Bluetooth Introduction

Bluetooth is a radio standard primarily designed for low power consumption, with a short range (power class dependent: 10 centimetres, 10 metres, 100 metres or up to 400 metres [1], ) and with a low-cost transceiver microchip in each device. Bluetooth lets these devices talk to each other when they come in range, even if they are not in the same room, as long as they are within up to 100 metres (328 feet) of each other, dependent on the power class of the product. Products are available in one of three power classes:

1. A Bluetooth mouseWireless networking between desktops and laptops, or desktops in a confined space and where little bandwidth is required
2. Bluetooth peripherals such as printers, mice and keyboards
3. Bluetooth cell phones have been sold in large numbers, and are able to connect to computers, personal digital assistants (PDAs), and various handsfree devices.
4. The standard also includes support for more powerful, longer-range devices suitable for constructing wireless LANs.
5. Transfer of files (images, mp3s, etc) between mobile phones, Personal digital assistants (PDAs) and computers via OBEX

1. Certain mp3 players and digital cameras to transfer files to and from computers
2. Bluetooth headsets for mobile phones and smartphones
3. Some testing equipment is bluetooth enabled
4. Medical applications — Advanced Medical Electronics Corporation is working on several devices.
5. Certain GPS receivers transfer NMEA data via Bluetooth.
6. Bluetooth car kits — Acura, with the 2004 Acura TL, was the first motor vehicle manufacturer to install handsfree Bluetooth technology.

Since then, other manufacturers have followed suit, with many vehicles, including the 2004 Toyota Prius and the 2004 Lexus LS 430. The Bluetooth car kits allow users with Bluetooth-equipped cell phones to make use of some of the phone's features, such as making calls, while the phone itself can be left in a suitcase or in the boot/trunk, for instance. Companies like Parrot or Motorola manufacture Bluetooth hands-free car kits for well-known brand car manufacturers.
Certain data logging equipment transmits data to a computer via Bluetooth.
For remote controls where infrared was traditionally used.
Hearing aids — Starkey Laboratories have created a device to plug into some hearing aids.
Specifications and Features
The Bluetooth specification was first developed by Ericsson, and was later formalized by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1999. It was established by Sony Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many other companies as Associate or Adopter members. Bluetooth is also IEEE 802.15.1.

Versions 1.0 and 1.0B had numerous problems and the various manufacturers had great difficulties in making their products interoperable. 1.0 and 1.0B also had mandatory Bluetooth Hardware Device Address (BD_ADDR) transmission in the handshaking process, rendering anonymity impossible at a protocol level, which was a major set back for services planned to be used in Bluetooth environments, such as Consumerium.

Many errata found in the 1.0B specifications were fixed, added support for non-encrypted channels.
Received Signal Strength Indicator (RSSI)

This version is backwards compatible with 1.1 and the major enhancements include

1. Adaptive Frequency-hopping spread spectrum (AFH), which improves resistance to radio frequency interference by avoiding using crowded frequencies in the hopping sequence,
2. Higher transmission speeds in practice,
3. extended Synchronous Connections (eSCO), which improves voice quality of audio links by allowing retransmissions of corrupted packets.
4. Host Controller Interface (HCI) support for 3-wire UART
5. HCI access to timing information for Bluetooth applications.

This version is backwards compatible with 1.x. The main enhancement is the introduction of Enhanced Data Rate (EDR) of 2.1 Mbit/s. This has the following effects (Bluetooth SIG, 2004): 3 times faster transmission speed (up to 10 times in certain cases).
Lower power consumption through reduced duty cycle.
Simplification of multi-link scenarios due to more available bandwidth.
Further improved BER (Bit error rate) performance.