Can We Talk? New Standards Usher in Bluetooth Era—Finally

Between the oft-quoted "Bluetooth is in full retreat" statement (since retracted) from Intel's executive vice president Sean Maloney and the withdrawal of native Bluetooth support from Microsoft's Windows XP launch, the future of Bluetooth was looking grim. Despite the flood of Bluetooth PC cards on the market, there has been a drought of Bluetooth-enabled products such as mobile phones, personal digital assistants (PDAs), and portable PCs.

Part of the reason is that, until recently, many Bluetooth devices simply did not talk to each other. Although these early Bluetooth devices conformed to Bluetooth 1.0b, the specification defined functionality only. It did not mandate specific implementation standards, leaving important parts of the specification open to interpretation. With each manufacturer following its own interpretation of the specification, interoperability problems were bound to happen.

However, there is a light at the end of the tunnel in the form of Bluetooth 1.1. The 1500-page specification not only makes for good bedtime reading but also transforms the dream of Bluetooth interoperability into a reality. The Bluetooth special interest group will support Bluetooth 1.1 throughout 2002 and into the first quarter of 2003 to help promote the adoption of the specification. Critical differences between Bluetooth 1.1 and 1.0b include security authentication, harmonization of frequencies, and data formatting interoperability.

One key issue had been the need for a stronger marketing drive for the standard, says David Hytha, vice president of Silicon Wave (San Diego). "The Bluetooth special interest group has been waiting too long," he says. When Bluetooth devices only work with other devices from the same manufacturer, the user is not encouraged to buy other Bluetooth devices.

Making Them Talk

Security. A key feature of Bluetooth is its default 128-bit encryption. When two Bluetooth devices try to establish a link, the devices exchange keys authenticating their identities. However, until 1.1 came along, this advantage was more of a handicap. If the keys do not match, the two devices will not talk to each other.

Under the previous specification, the two devices could fail to initiate link negotiation. Each device executes an algorithm to generate the key, but using 1.0b, each device could generate a different key. Generating the correct key depends on which device initiates the link (the master) and how fast the responding device (the slave) replies. A timing problem occurs when the slave processes information faster than the master, leaving each device thinking that it is the master. The result is that the devices fail to generate matching keys. Bluetooth 1.1 requires that each device confirm its status as a master or slave by acknowledging the device that initiated the link.

Frequency Hopping. Designed to operate in a noisy radio-frequency (RF) environment, Bluetooth uses a frequency-hopping scheme to make the link robust. Interference from other signals is avoided by hopping to a new frequency after transmitting or receiving a packet. Frequency hopping also has other benefits, such as limiting interference from microwave ovens and providing data security.

For the frequency-hopping scheme to function, the master and slave must synchronize their hops up and down the 2.4-GHz frequency band to maintain their connection. If the devices do not arrive at the same frequency at the same time, the devices cannot communicate. Unfortunately, France, Japan, Spain, and several other countries use the 2.4-GHz frequency for noncommercial purposes, which required a different scheme to accommodate Bluetooth devices.

Under the original specification, the 2.4-GHz frequency was divided into 79 hops, but countries already using this spectrum for noncommercial frequencies had their spectrum divided into 23 hops to avoid encroachment. The Bluetooth special interest group recently negotiated with these 23-hop countries to permit the use of 79-hop devices, allowing Bluetooth 1.1 to eliminate 23-hop devices. In effect, this removes the incompatibility barrier between 79-hop devices and 23-hop devices.

Data Formatting. Incompatible data formatting can also prevent interoperability in Bluetooth devices. Bluetooth supports up to five slots per packet to reach its maximum data transfer rate. However, not all Bluetooth devices support five-slot packets. If the master tries to send more slots per packet than the slave can support, communications between the two devices fail.

Bluetooth 1.1 solves the data-formatting issue by allowing the slave to communicate back to the master with information about the packet sizes. Now, a slave can tell a master to send as few or as many slots per packet as necessary.

