Bluetooth joins with UltraWideBandwidth and WiMedia to develop a common architecture

Rethink IT, June, 2005

* The short range wireless technology Bluetooth has always promised more than it delivered, and has been facing death at the hands of the emerging, and far faster, UltraWideBand (UWB) technologies. Now the Bluetooth community is poised to avoid that fate by converging its efforts with those of the leading UWB-based technology groups, and creating a future standard based on a UWB physical layer that will deliver higher data rates to Bluetooth customers, while preserving the advantages that the older spec has, such as its qualification program and brand.

With a similar move mooted for another key short range IEEE standard, ZigBee, there is increasing likelihood that UWB will become the uniform physical layer for personal area networking from digital home networks to PC-peripheral connections and headsets.

WORKING TOGETHER

The Bluetooth Special Interest Group (SIG), the body directing the development and commercialization of the 802.15.1 standard, says it will work with the UWB Forum and WiMedia Alliance to develop the common architecture. These groups are battling to have their respective UWB implementations adopted for the IEEE 802.15.3a standard for high speed connections such as in-home networks--although the hopes of a unifying lower layer based on UWB would be more convincing if only one implementation were in the running. The WiMedia Alliance is also providing the basis for the Wireless USB architecture.

A common physical layer for all these standards would shift differentiation to the upper layers, enabling easier integration of multiple networks within complex environments such as digital homes, while allowing vendors to exploit the strengths of each technology for different applications.

The Bluetooth SIG had already decided, last year, to shift the focus of its efforts in order to broaden its remit, facing a slowdown in its core market, cable replacement for peripherals and headsets. Its roadmap for 2005-6, published in November, put the stress on increasing data rates and improving quality of service, a clear bid for the digital media sector that is the WiMedia Alliance's main target. Bluetooth's chances of playing in this field will be greatly enhanced with the use of the high speed, low power UWB physical layer.

DEFINING SPECIFICATIONS

Work on defining the key convergence layer specification is now underway and should be incorporated in the next major Bluetooth release, in 2006, with volume devices in 2007. Important in the project will be the work already done by the WiMedia Alliance (which merged with the Intel/TI-led Multiband OFDM Alliance) on a software convergence layer to sit on top of the UWB physical and media access control layer specifications. This layer separates the radio from the protocols that use it, enabling multiple applications to share a common radio and providing a route forward for multiple protocols to work with the UWB basic layers.

One such protocol is the Intel-backed Wireless USB, now being developed by the newly formed Wireless USB Promoter Group (WUSB PG), which expects to have a USB 2.0-compatible protocol stack by the end of the year. The WUSB PG is co-operating with the other groups to develop rules that will govern how different protocols share the radio resource efficiently. Bluetooth on UWB could limit interest in Wireless USB, which targets a similar market but it less stable in terms of software and authentication.

Another protocol looking to use the UWB air interface is Firewireless, with the Alliance building IEEE 1394 on top of the convergence layer and MBOA's UWB technology. Now Bluetooth is likely to be one of the protocols sitting on top of the convergence layer and the UWB radio.

Another could well be the low data rate standard, 802.15.4 or ZigBee, which was ratified recently and targets industrial and home control applications. An effort is underway to define an amended PHY based on UWB and this is now an official IEEE study group, called 802.15.4a and led by Staccato and Aether Wire & Location.

PRECISION LOCATION

The key features that must be supported by this PHY are precision location (from within three inches to three feet) and support for colocation of multiple devices. Network scaling up to 1m nodes and the ability to work in noisy, interference-filled environments such as factories, while using less than 1mW of power, are other criteria. Prices must be rockbottom too, for embedded industrial devices--less than $1 for a single-chip product.

Intel, of course, is the common link between many of these standards, being a key member of the MBOA, Bluetooth SIG, WiMedia Alliance and Wireless USB group. For the chip giant, a convergence of all the key short range technologies on a single physical layer could create a vast market in terms of chip volumes, and one over whose core technologies Intel would have a high measure of control.

As UWB puts in its bid to become the universal PHY/MAC under a wide range of communications, it can also build on lessons learned by some of those technologies that may now be consigned to the higher layers. In security, for instance, UWB will incorporate some mechanisms designed for Wi-Fi, and it will also use some of the huge amount of work put into plug and play techniques for USB and FireWire. Authentication--particularly allowing a home device to communicate with other equipment within the home, but not that through the wall in the next apartment--is a key issue. A great deal of work has been done in this area for Bluetooth and so a converged effort could leverage this effort for UWB as a whole, along with other Bluetooth-oriented R&D such as buttons that are pressed simultaneously on two devices to 'introduce' them to each other.