Bluetooth: 1.Applications, Technology

1. Bluetooth: 1.Applications, Technology And Performance

2. Bluetooth • A cable replacement technology • 1 Mb/s symbol rate • Range 10+ meters • Single chip radio + baseband • at low power & low price point ($5) Why not use Wireless LANs? - power - cost

3. 802.11 • Replacement for Ethernet • Supported data rates • 11, 5.5, 2, 1 Mbps; and recently up to 20+Mbps @ 2.4 GHz • up to 54 Mbps in 5.7 GHz band (802.11 a) • Range • Indoor 20 - 25 meters • Outdoor: 50 – 100 meters • Transmit power up to 100 mW • Cost: • Chipsets $ 35 – 50 • AP $200 - $1000 • PCMCIA cards $100 - $150

4. Emerging Landscape New developments are blurring the distinction • 802.11b for PDAs • Bluetooth for LAN access • Which option is technically superior ? • What market forces are at play ? • What can be said about the future ? Bluetooth 802.11 Cordless headset LAN AP

5. Bluetooth working group history • February 1998: The Bluetooth SIG is formed • promoter company group: Ericsson, IBM, Intel, Nokia, Toshiba • May 1998: Public announcement of the Bluetooth SIG • July 1999: 1.0A spec (>1,500 pages) is published • December 1999: ver. 1.0B is released • December 1999: The promoter group increases to 9 • 3Com, Lucent, Microsoft, Motorola • March 2001: ver. 1.1 is released • Aug 2001: There are 2,491+ adopter companies

6. Bluetooth: Today and Tomorrow • Will Bluetooth become a household name?

7. New Applications

8. Synchronization User benefits • Automatic synchronization of calendars, address books, business cards • Push button synchronization • Proximity operation

9. Cordless Headset User benefits • Multiple device access • Cordless phone benefits • Hands free operation Cordless headset

10. Usage scenarios examples • Data Access Points • Synchronization • Headset • Conference Table • Cordless Computer • Business Card Exchange • Instant Postcard • Computer Speakerphone

11. BluetoothTechnical overview and Protocol

12. Bluetooth Specifications IP HCI Data Single chip with RS-232, USB, or PC card interface • A hardware/software/protocol description • An application framework Applications SDP RFCOMM Audio L2CAP Link Manager Baseband RF

13. Interoperability & Profiles Applications Protocols Profiles • Represents default solution for a usage model • Vertical slice through the protocol stack • Basis for interoperability and logo requirements • Each Bluetooth device supports one or more profiles

14. Bluetooth Profiles (in version 1.2 release) • Generic Access (discovery of Bluetooth devices) • Service Discovery (establish connection and Discover available services and connects devices) • Cordless Telephone • Intercom • Serial Port • Headset • Dial-up Networking • Fax • LAN Access • Generic Object Exchange • Object Push • File Transfer • Synchronization

15. Bluetooth Protocol Stack IP Control Data Composed of protocols to allow Bluetooth devices to locate each other and to create, configure and manage both physical and logical links that allow higher layer protocols and applications to pass data through these transport protocols Applications SDP RFCOMM Audio L2CAP Link Manager Baseband Transport Protocol Group RF

16. Composed of protocols to allow Bluetooth devices to locate each other and to create, configure and manage both physical and logical links that allow higher layer protocols and applications to pass data through these transport protocols Bluetooth Radio Specification Applications IP SDP RFCOMM Control Data Audio L2CAP Link Manager Baseband RF • Radio Frequency (RF) • Sending and receiving modulated bit streams • Baseband • Defines the timing, framing • Flow control on the link. • Link Manager • Managing the connection states. • Enforcing Fairness among slaves. • Power Management • Logical Link Control &Adaptation Protocol • Handles multiplexing of higher level protocols • Segmentation & reassembly of large packets • Device discovery & QoS

