Bluetooth versus WLANs

If asked to construct a wireless local area network (WLAN), most IT managers would think of 802.11b wireless Ethernet technology. Few would consider using another short-range radio technology, Bluetooth, on its own or in combination with 802.11b-based equipment.

The reason for its neglect is that Bluetooth has been marketed as a technology for linking devices such as phones, headsets, PCs, digital cameras and other peripherals, rather than as a technology for LANs.

However, Bluetooth could become a serious WLAN option, partly because a lot more Bluetooth devices will be released over the next 12 months. But IT managers may think twice before supporting this technology ­ because 802.11b and Bluetooth use the same 2.4GHz spectrum to transmit data, interference is a real possibility.

This conflict may lead some IT managers to adopt a cautious approach to Bluetooth on their wireless networks until the standard is better established, said Peter Judge of analyst company Infonetics. "The imminent arrival of Bluetooth is not something that the WLAN suppliers counted on. It must be making a lot of IT managers think twice about installing and relying on 802.11b equipment in areas where there are likely to be lots of Bluetooth devices," said Judge.

The arrival of personal hubs able to handle both types of traffic may provide a solution. Such hubs would sit next to a desktop PC and manage the wired and wireless communication around it. 3Com has a hub system in development. Judge added that it is not yet clear whether Bluetooth will pose a problem. "It's possible that bubbles of Bluetooth activity will be small and therefore not interfere directly with a lot of 802.11b traffic," he said.

Bluetooth is also closing the gap in signal range. TDK Systems is testing a new ceramic antenna that will boost the range of Bluetooth to around 50 metres, up from the 10 metres currently specified and on a par with the maximum range offered by 802.11b components. But TDK, which also manufactures WLAN devices, is hoping it will not be seen as a threat to 802.11b. 'Range is a very emotive and woolly subject,' said Nick Hunn, director of research and development at TDK Systems Europe. 'What's important is throughput. At the moment WLAN easily has the edge, with around 3Mbit/s to 4Mbit/s in practice, compared with about 200kbit/s for Bluetooth. So I think we will start to see Bluetooth in the office for voice services primarily, and 802.11b for data.'

Hunn also stressed that there are options that allow interoperability and migration for the various technologies. He predicted that the huge number of telephone handsets now being sold will give Bluetooth enormous momentum and drive down the price of Bluetooth devices and chipsets faster than their 802.11b equivalents.

Spectralink, a vendor that specialises in voice products for WLANs, was adamant that Bluetooth is no threat. "The Bluetooth camp admit that it is not a network protocol," said Ben Guderian, director of marketing at Spectralink. "Data conflict will be sorted out by the industry bodies involved. IT managers have gone beyond wait-and-see because they know 802.11b WLAN solutions are here today."