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Wireless Personal Area Networks (WPAN). Objectives: To introduce Ad Hoc networking and discuss its application domain. To provide a detailed study of the Bluetooth Wireless Technology including its architecture and protocol..

Outline. Motivation History Application and usage scenarios Network architecture Piconets Scatternets Protocol stack Core protocols Cable replacement and telephony control protocols Profiles Packet structure Future developments Wi-Fi vs. Bluetooth.

Bluetooth - Motivation. A technology that aims at ad-hoc piconets -- LAN with very limited coverage without the need for infrastructure To connect small devices in close proximity (about 10 m) The envisaged gross data rate is 1 Mbits/s Both asynchronous (data) and synchronous (voice) services Transceiver should be very cheap Low power consumption chip Replace IrDA and solve its main problems: limited range – 2m for built-in interfaces line of sight usually limited to two users, only point-to-point connections are supported no internet working functions has no MAC Big advantage: COST.

Bluetooth. History 1994: Ericsson (Mattison/Haartsen) initiated “MC-link” (multi communicator link) project Renaming of the project: Bluetooth according to Harald “Blåtand” Gormsen [son of Gorm], King of Denmark in the 10 th century 1998: foundation of Bluetooth SIG, www.bluetooth.org 1999: erection of a rune stone at Ercisson/Lund ;-) 2001: first consumer products for mass market, spec. version 1.1 released 2005: 5 million chips/week Special Interest Group Original founding members: Ericsson, Intel, IBM, Nokia, Toshiba Added promoters: 3Com, Agere (was: Lucent), Microsoft, Motorola > 10000 members Common specification and certification of products Same time, an IEEE study group for a WPAN specifications started IEEE802.15 – Requirements fulfilled by Bluetooth.

History and hi-tech…. Rainos runsten till Ericsson.jpg (48032 bytes).

…and the real rune stone. bluetooth_harald_original.

Bluetooth Was Originally a Cable-Replacement Technology.

You arrive at the office …. In the Office …. While in a meeting, ….

On the road …. You arrive at the airport …. You enter the airport waiting lounge, ….

Bluetooth - overview. Consortium: Ericsson, Intel, IBM, Nokia, Toshiba… Scenarios: connection of peripheral devices loudspeaker, joystick, headset support of ad-hoc networking small devices, low-cost bridging of networks e.g., GSM via mobile phone - Bluetooth - laptop Simple, cheap, replacement of IrDA, low range, lower data rates, low-power Worldwide operation: 2.4 GHz Available globally for unlicensed users Resistance to jamming and selective frequency fading: FHSS over 79 channels (of 1MHz each), 1600hops/s Coexistence of multiple piconets: like CDMA Links: synchronous connections and asynchronous connectionless Interoperability: protocol stack supporting TCP/IP, OBEX, SDP Range: 10 meters, can be extended to 100 meters Documentation: over 1000 pages specification: www.bluetooth.com.

Bluetooth. Universal radio interface for ad-hoc wireless connectivity Interconnecting computer and peripherals, handheld devices, PDAs, cell phones – replacement of IrDA Embedded in other devices, goal: 5€/device (already < 1€) Short range (10 m), low power consumption, license-free 2.45 GHz ISM Voice and data transmission, approx. 1 Mbit/s gross data rate Supports open-ended list of applications Data, audio, graphics, videos.

Characteristics. 2.4 GHz ISM band, 79 (23) RF channels, 1 MHz carrier spacing Channel 0: 2402 MHz … channel 78: 2480 MHz G-FSK modulation, 1-100 mW transmit power FHSS and TDD Frequency hopping with 1600 hops/s Hopping sequence in a pseudo random fashion, determined by a master Time division duplex for send/receive separation Voice link – SCO (Synchronous Connection Oriented) FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, circuit switched Data link – ACL (Asynchronous ConnectionLess) Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 kbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switched Topology Overlapping piconets (stars) forming a scatternet.

