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What is In-Building Cellular Coverage?

Many buildings - from brand new modern megaliths to protected heritage housing - were not built with accessing wireless radio waves in mind. It is common to find dead spots within a structure and not just in stairwells, carparks and lifts.

An In-Building Coverage solution will capture the radio wave signal from the nearest cellular tower, amplify the signal strength, and distribute it within the building. The solution components usually include a rooftop antenna, smart signal repeater(s), signal splitters,  and a series of cabled internal antennas to distribute the signal throughout the space. 


Solving In-Building Cellular Coverage

In-Building cellular coverage issues are surprisingly common.  It is difficult for radio waves to penetrate modern building materials, to permeate every space within a building, and to reach into underground carparks or stairwells.

With 80% of all mobile calls being made or received indoors, poor reception is frustrating and has a significant impact on productivity and employee satisfaction. 

An IBC solution will boost signal strength and distribute signal reach within an enclosed space.

The key components of an IBC solution by MobileCorp are:

  • Outdoor Wideband Directional Antenna 
  • Intelligent smart signal booster - also known as a repeater - like the CEL-FI GO G41 or G51
  • Signal splitter device (if required)
  • Either Omni Dome Antenna(s) for ceiling mounting or Wideband Panel Antenna(s) for wall mounting
  • Additional server antennas for venues with more floors or dense interior walls, while a higher gain LPDA-R antenna is available for sites with weaker outdoor signals.
  • Cables and connectors
  • Professional Installation by a certified radio engineer
  • Testing



In-Building Coverage solution architecture

There are three parts to a simple IBC solution - the external or donor antenna (1), the network unit (2), and the server antenna (3).

The donor antenna is positioned to access maximum signal from a cellular tower and is usually installed on a roofline or near a window.

The signal is transmitted via cabling to the network unit - also referred to as a smart signal repeater. CEL-FI GO repeaters can deliver max signal gain of up to 100 dBi, equivalent to a 1000x uplift.

The repeater will amplify the signal and push it via cabling to the server antennas which are placed in the areas of the building with the weakest signal.





   IBC installations 1,2, 4 antenna


In-Building Coverage Commercials

When it comes to calculating the cost of your IBC solution, there are three key factors to consider: hardware, installation, and management.


In terms of hardware, the costs will not vary widely from one reseller to the next as there is only one manufacturer whose repeaters have been approved for use in Australia by the three national carriers - Telstra, Optus, and TPG Telecom - and the Australian Communications and Media Authority. This equipment is CEL-FI by Nextivity. The cost of hardware for a simple IBC solution with an external antenna, CEL-FI repeater, omni internal antenna, and cables will be around $1,700. For a large warehouse that may require multiple rooftop antennas, splitters, cabling, and 12-15 internal antennas, the cost will be approximately $20,000.


Installation costs are the most variable aspect of calculating an IBC solution's cost. The cost of installation is mainly  labor expenses plus any specialist equipment, such as a scissor lift, that may be required to access the rooftop. Each site is unique, and the cost of installation may vary significantly depending on the size and complexity of the deployment. Some sites may require onsite inductions, SWMS lodgement, Working from Heights certification, police checks, WorkCover, and Indemnity Insurance. Generally, installation costs will range from $5,000 upwards.


With the shift to the cloud, the management of In-Building Coverage solutions has become possible. Managed services can include access to a technical service desk, proactive connectivity monitoring, OTA firmware updates, remote and on-site troubleshooting. The cost of an IBC managed service will vary depending on the number of devices under management and the managed service inclusions but range upwards from $40+ per device per month.


MobileCorp's 4-Step IBC Deployment


Step 1. Site Assessment 

MobileCorp will attend onsite to determine the viability of an in-building solution.

This includes identifying barriers to success, testing signal throughput, and determining the optimal cell tower and antenna placement.

5G line of sight png


Step 2. Solution Architecture

MobileCorp will design and map out your solution architecture.

A written Proposal with detailed network diagram, bill of materials, installation timeline, and itemised quotation will be prepared.


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Step 3. Installation

MobileCorp certified radio engineers will deploy your solution onsite including rooftop antenna installation, cabling, repeater positioning, internal antenna cabling and installation, and testing.


