How Do Cell Phone Signal Boosters Work & Which One to Buy?

Determining which affordable cell phone signal booster is the right one for your specific application can be very confusing. With so many different products on the market, and many of them having specifications that seem very similar, the process can become very tricky.

To help you find the right cell signal booster, we have written this article in two parts. In the first part, we explain how your phone and signal boosters work together. We strongly recommend that you read this part, even if you're not that technical. Having a basic understanding will help you select the right kit and get more bars.

In the second part of article, we will make specific product recommendations for various scenarios. Selecting the right cell phone signal booster depends on a number of factors, and we make our recommendations based on specific criteria that you're likely to have. If you feel that you don’t want to spend time learning more about the theory, feel free to use the hyperlinks provided below to skip straight to the product recommendations, or directly buy cell phone signal booster using our automated tool that finds you the most suitable kit at the most affordable cost.

Index:

1. How phones and cell phone signal boosters work together?
2. Product Recommendations.

A. How phones and cell phone signal boosters work together?

Being of the latest technological devices, a cell phone signal booster may often seem very complicated. In this article, we will explain in simple how a cell phone signal booster works, and will also guide you on which accessories to choose.

Improper installation is a major reason why signal strength does not improve after installing a boosting system in many cases. Cell phone signal boosters will not work properly if they are installed incorrectly. That is why we will also explain how your signal booster should be installed to make sure you get the best performance.

In the first sections, the basics are covered. As we go along, we will go into the full detail that you need to not only select a suitable booster, but also how to install it properly.

Contents:

1. Cell phone technology generations (2G, 3G, etc.).
2. VoLTE (Voice over LTE).
3. Bars mean more than signal strength.
4. Why are Signals Noisy and/or Weak?
5. Frequency Bands.
6. Signal Booster Operation.
7. Measurement of Signals.
8. Amplifier Specifications.
9. FCC Regulations for Cell Phone Signal Boosters.
10. Choosing Outdoor Donor Antennas for an In-building Booster.
11. Number of Indoor Antennas needed for In-building Boosters.
12. Choosing Indoor Antennas for an In-building Booster.
13. Summary of Guide.
14. Terminology.

1. Cell phone technology generations (3G, 4G, 5G, etc).

With new cell phone technologies continuously being released in the past 3 decades, it has become convention to refer to each new wave as a generation. 3G is therefore the third generation, 4G the fourth generation, etc. When LTE was first released, it was only used for data, but that has been changing as more and more carriers now also use 4G LTE for voice calls and data.

The different technologies are briefly described below:

• 2G: In the beginning of the 1990s, the 2nd generation cell technology was released as two different types - GSM and CDMA. As data was not commonly used in those days, 2G has a very limited support for data transmissions. Different carriers decided to use different 2G technology types, with Sprint and Verizon choosing CDMA, while T-Mobile and AT&T went the GSM route.
• 3G: Carriers started to roll out 3rd generation cellular technology in 1998. As with 2G, there two 3G types: UMTS/ WCDMA/ HSPA and CDMA2000/ EVDO. Interestingly, Sprint and Verizon again opted for the same type (CDMA2000/ EVDO), while T-Mobile and AT&T went with UMTS/ WCDMA/ HSPA.
• 4G: After the release of 4th generation cellular networks, carriers broke the previous pattern and all used LTE technology. LTE acronym stands for "Long Term Evolution". It intended the platform to stay the same while wireless data transfer speeds continue to increase. With LTE, increased connection speeds are made possible. Initially, 4G was only used for data transmissions, while 2 and 3G were still used for voice calls. This has however changed in the past number of years and 4G LTE is fast becoming the major technology for both voice and data services.
• 5G: The specification for the 5^th generation technology has not yet been finalized. Although exact details are therefore not yet clear, it is highly probable that 5G will have millimeter wave signals resulting in high frequencies. This will allow data rates to be increased significantly.

