1. Mohamed Mokdad Ecole d’Ingénieurs de Bienne
Bluetooth
Mohamed Mokdad
Ecole d’Ingénieurs de Bienne

2. What is Bluetooth? Data transmission standard
Between different kinds of terminals
E.g. PC, Printer, PDA, Phone,
Radio Link
Bitrate: Up to 1 mbps
Security: It’s secured
It’s not intended for permanent connection
Cable replacement
Support different kind of services data and voice

3. History Ericsson starts developping it in 1994
Other joined: IBM, Nokia, etc
The group is named: Bluetooth SIG
SIG = Special Interest Group
Bluetooth SIG
Specifications
Profiles
Comme pour DECT il y a un standard générique et des profils
Compétiteur IEEE Sur la base de Bluettoth
PAN = Personal Area Network
BT et PAN incompatbles + PAN seulement jusqu’à la couches 2

4. How it works? Radio link between 2 terminals
On short distances up to 10 meters
Special arrangements up to 100 meters
Theoritical Bitrate up to 720 kbps
1 Master & 1+ Slave terminals (up to 7)
Link: only Master to Slave
No slave to slave links
Frequency Hopping
Produit concurrent de WLAN
Frequency Hopping as in WLAN

5. The Applications PC to PDA synchronisation Printing everywhere
Headsets
Mobile phone to PDA
COM Devices …
WLAN like configuration
Existe aussi sous forme d’interface externe pour port Seriel, USB et autres
Je n’ai pas encore vu pour port Ethernet

6. Components Overview
3 main components en plus du host

7. The architecture: Piconet
Single slave operation
Une vue d’ensemble de l’architecture bluetooth
Différentes configurations
Un réseau = un master et plusieurs slaves
Piconet = 1 Master + 7 Salves actifs et 255 Slaves parked
Multi slaves operation
Scatternet operation

8. Specs – Radio Channel 2.4 GHz – Bandwidth 79 MHz
1 MHz frequency hops, i.e. 79 hops
Not everywhere available spectrum
E.g. France: limitation to 23 MHz bandwidth
Reach of 10 m with 2.5 mW
2.5 mW ~ 4 dBm, i.e. Log(2.5mW/1mW)
The cell is the Piconet
3 power classes: 1, 2.5 & 100 mW
Limitation spectrals dans certains pays comme pour le WLAN
3 class of power
3 – 1mW
2 – 2.5 mW
1 – 100 mW = WLAN en Europe
Qui s’expriment en dBm
dBm = Log(mW/1mW)
Rappel: Gain d’une liaison aérienne
Pr = Pt + Gt + Ga + Gr

9. Radio interface features
Power control with RSSI – LMP
Receiver Signal Strength Indicator (dBm)
Allows power adjustment for Class 1 (High)
Optional for Power Classes 2 and 3
Key features of Bluetooth
Robustness, low complexity
low power, low cost.
Frame number 0 to & 227
Master sends in even slots (0, 2, 4, …)
RSSI existe aussi pour GSM C'est ce qui permet le changement de cellule ou le handover

10. Physical Layer Channel divided in 625 ms slots
Every a different frequency hop
A packet can be
Less then one slot
One slot
More then one slot (up to five)
Next packet starts on next slot
One packet per frequency hop
Les grandeurs des paquets et leur transport sur les slots

11. Packets & Hops Timing des paquets entre Master et Slave
Les paquets commencent sur des slotss
2 types de slots: Master to Slave and Slave to Master

12. Packets & Hops Les paquets peuvent être plus longs que les slots
Remarquer la numérotation des slots
Le master envoie toujours sur les slots pairs: 0, 2, 4, ....

