WPANs (Bluetooth)

1
(No Transcript)
2
WPAN INTRODUCTION

• A WPAN (Wireless PAN) is a short-distance
  wireless network specifically designed to support
  portable and mobile computing devices such as
  PCs, PDAs, wireless printers and storage devices,
  cell phones, pagers, set-top boxes, and a variety
  of consumer electronics equipment.
• Bluetooth is an example of a wireless PAN that
  allows devices within close proximity to join
  together in ad hoc wireless networks in order to
  exchange information.
• Many cell phones have two radio interfaces-one
  for the cellular network and one for PAN
  connections.

3
WPAN

• WPANs such as Bluetooth provide the bandwidth
• and convenience to make data exchange practical
  
• for mobile devices such as palm computers.
• Bluetooth overcomes many of the complications
• of other mobile data systems such as cellular
• packet data systems...
• The reach of a PAN is typically a few meters.

4
WPAN

• A Bluetooth PAN is also called a piconet, and is
  composed of up to 8 active devices in a
  master-slave relationship (up to 255 devices can
  be connected in 'parked' mode).
• The first Bluetooth device in the piconet is the
  master, and all other devices are slaves that
  communicate with the master.
• A piconet typically has a range of 10 meters,
  although ranges of up to 100 meters can be
  reached under ideal circumstances.

5
WPAN

• A wireless PAN consists of a dynamic group of
  less than 255 devices that communicate within
  about a 33-foot range.
• Unlike with wireless LANs, only devices within
  this limited area typically participate in the
  network, and no online connection with external
  devices is defined.
• One device is selected to assume the role of the
  controller during wireless PAN initialization,
  and this controller device mediates communication
  within the WPAN.

6
WPAN

• The controller broadcasts a beacon that lets all
  devices synchronize with each other and allocates
  time slots for the devices.
• Each device attempts to join the wireless PAN by
  requesting a time slot from the controller.
• The controller authenticates the devices and
  assigns time slots for each device to transmit
  data.
• The data may be sent to the entire wireless PAN
  using the wireless PAN destination address, or it
  may be directed to a particular device.

7
WPAN

• The 802.15 working group is defining different
  versions for devices that have different
  requirements.
• 802.15.3 focuses on high-bandwidth (about 55M
  bit/sec), low-power MAC and physical layers,
  while 802.15.4 deals with low-bandwidth (about
  250K bit/sec), extra-low power MAC and physical
  layers.

8
WPAN History

• WPAN smaller area of coverage, ad hoc only
  topology, plug and play architecture, support of
  voice and data devices, and low-power
  consumption.
• BodyLAN (DARPA, mid-1990s) inexpensive WPAN with
  modest bandwidth that could connect personal
  devices within a range of about 5 feet.
• 802.11 project initiated a WPAN group in 1997.
• In March 1998, the HomeRF group was formed
• In May 1998, a Bluetooth special group was formed
• In March 1999, 802.15 was approved as a separate
  group to handle WPAN

9
IEEE 802.15 WPAN

• Development of standards for short distance
  wireless networks used for networking of portable
  ad mobile computing devices.
• The original functional requirement was published
  in January 22, 1998, and specified devices with
• Power management low current consumption
• Range 0 - 10 meters
• Speed 19.2 - 100 kbps
• Small size .5 cubic inches without antenna
• Low cost relative to target device
• Should allow overlap of multiple networks in the
  same area
• Networking support for a minimum of 16 devices

10
IEEE 802.15 WPAN

• The initial activities in the WPAN group included
  HomeRF and Bluetooth group.
• HomeRF currently has its own website HomeRFweb
• IEEE 802.15 WPAN has four task groups
• Task group 1 based on Bluetooth. Defines PHY and
  MAC for wireless connectivity with fixed,
  portable, and moving devices within or entering a
  personal operating space.
• Task group 2 focused on coexistence of WPAN and
  802.11 WLANs.
• Task group 3 PHY and MAC layers for high-rate
  WPANs (higher than 20 Mbps)
• Task group 4 ultra-low complexity, ultra-low
  power consuming, ultra-low cost PHY and MAC layer
  for data rates of up to 200 kbps.