2. VoLTE (Voice over LTE).

Voice over LTE has been rolled out by carriers for the past three years. VoLTE will allow phones to do voice calls over 4G LTE networks, without having to connect to 2G or 3G networks. The major carriers have rolled out this technology to various degrees:

• T-Mobile is the leader in rolling out VoLTE across US and was the first to do so. Any device manufactured in past 3 years, for example the iPhone 6, 7, 8, will use LTE to make voice call if the signal is present. Your phone can be manually set to continue to use 2G/3G within your phone settings section, if that coverage is stronger than 4G LTE.
• Verizon has implemented VoLTE across USA. As with T-Mobile, devices manufactured in the past 3 years will automatically make voice calls over LTE providing that it is present. Verizon has announced that it will be shutting down its 2G network, probably within the next two years. Your phone can be manually set to continue to use 2G/3G within your phone settings section, if that coverage is stronger than 4G LTE.
• AT&T also has VoLTE available across the country, meaning that newer devices will also use the technology in areas where signal is available. AT&T has already closed down their 2G network, and is only using 3G and 4G LTE networks. Your phone can be manually set to continue to use 3G within your phone settings section, if that coverage is stronger than 4G LTE.
• Sprint has fallen behind other carriers and has not yet rolled out VoLTE. It relies solely on the 3G network for making voice calls.

3. Bars mean more than signal strength.

A common perception is that bars on a cell phone are only an indication of signal strength. Although this is partly true, signal bars actually show two different parameters - signal strength and signal quality.

• Signal strength: This is measured in dBm and is an indication of how strong the cell signal is when it gets to a phone.
• Signal quality: This is measured in dB and indicates the ratio between the signal and the interference and noise received by a phone.

It is important to understand that signal quality limits how many bars are shown on a phone the same way signal strength does. If you know this, it will help tremendously when you install a cell phone signal booster.

As mentioned before, many cell networks nowadays use LTE for voice and data services. In these networks, signal quality and signal strength are typically referred to as RSRP and SINR.

• Signal to Interference & Noise Ratio (SINR): This is an indication of the quality of a LTE signal. If the SINR is more than 10 dB, the signal is clear signal, while a value of less than 5 dB indicates that the quality of the signal is low.
• Reference Signal Received Power (RSRP): This measures the strength of an LTE signal. A reading of about -70 dBm indicates a strong signal, -100 dBm represents a weak signal.

We will describe how the SINR and RSRP values can be measured in the section on "Measuring Signals".

4. Why are Signals Noisy and/or Weak?

Four factors cause signals to become weak and/or noisy, and these will reduce the bars shown and result in slower data rates and more dropped calls. A number of the factors are often present at the same time at specific locations.

• Distance from cell phone towers.

  Cellular signals get weaker as they travel through air. If the closest cell tower is far away, it is likely that the signal will be weak. The radio receiver inside the cell phone will find it difficult to hear the signal from the cell tower ("downlink"), while the cell tower will find it difficult to "hear" the signal from the cell phone ("uplink").

• Interference between cells.

  Cellular technologies, including 4G LTE, utilize one frequency to transmit signals from all cell phone towers. When a phone is situated between multiple towers that have about the same signal strength, signal towers not being used will interfere with the tower you're using to connect. This reduces the signal quality, known as RSRP and SINR in LTE. Interference between cells is a main cause for weak signals in urban areas.

• Geography.

  Any obstacle between a cell tower and a cell phone blocks the signal. Therefore, the natural geography of an area can play big role. Mountains, hills and valleys can all block the signal and cause weak signals.

• Building materials and vehicle bodies.

  If signal outside buildings and/or vehicles is strong, it does not mean that the signal will also be strong inside the structure. Any material, including metal, wood, drywall, concrete, and glass all attenuate signals, causing it to be weaker inside.

Cell phone signal boosters will help resolve all of the causes of weak signals mentioned above. For each case however, there're subtle differences that need to be catered for to ensure that equipment is suitable for the specific application.

5. Frequency Bands.

The FCC licenses specific frequency bands to different carriers to provide cellular service. In America, four frequency bands are used and most of the signal boosters we supply support them.

• 700 MHz: This band contains LTE bands 12, 13, & 17 and is used exclusively by T-Mobile, Verizon and AT&T for 4G LTE services.
• 850 MHz: Although this cellular band contains LTE band 5, it is mostly used for 2G and 3G services by only Verizon and AT&T. Both these carriers are however starting to use this band for LTE.
• 1900 MHz: This band is also known as the PCS Band and contains LTE band 2. The 4 major carriers all use this band for a mixture of 2G, 3G, and 4G LTE services.
• 2100 MHz: AWS Band contains LTE band 4 and is used by Verizon, AT&T and T-Mobile for only 4G LTE.

