1. A Bluetooth Overview by N.G.Alexiou
School of Computing & Mathematics Sciences
Liverpool John Moores University

2. A Bluetooth Overview What is Bluetooth? Bluetooth Development
Bluetooth Administrative Structure
Bluetooth Technology
Baseband Layer
Single & Multi-Slot Frame
Power Class Table
The Protocol Stack
Network Topology
Connection States
Forming a Piconet
Security in Bluetooth
Bluetooth Profile Structure
Bluetooth Vs Wireless Technologies
Bluetooth Competitors
Planned Future Work
References
A Bluetooth Overview

3. What is Bluetooth? (i)
Bluetooth is a Radio System (Radio Frequency Standard) which defines the concept of PANs (Personal Area Network)
Nominal Link Range up to 10m/ 0dBm (~100m with 20dBm)
Transmitting between 2.402Ghz – 2.480Ghz (79 channels / on a frequency hopping scheme)
Reaching Speeds up to 720Kbps
No line-of-sight Restrictions
High Security
A Bluetooth Overview

4. What is Bluetooth? (ii)
A Bluetooth Network can consist of 7 slave devices and 1 master device
Until Bluetooth no other global cellular technology for mobile users existed
Solve a simple problem, Replace cables used on mobile devices and their peripherals with radio frequency waves
Thus Bluetooth tries to emulate cost, security and capabilities of cable for mobile users
A Bluetooth Overview

5. Bluetooth Development
Bluetooth as a word derived from the 10th century king of Denmark (Harald Blatand)
As a research started in 1994 by Ericsson Mobile Communications with one goal  to relief cables carried by mobile phone users
In February 1998 Bluetooth SIG (Special Interest Group) founded, under the core promoters of
Ericsson, Intel, IBM, Toshiba and Nokia
In 1999 more core promoters added
Microsoft, Agere, 3Com and Motorola
Now exceeding 2500 members
A Bluetooth Overview

6. Bluetooth SIG Administrative Structure
Program Management Board
Regulatory
Legal Committee
Japan Regulations
Marketing
Bluetooth Qualification Review Board
Test & Interoperability
Architecture Review Board
Sub groups
RF Regulations
Aviation Regulations
Security Regulations
Management Services (ADMIN)
Bluetooth Technical Advisory Board
Bluetooth Qualification Admin
Bluetooth Qualification Body
Technical Working Groups
Expert Groups
Errata owners and review pool
Bluetooth SIG Administrative Structure
A Bluetooth Overview

7. Bluetooth Baseband Layer (i)
Bluetooth operates in ISM (Industrial Scientific Medical) band of 2.4GHz
Between 2.402GHz and 2.480GHz with the spacing of 1Mhz
Using a Frequency Hopping Spread Spectrum (FHSS) instead of Direct Sequence Spread Spectrum (DSSS)
The FHSS scheme provides 1600 hops / second and every hop is 625μs
Bluetooth packets can be multible slots, each packet can be composed of 1, 3 or 5 slots of 625μs each.
A Bluetooth Overview

8. Bluetooth Baseband Layer (ii)
Voice and Data links in Bluetooth RF can be divided into two types ACL & SCO (Also a third type which combines both – DV):
ACL (Asynchronous Connection-Less)
Made for non-critical data
Provides largest data rate of Kb/s in one direction
Asynchronous
Packet-switched
Constructed of 72 bit access code
54 bit packet header and 16 bit CRC
SCO (Synchronous Connection Oriented)
SCO functionality is for critical data and voice
SCO occurs after the ACL if needed
Circuit Switched
A master can support up to 3 SCO Links
Constructed of 72 bit access code
54 bit packet header
Uses slot reservation at fixed intervals
Data rate of 30b/s
Doesn’t have CRC (Cyclic Redundancy Code)
DV (Data Voice)
Has no flow Control or CRC (similar to SCO)
The Data part supports flow control and retransmission
A Bluetooth Overview

9. Bluetooth Single & Multi-Slot Frame
Master
Slave
625μs
F(1)
F(5) t
One Slot
F(2)+F(3)+F(4)
Multi slot
Bluetooth frame packets slots
A Bluetooth Overview

10. Bluetooth Power Class Table
Max Output Power
Expected Range
Range in
Free Space
Class 1
100mW
20dBm
42m
300m
Class 2
2.5mW
4dBm
16m
50m
Class 3
1mW
0dBm
10m
30m
Bluetooth Power Class Table
A Bluetooth Overview