11
Bluetooth

• Idea
• 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 (2002
  50/USB Bluetooth)
• Short range (10 m), low power consumption,
  license-free 2.45 GHz ISM
• Voice and data transmission, approx. 1 Mbit/s
  gross data rate

12
Bluetooth
One of the first modules (Ericsson).
13
History and hi-tech
14
Bluetooth

• History
• 1994 Ericsson (Mattison/Haartsen), MC-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,
  www.bluetooth.org
• 1999 erection of a rune stone at Ericsson/Lund
• 2001 first consumer products for mass market,
  spec. version 1.1 released
• Special Interest Group
• Original founding members Ericsson, Intel, IBM,
  Nokia, Toshiba
• Added promoters 3Com, Agere (was Lucent),
  Microsoft, Motorola
• gt 2500 members
• Common specification and certification of products

15
and the real 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)
16
Characteristics

• 2.4 GHz ISM band, 79 RF channels, 1 MHz carrier
  spacing
• Channel 0 2402 MHz channel 78 2480 MHz
• G-FSK modulation, 1-100 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 433.9 kbit/s symmetric
  or 723.2/57.6 kbit/s asymmetric, packet switched
• Topology
• Overlapping piconets (stars) forming a scatternet

17
Bluetooth Protocol Stack
18
Frequency Selection During Data Transmission
(TDMA/TDD)
symmetric
asymmetric
asymmetric
19
Overall Frame Format of Bluetooth Packets

• The 48 bit address unique to every Bluetooth
  device is used as the seed to derive the sequence
  for hopping frequencies of the devices.
• Four types of access codes
• Type 1 identifies a M terminal and its piconet
  address
• Type 2 identifies a S identity used to page a
  specific S.
• Type 3 Fixed access code reserved for the
  inquiry process (will be explained)
• Type 4 dedicated access code reserved to
  identify specific set of devices such as fax
  machines, printers, or cell phones.
• Header 18 bits repeated 3 times with a 1/3 FEC
  code

bits
20
Overall Frame Format of Bluetooth Packets

• S-address allows addressing the 7 possible S
  terminals in a piconet
• The 4-bit packet type allows for 16 choices of
  different grade voice systems
• 6 of this payload types are asynchronous
  connectionless (ACL), primarily used for packet
  data communication
• 3 of the payload types are synchronous connection
  oriented (SCO), primarily used for voice
  communications
• 1 a integrated voice (SCO) and data (ACL) packet
• 4 are control packets common for both SCO and ACL
  links

bits
21
Control Packets

• Four types
• ID occupies half of a slot, and it carries the
  access code with no data or even a packet type
  code
• NULL used for ACK signaling, and there is no ACK
  for it
• POLL similar to the NULL, but is has an ACK
• NULL and POLL have the access code and the
  header, and so they have packet type codes and
  status report bits
• M terminals use the POLL packet to find the S
  terminals in their coverage area.
• FHS (Frequency Hop Synchronization) carries all
  the information necessary to synchronize two
  devices in terms of access code and hopping
  timing. This packet is used in the inquiry and
  paging process explained later.

22
Polling-based Transmission

• 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

MASTER
SLAVE 1
SLAVE 2
23
Connection Management

• In the beginning of the formation of a piconet,
  all devices are in SB mode, then one of the
  devices starts with an inquiry and becomes the
  M terminal.
• During the inquiry process, M registers all the
  SB terminals that then become S terminals.
  After the inquiry process, identification and
  timing of all S terminals is sent to M using
  FHS packets.
• The M terminal starts a connection with a PAGE
  message including its timing and ID to the S
  terminal.
• When the connection is established, the
  communication takes place, and at the end, the
  terminal can be sent back to SB, Hold, park or
  Sniff states.

24
Connection Management

• Hold, Park and Sniff are power-saving modes.
• The Hold mode is used when connecting several
  piconets or managing a low-power device.
• In the Hold mode, data transfer restarts as soon
  as the unit is out of this mode.
• In the Sniff mode, a slave listens to the piconet
  at reduced and programmable intervals according
  to the applications needs.
• In the Park mode a device gives up its MAC
  address but remains synchronized with the
  piconet.
• A Parked device does not participate in the
  traffic but occasionally listens to the traffic
  of M to resynchronize and check on broadcast
  messages.

