Wi-Fi: How Does It Work and How Has It Evolved?

What Is Wi-Fi?

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

It consists of radio-electric signals that travel between two or more points. To function in its most basic form, Wi-Fi requires two elements: an AP (access point, which is the combination of radios and antennas) and the device to be connected.

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 greatest range (that is, it can penetrate the walls of a home or office). Channels are small spaces within frequencies dedicated to transmission. A simple way to visualize them is to imagine them as a phone call with two or more participants: they will not hear what is happening in other calls (other channels), which are separated to avoid interference.

Due to this limited number of channels, it becomes saturated easily, which is why it is usually not viable for our phones or laptops, although it is suitable for things that do not require much speed, such as controlling smart home devices. For example: air conditioners, lights, and other Internet of Things elements.

The 5 GHz frequency is the most widely used today, with up to 25 channels. Due to how frequencies work, the higher the frequency, the more difficulty it has penetrating 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 most recent addition: it arrived on the market in 2022 with up to 59 new channels. It has the same limitations as the 5 GHz frequencies. There are still few devices that use it, since only those equipped 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?

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

Previously, we only used the designations established by the Wi-Fi Alliance (an organization dedicated to the standardization of its registered trademark 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 meant naming these types of networks as "802.11" followed by letters identifying the technology (for example, "802.11n"). This made it difficult for users to understand which option was best for their connectivity needs.

As a result, new, more user-friendly names were created:

Wi-Fi 4 - 802.11n: operates on the 2.4 and 5 GHz frequencies. Wi-Fi 4 - 802.11n: operates on the 2.4 and 5 GHz frequencies.
Wi-Fi 5 - 802.11ac wave 1 and wave 2: operates only on the 5 GHz frequency, allowing devices that only support 2.4 GHz to connect to Wi-Fi 4. Wi-Fi 5 - 802.11ac wave 1 and wave 2: operates 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: operates on 2.4 and 5 GHz, with the addition that 6E incorporates the 6 GHz frequency. This triples the total number of channels that can be used. In general, the main improvement over Wi-Fi 5, beyond channels, lies in the use of technologies inspired by cellular telephony to manage two-way communication for 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 times and higher speeds for all connected devices. Wi-Fi 6 and 6E - 802.11ax: operates on 2.4 and 5 GHz, with the addition that 6E incorporates the 6 GHz frequency. This triples the total number of channels that can be used. In general, the main improvement over Wi-Fi 5, beyond channels, lies in the use of technologies inspired by cellular telephony to manage two-way communication for 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 times and higher speeds for all connected devices.

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

Let us return to the analogy of channels and phone calls. Suppose that during a call one person tries to talk at the same time as the other; it becomes complicated or impossible to understand each other. Interference applied to Wi-Fi works in the same way: if one device transmits, the others stop doing so. This occurs in periods of time so small (milliseconds) that we do not notice it, but the more participants that need to communicate, the slower and more complex the communication becomes. The 2.4 GHz networks are the ones that suffer this phenomenon the most with their limited three channels: all traffic must be divided among only three "calls."

To avoid interference, it is recommended not to connect to 2.4 GHz networks (when possible), to separate the SSIDs (Wi-Fi names) by the frequencies you use to prevent devices from connecting where you do not want them to, and to use enterprise-grade equipment (that is, equipment designed for professional networks, such as Alcatel-Lucent Enterprise, Meraki, Cisco, Fortigate, or Aruba) whenever possible.

Interference does not only come from other networks and devices; if there are multiple access points on the same network transmitting on the same frequency as others, it is 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. Regardless of what you do, if the client does not want to connect to, for example, Wi-Fi 5, there is nothing you can do other than "suggest" that it switch. This is noticeable, for example, in laptops that tend to connect more to 2.4 GHz networks than to 5 GHz ones. We see this in Apple MacBooks, while phones and tablets are better optimized and tend to connect to 5 GHz whenever they can.

Additionally, there is a significant problem between devices related to roaming (switching between antennas), something that phones and tablets do without issues, while laptops remain connected even with a weak signal or when better options are available. This is known as "Sticky Client."

As with interference, one way to manage the connections of these devices is to use enterprise-grade networks, which have better processors and antennas, in addition to specific uses (such as for outdoor areas). But where they truly excel is in their intelligence for selecting which channels to use at each site, distributing clients, and suggesting that, for example, 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 client, something that consumer-grade solutions cannot achieve.

How Can We Improve the Design of These Networks?

Less is more: when channels are limited, the more devices you have, the more self-interference you will experience, so it will always be better to place one larger device in a strategic position than to use three or four small devices to compensate.

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

By:

Emmanuel Sanchez, Product Line Specialist in Networking & Security.

Emmanuel is a Telecommunications Engineer and holds a diploma in telecommunications management.

He has 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.

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