Just as we were getting used to 802.11b wireless LANs and thought we understood the 802.11a variant, along comes 802.11g to confuse us all over again. Deciding which WLAN technology to deploy in the corporate network is now more complicated than ever, though there are signs that the mists of confusion will lift in the future.
The bandwidth offered by the three standards - 802.11b, 802.11a and 802.11g - is less of an issue than the different radio frequency wavebands - 5GHz for 802.11a, and 2.4GHz for 802.11b and 802.11g.
The two radio wavebands are referred to as licence-exempt, which means that companies do not need to apply for a radio licence to use them, but must comply with the rules about power levels and channels set out by the Radiocommunications Agency.
So, how do IT managers decide which of these wavebands to choose? From the radio point of view, there is less signal interference, and therefore perhaps more reliability, in the 5GHz band. The 2.4GHz band is used by other radio equipment, including Bluetooth devices, Dect phones and microwave ovens.
Many say that signal range in the 5GHz waveband is lower because of the higher data rate. In truth, most users probably won't notice this because higher power is permitted to boost the signal and the systems will almost always be operating well below maximum range anyway.
Another factor is that 5GHz equipment has only been available for a short time and is generally more expensive than 802.11b kit. This may not be a problem for some, but most companies will want to allow cheaper, legacy 802.11b network adapters and PC Cards to be used on the WLAN for less demanding applications.
It is, of course, possible to have two sets of access points, one for each waveband, but this may be expensive and difficult to plan and manage. However, there are a few suppliers of dual-band access points covering 802.11a and 802.11b and these may offer the solution.
But what about 802.11g? First of all, the standard for 802.11g is not scheduled for final agreement until July 2003, so early adopters should be wary of buying kit before then or should make sure their suppliers will upgrade to the final specification at no extra charge. 802.11g uses the same 2.4GHz waveband and power levels as 802.11b, but at about five times the data rate, so its range is likely to be less. In that case, why bother with it at all?
What is certain is that 802.11g will be heavily promoted because it allows vendors to build on the technology and hardware base they have developed for 802.11b, even though the evidence suggests it is inferior to 802.11a in many respects. Consequently, 802.11g equipment will fast become more plentiful and probably cheaper.
Given a greenfield installation and not too many budgetary constraints, 802.11a is the best all-round choice for IT managers. 802.11b users will be excluded from the system but dual-band access points provide a solution if 802.11b users also need to be supported on the WLAN. In the future, dual-band units will also be able to support 802.11g, but I would be surprised if any of the units available today could be upgraded.
reader comments