1. L6: WPAN-- Bluetooth Characteristics Piconet and Scatternet
MAC mechanism
Connection Management

2. Wireless PAN WPAN WPAN vs. WLAN Wireless Personal Area Network
smaller coverage area (~10 m)
lower data rate (~1 Mbps)
ad hoc only topology
lower power consumption (~1mW)

3. Prof Weijia Jia, Bluetooth
Short range (10 m)
Low power consumption
2.4 GHz (Unlicensed ISM Band)
Advantage: worldwide availability
Disadvantage: interfere with IEEE b products
Voice and data transmission, totally 1 Mbps
Low cost
less than US$5 for a Bluetooth chip

4. Prof Weijia Jia, Bluetooth
Universal radio interface for ad-hoc wireless connectivity
Voice and data transmission, approx. 1 Mbit/s gross data rate
One of the first modules (Ericsson).

5. Application Scenarios
Prof Weijia Jia, Bluetooth
Application Scenarios
Cable Replacement
Ad Hoc Personal Network (e.g. connect multiple users in a conference room)
Integrated Access Point: connect wireless devices to both voice and data backbone infrastructure.

6. History 1994 Initial study started at Ericsson, Sweden. 1998
Ericsson, Nokia, IBM, Toshiba and Intel formed a Special Interest Group (SIG) to develop a standard.
1999
First specification was released and accepted as the IEEE WPAN standard.
Today
Over 10,000 companies joined the Bluetooth SIG.

7. Why is it called “Bluetooth”?
Harald Blaatand
translated in English means “Bluetooth”
A.D
a king of Denmark and Norway
Brought Christianity to Scandinavians to harmonize their beliefs with the rest of Europe.
symbolize the need for harmony among manufacturers of WPANs around the world.

8. Prof Weijia Jia, Bluetooth
History and hi-tech…
1999:
Ericsson mobile communications.

9. …and the real rune stone
Prof Weijia Jia, Bluetooth
…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…)

10. Prof Weijia Jia, Bluetooth
Characteristics
2.4 GHz ISM (industry-scientific-medical) band, 79 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

11. Prof Weijia Jia, Bluetooth
Piconet
Before a connection is created, a device is in “standby” mode, periodically listen for messages every 1.28 sec.
Devices are connected in an ad hoc fashion, called piconet.
One unit acts as master and the others as slaves for the lifetime of the piconet. Each piconet has 1 master and up to 7 slaves.
Master determines hopping pattern, slaves have to synchronize. P S S M P SB S P SB
M = Master
S = Slave
P = Parked
SB = Standby

12. Prof Weijia Jia, Bluetooth
Piconet (con’t)
Each piconet has a unique hopping pattern
Participation in a piconet = synchronization to hopping sequence
Other devices within the piconet will be considered “parked”.
Parked devices, as well as the slaves, are synchronized to the master. P S S M P SB S P SB
M = Master
S = Slave
P = Parked
SB = Standby

13. Prof Weijia Jia, Bluetooth
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)
Parked Member Address (PMA, 8 bit)    P  S SB  SB  S   SB   M P SB SB    SB  S   SB SB  P  SB SB SB

14. Prof Weijia Jia, Bluetooth
Scatternet
Linking of multiple co-located piconets through the sharing of common master or slave devices
A device can be slave in one piconet and master of another
No device can be master of two piconets
Piconets
(each with a
capacity of
< 1 Mbit/s) P S S S M M P P SB
M=Master
S=Slave
P=Parked
SB=Standby S P SB SB S

15. Bluetooth protocol stack
Prof Weijia Jia, Bluetooth
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.

16. Bluetooth protocols
"Bluetooth is defined as a layer protocol architecture consisting of core protocols, cable replacement protocols, telephony control protocols, and adopted protocols”.
Mandatory protocols for all Bluetooth stacks are: LMP, L2CAP and SDP. Additionally, these protocols are almost universally supported: HCI and RFCOMM.

17. Core Protocols Radio Baseband Link Manager Protocol (LMP)
Physical layer aspects, e.g. frequency hopping
Baseband
Link control at bit and packet level, e.g. coding, encryption
Provides two types of physical links, SCO and ACL, to be described later
Link Manager Protocol (LMP)
Link setup and ongoing link management. Used for control of the radio link between two devices. Implemented on the controller.
Logical Link Control and Adaptation Protocol (L2CAP – see next)
Provide services to upper layer protocols (e.g. packet segmentation and assembly).
Service Discovery Protocol (SDP)
Discover available services and connects two or more devices to support a service such as faxing, printing, etc.

