802.11 Wireless Standards – CompTIA Network+ N10-006 – 5.3

| May 13, 2015 | 0 Comments


There have been numerous wireless networking standards through the years. In this video, you’ll learn about 802.11a, 802.11b, 802.11g, 802.11n, and 802.11ac network standards.
<< Previous: The TCP/IP SuiteNext: Ethernet Standards >>


The standard for our wireless networks is 802.11. And it’s a standard that is created and maintained by the IEEE LAN-MAN Standards Committee, which is the 802 committee. They have many updates to this standard over time. So you may want to check in with the IEEE and make sure that you’re always reading the latest version of the standards.

The Wi-Fi Alliance is in charge of testing the devices that are created based on these standards. And you’ll find a Wi-Fi trademark on everything that’s passed testing.

One of the very first wireless standards was 802.11a. It was created in October of 1999. And it’s one that use the 5 gigahertz range. It can use some other frequencies if you have special licensing. But generally speaking, 5 gigahertz is where you’re going to see the 802.11a network.

This is one that ran at 54 megabits per second. And because it was 5 megahertz, it tended to have a smaller range than the 802.11b networks that we’ll talk about in just a moment. That’s because these higher frequencies tend to be absorbed by the other things that are around it. And so the signals aren’t able to go quite as far.

It’s difficult to calculate exactly how far a wireless range might be. But a good rule of thumb would be to calculate a third of the range of 802.11b or 802.11g because of this 5 gigahertz absorption.

You don’t really see 802.11a being used anymore. It’s one that is a very old and outdated standard. These days, we’ve upgraded to newer versions of the 802.11 standard. But there might be some very specific-use cases that go back with legacy devices that need to have 802.11a connectivity.

Although it seems like 802.11b would be the next version of 802.11, it actually is not. It’s a version that was created at the same time and released about the same time as 802.11a, in October of 1999.

802.11b works in the 2.4 gigahertz range, which is different than the 802.11a standard. And the speed of this network was also different. It operates at 11 megabits per second. Because it is 2.4 gigahertz, though, you could get more of a range than 802.11a.

The problem, however, is that there are already many devices in the 2.4 gigahertz range. So although you had this 802.11b network, you were also competing with frequencies used by baby monitors, cordless phones, microwave ovens, Bluetooth, and many other devices.

The next major release of 802.11 was 802.11g. This was an upgrade to 802.11b. And it happened in June, 2003. Because it’s an upgrade to 802.11b, it operates also in the 2.4 gigahertz range. However, we are now running at 54 megabits per second. So it has effectively the same speed as 802.11a, although a little bit less throughput because of the signaling that’s used on 802.11g.

But these 802.11g access points were backwards-compatible with 802.11b. So it made for an easy way to upgrade your network from a b network to a g network. But of course, because it was 2.4 gigahertz, you had the same frequency challenges that you had in the 802.11b networks.

802.11n was released in October of 2009. And this update to the 802.11 standard was designed to bring together and upgrade 802.11g, 802.11b, and 802.11a networks. You can have 802.11n operate at 2.4 gigahertz and, optionally, 5 gigahertz simultaneously.

802.11n has a maximum theoretical throughput of 600 megabits per second, a significant increase over the previous standards because 802.11n is using something called multiple-input multiple-output and is using multiple streams to be able to have this kind of high throughput.

The 802.11ac standard was released in January of 2014. And it had a number of significant improvements over 802.11n. One big difference in 802.11ac is that it now operates exclusively in the five gigahertz band. Ideally, you would be able to avoid any of the interference you saw with the 2.4 gigahertz communications.

There is increased channel bonding. So you have additional frequencies and therefore are able to send and receive more traffic through an ac network. It also has a denser signaling modulation, which means that the data transfers are faster over an ac network.

This is able to use eight MIMO streams, which is twice as many as 802.11n. And that gives you speeds of up to almost seven gigabits per second over an ac network.

Here’s a summary of these five 802.11 standards. 802.11a runs at five gigahertz with one of the data streams. And you can have a maximum theoretical throughput of 54 megabits per second. And with that single stream is a single 54 megabit per second throughput.

802.11b is 2.4 gigahertz. Again, one stream at 11 megabits per second. And 802.11g was 2.4 gigahertz. Again, one stream at 54 megabits per second.

802.11n, you could choose between 5 gigahertz and/or 2.4 gigahertz. There were four maximum allowable streams occurring with multiple-input and multiple-output. And at 150 megabits per stream, you have a maximum theoretical throughput of 600 megabits on 802.11n.

And the 802.11ac standard, which runs at 5 gigahertz frequencies only, allows for eight maximum streams, running at 866.7 megabits per stream. That gives you a maximum theoretical throughput of an 802.11ac network at just under seven gigabits per second.

Tags: , , , , , , , , , , ,

Category: CompTIA Network+ N10-006

X