Economic and Integration Obstacles

Bluetooth also suffers from an economic catch-22. For Bluetooth to become widely used, companies that make Bluetooth chips must reduce the cost of their products to a level that is appealing to electronics manufacturers. Simultaneously, until manufacturers order Bluetooth chips in high volume, prices will remain high. Current chips cost about $8 to $15. However, many Bluetooth chip manufacturers are optimistic. Simon Finch, vice president of strategic marketing for Cambridge Silicon Radio (Cambridge, UK), predicts that chip prices "will go [lower than] $5. Not next year [2002], but the year after."

In addition to meeting the new specification and bringing down the cost of chips, Bluetooth must also overcome hardware integration hurdles. In theory, Bluetooth technology is relatively simple. It uses a short-range wireless link to connect electronic devices to each other on a worldwide nonlicensed RF band at 2400–2483 MHz. Bluetooth provides automatic detection and synchronization with other Bluetooth devices in the vicinity, creating one or several dynamic wireless local-area networks.

However, the radio technology that drives Bluetooth is not quite so simple. For the most part, Bluetooth transceivers are being developed by companies that specialize in RF design. The design issues surrounding mobile phones are particularly complex. "The embedded environment in handsets is very demanding due to their small size and all of the radio frequencies around it," says Kimmo Myllymaki, general manager of Bluetooth solutions at Nokia (Helsinki, Finland).

The two major circuits in a transceiver are the RF and baseband circuits. The RF circuit is an analog circuit, whereas the baseband controller is a digital circuit. The problem lies in integrating the sensitive analog circuit with the noisy digital circuit. Integrating everything into a single chip is done to keep costs low.

One possible solution may be obvious to some engineers. Because most devices to which a Bluetooth interface may be added already has a host processor and other digital circuits, why not integrate the baseband controller with the host controller instead of the RF circuit? This solves the problem by isolating the RF circuit from the digital circuit.

Now that Bluetooth 1.1 has been ratified, product rollout can begin in earnest. As of November 2001, 251 Bluetooth 1.1–qualified products were listed at the Bluetooth special interest group Web site (http://www.bluetooth.org). Many manufactures of Bluetooth devices predict a positive future for the wireless technology. "We definitely foresee mass adoption of Bluetooth phones, cameras, PCs, and other devices," said Peter Bodor of Sony Ericsson (London). "Already today, if you take a Sony camcorder, you can take a digital picture, send it via Bluetooth to an Ericsson phone and then send it over the cellular network as an e-mail to somebody's computer." It may be a little later than expected, but it looks like Bluetooth has finally arrived.

3GPP Marking Gets Stamp of Approval

The 3rd Generation Partnership Project (3GPP) group has agreed to permit implementers of the specifications to mark their equipment and documentation with the 3GPP name and logo. The presence of a 3GPP mark asserts a claim of compatibility with other products and services based on 3GPP specifications, assuring users, network operators, manufacturers, and service providers of device interoperability. Note that the mark does not imply actual testing; it merely functions as a manufacturer's assurance of compliance with the specifications.

3GPP was established for the preparation and maintenance of a set of technical specifications for 3rd-generation (3G) mobile systems based on global system for mobile telecommunications core networks and radio access technologies supported by 3GPP partners. The 3GPP name and logo were registered by the European Telecommunications Stand-ards Institute as a trademark on behalf of the 3GPP partners.

Although many in the telecommunications industry are familiar with 3GPP, it is largely unknown among users. The decision by the 3GPP partners to permit the use of the 3GPP name and logo was motivated by their desire to improve user awareness of the significance of 3GPP specifications as 3G networks, terminals, and services are launched.

In other announcements, 3GPP issued new plans to enhance mobile communications. These include specifications for location services (LCS) on packet-mode systems, high-speed download packet access (HSDPA), and full Internet capabilities on 3G systems.