Although there are 3 additional frequency bands often utilized for specific cases, most broadband cell signal boosters do not cater for these.

• 850MHz: This extension band (LTE band 26) is only used by Sprint.
• 2300 MHz: AT&T uses the LTE Band 30, but only in selected areas.
• 2500 MHz: Sprint uses the LTE Band 41 only for LTE services.

All carriers use different frequency bands in any specific area. Smartphones switch between bands automatically. This is determined by which band has the best strength and clarity at a specific location.

It is important to know that with higher frequencies, it is easier for the signal to be weakened. A 2300 MHz signal will for example find it much more difficult to penetrate buildings than an 850 MHz signal would. Higher frequencies do however have the capability of transferring more data @ higher speeds.

Booster installations are affected in the same way. Even with a signal booster installed, the high frequencies would still be decreased easier. Boosting signals on the 850 MHz band within buildings is therefore much simpler than boosting signals on higher frequency bands.

6. Signal Booster Operation.

Signal boosters amplify cellular phone signals being sent from, and received by smart phones from cell towers that are close by. Signal boosters typically consist of three components:

• Amplifier: Amplifiers are sometimes referred to as "Bi-Directional Amplifiers" (BDA) or boosters. This device amplifies the signal sent by a tower to a cell phone and also the signal sent from phones to towers. The amplifier is connected to two antennas via coaxial cables.
• Donor antennas: Donor antennas are installed on roofs of buildings, and receive and send signals from and to the cell tower. With some buildings, directional donor antennas are used. This allows for aiming at a specific tower, which results in stronger signals and reduces interference between cells.
• Indoor antennas: Indoor antennas send and receive signals from cellphones. The two indoor antennas most commonly used are dome antennas and panel antennas.

7. Measurement of Signals.

Both signal quality and signal strength have an impact on how many bars are displayed on a phone. The sections below describe how each of these can be measured more accurately than just relying on the signal bars icon on your cellphone.

LTE Signal Quality (SINR):

• Signal quality is unfortunately difficult to measure on some cellular phones.
• On iPhones, Field Test Mode needs to be accessed to find information.
• For some Android phones, you will need to download the LTE Discovery app to display signal quality. Pressing on the signal bar icon in the "Signals" tab for long will show a menu where the option to show SINR can be enabled.

LTE Signal Strength (RSRP):

• Signal strength is normally easier to find than signal quality.
• On iPhones, the "Field Test Mode" needs to be selected to see signal strength.
• Although some Android phones show the signal strength under settings, you can also download the LTE Discovery app. The signal strength will be shown at the top left of the "Signals" tab.

8. Amplifier Specifications.

There're two important amplifier specifications that should be looked at when deciding which equipment to buy. These're downlink output power and gain. A short description of each is given below.

• Downlink output power is measured in dBm. This represents is the maximum signal an amplifier can retransmit inside vehicles or buildings. The downlink output power determines an area the system can cover when there's enough signal to the amplifier.
• Gain is measured in dB and represents by how much the signal is amplified. Bigger gain values show that the signal from donor antennas are amplified more.

Although both the specifications are important, they apply to different scenarios:

• If outdoor signal is strong, i.e. more than -70 dBm, amplifier may be constrained in downlink output power. The most important specification for a situation where the donor antenna has a strong signal is the downlink output power. This situation will likely result in the maximum output power of the amplifier being utilized, making the downlink output power spec. of the cell phone signal booster an important factor.
• If outdoor signal is weak, i.e. less than -80 dBm RSRP, amplifier will be very constrained in gain. The most important specification for a situation where the donor antenna has a weak signal is the gain of an amplifier. This situation will likely result in the maximum gain of the amplifier being utilized without reaching the downlink output power spec. of the cell phone signal booster. In this situation, it makes sense to get an amplifier with the highest gain. All-carrier maximum gain consumer indoor boosters available per FCC regulations = Up to 70 dB. All-carrier maximum gain consumer outdoor vehicle boosters available per FCC regulations = Up to 50 dB.

