BLUETOOTH WIRELESS TECHNOLOGY Maureen Stella B. Lim

What is Bluetooth? A way to form connections between electronic devices in close proximity Cable-replacement technology It is a radio-frequency technology that uses the 2.4 GHz Industrial-Scientific-Medical (ISM) band To be Bluetooth certified, a device must pass interoperability testing by the Bluetooth Special Interest Group (SIG), thus assuring that products meeting the specification will be able to interact with all other Bluetooth-certified products.

Bluetooth ideal for small devices, short range, and low power radio links fit for connecting PCs and laptop computers, phones, printers, and cameras. Low power Bluetooth devices have a range of about 30 feet.

Bluetooth Features Wireless and automatic Inexpensive The ISM band that Bluetooth uses is regulated, but unlicensed. Handles both voice and data Signals are omni-directional Uses frequency hopping

Network Topology M S M S S Piconet Scatternet

Packets All data on the piconet channel are conveyed in packets Each packet consists of three entities Acces Code = used for timing synchronization, offset compensation, paging and inquiry Header = information for packet acknowledgment, numbering, flow control, slave address, error check Payload = voice field or data field

Radio Frequency and Spectrum Hopping Uses fast acknowledgment and frequency-hopping Bluetooth divides the 2.4 GHz frequency band into 79 channels (from 2.402 to 2.480 GHz) Jumps to a new frequency after every packet

Physical Channel Piconets are formed by two or more Bluetooth devices using the same channel The channel is represented by a pseudo-random hopping sequence Hopping sequence - unique for each piconet and determined by the Bluetooth device address of the master Phase - determined by the Bluetooth clock of the master M S Piconet Master Slave

Physical Channel The channel is divided into time slots, each 625 microseconds long Time-division multiplexing (TDM) scheme = a master device always uses an even-numbered slot when it transmits, and a slave uses an odd-numbered slot.

Physical Links 1. Synchronous Connection Oriented (SCO) Symmetric point-to-point link Carries voice information Reserved time slots to guarantee timely transmission Works at 64 Kb/s

Physical Links 2. Asynchronous Connection Less (ACL) Primarily for data Established on a per-slot basis Support point-to-multipoint transmissions A slave can only transmit only after receiving a packet from a master For this purpose, the master can send a polling packet Can transmit as much as 721 Kb/s in one direction

Physical Links

Connection Set-up Step 1: Inquiry procedure Source: inquiry state = sends out inquiry packets Destination: inquiry scan state Destination: inquiry response state = sends an inquiry reply to the source

Connection Set-up Step 2: Paging Procedure Source pages another device Destination receives page Destination replies Source sends an FHS packet to the destination Destination sends second reply Destination and source then switch to the source channel parameters

Error Checking 1/3 Forward Error Checking (FEC) 2/3 FEC Implemented by repeating three bits at a time 2/3 FEC Generator polynomial is used to encode 10 bit code to 15 bit code Automatic Repeat Request requires that the header error and cyclic redundancy checks are okay

Whose teeth are blue? 10th century Scandinavian king, Harald Bluetooth managed to unite several unruly kingdoms. Thus, Bluetooth is a reference to the taming of a myriad of unruly competing standards by defining one world-wide specification.