exclusive content published on August 20, 2006

Wi-Fi (802.11x) networks have been around long enough that many businesses and home users run their own. The first widely deployed standard was 802.11b, while most new hardware uses 802.11g. The latest 802.11n hardware is just around the corner. If you run an existing wireless network, is it time to upgrade?

The spirit of radio

The IEEE 802.11x networks use radio signals to move packets. Both 802.11b and 802.11g use the 2.4 Gigahertz frequency, also used by wireless phones and other appliances. The main difference between the two is the data rate: 11 Megabits per second for 802.11b and 54 Megabits per second for 802.11g. Real world throughput is about half the data rate.

Some vendors released 802.11a hardware but it was not a commercial success. The 802.11a standard runs at 5 Gigahertz, but has the same 54 Mb data rate as 802.11g.

The b, g, and a standards all have an indoor range of 30 meters.

The new buzz is around 802.11n, running at 2.4 Ghz and theoretically offering a 540 Mb/s data rate (200 Mb/s actual) and an increased range of 50 meters. It achieves the increased data rate by using multiple transmitter and receiver antennas. At the time of this writing, the n standard was not finalized. However, several vendors have released pre-n hardware based on the current version of the spec.

Generally, I don't buy hardware that is released before the spec is finalized or has proprietary vendor modifications. For example, many wireless access point vendors offer hardware that supposedly doubles the standard data rate of 802.11g. However, their super-duper fast implementation only works with their brand of super-duper adapters, locking you into their hardware to achieve that data rate. Don't fall into that trap.

Costs and Collisions

If you are thinking about upgrading your Wi-Fi network, remember that you may need to replace your access point and your client adapters in order to benefit from a faster spec.

Unlike most wired ethernet hardware, wireless is not "switched", making it subject to traditional CSMA/CA collision degradation as it gets busy. It is similar to a shared hub in that respect. A paper at Spread Spectrum Scene describes the access method in detail.

If you are currently operating a b network and things are working, do you really gain much from upgrading to g? In many situations, the answer is no. If you mainly use your network to access the Internet, the performance bottleneck is likely to be your Internet connection, not your wireless network. This is especially true if you don't have a high speed connection (cable modem, DSL, etc.) Even if you do, speeding up the last 30 meters might not be noticeable. On the other hand, if you want to copy large files around your local LAN or stream video to your TV, an upgrade to g would be a big help.

I ran a non-scientific test using the CNet bandwidth meter speed test page from the same computer using both b and g wireless connections, and a wired 100 Mbps ethernet connection. The b card was an Orinoco Silver, the g card was a D-Link DWL-G650 (Atheros), and the wired card was a Realtek RTL8139. All used the native Linux drivers in Fedora Core 5. The access point/switch was a Netgear WGR614.

My Internet connection went through a high speed cable modem. The numbers are the average of three downloads from Firefox (clearing the browser cache each time).

802.11b	802.11g	100 Base-T
2057 Kbps	2369 Kbps	5042 Kbps

There was only a 15% increase in throughput from b to g. Traditional wired fast ethernet more than doubled the performance of g. One variable not accounted for in the numbers is variation in driver quality. What's most important though is the real world performance of the hardware/driver combination.

Security

Security features aren't really tied to the Wi-Fi speed or frequency (a,b,g), but are related to implementations of the 802.11 security specs. Most current hardware uses Wi-Fi Protected Access (WPA), an improvement on the original Wired Equivalent Privacy (WEP) security mechanism. The best security to date uses the WPA2 specification (802.11i). Higher end hardware supports WPA2. Some access points offer MAC address authentication. The additional layer of protection is useful, but not unbreakable.

Given the track record of Wi-Fi security, I don't rely on it. Instead, I rely on SSH to encrypt the data stream.

Summary

The cost difference between b and g hardware has almost disappeared, so if you are buying everything new, g is the way to go. If you need to move a lot data around your local network over wireless, an upgrade to a g network can really help. If you mainly use wireless for Internet access and already have a working b network, wait for n to stabilize. If security is the most important issue, then upgrade all equipment that is not compliant with WPA2.

Here is a summary of recommendations depending on what hardware you currently have and how you plan to use your wireless network.

Current hardware	Network application	Recommendation
none	Internet or LAN (moving big files)	buy 802.11g now
802.11b	Internet	wait for 802.11n
802.11b	LAN (moving big files)	buy 802.11g now
802.11a	Internet or LAN (moving big files)	wait for 802.11n
802.11g	Internet or LAN (moving big files)	wait for 802.11n
802.11a/b/g	Best security	buy 802.11g with WPA2

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