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Bluetooth. by Santosh Sam Koshy. Agenda. Need for Bluetooth Brief History of Bluetooth Introduction to Bluetooth Bluetooth System Specifications Commercial Bluetooth Solutions Network of Bluetooth Devices Data and Voice support Security Issues in Bluetooth
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Bluetooth by Santosh Sam Koshy
Agenda • Need for Bluetooth • Brief History of Bluetooth • Introduction to Bluetooth • Bluetooth System Specifications • Commercial Bluetooth Solutions • Network of Bluetooth Devices • Data and Voice support • Security Issues in Bluetooth • Architecture of a Bluetooth System • References
Need for Bluetooth • Due to the widespread use of computers and other electronic gadgets at home and at office, the work place is now a labyrinth of wires, and will still get worse. • This is a problem that has to be ministered as soon as possible • The Solution: • Bluetooth • Cable Replacement
History of Bluetooth • Named after a medievalDanish King • The Bluetooth Special Interest Group (SIG) was founded in February 1998 by Ericsson, Intel, IBM, Toshiba and Nokia • The Bluetooth specification version 1.0 was released in July1999 and version 1.1 in February 2001
Introduction to Personal Area Networks • A typical office is equipped with a number of devices such as a PC, laptop, printer, fax, modem and so on.. • These devices are interconnected by wires for the purpose of sharing information. They form a Personal Area Network (PAN). • The PAN is an ad-hoc network because the number of nodes in the network is not fixed at any time. • Administering to these networks will be easier in using radio links for communication. • A number of technologies have been proposed for the same such as Bluetooth, IrDA, IEEE-802.11.. Of which Bluetooth is the most attractive choice
Bluetooth System Specifications • Operating Frequency • The Bluetooth operating frequency is 2400 – 2483.5MHz • Bluetooth radio uses Frequency Hopping and hops between channels @ 1600 hops per second • Unless the receiver knows the hop sequence, it cannot receive data • Bluetooth radios communicate using a time division duplex (TDD) discipline. • More than 2 devices may share the medium, and is therefore a TDMA • Thus it may be said that Bluetooth uses FH-TDD-TDMA
Bluetooth System Specifications (contd..) • Operating Range • The normal operating range for Bluetooth is 10 meters • The range is dependent on the power of the radio transmitter – the higher the power, the higher the range • The Bluetooth specs define 3 classes wrt the operating range
Services Supported • Bluetooth supports both voice and data services • Since voice communication is done in circuit switching mode and data communication is done in packet switching mode, both types of connections are supported in Bluetooth • The link established for voice communication is a Synchronous Connection Oriented (SCO) link, and the link established for data communication is a Asynchronous Connection Less (ACL) link.
Network Topology • In a PAN, a set of devices forms a piconet (a small network) • In each piconet, there is on master, to which all other devices (slaves) tune to. • The master decides the hop-frequency sequence and the slaves synchronize with the master to establish links • Any device can become a master/slave. for example, a cellular phone can be master or slave to a desktop
Commercial Bluetooth Solutions • Bluetooth headset • Bluetooth cordless phone • Bluetooth LAN access point • Bluetooth LCD projector • Bluetooth speakers
Core and Profile Specifications • The Core Specifications describe the details of the various layers of the Bluetooth protocol architecture, from the radio interface to the link control • The Profile Specifications are concerned with the use of Bluetooth technology to support various applications. • Each profile discusses the use of technology defined in the core specifications to implement a particular usage model
Profile Specification Cable Replacement Wireless Audio Why Profiles???? • The purpose of a profile specification is to define a standard of interoperability, so that products from different vendors that claim support to a particular usage model will work together.
f vCard WAE AT Commands TCS Bin SDP OBEX WAP TCS UDP/TCP Core Protocols IP Cable Replacement PPP Adopted Control Audio RFCOMM Logical Link Control and Adaptation Protocol (L2CAP) Host Controller Interface Link Manager Protocol Baseband Bluetooth Radio Bluetooth Protocol Stack
Protocol Architecture • The core protocols form a five layer stack containing : • Radio • Specifies details of air interface, including frequency, the use of frequency hopping, modulation scheme, and transmit power • Baseband • Concerned with the connection establishment within a piconet, addressing, packet format, timing and power control • Link Manager Protocol (LMP) • Responsible for the link setup between Bluetooth devices and ongoing link management
Protocol Architecture (contd..) • Logical Link Control and Adaptation Protocol (L2CAP) • Adapts the upper layer protocols to the baseband layer. Provides both connectionless and connection-oriented services. • Service Discovery Protocol (SDP) • Device information, services, and the characteristics of the services can be queried to enable the establishment of a connection between two or more Bluetooth devices
Protocol Architecture (contd..) • RFCOMM is the cable replacement protocol included in the Bluetooth specification. RFCOMM emulates a serial port that is designed to make replacement of cable technologies • Bluetooth specifies a telephony control protocol. TCS BIN is a bit oriented protocol that defines the call control signaling for the establishment of speech and data calls between Bluetooth devices
Protocol Architecture (contd..) • The adopted protocols include • PPP • The point to point protocol in the internet is standard protocol for transporting IP datagrams over a point to point link • TCP/UDP/IP • Foundation protocols of the TCP/IP protocol suite • OBEX • Protocol developed by the Infrared Data Association (IrDA), for the exchange of objects • WAE/WAP • Bluetooth incorporates the above too
Standby Page Page Scan Inquiry Scan Inquiry Master Response Slave Response Inquiry Response Bluetooth State Transition Diagram Connection
Bluetooth States • Standby • Default state. Only clock is running • Connection • The device is connected to the piconet as master or slave • Page • Device has issued a page. Used by master to activate and connect to a slave • Page Scan • Device is listening for a page
Bluetooth States • Master Response • Master receives a page response from a slave • Slave Response • Slave responds to a page from master • Inquiry • Device has issued an inquiry • Inquiry Scan • Device is listening for an inquiry • Inquiry Response • Device that issued inquiry receives response
In a Jist • Device sends an inquiry using a special inquiry – hopping sequence • Inquiry scanning devices respond by sending a packet • The inquiring device requests a connection to the device that responded • Paging is used to initiate the connection with the selected device • The selected device which has entered the page scan state responds • It synchronizes with the master’s timing and FH sequence
References • William Stallings, Wireless Communications and Networks, Pearson Education, 2004 • Dreamtech Software Team, Cracking the Code, Hungry Minds IDG Books India (P) Ltd, November 2001