蓝牙技术课件

An Introduction to An Introduction to BLUETOOTH TECHNOLOGYBLUETOOTH TECHNOLOGY *1 CONTENT Overview of Bluetooth History The Bluetooth Specifications Typical Bluetooth Scenario Protocols Profiles Security Comparison with other technologies Future of Bluetooth Summary Date2 Example : The Networked Home Date3 What is Bluetooth? “Bluetooth wireless technology is an open specification for a low-cost, low-power, short-range radio technology for ad-hoc wireless communication of voice and data anywhere in the world.” One of the first modules (Ericsson)A recent module Date4 Ultimate Headset Date5 Cordless Computer Date6 Bluetooth Goals & Vision Originally conceived as a cable replacement technology Short-Range Wireless Solutions Open Specification Voice and Data Capability Worldwide Usability Other usage models began to develop: Personal Area Network (PAN) Ad-hoc networks Data/voice access points Wireless telematics Date7 Overview of Bluetooth History What is Bluetooth? Bluetooth is a short-range wireless communications technology. Why this name? It was taken from the 10th century Danish King Harald Blatand who unified Denmark and Norway. When does it appear? 1994 Ericsson study on a wireless technology to link mobile phones & accessories. 5 companies joined to form the Bluetooth Special Interest Group (SIG) in 1998. First specification released in July 1999. Date8 Timeline 1994 : Ericsson study complete / vision 1995 : Engineering work begins 1997 : Intel agrees to collaborate 1998 : Bluetooth SIG formed: Ericsson, Intel, IBM, Nokia & Toshiba 1999 : Bluetooth Specification 1.0A SIG promoter group expanded: 3Com, Lucent, Microsoft & Motorola 2000 : Bluetooth Specification 1.0B, 2000+ adopters 2001 : First retail products released, Specification 1.1 2003 : Bluetooth Specification 1.2 2005 : Bluetooth Specification 2.0 (?) Date9 Special Interest Group Date10 Technical features Connection Type Spread Spectrum (Frequency Hopping) & Time Division Duplex (1600 hops/sec) Spectrum 2.4 GHz ISM Open Band (79 MHz of spectrum = 79 channels) ModulationGaussian Frequency Shift Keying Transmission Power 1 mw 100 mw Data Rate1 Mbps Range 30 ft Supported Stations8 devices Data Security Authentication Key 128 bit key Data Security Encryption Key 8-128 bits (configurable) Module size9 x 9 mm Date11 Bluetooth FHSS Employs frequency hopping spread spectrum Reduce interference with other devices Pseudorandom hopping 1600 hops/sec- time slot is defined as 625 microseconds Packet 1-5 time slots long Date12 Time-Division Duplex Scheme Channel is divided into consecutive slots (each 625 s) One packet can be transmitted per slot Subsequent slots are alternatively used for transmitting and receiving Strict alternation of slots between the master and the slaves Master can send packets to a slave only in EVEN slots Slave can send packets to the master only in the ODD slots Date13 Classification POWERRANGE CLASS I20 dBm100 m CLASS II0-4 dBm10 m CLASS III0 dBm1 m Classification of devices on the basis of Power dissipated & corresponding maximum Range. Date14 Typical Bluetooth Scenario Bluetooth will support wireless point-to-point and point-to-multipoint (broadcast) between devices in a piconet. Point to Point Link Master - slave relationship Bluetooth devices can function as masters or slaves Piconet It is the network formed by a Master and one or more slaves (max 7) Each piconet is defined by a different hopping channel to which users synchronize to Each piconet has max capacity (1 Mbps) ms sss m Date15 Piconet Structure Master Active Slave Parked Slave Standby All devices in piconet hop together. Masters ID and masters clock determines frequency hopping sequence & phase. Date16 Ad-hoc Network the Scatternet Inter-piconet communication Up to 10 piconets in a scatternet Multiple piconets can operate within same physical space This is an ad-hoc, peer to peer (P2P) network Date17 Bluetooth Protocol Stack Date18 Baseband Date19 Baseband Addressing Bluetooth device address (BD_ADDR) 48 bit IEEE MAC address Active Member address (AM_ADDR) 3 bits active slave address all zero broadcast address Parked