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How to Plan a Basic Cellular Repeater System Design

September 18, 2018

In Building Cellular Amplifier Installation Guide

Free Downloadable Guide

With 77 percent of the population owning a smartphone, reliable cellular signal is no longer a luxury, but a necessity. No matter the industry or location, the employees, tenants and visitors to any type of building expect to be connected. And they expect to be able to do much more than simply call and text on their devices.Still, there are a number of places where either remote location, environmental or building materials impede cellular signal. As an integrator, your customers rely on you to execute a plan that will improve service at their facility where they need it most. Although at times, planning a basic system design can be a challenge. In this article, we’ll take a look at some of the basic components and considerations you can’t afford to overlook when planning a basic system design.

Start with a site survey

Any cellular signal amplifier installation should begin with a thorough site survey that includes obtaining an accurate outdoor signal reading with a proper signal meter. A signal meter is an integral part of setting up a signal amplifier because it allows you to view the entire cellular spectrum for all carriers.You’ll also need to obtain a complete blueprint or floor plan of the space from the building owner and conduct your own thorough walkthrough of the site. With that information in hand, you can create a simple layout in the form of a flowchart to help you better plan and ensure that you don’t overlook any components of the design.From there, you can employ layout software into your design, which will assist you in determining what you will need. For example, you can use applications such as Microsoft Visio, Publisher, or iBwave, which has the built-in Wilson component to help you run all of your mathematical equations. This will help you to determine how much cabling you will need.Once you have completed a valid site survey you should have collected the information you need to begin to determine how various factors will impact the system design, such as:

Outside signal strength
The size of the building’s exterior
Ideal locations for mounting antennas
Cable penetration points
Interior wall and surface materials
Prime amplifier installation locations
Where you anticipate running cable and how accessible these areas are
Where to mount broadcast antennas
Anomalies or unique building specifications that will impact the design requirements

Identify obstacles

Once you’ve obtained available signal readings, the next step will be to measure and identify internal obstacles, such as drywall, concrete beams, multiple levels, and energy-efficient windows, for example, which can all hamper signal and signal boosting. It’s important to consider all of these factors because, while one antenna can cover a large area inside if there is strong enough signal, each of these components can affect the efficacy of that antenna.These factors will be critical to calculating signal loss within the building and accounting for it in your final system design. If, for example, you have a 4,000-square-foot facility and it’s all open space, such as an empty warehouse, one antenna in the center would cover that entire building.But when there are interior walls and other factors, you will begin to experience loss and will benefit from adding antennas into your design.

Determine how many antennas are needed

Once you’ve looked at the blueprint and taken the site survey into account, you can begin to plot the number of antennas that will be necessary in each zone of the building. It’s important to consider the maximum antenna recommendations for each amplifier, too. For example, with the Pro 1000, 70, and 1050 series, the maximum recommendation is four antennas. If you find that you need more than that, you should consider adding more amplifiers or moving up to a more robust amplifier, such as the Pro 4000, which is scalable to a larger coverage area.The choice of the antenna should be based on the desired area of coverage. It’s very important to remember that adding antennas doesn’t add square footage, but additional antennas can be added to avoid attenuation obstructions such as walls, beams, or shelving.

Determine type and number of amplifiers

After you’ve nailed down the number of antennas, then you can better determine the type and number of amplifiers needed. Outdoor signal strength is a key determining factor here. In a weak signal environment you would add fewer antennas to the amplifier output than you would in a strong signal environment because the output power of the antenna could not afford the additional attenuation that the splitter would cause to add antennas.When selecting an amplifier, the “magic” number is right around -45 dBm for an outdoor reading. If the signal coming into the system is -45 dBm or stronger on any frequency band, this can cause the Pro 70 series amplifiers to shut down those bands. Both the WilsonPro 4000 and 1000 series feature automatic gain control (AGC) and extended dynamic range (XDR) features, which are built into the software of the amplifier to attenuate the signal to a usable range that meets FC requirements and won’t shut down any bands.

Determine signal gain or loss

After you’ve selected the equipment and parts you will use, you must then figure out the amount of system loss and gain in your proposed design. Building materials and obstructions as well as the amount of cabling and splitters needed, will all contribute to signal loss. Therefore, you want all of your cabling to be as short as possible while maintaining coverage.Signal gain, of course, is achieved from the amplifier and external and internal antennas.Those two equations together will give you your loss budget and your total system gain. Ideally, you want to place your external donor antenna as close in proximity to the amplifier as possible and in the most centralized location.

The role of outside signal readings

Outside readings are arguably the most important component in designing a successful cell booster system.To obtain an accurate outside reading, take your cable length and subtract the loss of the cable from the outside antenna to the amplifier. This will help you accurately determine gain and loss from the cable to the antennas. Be sure to account for any splitters added and their respective loss values.When you’re dealing with decibel measurements, it’s a simple addition and subtraction equation. You can add or subtract to figure out the value and then convert dBm to an actual percentage of gain or power output, depending on what you want to look at.For example, if you have a -20 dBm output at your antenna, you have the ability to cover about 4,500 square feet of unobstructed space.

Set customer expectations

Once you’ve conducted your complete assessment of the available signal and the space, it’s critical to begin setting customer expectations. This begins with communicating to the customer that the signal improvement that is achieved indoors depends upon the strength of the signal that exists outdoors.Then you can begin to consider which type of amplifier is best suited to the project and discuss that with the customer as well. WilsonPro offers several different options, from the Pro 70 to the Pro 4000, which work best for different sizes of buildings. You will need to educate the customer that the amplifier used will determine the maximum signal output, regardless of outdoor signal. For example, if the system design calls for the Pro 1000, there will be a maximum output of 15 dBm.Designing a booster system is a subjective process to some degree and there is no absolute right or wrong configuration. Ultimately, it comes down to the outside signal that is available.There are multiple components involved, from the initial site survey to the final design, and setting your customer’s expectations. You never want to over promise or misrepresent your capabilities. It’s always best to over-deliver.Your ultimate goal is to reproduce or improve the optimal existing environment and make that signal accessible and useful indoors. Remember, signal can only be improved if there is existing outdoor cell signal to amplify.If you’d like to learn about becoming a WilsonPro-certified system integrator, contact us today.

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