The 802.11 Standards Family
Now that you have a foundational understanding of RF signaling, we can move to the 802.11 standard. When many network administrators hear of 802.11 technology, their mind immediately equates this with the three or four popular wireless networking standards: 802.11a, 802.11b, 802.11g, and the prestandard (at the time of this writing) 802.11n. However, 802.11 describes much more than this when dealing with wireless networks. For example, 802.11e describes quality of service (QoS) standards for 802.11, and 802.11i is an enhanced wireless security standard, to name just a couple. In a way, 802.11 is similar to TCP/IP in that it depicts a suite of protocols and standards.
Of course, in this suite of standards, the most popular are the common 802.11a, 802.11b, 802.11g, and 802.11n. Let’s look at the evolution of these standards.
Party Like It’s 1999: 802.11a and 802.11b
In 1999, two competing standards were released: 802.11a and 802.11b. As with most brandnew standards, vendors did not really begin implementing and releasing equipment that used 802.11a or 802.11b until about 2002. The two standards offered the following features:
It’s an interesting story how these two standards competed. 802.11a was clearly the better standard. It offered faster speeds (54Mbps versus 11Mbps), more channels (23 versus 3), and an overall cleaner RF band (nowhere near as many devices use the 5GHz band as the 2.4GHz band). Alas, the 802.11b standard won the competition (for now) just because it was more available. The silicon used to make the 802.11a chips was in short supply, and the industry was hungry for wireless, so it gobbled up 802.11b instead.
2003 Delivers: 802.11g
After the newness of the 802.11b standard wore off, users and administrators alike demanded more speed. The IEEE answered with the 802.11g standard. This standard borrowed much of the 802.11a technology and implemented it in the 2.4GHz RF band. One of the major hurdles
that was overcome was to achieve backward compatibility with 802.11b, thus allowing 802.11g access points to also support 802.11b clients. For this reason, most access points are labeled as 802.11b/g. Let’s pull the same stats on 802.11g as we did for 802.11a and 802.11b:
The Next Generation: 802.11n
At the time of this writing, 802.11n is currently in prestandard state, set to become a standard in September 2008. Therefore, I will write about the basics of what we currently think the 802.11n standard will become. 802.11n adds multiple input, multiple output (MIMO) technology to wireless cards and access points. Simply put, you now have multiple antennas that can send or receive between devices. This can bring about increased range and throughput.
The irony of the situation is that even though the 802.11n standard is not yet complete, vendors are releasing prestandard devices, placing their bets on what they believe the standard will be. This is quite a risk, because it has yet to be decided which RF band 802.11n will use; it could use the 2.4GHz and/or 5GHz bands. Perhaps by the time you read this the standard will
have been decided. Here is what we currently know about 802.11n:
NOTE
Many vendors are now supplying wireless network cards and wireless access points that support all three (802.11a/b/g) wireless standards. I would expect that the 802.11n standard will obtain similar support before long.