DAS Systems 101

Commercial buildings are highly susceptible to poor cell coverage and interestingly, the more energy efficient a building is, the worse its cell coverage is likely to be inside. That’s because the building materials, especially the green ones like low-e glass, don’t allow cell signal to penetrate the walls or windows.

That’s where DAS — Distributed Antenna Systems — come in. These in-building systems are engineered to provide better cellular coverage for virtually any commercial building including commercial offices, multi-family, healthcare, K-12, hotels/hospitality, higher-ed or government.

DAS provides the cell coverage that is used for dozens of purposes but the two main uses are:

DAS for Public Safety and First Responders Cellular Networks

• Most commercial properties will require at least one DAS system to provide coverage for first responders’ two-way handheld communications. (These are also called Life Safety DAS, BDAs, Emergency Radio Responder Coverage, or ERRC for short.) Coverage must be provided for ALL first responders as well as mutual aid jurisdictions. Standards for these systems are based on NFPA and IFC guidelines, but individually enforced by the fire marshall and AHJ. Coverage requirements can vary, but in most cases 95%-99% coverage is needed throughout the building with special attention to emergency exit areas. Public Safety DAS is typically a requirement for all new construction, as well as any building that undergoes a significant renovation.

DAS for Voice/Data/Text Cellular Networks

• This DAS provides the cell coverage for the rest of us. Phone calls, texts, data streaming — all the magical things your phones and tablets do — rely on having a strong, dependable cellular network.
• Since 9/11, virtually all municipalities require the DAS that provides voice/data/text to be its own separate system from the Life/Safety DAS so that fire fighters and police are guaranteed reliable communications in the event of an emergency.

A myriad of technologies and manufacturers support cell coverage systems but there are basically only two main distinctions to consider:

Active DAS

Active DAS means you have to go out and ‘actively’ capture the cell signal through a hardwired fiber connection from each carrier’s network (i.e. AT&T, Verizon, Sprint, T-Mobile) to your antenna. The signal is then fed throughout the entire building via hardwired amplifiers and domes.

Active DAS Pros

• These systems can provide extremely strong cellular environments and are often preferred for LifeSafety.
• Active DAS systems can actually ADD carrier service when there is none available or it is insufficient.

Active DAS Cons

• These systems require a separate fiber connection to every carrier’s nearest tower.
• The building’s ownership must enter into a separate legal contract with each of the four providers; contracts are renegotiated every few years. Contractors and building management will need to allow sufficient time in the construction schedule to accommodate this process; generally 12 to 18 months.

Passive DAS

Passive DAS means a small antenna (about the size of a Pringles can) ‘passively’ (wirelessly) captures all of the available cell signal from all of the carriers. Just like an active DAS, it then feeds the signal throughout the entire building via hardwired amplifiers and domes.

Passive DAS Pros

• Passive DAS are carrier-compliant, FCC pre-approved, auto-attenuating and do not violate the FCC’s rules about over-amplifying one carrier’s signal versus another.
• Passive DAS systems are agnostic, meaning they capture and distribute all carrier’s signals equally.
• These systems incur no ongoing contracts or expenses for the building.
• Passive systems are more cost-effective, usually about 1/3 the price of an active DAS.
• Passive DAS can be deployed immediately, no waiting for carrier-approved contracts.
• Passive DAS systems can more easily be retrofitted.

Passive DAS Cons

• Passive DAS systems do not create cell signal, they merely capture the signal that is already available outside the building, then bring it inside and repeat it throughout the building as needed. Therefore, if there is no signal outside, the only solution is an active DAS system.

Understanding Your Needs

How do you know whether you need active or passive DAS? Do you even need a system at all? That depends on your property and how much cell coverage you currently have, if any. Testing to determine this is crucial and should ALWAYS be included in the SOW for new construction or renovation. For both cellular and Public Safety DAS, testing hardware and software are used to define, plot, and diagnose where coverage is sufficient or lacking. A good testing company will provide mapping of the building, identifying weak areas and then use this map to design your solution. PLEASE NOTE: Testing should be done when some exterior glass is in, but ideally, before drywall begins.

Once your site has been surveyed and the data analyzed, your cellular enhancement integrator can recommend either an active or a passive DAS. In general, if you can maintain a solid phone call outside your building, you can probably choose a passive system.

However, if you see the dreaded “No Service” icon on your phone when standing outside your building, you’re probably going to need an active system to bring service inside your building. An active DAS system is primarily used when a site has little to no cell signal available outside.

Illuminati Labs will help you assess the property’s size and extent of coverage needed, determine a sensible budget, clarify all of the options for enhancing your property’s cell phone coverage and then install your system in an aesthetically pleasing way with minimal disturbance to guests/residents/tenants. We will analyze and measure your current reception from every angle, review your needs and help you get the most boost for your buck.