Bluetooth Update: More Speed, Less Power

Manhasset, N.Y. — In an attempt to dispel concerns about the technology's future, the Bluetooth Special Interest Group this week will unveil its road map out to 2006. The document, which emphasizes higher data rates, lower power, improved security, quality-of-service and an accelerated qualification program, cements Bluetooth's position in headsets and automotive applications while opening opportunities in industrial sensors and home automation and security.

Much of the skepticism concerning Bluetooth derives from a protracted gestation period and initial pressure to do too much with an interface that is essentially a simple ad hoc networking and cable-replacement technology. This led to diffuse and ill-defined application profiles and nightmarish interoperability woes.

"Bluetooth's original mistake was to try to be the solution for all things, and that was clearly not a correct strategy," said Mike Foley, executive and technical director of the Bluetooth SIG. "Now we've had time to think it through and clearly define what the technology is good for, and this helps things."

Yet many in the industry wonder if it may be too late, and if Bluetooth may get squeezed by Wi-Fi and the emerging flavors of ultrawideband (UWB) communications on the high end and a clutch of contenders on the low. These include Zigbee, RFID and near-field communications.

NFC is being pushed hard by Philips, Sony and now Nokia. The Zigbee specification is on the cusp of being formally announced, and companies such as Ember, Freescale and Chipcon already have Zigbee-compliant chips ready for market.

The Bluetooth waters were further roiled in August, with the announcement by Ericsson — the instigator and driver of the specification — that it would pull the plug on its Bluetooth licensing operation. The decision was a simple expenditure-vs.-return calculation in a market with rapidly falling chip pricing. Nevertheless, it sent shivers down the spine of the Bluetooth community and ultimately sparked the decision to craft a clearly defined road map for the technology.

"The Bluetooth SIG feels it's now appropriate to do so given the confusion that's out there in the industry," Foley said.

In Foley's view, the road map starts with recognition of where Bluetooth stands in the scheme of things. With respect to Wi-Fi, UWB, Zigbee and other air interfaces and protocols, he's realistic. "Each tech has its strength. UWB isn't really a Bluetooth scenario [in terms of applications], as the bandwidth just isn't there," he said, referring to high-speed video transmissions.

Instead, the SIG plans to leverage Bluetooth's strengths as a low-power, low-cost, robust ad hoc personal connectivity scheme — and build from there. Those inherent strengths have gained Bluetooth a solid footing as a headset technology for PCs, PDAs and cell phones, with automotive hands-free applications also gaining traction. According to ABI Research (Oyster Bay, N.Y.), more than 22 million vehicles will have factory-installed Bluetooth by 2008, representing 16 percent of the global automobile market. InStat/MDR expects total Bluetooth IC shipments to reach 721 million by 2008, with revenue totaling $1.7 billion.

Throughput advances
Now, according to Foley, the goal is to expand Bluetooth into wireless automation, peer-to-peer gaming, audio/video applications and file sharing. The most obvious improvement comes in the form of throughput. The Enhanced Data Rate specification that will bring Bluetooth from 1 to 3 Mbits/second was finalized in April, but already companies such as CSR (Cambridge, England) have introduced products built on versions of it. Those chips, however, were not formally Bluetooth-qualified.

Since April, "there has been testing to verify the specification to show that multiple manufacturers can interoperate," said Foley. "Only now are we announcing the spec and that it is part of the Bluetooth qualification program — and [that members] can start shipping those products."

Other enhancements outlined in the road map involve quality-of-service, security, power consumption and range. QoS was driven by the PC industry's need to enable multiple devices to work well when connected simultaneously to a computer, said Foley. "Devices will be able to specify data requirements — both bit rate and latencies — and then enable the PC to schedule the data appropriately." Though the feature is driven by the PC market, Foley emphasized that "as more and more devices come out we also see it being important for smart phones and PDAs."

Security and power
The question of security and privacy as users initiate the pairing process has driven the Bluetooth SIG to enhance the authentication scheme. "Currently, it is possible for someone to 'sniff' the signal when two devices are pairing and then go offline and try and uncover the PIN used while pairing," said Foley. The PIN is only four digits, which amounts to 10,000 possible combinations, so it can be cracked in a matter of hours, he said. The SIG plans to switch to longer-sequence alphanumeric PINs, "to drive the number of combinations into the millions to make [cracking the PIN] impractical."

Foley added that the SIG will make security enhancements in every release of the core specification going forward as both security and implementation needs are identified.

Lower power is critical for Bluetooth since almost all its applications are battery-powered. "We've learned quite a bit on how power is generated during data transmissions, etc., and we're going to take that knowledge and take optimizations and update the specification in 2005," Foley said. He predicted that such optimizations will not only enhance the current class of Bluetooth devices, but also enable Bluetooth to tackle a whole new class of applications.

Along with a multicast mode, optimizations will focus on transmit-and-receive power consumption, "as the standby power is now basically leakage [current]," Foley said. The main efficiencies derive from streamlining the protocol. "It currently takes approximately eight round trips to exchange data. We will reduce that to an ask-and-reply." Foley believes this will provide years of battery life and enable the use of Bluetooth in sensors for both industry and home automation and security.

For those applications, greater range is also a requirement. "Existing radios today can cover a factory floor," said Foley, "but if you want to go beyond that we plan to expand the range by the 2006 time frame." This will be done through enhanced sensitivity on the receive side, the use of powered "collector" stations that will relay connections, and stronger coding techniques. While stronger coding for better error correction reduces overall payload for a given throughput rate, Foley pointed out that only small chunks of data need to be exchanged in sensor applications, so more error correction can be used to extend the overall range.

The SIG also plans to accelerate the qualification process for Bluetooth devices and to do a better job of formalizing profiles and Bluetooth classes, said Foley. The group will mount a Web site where developers can download the requirements for those profiles. Testing of profiles will be improved through the development of a dongle that can attach to a PC and test a headset profile, for example, he said. "We are forward-enabling the devices, opening up new classes of devices and working with membership to lower barriers to bringing Bluetooth devices to market," he added.