Transcript Lecture slides ppt

OTHER NETWORKS
c@Irek Defée
MULTIMEDIA SYSTEMS
CABLE MODEMS
c@Irek Defée
MULTIMEDIA SYSTEMS
•
•
•
CABLE TV DOES NOT SUFFER FROM
THE TELEHONE CABLE PROBLEM
TV CABLE IS VERY BROADBAND,
BANDWIDTH AT LEAST TO 1 GHz,
SIGNAL TRANSMISSION IS
EXCELLENT
CABLE TV NETWORK
ARCHITECTURE IS A PROBLEM
c@Irek Defée
MULTIMEDIA SYSTEMS
• ALL USERS SHARE THE SAME CABLE
• CABLE BANDWIDTH IS DIVIDED
INTO ’TV’ CHANNELS
• A TV CHANNEL CAN BE USED AS A
DATA CHANNEL USING DIGITAL
MODULATION, SUCH CHANNEL CAN
CAN HAVE E.G. 50 Mb/s CAPACITY
THE MORE USERS WOULD SHARE IT
THE LESS BANDWIDTH THEY GET
c@Irek Defée
MULTIMEDIA SYSTEMS
• SECOND PROBLEM: TV CHANNELS
ARE USED FOR RECEIVING SIGNALS
HOW USERS CAN SEND THEIR
DATA?
• CABLE NETWORK MUST BE
REDESIGNED TO
- ALLOW DATA SENDING USING
CABLE MODEM
- ALLOW SEPARATE STREAM FOR
EACH USER
c@Irek Defée
MULTIMEDIA SYSTEMS
• STANDARDS WERE DEFINED FOR
THIS
- FOR RECEIVING DATA ANY TV
CHANNEL CAN BE ALLOCATED
IN THE BAND 70-130 MHz AND
300-862 MHz
- FOR SENDING DATA THE BAND 5-65
MHz IS ALLOCATED
c@Irek Defée
MULTIMEDIA SYSTEMS
• SIGNAL MODULATION IN CABLE
MODEMS
QPSK - QUADRATURE PHASE SHIFT
KEYING
QAM – QUADRATURE AMPLITUDE
MODULATION
11
10
.
00
PHASE OF THE SIGNAL
IS CHANGED (HERE FOUR
VALUES ARE USED)
01
c@Irek Defée
MULTIMEDIA SYSTEMS
• PHASE AND AMPLITUDE CAN BE
CHANGED – QAM
HERE WE CAN ASSIGN
3 BITS TO EACH VALUE
OF AMPLITUDE AND PHASE
000
THE MORE AMPLITUDE AND PHASE VALUES THE MORE
INFORMATION CAN BE SEND, BUT SIGNAL IS MORE
SENSITIVE TO NOISE
c@Irek Defée
MULTIMEDIA SYSTEMS
16-QAM BIT ASSIGNMENT
c@Irek Defée
MULTIMEDIA SYSTEMS
• FOR THE UPSTREAM CHANNEL
(FROM THE USER) 0.2, 1 OR 2 MHz
CHANNELS CAN BE USED, THEY
ARE QPSK MODULATED. DATA RATE
IS 256 kb/s, 1.5 Mb/s, 3 Mb/s, 6 Mb/s
• FOR THE DOWNSTREAM CHANNEL
THE TV CHANNEL IS USED. 64 OR
256 QAM MODULATION, DATA RATE
30-50 Mb/s
c@Irek Defée
MULTIMEDIA SYSTEMS
• A SIMPLE SYSTEM IS THE ONE IN
WHICH ALL USERS SHARE THE SAME
CHANNEL, IT IS LIKE THE ETHERNET
BANDWIDTH DEPENDS ON THE
NUMBER OF USERS AND NETWORK
LOAD.
THIS SYSTEM IS A KIND OF LAN AND
IS RELATIVELY VERY CHEAP FOR
ITS BANDWIDTH
c@Irek Defée
MULTIMEDIA SYSTEMS
• MORE COMPLICATED SYSTEM IS THE ONE
IN WHICH USERS GET THEIR OWN
STREAMS
• HOW THIS CAN BE DONE?
