Wi-Fi: How it works and how it has evolved?

What is Wi-Fi?

This abstract concept, sometimes hard to understand, is actually an evolution of technologies such as radio, satellite TV, and cellular telephony.

Wi-Fi consists of radio signals that travel between two or more points. To function at a basic level, Wi-Fi requires two elements: an AP (access point, which is a combination of radios with antennas) and the device to connect.

These signals operate in three frequency ranges: 2.4, 5, and 6 Gigahertz (GHz).

But what do these numbers mean?

The 2.4 GHz frequency has three usable channels and offers the longest range (meaning it can pass through walls of a house or office). The channels are small spaces within the frequencies dedicated to transmission. A simple way to understand this is to imagine them as phone calls with two or more participants: they won’t hear what happens in other calls (other channels), which are separated to prevent interference.

Due to this limited number of channels, it easily becomes saturated, which is why it's usually not viable to use it on our phones or laptops. However, it works for things that don’t require much speed, like controlling smart devices at home. For example: air conditioners, lights, and other Internet of Things (IoT) devices.

The 5 GHz band is the most commonly used nowadays, with up to 25 channels. Based on how frequencies work, the higher the frequency, the harder it is to pass through obstacles. But what you lose in range, you gain in speed: it is several times faster than 2.4 GHz and reduces interference issues.

Finally, in the 6 GHz range, we find the newest band: it hit the market in 2022 with up to 59 new channels. It shares the same limitations as the 5 GHz frequencies. There are still few devices using it, as only those with Wi-Fi 6E can do so, but it is the option that will lead Wi-Fi networks in the coming years.

How did Wi-Fi 6E come about and what is it about?

This name came about as an improvement in the way we refer to Wi-Fi technologies, also known as WLAN (Wireless LAN).

Previously, we only used what was established by the Wi-Fi Alliance (an organization dedicated to the standardization of its trademarked Wi-Fi, one of the most valued brands in the wireless communications market) and the Institute of Electrical and Electronics Engineers in their standards, which involved naming these types of networks as “802.11” followed by letters that identified the technology (for example, “802.11n”). This made it difficult for users to understand what was best for their connection needs.

In this way, new, more accessible names were created for users:

• Wi-Fi 4 - 802.11n: works on 2.4 and 5 GHz frequencies.

• Wi-Fi 5 – 802.11ac wave 1 and wave 2: works only on the 5 GHz frequency, allowing devices that only support 2.4 GHz to connect to Wi-Fi 4.

• Wi-Fi 6 and 6E – 802.11ax: works on 2.4 and 5 GHz, with the novelty that 6E adds the 6 GHz frequency. This triples the total number of channels available for use. Overall, the main improvement compared to Wi-Fi 5, beyond the channels, is the use of technologies inspired by cellular telephony to manage two-way communication with multiple devices simultaneously. Known by its English acronym as DL/UL MU-MIMO (which stands for download/upload multiple user multiple input multiple output), something that was previously only possible for downloads. This results in lower response time and higher speed for all connected devices.

  
  

Channels and Interference: What Are They and How to Manage Them?

Let’s go back to the analogy of channels and calls. Suppose one person tries to speak at the same time as the other; it becomes complicated or impossible to understand each other. Interference applied to Wi-Fi works the same way: when one transmits, the others stop. This happens in time periods so small (milliseconds) that we don't notice, but the more people need to "speak," the slower and more complex the communication becomes. 2.4 GHz networks suffer the most from this phenomenon with their limited three channels: all of them must be divided into just three "calls."

To avoid interference, it is recommended not to connect to 2.4 GHz networks (when possible), separate the SSIDs (Wi-Fi names) in the frequencies you use to prevent devices from connecting where you don’t want them, and use enterprise-grade equipment (i.e., those for professional networks, like Alcatel-Lucent Enterprise, Meraki, Cisco, Fortigate, or Aruba) whenever you can.

Interference doesn't only come from other networks and devices; if there are multiple access points from the same network transmitting on the same frequency as others, it’s called self-interference.

The Stubborn Devices That Keep Us Up at Night

In Wi-Fi networks, the client (in this case, the device) is king. No matter what you do, if the client doesn’t want to connect to, for example, Wi-Fi 5, there’s nothing you can do but “suggest” that it switches. This is evident, for example, in laptops, which tend to connect more to 2.4 GHz networks than to 5 GHz ones. We see this with Apple MacBooks, while phones and tablets are better optimized and tend to connect to 5 GHz whenever they can.

Additionally, there’s a serious issue between devices known as roaming (switching between antennas), something that phones and tablets do without problems, while laptops remain connected even with weak signals or better connection options. This is referred to as a "Sticky Client."

Just like with interference, one way to manage the connections of these devices is by using enterprise-grade networks, which have better processors and antennas, as well as specific uses (like for outdoor areas). But where they shine the most is in their intelligence to select which channels to use in each location, distribute clients, and suggest, for example, that those reluctant laptops switch antennas or frequencies for a better end-user experience.

This allows us to have specialized networks for warehouse automation or for hotels with hundreds of rooms, working together for the benefit of the customer—something home solutions cannot achieve.

How Can We Improve the Designs of These Types of Networks?

Less is more: when there are limited channels, the more devices you have, the more self-interference you will experience. Therefore, it is always better to place one larger device in a strategic position than to use three or four smaller devices to cover the same area.

Wi-Fi is an essential technology in our daily lives. Understanding these points allows us to make the most of it, from design to daily operation, turning "it should work by magic" into something tangible and real.

By:

Emmanuel Sánchez, Product Line Specialist in Networking & Security.

Emmanuel is a Telecommunications engineer with a diploma in telecommunications management.

He holds international certifications such as Cisco Certified Specialist Enterprise Core (CCNS), Cisco Certified Network Associate (CCNA), Certified Meraki Network Associate, ACFE OmniSwitch, LAN Access Switching, and ACSE OmniAccess Stellar WLAN Enterprise.

In addition, he has completed multiple specializations in areas such as fiber optics, DWDM, SDH, grounding systems, and radio links.