Bluetooth Application Areas. Data and voice access points Real-time voice and data transmissions Cable replacement Eliminates need for numerous cable attachments for connection Ad hoc networking Device with Bluetooth radio can establish connection with another when in range Developed in late 90s V1.2 → 1Mbps V2.0 → 3Mbps V3.0 → 24Mbps.

Bluetooth Architecture. Piconets and Scatternets Piconet is the basic unit of networking One master device and seven slaves Slave can only communicate with its Master Slave can be master of another piconet This is called a scatternet.

Piconets and Scatternets. Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel and phase Scatternet Device in one piconet may exist as master or slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth.

Piconet. Collection of Bluetooth devices connected in an ad hoc fashion and synchronizes to a master node One unit acts as master and the others as slaves for the lifetime of the piconet All devices have the same network capabilities The node establishing the piconet automatically becomes the master Master determines hopping pattern, slaves have to synchronize Each piconet has a unique hopping pattern Participation in a piconet = synchronization to hopping sequence Each piconet has one master and up to 7 simultaneous slaves (> 200 could be parked) Parked device is an inactive device (can be reactivated in milliseconds) Standby device do not participate in piconet If a parked device wants to communicate and there are 7 active slaves, then one of the slaves has to switch to park mode.

Forming a piconet. All devices in a piconet hop together Master gives slaves its clock and device ID Hopping pattern: determined by device ID (48 bit, unique worldwide) Phase in hopping pattern determined by clock Addressing Active Member Address (AMA, 3 bit, 8 nodes) for all active nodes Parked Member Address (PMA, 8 bit, 256) for parked nodes SB devices do not need address.

Scatternet. Linking of multiple co-located piconets through the sharing of common master or slave devices Devices can be slave in one piconet and master of another Master-slave can switch roles Communication between piconets Devices jumping back and forth between the piconets Overlapping piconets experience collisions.

Piconet4 Piconet2 Piconet 1 . Piconet3 • Shared Slave Master/Slave switch.

Piconets & Scatternets. M. S. S. S. S. S. S. S. M/S.

Bluetooth Standards. Details of various layers of Bluetooth protocol architecture Bluetooth v1.1 ratified in 2002 as IEEE 802.15.1 Bluetooth v2.0 goes to up to 3Mbps – 2004 Bluetooth v2.1 adopted July 2007 Wibree, an ultra low power Bluetooth technology adopted as part of the Bluetooth specification – 2007. Bluetooth v3.0 adopted April 2009. up to 24Mbps.

Bluetooth protocol stack. Radio. Baseband. Link Manager.

Protocol stack (core protocols). Two different kinds of physical links: Synchronous Connection oriented (SCO) – for audio Asynchronous ConnectionLess (ACL) – transmission of data Audio : interfaces directly with the baseband. Each voice connection is over a 64Kbps SCO link..

Protocol Stack. Telephony Control Specification (TCS) defines the call control signaling for the establishment of speech and data calls between Bluetooth devices RFCOMM (cable replacement ) provides emulation of serial links.

Bluetooth Profiles. L2CAP. RFCOMM. OBEX. SDP. L2CAP.

Establishing a connection: BT – States. Standby: unconnected but awake Inquiry: listening or wanting to connect Page: setting up connections Active: Connected or Transmitting.

Bluetooth – Establishing a connection. .

Wi-Fi v Bluetooth. Wi-Fi LAN (local area) Medium range 54Mbps (a/g) Infrastructure LAN extension Simple connection Secure authentication via WPA2 (considered safe) Layer 1+2 only.

WPAN: IEEE 802.15.1 – Bluetooth. Data rate Synchronous, connection-oriented: 64 kbit/s Asynchronous, connectionless 433.9 kbit/s symmetric 723.2 / 57.6 kbit/s asymmetric Transmission range POS (Personal Operating Space) up to 10 m with special transceivers up to 100 m Frequency Free 2.4 GHz ISM-band Security Challenge/response (SAFER+), hopping sequence Availability Integrated into many products, several vendors.