- EACH 40 Mb/s CHANNEL IS ENOUGH
FOR 8-10 USERS
- MORE TV CHANNELS CAN BE
ALLOCATED TO DATA TRANSMISSION
• FOR EXAMPLE WITH 20 CHANNELS ONE
CAN GET 200 USERS
c@Irek Defée
MULTIMEDIA SYSTEMS
• CABLE TV NETWORK CAN BE
SPLIT AROUND HEADEND
AMPLIFIERS
DISTRIBUTION (FIBER OPTICS)
USERS (100-200 PER HEADEND)
c@Irek Defée
MULTIMEDIA SYSTEMS
• THUS FROM EACH CABLE HEADEND
USERS CAN BE SUPPLIED BY THEIR
OWN STREAMS
• CABLE TV NETWORK IS THUS ABLE
TO SUPPLY VERY MANY USERS WITH
HIGH BANDWIDTH NETWORKING
SERVICE
c@Irek Defée
MULTIMEDIA SYSTEMS
WIRLESS SYSTEMS
CELLULAR NETWORKS
c@Irek Defée
MULTIMEDIA SYSTEMS
THERE ARE SEVERAL METHODS FOR EFFICIENT
MANAGEMENT OF RADIO TRANSMISSION:
- FDM, FREQUENCY DIVISION MULTIPLEX
TRANSMITTERS USE DIFFERENT FREQUENCY
BANDS (example: television, radio)
-TDM, TIME DIVISION MULTIPLEX,
TRNSMITTERS ARE USED AT DIFFERENT TIMES
-SDM, SPATIAL DIVISION MULTIPLEX, TRNSMITTERS
OPERATE IN SEPARATED AREAS (mobile phones)
-CDM, CODE DIVISION MULTIPLEX, TRANSMITTERS
OPERATE WITH DIFFERENT ACCESS CODES
WHICH MINIMIZE INTERFERENCE (mobile phones)
If we have transmitters and receivers we can talk about Access
to the reception and systems are called CDMA, FDMA,...
c@Irek Defée
MULTIMEDIA SYSTEMS
THESE ACCESS SYSTEMS CAN BE USED IN ALL KIND
OF COMBINATIONS, TDMA/FDMA/SDMA ETC.
SYSTEMS CAN BE DESIGNED FOR OPTIMAL USE OF
RADIO WAVES WITH THOSE ACCESS SYSTEMS:
1. SDMA – IS A BASIS FOR CELLULAR SYSTEMS,
FREQUENCIES CAN BE REUSED IN
SEPARATED CELLS
THERE IS A
TRANSMITTER
IN THE CENTER
OF EACH CELL
c@Irek Defée
MULTIMEDIA SYSTEMS
• THE COST OF THIS IS THAT ONE NEEDS TO
IMPLEMENT HANDOVER WHEN MOVING
BETWEEN THE CELLS AND ALSO TRACK
THE LOCATION USERS
• WITHIN THE CELLS TDMA/FDMA, CDMA CAN
BE REUSED IN DIFFERENT COMBINATIONS
EXAMPLE: THE GSM SYSTEM: OPERATES IN
TWO BANDS
900 AND 1800 MHz, WIDTH 25 AND 75 MHz,
WIDTH OF ONE CHANNEL – 200 kHz FDMA
CHANNEL DIVIDED INTO 8 time slots - TDMA
WHY? IT SAVES THE NUMBER OF
TRANSMITTERS
c@Irek Defée
MULTIMEDIA SYSTEMS
- IN ADDITION GSM THE SYSTEM HAS ALSO
A KIND OF CDMA – FREQUENCY HOPPING:
FREQUENCY BAND CAN BE CHANGED FROM
TIME SLOT TO TIME SLOT ACCORDING TO
SPECIFIC PATTERN. THIS LEADS TO
STATISTICALLY BETTER USE.
-HOW MANY USERS CAN BE SUPPORTED?
