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Distributed Antenna Systems (DAS): Guide for Installers & End-Users

Jun 12, 2019

Distributed Antenna Systems (DAS): Guide for Installers & End-Users

The role of Distributed Antenna Systems (DAS) in improving cell connectivity issues is paramount. It hasn't taken long for North America to become dependent on their devices. With this dependence has come increasing frustration caused by dropped calls, weak cell phone signals, and other connectivity issues. Businesses and individuals alike can all agree on the unprecedented levels of anger and annoyance that come from not being able to get online when they need to.

Luckily, as cell phone and tablet technology has evolved, so too has technology designed to keep everyone connected. Hello, SignalBooster.com. While there may be a few different solutions on the market, it is Distributed Antenna Systems (DAS) that are leading the market in solving problems with cell phone connectivity.

DAS technology effectively addresses poor connectivity issues in spaces of any size, from the smallest apartment through to the largest office building or stadium. There still exists a misconception that DAS technology is only useful in large spaces, but this couldn't be further from the truth. In fact, nine out of ten DAS systems are set up in relatively small spaces like apartments, family homes, and one or two-room office premises with our small to large size home office phone booster kits. Some require signal coverage enhancement over 10,000 sq. ft. with our commercial phone booster kits. DAS cost varies greatly depending upon the square footage that needs wireless enhancement, the strength of signal outside building, and the number of carrier networks that need to be densified indoors.

How To Choose the Best DAS System for Your Circumstances.

DAS technology comes in four forms: digital, hybrid, passive, and active. Those people with relatively low capacity needs can use above-stated wireless solutions (with link to products) to solve the connectivity issues within their home or business space. However, for large commercial users, the decision tends to come down to one between active or passive DAS. In most institutions, it is the system integrator who has the task of deciding whether active or passive DAS is the most appropriate solution for the individual circumstances at hand.

In general, integrators don't have any problem understanding the difference between active and passive DAS. However, they often find it difficult to effectively explain to their clients the differences between the two solutions and why one might be a better fit in certain circumstances. Read on to understand the difference between passive and active DAS, to hopefully give you the ability to explain the difference to your clients and to help them understand why you have made the recommendations that you have.

Active DAS

Active DAS is easily the most infrastructure-intensive and robust solution for connectivity issues, providing high-capacity solutions to suit larger areas. The way active DAS works is to create a cell phone signal in order to provide better coverage. The signal is then distributed between remote nodes that are strategically positioned within the premises and a signal source in a central location. As such, active DAS solutions are most effective in extremely large areas like arenas and airports, where thousands of people rely on connectivity within a relatively confined space.

Given these benefits, active DAS is usually the go-to solution for users and integrators alike. But that doesn't mean that active DAS technology is always the right choice for every situation. While it does have its strengths, the installation process itself is both invasive and complex. Fiber-optic cable needs to be installed inside walls, which can mean extensive access to structures and wall cavities. A dedicated backhaul is also required to be constructed, all of which can mean significant capital and time investments to install active DAS technology.

In fact, some active DAS setups can take more than 12 months to install at a cost of millions of dollars. As a quick gauge of the cost of an active DAS installation, clients will be looking at costs between $2 and $4 each square foot for a single carrier set up, and up to $10 each square foot for a multicarrier active DAS solution. Of course, this doesn't include costs incurred in the ongoing maintenance and support fees required in respect of backhaul and the dedicated fiber-optic cabling. By way of explanation, the backhaul component of a network supplies links between small subnetworks and the primary core network. This is why a properly set-up active DAS installation requires physical infrastructure connecting these components.

Passive DAS

Passive DAS technology is also known as cell phone "signal booster" technology and solves problems of cellular connectivity by boosting existing signals as much as thirty two times using amplifiers and antennas. Unlike active DAS technology, creating a passive DAS solution does not necessitate an internal network to be created. When compared with active DAS, installation and hardware requirements mean faster installation with a much lower initial financial outlay.

Passive DAS solutions involve the installation of an outside or donor antenna located close to a window or directly on the roof, which brings in the outside signal. Inside, or broadcast antennas which can be directional panel or omnidirectional dome antennas are strategically placed on either the ceiling or interior wall to transmit the boosted cell phone signal to cell phones and other devices within the building. Coaxial cables are used to connect either type of antenna directly to the amplifier unit.

