As you may know, most WiFi devices in use today broadcast information on the 2.4 GHz and 5 GHz bands. You can imagine both of these bands as a highway with multiple lines (channels). As long as there’s at least one empty line, you can safely pass everyone else and reach your destination on time.
2.4 GHz band: In North America, the 2.4 GHz band is divided into 11 channels. Because of its lower frequency, signals in the 2.4 GHz band have a fairly good ability to penetrate solid objects, such as walls and furniture, allowing them to cover a larger range with a strong WiFi signal. In addition to WiFi devices, this band is used by cordless phones, baby monitors, Bluetooth gadgets, and many other electronic devices, all of which can cause interference and slowdowns.
5 GHz band: In recent years, many manufacturers of WiFi routers have released models with support for the 5 GHz band to combat issues with interference on the 2.4 GHz frequency band. Because of its higher frequency, signals in the 5 GHz band don’t penetrate solid objects as well as signals in the 5 GHz band, and they also benefit from a much larger number of available channels. In fact, you can imagine the 5 GHz band as several highways stacked on top of one another, each reserved for different vehicles and divided into multiple lines.
While the 5 GHz band has 24 non-overlapping channels, the 2.4 GHz band has only three non-overlapping channels: 1, 6, and 11.
To make matters worse, not all WiFi routers and their users know that they should be using only non-overlapping WiFi channels because the use of any other WiFi channel is guaranteed to result in adjacent-channel interference.
Why does the use of other WiFi channels results in adjacent-channel interference? Because channels in the 2.4 GHz band have a WiFi channel width of 20 MHz, which would be fine if they were not spaced only 5 MHz apart. As a result, channel 3, for example, overlaps with both channels 1 and 6, and the same is true for channels 2, 4, and 5. Likewise, channels 7, 8, 9, and 10 overlap with channels 6 and 11.
Users sometimes believe that the best WiFi channel is the one that’s used the least, which is why they end up picking an overlapping channel and cause more harm than good. To really find the best channel for WiFi, you need a WiFi channel analyzer or scanner and a little bit of know-how.
In public spaces, apartment buildings, offices, and other densely populated areas, it’s very common for multiple WiFi routers to broadcast simultaneously on a single non-overlapping channel. In such situations, your best option is to use a WiFi channel scanner or analyzer and find the least crowded non-overlapping channel.
To determine which non-overlapping WiFi channel is the best, you need to consider RSSI and noise values. The former stands for “Received Signal Strength Indicator,” and indicates how well a WiFi-enabled device can receive signals from a WiFi router. Noise indicates how much interference caused by other signals affects the particular connection.
RSSI is indicated in negative numbers, and the closer it is to zero the better because zero means that no signal strength has been lost during transmission. For example, an RSSI of -50 is better than an RSSI of -60. With noise, you want to get as far away from zero as possible, so -90 is better than -80.
It’s also very useful to combine the two values and calculate something that’s called Signal-to-Noise Ratio (SNR), a measure used in science and engineering that compares the level of the desired signal to the level of background noise.
To calculate the SNR of a WiFi connection, all you need to do is subtract the value of noise from the RSSI:
RSSI — noise = SNR → (-50) - (-90) = 40
The result is a positive number, and the higher the number is, the better WiFi speeds you can expect.
Now that you know how to calculate the SNR of your WiFi connection, it’s time to switch between channels 1, 6, and 11 and select the one that allows you to achieve the highest SNR.
If this sounds like a lot of work, you need a WiFi channel analyzer like NetSpot, which can calculate everything for you and instantly give you all the information you need to decide which WiFi channel is the best.
After taking a snapshot of surrounding WiFi networks, NetSpot is able to locate the busiest and least occupied channels, helping you decide which channel you should configure your WiFi router to use. To do that:
Use NetSpot to verify that the router is broadcasting on the new channel. It’s useful to try more than one WiFi channel and compare the SNR of your WiFi connection.
In addition to helping you find the best WiFi channel, NetSpot can also perform a comprehensive WiFi site survey, create a detailed WiFi coverage map, help you discover areas of signal weakness, highlight all sources of WiFi interference, and much more.