The Complete DAS Guide Active vs. Passive, Installation, and Recommendations.

In a wireless world, poor wifi & cellular signal is more than about convenience. Like electricity, plumbing and refrigeration, it’s now a modern necessity for us to connect to literally everything.

From phone calls, instant messaging, emails, high-speed data, streaming apps, and internet, any disruption can affect workflow, critical information, and professional reliability.

Think about the effects of poor cellular signal at home or work and the myriad of problems and helplessness that come with poor cell coverage & reception. Multiply that by the hundreds to thousands of people at a busy workplace or commercial venue… that’s a lot of inefficiency and thousands of lost hours.

When it comes to wireless solutions: broadband landline internet & cellular 3G & 4G (and soon to be 5G) internet are the two biggest technologies used to connect to the web & cloud.

While wifi from landline internet is the prevalent go-to technology in homes & offices, there are certain limitations, especially with the influx of wireless users, changes in wireless device habits, and the evolution of cellular technology.

Limitation 1.
Lack of Personal Security.

Wifi from landline internet has less security and more potential privacy issues with data being monitored by the employer/host at workplaces and other unsecured commercial or public areas.

Limitation 2.
Slow Download & Upload speeds.

In commercial high-traffic areas like hotels, airports, and stadiums, the building operator often pays for the lowest data speed plan available. When multiplied by the hundreds to thousands of users and cellular devices on the same network, it’s common to have very slow internet speeds.

With a lack of personal security and lesser download & upload speeds, many building operators are opting to use cellular connectivity to assist, complement, or even supplant their wifi landline internet. And with the upcoming promise of 5G and aggressive carrier competition to keep their unlimited data plans at low prices, there’s mounting evidence that supports of a cord-cutting generational shift.


21st century problems depend on 21st century solutions.
That’s where a DAS system comes into play.

DAS: Distributed Antenna System

DAS is a system of antennas that improve cellular & other radio frequencies for better coverage and more reliable service. There two main types of DAS known as iDAS (indoors) and oDAS (outdoors). However, a vast majority of DAS installations are in-building. And the two most popular indoor DAS solutions are known as Active DAS & Passive DAS. These two DAS systems are now being deployed across the country in many buildings by SMBs and enterprises to boost cellular signal strength to maintain workplace efficiency.

What’s the Difference Between Active & Passive DAS?

Both Active and Passive DAS have the same objective to improve indoor coverage; however, several major differences separate the two systems and therefore creates a different set of pros & cons for both active & passive DAS systems.

In general all DAS systems come with 3 main parts:

1. Signal source
2. Central processing point
3. Distribution unit

Active DAS

Active DAS provides boosted 3G & 4G LTE cellular coverage for buildings over 500K sq. ft.
Recommended for much larger venue over 500,000 sq ft. when strong signal is needed for almost 95-99% of entire area.

ACTIVE DAS ADVANTAGES
Most powerful cellular boosting solution.

The signal on Active DAS is often best-in-class in terms of signal boosting coverage range. Any high-traffic building over 500,000 sq. ft. needing complete wall-to-wall coverage (like a stadium or airport) should consider Active DAS.

Coverage area is virtually limitless.

The signal source for Active DAS comes directly from the carrier networks. Those signals are then converted from an analog radio frequency to a digital signal to maintain signal strength regardless of cable run and coverage area. Getting signal directly from the carrier base station resembles something like having a mini-cell tower inside the building.

1. Signal Source 2. Base Station (BTS, Node B, eNode B) 3. In-Building distribution (antennas)
THINGS TO CONSIDER
Much more expensive than other solutions.

Typically, Active DAS solutions average about $5-10 per square feet of coverage. So a 50,000 sq. ft. building could expect costs from $250,000 to $500,000 dollars for a complete Active DAS installation including product and installation service fees. A specialized equipment & cabling (fiber optic cables) are needed to re-convert digital signal to radio frequency for the area in need of coverage. While this adds to the performance, it also adds to the cost.

Longer deployment time.

Permission to connect to the carrier network is often a long bureaucratic process involving paperwork, budgeting, and lengthy time delays. And that’s only for one carrier. For each additional carrier, the same process has to be repeated. Active DAS installation can take several months up to a year.

REPUTABLE ACTIVE DAS MANUFACTURERS:

Passive DAS

Provides boosted 3G & 4G LTE cellular coverage up to 100,000 sq ft, although with multiple units, it’s able to cover up to 500,000 sq ft. Recommended for buildings at 10,000 up to 500,000 sq ft (with multiple units) with spot coverage for priority areas.

PASSIVE DAS ADVANTAGES
Inexpensive option for cellular coverage.

The signal on Passive DAS is often the best in terms of economical value since it is significantly cheaper than Active DAS. Typically, Passive DAS solutions average about $0.50-$1 per square feet of coverage. As a general rule, any building up to 500,000 sq ft needing only spot coverage (possibly with multiple units) should consider Passive DAS.

Faster deploy time (weeks compared to months).

A 50,000 sq. ft. building could expect costs from $25,000 to $50,000 dollars for a complete Passive DAS installation including product and installation service fees. Installation ranges from days to weeks to a few months.

1. Signal Source (donor or outside antenna) 2. Signal Booster 3. In-Building distribution (antennas)
THINGS TO CONSIDER
Dependent on having strong outside signal.

The signal source for Passive DAS comes from amplifying cellular signal to and from the carrier cell towers. Passive DAS (also known as bi-directional amplifiers or cell phone signal boosters) are highly dependent on having a decent outside signal from the cell tower to work. Generally, this is ok for most cases in urban areas. However, rural areas will need stronger amplifiers & antennas to achieve any significant boost.