25
Interference Between Bluetooth and 802.11

• The WLAN industry specified three levels of
  overlapping
• Interference multiple wireless networks are said
  to interfere with one another if colocation
  causes significant performance degradation
• Coexistence multiple wireless networks are said
  to coexist if they can be colocated without
  significant impact on performance. It provides
  for the ability of one system to perform a task
  in a shared frequency band with other systems
  that may or may not be using the same rules for
  operation
• Interoperation provides for an environment with
  multiple wireless systems to perform a given task
  using a single set of rules

26
Piconet

• Collection of devices connected in an ad hoc
  fashion
• One unit acts as master and the others as slaves
  for the lifetime of the piconet
• 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 (gt 200 could be parked)

P
S
S
M
P
SB
S
P
SB
PParked SBStandby
MMaster SSlave
27
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)

28
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
• Communication between piconets
• Devices jumping back and forth between the
  piconets

MMaster SSlave PParked SBStandby
29
WPAN IEEE 802.15-1 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/networkmaster, high set-up
  latency

30
WPAN IEEE 802.15 future developments 1

• 802.15-2 Coexistence
• Coexistence of Wireless Personal Area Networks
  (802.15) and Wireless Local Area Networks
  (802.11), quantify the mutual interference
• 802.15-3 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

31
WPAN IEEE 802.15 future developments 2

• 802.15-4 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 20-250 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

32
Bluetooth
Why not use Wireless LANs? - power - cost

• A cable replacement technology
• 1 Mb/s symbol rate
• Range 10 meters
• Single chip radio baseband
• at low power low price point (5)

33
IEEE 802.11 Classical WLANs

• Replacement for Ethernet
• Supported data rates
• 11, 5.5, 2, 1 Mbps and recently up to 20Mbps _at_
  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

34
Emerging Landscape
IEEE 802.11
Bluetooth
Cordless headset
LAN AP

• Which option is technically superior ?
• What market forces are at play ?
• What can be said about the future ?

35
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 (gt1,500 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

36
New Applications
37
Synchronization

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

38
Cordless Headset
Cordless headset

• User benefits
• Multiple device access
• Cordless phone benefits
• Hands free operation

39
Usage Scenarios Examples

• Data Access Points
• Synchronization
• Headset
• Conference Table
• Cordless Computer
• Business Card Exchange
• Instant Postcard
• Computer Speakerphone

40
Bluetooth Specifications
41
Bluetooth Specifications
Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF

• A hardware/software/protocol description
• An application framework

42
Interoperability Profiles
Applications

• 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

Protocols
Profiles
43
Bluetooth Profiles (in version 1.2 release)

• Generic Access
• Service Discovery
• Cordless Telephone
• Intercom
• Serial Port
• Headset
• Dial-up Networking
• Fax
• LAN Access
• Generic Object Exchange
• Object Push
• File Transfer
• Synchronization

44
Technical Overview
45
Bluetooth Radio Specification
46
Design considerations
Noise, interference
power
spectrum
Recovered data signal
Data signal x(t)
cost
Goal

• high bandwidth
• conserve battery power
• cost lt 10

47
EM Spectrum
S/W radio
FM radio
TV
TV
AM radio
cellular
?
X rays
Gamma rays
visible
UV
infrared
?
1 MHz
1 kHz
1 GHz
1 THz
1 PHz
1 EHz
Propagation characteristics are different in each
frequency band
48
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
cordless phones baby monitors Wireless LANs
802.11 Bluetooth Microwave oven
49
Bluetooth Radio Link
1Mhz
. . .
79
1
2
3
83.5 Mhz

• frequency hopping spread spectrum
• 2.402 GHz k MHz, k0, , 78
• 1,600 hops per second
• GFSK modulation
• 1 Mb/s symbol rate
• transmit power
• 0 dbm (up to 20dbm with power control)

50
Review of Basic Concepts
51
Baseband
Applications
SDP
RFCOMM
Audio
L2CAP
Link Manager
Baseband
RF
52
Bluetooth Physical Link

• Point to point link
• master - slave relationship
• radios can function as masters or slaves

53
Connection Setup

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

54
Inquiry on Time Axis
f1
f2
Slave1
Master
Slave2
55
Piconet Formation

• Page - scan protocol
• to establish links with nodes in proximity

56
Addressing

• Bluetooth device address (BD_ADDR)
• 48 bit IEEE MAC address

• Active Member address (AM_ADDR)
• 3 bits active slave address
• all zero broadcast address

• Parked Member address (PM_ADDR)
• 8 bit parked slave address

57
Piconet Channel
FH/TDD
f1
f4
f5
f2
f3
f6
m
s1
s2
625 ?sec
1600 hops/sec
58
Multi Slot Packets
FH/TDD
f1
f4
f5
f6
m
s1
s2
625 µsec
Data rate depends on type of packet
59
Physical Link Types

• Synchronous Connection Oriented (SCO) Link
• slot reservation at fixed intervals