13. Transmission mode - SCO
Synchronous Connection-Oriented
SCO
Point to point connection in the Piconet
Regular reserved transmission slots
Speech 64 kbps
Maximum of 3 Master-Slave simultaneous connections
2 modes de transmission Connectin oriented and Connectionless
Similaire à l'ATM transmission synchrone sous forme de paquets
Regular slots
Reserved slots
Synchronous/Asynchronous: c'est quoi?
Synchrone il existe une synchronisation entre les emeteur et recepteur
Asnchrone Pas besoin de timing pour envoyer mes bytes sur uune interface serielle
There is a start bit, s top bit, # of data bits
Error checking and handshake is something different

14. Transmission mode - ACL
Asynchronous Connection-Less
ACL
One single connection
No slot reservation
More then one the same time
And with more then one slave
Le mode transmission de paquets conventionel sous IP
Pas de limitation sur le nombre des slaves

15. SCO & ACL
Red: the SCO cells
Green and Blue the ACL

16. The packet Access Code - Channel Access Code: Identifies the Piconet
- Device Access Code:     Identifies the access type
Inquiry Access Code:     Identifies the request
Header for addressing, error correction and flow control
Payload for Data 
Access code en plus du monde IP
Channel Access Code utilisé dans tous les paquets échangés sur le piconet
Device Access Code usage special, e.g paging
Inquiry Access Code découverte du voisinage, service discovery

17. Overview of major states
Standby state
Default state
Low power comsuption
No interaction with any other terminal
Synchronised (Clock active)
Connection state
Dialog state
Master clock for synchronisation
The master synchronise the piconet
C'est le chef d'orchestre du piconet Il distribue l'horloge

18. 2 états majeurs et
7 sous états
Les sous états servent à la configuration du piconet, ajout et suppression de slaves

19. Connection state modes
Active mode
Participating to a connection
Sniff mode
Reduction of the slave listening activity
Hold mode
No ACL support, but just SCO support
Frees capacity for other slaves
Park mode
Remains synchronised and keeps addresses
Dans les états il existe des modes

20. Connection modes
Illustration graphque

21. Hold Mode
Le slave est exclus de la communication pendant une durée déterminée

22. Sniff Mode
Idem avec une fonction de sniffing à intervalle régulier

23. The protocol stack HCI = Host Controller Interface Bluetooth Host
Bluetooth Device or hardware
HCI entre les 2, n'est pas nécessaire si Bluetooth HW intégré dans BT host

24. Base Band Physical channels Physical links Packets Error correction
Time 625 ms
Physical links
SCO and ACL
Packets
Access code, packet header and types
Error correction
1/3, 2/3 and ARQ scheme
Pas de details sur la correction d’erreurs
BT travaille aussi dans l'espace WLAN et alors?
1/3
Simple répétition (3) du header
2/3
Plus compliqué et utilise le code de Hamming
Pour les données et pas pour le header
ARQ
Avec Automatic Repeat Request
S'utilise avec un CRC (Cyclic Redundancy Check)

25. Logical channels Logical channels (5) LC = Link Control
Low level link control: ARQ, Flow, etc.
LM = Link Manager
Peer protocol between Link Mgr (Master/Slave)
UA = User Asynchronous Data
Different clocks & Synchronization per byte
UI = User Isochronous Data
Clock in data & mainly no error checking
US = User Synchronous Data
Synchronized clocks & Error checking
Les canaux logiques
Isochronous # Asynchronous
Isochronous lié au temps, e.g. audio compressé
Asynchronous lié à la fiabilité de la transmission, e.g. data

26. Logical channels UA/UI & US
Carried over ACL links US
Carried over SCO links
LC mapped in the packet header
The other in the payload
Access Code et Header longueur fixe
Payload variable

27. Packet Hierarchy
Access code
Synchronisaiton, DC offset and idenification
Channel Access Code – identifie le Piconet
Device Access Code – identifie le device
Inquiry Access Code – identifie le device discovery
Header
Link Control Information
Device address, Type, Flow, Ack, Sequence numbering & error check
Payload
Payload header, Payload & CRC
PSM: Protocol Service Multiplexer, i.e. SPD, RFCOMM or TCP

28. ACL Packets
Look at the speed

29. SCO PAckets
Noter la correction d'erreur
Pas de répétition

30. Packets Transmit & Receive
Transmit & Receive Routines
The standard makes suggestion
There is no obligation to implement
It looks like V.24 interface
Transmit Buffer
Receive Buffer …
It’s however much more complicated
BT définit les procédures de transmission et de réception de paquets à titre informel

