FSATIE TELECOMMUNICATION WORKSHOP

FSATIE TELECOMMUNICATION WORKSHOP Bluetooth technology survey Presented by David Johnson Mobile platform technology leader Icomtek CSIR

Contents of Bluetooth lecture • Origins and history of Bluetooth • What Bluetooth can do • Building blocks of Bluetooth – the bluetooth stack • Bluetooth ad-hoc networking • Bluetooth Security • Bluetooth profiles • Bluetooth products on the market • Bluetooth in South Africa • Competing technology • The future of Bluetooth

Origins of Bluetooth • In 1994 Ericsson 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) In July 1999 the first bluetooth specification 1.0 was released The bluetooth consortium today is comprised of 9 promoter companies who are leaders in telecomms, computing and networking and more than 2000 adopter companies Bluetooth is the fastest growing technology since the internet or the cellular phone, incredible considering that its first public outing was in mid 1998.

Origins of Bluetooth

History of Bluetooth • Harald I Bluetooth (Danish Harald Blåtand) was the King of Denmark between 940 and 985 AD who united Denmark and Norway As Harald Bluetooth united Denmark and Norway, Bluetooth of today will unite the many worlds of personal devices around us Rune stone in Danish town, Jelling depicting Harold Bluetooth

What Bluetooth can do - definition Bluetooth is a low-power, low-cost short range radio system intended to replace cables between fixed and portable devices. It is intended to replace many propriety cables with one universal radio link.

Landline Cable Replacement Data/Voice Access Points Personal Ad-hoc Connectivity What Bluetooth can do - domains

What Bluetooth can do – user level • Hot spot scenario: Let your laptop or PDA connect wireless to Internet or office while at the airport, hotel etc • Automatically sync mail, calendar, notes etc. between your PDA and PC, as soon as you get into your office • Physical access control • Let your PC, Stereo and TV all connect without cables to your loudspeakers. Let the PC, phone or PDA control them all • Take a picture with a digital camera, and send it via BT to a mobile phone, which forwards the picture to an email recipient via WAP • Pay the cab driver via the phone. • Withdrawal of money at ATMs • Setup ad-hoc wireless network at a conference

What Bluetooth can do – technical level • Data links: Can establish up to 7 simultaneous data connections between a master and it’s slaves (piconet) • Voice links: Can establish up to 3 simultaneous voice connections between a master it’s slaves (piconet) • Maximum asymmetrical data rate of 723 kbps (57.6 kbps return channel) • Maximum Symmetrical data rate of 432.6 kbps • Can have up to ten multiple self contained networks (piconets) sharing spectrum in the same area (scatternet) • Range can be up to 10m for 10mw bluetooth devices and up to 100m for 100mw bluetooth devices • Very low power consumption • Ability to discover available services on another device

Building blocks of Bluetooth – the Bluetooth stack • The Bluetooth Stack Overview • Bluetooth Stack – Radio • Bluetooth Stack – Baseband • Bluetooth Stack – Link controller • Bluetooth Stack – Link Manager • Bluetooth Stack – HCI • Bluetooth Stack – L2CAP • Bluetooth Stack – RFCOMM • Bluetooth Stack – SDP

The Bluetooth Stack Overview

Bluetooth Stack - Overview Headset Bluetooth Stack

Bluetooth Stack - Overview Access Point Bluetooth Stack

Bluetooth Stack - Radio • Bluetooth radio is a short range radio link capable of data and voice • Three classes of operating range are defined ( Class3: 1mw ~ 10cm, Class2: 10mw ~ 10m, Class1: 100mw ~ 100m ) • Uses a radio link at 2.4Ghz (2400-2483.5MHz ) which is the unlicensed ISM band also used by WLAN • GFSK (Guassian Frequency Shift Keying) modulation scheme • Uses frequency hopping spread spectrum technology (1600 hops/s) • The signal hops among 79 frequencies which have a bandwidth of 1MHz which improves interference immunity • Channel has a symbol rate of 1 Mb/s

Bluetooth Stack - Baseband • Baseband is responsible for channel coding and decoding and low level timing control and management of the link within the domain of a single data packet transfer • Each registered device has a unique 48-bit device address • Bluetooth uses TDM where the duration of a slot is 625µs • A Master and Slave transmit on alternate time slots with the master always initiating data exchange • Larger packets can use multiple slots • The Master and slave devices need to synchronize their clocks to enable reliable communication to take place

Bluetooth Stack - Baseband • Timing diagrams for data packets

Bluetooth Stack - Baseband • Bluetooth is able to form point-to-point links and point-to-multipoint links • The network of bluetooth devices is defined as a Personal Area network (PAN) • A Piconet is an arbitrary collection of Bluetooth enabled devices which are physically close enough to communicate • A Scatternet is formed when there are two overlapping Piconets, where one of the Slaves of one Piconet also forms the Master/Slave of another Piconet • A supervision timeout ensures that links are closed down when Bluetooth devices move out of range of the Piconet.

