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.
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:
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.
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).
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.)