An Overview of Wireless Networking Standards – CompTIA A+ 220-801: 2.5

| November 27, 2012


The 802.11 standard has changed significantly through the years. In this video, you’ll learn the fundamentals of the 802.11a, 802.11b, 802.11g, and 802.11n standards.

<< Previous Video: Common Network ProtocolsNext: Wireless Encryption Standards >>


Review Quiz: An Overview of Wireless Networking Standards

Start
Return
Shaded items are complete.
123
Return


In this video, we’re going to look at a lot of different IEEE 802.11 wireless standards. These standards are maintained by the IEEE Committee for the LAN/MAN Standards, and that is the IEEE 802 section. There are a number of wireless standards they’re changing all the time. And if you want to see what the latest one happens to be, you can always check the IEEE website.

The Wi-Fi trademark you’ll see on Wi-Fi devices. Devices have to go through interoperability testing. There are standards that are set aside just for those devices. And as long as those devices match those standards, they get that Wi-Fi stamp of that logo right on the box or right on the device.

Way back in October of 1999, we received one of the first wireless standards called IEEE 802.11a. 802.11a works in the 5 GHz range and you can also get special licensing to use it over 3.7 GHz at higher power so you can use that particular protocol over very, very large distances. But the vast majority of implementations, especially non-government implementations, are done in the 5 GHz range.

802.11a uses 54 Mbit/s per second as its theoretical maximum speed. And when this first came out, it was very attractive to large organizations that needed that kind of speed in their wireless networks. Unfortunately, it has a smaller range than 802.11b which came out effectively at the same time.

This higher frequency of 5 GHz is absorbed by other objects. And what we found is 802.11a was really best used in environments where it was wide open. Especially warehouses where you needed a lot of high speed networking and there was not much in the way to be able to absorb those signals. If you’re seeing 802.11a today, then it’s probably a very specific use case. These days there are newer standards in wireless networking that tend to make more sense to use than the old legacy 802.11a.

802.11b came out at the same time as 802.11a, but it used a different set of frequencies to communicate. It uses 2.4 GHz frequencies to be able to send that 802.11b signal. It also was much slower when compared to 802.11a, with a theoretical maximum throughput of 11 Mbit/s per second.

That’s obviously much different than the 54 Mbit/s per second that we saw in 802.11a. This had better range, however, than 802.11a. You could have it in a room with a lot of cubes and a lot of offices because the signal bounced around. It wasn’t so easily absorbed by the other devices that happened to be in the building.

But the negative to 802.11b is that there were other devices that use these frequencies. Things like cordless phones and baby monitors are already in place and use those. So you had to be very careful which frequencies you were using with 802.11b, or you would get a lot of interference from existing devices.

In June 2003, IEEE’s 802.11 group came out with a new standard called 802.11g. This is effectively an upgrade to 802.11b, still working in that 2.4 GHz range for devices. So still using those same ranges that 802.11b used, but you were able to go faster. You were able to go up to 54 Mbit/s per second, so it was really about the same as 802.11a. There was actually a little bit less throughput with the g, but effectively about the same throughput for both of those.

One nice part about 802.11g is that it was backwards compatible with 802.11b. So your old 802.11b devices could still communicate to 802.11g access points. You didn’t have to swap out everybody’s wireless adapters all the same time. You could install an 802.11g access point and slowly migrate people to the faster speeds.

Of course, because you’re using the same frequencies, you have the same problems with frequency conflicts that you saw on the 802.11b side. There’s laws of physics that can’t be changed there. If something else is sending out signals in that 2.4 GHz range, it could potentially conflict with the signals that you’re sending on your 802.11g network.

802.11n is one of the newer standards of the 802.11 wireless communication and it was released and made available in October of 2009. One of the advantages of 802.11n is that you have the option to use two different types of frequency ranges or both at the same time. There is a 5 GHz range and a 2.4 GHz range available for 802.11n.

You also get a lot of throughput. There is a maximum theoretical throughput of 802.11n of 600 Mbit/s per second. So that’s a significant improvement over any of the previous 802.11 standards.

This also uses something called MIMO, which stands for Multiple Input and Multiple Output. You could effectively have multiple antennas in your access point all working at the same time. That’s how we’re able to get some of these very, very high throughput speeds, is through the use of MIMO.

Here’s a good summary of these wireless networking types. 802.11a normally runs at 5 GHz. If you get special licensing, you can run at 3.7 GHz. This runs at 54 Mbit/s per second over a single stream and if you’re outdoors, you can run about 120 meters. If you’re using that special license 3.7 GHz range, you can go up to 5,000 meters. That’s why that is a specially licensed range.

802.11b, a 2.5 GHz technology, ran at 11 Mbit/s and also a single stream of traffic and about 140 meters if you’re outside. These are relative distances and your difference may be based on the type of antenna you’re using and the strength of the signal. But it’s something we can use on this slide to help compare the differences between all of these standards.

802.11g– an upgrade to b, so using the same 2.4 GHz range. The speed, of course, now different at 54 Mbit/s per second with that single allowable stream, but about the same distances as 802.11b. And the latest standard of 802.11n runs at 5 GHz and/or 2.4 GHz.

Notice that a single stream runs at 150 Mbit/s per second, but the standard allows you to have up to four streams. That’s how we’re able to get a maximum theoretical throughput of 600 Mbit/s per second. And as you can see, the distance is also a bit farther at 250 meters.

Tags: , , , , , , , ,

Category: CompTIA A+ 220-801

Comments are closed.

X