Bluetooth Stack - Baseband • Piconets (a & b) and Scatternets ( c )

Bluetooth Stack - Baseband

Bluetooth Stack - Baseband • Two types of links are defined • Data Links - ACL (Asynchronous Connection-Less) • Voice Links – SCO (Synchronous Connection Orientated) • An ACL link is a packet switched data link which is established between a Master and Slave as soon as a connection has been established. • ACL Data is carried in DH (Data High rate) packets with no FEC (Forward Error Correction) or DM (Data Medium rate) packets with FEC • A SCO link provides a circuit switched link between a Master and Slave with reserved channel bandwidth. • SCO Data is carried in HV (High Quality Voice) packets a number of selectable error correction packets

Bluetooth Stack - Baseband • Packet Types

Bluetooth Stack – Link Controller • The Link Control Layer is a state machine which drives the baseband through various stages to establish links. • It is responsible for managing device discoverability, establishing connections and once connected, maintaining the on-air links • It can drive a device through the following stages • Host Inquiry • Inquiry Scan • FHS (Frequency Hop Synchronization) packet response • Paging • Page Scan • Connection

Bluetooth Stack - Link Controller • State Diagram for Link Controller

Bluetooth Stack - Link Controller Inquiry procedure (typical time ~ 2s)

Bluetooth Stack - Link Controller Inquiry procedure (continued)

Bluetooth stack – Link Controller Bluetooth Inquiry procedure at packet level

Bluetooth Stack - Link Controller • Paging Procedure (typical time ~0.6s)

Bluetooth Stack - Link Controller The frequency hop sequence used in the connected state is calculated from the Master BD Address and Clock A connection is established once the Slave has received the Masters native clock and bluetooth address and a poll packet has been sent to confirm the connection is working

Bluetooth stack – Link Controller Bluetooth Paging procedure at packet level

Bluetooth Stack - Link Controller • Low Power connected states (Can re-establish connection in 2ms) • Connection – Hold: Device ceases to support ACL traffic for a defined period of time to free up bandwidth for other operations such as paging or inquiring, maintains AM address, after hold time expires the device resynchronizes to the CAC and listens for traffic again • Connection – Sniff: Device is given a predefined slot time and periodicity to listen for traffic, on reception of a packet during this time it will continue to listen until packets with its AM address stop and the timeout period ceases, it then waits until the next sniff period • Connection – Park: Slave gives up its AM address and only listens for traffic at predefined beacon intervals – between this it can enter a low power state. At these intervals even if there is no traffic it will synchronize its clock to the CAC.

Bluetooth Stack – Link Manager • Commands the Link Controller/Baseband • Attaches/Detaches slaves to a piconet and allocates their Active Member addresses • Configures the link which inlcudes a master-slave switch • Establishes ACL (data) and SCO (voice) links • Puts connections in low-power modes: Hold, Sniff, Park • Controls Power levels • Communicates with Link Managers on other Bluetooth devices using the Link Management Protocol (LMP) • These LMP commands are used to exchange information necessary for security negotiation • Requesting a SCO connection or Master/Slave switch is also done through LMP commands

Bluetooth Stack – Link Manager

Building blocks of Bluetooth – the Bluetooth stack • The Bluetooth Stack Overview • Bluetooth Stack – Radio • Bluetooth Stack – Baseband • Bluetooth Stack – Link controller • Bluetooth Stack – Link Manager • Bluetooth Stack – HCI • Bluetooth Stack – L2CAP • Bluetooth Stack – RFCOMM • Bluetooth Stack – SDP • Bluetooth Stack – Other Higher Layers

Bluetooth Stack - HCI • The Host Controller Interface is necessary when there is system partitioning between the baseband and Link Manager on one processor and the higher layers such as L2CAP, SDP and RFCOMM running on a serperate host processor • This can reduce the processing power needed by the bluetooth device and hence reduce cost • Creates a standard interface that can be used by different manufactures of Bluetooth devices • Three types of HCI packets are used • Command packets used by host to control the module • Event packets used by the module to inform the host • Data packets used to pass voice and data between host and module • A transport layer (USB, RS-232) is also required to carry HCI packets

Bluetooth Stack - HCI • Position of the HCI in the Bluetooth Stack

Bluetooth Stack – Logical Link Control and Adaptation Protocol (L2CAP) • Takes data from higher layers of the stack and from applications and sends it over the lower layers of the stack • Achieved by multiplexing using dedicated channel numbers and associated (Protocol Service Multiplexers) PSM’s • Segmentation and reassembly to transfer packets larger than the lower layers support • Quality of service management for high layer protocols

Bluetooth Stack – Logical Link Control and Adaptation Protocol (L2CAP) • Example setting up an L2CAP connection over HCI

Bluetooth Stack – Logical Link Control and Adaptation Protocol (L2CAP) • Segmentation and transport of L2CAP packets

Bluetooth Stack - RFCOMM • RFCOMM is a simple reliable transport protocol which can emulate the serial cable link settings and status of an RS-232 serial port • It can handle multiple concurrent connections by relying on the multiplexing features of L2CAP • It provides the following provisions • Modem status – RTS/CTS, DSR/DTR, DCD and RI • Remote line status – Break, Overrun, Parity • Remote port settings – Baud rate, parity, data bits etc. • Parameter negotiation (frame size) • Optional credit based flow control

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