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With the continued increase in enterprise demand for cellular data and voice for mission-critical and day-to-day operations,

mobile operators are supplementing network capacity and coverage using small cell platforms or indoor DAS (iDAS), or through

the use of smart signal boosters that have been approved for use on their networks. Similarly, businesses that increasingly

rely on cellular service often take it upon themselves to search for solutions they hope will cost-effectively solve their cellular

connectivity problems. Yet, in many environments, available indoor coverage options are either too complex or too costly for

enterprises or service providers to consider.

Nextivity worked directly with global operators to create the Cel-Fi QUATRA In-Building Enterprise Cellular System, an

addition to the Cel-Fi family of products that is designed to resolve the in-building densification challenges of the middleprise

(i.e., venues up to 200,000 sq. ft.). QUATRA is an active DAS hybrid that combines the best of active DAS and the Cel-Fi

technologies that have been widely adopted by operators and enterprises around the world. The system is scalable for future

company expansion, and can be deployed in a matter of days by a certified installer at a compelling price.

At the date of this white paper, Cel-Fi QUATRA has been approved by the FCC and ETSI (CE), and is available for use on 22

global operator networks, including the top three in the United States.

Purpose and Intended AudienceThis paper provides an in-depth look at the Cel-Fi QUATRA In-Building Enterprise Cellular System for commercial in-building

cellular coverage, including how it works, and different use-case configurations. The paper is intended for mobile operators,

integrators, installers, and interested business or IT professionals that want to better understand this hybrid solution to solve

in-building cellular coverage problems for the underserved middleprise market.

By Joe Schmelzer, Senior Director of Products at Nextivity

Cel-Fi™ QUATRA In-Building Enterprise Cellular SystemUsage and Configurations: Off-Air and Supercell

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A New “Smart” Approach to Coverage In developing Cel-Fi QUATRA, Nextivity leveraged its proprietary processor technology and digital architecture that powers its

family of Cel-Fi cellular coverage solutions. The digital architecture that underlies these proven solutions provides both the

intelligence and scalability required to deliver and optimize indoor cellular coverage for the middleprise.

“Smart” refers to the intelligent architecture that self-configures and self-optimizes, making the qualified installer’s job easier.

The system intelligently adjusts and adapts to changes in the environment or network, eliminating interference and always

maximizing performance once installed. This reduces maintenance costs and alleviates the typical demands on staff to

maintain a traditional active or passive DAS.

The smart digital architecture includes many features such as: automatic gain control to maximize system power, uplink

power control to the macro network, advanced digital echo-cancellation and feedback control, uplink gating, and signal

qualification (channels are individually qualified for boosting, so noise or very poor signals won’t be amplified and won’t

degrade the network).

These smart systems have been designed in conjunction with operators to improve indoor coverage without the network

interference problems and installation complexity associated with other types of systems, like common bi-directional

amplifiers (BDA), repeaters, or traditional DAS. Cel-Fi QUATRA is proven to be unconditionally network safe, which ensures

there is no network interference, and can be deployed confidently.

In off-air mode, Cel-Fi QUATRA delivers up to 100dB gain, which is up to 1000x greater than competitive systems. More power

means a bigger coverage footprint with fewer components.

A typical Off-Air Gain “per-channel” power example.

COVER A DESK-90 dBm + 60 dB Gain yields: -30 dBm Booster Powercoverage:

COVER 1–2 ROOMS-90 dBm + 70 dB Gain yields: -20 dBm Booster Powercoverage :

FULL COVERAGE-90 dBm + 100 dB Gain yields: +10 dBm Booster Power coverage:

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Cel-Fi QUATRA In-Building Enterprise Cellular System Cel-Fi QUATRA is an active DAS hybrid. A single system which provides coverage up to 50,000 sq. ft. is comprised of one

Network Unit (NU), which is the head end or hub of the system; and up to four remote units that distribute and rebroadcast

the donor signal, called Coverage Units (CU). The CUs are powered antennas (thus the “active” in active DAS hybrid), and have

full transmit power available without suffering from coaxial distribution power loss. This provides a stronger cellular signal for

end users to carry out mission critical and day-to-day business operations from their cellular devices.

If the area to be covered is larger than 50K sq. ft., multiple Cel-Fi QUATRA systems can be installed. QUATRA can be deployed

within larger venues by installing up to four NUs, each connected to up to four CUs. In this scenario, by synchronizing the

outputs from multiple CUs, the coverage area of each CU is stitched together to form one large cell that can provide coverage

across an entire building of up to 200,000 sq. ft. Cel-Fi QUATRA may use either an (a) off-air or (b) small cell donor input,

depending on the specific coverage and capacity needs at the site.