CEL FI Certified Installer logo


Step 4. Managed Service

MobileCorp will set up your Wave application and register your CEL-FI devices with ACMA. Our optional managed service will proactively monitor your connectivity, push firmware updates, navigate cell tower changes, provide technical service desk to manage remote and onsite troubleshooting.


cel-fi certified logo


MobileCorp - your leading Australian IBC specialist

MobileCorp is a leading In-Building Coverage solution specialist and MSP.

Based out of Mascot, Sydney, we design, install, remediate, and manage IBC solutions nationwide. We are certified CEL-FI Enterprise Installers and a Telstra Enterprise Partner.

All of our solutions are built around Nextivity's world-leading CEL-Fi products which are licensed by the ACMA for use with all Australian carrier networks - Telstra, Optus and TPG Telecom (Vodafone).

Combined with our industry knowledge, project management expertise, and deployment experience, MobileCorp delivers IBC projects on time and on budget.

Some of our projects include:

  • CEL FI Certified Installer logo

    Wotso WorkSpace at North Head, Sydney Harbour National Park
  • Xylem warehouse, Kemps Creek
  • Chep warehouse, Kemps Creek
  • Coates Hire Office, Darwin
  • Whitehaven Coal
  • Thales, Managlore
  • Sydney Water
  • BGIS
  • Clean Energy Regulator


IBC brochure cover 3D


CEL-FI by Nextivity

MobileCorp utilises world-leading IBC hardware by Nextivity including the CEL-FI GO suite of stationary and mobile Smart Signal Boosters.


Why CEL-FI ?


CEL-FI products by Nextivity are the only mobile signal repeaters that are legally approved for use in Australia. They are approved for use with all Australian carriers and globally with more than 200 network operators in over 100 countries. CEL-Fi repeaters are unconditionally network safe. It is illegal to use any repeater that is not approved by the ACMA.



How do CEL-FI solutions work?


Nextivity’s CEL-FI products are built upon the revolutionary IntelliBoost® processor and WAVE software. The IntelliBoost® proprietary chips used in Nextivity CEL-FI cellular coverage solutions provide smart, real-time processing and include multiple patented designs and processes.

The performance of CEL-FI products is unmatched in the industry, CEL-FI devices deliver industry-leading signal gain with 3x the coverage footprint for voice and data.

CELFI IntelliBoost Chip technology


CEL-FI Hardware


5G In-Building Coverage just got real!

The CEL-FI GO 51 is the world's first 5G-native intelligent signal booster for in-building coverage.

Compatible with all Australian carrier 5G networks - the  G51 targets coverage challenges in the mid-band 5G NR frequencies.

The solution can deliver Max Signal Gain of up to 100 dB - 1000x stronger - at stationary sites; and up to 70 dB or 700x stronger for vehicles.

Cel Fi Go 51 with box


The CEL-FI GO G41 Smart Signal Repeater is a powerful carrier-grade solution for overcoming cellular coverage issues in indoor environments.

Providing up to 100 dB gain, GO G41 offers class-leading 4GLTE voice and data performance.

In addition to providing cellular coverage up to 3,000m2 when configured with the included donor and server antennas, the system can be expanded with outdoor or additional server antennas for an increased coverage footprint. 



The CEL-FI ROAM R41 mobile cellular coverage solution delivers reliable 3G, 4G, and 5G connectivity inside vehicles and boats. 

Launched in Australia in mid-2023, it runs on the 4th generation Nextivity Intelliboost chip which delivers channelised coverage for specific mobile network operator signals. 

The ROAM R41 offers enterprise-grade performance to solve poor coverage and enable dependable calling, texting, and streaming on the move. The system features plug-and-play operation for quick and easy set up, improving connectivity in any car, truck, RV, or boat within minutes. ROAM R41 also supports carrier switching through the Nextivity WAVE App for iOS and Android devices.

Web Roam R41

CEL-FI Wideband Directional Antenna

The CEL-FI Wideband Directional Antenna is an outdoor vertically polarised directional antenna; with 10dB gain in the low bands and 11dB gain in the high bands. The weather resistant housing is built with UV stabilised ABS plastic. Optimized for Cel‑Fi products, the CEL-FI Wideband Directional Antenna can be used with the CEL-FI WAVE Antenna positioning app. The unit includes standard brackets for mounting, and can also be used with the Cel‑Fi Pole Mount. A 10K ohm resistor is part of the antenna.

