Bluetooth technology specifies a short-range, two-way radio link that enables communication between PCs, mobile phones, PDAs, and other computer, electronic, and home theater equipment. With Bluetooth, you can easily sync contacts or calendar data between a PDA and a laptop, talk on a phone hands-free, or print wirelessly. It is a cable replacement technology like infrared, but it offers many advantages over infrared.

The Bluetooth specification focuses on keeping costs low, power consumption minimal, and size small. Its low power consumption means it can be used in battery powered devices. Bluetooth offers faster data speeds and longer transmission distances compared to infrared, and there are no line-of-site restrictions. It operates on the 2.4 GHz radio frequency, which guarantees its operability throughout the world.

History

Bluetooth is named after a 10th-century Danish king, Harald Blatand (Harld Bluetooth), known for uniting warring groups in present-day Norway, Sweden, and Denmark. It was originally developed by Ericsson, but is now managed by the Bluetooth Special Interest Group (SIG).

Bluetooth SIG is an industry group with members from the telecommunications, computer, and chip manufacturing industries. To date, more than 2,000 companies are members. The Bluetooth SIG oversees a qualification program to ensure compliance with the standard and interoperability with other Bluetooth devices. Any device bearing the Bluetooth logo has successfully completed interoperability testing.

Technical details

Speed: Bluetooth supported raw data rate is 1 Mbps. Actual data rates are 432 kbps for full-duplex transmission and 721 kbps for asymmetric transmission.

Frequency: Bluetooth uses the license-free ISM (Industrial, Scientific, and Medical) band at 2.4 GHz. In most countries, this band is available. In a few countries it is reserved for military use, but even these countries are moving to make the band available for general use. Because Bluetooth shares the same frequency range as 802.11b WLAN products, these two technologies cannot operate in the same space under some conditions.

Security: Bluetooth is designed to be as secure as wired using 128-bit authentication and encryption. Apps can also create their own security in addition to the Bluetooth connection.

Transmission Distance: Typical Bluetooth range is up to 10m. The range depends on the radio power class used. A class 2 radio has a typical range of 10m. More powerful classes support longer ranges and have higher power outputs. Most devices use a class 2 radio, and mobile devices such as cell phones, where low power consumption is crucial, can only use a class 2 radio.

Architecture: With Bluetooth, up to 8 devices can be connected simultaneously. A piconet is the term for a collection of Bluetooth devices connected in an ad hoc manner. All devices are peer units, but one device acts as the master and the other slaves for the duration of the piconet connection. Each piconet can support up to 3 full-duplex voice devices. Within a 10m area, there can be up to 10 piconets.

Applications

Bluetooth is becoming the preferred wireless technology in WPAN (Wireless Personal Area Network). Personal apps include:

– Users can connect PC to transfer files.

– Workers can collaborate on the same document using Microsoft NetMeeting.

– Users can connect to a printer without cables.

– Users can synchronize data between a handheld PDA and a laptop.

– Users can listen to music through a wireless earphone.

– Users can talk on their mobile phone with a wireless headset.

– Users can connect their laptops to the Internet using the GPRS or UMTS network of their mobile phone.