9. FCC Regulations for Cell Phone Signal Boosters.

The FCC (Federal Communications Commission) regulates usage of cell frequencies in USA. The FCC released new regulations in 2014 that apply to cell phone signal boosters sold in United States of America. Two sets of regulations were created. The first set was for boosters that are carrier-specific and only amplify signals of one carrier. The second set was for broadband equipment that amplify all cell signals from all carriers.

Regulations for Carrier-specific cell phone signal boosters.

• Amplifier gain must be less than 100dB for any band.
• The downlink output power of the system must be less than 12 dBm per 5 Mhz block. This includes cable losses.

Regulations for Broadband cell phone signal boosters.

• Amplifier gain must be less than 64dB for the 700MHz band and less than 65dB for the 850MHz band.
• The downlink output power of the system must be less than 12 dBm. This includes cable losses.

Since the FCC limits the gain of broadband boosters, it makes sense to, where possible, use carrier-specific boosters for situations where the signal at the outdoor donor antenna is extremely weak.

10. Choosing Outdoor Donor Antennas for an In-building Booster.

The performance of cell phone signal boosters can be improved dramatically by selecting the correct outdoor antenna and aiming it the right way. Selecting the correct donor antenna can help in 2 ways.

• A directional donor antenna will allow focusing in a specific direction, thereby improving the signal clarity. Both coverage and the number of bars shown will be improved.
• Donor antennas often have an internal gain, measured in dBi. This internal gain will add to the overall gain of the cell phone signal booster that is being installed. If outdoor signal is weak, an outdoor antenna with a high gain should increase the system's downlink output power, resulting in an increased area being covered indoors.

Omni Antennas (Omni-directional).

Omni-directional antennas are most suited to situations where there is clear, strong outdoor signal. Omni antennas are easier to install when compared to a directional antenna, as no aiming is required. You should however ensure there're at least 3 bars of signal in area where the antenna is being installed.

Directional Antenna (Uni-directional).

Although a directional antenna takes more work to install and aim, these are recommended for areas where there's either a weaker outdoor signal, or when the signal is strong, but noisy (low RSRP or SINR).

Aiming directional antennas, although tricky, has a number of benefits.

• Noisy outdoor signals are often caused by inter-cell interference. This happens when there're a number of towers nearby that all broadcast on one frequency. A directional antenna enables focusing on only one relevant cell tower, thus improving indoor coverage.
• As mentioned before, an antenna's gain is added to the gain of the signal booster. With a weak signal, a highly directional antenna will gain as much 12 dB signal strength.
• The performance of broadband boosters are often affected by what is called a "near-far effect". This happens when the signal from a tower that is close by saturates an amplifier. This in turn prevents signals from a weaker carrier from being amplified. Directional antennas enables the focusing on a distant tower to balance the incoming signals better.

It is a common misconception that using directional antennas will result in one carrier's signal being improved, while signals from other carriers are sacrificed. This rarely happens as cell towers of different cell service providers are normally clustered in a single area, often using the same pole. This means that a specific direction is most often the best for all carriers. Directional antenna also don't only pick up signals from one direction, although the signals from other directions are slightly reduced. A directional antenna will often provide excellent coverage from two towers in opposite directions. This is because one of the signals is often stronger, and the directional antenna thus allows for aiming and equalizing the signal coming from each tower.

How Directional Antennas are aimed.

Two people are needed to aim a directional antenna - one needs to take signal measurements inside the building while the other needs to aim the antenna. The person on the roof should experiment with both location and direction to find the optimum position. Although this can be time-consuming, it could have a huge effect on the performance of the signal booster.

There're specific devices available that simplify aiming directional antennas. These will show both SINR (signal clarity) and RSRP (signal strength), making it easy to test various antenna directions and locations to find the best signal.

11. Number of Indoor Antennas needed for In-building Boosters.

In-building cell phone signal boosters often have ports that cater for additional antennas. Although there is not really a simple way to determine how many antennas are required, a general rule of thumb is that the more antennas are used, the better. Signals travel through coaxial cable easier than they do through air, doors or walls. If the signal is distributed through a building by using coaxial cable, the coverage will be much more consistent.

It does however not make sense to install hundreds of antennas, simply because of the cost that would incur and signal loss that would incur with all that cabling involved. For small office and home applications, a general rough guideline is to install an antenna for every 1,000 square feet of coverage required.

