Introduction to bluetooth outline Why bluetooth n History

Introduction to bluetooth

outline Why bluetooth n History n Bluetooth stack and technology n Reference n

bluetooth n Why bluetooth? ¨ Cable replacement between devices ¨ Open Specification ¨ Low power consumption ¨ Connection can be initiated without user interaction ¨ Devices can be connected to multiple devices at the same time

history n The technology was born in 1994 n Standardized by the Bluetooth Special Interest Group (SIG), a consortium founded in spring 1998 by Ericsson, Intel, IBM, Nokia, and Toshiba n The first version was released July 1999

stack

stack n Bluetooth stack and OSI layers

stack n Bluetooth Stack ¨ Transport n Protocol group Radio , Baseband , L 2 CAP and HCI ¨ Middleware Protocol group PPP , IP , TCP , WAP , OBEX, Ir. DA n RFCOMM, TCS, SDP n ¨ Application group

stack

stack

stack n Transport Protocol group ¨ Allow Bluetooth devices to locate each other ¨ manage physical and logical links with higher layer protocols and applications ¨ support both asynchronous and synchronous transmission

stack n Middleware Protocol group ¨ includes third-party and industry-standard protocols as well as Bluetooth SIG developed protocols ¨ These protocols allow existing and new applications to operate over Bluetooth links

stack n Application group ¨ Consists of actual applications that use Bluetooth links ¨ They can include legacy applications as well as Bluetooth-aware applications

radio n Primarily concerned with the design of the Bluetooth transceivers n Bluetooth devices operate on 2. 4 GHz Industrial Scientific Medical band (ISM band) n Unlicensed in most countries

radio n Techniques to minimize packet loss: ¨ Frequency Hopping ¨ Adaptive power control ¨ Short data packets

radio n TDD (Time Division Duplex) ¨ The channel is divided into time slots, each 625 μs in lenght, thus the nominal hop rate is 1600 hops/s ¨ When in inquiry or page mode, it hops at 3200 hops/s with a residence time of 312. 5 μ sec

radio n n Master only transmits in odd slots Slaves only transmit in even slots

radio n FHSS (Frequency Hopping Spread Spectrum) ¨ Divides n the ISM-band into 79 1 -Mhz channels Channel 0: 2402 MHz … channel 78: 2480 MHz ¨ Communication between devices switches between available channels

radio 625 μs

radio n Three power classes defined with max output power from 1 m. W (Class 1) to 100 m. W (Class 3) ¨ power class 1 : long range (~100 m, ~100 m. W) ¨ power class 2 : mid range (~10 m, ~2. 5 m. W) ¨ power class 3 : short range (~1 m, ~1 m. W)

radio n Packet

radio n Access Code ¨ Channel Access Code (CAC) ¨ Device Access Code (DAC) ¨ Inquiry Access Code (IAC) GIAC ( Global IAC) n DIAC ( Discovery IAC ) n

radio n Packet Header ¨ AM_ADDR : the active member address in piconet ¨ TYPE : kind of code ¨ FLOW : flow control ¨ ARQN : ACK, NAK ¨ SEQN : discriminate duplication of ARQN ¨ HEC : Header verify n Payload ¨ Data header , data and CRC

radio n Kind of code ¨ Normal n ID, NULL, POLL, FHS, DM 1 ¨ SCO n HV 1, HV 2, HV 3, DV ¨ ACL n DM 1, DH 1, DM 3, DH 3, DM 5, DH 5, AUX 1

radio

radio n Error Control ¨ 1/3 FEC(Forward Error Correction) ¨ 2/3 FEC(Forward Error Correction) ¨ ARQ(Automatic Repeat Request)

radio n ARQ scheme in the ACL link

baseband n Defines how Bluetooth devices search for and connect to other devices n Responsible for channel coding/decoding, timing and managing a Bluetooth link

baseband n Master/slave ¨ Piconet : A master and the slaves piconet

baseband ¨ Scatternet : multiple piconets connected together scatternet

baseband ¨ Communication is only possible between a master and its slaves. ¨ 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 ¨ The maximum number of “parked” slaves is 255 per piconet

baseband n Device connection states

baseband n Inquire and Page

baseband n 3 power saving modes ¨ sniff : slave listens to the channel at a reduced rate (decreasing of duty cycle)-least power efficient ¨ Hold : data transfer is held for a specific time period medium power efficient ¨ park : synchronized to the piconet but does not participate in traffic

baseband n link types ¨ Voice n FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, single-slot packet size ¨ Data n link – SCO (Synchronous Connection Oriented) link – ACL (Asynchronous Connection. Less) Asynchronous, point-to-multipoint, up to 433. 9 kbit/s symmetric or 723. 2/57. 6 kbit/s asymmetric, Variable packet size (1, 3, 5 slots)

baseband

baseband

The Link Manager Protocol(LMP) n LMP manages ¨ bandwidth allocation for general data ¨ bandwidth reservation for audio traffic ¨ trust relationships between devices ¨ encryption of data ¨ control of power usage

Host Controller Interface (HCI) n This layer is not a required part of the specification n Defines a standard interface for upper level applications to access the lower layers of the stack n Its purpose is to enable interoperability among devices and the use of existing higherlevel protocols and applications

Logical Link Control and Adaption (L 2 CAP) n Deals with ¨ multiplexing of different services n RFCOMM, SDP, telephony control segmentation , reassembling of packets ¨ Quality of Service ¨ Group abstraction ¨ Create/close group, add/remove member only support ACL connection

Service Discovery Protocol (SDP) n Inquiry/response protocol for discovering services ¨ Searching for and browsing services in radio proximity ¨ Adapted to the highly dynamic environment ¨ Defines discovery only, not the usage of services ¨ Caching of discovered services

Reference n n Praktikum Mobile und Verteilte Systeme im Sommersemester 2006 ¨ Prof. Dr. C. Linnhoff-Popien, Peter Ruppel, Georg Treu Bluetooth ¨ n n n Steffen Witt and Tobias Julius Neubert Bluetooth ¨ Alessandro Leonardi Bluetooth ¨ Dr. -Ing. H. Ritter, “What is Bluetooth” ¨ Patricia Mc. Dermott-Wells