18. L2CAP
Multiplex multiple logical connections between two devices using different higher level protocols. Provides segmentation and reassembly of on-air packets.
Basic mode,
L2CAP provides payload up to 64kB, with 672 bytes as the default MTU, and 48 bytes as the minimum mandatory supported MTU.
Retransmission & Flow Control modes
L2CAP can be configured for reliable or isochronous data per channel by performing retransmissions and CRC checks.
Reliability in any of these modes is optionally

19. Service Discovery Protocol (SDP)
Service Discovery Protocol (SDP) allows a device to discover services supported by other devices, and their associated parameters.
E.g. when connecting a mobile phone to a Bluetooth headset, SDP will be used for determining which Bluetooth profiles are supported by the headset (Headset Profile, Hands Free Profile, Advanced Audio Distribution Profile (A2DP) etc.) and the protocol multiplexer settings needed to connect to each of them. Each service is identified by a Universally Unique Identifier (UUID), with official services (Bluetooth profiles) assigned a short form UUID (16 bits rather than the full 128)

20. Bluetooth – other protocols
HCI (Host/Controller Interface)
Standardised communication between the host stack (e.g., a PC or mobile phone OS) and the controller (the Bluetooth IC). This standard allows the host stack or controller IC to be swapped with minimal adaptation.
There are several HCI transport layer standards, each using a different hardware interface to transfer the same command, event and data packets. The most commonly used are USB (in PCs) and UART (in mobile phones and PDAs).
In Bluetooth devices with simple functionality (e.g., headsets) the host stack and controller can be implemented on the same microprocessor. In this case the HCI is optional, although often implemented as an internal software interface.

21. Bluetooth – other protocols
RFCOMM (Serial Port Emulation) for Radio frequency communications
Provides for binary data transport and emulates EIA-232 (formerly RS-232) control signals over the Bluetooth baseband layer.
Provides a simple reliable data stream to the user, similar to TCP.
Used directly by many telephony related profiles as a carrier for AT commands, as well as being a transport layer for OBEX (OBject Exchange) over Bluetooth.
Widespread support and publicly available API on most operating systems.

22. Bluetooth protocol -- HCI (Host/Controller Interface)
BNEP (Bluetooth Network Encapsulation Protocol)
BNEP is used for transferring another protocol stack's data via an L2CAP channel. Its main purpose is the transmission of IP packets in the Personal Area Networking Profile. BNEP performs a similar function to SNAP in Wireless LAN.
AVCTP (Audio/Video Control Transport Protocol)
Used by the remote control profile to transfer AV/C commands over an L2CAP channel. The music control buttons on a stereo headset use this protocol to control the music player.
AVDTP (Audio/Video Distribution Transport Protocol)
Used by the advanced audio distribution profile to stream music to stereo headsets over an L2CAP channel. Intended to be used by video distribution profile.

23. Other Bluetooth protocols -- Telephony control protocol
Telephony control protocol-binary (TCS BIN) is the bit-oriented protocol that defines the call control signaling for the establishment of voice and data calls between Bluetooth devices. Additionally, "TCS BIN defines mobility management procedures for handling groups of Bluetooth TCS devices."
TCS-BIN is only used by the cordless telephony profile, which failed to attract implementers. As such it is only of historical interest.

24. Other Bluetooth protocols : Adopted protocol
Adopted protocols are defined by other standards-making organizations and incorporated into Bluetooth’s protocol stack, allowing Bluetooth to create protocols only when necessary. The adopted protocols include:
Point-to-Point Protocol (PPP)
Internet standard protocol for transporting IP datagrams over a point-to-point link.
TCP/IP/UDP
Foundation Protocols for TCP/IP protocol suite
Object Exchange Protocol (OBEX)
Session-layer protocol for the exchange of objects, providing a model for object and operation representation
Wireless Application Environment/Wireless Application Protocol (WAE/WAP)
WAE specifies an application framework for wireless devices and WAP is an open standard to provide mobile users access to telephony and information services.

