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WPANs (Bluetooth)

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Title: 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.
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