Adding 802.11g to the WLAN

Q: How should 802.11g fit into my WLAN deployment plans?

– Stephen L., Ithaca, N.Y.

A: The IEEE a few weeks ago ratified the latest 802.11 standard, 802.11g, after years of debate and development. Many readers have asked questions about the usefulness and performance of 802.11g, today we will provide some answers.

802.11g is an “amendment” to 802.11b, which itself is an amendment to the original 802.11 standard. The new standard is meant to dramatically increase the throughput of 802.11b networks, while also ensuring backwards compatibility with existing 802.11b products. However, backwards compatibility comes at a price.

First, 802.11g devices use slower modulation techniques and data rates when transmitting traffic so that 802.11b devices can understand them. This adds to transmission times and prevents 802.11g networks from realizing maximum throughput potential.  In fact, early lab tests show that 802.11g devices max out at around 22M or 23M bit/sec. While this is much higher than the performance offered by 802.11b, it is a far cry from the 54M bit/sec that people may expect from 802.11g equipment.

Second, for 802.11g networks to be backwards compatible with 802.11b devices, both must use the same 2.4 GHz frequency. In the U.S., there are only three available non-overlapping channels that can be used for data transmission in an 802.11g environment (other countries may have a fourth channel). That is a relatively small amount of channels – especially considering the fact that radio waves propagate in three dimensions.

Despite these drawbacks, 802.11g should play an active role in your WLAN environment.  It definitely can improve the performance and extend the life of existing 802.11b networks. In addition, when all 802.11b devices are gone, your 802.11g network will no longer be anchored by the burden of backwards compatibility, resulting in a significant performance improvement with little additional investment. 

While this discussion has focused on 802.11b and 802.11g, do not overlook the need for 802.11a in your network environment.  We feel that 802.11a is a necessary complement to 802.11g, providing the same bandwidth and many more channels. In addition, empirical tests show that 802.11a has a comparable range to 802.11g in typical office environments, making it an extremely attractive option. 

The best wizardly advice, therefore, is to look for a WLAN solution that supports all 802.11 bands across a single infrastructure. This will provide the greatest performance and scalability for many years to come.