"Bluetooth cannot be a technology island unto itself," said Andy Glass, Microsoft's Bluetooth technologies program manager, in a presentation at the Bluetooth Developers Conference here. "If the technology does not talk/work with other technologies, we will be limiting ourselves."

By supporting Bluetooth in XP, Microsoft is building a bridge to the technology to expand the scope of its implementation. Microsoft's goal is to build a seamless wireless network where end users can move freely between wireless LAN, Bluetooth, and third-generation (3G) wireless networks without having to reconfigure their PC or understand which network they are roaming into, Glass said.

Microsoft has already announced plans to support IEEE 802.11b radio networks in its XP operating system. By also offering native support for Bluetooth, Glass said Microsoft can provide seamless roaming between both wireless LANs and wireless personal-area networks (PANs).

But the trick to making Bluetooth successful will be to create a good experience for end users. "Bluetooth must be robust and reliable. It's up to us to abstract the technology so it looks like it's a reliable transport to the end users," Glass said. "Personally, I don't trust that the transport will always work. But to the end user, it must look like it always works."

Designers will have to develop software and chips that support seamless roaming, he said.

Chip makers are already working to integrate Bluetooth and 802.11b support on a single device. Cambridge Silicon Radio, Embedded Wireless Devices, Intersil, Mobilian, and others have begun work on baseband chip sets that marry the two technologies.

Microsoft is helping out on the software side. Within its native Bluetooth support, Microsoft will provide a set of software profiles that make it easier to use Bluetooth in a PC environment. Glass said Microsoft will provide native support for the human interface device profile, which will link keyboards and mice to PCs; the dial-up networking profile; a PAN profile; and the enhanced service discovering protocol profile, which allows one system with Bluetooth to discover another in a piconet and determine its capabilities.

Microsoft's turnabout on Bluetooth is a big win for industry, said Simon Ellis, marketing chairman of the Bluetooth Special Interest Group. Microsoft's native support will lessen the pain of implementing Bluetooth and increase its overall acceptance, he said.

Calling IPv6

One implication of Microsoft's vision of an always-connected system is the need for a link between Bluetooth and Internet Protocol version 6. Six million to 13 million Bluetooth chip sets will be shipped in 2001, and that number could grow to one billion over the next five years, Glass said. Each of those devices would require an IP address, Glass said.

The sheer number of addresses will require IPv6, he said. "IPv4 does not provide enough address support," he said. "That's not a good user experience.

Cambridge Silicon Radio is not wasting any time on this front. At the Developers Conference, the Bluetooth chip and software provider announced plans to build an IPv6 profile that it will port to BlueCore, the architecture at the heart of its chip sets.

Widcomm, Open Interface and others are expected to quickly roll out IPv6 profiles as well.

But building profiles may not be an easy task for developers. Glass said that Microsoft's Winsock will be the application programming interface (API) of choice for developing Bluetooth profiles and applications. But Rajiv Kumar, chief technology officer of Widcomm Inc., said Winsock will work fine in some instances but not in cases where Bluetooth devices — some with IP addresses, some without — are communicating on an ad hoc basis or where IP addresses are too costly to implement.

The Winsock API would not be helpful when devices are not exchanging IP addresses, Kumar said. A Bluetooth-enabled headset, for example, would require an IPv6 address under Microsoft's plan. "But if you add IPv6 to a design, that will require an additional 100k of code and add between $1 to $1.50 to a system architecture," Kumar said. And as margins for cell phones and their accessories become smaller, OEMs will have difficulty justifying this additional cost, he said.

Proprietary APIs like the one offered by Widcomm could solve one problem, but create others by using a closed protocol. Widcomm is trying to address this issue by opening its API. Kumar said Widcomm is willing to offer its API to the design community.

But for this approach to succeed, Microsoft would have to accept the Widcomm API as an option for developing Bluetooth profiles. It's too early to know if Microsoft will veer from its Winsock stance.

Test cases

Two chip makers, Cambridge Silicon Radio and Silicon Wave will directly benefit from Microsoft's Bluetooth support in XP. Microsoft has named both as "golden radio" providers, which means their radio chips will be used to help qualify products for Microsoft's Designed for Windows XP Program, formerly known as the Windows Hardware Quality Labs (WHQL) program.

"All radios that want certification must be tested against our [and CSR's] radios," said David Hytha, vice president of Silicon Wave. "By extension, we're automatically qualified." Hytha pointed out that it is too early to officially qualify a supplier, because Microsoft has not set up the test bed.

Microsoft's anointing of the two early adopters of Bluetooth technology could boost both companies, especially with suppliers like Ericsson Microelectronics, Motorola and others competing in the same space.

Robert Keenan is editor-in-chief of CommsDesign.com, an online sister publication of EE Times.