The number of antennas can be determined more accurately by taking into account the signal clarity and strength at the location of the donor antenna, the type of amplifier being used, and what the space that needs to be covered looks like, i.e. is it big or small, and does is contain walls or is it wide open. Weaker outdoor signal and/or weaker amplifiers normally require more antennas, while an open space needs fewer antennas.

12. Choosing Indoor Donor Antennas for an In-building Booster.

Two types of indoor antennas are generally used - panel and dome antennas. Many cell phone signal booster kits have the option where you can choose the indoor antenna you need.

Panel antennas.

Panel antennas are normally used when:

• On the wall when the space behind the ceiling is inaccessible.
• On the ceiling when multiple floors need coverage enhancement.
• On the wall towards long area when area to be covered is long such as a corridor or a rectangular room that is long and narrow (very long length and very short width).

Panel antennas are designed for wall mounting and the coaxial pigtail normally comes out of antenna's bottom. This means that it is not necessary to make a hole in the wall to connect a cable.

Panel antennas focus signals in a beam that is fairly wide (around 45°). There're however specialty antennas available where the beam is narrow. Due to the type of beam formed by a panel antenna, they are ideal to cover long, thin areas.

Dome antennas.

Dome antennas are normally used when:

• The space behind the ceiling is accessible.
• The area to be covered is large but is not thin and long. For example, a square or oval conference room is suitable for a dome antenna.

A dome antenna's cable comes out of the back of the device, meaning access to the area above the installation point is required. A typical example where dome antennas are used is in office spaces that have removable ceiling tiles. Another application for dome antennas would be in the top floor of a building where the crawl space is accessible, or it has an attic.

A dome antenna distributes signals equally in all directions. If possible, it should be installed in the center of the area to be covered.

13. Summary of Signal Booster Guide.

This guide is quite detailed and could be confusing for those that are not technically minded. Below is a summary of the most important points discussed.

• If you need assistance, feel free to contact us.
• Most voice calls are nowadays made over LTE and don't use 2G or 3G anymore. It therefore makes sense to purchase a cell phone signal booster that supports 4G LTE. The notable exception to this is Sprint.
• The signal bars on a phone don't only show signal strength, but are also an indication of signal quality. Before purchasing a booster, determine both the signal quality (SINR) and the signal strength (RSRP) on your roof.
• Service carriers use combinations of frequency bands in different areas. Buildings are penetrated more easily by lower frequencies (700 MHz & 850 MHz), and it makes sense to focus on amplifying those.
• The cell phone signal booster specifications that are most important specs. are downlink output power and gain.
• Downlink output power is more important when the outdoor signal is strong, i.e. > -70dBm.
• Gain is more important when the outdoor signal is very weak, i.e. < -80dBm.
• The FCC limits the gain and downlink output power allowed for signal boosters.
• Single-carrier boosters may have a maximum gain of 100dB when used in stationary application, and 65dB when used in mobile (vehicle) applications.
• Broadband boosters may have a maximum gain of between 64dB and 72dB (frequency dependent) when used in stationary application, and 50dB when used in mobile (vehicle) applications.
• If outdoor signal is extremely weak (< -105dBm), a single-carrier booster would be suggested.
• For strong outdoor signals (> -70dBm), a broadband (multi-carrier) booster would be suggested.
• Antennas for Outdoors:
• If the signal on the roof is low quality or weak, a directional antenna such as a log-periodic or yagi antenna should be used. Although they are more difficult to install, it is worth the effort.
• If the signal on the roof is both high quality and strong for all carriers that need to be boosted, an omni-directional antenna should be used.
• Antennas for Indoors:
• Dome vs Panel antennas: A dome antenna must be installed on the ceiling, while panel antennas are usually installed on a wall. A dome antenna is used where there is a crawl-space or ceiling tiles, else a panel antenna should be used.
• Providing there is a good outside signal, one antenna should be installed per 1,000 square feet of area that needs to be covered. In buildings with multiple floors, at least one antenna is suggested for installing on every floor.