17. RF - Unlicensed Radio Spectrum  12cm 5cm 33cm 26 Mhz 83.5 Mhz 125 Mhz 902 Mhz 2.4 Ghz 5.725 Ghz 2.4835 Ghz 5.785 Ghz 928 Mhz 802.11a HyperLan 802.11 Bluetooth Microwave oven cordless phones baby monitors Wireless LANs

18. RF - Bluetooth radio link • frequency hopping spread spectrum • 2.402 GHz + k MHz, k=0, …, 78 • 1,600 hops per second • GFSK modulation • 1 Mb/s symbol rate • transmit power • 0 dbm (up to 20dbm with power control) 1Mhz . . . 79 1 2 3 83.5 Mhz

19. GFSK Differences & Advantages over FSK Modulation   • Q: What are the physical Differences between an FSK & GFSK Modulator, and how do their results vary?  • A1: An FSK Modulator is much the same as a GFSK Modulator, but GFSK uses a Gaussian filter as well. In a GFSK modulator everything is the same as a FSK modulator except that before the baseband pulses (-1, 1) go into the FSK modulator, it is passed through a gaussian filter to make the pulse smoother so to limit its spectral width • A2: Gaussian filtering is one of the very standard ways for reducing the spectral width, it is called Pulse Shaping. If we use -1 for fc-fd and 1 for fc+fd, once when we jump from -1 to 1 or 1 to -1, the modulated waveform changes rapidly, which introduces large out-of-band spectrum. If we change the pulse going from -1 to 1 as -1, -.98, -.93 ..... .96, .99, 1, and we use this smoother pulse to modulate the carrier, the out-of-band spectrum will be reduced.

20. Middleware Protocol Group IP Control Data 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. Applications SDP RFCOMM Middleware Protocol Group Middleware Protocol Group Audio L2CAP Link Manager Baseband RF

21. 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(Radio Frequency Communications) • Cable replacement protocol, emulation of serial ports over wireless network

22. Application Group IP Control Data Applications Application Group SDP RFCOMM Consists of Bluetooth aware as well as un-aware applications. Audio L2CAP Link Manager Baseband RF

23. Review Format And Power Mode

24. Master - Slave • Master • Device in Piconet whose clock and hopping sequence are used to synchronize all other devices (slaves) in the Piconet. • It also carries out Paging procedure and also Connection Establishment. • Slaves • Units within the piconet that are syncronized to the master via its clock and hopping sequence. • After connetion establishment, Slaves are assigned a temporary 3 bit member address to reduce the no. of addresing bits required

25. Piconets m s • 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). • Hopping pattern is determined by the master. m s s s

26. Piconet Structure Master Active Slave Parked Slave Standby

27. Physical Link Types • Synchronous Connection Oriented (SCO) • Point to Point Full Duplex between Master & Slave • Established once by master & kept alive till released by Master • Typically used for Voice connection ( to guarantee continuity ) • Master reserves slots used for SCO link on the channel to preserve time sensitive information • Asynchronous Connection Link (ACL) • It is a momentary link between master and slave. • No slots are reserved. • It is a Point to Multipoint connection. • Symmetric & Asymmetric links possible

28. Packet Types Data/voice packets Control packets Voice data ID* Null Poll FHS DM1 HV1 HV2 HV3 DV DH1 DH3 DH5 DM1 DM3 DM5 AccessCode Header Payload

29. Packet Structure 0 - 2744 bits 54 bits 72 bits Access Code Header Payload header Data Voice CRC No CRC No retries ARQ FEC (optional) FEC (optional)

30. Access Code • Purpose • Synchronization • DC offset compensation • Identification • Signaling • Types • Channel Access Code (CAC) • Identifies a piconet. • Device Access Code (DAC) • Used for signalling procedures like paging and response paging. • Inquiry Access Code (IAC) • General IAC is common to all devices, Dedicated IAC is for a dedicated group of Bluetooth devices that share a common characteristic.

