Understanding the Magic of Bluetooth Technology

By: Jon Arnold

Bluetooth technology is a low-power, low-cost wireless technology for short-range radio communication between various fixed and/or portable electronic devices such as mobile phones, laptops, PDAs, cars, stereo headsets, MP3s, digital cameras, PCs and computer peripherals. Bluetooth also refers to the standard communication protocol (IEEE 802.15.1) specifically designed for this kind of short-range wireless communication.

The core of Bluetooth technology lies in a low-cost 9 mm x 9 mm microchip that functions as a short-range radio link when inserted into an electronic device, making the device Bluetooth-enabled. Wireless communication between various bluetooth-enabled devices takes place via these radio links, instead of via cables as used in normal networking. Since Bluetooth technology uses radio signals, which are omni-directional and can be transmitted through walls and other obstacles, Bluetooth-enabled devices don't need to be in line of sight or be pointing at each other.

Bluetooth radio modules operate in the open, unlicensed ISM (industrialscientificmedical) spread-spectrum 2.4 GHz frequency band, divided into 79 channels separated by 1 MHz each. To avoid interference from other signals, the Bluetooth signal hops to a new channel every time it transmits or receives a data packet, making Bluetooth connection robust and secure. The communication range of Bluetooth technology varies from 1 m to 100 m, depending upon the maximum power permitted (1 mW to 100 mW). Because of this channel hopping, there should not be a consistent problem with other devices using the 2.4 Ghz frequency band, such as old cordless phones.

Each Bluetooth-enabled device can simultaneously communicate with up to seven other devices within a single personal area network, called a piconet. Each device can simultaneously belong to several piconets. Each device negotiates with each other via a defined device name so that each device can keep track of who it is communicating with. The device name to use when you are setting up your Bluetooth device is typically cleared stated in the accompanying device documentation.

Bluetooth technology offers built-in security with 128-bit encryption and PIN code authentication. When Bluetooth products identify themselves, they use the PIN code the first time they connect, thereafter staying securely connected.

Practical Applications of Bluetooth Networking

Some of the popular applications of Bluetooth technology are in wireless networking between a mobile phone and a laptop/desktop, between a mobile phone and a hands-free headset, between PCs in a restricted space and between the input and output devices of a PC (e.g., mouse, keyboard, printer). Bluetooth technology can also be used to transfer files, images and MP3 files between mobile phones or between MP3 players/digital cameras and computers.

Limitations of Bluetooth Technology

Short communication range (up to 100 m) is the greatest limitation of Bluetooth technology. Also, the data transfer rates are much lower compared to other wireless communication technologies. Susceptibility to interference from other devices operating in the 2.4 MHz band, notwithstanding adaptive frequency hopping, is another limitation. The Bluetooth technology is still not fully developed, so there is plenty of room for improvement.

Bluetooth-Enabled Devices

The Bluetooth wireless technology specification is available free-of-charge to Bluetooth member companies around the world. Many companies are interested in making their devices Bluetooth-enabled in order to avoid the clutter of wires with seamless connections and offer simultaneous transmission of data and voice as in hands-free talking.

Bluetooth technology is commercially available in a wide range of applications such as mobile phones, automobiles, medical devices, play stations and many more.

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