14. Terminology.

• 3 dB - The dB scale is logarithmic and 3 dB is half the power. Splitters typically have a 3 dB attenuation, resulting in the incoming signal being split in half.
• Antenna gain (dBi) - Although an antenna has an internal gain, it does not amplify signals, but are rather designed to send and receive signals specific directions. The dBi scale is logarithmic. If an antenna has a gain of 0dBi, it does not focus signals at all, while an antenna with 10 dBi gain will receive and transmit 10 times more signal from a specific direction than from other directions.
• Attenuation (in dB) - When signals weaken over distance, or as a result of passing through building material, this is called attenuation which is measured in dB. As it is a measurement of a signal getting weaker, it is typically a negative value, i.e. -10 dB attenuation means a signal that is 10 times weaker, while an attenuation of -20 dB will cause the signal to be 100 times weaker.
• Coaxial cable - Coax. cables consist of a center copper conductor, some type of shielding, plus an outer conductor. Coaxial cable has specifically been designed to carry radio frequency (RF) signals.
• Directional antenna - Unidirectional antennas have a higher gain than others, and focuses on sending and receiving signals in a single specific direction. Two main types are commonly used: log periodic or yagi and panel.
• Dome antenna - Dome antennas are typically installed on ceilings of buildings, and will transmit the signal downwards.
• Donor antenna - These antennas are used in signal booster systems and are placed outside a building or vehicle. Also referred to, as "exterior antenna" or "outside antenna", these external antennae send and receive signals to, and from cell phone towers.
• Downlink signal - This is the signal that is sent from a cell phone tower to a cellular device.
• FCC - The Federal Communications Commission is a government body in United States and it regulates usage of the airwaves and signal boosters.
• Gain (in dB) - Gain measures amplification in dB or decibels. A higher gain signifies a bigger amplification of signals. Gain is measured on a logarithmic scale with 0dB gain meaning no amplification. A 10dB gain will result in a signal that is amplified 10 times, while a 20dB gain gives 100 times more signal, and 30dB gain gives 1,000 times more signal.
• Indoor antenna - In signal booster systems, an internal antenna is installed inside the building or vehicle and is used to communicate with cell phones. It is also referred to, as "interior antenna" or "inside antenna".
• Lightning surge protector - This device protects electronic equipment, including signal boosters in case lightning strikes the donor (outdoor) antenna.
• Omni-directional antenna - An omni-directional antenna typically has slightly lower gain and it sends and receives signals almost equally in all directions.
• Panel antenna - This antenna can be installed outdoors as a donor antenna, or indoors on a wall as broadcast antenna. It transmits and receives signals in the direction it is facing.
• Radio frequency (RF) - These frequencies are used to transmit a wireless radio signal, including WiFi signals, cellular signals and normal FM and AM radio signals.
• Signal strength (in dBm) - Signal strength is measured in dBm which is logarithmic. 0dBm is 1 milliwatt (mW), or 0.001 Watts; 30dBm is 1 Watt; while -10dBm is 0.0001W, or 0.1 mW.
• Uplink signal - This is the signal that is sent from wireless phones to wireless phone towers.

B. Cell Phone Signal Booster Recommendations.

In addition to the popular weBoost & WilsonPro brands, you may consider the following.

3G, 4G, LTE Signal Boosters for Small Home & Office with Good Outside Signal Strength.

3G, 4G, LTE Signal Boosters for Medium Home & Office with Good to Medium Outside Signal Strength.

3G, 4G, LTE Signal Boosters for Large Home & Office with Good to Medium Outside Signal Strength.

3G, 4G, LTE Signal Boosters for Large Home & Office with Medium to Weak Outside Signal Strength.

3G, 4G, LTE, Wi-Fi Signal Booster for Large Home & Office with Medium to Weak Outside Signal Strength.

Commercial Grade: 3G, 4G, LTE Signal Boosters for very Large Home, Building, Office with High Call Volume (Coverage Area Based on Good to Weak Outside Signal).

The Force5 enhances all major carriers and is an alternative solution to a DAS system at a fraction of the cost. Modular in design, for areas over 25,000+ square feet supporting 100+ users.

Industrial Grade: 3G, 4G, LTE Signal Boosters for Extremely Large Commercial Buildings with very High Call Volume (Coverage Area Based on Good to Weak Outside Signal).

3G, 4G, LTE Signal Booster for Vehicles.

Contact options:

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