31. Link Manager Protocol LMP = Link Manager Protocol
Vision des composants sous forme de stack

32. Link Manager Protocol Link Setup Link Control Link Security LM PDU
Link Manager Protocol Data Unit
LM PDU always sent in the payload and
Always as single-slot packets
Les fonctions de LM
Services classiques d'un link manager
LC in the header

33. The Procedures General response messages Authentication Pairing
Change Link Key
Change Current Link Key
Encryption
Switch of Master-Slave Role
QoS
Les procédures à disposition

34. Pairing No link key available Generate one based on
Random number, BD_ADDR, PIN
Initiator and Responder
Reject or
Accept and create link key
Pairing avant l'authetification
Link key est nécessaire à l'authentification

35. Authentication Secret Key Claimant and Verifier
Based on Challenge, BD_ADDR, secret link key
Claimant and Verifier
Has key
Has no key
2 entités: claimant et verifier
Le verifier défie le claimant de répondre à un input

36. L2CAP Logical Link Control & Adaptation Protocol
Higher layer protocols
Packet Segmentation & Reassembly (SAR)
Multiplexing
QoS
Supports ACL and no SCO Links
Simplicity and low overhead
Applicable to equipment with low power resources: PDAs, Cellular phones, …
Protocole sur le LMP
SCO pas à travers le L2CAP

37. Stack The hierarchy Radio – Baseband – LMP – L2CAP
RFCOMM émulation de port sériel
OBEX = OBject EXchange Protocole
TCS BIN = Telephony Control protocole Specification pour la téléphonie
À noter que l'audi passe directement sur le canal physique

38. L2CAP does not support
L2CAP does not transport audio designated for SCO links.
L2CAP performs no retransmissions or checksum calculations.
L2CAP does not perform any CRC Calculation

39. Payload Format LMP = 1 slot packets L2CAP = 1 or more slots packets
Le LMP sont des trames courtes
L2CAP peut avoir plusieurs paquets
L_CH définit le contenu du message
LMP = 1 slot packets
L2CAP = 1 or more slots packets

40. Channel Coding To be noted 10 = Start of L2CAP packet
01 = Continuation of L2CAP packet

41. Channels Summary
Noter l'attribution de ID différents (local et remote) pour le même canal

42. Channels types Les types de canaux (Local et remote)
Signalisation + SCO
Signalisation + ACL
Signalisation seulement
CID = Channel Identifier

43. Channels types Connection oriented data channels
Both ways connection
Normal CID
Connectionless channels
One way channel
Reserved CID
E.g Signaling
Signaling channel is mandatory
Noter la présence de CID à usage reservé

44. L2CAP Services 8 5 4 1 2 7 6 3
Rappel
Ligne rouge = séparation entre 2 devices BT

45. Segmentation
Rappel sur la segmentation
LeCAP peut dialoguer avec une interface HCI ou directement avec le baseband
Segmentations ifféerentes
L2CAP over Baseband: segment in Baseband packets to send over the air
L2CAP over HCI: segment in block sized chunks to send to the HCI
This will segment to Baseband packet to send over the air
The scenario is: L2CAP to Baseband to L2CAP

46. USB based Example Exemple de transmission sur port USB
2 niveaux de segmentation
L2CAP à HCI
HCI à USB

47. Profiles Bluetooth SIG Profiles Devices Interoperability
Different profiles
Devices Interoperability
Not all Bluetooth devices can interoperate
Service and use case
Specify the supported services
Describe the air interface
For the profile
Cela rappelle DECT

48. Type of support Mandatory Optional Conditional eXcluded Not Applicable
Define profile's capabilities
Optional
Define profile's capabilities that can be used
Conditional
In conjunction with some other capability
eXcluded
Should not be used in this profile
Not Applicable
La fonctionalité supportée est de différents types
Entre autre Excluded

49. Profiles GENERIC ACCESS - @ least SERVICE DISCOVERY APPLICATION
CORDLESS TELEPHONY
INTERCOM
SERIAL PORT
HEADSET
DIAL-UP NETWORKING
FAX
LAN ACCESS
GENERIC OBJECT EXCHANGE
OBJECT PUSH
FILE TRANSFER
SYNCHRONIZATION
Liste des profiles définis par la norme