25. Three Classes of Transmitters
Output power: 1 mW – 100 mW
Range: up to 100 m
Power control is mandatory
Class 2
Output power: 0.25 mW – 2.4 mW
Range: 10 m
Power control is optional
Class 3
Output power: 1 mW
Range: 0.1 – 10 m

26. MAC mechanism FH-CDMA/TDD Polling Frequency Hopping CDMA
Time Division Duplex
Polling
Master polls the slaves for transmission
No collision/interference within a piconet

27. Frequency Hopping Totally, 79 frequencies for hopping
Each of bandwidth 1 MHz
k MHz, k = 0, 1, ..., 78
ALL devices on a piconet follow the SAME frequency hopping sequence.
1600 hops per second
Therefore, each frequency is occupied for a duration of 625 sec., called a slot.

28. Prof Weijia Jia, Bluetooth
Hopping Sequence
Every Bluetooth device has
a unique device ID (48 bits Bluetooth address)
a clock
Master gives its device ID and clock to its slaves
Hopping pattern: determined by device ID
Timing in hopping pattern: determined by clock
All slaves synchronizes to the master

29. Polling for Transmission
The MASTER polls the SLAVES according to certain rules
- e.g. round robin P S S M P
Time Division Duplex (TDD)
When a master is transmitting, the slave is receiving and cannot transmit. SB S P SB

30. Prof Weijia Jia, Bluetooth
Baseband link types
Polling-based TDD packet transmission
625µs slots, master polls slaves
SCO (Synchronous Connection Oriented) – Voice
Periodic single slot packet assignment, 64 kbit/s full-duplex, point-to-point
ACL (Asynchronous Connectionless) – Data
Variable packet size (1,3,5 slots), asymmetric bandwidth, point-to-multipoint

31. Alternate Transmission
Master transmits on even numbered slots
Slave transmits on odd numbered slots
A slave can transmit only if the master has just transmitted to this slave
f(k): the frequency used in slot k according to the hopping sequence.

32. Frequency selection during data transmissionfk
fk+1
fk+2
fk+3
fk+4
fk+5
fk+6 M S M S M S M t fk
fk+3
fk+4
fk+5
fk+6 M S M S M t fk
fk+1
fk+6 M S M t

33. Baseband Packet Format
Prof Weijia Jia, Bluetooth
Baseband Packet Format
Synchronization, paging and inquiry
Identify packet type and carry control information
Carry information bits
The header field has 18 bits that are repeated 3 times for error correction. 72 54
0-2745
bits
access code
packet header
payload 4 64 4 3 4 1 1 1 8
bits
preamble
sync.
(trailer)
AM address
type
flow
ARQN
SEQN
HEC
Active Member Address:
Up to 7 active slaves;
000 reserved for broadcast
Parity Check for the header
Packet Types
Status Reports

34. Baseband data rates/rules
Prof Weijia Jia, Bluetooth
Baseband data rates/rules
Payload User Symmetric Asymmetric Max. Rate
Header Payload max. Rate [kbit/s]
Type [byte] [byte] FEC CRC [kbit/s] Forward Reverse
DM /3 yes
DH no yes
DM /3 yes
DH no yes
DM /3 yes
DH no yes
AUX no no
HV1 na 10 1/3 no 64.0
HV2 na 20 2/3 no 64.0
HV3 na 30 no no 64.0
DV 1 D 10+(0-9) D 2/3 D yes D D
ACL
1 slot
3 slot
5 slot
SCO
Data Medium/High rate, High-quality Voice, Data and Voice

35. Physical Links
Two types of links can be established between a master and a slave.
Synchronous Connection Oriented (SCO)
For delay-sensitive traffic, e.g. voice
Slots are reserved at regular intervals
Basic unit of reservation is two consecutive slots (one in each direction).
Asynchronous ConnectionLess (ACL)
For best-effort traffic, e.g. data
Use variable packet size (1,3,5 slots) to support asymmetric bandwidth

36. Packet Types Control packets SCO ACL Integrated Four different types
Three different types
64 kbps voice with different error protection
ACL
Six different types
Different error protection and different data rates
Integrated
Carries both voice and data

37. SCO payload types payload (30) HV1 audio (10) FEC (20) HV2 audio (20)DV
audio (10)
header (1)
payload (0-9)
2/3 FEC
CRC (2)
(bytes)

38. SCO Packet Frame Formats
No. of bits
High-quality Voice
Three different types
Forward Error Correction

39. Prof Weijia Jia, Bluetooth
Example
SCO
ACL
SCO
ACL
SCO
ACL
SCO
ACL
MASTER f0 f4 f6 f8
f12
f14
f18
f20
SLAVE 1 f1 f7 f9
f13
f19
SLAVE 2 f5
f17
f21
A multislot packet is transmitted using the same frequency until the entire packet has been sent.
In the next slot after the multislot packet, the frequency is chosen according to the original hopping sequence.
Therefore, two or four hop frequencies have been skipped.

