1. IT351: Mobile & Wireless Computing
Wireless Personal Area Networks (WPAN)
Part-2: IEEE Bluetooth
Objectives:
To introduce Ad Hoc networking and discuss its application domain.
To provide a detailed study of the Bluetooth Wireless Technology including its architecture and protocol.

2. Outline Motivation History Application and usage scenarios
Network architecture
Piconets
Scatternets
Protocol stack
Core protocols
Cable replacement and telephony control protocols
Profiles
Future developments
Wi-Fi vs. Bluetooth

3. Bluetooth - Motivation
Freie Universität Berlin
Institut of Computer Science
Mobile Communications
2002
Bluetooth - Motivation
A technology that aims at ad-hoc piconets -- LAN with very limited coverage without the need for infrastructure
To connect small devices in close proximity (about 10 m)
The envisaged gross data rate is 1 Mbits/s
Both asynchronous (data) and synchronous (voice) services
Transceiver should be very cheap
Low power consumption chip
Replace IrDA and solve its main problems:
limited range – 2m for built-in interfaces
line of sight
usually limited to two users, only point-to-point connections are supported
no internet working functions
has no MAC
Big advantage: COST
Prof. Dr.-Ing. Jochen Schiller

4. Freie Universität Berlin Institut of Computer Science
Mobile Communications
2002
Bluetooth
(was: )
History
1994: Ericsson (Mattison/Haartsen) initiated “MC-link” (multi communicator link) project
Renaming of the project: Bluetooth according to Harald “Blåtand” Gormsen [son of Gorm], King of Denmark in the 10th century
1998: foundation of Bluetooth SIG,
1999: erection of a rune stone at Ercisson/Lund ;-)
2001: first consumer products for mass market, spec. version 1.1 released
2005: 5 million chips/week
Special Interest Group
Original founding members: Ericsson, Intel, IBM, Nokia, Toshiba
Added promoters: 3Com, Agere (was: Lucent), Microsoft, Motorola
> members
Common specification and certification of products
Same time, an IEEE study group for a WPAN specifications started IEEE – Requirements fulfilled by Bluetooth
Prof. Dr.-Ing. Jochen Schiller

5. Freie Universität Berlin Institut of Computer Science
Mobile Communications
2002
History and hi-tech…
1999:
Ericsson mobile communications AB reste denna sten till minne av Harald Blåtand, som fick ge sitt namn åt en ny teknologi för trådlös, mobil kommunikation.
Prof. Dr.-Ing. Jochen Schiller

6. …and the real rune stone
Freie Universität Berlin
Institut of Computer Science
Mobile Communications
2002
…and the real rune stone
Located in Jelling, Denmark,
erected by King Harald “Blåtand”
in memory of his parents.
The stone has three sides – one side
showing a picture of Christ.
Inscription:
"Harald king executes these sepulchral monuments after Gorm, his father and Thyra, his mother. The Harald who won the whole of Denmark and Norway and turned the Danes to Christianity."
This could be the “original” colors of the stone.
Inscription:
“auk tani karthi kristna” (and made the Danes Christians)
Btw: Blåtand means “of dark complexion”
(not having a blue tooth…)
Prof. Dr.-Ing. Jochen Schiller

7. Bluetooth Was Originally a Cable-Replacement Technology

8. In the Office … You arrive at the office … While in a meeting, …
When inspecting equipment, …

9. On the road … You arrive at the airport …
You enter the airport waiting lounge, …
You get on the rent-a-car bus, …

10. Bluetooth - overview Consortium: Ericsson, Intel, IBM, Nokia, Toshiba…
Scenarios:
connection of peripheral devices
loudspeaker, joystick, headset
support of ad-hoc networking
small devices, low-cost
bridging of networks
e.g., GSM via mobile phone - Bluetooth - laptop
Simple, cheap, replacement of IrDA, low range, lower data rates, low-power
Worldwide operation: 2.4 GHz
Available globally for unlicensed users
Resistance to jamming and selective frequency fading:
FHSS over 79 channels (of 1MHz each), 1600hops/s
Coexistence of multiple piconets: like CDMA
Links: synchronous connections and asynchronous connectionless
Interoperability: protocol stack supporting TCP/IP, OBEX, SDP
Range: 10 meters, can be extended to 100 meters
Documentation: over 1000 pages specification:

11. Bluetooth Universal radio interface for ad-hoc wireless connectivity
Interconnecting computer and peripherals, handheld devices, PDAs, cell phones – replacement of IrDA
Embedded in other devices, goal: 5€/device (already < 1€)
Short range (10 m), low power consumption, license-free 2.45 GHz ISM
Voice and data transmission, approx. 1 Mbit/s gross data rate
Supports open-ended list of applications
Data, audio, graphics, videos
One of the first modules (Ericsson).

