, iDEN, LTE, PCS and WiMax. In addition, a public safety wireless network can be accommodated on the same DAS.
Who is using DAS?
You’d be surprised to hear how many buildings have a DAS. The indoor wireless issue is so pervasive it’s applicable to virtually any commercial building anywhere. Because of the demand for wireless services, commercial building owners are seeing more requests (or more complaints) from tenants and visitors alike.
In the hospitality industry, road warriors are becoming selective about which hotels and resorts they frequent based on wireless availability. Hotels understand how difficult it can be to gain a customer, so losing customer loyalty and repeat business is a hard hit to the bottom line. That’s why major chains like Hilton, Marriott, Starwood and others are implementing DAS to ensure they stay competitive and provide mobile services as an amenity, not to mention to improve collaboration between their own staff.
In hospitals, wireless technology helps improve quality of care and physician and staff productivity. The use of wireless devices is increasingly popular for ease of use, mobility and speed to market. For example, wireless telemetry devices are being used to monitor patient physiological parameters (e.g., cardiac signals) over a distance via radio-frequency (RF) communications between a transmitter worn by the patient and a central monitoring station. These advancements in technology are making it quicker and easier for physicians to monitor and coordinate care, while ultimately improving the quality of care delivered to the patient. As more healthcare applications are delivered via wireless, the need for reliable wireless becomes a critical component for the buildings on campus.
And on the university campus, wireless demand is in full force. Each new generation draws a flood of new wireless consumers who depend heavily on their wireless devices to stay connected to professors, family and friends. University campuses are deploying campus-wide DAS to keep their professors, staff and students connected. Mobile apps are popping up to keep students informed of class schedules and due dates, collaboration tools, and events. They’re also heavy users of social media.
The key factor is popuilation density. High-traffic areas where people congregate include public venues or mixed-use environments such as airports, train stations, athletic stadiums, convention centers and malls.
Basically, any indoor building or facility that draws the masses is a good candidate for a DAS.