I have used the following concepts to help people better understand Wi-Fi who do not have the technical background that many network engineers have. Many people who have attended these presentations are not IT orientated at all, but want to understand why their “Wi-Fi is slow!”

First, a look into the history of Wi-Fi

1000x speed improvement since it´s introduction!

Wi-Fi has come a long way, and if you believe the marketing material, the speed has increased over 1000 times since it´s introduction! It´s important to consider that these speeds are theoretical maximums. Our testing of WiFi 6 indicate that in a typical enterprise, you can reach speeds of up to 400Mbps. This is an improvement over WiFi 5, with measured speeds of 200Mbps. (Speeds are local to the site, and do not account for the internet).

Why the theoretical maximum is so much higher than the measured maximum?

There are a number of reasons why the expected maximum is 6 times less than the theoretical maximum speed. Today we are focusing on 4x topics

  • Our Wi-Fi
  • Their Wi-Fi
  • Capacity
  • Things

All of these topics will be covered using an analogy

Wi-Fi works like a meeting

Wi-Fi works similar to a meeting, in which the access point (or wireless modem) is the meeting host, A channel is the meeting room, and the Devices are the meeting participants.

Defining rules for the example

Our Wi-Fi

Consider a meeting with 2 participants and a single host, with the rules above applied. User A is sitting further away from the host than User B. This means that User A will be speaking louder, and slower than User B. User B must wait for User A to finish talking before they can talk. Because of this, User A impacts the speed of User B.

WiFi is like a meeting room, one person can only talk at once

To combat this, a typical wireless design will introduce Access Points closer to the users (For example, in physical meeting rooms instead of in corridors). The size of the meeting rooms are smaller, done via various techniques. This results in more meeting rooms and more hosts, allowing for users to talk more often – Improving speed.

We add more APs, but there are only certain amount of channels available

It can however, introduce more issues. Adding more Meeting Hosts (Access Points) will add more meeting rooms (channels), and there are only a finite amount of channels available. Eventually you will start having multiple hosts inside a single meeting room.

When 2 APs are audible on the same channel, it is called co channel interference

This is referred to as Co-Channel Interference, and can be depicted like below:

The rule applies, only one person can talk at a time, capacity is halved

The same rules apply, only one meeting participant can talk at a single time when inside the same meeting room. Two meetings are occurring in the same meeting room, participants in both meetings must wait until the other has finished to talk. Capacity is now at least halved.

We combat this issue by encouraging the users to move the the 5GHz network over 2.4GHz. This is because the amount of channels available dramatically increases.

Their Wi-FI

Wi-Fi operates over the air, and the air is a shared space. Often, especially in built up areas (Apartments, Office Buildings), there are many wireless networks operating in the same air.

The result is something similar to the below picture.

This happens even when the APs are managed by different people or companies

The concepts from “Our Wi-Fi” apply here too. We have multiple meetings operating in the same room, across multiple companies – or homes.

Special consideration needs to be taken to combat this issue, often resulting in a site visit to better plan the channels used inside a building. In some cases agreements are made between companies to better use the channels available amongst each other.

Capacity

There are an estimated 22 billion Wi-Fi devices existing today, up from 8.3 billion in 2016. More and more devices are being connected to the internet, and to the wireless. The more meeting participants in a meeting room, the less efficient the meeting – and the slower the WiFi.

5GHz and now 6GHz adds more channels to combat this

This is another reason to move towards 5GHz (and soon 6GHz).

Things

Things are walls, windows, ceilings and floors. Things are also you. 60% of a human is water, and Wi-Fi doesn´t travel well through water.

In the past, wireless was implemented more for coverage than for performance. It resulted in fewer meeting hosts inside a building, and with the meeting being conducted across many different rooms.

Old methodology of WiFi deployments, Coverage over capacity

The meeting participants are talking slowly, and loudly across the home to reach the meeting host. This results in a poor experience for everyone.

A more modern approach is to place meeting hosts in areas where there is a lot more Wi-Fi activity.

New methodology of WiFi design, capacity first

Now the meeting participants aren´t talking through walls to reach to the meeting host.

Finally, there are many things that can interfere with Wi-Fi. For example wireless telephones, controllers, and microwaves. 5GHz is less impacted than 2.4GHz with these things, but issues can still occur. This needs to be analysed through a process called Spectrum Analysis. Spectrum Analysis will monitor the energy in the air and help identify devices, Wi-Fi or not, that are communicating in a given meeting room.

other devices that can interfere with wifi

We have covered 4 topics that can impact the speed of a wireless connection, Our Wi-Fi, Their Wi-Fi, Capacity, and Things. Many other factors exist, including the fact that it is not the Wi-Fi at all, but some other contributing factor (Application slowness, internet speed,,). Hopefully these explanations are helpful for you.

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