Viewpoint: WLAN upgrade dilemmas

Firms should not deploy 802.11a wireless LAN equipment until they are sure the Radiocommunications Agency (RA) has approved kit for use in the UK. Even then, IT managers may benefit from staying with 802.11b for the time being while planning to evaluate 802.11a kit and perhaps roll it out next year. If possible, firms may want to wait for the modified version of the 802.11a standard, known as 802.11h, which should be ratified in late 2002 or early 2003 and will have pan-European approval.

One reason that firms may want to turn to 802.11a early is if they operate high-density WLAN environments that support many users. Alternatively, they may need lots of wireless bandwidth for specific applications, such as computer aided design (CAD). Either way, IT managers wanting to deploy WLANs need to talk to vendors about strategies to upgrade from 802.11b, and they should carefully plan the layout of their networks, because a lot more access points are needed in order to exploit the potential of 802.11a.

Many people assume wrongly that 802.11b will die overnight when 802.11a arrives, but 802.11b sales are still growing which means the equipment will get cheaper. In addition, 802.11b has better power management and uses less battery power, increasing its attraction for notebook and handheld PC connectivity.

There is no doubt that WLAN security is a weak point, but it is being addressed and better encryption should arrive soon. There is a danger of data transmissions being intercepted, and there are other areas where WLANs can be vulnerable.

For example, there are issues with rogue access points and peer-to-peer network sharing, but WLANs can be made fairly secure if IT managers do the right things to avoid problems.

In some instances where Bluetooth wireless connectivity is used in close proximity to 802.11b kit, there may be some interference in the 2.4GHz waveband. WLANs may suffer due to collisions forcing errors and repeat transmissions, which may reduce throughput and hamper voice conversations.

Fixed line carriers such as BT may regard the provision of public access hotspots as an opportunity to get back into mobile networks. BT's plan to create up to 4,000 of these public-access WLANs by 2004 is the first in Europe, but other carriers may follow.

A number for companies are working on ways to allow better handover between WLAN access points and other types of wireless network.

Nokia has shown that a GSM roaming mechanism can be used in WLANs by putting a smartcard into the access point, for instance. Others companies are looking at ways to allow WLAN or Bluetooth devices to roam cellular networks.

Nigel Deighton is vice president for mobile services at market research company Gartner.

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