The completion of LCS specifications for packet-mode systems allows providers to offer varied services such as sending user location information for emergency calls to locating the nearest pizzeria. LCS specifications include general packet radio service systems, or 2.5G systems, as well as circuit-mode and packet-mode 3G systems.

Using packet technology, HSDPA opens the door to high-speed data delivery for 3G terminals. High data rates promise to provide multimedia capabilities that were previously unavailable because of limitations in the radio access network.

The IP multimedia system (IMS) brings full Internet functionality to 3G systems. The implementation of Internet protocols (IPs) will enable 3G systems to offer users access to Internet and multimedia content. Unlike traditional telecommunications protocols, IP can offer communication over many different types of networks. This makes possible various combinations of fixed and mobile, and wired and wireless networks. Consequently, customers will be able to experience seamless telecommunications while their phone call is being passed over a variety of networks. In addition, IMS uses IP version 6, an improvement over the widely deployed version 4.

The HSDPA and IMS specifications form part of the 3GPP Release 5 specifications, scheduled for the first quarter of 2002. The basic descriptions have been completed, and the detailed work is on target for completion by the first quarter of 2002.

Stricter Requirements in Revised Standard for Medical EMC

The international medical devices EMC standard, IEC 60601-1-2, was revised on September 30, 2001. This major rewrite of the standard will affect medical devices that are currently in development or in production. The changes include more-stringent emission requirements and immunity qualifications. Manufacturers will have a projected grace period of 10 months to reevaluate product de- signs and incorporate changes necessary for compliance to the new standard.

Significant changes were made to the standard, affecting what is considered acceptable performance. Under test conditions, the equipment may exhibit degradation of performance; however, the following will not be allowed:

• Failure of components.
• Changes in programmable parameters.
• Error of a displayed numerical value sufficiently large to affect diagnosis, therapy, or treatment.
• Failure of automatic diagnosis or treatment equipment to diagnose or treat, even if accompanied by an alarm.
• Reset to factory defaults.
• Change of operating mode.
• False alarms.
• Cessation of any intended operation, even if accompanied by an alarm.
• Initiation of any unintended operation, including unintended or uncontrolled motion, even if accompanied by an alarm.
• Artifacts, distortions, or noise in an image or waveform in which the artifact, distortion, or noise is indistinguishable from physiologically produced signals or interferes with the interpretation of physiologically produced signals.

For equipment with multiple functions, the criteria apply to each function, parameter, and/or channel.

The second edition of EN 60601-1-2 outlines a comprehensive method for ensuring EMC of medical devices. The standard provides guidance for testing and labeling medical devices and maintaining an appropriate electromagnetic environment during the use of devices.

Manufacturers marketing medical devices in the European Union should be aware that the European medical devices EMC standard, EN 60601-1-2, is scheduled for revision. The revision becomes official on February 13, 2002. Although the transition period will likely be longer than that of IEC 60601-1-2, changes are expected to be significant.

ACA Extends Regulations on EMR Limits

The Australian Communications Authority (ACA) is extending the scope of the electromagnetic radiation (EMR) human exposure standard to cover virtually all radio-frequency transmitters. In addition to the human exposure limits, the standards include a mandatory test method and labeling requirements.

The standard is scheduled to take effect on January 1, 2002, and applies to mobile and portable transmitting equipment capable of operating in the frequency band of 3 kHz to 300 GHz and featuring an integrated antenna. The purpose is to regulate the performance of certain radio transmitters to protect people exposed to emitted EMR.

Devices intended to be used only at sea to alert rescue authorities to the location of the sea craft or a person in distress will not be subject to the new standard because the life-saving potential outweighs the risks of exposure to EMR.

The standard describes a specific absorption rate testing method for mobile and portable transmitting equipment with an integrated antenna where the normal position of use is close to the human head. The test is applicable to devices that are capable of operating in the frequency band of 800–2500 MHz. The specified test uses a phantom head and is similar to the FCC model.