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21IEEE802151Bluetooth.pdf

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1、Bluetooth TechnologyBluetooth - 2Agenda Bluetooth Overview Bluetooth Radio Bluetooth Baseband Host Control Interface (HCI) L2CAP Service Discovery Protocol Bluetooth ProfileBluetooth - 3Bluetooth OverviewBluetooth - 4Whats Bluetooth? Harald Blaatand “Bluetooth” II King of Denmark 940-981 Son of Gorm

2、 the Old (King of Denmark) and Thyra Danebod (daughter of King Ethelred of England) Harald controlled Denmark and Norway Harald thinks “notebooks”and “cellular phones” should seamlessly communicateBluetooth - 5 1997 - Designed by Ericsson 1998.2 - Established the Special interest group (form SIG 1)

3、Ericsson, Nokia, IBM, Toshiba, Intel 1998.5 - Bluetooth Consortium is established formally 1999.7 - Bluetooth v1.0 2002 - IEEE 802.15.1 2004 - Bluetooth v2.0 2005.6 - Revision of IEEE 802.15.1-2002Bluetooth HistoryBluetooth - 6Personal Ad-hoc NetworksCable ReplacementLandlineData/Voice Access Points

4、(internet access)voice application is most importantBluetooth Major ApplicationsBluetooth - 7Usage Model (Internet Bridge) Mobile browsing in the room (on sofa) or in the officeBluetooth - 8Usage Model (Ultimate Headset) Keep your hands freeBluetooth - 9Usage Model (Synchronizer) Background synchron

5、ization PDA Cellular phone NotebookBluetooth - 10Usage Model (Wireless Workspace) Wirelessly connected computer peripheralsBluetooth - 11 Conference Table Share and exchange data in the classroomUsage Model (Conference Table)Bluetooth - 12Usage Model (Three in One Phone) One phone three functions In

6、tercom Coreless CellularBluetooth - 13Bluetooth Products Blue-Dongle Blue-Connect BluePort Bluetooth printer Bluetooth modemBluetooth - 14Key Characteristics Low cost Market considerations Low power consumption Portable device consideration Short Range Unlicensed used ISM band used Robust operation

7、Fast frequency hopping Short packet length Multiple links Mixed voice and data Sized 0.5 squire inchesBluetooth - 15Bluetooth Protocol Stack(Single chip with RS-232,USB or PC card interface)RFBasebandAudioLink ManagerL2CAPDataSDPRFCOMMIPControlApplicationsBluetooth chipFirmwareApplicationsBluetooth

8、- 16Bluetooth Specifications 2.4 GHz ISM Unlicensed band Frequency Hopping Spread Spectrum (FHSS) Interference avoidance 23/79 channels 1MHzper channel 1 Mbps link rate (GFSK modulation) Fast frequency hopping and short data packets avoid interference Nominally hops at 1600 times a second (625 us pe

9、r hop) 2.5 hops/sec in IEEE 802.11 3200 times a second during inquiry and paging modes Bluetooth - 17MMSS SSPsbsbPPNetwork Topology Radio Designation Connected radios can be master or slave Radios are symmetric (same radio can be master or slave)Bluetooth - 18Network Topology (contd) Piconet Master

10、can connect to 7 simultaneous or 200+ active slaves per piconet Each piconet has maximum capacity (1 Msps and 1 Mbps) Unique hopping pattern/ID Scatternet High capacity system Minimal impact with up to 10 piconets within range Radios can share piconets!Bluetooth - 19Piconet vs. Scatternet A scattern

11、et contains two piconetsScatternetPiconetPiconetMasterSlaveSlaveSlaveSlaveSlaveMasterBluetooth - 20Piconet vs. Scatternet (contd)point-to-point(piconet)multi-point(piconet)scatternetMaster host Slave hostBluetooth - 21Bluetooth RadioBluetooth - 22ISM Unlicensed Band2.4GHz2.402Guard band Guard band2.

12、48 2.48352.402-2.480 GHz79 hopping channelsISM unlicensed bandLicensedband79 channels in 2.4GHz (in USA and most Europe)LicensedbandBluetooth - 23Transmit PowerN/A1 mW (0 dBm)30.25 mW (-6 dBm)2.5 mW (4 dBm)21 mW (0 dB)100 mW (20 dBm)1Min OutputMax OutputPower Class Power 1mW (class 3)3% power of cel

13、lular phone10 meters of transmission distance or 100m by PA Power 100mW(class 1)100 meters of transmission distance Transmit power and range 0 dbm (up to 20dbm with power control) 10-100mBluetooth - 24Frequency HoppingTimeFrequency078Bluetooth - 25FHSSDataSourceHoppingCodeGenerator+d(t)DigitalModula

14、torFrequencysynthesizerFront-endFilter+FrequencysynthesizerDataDetectord(t)Local hoppingcode generatorReceiverTransmitterBluetooth - 26Clock Synchronizationsame hopping sequence3, 56, 7, 23, 44, MasterBD_ADDRSlave Native CLK+offsetMaster clockBD_ADDR CLKN (Native Clock) Exist in each bluetooth devic

15、e The counter can not be frozen and adjusted Clock resolution : 312.5us (half slot time : used for paging/inquiry procedures) slave follows its master CLKN to hop in a piconet Master need inform the slave its CLKN and BD_ADDR Slave adds offset into its CLKN to synchronize with masterBluetooth - 27Cl

16、ock Synchronization (contd)estimated slaves hopping sequence3, 56, 7, 23, 44, SlaveBD_ADDRMaster CLKN+Slave clockBD_ADDRpagingSlave CLKEoffset CLKE (Estimated Clock) Is used when master pages a known slave device (has been inquired) Master uses the slaves BD_ADDR to estimate the slaves CLKNBluetooth

17、 - 28Modulation and Symbol Rate Symbol Rate : 1M symbols/sec (1MHz) GFSK (Gaussian Frequency Shift Keying) Binary One (1) : Positive frequency deviation Binary Zero (0) : Negative frequency deviation Maximum frequency deviation Between 140kHz and 175kHzfo fo+ffo-fFrequencyMagnitudeBluetooth - 29Adap

18、tive Frequency Hopping When no interference is detected, hop over theentire frequency band If interference is detected at a level which cause packet error Actively avoid these frequency hop locations This technique is currently legal for Class 3 Bluetooth units Hop locations must be maintainedBluetooth - 30Bluetooth Baseband

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