Stan Diehl
The inexpensive wireless platform is poised to take over short-range systems.
Few standards in the history of computing have taken off like Bluetooth, a radio-frequency-based short-range wireless-connectivity technology. The Bluetooth Special Interest Group (SIG)—founded by Intel, IBM, Ericsson, Nokia, and Toshiba and serving as a resource for companies interested in Bluetooth development—has grown to more than 1,200 member companies. Four more major companies—Microsoft, 3Com, Lucent, and Motorola—have united with the original founders to form the Bluetooth Promoter Group. All these vendors are committed to advancing Bluetooth as the next ubiquitous standard for short-range wireless connectivity, and anyone interested in wireless would be foolhardy to bet against it.
Bluetooth is designed as an inexpensive wireless-networking system for all classes of portable devices. Bluetooth-enabled devices will easily and transparently form ad hoc networks, delivering quick and convenient connections to printers, Internet access points, and workgroups. It should resolve the connectivity issues that have hampered the progress of Internet-enabled cell phones and other small portable devices. Bluetooth will provide a standard wireless connection between cell phones and personal digital assistants (PDAs), between PDAs and notebook computers, between notebook computers and local area networks (LANs), and across many other devices as a replacement for cables.
Bluetooth operates in the 2.4-GHz ISM (Industrial Scientific Medicine) band. In most countries, the frequency range is 2,400 to 2,483.5 MHz, but some countries—notably France and Spain—have set limitations on the ISM band, requiring special frequency-hopping algorithms. Products working within this reduced frequency band won't work with products using the full band, forcing additional engineering challenges for companies marketing in the reduced-band countries.
Channel spacing is 1 MHz, but some countries use different lower and upper guard bands depending on regulatory limitations. Most countries, including the United States, will use a lower guard band of 2 MHz and an upper guard band of 3.5 MHz. The radio standard calls for 0-dBm output power at the antenna, spectrum spreading with 1,600 frequency hops per second among 79 frequencies, and a gross data rate of 1 Mbit/sec. A time-division duplex scheme ensures full-duplex transmission. A Bluetooth receiver must operate at a sensitivity level of -70 dBm or better.
For more information about the Bluetooth SIG and related technologies, go to www.bluetooth.com.
Stan Diehl is the technology editor of Portable Design, another PennWell publication. This contribution is part of a longer article entitled "Constructing a Bluetooth solution" that appeared as the cover story in the November 1999 issue of Portable Design.
Bluetooth, the Viking king
No, the code name for the Bluetooth technology has nothing to do with bad dental hygiene. It's named after King Harald Bluetooth, son of Gorm "the old," who lived in Denmark between 910 and 940 AD. King Bluetooth was credited with uniting Denmark and Norway, just as the Bluetooth technology seeks to unite the portable world. The good king also brought Christianity to Scandinavia. Although it's widely held that King Harald indeed had a blue tooth, the moniker is more likely the English derivative of the original Viking language. The king had dark hair and skin, unusual for the fair Viking race, and was therefore dubbed "Blåtand," which means "dark complexion."
