Wireless Alphabet Soup – 802.11 A, B, G, N

I’m writing this quite quickly, so if it’s not clear or contains mistakes, please let me know. Your comments are always very welcome.

Overview

Wireless networks (“Wi-Fi”) operate using a set of standards named 802.11. These standards are suffixed by and better known by a letter: 802.11a, 802.11b, 802.11g, and 802.11n. The latest and fastest technology is 802.11n (or N), which offers huge speed and range boots over its predecessor, 802.11g (or G).

Wikipedia explains the basic comparison well:

802.11a: “…operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s [6.75 MB/s], plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbit/s [2.5 MB/s].

802.11b: “…has a maximum raw data rate of 11 Mbit/s [1.38 MB/s] […] 802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones.

802.11g: “…works in the 2.4 GHz band (like 802.11b) […] It operates at a maximum physical layer bit rate of 54 Mbit/s [6.75 MB/s] exclusive of forward error correction codes, or about 22 Mbit/s [2.75 MB/s] average throughput.

802.11n: “…operates on both the 2.4GHz and the lesser used 5 GHz bands. […] Prior to the final ratification, enterprises were already migrating to 802.11n networks based on the Wi-Fi Alliance’s certification of products conforming to a 2007 draft of the 802.11n proposal.

Some important points not discussed above about 802.11n:

Frequency

Some N wireless access points (AP) operate only on 2.4 GHz, others force you to choose between 2.4 and 5 GHz, while the best operate on both band simultaneously.

The 5 GHz band is preferable because it’s relatively clear of interference. You can’t enjoy this benefit if you buy a 2.4 GHz-only N AP. You also can’t enjoy this benefit if you buy a selectable 2.4/5 GHz model but need to support G devices. In order for the G devices to connect, you will be forced to run the AP in 2.4 GHz mode.

If you face a lot of interference (perhaps you live in a condo or apartment) or need to mix G and N devices, your best bet is a dual-band AP that operates on both frequencies simultaneously. Also note that some N devices, such as the Apple iPhone 4, are 2.4 GHz devices that can’t connect on the 5 GHz band.

Throughput

The best consumer N APs I have seen offer a theoretical maximum of 300 Mbit/s (37.5 MB/s). Real world results might be around 100 Mbit/s (12.5 MB/s). You should keep in mind that even my upgrade Shaw Extreme Internet pretty much never exceeds 30 Mbit/s [3.75 MB/s] and only promises 15. A fast wireless network won’t make your internet connection any faster. The speed differences become apparent when you need to move data around between devices on the local wireless network (e.g. between your laptop and your desktop).

Draft-N Devices

If you look closely at the fine-print on wireless N AP boxes in your local retailer, you may notice some mention being “draft N“. This means they were released prior to N being finalized. My experience of the DLink DIR-655 draft N AP was that it lacked compatibility with the MacBook Pro and I had constant dropped connections and couldn’t get good performance. I had to replace this device (I chose the Linksys E3000 in part because it, like the MacBook, is based on a Broadcom’s N implementation).

Draft N devices should be software upgradeable to the full N spec, but since DLink hasn’t done this for the DIR-655, I wouldn’t count on it. You’re better off looking for a proper N implementation.

Buying a New AP

While N APs are quickly becoming the only option, you are still likely to be able to find some cheap Gs that retailers are looking to clear stock on. If you have only G devices, you should consider passing over that cheap AP in favour of an N. Why? Because odds are good that you’ll acquire an N device in the next year or two and want to enjoy the benefits of N: a faster local network, better range, and less interference on the 5 GHz frequencies. Don’t worry, though. If you own or choose a G AP, your N devices will fallback and use G instead. (It is possible to disable G on an N AP, but by default they operate in “mixed” mode and support multiple standards.)

Advertisements

About Fergus

Fergus likes to invent cool titles for himself, such as “Communications Specialist” or “Internet Architect”. What it really comes down to is that Fergus’s passion is internet communication. He believes that helping people communicate more effectively makes the world a better place. To this end, he seeks opportunities to help individuals, businesses, and non-profits to communicate their ideas, products, and services beautifully. Some examples of the types of work Fergus undertakes: web design, graphic design, programming, and search-engine optimization. Fergus also enjoys consulting with people about their existing web sites and strategies as well as their plans. Fergus doesn’t enjoy writing about himself in the third-person quite as much, but sometimes it seems a necessary evil.
This entry was posted in Networking, Wireless Networking and tagged , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s