Over the past 20 years, Distributed Antenna Systems (DAS) have become an integral part of large building infrastructure. In fact, many US jurisdictions now require DAS installation in new and renovated buildings.
If you want cell phones, emergency responders’ radios, and other wireless devices to work flawlessly in your building, consider installing a DAS. This 2018 guide to distributed antenna systems will help you understand the most common types of DAS and effective implementation methods.
How a DAS Works
Simply put, a DAS is a network of antennas that transmit and receive cellular signals. This efficient distribution method circumvents steel columns and concrete that usually interfere with wireless signals.
In its simplest form, a DAS has two components: a signal source and a distribution system. The goal of these components is to provide ample coverage and capacity. Coverage is most important for buildings located far away from cell towers or constructed with materials that block cell signals. Capacity is the highest priority for locations that use significant cellular data, such as stadiums and venues that accommodate large crowds.
A DAS must be fed a cellular signal from somewhere. The methods for doing this include:
- Off-air: An antenna on the roof picks up signals from a cell tower. This is the most popular and cost-effective signal source. It’s feasible as long as the donor signal is strong and clear.
- Base Transceiver Station: A BTS signal source connects cell carriers directly to the core network via a fiber connection (usually installed by the carrier itself) for high-capacity performance. The setup time is long, but the results are ideal for highly populated venues.
- Small cells: The latest and fastest-growing signal source technology creates a secure tunnel to the carrier’s network over an Internet connection, generating a high-quality wireless signal.
Signal Distribution Systems
There are four ways to amplify, distribute, and rebroadcast a signal source through a building:
- Passive DAS: Coaxial cables, splitters, couplers, and taps passively distribute the wireless signal between indoor antennas. This is the lowest-cost option, but signal attenuation is a concern.
- Active DAS: A master unit performs an analog-to-digital conversion, fiber optic or Ethernet cables (CAT5e or higher) transmit the signal to active antennas, and remote radio units (RRUs) convert the signal back to analog.
- Hybrid DAS: Both fiber optic and coaxial cables distribute the signal throughout the building. Fewer RRUs are required, so a hybrid DAS costs less than an active system.
- Digital DAS: The latest technology allows a base band unit (BBU) to communicate directly with the master unit without analog conversion required. While theoretically simpler and cheaper to deploy, competing standards have resulted in little real-world use.
The most common ways to combine a signal source and signal distribution system include:
- Passive off-air DAS: Benefits include low cost, fast deployment, and multi-carrier coverage. A suitable outdoor signal is required.
- Small cell-fed passive DAS: Poor donor signal strength or congested towers make small cells a great option. A reliable backhaul Internet connection is required.
- Off-air hybrid DAS: Combine the abilities of an active DAS with the cost benefits of a passive system, ideal for large yet sparsely populated coverage areas.
- BTS-fed active/hybrid DAS: When the goal is capacity rather than coverage, have the carrier hook into your DAS system with a dedicated fiber connection.
Improve Wireless Coverage with a DAS in Your Southwest Business
For more information about designing and implementing a distributed antenna system in your building, please contact Corporate Technology Solutions. With headquarters in Phoenix, and Tucson, we have the capacity to serve businesses throughout the Southwest.