A certified installer can use the Cel-Fi QUATRA Planner Tool prior to a site survey for automated configuration and output

of suggested network elements. This portal-based tool eliminates time-consuming manual calculations that integrators

generally need to do when initially designing an in-building solution. Instead, an estimate can be built from data supplied over

the phone or via email, before the site survey, to develop a preliminary bill of materials (BOM).

While a site survey is recommended, highly sophisticated and costly legacy design tools, like iBwave, are not required. The

integrator installs and maintains the system using the Cel-Fi WAVE platform, a cloud-based management interface with an

easy-to-use dashboard for system optimization, alerts and alarms, and software updates. Nextivity provides the QMT (QUATRA

Management Tool) smartphone app that enables Cel-Fi QUATRA systems to connect to the cloud through the phone’s data

connection, and Bluetooth, if an Ethernet LAN connection isn’t accessible.

Once the system is mounted appropriately, standard Cat 5e (or better) cable is used to connect the NU with each CU, eliminating

the need for costly fiber installation (many commercial buildings are already wired with this cabling, further reducing installation

costs). When powered on, all network and system optimizations are performed automatically. The built-in intelligence of the

system, coupled with the QMT, means that Cel-Fi QUATRA can be installed in a matter of days—considerably faster than other

enterprise solutions on the market.

Cel-Fi QUATRA Elements

COVERAGE UNITS (CU)• Up to four (4) per NU• Power over Ethernet• Built-in or external antennas• Horizontal ceiling or vertical wall

mountable• Mounting Kit included

NETWORK UNIT (NU)• Built-in or external donor antennas• Accepts Small Cell donor inputs

(to one or more QUATRA systems)• Powers entire system• Self-configuring• Mounting Kit included• Enterprise management

PSU

MIMOEXA

EXAMIMO

NETWORK UNIT 1NETWORK UNIT 2

MIMOMIMO

MAINMAIN

SCIF

NU

CU

CU

CU

CU

SMALLCELL

200 meter max with Extender

NU = Network Unit CU = Coverage Unit

100m

Donor Options

100m

100m

100m

Cat 5e or better

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Why an Active DAS Hybrid Solution is Better The combined capabilities of active DAS and the digital architecture of Nextivity’s smart, operator-class, indoor

coverage solutions eliminate problems associated with existing indoor cellular coverage technologies, offering the

following advantages:

• Much higher gain in off-air mode without overloading the network with amplified noise (capacity-killing interference)

• Larger coverage footprint per server antenna

• While building surveys are always recommended, expensive and cumbersome RF tools are not required for planning

or installation

• Dynamically tunes to operator network frequencies

• Makes the network more efficient (a better signal means the same amount of data may be transmitted in less time

with less energy, freeing up network resources for other users)

• System management options available for enterprises that want to implement alarms and alerts

• Scalable for future expansion without the need to re-engineer

Driving Down Cost and Complexity for the MiddlepriseA large enterprise may be able to support the ROI and associated costs of a traditional DAS solution that requires extensive

planning, RF design, engineering, and costly maintenance, as well as extensive budget and contract negotiations with multiple

vendors, integrators, and the operators themselves.

But the cost of a traditional DAS solution typically puts them out of range of most middleprise venues. Simpler solutions

such as femtocells and Wi-Fi calling are available but do not have the reliability, quality of service, or management

capabilities that a business requires. Venues that range in size from 10,000 to 200,000 sq. ft. are particularly challenged

with the price/performance gap, because they are too large for affordable consumer-grade solutions and too small for

high-performance DAS.

Cel-Fi QUATRA addresses this gap by often eliminating the need for over-costly RF engineering tools, using Cat 5e (or

better) cabling to connect the NU with the CUs, and powering the entire system via Ethernet (PoE) from a single power

supply at the NU. This also means the CUs can be easily mounted just about anywhere, from wall to ceiling, wherever

coverage is needed.

Nextivity chose to standardize on dedicated Cat 5e cabling to simplify IT requirements. (Higher grade cable can be used, but is

not required.) The NU and CU may be separated by as much as 200 meters when the optional QUATRA Range Extender (QRE)

is placed inline. The QRE is also powered by the NU, and doesn’t require additional power.

Cel-Fi QUATRA includes support for MIMO, and provides up to 75 MHz of combined channel bandwidth across four independent

cellular bands. This provides flexibility for supporting mixed 3G and 4G networks on location.

All of this translates into an exceptional Total Cost of Ownership (TCO) for the middleprise, and faster deployment times.

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Cel-Fi QUATRA In-Building Enterprise Cellular System Configurations Cel-Fi QUATRA is flexible and scalable to support a company’s future growth. The optimum donor signal configuration is

determined by applying some basic use-case principles.

Off-Air Configurations Off-Air configurations use capacity from the operator’s existing macro network, extending it indoors where it is needed. This

can be the fastest and easiest way to provide indoor coverage, not requiring any fixed backhaul (small cell or femto), contracts,

or lengthy permit processes.

