WLAN Keywords and 2.4GHz Planning

What are WLAN Frequency bands:

WLAN frequency bands are frequency ranges within which we can implement radio waves to enable wireless communication. These frequency bands are implemented and given the various tasks suited for each and for the countries that support each.

The different WLAN frequency bands are also supported by different and in some cases, similar WLAN standards.

WLAN:

This refers to the networking mode of connecting two or more devices via a wireless distribution method. They have high-frequency radio waves traveling through channels and an AP (Access Point) to the internet. These transmission channels are distinguished between overlapping and non-overlapping channels

A spectrum:

This is radio frequency over which wireless signals travel i.e., frequency distribution.

Frequency band: This is the frequency range of a radio wave. A frequency band comprises several channels. Higher frequency electromagnetic waves transmit more power and provide stronger direct radiation capability. However, they support a shorter transmission distance due to quick attenuation during transmission.

A radio wave:

This is also known as a radio, electric wave, or radiofrequency (RF) wave. It can be transmitted and received through an antenna and is normally generated by the alternating current of an oscillation circuit. These are the waves used by WLAN. Radio technology converts sound signals or other signals and transmits them by using radio electromagnetic waves. The frequency of these waves is between 3Hz and about 300GHz. WLAN technology transmits information in space by using radio waves on the 2.4GHz and 5GHz frequency bands.

The radio phase:

This is the distance between the point of origin of any given wave and its first zero crossing. The phase is expressed in degrees or radians and every cycle of a wave spans 360 degrees.

A channel:

This is a path used for information transmission, that is, each frequency range. Several channels from a frequency band.

A radio channel:

This refers to a channel used by radio waves for information transmission in space.

WLAN standards

IEEE 802.11 - 1997 (802.11) - This standard supports a transmission speed of up to 2Mbps on the 2.4GHz frequency band.
IEEE 802.11a - 1999 (802.11a) - This standard supports a transmission speed of up to 54Mbps on the 5GHz frequency band.
IEEE 802.11b - 1999 (802.11b) - This standard supports a transmission speed of up to 11Mbps on the 2.4GHz frequency band. It is also backward compatible.
IEEE 802.11g - 2003(IEEE 802.11g) - This standard supports a transmission speed of up to 54Mbps on the 2.4GHz frequency band. It covers a distance of 150 feet.
IEEE 802.11n - 22009(IEEE 802.11n) - This Standard aims at improving the throughput of the frequency range between 2.4GHz and 5GHz with a transmission speed of up to 600Mbps. It uses several antennae, which in turn increases the data rates.
IEEE 802.11ac wave 1 - 2013 - This is a popular standard on the 5GHz frequency band that supports a transmission speed of up to 3.47Gbps.
IEEE 802.11ac wave 2 - 2015 - This is a popular standard on the 5GHz frequency band that supports a transmission speed of up to 6.9Gbps.
IEEE 802.11ax-2018/19(IEEE 802.11ax) - This is a standard on both the 2.4GHz and 5GHz frequency bands that supports transmission speeds of up to 9.6Gbps.

Overlapping and non-overlapping channels:

Given that radio waves are ubiquitous, random use of spectrum resources will cause endless interference problems. Therefore, in addition to defining the available frequency bands, wireless communication protocols must also divide precisely the frequency ranges. Every frequency range is a channel.

Overlapping channels

Overlapping channels are channels that interfere with each other during transmission. The most common interference occurs between adjacent channels such as channels 1 and 2.

Non-overlapping channels

Non-overlapping channels, on the other hand, do not interfere with each other. Traditionally, only channels 1, 6, and 11 are non-overlapping channels on the 2.4GHz frequency band. When incompatibility is not considered, channels 1, 5, 9, and 13 are non-overlapping channels, given that the standard 802.11b has a bandwidth of 22MHz and has faded out of WLANs.

Distributed among channels, in most countries, the non-overlapping channels on 2.4GHz follow the respective standards: Channels 1, 6, 11, and 14 for the standard 802.11b and channels 1, 5, 9, and 13 for the standard 802.11g/n.

In addition, adjacent channels, such as channels 36 and 40 on the 5GHz frequency band, do not overlap.

2.4 GHz Channel Planning

Even though there are 11 channels available in 2.4GHz, only 3 of them do not “overlap” or interfere with one other: 1, 6, and 11. Channels 2-5 interfere with 1 and 6, while 7-10 interfere with 6 and 11. Without getting too deep on how wireless communication happens, when a station (Access Point, client device, etc.) has something to transmit, it must wait for the channel to be clear. Put simply, only one device can transmit at a time. When overlapping channels are used (2-5, 7-10 in 2.4GHz), any stations (STAs) on those channels will transmit independent of what is happening on the other channels, causing a degradation of performance. This type of interference is called Adjacent Channel Interference (ACI).

Co-Channel Interference (CCI), on the other hand, is when 2 or more AP’s that are in the same area are operating on the same channel. This essentially turns both cells (a cell is the coverage area for an AP) into one big cell. This means that any STA that has anything to transmit now must wait for not only the other STAs associated to the same AP, but also all the STAs associated to the other AP on the same channel. While not as damaging as ACI, CCI will also degrade performance. This is caused by more devices trying to gain access to the wireless medium on the same channel, making STAs wait longer for their chance to transmit.