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Wireless LANs (cont). Bluetooth. Landline. Cable Replacement. Data/Voice Access Points. Personal Ad-hoc Networks. What Is Bluetooth ?. Example. Some Bluetooth Facts…. 2.4 GHz ISM Open band Globally free available frequency, 89 MHz of spectrum available

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what is bluetooth

Landline

Cable Replacement

Data/Voice Access Points

Personal Ad-hoc Networks

What Is Bluetooth?
some bluetooth facts
Some Bluetooth Facts….
  • 2.4 GHz ISM Open band
    • Globally free available frequency, 89 MHz of spectrum available
    • FHSS radio (1600 hops/s and 79 frequencies)
  • 10 -100 m range
    • 8 active devices per piconet (share datarate)
    • Up to 10 piconets in bubble (full datarate)
  • 1 Mbps gross rate
  • Simultaneous voice/data capable
    • 432 Kbps (full duplex), 721/56 Kbps (asymmetric)

or

    • 3 simultaneous full duplex voice channels per piconet

or

    • a combination of data and voice
slide7

Network Topology – Piconet

  • Piconets created ad-hoc
  • Master-Slave concept
  • Piconet defined by itsfrequency hopping sequence

slave 3

slave1

master

slave 2

piconet establishment

UnconnectedStandby

ConnectingStates

ActiveStates

Low PowerModes

master

connecting

slaves

active slave

parked slave

standby

Piconet establishment
  • Ad-hoc setup
  • Connection oriented
  • Power save modes
the piconet

or

The piconet

D

  • All devices in a piconet hop together
    • To form a piconet: master gives slaves its clock and device ID
      • Hopping pattern determined by device ID(48-bit)
      • Phase in hopping pattern determined by Clock
  • Non-piconet devices are in standby
  • Piconet Addressing
    • Active Member Address (AMA, 3-bits)
    • Parked Member Address (PMA, 8-bits)

A

E

B

C

fh tdd channel
FH/TDD Channel

f(k)

f(k+1)

f(k+2)

master

t

slave

t

One slot: 625 ms

One frame: 1250 ms

packet format

0-2745

72

54

access code

packet header

payload

Packet Format
packet types
Packet Types

Access code Header Payload

72 bits 54bits 0-2475 bits

Bluetooth Packet

  • Bluetooth Protocol supports 16 packet types, 15 types defined

4 Control packets common to both links

POLL,NULL,FHS and ID

4 SCO packets used to carry voice with different payload lengths.

HV1,HV2,HV3 and DV, where DV carries both voice and data

7 ACL packets with different payload lengths

DM1,DM3,DM5,DH1,DH3,DH5 and AUX1

Carries data only

multi slot packets

625 s

f(k)

f(k+1)

f(k+2)

f(k+3)

f(k+4)

f(k+5)

f(k)

f(k+3)

f(k+4)

f(k+5)

f(k)

f(k+5)

Multi-slot Packets
error handling
Error handling

72bits

0-2745bits

54bits

  • Forward-error correction (FEC)
    • headers are protected with 1/3 rate FEC and 8 bit CRC (HEC)
    • payloads may be FEC protected
      • 1/3 rate: simple bit repetition (SCO packets only)
      • 2/3 rate: (10,15) shortened Hamming code
      • 3/3 rate: no FEC
  • ARQ (ACL packets only)
    • 16-bit CRC (CRC-CCITT) & 1-bit ACK/NACK
    • 1-bit sequence number

payload

access code

header

physical link definition
Physical Link Definition
  • Synchronous Connection-Oriented (SCO) Link
    • circuit switching
    • symmetric, synchronous services
    • slot reservation at fixed intervals
  • Asynchronous Connection-Less (ACL) Link
    • packet switching
    • (a)symmetric, asynchronous services
    • polling access scheme
mixed link example

SCO

ACL

SCO

ACL

ACL

SCO

SCO

ACL

Mixed Link Example

MASTER

SLAVE 1

SLAVE 2

SLAVE 3

data rates kb s

TYPE

symmetric

asymmetric

DM1

108.8

108.8

108.8

DH1

172.8

172.8

172.8

DM3

256.0

384.0

54.4

DH3

384.0

576.0

86.4

DM5

286.7

477.8

36.3

DH5

432.6

721.0

57.6

Data Rates (kb/s)
slide18

LAN

access point

access point

mobile phone

mobile phone

headset

headset

printer

printer

laptop

laptop

master

laptop

laptop

slave

mouse

mouse

master/slave

Multiple Piconets: A Scatternet

slide19

Multiple Piconets: A Scatternet

master

slave

master/slave

slide20

Ad-hoc IP networking on Bluetooth

(MANET) IP Hosts

Bluetooth

Link and Baseband

Layer

slave 3

slave 1

slave 5

slave 4

master

master

slave 2

some issues
Some issues….
  • Scatternet - A device present in more than one piconet
    • How to jump efficiently between piconets?
    • Delay sensitive applications?
    • Things happening in “sleeping” piconets?

LAN

access point

scatternet forming reforming
Scatternet Forming/Reforming
  • “Optimal” scatternet configuration depends on
    • Connectivity and Node density
    • Traffic Distribution (Traffic matrix)
    • Mobility&Traffic dynamics - steady state ever reached?
    • Integration of connection establishment and (ad-hoc) routing?

At t...