Spot coverage for main areas instead of whole building coverage.

A whole building coverage and a contingency of having adequate outside signal are limiting factors.

REPUTABLE PASSIVE DAS MANUFACTURERS:

Which DAS Is Right For You?

of all commercial buildings in America are under 25,000 sq. ft.
of all commercial buildings are under 50,000 sq. ft. or less.
Of commercial buildings are large, high-traffic areas over 500,000 sq. ft.
Active DAS

Active DAS is best for large commercial buildings: complex, sprawling high-traffic areas like airports, stadiums, convention centers, and structures over 500,000 sq ft. For bigger & more populated areas in need of wall-to-wall signal, Active DAS is the preferred choice.

Passive DAS

Passive DAS is the best choice for buildings up to 100,000 sq. ft., with capability of scaling up to 500,000 sq. ft. It provides signal coverage when priority areas are more important than wall-to-wall coverage. Passive is 10-25% more cost-effective compared to Active DAS.

Things to Know Before Investing in a DAS System.

1
Causes of Poor Cellular & RF Signal

Cell phone signal is basically a radio frequency. Like most radio frequencies, cellular signal is fickle and can easily be redirected, absorbed, and blocked by literally everything under the sun. Let’s look at some of the biggest causes of weak cellular signal.

Distance between the cell tower and your building.
External Impediments (mountains, valleys, trees, structures, and weather).
Types & sizes of building materials that block, alter, or absorb cellular frequency.
Internal Impediments (drywall, plaster, wood, walls, and electrical or magnetic appliances.).

2
Forget the Bars: Understanding dB Gain

Most cellular signals operate with the 700 to 2100 Mhz frequency grouped into 5 bands we know as LTE, Cellular, AWS, and PCS. That level of signal strength is measured in dB (decibels).
-50 dB is considered strong signal, what most users would call full bars. -120 dB is poor signal, almost a dead zone. This is universally true for all cellular devices.

However, it’s up to the carriers to subjectively match dB readings to the number of bars on their own networks. This means what are 2 bars on T-Mobile could be 3 bars on Sprint or full bars on Verizon despite receiving the exact same signal and performing at the same speeds.

That’s why being able to read dB for all carriers is important to gauge true cellular signal strength.


3
DAS Components
Signal Source
Central Amplification Unit
In Building Distribution
Cables

SIGNAL SOURCE

For Active DAS, the signal source comes directly from the carrier network.

For Passive DAS, the signal source comes from pulling in and amplifying signal from the carrier cell tower. An outside antenna known as the donor antenna is used to capture cellular signal. Typically, a donor antenna comes in two forms: omnidirectional & yagi antenna.

Omni-directional Antenna
An omni-directional antenna has a 360 degree throw range with a +2 to + 5 dB gain. It’s a multi-purpose antenna when needing to boost signal for multiple carriers and if carrier towers are within range.
Yagi Antenna
A yagi antenna has a 110 degree throw range with a +7 to +10 dB gain. It’s a specialized antenna when needing to boost a particular carrier and if the carrier tower is much further away.

It is possible with a use of splitter to use both antennas for all-around boost while focusing on a specific carrier.

CENTRAL AMPLIFICATION UNIT

For Active DAS
The central amplifier is called the base station (also called BTS, NodeB, and eNode B).
For Passive DAS
The central amplifier is simply called the amplifier (also called repeater and signal booster).

Signal is passed to the amplifier where it is multiplied then passed along to the in-building distribution. Most Passive DAS amplifiers are capable of +60 to +70 dB gain.

IN-BUILDING DISTRIBUTION

Both DAS systems use indoor antennas to broadcast the boosted signal. Typically, broadcasting antennas come in two types: dome & panel antenna.

Dome Antenna
A dome antenna has a 360 degree throw with a broadcasting range of 50 feet. It’s a multi-purpose indoor antenna when needing to broadcast signal evenly across the open office.
Panel Antenna
A panel antenna has a 70 degree throw with a broadcasting range of 75 feet. It’s a specialized indoor antenna for priority areas, high ceilings, and corridors. They can be hid behind drywalls for aesthetic reasons.

CABLES

For Active DAS
fiber optic and ethernet cables are generally used.
For Passive DAS
LMR400 up to 100 ft, LMR600 up to 200 ft, and AL4 up to 400 ft.

Deployment Process of In-Building Wireless Cellular Systems

1. Assessment
  • Pre-survey
  • Site survey
2. System Design
  • Data analysis
  • Floor plans
  • Equipment & Pricing
3. Installation
  • Installing equipment & antennas
  • Optimization
4. Support
  • Documentation
  • Monitoring & support

Contact a DAS or Signal Boosting Solutions Expert.

Cellular boosting needs a thorough and fine touch. Our in-house cellular technicians are able to solve any unique problem with the best technology and prices.

From free consultation to post installation support, we provide end-to-end service. Contact us today and see how our wireless experts can provide instant answers.

Request Free Consultation.
Talk to one of our DAS or Signal Boosting Solutions Experts: 1-800-969-8189 (Mo-Fri 8AM-6PM CST)

At Signal Boosters, our team consists of industry telecom veterans who have formerly worked at AT&T and Sprint as well as some of the most skiller system integration teams across America.

Our motto: Provide solutions, not boxes.

This means we keep our service brand-agnostic with no upsells and sales jargon. We serve our clients 110% of the time, period.

If you have any questions or comments about improving your wireless in-building signal, we'll be honored to help, and share our insights to enhance your experience.