WLAN Frequency Bands are the frequency ranges used in wireless communcation. Two frequncy bands are used in wireless communication. These are 2.4GHz and 5GHz Bands. Here, we will talk about frequency, hertz terms, frequency bands and human hearing frequencies beside WLAN Frequency Bands. This lesson is also a new lessons in CCNA 200-301.
Hertz(Hz) is the smalles unit used to measure frequency. It is the unit of cyles per second. Frequency is the definion for how often something happens. A frequency of 1 Hertz means that something happens once a second period.
On a piano, note Middle C is 261.65 (262) Hertz. What is this means? This means that when you play this piono button once, every seconds 262 vibrations occurs!
By the way, “Hertz” name is coming from German physicist Heinrich Rudolf Hertz.
There are other higher frequency units. All the frequency units are given below:
Unit Abreviation Hertz
Hertz Hz 1 Hertzh
Kilohertz kHz 1000 Hz
Megahertz MHz 1.000.000 Hz
Gigahertz GHz 1.000.000.000 Hz
By the way human can hear a very low frequency bands if we compare with animals. Human can hear the sounds between 20 and 20.000 Hz. While human can hear only this range;
Dolphins can hear 1000 Hz – 130.000 Hz,
Bats can hear 3000 Hz – 120.000 Hz
Rats can hear 200 Hz – 76.000 Hz
Dogs can hear 15 Hz – 50.000 Hz
Cats can hear 60 Hz – 65.000 Hz
And one of the biggest animals, elephants hears 16 Hz – 12.000 Hz. Lower range than us althought their big ears.
There is a standard frequency range from 0 Hz to 1000…00 Hz (22 zeros). The lower frequencies are too low to hear and the higher ones includes light, X ray, Gamma and cosmic rays.
You can find all these frequency ranges below:
The frequency range between 3 kHz and 300 GHz is called “Radio Frequency (RF)”. Many different radio communication is done on this band. AM/FM radio, shortwave radio, tv,microwave,radar etc. Here, especially microwave band is important form us. Because it includes the frequency ranges, 2.4 GHz and 5 GHz used in Wireless Network Communication.
There are two wireless LAN bands used in wireless LANs. These are 2.4 GHz and 5 GHz bands.
2.4 GHz band lies between 2.400 GHz and 2.4835 GHz, but briefly called 2.4 GHz.
5 GHz band lies between 5.150 GHz and 5.825 GHz, but birefly called 5 GHz.
Beside, 5 GHz band includes below separate bands:
These bands also divided into different channels and each channel is assigned to a frequency.
5 GHz band has 23 separate channels that are not overlap. 5 GHz band has unoverlapping channels. So, using any channel with 5GHz do not affect other Access Points.
2.4 GHz band has 14 channels but each channels of 2.4GHz is too wide, and each channel covers the frequency range of other four channels. So overlapping occurs. Using only channel 1, 6 and 11 avoid overlapping.
2.4 GHz and 5. GHz bands are the two bands used in Wireless LANs. What are the difference between these two bands? Why we use 2.4 GHz? Why we select 5 GHz instead of 2.4 GHz? Here, we will learn differences between 2.4 GHz and 5 GHz.
The most important difference between 2.4 GHz and 5 GHz is speed. 5 GHz is faster that 2.4 GHz. While 2.4 GHz band has a lower speed, it has a longer range coverage than 5 GHz. 5 GHz band has less coverage range.
2.4 GHz has 14 channels and each channel overlaps at least 4 other channel frequencies. So, overlapping can be an issue with 2.4 GHz. 5 GHz band has separate 23 channels. Each of these channels are separate, so there is not overlapping like 2.4 GHz.
2.4 GHz uses long waves and 5 GHz uses shorter waves. So, 5 GHz less penetrate walls and solid places. But, shorter waves prıvide more speed. So, for uploading and downloading 5 GHz is better.
2.5 GHz bans is more crowded that 5 GHz. Old devices, wireless home devices are mostly use 2.4 GHz. So, if you are in a crowded place, using 5 GHz is better than 2.5 GHz.
There are various wireless standards has developed from 1997 to now. These standards has provided a unity in wireless World andcompatibility between different vendor wireless products.
At 1997 IEEE 802.11 was developed and at that time it support up to 2 Mbps data rate and using 2.4 GHz band.
At 1999 IEEE 802.11b was developed and the data rate sjupported up to 11 Mbps by using 2.4 GHz band. Again IEEE.802.11a wa developed in this year and data rate increased to 54 Mbps with 5 GHz band.
At 2003 IEEE 802.11g was introduced and this time 2.4 GHz band also support up to 54 Mbps as before 5 GHz band did.
At 2009 IEEE 802.11n was developed and it support up to 600 Mbps with both 2.4 GHz and 5 GHz. With this standard, High Throughput (HT) was supported.
At 2013 IEEE 802.11ac was introduced and it support up to 6.93 Gbps with only 5 GHz. With this standard, Very High Throughput (VHT) was supported.
At 2019 IEEE 802.11ax was introduced and it support up to 4 Times Faster than IEEE 802.11ac with both 2.4 GHz and 5 GHz. It is the standard of Wi-Fi6.