Bluetooth Wireless is a technology developed by Ericsson, the Swedish telecommunications equipment manufacturer. The new wireless standard was named after the Danish king Harold 'Bluetooth', who probably also ruled Norway for some time. The Bluetooth Special Interest Group formalized the technology in 1999 almost a thousand years after King Harold Bluetooth died.

Bluetooth can work in a personal area network (PAN) used for communication among different devices within a short distance. It provides a way to connect and exchange information between devices like PDAs, mobile phones, laptops, PCs, keyboards, mice, printers and digital cameras via a secure, low-cost, globally available short-range radio frequency. It works typically within a range of 10 meters.

Bluetooth communication can take place either among these devices or for uplinking to a higher-level network like the Internet. A Bluetooth PAN can have up to eight active devices in a master-slave relationship. If you don't need a full-fledged wireless network, Bluetooth could be the ideal solution for your personal wireless needs! Bluetooth wireless technology brings you wire-free life.

A Bluetooth Master device can communicate with up to 7 Slave devices, at any given instant in time, data can be transferred between the master and one slave; but the master switches rapidly from slave to slave in a round-robin fashion. The Bluetooth specification also allows connecting two or more such groups, with some devices acting as bridges by simultaneously playing the master role in one group and the slave role in another group.

Technical Know-how of Bluetooth
The protocol operates in the license-free ISM band at 2.45 GHz. Even though Bluetooth and Wi-Fi use the same frequency range, they work with different multiplexing schemes. In order to avoid interfering with other protocols which use the 2.45 GHz band, the Bluetooth protocol divides the available frequency band into 79 channels and the transmitters change channels up to 1600 times per second.

Due to use of this technique called spread-spectrum frequency hopping, it is unlikely that several devices will be on the same frequency at the same time. This allows more devices to make full use of a limited slice of the available frequency spectrum, as any interference on a particular frequency will last only for negligible span of time.

Wi-Fi provides higher throughput and covers greater distances and requires more expensive hardware and higher power consumption. Wi-Fi eliminates the need for wired connections only for LAN access, whereas every low power application on your wish list, where you don't like wires to come in your way, where you don't want to be tied up to the end of a cable – is a candidate for Bluetooth. When low power, low range, low speed is good enough; you don't need a high speed, high power WLAN. And wouldn't it be wonderful if both technologies worked together?

Simplicity of Bluetooth
The simplest example of Bluetooth technology at work is the mobile phones, which have the Bluetooth functionality for connecting to a laptop computer. Talking about technologies, someone recently said, "When I buy a car, I want to be the driver, not the mechanic." It's very true of the Bluetooth technology. It needs to be developed and deployed in such a way that Bluetooth solutions are fully transparent to the user. If it is to become an all-pervasive technology, used by everyone, the solutions need to be almost invisible. The Bluetooth technology is fortunately developing in this direction. You don't have to learn Bluetooth to use it. Bluetooth doesn't require you to do anything special to make it work. Bluetooth-enabled devices can find each other and start their wireless radio conversation on their own.

As Bluetooth reliability and security get enhanced and well proven, even industrial process control devices will talk to each other this way. The simplicity of the Bluetooth protocol and ease of implementation make it ideal for wireless communication across a diverse set of products in many industries. Engineers are now using Bluetooth to develop remote data acquisition and instrument control applications.

The popular LabVIEW application from National Instruments now provides Bluetooth Compatibility with which LabVIEW developers can build custom Bluetooth applications to communicate with Bluetooth-enabled devices.

For building such Bluetooth solutions, compatibility is available with Operating Systems like Windows XP, Pocket PC 2003 and Palm OS. Many Bluetooth devices still use a proprietary Bluetooth driver by default and one must take care to switch to the appropriate driver for the Operating System and the System Interface being used to build the solutions.

Future of Bluetooth
The Bluetooth Special Interest Group (Bluetooth SIG) was established by Sony Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many other companies as Associate or Adopter members. With many companies taking the Bluetooth initiative and extensive development work being done on Bluetooth-WLAN Coexistence, the future of Bluetooth is exciting.

Coexistence solution architecture typically provides a 2.4 GHz Radio Frequency Device combined with a WLAN Host Interface, a Coexistence Interface and a Bluetooth Host Interface to make Simultaneous 802.11 and Bluetooth functions available. At any time, all of the available bandwidth can be dedicated to either 802.11 or Bluetooth, as long as one or the other is idle.

However, when both 802.11 and Bluetooth require bandwidth, the embedded software monitors WLAN and Bluetooth traffic patterns and uses multiplexing techniques to allocate the bandwidth for simultaneous functions. In this way, RF interference between 802.11 and Bluetooth is eliminated, packet collisions are avoided and high throughput rates are maintained.

As Voice over IP (VoIP) becomes more common, Bluetooth technology may also become useful for communication between a cordless phone and a computer listening for VoIP. The cordless phone would then just require a cradle for charging. A Bluetooth headset may be the actual device you will use to do the talking.

The author is an independent consultant. He can be contacted at dongre@usa.net

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