802.11 Wireless Standards – CompTIA A+ 220-1001 – 2.4

| December 15, 2018


The evolution of wireless technologies includes different frequencies, speeds, and features. In this video, you’ll learn the specifics of 802.11a, 802.11b, 802.11g, 802.11n, and 802.11ac.

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There are a number of different standards associated with 802.11 networking. These standards are maintained by the IEEE LAN/MAN Standards Committee for the IEEE 802, and this is specifically the 802.11 standard. There have been many updates to 802.11 over time. New standards and changes are happening all the time. You can check the IEEE’s website to find out what the latest innovations are around 802.11.

If you ever see a device that says its 802.11 compliant, then it’s had to go through interoperability testing. There’s a Wi-Fi trademark on the box that shows that the device has gone through testing, and should interoperate with all other devices that have gone through the same testing. 802.11a a is the first of these 802.11 standards that was introduced. It was made available in October of 1999. It’s a standard that operates in the 5 gigahertz frequency range, and it operates at 54 megabits-per-second.

Because 802.11a and 802.11b came out at exactly the same time, there are a lot of comparisons as to how these two standards operated. 802.11a, because it operated at 5 GHz, had a little bit smaller of a range than 802.11b. These higher frequencies are absorbed by objects that are around them. So in a normal environment, you could see about a third the range with 802.11a compared to other 2.4 gigahertz frequencies, like 802.11b or 802.11g.

Since 802.11a was one of the very first standards, it’s one that has also been updated through the years, so you don’t often see 802.11a devices being used any longer. The 802.11b standard was introduced at exactly the same time as the 802.11a. And unlike 802.11a, 802.11b operates in the 2.4 gigahertz range and has a maximum theoretical throughput of 11 megabits-per-second. You can see this is quite different than 802.11a that had higher frequencies but operated at 54 megabits-per-second.

Although 802.11b was a bit slower, the tradeoff was that it used the 2.4 gigahertz frequencies that tended to have a longer range than 802.11a. One of the challenges with engineering an 802.11b network, though, was other devices were also using these frequencies. Devices such as baby monitors, cordless phones, microwave ovens, and other devices used exactly the same frequencies that needed to be used by 802.11b.

In June 2003, we got an update to 802.11b. This was the 802.11g standard. This also operated in the 2.4 gigahertz range, and very similar to 802.11a, we had an increase in speed up to 54 megabits-per-second. This 802.11g standard was designed to be an upgrade and to be backwards-compatible with 802.11b, but it had the same 2.4 gigahertz frequency conflicts that we saw with the 802.11b standard.

In October of 2009, we saw an update to 802.11a, b, and g with the standard 802.11n. This was a standard that allowed connectivity at 2.4 gigahertz range frequencies or 5 gigahertz range frequencies. And we were able to get throughputs with 802.11n up to a theoretical maximum of 600 megabits-per-second. One of the ways we were able to get these larger bandwidths was through a technology called multiple-input multiple-output, or MIMO. We’re able to send many streams of traffic across the same frequencies to increase the total amount of throughput on an 802.11n network.

One of the latest versions of wireless technology is the 802.11ac standard. This was an update to 802.11n and it added a number of additional features and additional throughput. This operates in the 5 gigahertz band exclusively. There are no 2.4 gigahertz options for 802.11ac. The 5 gigahertz range has a much larger set of available frequencies, so we’re able to bond channels together and get higher throughputs from 802.11ac. 802.11ac was also made faster by changing the modulation. We’re now able to send more data in the same amount of time.

And there were also improvements over the multiple-input multiple-output technologies we saw with 802.11n. 802.11ac introduced multi-user MIMO, so you could have eight separate MIMO streams going to multiple devices on the network, all at the same time.

Here’s a summary of these five wireless standards. 802.11a operates at 5 gigahertz frequencies. It did not support multiple-input multiple-output streams, and had a maximum theoretical throughput of 54 megabits-per-second. 802.11b operates at 2.4 gigahertz, has a maximum theoretical throughput of 11 megabits-per-second. 802.11g upgraded 802.11b, so it also ran at 2.4 gigahertz frequencies, and has a maximum theoretical throughput of 54 megabits-per-second.

802.11n can support 5 gigahertz and 2.4 gigahertz frequencies, and with the addition of four MIMO streams, you’re able to extend the 150-megabit throughput on a single channel, up to 600 megabits-per-second total. And 802.11ac operates in the 5 gigahertz frequency range, supports a maximum of eight multi-user MIMO streams, which means our total maximum theoretical throughput for 802.11ac is almost 7 gigabits-per-second.

Category: CompTIA A+ 220-1001

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