One of the benefits of choosing a passive DAS solution is that, in most instances, regulatory approval is not required since the technology already conforms to FCC regulations. As such, installation of a passive DAS system can take a few weeks at most, with some complete systems installed and fully operational in a matter of days.

Due to the reduced equipment requirements, lower regulation levels, and significantly less overheads than active DAS solutions, a passive DAS setup tends to be a much more financially viable choice, with costs of installation and hardware tending to range roughly between $0.30 and $0.70 each square foot depending upon location requirements.

Another benefit of a passive DAS set up is that it provides simultaneous support for multiple carriers. This means that regardless of whether users choose Sprint, Verizon, T Mobile, AT&T, or lesser-known carriers, everyone can benefit from the same levels of signal boosting at the same time.

Application of DAS to a Variety of Venues

It follows that, except for excessively large areas where thousands of people are confined within a restricted space like arenas and airports, passive DAS should not be discounted as a viable signal boosting option. More and more, passive DAS is being chosen by conference centers, theatres, and other event venues, as well as within whole industries like education, hospitality, hospitals, real estate, and retail, as an effective feasible solution to cell phone connectivity problems that can be installed fairly quickly, effectively, and at a lot lower cost.

Perhaps most importantly, a properly installed passive DAS system can be a literal lifesaver. When public safety teams and medical emergency personnel have access to a strong reliable cell phone network, they can make use of critical maps and other location services and can more effectively communicate with each other and with the outside world. Passive DAS is the solution of choice in many emergency vehicles, courthouses, firehouses, and police stations for these very reasons, with emergency personnel fully aware that a passive DAS system enhances public safety and provides efficient, safe life-saving operations.

A Site Survey: The Essential 1st Step to Improving Cellular Service

If you're an integrator, you would be fully aware of the differences between passive and active DAS. The problem then becomes explaining these differences to your clients in a way that they can properly understand. Hopefully, this will serve as your complete guide to explaining these differences to your clients and helping them understand your recommendations.

Once you, in consultation with your client, have made the all-important decision between passive and active DAS, the next step is to help your clients understand how important a site survey is. Using the following list of site survey best practices, you can help your client understand why it is necessary.

  • First, let your client know how important access to the roof will be for their site survey to be carried out. Stress the improved effectiveness of the site survey if full roof access is granted. It may be necessary to offer to communicate directly with the building owner to help your client get permission to give you access.
  • Next, make sure you familiarize yourself with the site by looking at the floor plan of the building. This will assist you in mapping potential signal areas while the site survey is being performed.
  • During the survey itself, begin on the roof. Using a survey kit with signal meter, place yourself at extreme ends of the building and make a note of the signal strength at each position, recording all frequencies and channels at each position.
  • Once you have located the optimum signal, stand in that position and rotate a full 360 degrees to locate the signal source. Once you have identified it, make a note of its direction. Doing so, will give you a very good idea of the location of the closest cell tower, and if engaged in the installation of a passive DAS system, it will give you the location and orientation for installation of the donor antenna.
  • Continue to make your way along every corridor and room in the building, noting fluctuations of signal strength based on your location.
  • Once you have completed the physical aspects of the site survey, use your notations about signal strength and the building's floor plan to create a strategy to place indoor server antennas in optimal positions to maximize indoor signal coverage. For many integrators, the most effective and easiest way of accomplishing this is to use software for network planning such an iBwave.

Above is your complete and simple guide to explaining active and passive DAS and the importance of a site survey to your clients. For a more detailed and technical description of DAS, please see the Ultimate Guide to Distributed Antenna Systems on our website.

Learn everything about DAS:

What is DAS?

DAS stands for Distributed Antenna System and is used to supply cellular signal within large buildings like convention centers, hospitals, schools, stadiums and so forth. Oftentimes, these buildings are made of concrete and metal which weaken or sometimes completely block the signal from passing through. So you may have decent cell signal outside the structure but once you go inside, you're unable to use your phone because of poor signal quality. I'm sure this has happened to all of us.

What does DAS do?

This is where a DAS system comes into play. The DAS takes the signal outside of the building, brings it inside and distributes that signal throughout the building. There are two main types of the DAS systems: Passive and Active. We will talk about these the pros and the cons as well as the best applications for each of these types of DAS.

