Comparing 802.11 Standards

Comparing 802.11 Standards

As mentioned in Chapter 1, "The Basics of Wi-Fi Hotspots," Wi-Fi networks use a technology that is specified within a standard called 802.11. The standard is basically written documents formed by members of the IEEE. These documents help manufacturers develop wireless products so that they will work together with wireless devices from every vendor that follows the standard.

802.11 comes in several versions that have different characteristics, as shown in Table A-1.

Note

It is a frequently misunderstood belief that the actual traffic on a wireless network travels at the maximum or "raw" data rate, such as shown in Table A-1. The actual data rates that users will experience will be much less, up to 50 percent less, due to the normal overhead of the network protocol.

The most widely used standard today is 802.11g, which is similar to 802.11b. However, 802.11g can handle a much greater data rate, up to 54 Mbps. The 802.11g standard is an improved version of 802.11b, in which the main upgrade is the higher data rates, or speeds. The 802.11g standard was created to be backward-compatible with 802.11b. Therefore, it is possible to mix 802.11b and 802.11g devices within the same wireless network. The 802.11a standard, though, is not compatible with these two standards and does not even use the same frequency band.

A drawback to using the 802.11b and 802.11g standards is that they both use the 2.4-GHz frequency band, which has more potential congestion. Other devices such as cordless phones, wireless speakers and headphones, and baby monitors use this band. Microwave ovens also emit radio waves in this range and can cause interference. However, these two standards are most likely the best choice for use in public hotspots because nearly all client devices today implement 802.11g. The 802.11a standard is not widely used throughout the consumer market.

802.11n is an evolving wireless networking standard used for Wi-Fi devices. This upcoming standard plans to use the 2.4-GHz frequency band, as do 802.11b and g, with data rates up to 540 Mbps, which is 10 times faster than existing standards. In addition, these products will have a much longer range by using a powerful smart-antenna technology, called Multiple Input Multiple Output (MIMO), which is already available in some wireless networking products.

Wireless networking vendors have already started selling products based on this technology. The products are referred to as pre-n or 802.11n draft products. With these prestandard components, the user adapter and your AP (or router) must be manufactured by the same vendor.

In addition, even with finalized 802.11n products, both the AP, or wireless router, and the user's wireless adapter have to be 802.11n to achieve all the benefits. Even though it might take a few years for the majority of Wi-Fi users to upgrade, implementing 802.11n (when finalized) for your Wi-Fi hotspot might not be a bad idea, because 802.11b/g users might still receive benefits such as a slight increase in range.

Note

Keep in mind that even though 802.11n might increase tenfold the data rate or speed of a wireless network, typical Internet connection speeds are much lower, such as 3 or 4 Mbps or lower. Therefore, even if the network operates at 540 Mbps, users who are just browsing the web and sending e-mail, such as at hotspots, do not see much of a speed advantage when using 802.11n. However, file sharing between computers on the same private network is much faster for 802.11n users.