40. Prof Weijia Jia, Bluetooth
Robustness
Slow frequency hopping with hopping patterns determined by a master
Protection from interference on certain frequencies
Separation from other piconets (FH-CDMA)
Retransmission
ACL only, very fast
Forward Error Correction
SCO and ACL
Error in payload
(not transmitted!)
NAK
ACK
MASTER A C C F H
SLAVE 1 B D E
SLAVE 2 G G

41. ACL Packet Frame Formats (in bit)
Data Medium
Data High
Six different types

42. ACL Payload types (in byte)
header (1/2)
payload (0-339)
CRC (2)
DM1
header (1)
payload (0-17)
2/3 FEC
CRC (2)
DH1
header (1)
payload (0-27)
CRC (2)
(bytes)
DM3
header (2)
payload (0-121)
2/3 FEC
CRC (2)
DH3
header (2)
payload (0-183)
CRC (2)
DM5
header (2)
payload (0-224)
2/3 FEC
CRC (2)
DH5
header (2)
payload (0-339)
CRC (2)
AUX1
header (1)
payload (0-29)

43. Data Rate DH1 – data high rate – 1 slot/pkt + 1 byte header
DM1 – data medium rate – 1 slot/pkt + 1 byte header
DH3 – data high rate – 3 slot/pkt + 2 byte header
DM3 – data medium rate – 3 slot/pkt + 2 byte header
DH5 – data high rate – 5 slot/pkt+ 2 byte header
DM5 – data medium rate – 5 slot/pkt + 2 byte header

44. Example: Data Rate of DH1
Suppose that there is 1 master and 1 slave. What is the data rate of DH1 packets in each direction?
Solution:
216 bits per slot
800 slots per second (every other slot) in each direction
Data rate = 216 (bits/slot) × 800 (slots/sec)
= Kbps

45. ACL Packet Types and Associated Data Rates
Symmetric
Asymmetric
DM1
108.8
DH1
172.8
DM3
258.0
387.2
54.4
DH3
384.0
576.0
86.4
DM5
286.7
477.8
36.3
DH5
433.9
723.2
57.6

46. How to calculate the rate?
DM3 – 3 slot/pkt + 2 byte header; Symmetric – Each direction use 3 slot, thus, 800/3(slots/s)*968 bits = bits/s
DH5 – Symmetric – Each direction use 5 slot, thus, 800/5(slots/s)*2712 bits = bits/s
DM3 – Asymmetric – One direction use 3 slot and another direction uses 1 slot (ack), thus, 1600/4(slots/s)*968 bits = bits/s

47. Connection Management

48. States of a Bluetooth device
Prof Weijia Jia, Bluetooth
States of a Bluetooth device
standby
Unconnected
inquiry
page
Connecting
transmit
AMA
connected
AMA
Active
park
PMA
hold
AMA
sniff
AMA
Power saving
Standby: do nothing
Inquire: search for other devices
Page: connect to a specific device
Connected: participate in a piconet
Park: release AMA, get PMA
Sniff: listen periodically, not each slot
Hold: stop ACLs, SCO still possible, possibly participate in another piconet

49. Establishing a Connection
Standby
Devices not connected in a piconet are in standby mode
Inquiry
A device sends an inquiry message to locate other devices within communication range.
That device becomes Master
Timing and ID of other devices are sent to the Master
Those devices become Slaves
Page
The Master sends its timing and ID to the slaves using a page message.
A piconet is established and communication session takes place

50. Power Saving Modes Hold Sniff Park No data is transmitted
The device may connect to another piconet
Sniff
The device listens to the piconet at reduced intervals
Park
The device gives up its Active Member address but remains synchronized to the piconet
It does not participate in the traffic but check on broadcast messages.