• Asynchronous Connection-less (ACL) Link
• Polling access method

m
s1
s2
60
Packet Types
Data/voice packets
Control packets
Voice
data
ID Null Poll FHS DM1
HV1 HV2 HV3 DV
DH1 DH3 DH5
DM1 DM3 DM5
61
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
62
Access Code
72 bits
Access code
Payload
Header
Purpose

• Synchronization
• DC offset compensation
• Identification
• Signaling

X
63
Packet Header
54 bits
Access code
Payload
Header
Purpose

• Addressing (3)
• Packet type (4)
• Flow control (1)
• 1-bit ARQ (1)
• Sequencing (1)
• HEC (8)

16 packet types (some unused)
Broadcast packets are not ACKed
For filtering retransmitted packets
Verify header integrity
total
18 bits
Encode with 1/3 FEC to get 54 bits
64
Voice Packets (HV1, HV2, HV3)
54 bits
240 bits
72 bits
366 bits
Access code
Header
30 bytes
Payload
HV1
10 bytes
1/3 FEC
20 bytes
2/3 FEC
HV2
30 bytes
HV3
65
Data Packet Types
2/3 FEC
No FEC
66
Inter Piconet Communication
Cordless headset
Cell phone
Cell phone
Cordless headset
67
Scatternet
68
Scatternet, Scenario 2
How to schedule presence in two piconets?
Forwarding delay ?
Missed traffic?
69
Baseband Summary

• TDD, frequency hopping physical layer
• Device inquiry and paging
• Two types of links SCO and ACL links
• Multiple packet types (multiple data rates with
  and without FEC)

70
Link Manager Protocol

• Setup and management
• of Baseband connections
• Piconet Management
• Link Configuration
• Security

71
Piconet Management

• Attach and detach slaves
• Master-slave switch
• Establishing SCO links
• Handling of low power modes ( Sniff, Hold, Park)

Paging
req
Master
Slave
response
72
Low Power Mode (hold)
Hold offset
Slave
Hold duration
Master
73
Low Power Mode (Sniff)
Sniff offset
Sniff duration
Slave
Sniff period
Master

• Traffic reduced to periodic sniff slots

74
Low Power Mode (Park)
Slave
Beacon instant
Master
Beacon interval

• Power saving keep more than 7 slaves in a
  piconet
• Give up active member address, yet maintain
  synchronization
• Communication via broadcast LMP messages

75
Connection Establishment Security

• Goals
• Authenticated access
• Only accept connections from trusted devices
• Privacy of communication
• prevent eavesdropping

Paging
LMP_host_conn_req
LMP Accepted

• Constraints
• Processing and memory limitations
• 10 headsets, joysticks
• Cannot rely on PKI
• Simple user experience

Security procedure
Master
Slave
LMP_setup_complete
LMP_setup_complete
76
Authentication

• Authentication is based on link key (128 bit
  shared secret between two devices)
• How can link keys be distributed securely ?

challenge
response
Claimant
Verifier
accepted
Link key
Link key
77
Pairing (Key Distribution)

• Pairing is a process of establishing a trusted
  secret channel between two devices (construction
  of initialization key Kinit)
• Kinit is then used to distribute unit keys or
  combination keys

PIN Claimant address
PIN Claimant address
Claimant
Verifier
Random number
challenge
Random number
Random number
response
accepted
Kinit
Kinit
78
Link Manager Protocol Summary

• Piconet management
• Link configuration
• Low power modes
• QoS
• Packet type selection
• Security authentication and encryption

79
L2CAP
Logical Link Control and Adaptation Protocol
Applications
SDP
RFCOMM
Data

• L2CAP provides
• Protocol multiplexing
• Segmentation and Re-assembly
• Quality of service negotiation

Audio
L2CAP
Link Manager
Baseband
RF
80
L2CAP
Logical Link Control and Adaptation Protocol
Applications
SDP
RFCOMM
Data

• L2CAP provides
• Protocol multiplexing
• Segmentation and Re-assembly
• Quality of service negotiation

Audio
L2CAP
Link Manager
Baseband
RF
81
Why baseband isnt sufficient?
reliable, flow controlled
Baseband
in-sequence, asynchronous link

• Baseband packet size is very small (17min, 339
  max)
• No protocol-id field in the baseband header

82
Need a Multiprotocol Encapsulation Layer
IP
RFCOMM
IP
RFCOMM
reliable, in-order, flow controlled, ACL link

• What about
• Reliability?
• Connection oriented or connectionless?
• integrity checks?

