There have been many 802.11 wireless standards through the years. In this video, you’ll learn about the differences between 802.11a, 802.11b, 802.11g, 802.11n, and 802.11ac.
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Almost all of us have devices that use 802.11 wireless networks. It might be our mobile phones. It might be a tablet. Or it might be the computer or laptop that we’re using. Most of us rely every day, on this 802.11 standard that comes from the IEEE 802.11 Standards Committee. This is one of the most popular wireless technologies in the world, and in this video, we’ll step through the evolution of 802.11 wireless networking through the years.
When the 802.11 standards were released, there were two standards that were released simultaneously. One of these is the 802.11a standard, one of the original standards that was released in October of 1999. 802.11a operated in the five GHz range and gave us throughputs up to 54 megabits per second.
Because 802.11a was using five GHz frequencies, it tended to have a smaller available range than the 802.11b standard. 802.11b uses 2.4 GHz frequencies and those lower frequencies tend to bounce off of other objects, rather than being absorbed by objects at higher frequencies.
The 802.11a standard has been replaced by newer 802.11a standards so you don’t tend to see much 802.11a traffic on a network today.
The 802.11b standard was released simultaneously with the 802.11a standard in October of 1999, and as we’ve mentioned, it uses the 2.4 GHz range to communicate. 802.11b communicated at a maximum possible throughput of 11 megabits per second, which was significantly different than the 54 megabits per second available with 802.11a. But 802.11b gave us effectively longer ranges because those 2.4 GHz frequencies would bounce off of objects, rather than being absorbed.
When challenged with 802.11b and these 2.4 GHz frequencies, however, is there are a lot of other devices that are communicating at that frequency. Cordless phones, baby monitors, and Bluetooth communications all operate at 2.4 GHz and could potentially, create conflicts with the 802.11b communication.
802.11g was introduced in June 2003, and it was very similar to 802.11b. And this is considered an upgrade to 802.11b. It operates in the same 2.4 GHz range, but the overall throughput was increased to 54 megabits per second, which is very similar to the throughput for 802.11a.
This 802.11g standard was backwards compatible with 802.11b so if you installed an 802.11g access point, it could very easily also accommodate 802.11b clients. But you do have the same problem with frequency conflict because you’re still communicating in the 2.4 GHz frequency range.
In October of 2009, we received a big update to the 802.11 standard. This was 802.11n. This was effectively an update for 802.11g, 802.11b, and 802.11a. 802.11n can operate at five GHz or 2.4 GHz. And these particular channel widths of 40 megahertz were much larger than the bandwidths available with previous versions of 802.11.
802.11n can support throughputs up to 600 megabits per second, using this 40 megahertz channel width and four antennas, sending multiple streams of data simultaneously.
802.11n was the first version of 802.11 to use multiple input, multiple output, or MIMO, where you’re able to send multiple streams of information over the same frequency, you just need multiple antennas and radios to be able to send that data.
One of the most recent versions of 802.11 is 802.11ac. This was introduced in January of 2014. 802.11ac operates in the five GHz band exclusively. There are some 802.11ac routers that you’ll see communicating in both five GHz and 2.4 GHz, but all of the 2.4 GHz communication is communicating using 802.11n.
Because there’s no requirement to communicate in the very crowded 2.4 GHz band, you can use much larger bandwidths within five GHz, and 802.11ac supports up to 160 megahertz channel bandwidths.
This ac version of 802.11 can also bond together individual channels to effectively create larger channel bandwidths. There’s also, a denser signaling modulation, which means you can send data much faster. With eight multi-user MIMO streams on 802.11ac, you can, theoretically, support almost seven gigabits per second of throughput on this wireless network.
Here’s a summary of these five standards. 802.11a and b that were released simultaneously. A supported five GHz and b supported 2.4 GHz. And neither of them supported multiple input, multiple output. 802.11a provided 54 megabits of maximum theoretical throughput. And 802.11b supported 11 megabits.
802.11g was an update to 802.11b, and it uses the same frequencies of 2.4 GHz. And it increased the speed up to 54 megabits per second. 802.11n was the very first introduction of multiple input, multiple output. And you could support up to four streams in 802.11n, running at either five GHz or 2.4 GHz. Running up to four of those 150 megabit MIMO streams, you could support a theoretical maximum of 600 megabits per second, with 802.11n.
And with 802.11ac running in the five GHz range, running eight multi-user MIMO streams, you could support almost seven gigabits of throughput over this wireless network.
Category: CompTIA Network+ N10-007