IF ONE BASE STATION TAKES 5 MHz IT
CAN SUPPORT 200 USERS (175). MINIMUM
CELL SIZE IS 100-500M(?). SO WE CAN GET
HIGH DENSITY OF USERS/km2
c@Irek Defée
MULTIMEDIA SYSTEMS
•
THE GSM WIRELESS CELLULAR
SYSTEM STARTED AS FOR TELEPHONE
APPLICATIONS
THIS SYSTEM IS QUICKLY
EVOLVING AND WILL CONTINUE TO
DO SO IN THE FUTURE DATA
TRANSMISSION AND MULTIMEDIA WILL
BE MOST IMPORTANT
c@Irek Defée
MULTIMEDIA SYSTEMS
•
GSM UPGRADES
- GPRS – PACKET SWITCHING,
CONNECTIONLESS SERVICE
- HSCSD – HIGH SPEED CIRCUIT
SWITCHED DATA
- EDGE – BANDWIDTH INCREASE
WITH NEW MODULATION BASED
ON 8-PSK
c@Irek Defée
MULTIMEDIA SYSTEMS
Maximum Data Rate for New Systems
Standards
Implementation
GSM Data
9.6 kbps
9.6 kbps
HSCSD
57.6 kbps
28.8 kbps
GPRS
171 kbps
57.6 kbps
EDGE
470 kbps
< 470 kbps
WCDMA
2048 kbps
384 kbps
ISDN
144 kbps
144 kbps
c@Irek Defée
MULTIMEDIA SYSTEMS
•
1. GPRS
- PACKET SWITCHING RUNNING IN
FREE CAPACITY OF GSM SLOTS
- VERY FLEXIBLE
- SEVERAL CODING SCHEMES
- FLEXIBLE USE OF TIME SLOTS
c@Irek Defée
MULTIMEDIA SYSTEMS
GPRS PACKETS ALLOCATION
 Radio resources allocation
– either to Circuit Switched service
– or to Packet Switched service
TDMA frame
TRX : GPRS & GSM
TS number
GSM only
0
GPRS only
7
GSM or GPRS
 Priority can be given to one service while
ensuring minimum capacity for the other one
c@Irek Defée
MULTIMEDIA SYSTEMS
Coding schemes in GPRS
• 4 coding schemes for packet transfers
information
protection
data rates (Kbits/s)
thus data rates
increase
15.6
13.4
9. 05
CS2 CS3
CS1 : same as GSM
measurements reporting
c@Irek Defée
MULTIMEDIA SYSTEMS
CS4 : no protection
21.4
CS
GPRS coverage
• New design thresholds
– depending on coding scheme
– due to decreasing protection / interferences
• On existing networks
– "concentric" GPRS coverage
CS4
GSM only cell
c@Irek Defée
enabling
GPRS
MULTIMEDIA SYSTEMS
GSM
coverage
CS3
CS2
CS1
Coverage of GPRS
Cell Radius
Base Station
CS1 (1.06)
GSM Voice (1)
CS2 (0.82)
CS3 (0.72)
CS4 (0.42)
There is no significant change in coverage from GSM to GPRS CS1 and CS2
c@Irek Defée
MULTIMEDIA SYSTEMS
Traffic management
• GSM & GPRS cell :
– allocation of radio resources (time slots) to the
services
– then allocation of GPRS resources to the users
• Radio resources management efficiency
depends on :
– target for qualities of service
– operator strategy and parameters set
c@Irek Defée
MULTIMEDIA SYSTEMS
New GPRS Network Elements
BTS
BSC
MSC/
VLR
GMSC
Existing Elements
HLR
PCU
SGSN
GPRS Backbone
IP Network
GGSN
New Elements
BG = Border Gateway
CG = Charging Gateway
BG
DNS = Domain Name Systems
PCU = Packet Control Unit
SGSN = Serving GPRS Support Node
GGSN = Gateway GPRS Support Node
BTS = Base Transceiver Station
BSC = Base Station Controller
MSC = Mobile Services Switching Centre
GMSC = Gateway MSC
c@Irek Defée
CG
DNS
MULTIMEDIA SYSTEMS
THE GPRS TRANSPORT PLANE
Application
IP / X.25
IP / X.25
IP
TID
SNDCP
SNDCP
GTP
GTP
LLC
IP
IP
TLLI
LLC
LLC Relay
RLC
RLC
BSSGP
BSSGP
Frame
Relay
L2
MAC
Frame
Relay
L2
MAC
GSM PL
GSM PL
L1bis
L1bis
L1
L1
Um
MS
Gb
BSS
Gn
SGSN
Gi
GGSN
In order to reach their final destination, data coming from external network are
tunnelled twice: into GTP packets in the Core Network and into LLC frames
(SNDCP allows multi-protocol) in the Access Network.