11. Bluetooth SIG Complete Protocol Stack (i)
vCard/vCal
OBEX
WAE
WAP
UDP
TCP IP
PPP
AT-Commands
RFCOMM
TCS BIN
SDP
L2CAP
Host Controller Interface
LMP
BaseBand
Bluetooth Radio/RF
Audio
Complete Protocol Stack
A Bluetooth Overview

12. Bluetooth Protocol Stack (ii)
The Bluetooth protocol stack may differs from application to application, depending on the needs of the implementing Bluetooth Chip.
Bluetooth Radio/RF: Broadcasting in between 79 channels (2.402GHz-2.480GHz) on a FHSS (Frequency Hopping Spread Spectrum) scheme at 1600 hops/sec
Baseband Layer: Prepares the packets and arranges the communication channels (ACL-SCO)
LMP (Link Manager Protocol): Responsible for setting up the link between two Bluetooth radios (Security aspects and control issues on Baseband packet sizes) – Also LMP in charge of Bluetooth power modes and connection states.
L2CAP (Logical Link Control & Adaptation Protocol): L2CAP acts as a bridge between the upper layer protocols and the baseband layer. Adapts data and converts them into different packet sizes. Sometimes works in parallel with LMP, only for ACL links.
SDP (Service Discovery Protocol): Provides service discovery and is required in all usages models, by SDP we can interact-query other Bluetooth devices in the area about their status and their services.
A Bluetooth Overview

13. Bluetooth Protocol Stack (iii)
RFCOMM Protocol: Cable replacement protocol, emulates RS-232 control and signals, thus provides transport to data for upper layer services such as OBEX or PPP.
TCP (Telephony Control Protocol):
Telephony Control Binary: Defines the call control signalling for establishments of speech and data cells
Telephony Control AT Commands: Controls the modem and the mobile phone commands
(Adopted Protocols)
PPP (Peer-to-Peer Protocol): Mainly for peer-to-peer networking usage
TCP/UDP/IP (Transfer Control Protocol/User Datagram Protocol/Internet Protocol): Mainly for usage on internet
OBEX (IrOBEX): Emulates the HTTP (HyperText Transfer Protocol), in common word is the web browser of the Bluetooth.
WAP (Wireless Application Protocol): Supports the usage of wireless Computer applications developed for WAE (WAP Application Environment)
VCARD & VCalendar: Type of format which data supported, not a protocol or mechanism
A Bluetooth Overview

14. Bluetooth Network Topology
Bluetooth devices have the ability to work as a slave or a master in an ad hoc network. The types of network configurations for Bluetooth devices can be three.
Single point-to-point (Piconet): In this topology the network consists of one master and one slave device.
Multipoint (Piconet): Such a topology combines one master device and up to seven slave devices in an ad hoc network.
Scatternet: A Scatternet is a group of Piconets linked via a slave device in one Piconet which plays master role in other Piconet. M S
i) Piconet (Point-to-Point)
ii) Piconet (Multipoint)
Master/Slave
iii) Scatternet
A Bluetooth Overview

15. Bluetooth Connection States
There are four Connection states on Bluetooth Radio:
Active: Both master and slave participate actively on the channel by transmitting or receiving the packets (A,B,E,F,H)
Sniff: In this mode slave rather than listening on every slot for master's message for that slave, sniffs on specified time slots for its messages. Hence the slave can go to sleep in the free slots thus saving power (C)
Hold: In this mode, a device can temporarily not support ACL packets and go to low power sleep mode to make the channel available for things like paging, scanning etc (G)
Park: Slave stays synchronized but not participating in the Piconet, then the device is given a Parking Member Address (PMA) and it loses its Active Member Address (AMA) (D,I) E A G H C D I B F
Master
Bluetooth Connection States
A Bluetooth Overview

16. Bluetooth Forming a Piconet
Master
Inquiry
Inquiry Scan
Inquiry Response
Page
Page Scan
Slave Response
Master Response
Connection
Slave
Inquiry: Inquiry is used to find the identity of the Bluetooth devices in the close range.
Inquiry Scan: In this state, devices are listening for inquiries from other devices.
Inquiry Response: The slave responds with a packet that contains the slave's device access code, native clock and some other slave information.
Page: Master sends page messages by transmitting slave's device access code (DAC) in different hop channels.
Page Scan: The slave listens at a single hop frequency (derived from its page hopping sequence) in this scan window.
Slave Response: Slave responds to master's page message
Master Response: Master reaches this substate after it receives slave's response to its page message for it. 3 2 4 1 5 7 6
Forming a Piconet Procedures
A Bluetooth Overview