51. Summary: IEEE 802.15-1.0 – Bluetooth
Prof Weijia Jia, Bluetooth
Summary: IEEE – Bluetooth
Data rate
Synchronous, connection-oriented: 64 kbit/s
Asynchronous, connectionless
433.9 kbit/s symmetric
723.2 / 57.6 kbit/s asymmetric
Transmission range
POS (Personal Operating Space) up to 10 m
with special transceivers up to 100 m
Frequency
Free 2.4 GHz ISM-band
Security
Challenge/response (SAFER+), hopping sequence
Cost
50€ adapter, drop to 5€ if integrated
Availability
Integrated into some products, several vendors
Connection set-up time
Depends on power-mode
Max. 2.56s, avg. 0.64s
Quality of Service
Guarantees, ARQ/FEC
Manageability
Public/private keys needed, key management not specified, simple system integration
Special Advantages/Disadvantages
Advantage: already integrated into several products, available worldwide, free ISM-band, several vendors, simple system, simple ad-hoc networking, peer to peer, scatternets
Disadvantage: interference on ISM-band, limited range, max. 8 devices/network&master, high set-up latency

52. Prof Weijia Jia, Bluetooth
Many errors found in the 1.0B specifications were fixed.
Added support for non-encrypted channels.
Received Signal Strength Indicator (RSSI).

53. WPAN: IEEE 802.15 – future developments 1
Prof Weijia Jia, Bluetooth
WPAN: IEEE – future developments 1
: Coexistance
Coexistence of Wireless Personal Area Networks (802.15) and Wireless Local Area Networks (802.11), quantify the mutual interference
: High-Rate
Standard for high-rate (20Mbit/s or greater) WPANs, while still low-power/low-cost
Data Rates: 11, 22, 33, 44, 55 Mbit/s
Quality of Service isochronous protocol
Ad hoc peer-to-peer networking
Security
Low power consumption
Low cost
Designed to meet the demanding requirements of portable consumer imaging and multimedia applications

54. Prof Weijia Jia, Bluetooth
Backward compatible with 1.1
Faster Connection and Discovery
Adaptive frequency-hopping spread spectrum (AFH.
Higher transmission speeds in practice, up to 721 kbit/s, than in 1.1.
Extended Synchronous Connections (eSCO) improve voice quality of audio links.
Introduced Flow Control and Retransmission Modes for L2CAP.

55. Prof Weijia Jia, Bluetooth
Three times the transmission speed ( Mbit/s) in some cases.
Reduced complexity of multiple simultaneous connections due to additional bandwidth.
Lower power consumption through a reduced duty cycle.

56. Prof Weijia Jia, Bluetooth
Supports theoretical data transfer speeds of up to 24 Mbit/s.
AMP -- (Alternate MAC/PHY), addition of as a high speed transport. Two technologies had been anticipated for AMP:

57. Prof Weijia Jia, Bluetooth
Bluetooth V4.0Future
4.0: low energy protocols
Future
Broadcast channel: Enables Bluetooth information points, pulling information from the information points, and not based around the object push model that is used in a limited way today.
Topology management: Enables the automatic configuration of the piconet topologies especially in scatternet situations that are becoming more common today. This should all be invisible to users of the technology, while also making the technology "just work."
QoS improvements: Enable audio and video data to be transmitted at a higher quality, especially when best effort traffic is being transmitted in the same piconet.

58. WPAN: IEEE 802.15 – future developments 2
Prof Weijia Jia, Bluetooth
WPAN: IEEE – future developments 2
: Low-Rate, Very Low-Power
Low data rate solution with multi-month to multi-year battery life and very low complexity
Potential applications are sensors, interactive toys, smart badges, remote controls, and home automation
Data rates of kbit/s, latency down to 15 ms
Master-Slave or Peer-to-Peer operation
Support for critical latency devices, such as joysticks
CSMA/CA channel access (data centric), slotted (beacon) or unslotted
Automatic network establishment by the PAN coordinator
Dynamic device addressing, flexible addressing format
Fully handshaked protocol for transfer reliability
Power management to ensure low power consumption
16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US ISM band and one channel in the European 868 MHz band

59. References
Ch J. Schiller, Mobile communications, Addison-Wesley, 2004.
K. Pahlavan and P. Krishnamurthy, Principles of wireless networks: a unified approach, Prentice Hall, 2002.