c@Irek Defée
MULTIMEDIA SYSTEMS
THE THREE LAYER TRANSPORT PLANE
IN GPRS BACKBONE
X25 end to end
IP end to end
LLC tunnel layer
RADIO specific
GTP tunnel layer
GPRS IP backbone
L2
3 layer
stack
SGSN
GGSN
One of the requirements in the original GPRS design was providing a system
being able to support in the same way IP and X25 data. Consequently GPRS
backbone was not fully optimized for IP data and a general purpose tunneling
protocol was designed for this. As a result the GPRS transport plane is
characterized by an heavy 3 layer protocol stack. (e.g. the use of IP over TCP over
GTP over TCP over IP is allowed in the GPRS backbone)
c@Irek Defée
MULTIMEDIA SYSTEMS
•
HSCSD
- CIRCUIT SWITCHING BY
RESERVATION OF SEVERAL TIME
SLOTS (UP TO 4) IN GSM
- IT IS SIMPLE AND PROVIDES MUCH
MORE BANDWIDTH BUT IT TAKES
TIME FOR CONNECTION
- HOW HSCSD COMPARE FOR
DATA RATES?
c@Irek Defée
MULTIMEDIA SYSTEMS
HSCSD User Data Rate
transparent service
non transparent service
up- / downlink 100% coverage 95% coverage 100% coverage 95% coverage
1+1
9.6
14.4
9.6
13.2
2+2
19.2
28.8
19.2
26.4
1+3
-----28.8
39.6
1+4
-----38.4
53.8
GPRS User Data Rate
Coding # of timeslots
Scheme
1
CS-1
9,05
CS-2
13,4
CS-3
15,6
CS-4
21,4
c@Irek Defée
2
18,1
26,8
31,2
42,8
3
27,15
40,2
46,8
64,2
4
36,2
53,6
62,4
85,6
5
45,25
67
78
107
MULTIMEDIA SYSTEMS
6
54,3
80,4
93,6
128,4
7
63,35
93,8
109,2
149,8
8
72,4
107,2
124,8
171,2
GSM Wireless Data Development Steps
High Speed Data Circuits
HSCSD n*14.4 (3*14.4 = 43.2)
3Q 1999
3Q 2000
High Speed Packet Capabilities
GPRS (e.g. 3* 13.4 = 40.2)
c@Irek Defée
MULTIMEDIA SYSTEMS
High Speed data circuits
HSCSD n*14.4 (3*14.4 = 43.2)
Corporate
Networks
GSM
BTS
BSC
MSC IWE
BTS
UDI
ISDN
PSTN
Internet
c@Irek Defée
MULTIMEDIA SYSTEMS
LAN
HSCSD: Pros and Cons
 HSCSD is available and offers four times higher bandwidth than the
today‘s GSM data service thus being very well compatible to the
standard fix network connection.
 HSCSD requires minor network upgrades only. No new network
elements are required at all. The invest is about a fifth of the one for
GPRS.
 HSCSD charging principles are well introduced in the network and
well accepted by the customers.
 HSCSD has a well defined QoS and can thus be used to address the
high expectation market segment.
 HSCSD is still circuit switched, i.e. the network load is not as
efficiently handled as with GPRS and thus an always on service is
hard to deliver.
 HSCSD is not the service to address the mass market with.
c@Irek Defée
MULTIMEDIA SYSTEMS
High Speed Packet Capabilities
GPRS (e.g. 3* 13.4 = 40.2)
GSM
BTS
HLR
MSC
BSS
SGSN
GGSN
other
PLMN
Border GW
GPRS backbone
FR / ATM
GGSN
Corporate
Networks
GGSN
c@Irek Defée
MULTIMEDIA SYSTEMS
Internet
GPRS: Pros and Cons
 GPRS offers up from mid 2000 a four times higher bandwidth
than the today‘s GSM data service.