At t+D t.

work your bluetooth network

s

s

s

s

s

s

s

m

s

m

s

s

m

s

s

m

”Work” your Bluetooth Network
  • Bluetooth handles overlaid Piconets well
  • Overall capacity gained by setting up new piconets
smart scatternet

S-M 10 % of traffic

S-M 55 % of traffic

S-S 45 % of traffic

S-S 90 % of traffic

s

s

s

s

m

s

s

s

m

s

s

s

s

s

Smart Scatternet...
  • Move out large slave to slave traffic
  • Still part of old piconet - a scatternet

P2

s

s

P1

P1

m

s

s

s

slide25

IP

L2(Broadcast segment)

Ad-hoc networking

slave 3

slave 1

slave 5

slave 4

master

master

Bluetooth

slave 2

piconet scheduling

2

2

1

1

3

3

2

2

1

1

3

3

Piconet scheduling

slave 3

slave1

  • Intra-piconet scheduling
    • Master controlled polling algorithm
    • Round Robin?
  • Inter-piconet scheduling
    • One transceiver
    • Different FHS

master

slave 2

master

slave 3

slave 4

4

4

inter piconet timing

A

P2

s

P1

s

s

s

m2

s

m1

s

s

s

s

s

Inter-piconet Timing
  • Interpiconet communication may be “costly”
  • An interpiconet unit active in only one piconet at a time
  • SNIFF Mode - Periodic presence in each piconet

INQUIRY Scan/PAGE Scan

P1

P2

sniff mode
SNIFF Mode
  • SNIFF Parameters
    • Tsniff
    • max(Nsniffattempt, Nsnifftimeout) = Wsniff
  • Approximately one frame lost per “Piconet switch”
  • Trade off: Delay vs. Throughput
    • Delay: Tsniff
    • Throughput:

WsniffP2

TsniffP1

P1

P2

WsniffP2

TsniffP2

bluetooth experiments gerla m et al tyrrenia conf sept 2000
Bluetooth Experiments Gerla, M et al,Tyrrenia Conf, sept 2000
  • Experiment #!:TCP throughput in a single piconet. Throughput versus the no. of TCP connections. Each TCP connection starts from a different slave on the common piconet, and goes through the access point (BT master).
  • Experiment #2: TCP throughput when multiple piconets are used in parallel. Each piconet here supports a separate TCP connection.
  • Experiment #3: TCP and IP Telephony in a multiple piconet configuration. IP Telephony uses ACL channel. Question: can TCP and Telephony coexist?
slide30

IP backbone

IP backbone

IP backbone

IP router

IP router

IP router

LAN

LAN

LAN

M

M

S

M

1

1

1

1

S

M

M

M

M

M

S

M

3

3

2

3

2

2

2

3

S

S

(a)

(b)

(c)

Fig. 4.

tcp and ip telephony
TCP and IP Telephony
  • Voice carried on the ACL channel
  • Four piconets
  • In each piconet: 1 TCP and 6 Voice connections
  • TCP connections “always on” (file transfers)
  • Voice: ON-OFF model; 8Kbps coding rate
  • Voice packets: 20ms packetization -> 20 bytes
  • With header overhead: voice pkt = 30 bytes
exp 3 wavelan 802 11 tcp voip1
Exp #3: WaveLan 802.11: TCP + VoIP

With 750 ms playout buffer, 5% packets lost

simulation what have we learned
Simulation: what have we learned?
  • Bluetooth performance predictable, dependable
  • Fairsharing across TCP connections (IEEE 802.11 is unfair, “capture”- prone)
  • BT aggregate throughput exceeds IEEE 802.11
  • BT supports voice well even in heavy TCP load (IEEE 802.11 cannot deliver voice with TCP load)
  • BT not overly sensitive to microwave ovens

Future work

  • BT load sensitive polling schedule
  • BT in low latency applications (sensors on walls)
  • BT scatternets (formation, schedules, routing etc)
  • BT vs UMTS comparison
bluetooth sig2 pan wg
Bluetooth SIG2 - PAN WG
  • Personal Area Network
  • Ad-hoc Bluetooth work groups
  • QoS support (audio/video)
  • Possibly: “associated” members
    • opens up for academia
    • research oriented work
bluetooth program update
Bluetooth Program Update
  • Final Specification published Monday 7/26/99
    • Result of work from ~200 engineers
    • Updated Specification 1.0 B published 12/1/99
  • SIG Membership Exceeds 1,700 Companies!
    • Becoming the choice for wireless connectivity
    • Membership list at www.bluetooth.com
  • Program on Track for Products in 2000
    • Products announced
    • Next step is Qualification Program
  • Specification is basis for the proposed IEEE 802.15.1 standard
pan impact on internet access for mobile devices
PAN Impact on Internet Access for Mobile Devices
  • PAN allows sharing of “gateway” device
    • E.g., Only one cellular “modem” needed
    • E.g., Only one ADSL connection needed
  • PAN allows sharing of access “tariff”
    • All personal devices share same account
  • Allows multiple combinations of wireless and wired technology for Internet access with one or two communication interfaces
pan to cellular data network
PAN to Cellular Data Network
  • Available today using cables or IR
  • 2nd generation cellular better than analog
  • Cost and speed are still issues
  • RF value add is wireless connectivity without “line of sight” limitations
  • Also allows “unconscious” data reception

PAN to WWAN

pan to wired infrastructure

PSTN, ISDN,HomePNA, xDSL

PAN to Wired Infrastructure
  • Wireless “last hop” to the Internet
  • Public kiosks provide alternative to wireless wide-area networks

PAN to LAN/WAN

summary
Summary
  • Bluetooth is a radio system (not a radio)
    • Building block for personal area networks
    • More information available at:

http://www.bluetooth.com

  • PAN will improve the cost and convenience of achieving mobile Internet access