50. Profile description Scope Dependencies Stack The protocols
What is its usage: service and use case
Dependencies
What other profiles are required
Stack
Which element of the stack are involved
The protocols
@ the different layers: LM, L2CAP, …
Définiton d'un profile

51. E.g. Generic Profile Stack
exemple

52. E.g. Dial-Up Networking Stack
Exemple of RFCOMM profile

53. E.g. Generic Object Ex. Stack
Exemple of profile dependancy

54. Generic Access
This profile defines the generic procedures related to discovery of Bluetooth devices (idle mode procedures) and link management aspects of connecting to Bluetooth devices (connecting mode procedures). It also defines procedures related to use of different security levels. In addition, this profile includes common format requirements for parameters accessible on the user interface level.
BT discovery of services et LM

55. Service Discovery Application
This document defines the features and procedures for an application in a Bluetooth device to discover services registered in other Bluetooth devices and retrieve any desired available information pertinent to these services.
BT discovery of services et
Et récupération d'information

56. Headset
This profile defines the requirements for Bluetooth devices necessary to support the Headset use case. The requirements are expressed in terms of end-user services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the Headset use case.
No comment

57. Serial Port
This profile defines the requirements for Bluetooth devices necessary for setting up emulated serial cable connections using RFCOMM between two peer devices. The requirements are expressed in terms of services provided to applications, and by defining the features and procedures that are required for interoperability between Bluetooth devices.
Émulation de communication sérielle
Sérielle dans le sens RS232

58. Dial-Up networking
This profile defines the requirements for Bluetooth devices necessary for the support of the Dial-up Networking use case. The requirements are expressed in terms of enduser services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the Dialup Networking use case.
Dial-up du style modem

59. Generic Object Exchange
This profile defines the requirements for Bluetooth devices necessary for the support of the object exchange usage models. The requirements are expressed by defining the features and procedures that are required for interoperability between Bluetooth devices in the object exchange usage models.
C'est un profile de basse couche
Underlying profile

60. Object Push
This application profile defines the application requirements for Bluetooth devices necessary for the support of the Object Push usage model. The requirements are expressed in terms of end-user services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the Object Push usage model.
Écrire sur un terminal
Objects examples: Business Card, Appointment

61. File Transfer
This application profile defines the application requirements for Bluetooth devices necessary for the support of the File Transfer usage model. The requirements are expressed in terms of end-user services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the File Transfer usage model.
FTP
Que ne peut-on pas faire avec BT?

62. Synchronization
This application profile defines the application requirements for Bluetooth devices necessary for the support of the Synchronization usage model. The requirements are expressed in terms of end-user services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the Synchronization usage model.
Synchronisaion of objects
Synchronization of objects

63. LAN Access
This document is a LAN Access Profile for Bluetooth devices. Firstly, this profile defines how Bluetooth-enabled devices can access the services of a LAN using PPP. Secondly, this profile shows how the same PPP mechanisms are used to form a network consisting of two Bluetooth-enabled devices.
LAN
PPP = Point-to-Point Protocol

64. Fax
This profile defines the requirements for Bluetooth devices necessary for the support of the Fax use case. The requirements are expressed in terms of end-user services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the Fax use case.
Fax

65. Cordless Telephony
This profile defines the features and procedures that are required for interoperability between different units active in the ‘3-in-1 phone’ use case. The scope of this profile includes the following layers/protocols/ profiles: Bluetooth Baseband, Link Manager Protocol, L2CAP, Service Discovery Protocol, Telephony Control Protocol Specification (TCS-Binary) and the General Access Profile.
This is not headset profile

66. Intercom
This profile defines the requirements for Bluetooth devices necessary for the support of the intercom functionality within the 3-in-1 phone use case. The requirements are expressed in terms of end-user services, and by defining the features and procedures that are required for interoperability between Bluetooth devices in the 3-in-1 phone use case.
Special usage

68. Data whitening Randomize the data Minimize DC bias in the packet
No redundant patterns
Minimize DC bias in the packet
To reduce the DC offset
i.e. DC value tends to 0
Generated with a polynomial
As for CRC-16, CRC-32
Parenthèse sur le data whitening

69. Packet Hierarchy
Hierarchie
Définition du payload
PSM: Protocol Service Multiplexer, i.e. SPD, RFCOMM or TCP