  • Boosts Cell Signal by up to 11 dBi
  • 700 – 2700 MHz Frequency
  • Vertical Polarisation
  • Uni-Directional
Web Cel Fi Directional Antenna

CEL-FI Outdoor LPDA-R Antenna

The CEL-FI LPDA-R Antenna offers a powerful 12 to 14 dBi gain (depending on carrier frequency) over 617–4000 MHz and is designed to reduce out of band noise, to improve SiNR and overall signal quality. Mounting is made simple with included U-Bolts. This CEL-FI product also features a 10K ohm resistor that enables the antenna connection to be validated by CEL-FI Network Units equipped with the capability.

  • 12–14 dBi gain
  • Narrow beam-width to reduce noise
  • Rugged construction for harsh environments
Web CEL FI Outdoor LPDA-R antenna

CEL-FI Indoor Omni Dome Ceiling-Mounted Antenna

The CEL-FI Indoor Omni Dome Antenna receives and transmits signal in a 360° pattern and are compatible with the 698 – 2700 MHz frequency ranges that include 3G and 4G signals. They come with either an N-type Female Connector.

  • 3G/4G/LTE wideband cellular antenna
  • N-type Female
  • Omni-directional
Web CEL_Fi_Indoor_Omni_dome_ antenna brochure

CEL FI Wideband Panel Antenna

The CEL-FI Wideband Panel Antenna is an indoor/outdoor cellular wideband directional antenna with 6 dB gain in the low bands and 10 dB gain in the high bands. The weather resistant housing is built with UV stabilized ABS plastic. Optimised for CEL-FI products, the CEL-FI Wideband Panel Antenna can be used with the CEL-FI WAVE Antenna positioning app. The unit includes standard L-bracket only.

Image shows MobileCorp deployment at Xylem warehouse, Kemps Creek.

  • Boosts Cell Signal by up to 9 dBi
  • 700 – 2700 MHz Frequency
  • Vertical Polarisation
  • Directional
Web CEl-Fi_wideband_Antenna-Panel
Cel Fi Go range

The Problem with In-Building Coverage


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cityscape ibc_ signal barrier web
Cellular technology requires access to radio waves, however the higher the wave or frequency, the smaller the propagation distance.
5G with its range of frequencies extending from mid-band to mmWave high band is particularly susceptible to interference.
Even 4G may deliver a good signal outside but not extend to inside a building. Black spots can occur inside buildings in the CBD, city suburbs, urban fringe, as well as in remote and rural locations.
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Man-made barriers

Modern building materials such as steel, brick, concrete, and glass all interfere with the radio waves emitted by cell towers.

These materials refract and reflect the waves preventing the radio signal from penetrating indoors.

Low-emissivity (low-E) glass and LEED Green Building initiatives, also interfere with radio frequency (RF) signals. 

Being underground or in a building surrounded by other high rise buildings may also prove difficult to access a reliable signal, or even any signal. 

ibc glass and concrete barriers web

Fresnel zone barriers

In point to point wireless transmission, it is important for the line of sight between the two points to be free of interference. Any obstruction in the LOS can result in a loss of signal.

The 3D elliptical region between the transmit antenna and the receive antenna is called the Fresnel Zone. The size of the ellipse is determined by the frequency of operation and the distance between the two sites.

Any object that impinges on the fresnel zone can disrupt radio frequency signals. This can include natural barriers like hills and trees, or man-made barriers like buildings. Even the weather - rain or wind - can disrupt the signal.

fresnel zone web

Cell tower barriers

The further the distance from the cell tower to the receiving antenna,  the weaker the signal will be.

4GLTE will reliably broadcast over an area of 2-5km in an urban area and may reach well over 10km in a less congested rural setting. 5G,operating on a higher frequency with small cell technology, must be much closer to the target, ideally within a kilometre. 

Congestion on the tower is also a potential barrier. Each cell tower has a finite amount of bandwidth, processing power, and backhaul capacity. These resources are shared among the devices connected to the tower. When the number of connected devices or the amount of data being transmitted surpasses the available resources, congestion can occur. Congestion will cause slower data speeds, increased latency, and potentially dropped connections.

telstra rigger up tower

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Speak to our MobileCorp Representative

To get started with a technology solution, call us on 1800 243 252

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