Bluetooth PANs the Wireless LAN

2000-10-11

The arrival of Bluetooth, the short-range wireless communications standard, is moving ever nearer. Products are not due until the latter half of this year but the announcements are now coming thick and fast, with the IT majors now joining forces with the technology providers to make it happen. At the end of last week, for example, IBM announced it was partnering with TDK to develop Bluetooth solutions for its Thinkpad range of laptops. Despite the fact that TDK is not known as an IT company, it has carved itself a niche as a producer of networking devices that meet the standard formerly known as PCMCIA. Back in 1998 TDK was quick to pick up on the potential of Bluetooth, and has been supporting standards work and developing products ever since. IBM, too, has been an active proponent of the technology but has recently been pulling back from the production of networking devices. The result: IBM has a partner that can deliver, and TDK has a conduit for its products to die for.

The principle behind Bluetooth is simple. Devices broadcast a wireless “hello, I’m here” into the ether and listen out for any responses. Should one device detect another, the two will form a loose network, known as a Personal Area Network or PAN. PAN clusters can then form into a kind of super-PAN using hub units that act as a switch between different PANs. The active range of Bluetooth is ten metres: the intention is not to replace existing LAN technology but more to enable locally positioned devices to interact, for example a PC with a printer or a mobile phone with a PDA. If the standard had anything in its sights, it would be the infra-red standard IrDA but Bluetooth is primarily an innovation – it augments existing facilities rather than replacing them.

This is all well and good, but (and there is always a but) Bluetooth isn’t the only wireless technology on the block. There are a number of vendors who are indeed setting their sights on the LAN. These include Apple, which has already released its own wireless protocol. Most likely to succeed is the wireless Ethernet standard, behind which a consortium of vendors is already lining up. However, through the fault of nobody in particular, Bluetooth is proving to be the fly in the wireless ointment. The two wireless standards can, and do, interfere with each other making it difficult to run both PANs and wireless LANs.

Steps are being taken to minimise the damage. Symbol Systems, for example, has included frequency-hopping in its 2Mbps wireless LAN technology so that if interference is detected, it can be countered. This has all the hallmarks of a workaround, and apparently it does not work for higher data speeds. The current advice is not to use the two in the same part of a building: clearly this is not a rule which builds confidence.

Where to go from here? Data communications experience suggests that, when two or more protocols get together, some bright spark designs an interface between them. It may be that if wireless LAN devices can also talk Bluetooth, both standards can exist in the same frequency range. Ultimately the question arises whether more than one wireless protocol is necessary at all: time will tell but, even though the standards do not overlap in principle, it may prove unwise to focus too heavily on one technology.

(First published 11 October 2000)