This system can take advantage of the NU’s internal antennas, or it can be connected to an external antenna. (Nextivity offers a

Wideband MIMO Antenna that is the perfect donor source for this.) Using a high-gain external directional donor antenna can be a

good way to improve signal quality. The certified installer attaches the antenna and runs through the setup procedure. Nextivity also

offers mounting solutions, an outdoor pole mount, and an indoor/outdoor wall mount. Guided by Nextivity’s Antenna Positioning

software, in minutes the antenna can be mounted, positioned, and aimed properly for best donor signal input. Quality of the donor

signal provided to the system is perhaps the most important factor in the installation outcome for an off-air configuration.

Another advantage of the off-air configuration is that CUs only need to be placed where coverage problems exist in the

building. In this configuration, the existing macro signal is only being boosted where it is lacking, and a handset that migrates

between Cel-Fi QUATRA and macro-covered areas is simply seeing a better macro signal everywhere.

Quatra Off-Air or Supercell Configuration

Coverage Unit

Coverage Unit

Coverage Unit

Coverage Unit

SmallCellNetwork

Unit

COVERAGEUNIT

COVERAGEUNIT

NetworkUnit

COVERAGEUNIT

COVERAGEUNIT

MIMO Panel Antenna

(PoE–Cat5e)

(PoE–Cat5e)

(PoE–Cat5e)

(PoE–Cat5e)

(Up to 200m)

INPUT

SupercellCONFIGURATION

Off AirCONFIGURATION

Supercell™ Configuration In the Supercell configuration, a small cell is used as the donor for Cel-Fi QUATRA. (Any small cell can be used with QUATRA,

as long as the supported bands of the small cell match the bands supported by QUATRA. There are several QUATRA band

variations available.) The Supercell created by the small cell/active DAS hybrid provides uniform access to the capacity

introduced by the small cell. Supercells are inherently uncomplicated from a planning and deployment point of view, and are

far more resilient to the potential of interference. Larger or more densely populated installation sites can often benefit from

the signal capacity delivered by a dedicated small cell donor.

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This configuration facilitates a uniform signal distribution throughout a larger area. Additional Cel-Fi QUATRA systems may be

used to expand coverage up to 200,000 sq. ft. per (typical) small cell.

Optionally, while waiting for a small cell to be delivered, the integrator can install Cel-Fi QUATRA off-air for immediate extension

of cellular coverage. When the small cell is installed, the external donor antennas are disconnected and the small cell is

connected to the NU.

Supercell Advantages

The Supercell configuration — i.e., Cel-Fi QUATRA connected to a small cell — has three key advantages over a small cell

installed alone. These are:

1. Small cell dominance

2. Elimination of problems related to multiple small cell interference

3. Reduced small cell overhead and OPEX resource requirements (fewer small cells are required for the space).

Advantage 1: Supercell Dominance

Larger or more densely populated installation sites can often benefit from the network capacity delivered by a dedicated small

cell. This means three things to the operator (and the enterprise):

1. The installation should provide enough signal dominance (power) over the outside macro network so in-building calls

stay in-building on the small cell where they belong.

2. The local small cell off-loads traffic from the macro network, freeing up capacity for other macro network subscribers.

3. If the site suffers from network interference problems, such as pilot pollution in a high-rise building where too many

cell sites are visible and interfering with each other, small cell dominance must be able to overcome the interference

signal energy that is present.

In the typical example below, the building suffers from a lack of signal at its interior, while the perimeter areas of the building

are being adequately served by competing macro cells.

Small Cell competes with the Macro network.

Lack of signal in building interior

Small Cell needs to dominate over the Macro network signal at building perimeter.

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If a small cell is installed in the center of the building, its signal power falls off as callers get closer to the perimeter. This results

in service being handed-off to the outdoor network, which defeats the purpose of adding small cell capacity.

WEAKER Small Cell signal at perimeter.

LEGEND

-60 dBm

-80 dBm

-100 dBm

-120 dBm

Centrally LocatedSmall Cell

Service Blind Spots

SC

WEAKERSmall Cell Signals at Perimeter

Now consider the Supercell case which distributes local capacity in a more uniform fashion. The result is that more areas are

covered, and power density (small cell dominance) is improved at the building perimeter.

Cel-Fi QUATRA tethered

to a small cell

LEGEND

-60 dBm

-80 dBm

-100 dBm

-120 dBm

CU 1

CU 4

CU 3

CU 2

STRONGERSmall Cell Signals at Perimeter

STRONGER Small Cell signal at perimeter.

In this case, the result is a 14dB improvement for the perimeter offices, plus better coverage overall throughout the venue.