12. Freie Universität Berlin Institut of Computer Science
Mobile Communications
2002
Characteristics
2.4 GHz ISM band, 79 (23) RF channels, 1 MHz carrier spacing
Channel 0: 2402 MHz … channel 78: 2480 MHz
G-FSK modulation, mW transmit power
FHSS and TDD
Frequency hopping with 1600 hops/s
Hopping sequence in a pseudo random fashion, determined by a master
Time division duplex for send/receive separation
Voice link – SCO (Synchronous Connection Oriented)
FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, circuit switched
Data link – ACL (Asynchronous ConnectionLess)
Asynchronous, fast acknowledge, point-to-multipoint, up to kbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switched
Topology
Overlapping piconets (stars) forming a scatternet
Prof. Dr.-Ing. Jochen Schiller

14. Bluetooth Application Areas
Data and voice access points
Real-time voice and data transmissions
Cable replacement
Eliminates need for numerous cable attachments for connection
Ad hoc networking
Device with Bluetooth radio can establish connection with another when in range
Developed in late 90s
V1.2 → 1Mbps
V2.0 → 3Mbps
V3.0 → 24Mbps

15. Bluetooth Architecture
Piconets and Scatternets
Piconet is the basic unit of networking
One master device and seven slaves
Slave can only communicate with its Master
Slave can be master of another piconet
This is called a scatternet
Piconet 1
Piconet 2
Slave
Master
Master
Scatternet

16. Piconets and Scatternets
Basic unit of Bluetooth networking
Master and one to seven slave devices
Master determines channel and phase
Scatternet
Device in one piconet may exist as master or slave in another piconet
Allows many devices to share same area
Makes efficient use of bandwidth

17. Freie Universität Berlin Institut of Computer Science
Mobile Communications
2002
Piconet
Collection of Bluetooth devices connected in an ad hoc fashion and synchronizes to a master node
One unit acts as master and the others as slaves for the lifetime of the piconet
All devices have the same network capabilities
The node establishing the piconet automatically becomes the master
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 (> 200 could be parked)
Parked device is an inactive device (can be reactivated in milliseconds)
Standby device do not participate in piconet
If a parked device wants to communicate and there are 7 active slaves, then one of the slaves has to switch to park mode P S S M P SB S P SB
M=Master
S=Slave
P=Parked
SB=Standby
Prof. Dr.-Ing. Jochen Schiller

18. Freie Universität Berlin Institut of Computer Science
Mobile Communications
2002
Forming a piconet
All devices in a piconet hop together
Master gives slaves its clock and device ID
Hopping pattern: determined by device ID (48 bit, unique worldwide)
Phase in hopping pattern determined by clock
Addressing
Active Member Address (AMA, 3 bit, 8 nodes) for all active nodes
Parked Member Address (PMA, 8 bit, 256) for parked nodes
SB devices do not need address   P  S   SB SB S    M P SB     SB SB SB S     SB P SB SB   SB SB
Prof. Dr.-Ing. Jochen Schiller

19. Freie Universität Berlin Institut of Computer Science
Mobile Communications
2002
Scatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
Devices can be slave in one piconet and master of another
Master-slave can switch roles
Communication between piconets
Devices jumping back and forth between the piconets
Overlapping piconets experience collisions
Piconets
(each with a
capacity of
720 kbit/s) P S S S P P M M SB S
M=Master
S=Slave
P=Parked
SB=Standby P SB SB S
Prof. Dr.-Ing. Jochen Schiller

20. Bluetooth Network Architecture

21. Piconets & ScatternetsM S S S S S S S
M/S S S S S S S S S

22. Bluetooth Standards
Details of various layers of Bluetooth protocol architecture
Bluetooth v1.1 ratified in 2002 as IEEE
Bluetooth v2.0 goes to up to 3Mbps – 2004
Bluetooth v2.1 adopted July 2007
Wibree, an ultra low power Bluetooth technology adopted as part of the Bluetooth specification – 2007.
Bluetooth v3.0 adopted April up to 24Mbps

23. Protocol Architecture
Bluetooth is a layered protocol architecture
Core protocols
Cable replacement and telephony control protocols
Adopted protocols (using profiles)
Radio
Baseband
Link manager protocol (LMP)
Logical link control and adaptation protocol (L2CAP)
Service discovery protocol (SDP)

24. Protocol Architecture
Cable replacement protocol
RFCOMM
Telephony control protocol
Telephony control specification – binary (TCS BIN)
Adopted protocols
PPP
TCP/UDP/IP
OBEX
WAP
Profiles
Specifications of how to support applications
Specify which parts of the total specification are mandatory, optional, or not applicable
No point having all functionality in all chips
Helps interoperability between vendors