• Desired features
• Protocol multiplexing
• Segmentation and re-assembly
• Quality of service

83
Segmentation and Reassembly
Payload
Length
Baseband packets
CRC
CRC
CRC
start of L2CAP
continuation of L2CAP
continuation of L2CAP

• cannot cope with re-ordering or loss
• mixing of multiple L2CAP fragments not allowed
• If the start of L2CAP packet is not acked, the
  rest should be discarded

min MTU 48 672 default
84
Multiplexing and Demultiplexing
IP
RFCOMM
IP
RFCOMM
Circuit or connection-less ?
Why is L2CAP connection oriented ?

• Baseband is polling based
• Bandwidth efficiency
• - carry state in each packet Vs. maintain it at
  end-points
• Need ability for logical link configuration
• MTU
• reliability (Flush timeout option)
• QoS (token bucket parameter negotiation)

85
L2CAP Channels
CID
Payload
Length
signaling channel
master
Slave 1
Slave 3
01
01
01
01
CID
CID
CID
CID
CID
CID
data channel
CID
01
Signaling channel CID does not uniquely
determine the identity of the source L2CAP entity
Signaling channel for 1) connection
establishment 2) channel configuration 3)
disconnection
CID
01
Slave 2
86
L2CAP Connection an Example
Target
Initiator
L2CAP_ConnectReq
Establishment
L2CAP_ConnectRsp
L2CAP_ConfigReq
Configuration
L2CAP_ConfigRsp
MTU, QoS reliability
L2CAP_ConfigReq
L2CAP_ConfigRsp
Data transfer
L2CAP_DisconnectReq
Termination
L2CAP_DisconnectRsp
87
L2CAP Packet Format (Connectionless)
Not fully developed yet.
88
L2CAP Summary

• Simplicity
• Low overhead
• Limited computation and memory
• Power efficient

Design constraints
Assumptions about the lower layer

• Reliable, in-order delivery of fragments
• Integrity checks on each fragment
• Asynchronous, best effort point-to-point link
• No duplication
• Full duplex

Service provided to the higher layer

• Protocol multiplexing and demultiplexing
• Larger MTU than baseband
• Point to point communication

89
Bluetooth Service Discovery Protocol
Applications
SDP
RFCOMM
Data
Audio
L2CAP
Link Manager
Baseband
RF
90
Example usage of SDP

• Establish L2CAP connection to remote device
• Query for services
• search for specific class of service, or
• browse for services
• Retrieve attributes that detail how to connect to
  the service
• Establish a separate (non-SDP) connection to use
  the service

91
Serial Port Emulation using RFCOMM
Applications
SDP
RFCOMM
Data

• Serial Port emulation on top of a packet oriented
  link
• Similar to HDLC
• For supporting legacy apps

Audio
L2CAP
Link Manager
Baseband
RF
92
Serial Line Emulation over Packet based MAC
RFCOMM
RFCOMM
L2CAP
L2CAP

• Design considerations
• framing assemble bit stream into bytes and,
  subsequently, into packets
• transport in-sequence, reliable delivery of
  serial stream
• control signals RTS, CTS, DTR

93
IP over Bluetooth V 1.0
Applications
SDP
RFCOMM
GOALS
Data

• Internet access using cell phones
• Connect PDA devices laptop computers to the
  Internet via LAN access points

Audio
L2CAP
Link Manager
Baseband
RF
94
LAN Access Point Profile
IP
Access Point
PPP
RFCOMM
L2CAP
Baseband
95
Inefficiency of Layering
Palmtop
LAN access point
IP
IP
packet oriented
PPP
PPP
rfc 1662
rfc 1662
byte oriented
RFCOMM
RFCOMM
packet oriented
L2CAP
L2CAP

• Emulation of RS-232 over the Bluetooth radio link
  could be eliminated

96
Terminate PPP at LAN Access Point
Palmtop
Access Point
IP
IP
PPP
ethernet
PPP
RFCOMM
RFCOMM
Bluetooth
Bluetooth

• PPP server function at each access point
• management of user name/password is an issue
• roaming is not seamless

97
L2TP Tunneling
Palmtop
Access Point
PPP server
IP
IP
PPP
PPP
RFCOMM
RFCOMM
Bluetooth
Bluetooth

• Tunneling PPP traffic from access points to the
  PPP server
• 1) centralized management of user name/password
• 2) reduction of processing and state maintenance
  at each access point
• 3) seamless roaming