This helps to ensure that local cell phones will be properly served by the local system, and that the macro network will be

properly off-loaded as the operator intends. .

Advantage 2: Potential Interference from Multiple Small Cells

Similar to macro network cells, small cells may interfere with each other where they overlap, causing reduced performance.

The Supercell configuration resolves this problem by creating a large single composite cell and eliminating handoff regions

between multiple small cells.

The Supercell Advantage

Small Cell Interference Zones

Supercell Seamless Service

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Advantage 3: Small Cell Overhead and Opex

Each small cell must have its own high bandwidth backhaul that connects it to the operator’s gateway/core network. Therefore,

additional small cells result in an increase in cumulative backhaul requirements and OPEX that must be considered. Some

enterprises will have plenty of overhead bandwidth and can draw from that with small cells, but some will need to increase

bandwidth, which comes at a cost. Each small cell comes with guidance on the bandwidth consumption, so the enterprise can

easily determine if current bandwidth is sufficient.

Small Cells require backhaul.

Internet

Quatra and IoT LTE-based cellular IoT solutions are new on the market, with the first commercial deployments taking place over

the last six months. Cat M1 LTE is gaining a lot of momentum in IoT. These technologies are subject to similar in-

building penetration challenges and resulting coverage problems as cellular. For example, many reviews of Apple’s

new LTE-based iWatch product cited LTE coverage as an important metric in the usability of the product, impacting its

performance and customer-satisfaction.

In an LTE-based IoT infrastructure, Cel-Fi QUATRA offers several advantages:

1. It is transparent to the network. There is no additional latency or setup required. A device could be installed in

a concrete bunker, yet the device would appear on the network as if it was sitting in a wide-open coverage area

without any structural obstacles. For mission-critical business solutions that rely on real-time communications,

this is an important option.

2. Unlike mesh networks, connected devices that are inside the coverage bubble of a Cel-Fi QUATRA system are not

required to do any additional networking, so they can be much lighter weight in terms of capability, and power

consumption. They can operate as intended, waking only when prompted, or on a timer. This delivers the 10-year

battery life desired by the IoT industry.

3. Buildings with IoT solutions being serviced by Cel-Fi QUATRA have a lot of flexibility, since nodes can be added or

subtracted without any special setup or configuration. Connected devices can be fully mobile and not reliant on

tethering from a cable or network connection.

Unlike other options (e.g., simply adding an antenna to the IoT router), using Cel-Fi QUATRA will not only connect the IoT node

connected in a high-speed low latency connection, all LTE services, like voice calling, will be improved.

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Cel-Fi QUATRA IoT Solution

MIMO Antenna

NU

CU

CU

IOTNODE

IOTNODE

IOTNODE

IOTNODE

IOTNODE

IOTNODE

IOTNODE

IOTNODE

IOTNODE

IOTNODE

Conclusion The industry has struggled to provide affordable indoor cellular coverage solutions for middleprise venues under 200,000 sq.

ft. — until now. Existing consumer-grade solutions have been limited in performance, while active DAS has been too complex

and costly. The Cel-Fi QUATRA In-Building Enterprise Cellular Solution is the first to meaningfully address the obstacles to

indoor densification for the middleprise, so that massive and rapid deployment can occur to resolve black holes, dropped calls,

and poor cellular quality that plague most companies in this space.

Cel-Fi QUATRA builds on the digital architecture of Nextivity’s proven operator-class indoor coverage solutions to improve

indoor cellular service in the middleprise with the best TCO of any solution available on the market.

Configurations are flexible and can be scaled to the unique needs of each venue, future-proofing the system for company

growth. Off-air configurations are designed to quickly bring outdoor coverage indoors. Supercell configurations are designed

to improve the effectiveness of local small cell capacity, while providing better coverage for larger or more densely populated

facilities and effectively offloading the macro network.

With Cel-Fi QUATRA intelligence and toolsets, installations are highly optimized. CAT 5e cabling, Power over Ethernet, and RF

over Ethernet all help to make the certified installer’s job easier, and keep the CAPEX and OPEX of the system at an affordable

level for most middleprise budgets.

Cel Fi QUATRA is available through distributors around the globe. For more information, visit www.cel-fi.com/QUATRA. To

become a certified partner, visit www.cel-fi.com/partnership.

About the AuthorJoe Schmelzer is Senior Director of Products at Nextivity. He has developed a variety of products

and industrial devices for chipset vendors, OEMs, and service providers, including products for Sony,

Qualcomm, Google, Verizon Wireless, AT&T, Dell and HP. He enjoys speaking opportunities and writing.

U.S. Headquarters: Nextivity Inc.16550 West Bernardo Drive, Bldg 5, Suite 550, San Diego, CA 92127, USA+1 858.485.9442 tel • +1 858.485.9445 fax

cel-fi.com

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