Athipathy Bluetooth Tech

By, G.Athipathy II B.Tech IT

What is Bluetooth? “Bluetooth wireless technology is an open

specification for a low-cost, low-power, shortrange radio technology for ad-hoc wireless communication of voice and data anywhere in the world.”

One of the first modules (Ericsson)

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A recent module

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Overview of Bluetooth History What is Bluetooth?  Bluetooth is a short-range wireless communications technology. Why this name?  It was taken from the 10th century Danish King Harald Blatand who unified Denmark and Norway. When does it appear?  1994 – Ericsson study on a wireless technology to link mobile phones & accessories.  5 companies joined to form the Bluetooth Special Interest Group (SIG) in 1998.  First specification released in July 1999 (beta version). 16 April 2009

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Bluetooth Goals & Vision Originally conceived as a cable replacement

technology Short-Range Wireless Solutions Open Specification(CDMA,GSM) Voice and Data Capability Worldwide Usability Other usage models began to develop: Personal Area Network (PAN) Ad-hoc networks Data/voice access points

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Technical features Connection Type

Spread Spectrum (Frequency Hopping) & Time Division Duplex (1600 hops/sec)

Spectrum

2.4 GHz ISM Open Band (79 MHz of spectrum = 79 channels)

Modulation

Gaussian Frequency Shift Keying

Transmission Power

1 mw – 100 mw

Data Rate

1 Mbps

Range

30 ft

Supported Stations

8 devices

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Bluetooth FHSS Employs frequency

hopping spread spectrum Reduce interference

with other devices Pseudorandom

hopping 1600 hops/sec- time

slot is defined as 625 microseconds 16 April 2009

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Time-Division Duplex Scheme  Channel is divided into consecutive slots (each 625 µs)  One packet can be transmitted per slot  Subsequent slots are alternatively used for transmitting and

receiving  Strict alternation of slots between the master and the

slaves  Master can send packets to a slave only in EVEN slots  Slave can send packets to the master only in the ODD

slots

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Typical Bluetooth Scenario Bluetooth will support wireless point-to-

point and point-to-multipoint (broadcast) between devices in a piconet. Point to Point Link Master - slave relationship Bluetooth devices can function as

m

s

masters or slaves

Piconet It is the network formed by a Master and one or more slaves (max 7) Each piconet is defined by a different hopping channel to which users synchronize to s Each piconet has max capacity (1 16 April 2009 Mbps)

m

s

s 9

Master Active Slave Parked Slave Standby

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All devices in piconet hop together.

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File Transfer Profile

• Profile provides: • Enhanced client-server interactions: - browse, create, transfer folders - browse, pull, push, delete files 16 April 2009

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Headset Profile

• Profile provides: • Both devices must provide capability to initiate connection & accept/terminate calls. • Volume can be controlled from either device. • Audio gateway can notify headset of an incoming call. 16 April 2009

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Core Bluetooth Products • Notebook PCs &

Desktop computers • Printers • PDAs • Other handheld devices • Cell phones • Wireless peripherals:

• CD Player • TV/VCR/DVD • Telephone Answering Devices • Cordless Phones • Cars

• Headsets • Cameras

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Security Security Measures  Link Level Encryption & Authentication.  Personal Identification Numbers (PIN) for

device access.  Long encryption keys are used (128 bit keys).  These keys are not transmitted over wireless.  Further encryption can be done at the

application layer.

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Bluetooth vs. IrD Bluetooth

•IrD



Point to Multipoint

—Point to point



Data & Voice communication

—Intended for Data Communication

Devices can be mobile

—Range 1 m





—Cannot penetrate solid objects

Range 10 m

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Summary A new global standard for data and voice Eliminate Cables Low Power, Low range, Low Cost network devices Future Improvements  Master-Slave relationship can be adjusted

dynamically for optimal resource allocation and utilization.  Adaptive, closed loop transmit power control can

be implemented to further reduce unnecessary power usage. 16 April 2009

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Key Features Low complexity Low Cost Low Powered: Battery Powered  Fast Acknowledgement  Shorter Packets

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References  http://www.bluetooth.com  http://www.google.com  http://www.brainboxes.com  http://www.palowireless.com

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