17. Bluetooth Security Three Security Modes Available in Bluetooth:
Security Mode 1- This is the most insecure security mode in which the Bluetooth device does not initiate any security procedure.
Security Mode 2- This mode enforces security after establishment of the link between the devices at the L2CAP level.
Security Mode 3- This mode enforces security controls such as authentication and encryption at the Baseband level itself, before the connection is set up.
And three Security Controls for restricting access to services:
Access to Services would need Authorization (Authorization always includes authentication). Only trusted devices would get automatic access.
Access to Services would need only Authentication. I.e. the remote device will need to get authenticated before being able to connect to the application
Access to Services would need Encryption. The link between the two devices must be encrypted before the application can be accessed.
A Bluetooth Overview

18. Bluetooth Profile Structure
Generic Access Profile
TCS-BIN-based Profiles
Cordless Telephony Profile
Intercom Profile
Service Discovery Profile
Serial Port Profile
Dial-up Networking Profile
Fax Profile
Headset Profile
LAN Access Profile
Generic Object Exchange Profile
File Transfer Profile
Object Push Profile
Synchronization Profile
Bluetooth Profile Structure
A Bluetooth Overview

19. Bluetooth Vs Wireless Technologies
HyperLAN2
DECT – DMAP (Depended
On the Antenna)
IEEE802.11
(Depended on the Antenna)
Gross Data Rate
Distance to Access Point
1 Mbps
100 Kbps
10 Mbps
100 Mbps
10 m
100 m
1000 m
10000 m
IrDA V1.0
(SIR)
IrDA V1.1
(FIR)
IrDA
(VFIR)
Bluetooth
HomeRF1.2
HomeRF2.0
HomeRF2.1
IEEE802.11b
HyperLan
GSM / WAP
GPRS
UMTS (FDD)
UMTS (TDD)
IEEE802.11a
Wireless Technologies Graph – Distance Vs Data Rate
A Bluetooth Overview

20. Bluetooth WLANs Competitors
HomeRF
802.11b
HyperLAN
802.11a
HyperLAN2
Frequency Band
2.4GHz
2.4GHZ
5GHz
Technology
Frequency Hopping Spread Spectrum
Direct Sequence Spread Spectrum
Guassian Minimum Shift Keying
Orthogonal Frequency Division Multiplexing
Performance
720Kbps
1.6Mbps
11Mbps
23Mbps
~50Mbps
Range m
50 m
~ m
~ m
~ m
Power
Very Low
Medium
Medium/High
Relative Cost
Low/Very Low
Medium/Low
High
Target Applications
Cable Replacement, Wireless Data, Wireless Voice, PANs
Wireless Data, Wireless Voice
Wireless Data
Key Features
Very Low Power,
Low Cost,
Voice & Data
Voice & Data,
Moderate Cost
Good Performance
High Performance
Promoters
2500+
<50
~100
Regional Support
Global US
US/Asia
Europe
Comparison Table of the most popular WLANs Technologies
A Bluetooth Overview

21. Planned Future Work Planned Future work will concentrate on:
Analyzing and studying deeper the capabilities on Bluetooth Technology Vs the Rest Wireless Family
Verifying that currently developed Bluetooth technology covers all the needs & necessities required for such a technology (If any further development could be done in major areas such as security or protocols)
Visualizing the procedures followed by a Bluetooth Master device to create a Piconet, in order to specify how Bluetooth interacts in Real-Time Environments
Creating a middleware platform able to interact “openly” in a Master Bluetooth device for monitoring communication issues between the Master Device and Slave Devices in a Bluetooth Piconet
A Bluetooth Overview

22. References
Specification of Bluetooth System, Profiles Version 1.1, February , Specification Volume 2, Bluetooth SIG (
Bluetooth Architecture Overview, James Kardach, Mobile Computing Group, Intel Corporation
Direct Sequence vs. Frequency Hopping, Wave Wireless Networking, 2000,
Bluetooth Security Architecture, Version 1.0, 15 July 1999, Thomas Muller, (
How Bluetooth’s unusual operating characteristics impact test decisions, Teit Poulsen, September , PRIMEDIA Business Magazines & Media
Bluetooth Protocol Architecture, Version 1.0, August 25th 1999, Riku Mettala, (
Bluetooth Security, , Juha T. Vainio, Department of Computer Science and Engineering Helsinki University of Technology
A Bluetooth Overview