What is Passive DAS?

Passive DAS, sometimes called cellular signal amplifiers, captures the outside cellular signal through the donor antenna and sends it through coax cable to the amplifier unit. If the signal is weak, the amplifier boosts the signal and then sends the stronger signal out to the network of broadcast antennas using splitters. Cellular amplifiers come in a range of sizes to cover anywhere from 5,000 to 100,000 square feet with a single amplifier. Multiple units can be connected to a single donor antenna if needed to provide larger coverage areas. These amplifier units can be located anywhere in the building from server rooms to data closets or anywhere else that it is required so you can cover nearly any size building using passive DAS.

What is Active DAS?

Active DAS works by passing that signal inside through coax cables from the carrier to a digital conversion unit inside the building. There, the signal is converted to an optical signal and is passed through fiber-optic cables to a remote access unit, or RAU elsewhere in the building. The RAU converts the signal back to RF and amplifies it and then distributes the signal through coax cables to the broadcast antennas all across the building.

Passive DAS Pros (Benefits and Advantages).

Passive DAS is much less expensive to deploy. It is normally about 75% less than the cost of active DAS. Passive DAS or cellular amplifiers provide coverage for all carriers and frequencies. Multiple amplifiers can be placed throughout the building to cover nearly any size building. Installation and implementation of passive DAS is less complicated because there is no conversion of signal required and less components involved.

Passive DAS Cons or Disadvantages.

Because the signal will degrade as more cable is introduced, it is not recommended to use long cable runs with a passive DAS. Instead, use multiple amplifiers throughout the structure to provide the needed coverage. For extremely large buildings like stadiums, passive DAS is often not a prime solution due to the need for long cable runs.

Active DAS Pros (Benefits and Advantages).

Converting RF to optical signal and using fiber-optic cable allows for very long runs with no signal loss. You can monitor an active DAS remotely via SNMP. Active DAS is suited for very large buildings because of their ability to run very long cable runs with no loss.

Active DAS Cons or Disadvantages.

Active DAS is very expensive to implement, often costing as much as 10 times that of passive DAS. Active DAS only works for one carrier's frequency. To implement a full solution for all carriers, multiple sets of the various components are required complicating installation and increasing cost. Implementation of active DAS is more complicated and involves many more components. It also requires a lot more time - months, or sometimes even years due to add'l approvals required by respective cellular service provider(s) and local Authority Having Jurisdiction (AHJ).

Summary.

In short, passive DAS is a great solution for most buildings like hospitals, retail stores, hotels, shopping malls and schools. You can provide identical coverage in these types of buildings at a fraction of the cost of active DAS. Active DAS is ideal for very large structures like convention centers and stadiums. It can be used in smaller buildings, but often the cost is prohibitive for these types of installations.


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4 comments

  • Okay, now I understand the whole active DAS vs. passive DAS conversation. Active DAS sounds fantastic, but it sounds like you can go with passive DAS in certain situations and save yourself a lot of money. If your budget is tight you can still get a strong signal in your facility by using passive DAS (unless that facility is a huge building or something like a stadium). If I’m reading this right, a passive distributed antenna system will work well in many situations, saving you some serious bucks.

    Amy Kaufman on
  • Distributed antenna systems (DAS) are one of the great innovations in cell phone boosters for office buildings, malls, and stadiums (along with other facilities). Wiring a facility so your cell phone signal is strong even in your building’s nooks and crannies is what a DAS is all about. You could be in the basement, the elevator or some other traditionally bad area to get a signal and a DAS delivers a strong signal. I hope these become as common as phones themselves.

    Johanna Stovroff on
  • This is an observation and not a judgment/endorsement but there seem to be many useful articles here for people whether it’s someone with your average cell phone, someone with a small business office, or something big like a factory or office building looking for more information about distributed antenna system design. The common denominator is poor cell signals and there are a surprising number of solutions.

    Erick Reed on
  • This blog could be called “DAS for dummies” (not that any of us are dummies) because it answered many of my questions about this tech. I thought DAS was just for big buildings so that myth was dispelled. I know public safety boosters for first responders are becoming mandatory and wish DAS boosters would be too. Anyone else think so?

    Eddie Miller on

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