Member address (PM_ADDR) 8 bit parked slave address This MAC address is split into three parts The Non-significant Address Part (NAP) Used for encryption seed The Upper Address part (UAP) Used for error correction seed initialization & FH sequence generation The Lower Address Part (LAP) Used for FH sequence generation Date20 Packet Structure Voice No CRC DataCRCheader ARQ FEC (optional) FEC (optional) 72 bits54 bits 0 - 2744 bits Access Code HeaderPayload Date21 Connection State Machine Standby InquiryPage Connected Transmit data ParkHoldSniff Date22 Channel Establishment There are two managed situations A device knows the parameters of the other It follows paging process No knowledge about the other Then it follows inquiring & paging process Two main states and sub- states Standby (no interaction) Connection (working) Seven more sub-states for attaching slaves & connection establishment Connection State Machine Date23 Channel Establishment (contd.) Seven sub-states Inquiry Inquiry scan Inquiry response Page Page scan Master response Slave response Date24 Link Manager Protocol Date25 Link Manager Protocol The Link Manager carries out link setup, authentication & link configuration. Channel Control All the work related to the channel control is managed by the master The master uses polling process for this The master is the first device which starts the connection This roles can change (master-slave role switch) Date26 Service provided to the higher layer: L2CAP provides connection-oriented and connectionless data services to upper layer protocols Protocol multiplexing and demultiplexing capabilities Segmentation & reassembly of large packets L2CAP permits higher level protocols and applications to transmit and receive L2CAP data packets up to 64 kilobytes in length. L2CAP Date27 Middleware Protocol Group RF Baseband Audio Link Manager L2CAP Data SDP RFCOMM IP Control Applications Middleware Protocol Group Additional transport protocols to allow existing and new applications to operate over Bluetooth. Packet based telephony control signaling protocol also present. Also includes Service Discovery Protocol. Date28 Middleware Protocol Group (contd.) Service Discovery Protocol (SDP) Means for applications to discover device info, services and its characteristics. TCP/IP Network Protocols for packet data communication, routing. RFCOMM Cable replacement protocol, emulation of serial ports over wireless network. Date29 IP Over Bluetooth IP over Bluetooth v 1.0 Date30 IP Over Bluetooth IP over Bluetooth v 1.1 Date31 File Transfer Profile Profile provides: Enhanced client-server interactions: - browse, create, transfer folders - browse, pull, push, delete files Date32 Headset Profile Profile provides: Both devices must provide capability to initiate connection & accept/terminate calls. Volume can be controlled from either device. Audio gateway can notify headset of an incoming call. Date33 Core Bluetooth Products Notebook PCs & Desktop computers Printers PDAs Other handheld devices Cell phones Wireless peripherals: Headsets Cameras CD Player TV/VCR/DVD Access Points Telephone Answering Devices Cordless Phones Cars Date34 Other Products 2004 Toyota Prius & Lexus LS 430 hands free calls Digital Pulse Oximetry System Toshiba Washer & Dryer Nokia N-gage Date35 Security Security Measures Link Level Encryption & Authentication. Personal Identification Numbers (PIN) for device access. Long encryption keys are used (128 bit keys). These keys are not transmitted over wireless. Other parameters are transmitted over wireless which in combination with certain information known to the device, can generate the keys. Further encryption can be done at the application layer. Date36 A Comparison WLAN Date37 Bluetooth vs. IrD Bluetooth Point to Multipoint Data & Voice Easier Synchronization due to omni -directional and no LOS requirement Devices can be mobile Range 10 m IrD Point to point Intended for Data Communication Infrared, LOS communication Can not penetrate solid objects Both devices must be stationary, for synchronization Range 1 m Date38 Bluetooth: Today & Tomorrow Date39 Will Bluetoo