Reliable WiFi coverage is essential today, yet many users don’t realize what affects signal range and strength. This article explores the main technical and environmental factors influencing WiFi performance, helping internet service providers better understand how WiFi works.

WiFi communications for computer networks is included with every type of mobile device. Mobile devices use the WiFi service, when available, to connect to the Internet. Some examples of devices with WiFi are listed below.

• Mobile phones
• Tablets
• Laptop computers
• Consumer products such as video games and TV’s

WiFi was designed for short-range indoor use. The maximum wireless power of a WiFi device is low with the upper limit set by the government authority. In the USA the FCC sets the maximum wireless power limit for WiFi products.

WiFi has been adapted for outdoor use with all-weather outdoor wireless access points and outdoor WiFi receivers, called client premise equipments (CPE's). The wireless power is low and so the range is limited. An outdoor WiFi installation has a central wireless access point antenna installed at a high point so that it is visible for the people who want to connect to it. The user can then connect a mobile device to the WiFi antenna as shown in the diagram.

The distance between the central antenna and the mobile device must be a clear like of sight. Any obstruction such as a tree or building will block the WiFi signal.

Connecting WiFi devices in a community

The central antenna can be configured for the maximum permitted power, however the distance of communication depends on the device that is connecting to the central antenna. Mobile phones can connect over a short distance only as most phones have a very low power WiFi chip and a basic antenna. Devices such as laptop computers can communicate further as they have a better WiFi chip and a better antenna in the laptop lid. Wireless devices such as the client premise equipment (CPE) can communicate much further due to better wireless circuits and a directional high gain antenna. WiFi communication distances are illustrated in the next figure. The central outdoor wireless access point with antenna can be any one of the following Guest Internet STAR kits, STAR-1, 2, 6, 7 or 8.

The central wireless access point antenna has two important characteristics that describe how the central wireless access point antenna operates. These are listed below

• Point-to-multi-point: This characteristic means that several mobile or fixed devices can access the central wireless access point antenna simultaneously, each mobile or fixed device is sharing the bandwidth available from the central wireless access point antenna and so as more devices connect, the data speed becomes slower for each device. The number of devices that can connect to the central wireless access point antenna depends on its performance. Low cost central wireless access point antennas might be able to connect up to 20 or 25 devices before it is not possible to connect more devices. Expensive but high performance wireless access point antennas might be able to connect between 75 to 150 devices simultaneously. When considering the purchase of a wireless access point antenna the performance must be evaluated to ensure that the product can meet the expectation of the number of users.
• Omni-directional antenna: Most wireless access point antennas that are installed for public Internet WiFi service have an omni-directional antenna. This means that the WiFi signal radiates 360 degrees around the central antenna location. This is illustrated in the next diagram.

Greater distances can be obtained for a much higher cost by installing three wireless access points at the central location, each with a 120-degree sector antenna. This same access point and antenna arrangement is installed on mobile phone operator towers. More information about this configuration can be found in the book referenced at the end of this article.

Connecting a home to the central wireless access point antenna

Readers will be familiar with the process of connecting mobile device such as a phone or a laptop to the central antenna. Homes can also be connected to the central antenna over longer distances.  The reason that a home can be connected to a central antenna over a longer distance is that the home has the wireless client premise equipment (CPE) receiver and antenna installed on the roof. The CPE equipment has a directional antenna that permits a WiFi connection over a much longer distance than can be obtained with a mobile phone. In addition to the CPE received with antenna, the home also requires a wireless WiFi router that will provide WiFi access for the residents in the home. The home installation is shown in the next diagram.

The distance between the home CPE antenna and the central antenna must have a clear line of sight without obstructions.  A tree or building will block the WiFi signal. In addition there must be a clearance around the wireless connection called the Freznel Zone, which is illustrated in the next figure.

The Freznel Zone clearance means that the antennas must be installed above any obstruction such as trees. The laws of physics determine the distance of the antennas above the obstruction, which depends on the frequency used to the connection to the home.

• 2.4 GHz connection to the home: the line of sight between the home and central antennas must be at least 5.6m above the obstacle for every 1Km of distance between the antennas. This means that a distance of 2Km will require a clearance of 11.2m above obstacles. Without the Freznel zone clearance the WiFi communication will not work.
• 5.8 GHz connection to the home: the line of sight between the home and central antennas must be at least 3.6m above the obstacle for every 1Km of distance between the antennas. This means that a distance of 2Km will require a clearance of 7.2m above obstacles. Without the Freznel zone clearance the WiFi communication will not work.
  

Extending the range of WiFi coverage

The WiFi range of the central wireless access point antenna is limited by the devices that connect to the central antenna. The area of coverage can be extended from the central location using a point-to-point WiFi connection, then installing a second point-to-multi=point wireless access point antenna at the end of the point-to-point link. This arrangement is illustrated in the next figure.

The point-to-point wireless link has to follow rules of installation, that include the Freznel Zone clearance which means that the wireless access point antennas have to be installed on tall masts. The installation of a 2.4GHz point-to-point link is illustrated in the next figure. For 2.4GHz the Freznel Zone requires the antennas to be installed 5.6m above obstacles for each 1Km of distance between the antennas.

The 5.8GHz point to point link is preferred as there is less interference in this band, and the bands are larger which means that the data rate between the two antennas can be higher. For 5.8GHz the Freznel Zone requires the antennas to be installed 3.6m above obstacles for each 1Km of distance between the antennas.

Building a community WiFi service

By combining the network technologies described in previous sections, a WiFi network can be designed and built to serve a community. The Internet service is chosen from what is available. A remote rural community will not have access to any type of cable connection and so the only connection available is via satellite. This can be a geo-stationary satellite service such as HughesNet or else a low earth orbit service such as Starlink. A network schematic for a community WiFi Internet service is illustrated in the next figure. 

The design of the WiFi network is the first phase of the community WiFi installation project. Additional information can be obtained from the references in the next section.

Further Reading

This article was written as a response for the most frequent question that we receive from people who are considering a WiFi Internet service for a community,

“What is the range of the WiFi?”

Many people expect that the WiFi range can communicate over many Km and are very disappointed when they discover that the range is a few tens of meters. People expect that the range of WiFi must be the same as a mobile phone service, however there are many differences between the mobile phone service and WiFi.

Some differences of a mobile phone service compared with WiFi are listed below:

• Exclusive licensed frequencies, no interference.
• Lower frequencies that travel longer distances.
• 200x the wireless power output of WiFi.
• Antennas on tall masts for line of sight visibility.
• Three wireless access points with sector antennas per mast for greater range.
• High performance and expensive wireless transmitters and receivers.
• Big cost difference, a mobile phone tower plus equipment costs millions of USD, while a WiFi central antenna costs hundreds USD.

This article provides a very brief introduction to the subject of using WiFi to provide an Internet service. For the reader who wishes to have access to more technical information please download the following book.

How to start a WISP business: (ENGLISH)

NOTE: This book is also available in Spanish upon request.

Contact us today to plan your Internet WiFi community installation.

Guest Internet makes the best products for community WiFi, please contact:

support@guest-internet.com

WISPzone has everything you need to start and grow, please contact:

info@wispzone.com