98
Seamless Roaming with PPP
Server
AP1
AP2
MAC level registration
palmtop
99
IP over Bluetooth v 1.1 BNEP
Access Point
IP
Bluetooth Network Encapsulation Protocol (BNEP)
provides emulation of Ethernet over L2CAP
BNEP

• BNEP defines
• a frame format which includes IEEE 48 bit MAC
  addresses
• A method for encapsulating BNEP frames using
  L2CAP
• Option to compress header fields to conserve
  space
• Control messages to activate filtering of
  messages at Access Point

L2CAP
Baseband
100
Bluetooth Current Market Outlook
101
Market Forecasts for Year 2005
Cahners In-stat (2000 forcast)
revised (2001 forcast)
Merrill Lynch (2000 forcast)
5.4 bn
revised (2001 forcast)
4.4 bn
2.1 bn
4.3 bn
1.4 bn
2.2 bn
4.4
1.5 bn
995 m
3.6
2.02
Revenue
Units sold annually
Chip price
102
Bluetooth Value Chain
Wireless Carriers
Conspicuously missing
Stack providers
Software vendors
Integrators
Silicon
Radio
103
Value to Carriers Synchronization and Push

• More bits over the air
• Utilization of unused capacity during non-busy
  periods
• Higher barrier for switching service providers

104
Value to Carriers Cell phone as an IP Gateway
Will Pilot and cell phone eventually merge?

• More bits over the air
• Enhanced user experience
• Palmpilot has a better UI than a cell phone
• Growth into other vertical markets

105
Value to Carriers Call Handoff
Cordless base
Threat or opportunity?

• More attractive calling plans
• Alleviate system load during peak periods
• Serve more users with fewer resources

106
Biggest Challenges facing Bluetooth

• Interoperability
• Always a challenge for any new technology
• Hyped up expectations
• Out of the box ease of use
• Cost target 5
• Critical mass
• RF in silicon
• Conflicting interests business and engineering

107
References

• 1 IEEE 802.11, Wireless LAN MAC and Physical
  Layer Specification, June 1997.
• 2 Hirt, W. Hassner, M. Heise, N. IrDAVFIr
  (16 Mb/s) modulation code and system design.
  IEEE Personal Communications, vol.8, (no.1),
  IEEE, Feb. 2001.
• 3 Lansford, J. Bahl, P. The design and
  implementation of HomeRF a radio frequency
  wireless networking standard for the connected
  home. Proceedings of the IEEE, IEEE, Oct. 2000.
• 4 Specification of Bluetooth System, ver. 1.0,
  July 1999

108
References (cnt)

• 5 Haartsen, J.C. The Bluetooth radio system.,
  IEEE Personal Communications, IEEE, Feb. 2000.
• 6 Haartsen, J.C. Bluetooth towards ubiquitous
  wireless connectivity., Revue HF, Soc. Belge
  Ing. Telecommun. Electron, 2000. p.816.
• 7 Rathi, S. Bluetooth protocol architecture.
  Dedicated Systems Magazine, Dedicated Systems
  Experts, Oct.Dec. 2000.
• 8 Haartsen, J.C. Mattisson, S. Bluetootha
  new lowpower radio interface providing
  shortrange connectivity. Proceedings of the
  IEEE, IEEE, Oct. 2000.
• 9 Gilb, J.P.K Bluetooth radio architectures.
  2000 IEEE Radio Frequency Integrated Circuits
  (RFIC) Symposium Digest of Papers, Boston, MA,
  USA, 1113 June 2000.

109
References (cnt)

• 10 N. Benvenuto, G. Cherubini, Algoritmi e
  circuiti per le telecomunicazioni, Ed. Libreria
  Progetto.
• 11 The Bluetooth Special Interest Group,
  Documentation available at http//www.bluetooth.co
  m/
• 12 IEEE 802.15 Working Group for WPANs
  http//www.manta.ieee.org/groups/802/15/
• 13 Barker, P. Boucouvalas, A.C. Vitsas, V.
  Performance modelling of the IrDA infrared
  wireless communications protocol. International
  Journal of Communication Systems, vol.13, Wiley,
  Nov.Dec. 2000.
• 14 Tokarz, K. Zielinski, B. Performance
  evaluation of IrDA wireless transmission. 7th
  Conference on Computer Networks, Zakopane,
  Poland, 1416 June 2000.
• 15 ETSI RES, Digital European Cordless
  Telecommunications (DECT), Common interface Part
  1 Overview, ETS 300 1751, 1996.