31. Packet Header • Addressing ( 3 bits ) • Packet type (4 bits ) • Flow Control ( 1 bit ) • 1-bit ARQ • Sequencing ( 1 bit ) • HEC ( 8 bit ) For filtering retransmitted packets Verify header integrity

32. Connection State Machine Inquiry Page Standby Connected Transmit data Park Sniff Hold

33. Connection State Machine (contd.) • Inquiry Scan • A device that wants to be discovered will periodically enter this mode and listen for inquiry packets. • Inquiry • Device sends an Inquiry packet addressed to GIAC or DIAC • Transmission is repeated on the inquiry hop sequence of frequencies. • Inquiry Response • When an inquiry message is received in the inquiry scan state, a response packet (FHS) containing the responding device address must be sent after a random number of slots.

34. Connection State Machine (contd.) Inquiry Response

35. Connection State Machine (contd.) • Page • The master uses the clock information, about the slave to be paged, to determine where in the hop sequence, the slave might be listening in the page scan mode. • The master sends a page message • Page Scan • The page scan substate can be entered by the slave from the standby state or the connection state. It listens to packets addressed to its DAC. • Page Response • On receiving the page message, the slave enters the slave page response substate. It sends back a page response consisting of its ID packet which contains its DAC, at the frequency for the next slot from the one in which page message was received.

36. Security • Security Measures • Limited/Restricted Access to authorized users. • Both 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. • Security values • Device Address-Public • Authentication Key(128 bits)-Private • Encryption Key(8-128 bits)-Private • Random Number

37. Frequency Hop Spread-Spectrum • Bluetooth channel is represented by a pseudo random hopping sequence through the entire 79 RF frequencies • Nominal hop rate of 1600 hops per second • Channel Spacing is 1 MHz

38. Time-Division Duplex Scheme • Bluetooth devices use a Time-Division Duplex (TDD) 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 b/t 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

39. Review of basic concepts

40. Baseband Applications IP IP SDP RFCOMM Control Control Data Data Audio L2CAP Link Manager Baseband RF Applications SDP RFCOMM Audio L2CAP Link Manager Baseband RF

41. Bluetooth Physical link m s m s s • Piconet • Master can connect to 7 slaves • Each piconet has max capacity =1 Mbps • hopping pattern is determined by the master s • Point to point link • master - slave relationship • radios can function as masters or slaves

42. Connection Setup • Inquiry - scan protocol • to learn about the clock offset and device address of other nodes in proximity

43. Inquiry on time axis Inquiry hopping sequence f1 f2 Slave1 Master Slave2

44. Piconet formation Master Active Slave Parked Slave Standby • Page - scan protocol • to establish links with nodes in proximity

45. Addressing • Bluetooth device address (BD_ADDR) • 48 bit IEEE MAC address • Active Member address (AM_ADDR) (see power mode) • 3 bits active slave address • all zero broadcast address • Parked Member address (PM_ADDR) (see power mode) • 8 bit parked slave address

46. Piconet channel FH/TDD f5 f1 f4 f3 f2 f6 m s1 s2 625 sec 1600 hops/sec

47. Multi slot packets FH/TDD f1 f5 f4 f6 m s1 s2 625 µsec Data rate depends on type of packet

48. Physical Link Types ACL ACL ACL ACL ACL ACL SCO SCO SCO SCO SCO SCO • Synchronous Connection Oriented (SCO) Link • slot reservation at fixed intervals • Asynchronous Connection-less (ACL) Link • Polling access method m s1 s2

49. Packet Types Data/voice packets Control packets Voice data ID* Null Poll FHS DM1 HV1 HV2 HV3 DV DH1 DH3 DH5 DM1 DM3 DM5

50. Packet Format 54 bits 72 bits 0 - 2744 bits Access code Header Payload header Data Voice CRC No CRC No retries ARQ FEC (optional) FEC (optional) 625 µs master slave