Tec Guide

Bluetooth -

A short-range radio technology aimed at simplifying communications among Internet devices and between devices and the Internet. It also aims to simplify data synchronization between Internet devices and other computers.

Products with Bluetooth technology must be qualified and pass interoperability testing by the Bluetooth Special Interest Group prior to release. Bluetooth's founding members include Ericsson, IBM, Intel, Nokia and Toshiba.

What is Bluetooth?

• Bluetooth is a wireless connectivity system


• Bluetooth is an industry initiative founded by Promoter
  Companies Agere, Ericsson Technology Licensing AB, IBM
  Corporation, Intel Corporation, Microsoft Corporation,
  Motorola Inc, Nokia and Toshiba Corporation.


• It provides cable replacement and personal area
  networking for static and mobile devices.


• Global Use in Unlicensed ISM Band.


• Radio designed for low cost and power consumption.

Advantages Of Bluetooth:

• Wireless technology


• Protocol based


• Short Range


• Low Power


• Located in the 2.45GHz ISM Band


• Personal Area Network (PAN) - cable
  replacement


• Open specification

How Bluetooth started:

History - Harald I Bluetooth (Danish Harald Blåtand) was the King of Denmark between 940 and 985 AD. The name "Blåtand" was probably taken from two old Danish words, 'blå' meaning dark skinned and 'tan' meaning great man. He was born in 910 as the son of King Grom The Old (King of Jutland, the main peninsula of Denmark) and his wife Thyre Danebold (daughter of King Ethelred of England). Like many Vikings, Harald considered it honorable to fight for treasure in foreign lands. When Harald's sister Gunhild was widowed after the death of the violent Norwegian king Erik Blood Axe, she came to Denmark to seek Harald's help in securing control of Norway. Harald took the opportunity to seize control himself. By 960 he was at the height of his powers, ruling over both Denmark and Norway. He was baptized by a priest named Poppo, sent by the German emperor. He then created a monument that read: "King Harald raised this monument to the memory of Grom his father and Thyre his mother. Harald conquered all of Denmark and Norway and made the Danes Christian". These words were also carved in stone called rune stones. Harald was killed in a battle in 985. Harald completed the country's unification begun by his father, converted the Danes to Christianity, and conquered Norway. The expansion begun by Harald in Norway was continued by his son Sweyn I, who conquered England in 1013. Under Sweyn's son Canute there grew up a great Anglo-Scandinavian kingdom that included parts of Sweden.

Old Harald Bluetooth united Denmark and Norway, Bluetooth of today will unite the worlds of computers and telecom (hopefully longer than the few years Harald's Viking kingdom survived). In 1994 Ericsson Mobile Communications initiated a study to investigate the feasibility of a low-power low-cost radio interface between mobile phones and their accessories. In Feb 1998, five companies Ericsson, Nokia, IBM, Toshiba and Intel formed a Special Interest Group (SIG). The group contained the necessary business sector members - two market leaders in mobile telephony, two market leaders in laptop computing and a market leader in digital signal processing technology. It is estimated that before year 2002, Bluetooth will be a built-in feature for more than 100 million mobile phones and several million communication devices ranging from handsets and portable PCs to desktop computers and notebooks.

Why Bluetooth was developed -

• Low cost implementation


• Small implementation size


• Low power consumption


• Robust, high quality data & voice transfer


• Open global standard

Practical use of Bluetooth -

• Mobile phones – PDA – Laptop synchronisation


• Wireless Headsets and Hands Free Kits


• VOIP Cordless phones and intercoms


• PC to printer, fax, scanner


• Connecting household appliances and systems


• Public Information Access Points

Wireless Link between devices -

Bluetooth Protocol Stack -

RF Overview
Frequency Bands and Channels -

• Frequency Range 2.402GHz to 2.480GHz


• 79 Channels


• 1MHz Channel Spacing


• Frequency Hopping Spread Spectrum (FHSS)


• 1600 hops/s

RF Overview
Transmitter Characteristics -

• 3 power classes (*optional power control)
  
  Class 1 = 20dBm
  
  Class 2 = 4dBm*
  
  Class 3 = 0dBm*


• Gaussian Frequency Shift Keying (GFSK)


• ±75kHz frequency tolerance.

RF Overview
Receiver Characteristics -

• Sensitivity level of -70dBm or better


• Optional Receiver Signal Strength Indicator
  (RSSI)


• Co-channel and Adjacent Channel Interference
  requirements


• Out of Band Blocking performance
  requirements


• Maximum Usable input Level -20dBm or better

Baseband Layer -

• Sits above the RF layer


• Channel coding and decoding


• Low level timing control


• Management at packet level

Link Manager Layer -

• Attaching slaves to a piconet


• Breaking connections to detach slaves


• Link configuration


• Establishes ACL (data) and SCO (voice) links


• Hold, Sniff and Park modes


• Controls Test Modes


• Power Control

HCI (Host Controller Interface)
Layer -

• Standard interface between upper and lower protocol layers


• Allows the mix and match of Protocol Stack
  and RF Chip Sets


• Used for test and measurement commands


• Commands are used to control the Bluetooth
  module and monitor its status

L2CAP (Logical Link Control and
Adaptation Protocol) Layer -

• Multiplexing between different higher layers
  with the lower layers


• Segmentation and re-assembly to allow the
  transfer of larger packets than the lower
  layers support


• Group Management - allowing one-way
  communication to a group of devices


• QOS (Quality of Service) management

RFCOMM Layer -

• Emulation of serial ports over the L2CAP layer


• Based on the ETSI standard TS 07.10


• Support for legacy applications

Service Discovery Protocol (SDP)
Layer -

• Used to discover which services are available
  and to determine the characteristics of those available services


• A specific Service Discovery protocol is needed in the
  Bluetooth environment, as the set of services that are
  
  available changes dynamically based on the RF proximity
  of devices in motion, qualitatively different from service
  
  discovery in traditional network-based environments. The
  service discovery protocol defined in the Bluetooth
  
  specification is intended to address the unique
  characteristics of the Bluetooth environment.

Refer this link for further information - http://en.wikipedia.org/wiki/Bluetooth