25. Bluetooth protocol stack
Freie Universität Berlin
Institut of Computer Science
Mobile Communications
2002
Bluetooth protocol stack
audio apps.
NW apps.
vCal/vCard
telephony apps.
mgmnt. apps.
TCP/UDP
OBEX
AT modem
commands
TCS BIN
SDP
Control IP
BNEP
PPP
Audio
RFCOMM (serial line interface)
Logical Link Control and Adaptation Protocol (L2CAP)
Host
Controller
Interface
Link Manager
Baseband
Radio
AT: attention sequence
OBEX: object exchange
TCS BIN: telephony control protocol specification – binary
BNEP: Bluetooth network encapsulation protocol
SDP: service discovery protocol
RFCOMM: radio frequency comm.
Prof. Dr.-Ing. Jochen Schiller

26. Establishing a connection: BT – States
Standby: unconnected but awake
Inquiry: listening or wanting to connect
Page: setting up connections
Active: Connected or Transmitting

27. Inquiry Procedure Goal: aims at discovering other neighboring devices
Potential master or inquiring node identifies devices in range that wish to participate
Transmits ID packet with inquiry access code
Sends an inquiry message (packet with only the access code). This message is sent over a subset of all possible frequencies.
Listen for inquiry response
Occurs in Inquiry state
Device receives inquiry: to be discovered node:
Enters an inquiry_scan mode
When hearing the inquiry_message enter an inquiry_response mode: send a Frequency Hop Sync (FHS) packet with address and timing information
Moves to page scan state
After discovering the neighbors and collecting information on their address and clock, the inquiring node can start a page routine to setup a piconet

28. Page Procedure Goal: e.g., setup a piconet after an inquiry
Paging node (master):
uses devices address to calculate a page frequency-hopping sequence
Sends a page message (i.e., packet with only Device Access Code (DAC) of paged node)
Repeated until a response is received
When a response is received send a FHS message to allow the paged node to synchronize
Paged node (slave):
Listens on its hopping sequence
When receiving a page message, send a page_response and wait for the FHS of the pager
When receiving, slave moves to connection state

29. Slave Connection State Modes
Active – participates in piconet
Listens, transmits and receives packets
the device is uniquely identified by a 3bits AM_ADDR and is fully participating
Sniff – only listens on specified slots
Hold – does not support ACL packets
Reduced power status
May still participate in SCO exchanges
Park – does not participate on piconet
Still retained as part
of piconet
Release AM_ADDR,
but have PM_ADDR
Low Power
Park (PM_Address): still a member of piconet, loses AM_Address
Hold (AM_Address): not active but wants to keep AMA
Sniff (AM_Address): listens to parts of the signals for activity

30. Example (without security)
A Person in a hotel wants to access her over a BT enabled PDA. The device will automatically carry out the following steps
Inquiry
The device initiate an inquiry to find out access points (Masters) within its range
All nearby access points respond with their addresses
The device picks one out of the responding devices
Paging
The device will invoke paging procedure
It synchronizes with the access point in terms of clock, phase and frequency hop
Link establishment
The LMP will establish a link with the master
ACL link will be used ( )

31. Example (cont.) Service discovery L2CAP channel RFCOMM channel
The LMP will use SDP to discover what services are available at the master ( access to the host possible?)
Assume the service is available, else it would stop
Other available services will be presented to the user
L2CAP channel
With information obtained from SDP, an L2CAP channel will be created to the master
RFCOMM channel
An RFCOMM channel will be created over The L2CAP channel. This emulates serial port so applications can run without modifications
Network Protocols
The network protocols like TCP/IP can now send and receive data over the link

32. Wi-Fi v Bluetooth Wi-Fi Bluetooth LAN (local area) PAN (personal area)
Medium range
54Mbps (a/g)
Infrastructure
LAN extension
Simple connection
Secure authentication via WPA2 (considered safe)
Layer 1+2 only
Bluetooth
PAN (personal area)
Short range
1-3Mbs (v1+2)
Ad Hoc
Cable replacement
Complex connection
Secure authentication via SSP (known problems)
Integrates (profiles)

33. Bluetooth versions Bluetooth 1.1 Bluetooth 1.2
also IEEE Standard
initial stable commercial standard
Bluetooth 1.2
also IEEE Standard
eSCO (extended SCO): higher, variable bitrates, retransmission for SCO
AFH (adaptive frequency hopping) to avoid interference
Bluetooth EDR (2004, no more IEEE)
EDR (enhanced date rate) of 3.0 Mbit/s for ACL and eSCO
lower power consumption due to shorter duty cycle
Bluetooth EDR (2007)
better pairing support, e.g. using NFC
improved security
Bluetooth HS (2009)
Bluetooth EDR + IEEE a/g = 54 Mbit/s