 GPRS offers optimal network resource usage and optimized
mobile Internet access by introducing the packet switched
principle into GSM.
 GPRS allows to address the mass market with an always on
data service.
 Due to the IP character the GPRS QoS can not be guaranteed.
 GPRS requires major network upgrades and totally new
network elements. GPRS is expensive.
 Charging principles of GPRS are unclear and thus appropriate
interfaces to the billing systems do not exist.
c@Irek Defée
MULTIMEDIA SYSTEMS
New Mobile Applications
c@Irek Defée
MULTIMEDIA SYSTEMS
Smart
Messaging
HSCSD
GPRS
Banking
Traffic info & guidance
News
Weather
Ticket ordering
Info- & EntertainmentServices
Fleet management
File transfer
Corporate access / tele working
Online e-mail
Real-time applications
E-cash & payments
Audio & video on demand
Video surveillance services
(e.g. taxi, money transport)
Remote healthcare
Internet
Intranet
E-mail
Scheduler Access
Remote control
Monitoring
WAP / WML
HTTP / HTML
c@Irek Defée
MULTIMEDIA SYSTEMS
APPLICATION AREAS
Business
Private
• Intranet access
• Tele working
• Online e-mail / fax
With focus on
• Reliability
• Sufficient data rates
• Ease of Use
• Websurfing
• Electronic payment
services
• Mobile banking
With focus on
• Price
• Price
• Price
Best addressed by
Best addressed by
HSCSD
c@Irek Defée
GPRS
MULTIMEDIA SYSTEMS
• THIRD GENERATION CELLULAR
SYSTEMS
THESE SYSTEMS ARE BEING
DESIGNED FROM GROUND UP FOR
MULTIMEDIA APPLICATIONS:
- HIGH BANDWIDTH STREAMING
SERVICES
- PACKET BASED APPLICATIONS
c@Irek Defée
MULTIMEDIA SYSTEMS
• SIGNAL MODULATION TECHNOLOGY
IS WIDEBAND WCDMA,WHY?
SPECIFIC PROBLEM IN MOBILE
STREAMING IS CELL SWITCHING, OR
HANDOVER. HANDOVER IS CRITICAL
BECAUSE DATA MIGHT BE LOST.
IN CDMA ”SOFT” HANDOVER IS
POSSIBLE BECAUSE BANDS
CAN BE SHARED BY BASE STATIONS
c@Irek Defée
MULTIMEDIA SYSTEMS
What is UMTS? Called popularly 3G
•Universal Mobile Telecommunications
Service
•Member of IMT-2000 family
•Global multimedia
•Replacement (complement) for GSM
c@Irek Defée
MULTIMEDIA SYSTEMS
Spectrum allocation for UMTS
• 2x60MHz paired spectrum + 20 MHz
and 15 MHz unpaired = 155 MHz
c@Irek Defée
MULTIMEDIA SYSTEMS
UTRA – UMTS TERRESTRIAL RADIO ACCESS
UTRA Key Parameters
Multiple access scheme
Carrier spacing
Chip rate
Spreading factor range
Modulation
Pulse shaping
Frame length
Timeslots per frame
c@Irek Defée
FDD
W-CDMA
TDD
TD-CDMA
4·4 – 5·2 MHz
5 MHz
3·84 Mchip/s (Mcps)
4–512
1–16
QPSK
root raised cosine, roll-off = 0·22
10 ms
15
MULTIMEDIA SYSTEMS
Enhancements to 3G data capacity
• The data rate of basic 3G network is in the
range of 128-384 kb/s which is not much for current
demands
Upgrades were developed for significant increasing
of the data rate. They are called in general
HSPA – High Speed Packet Access, two methods
used are:
HSDPA - High Speed Downlink Packet Access
HSUPA – High Speed Uplink Packet Access
c@Irek Defée
MULTIMEDIA SYSTEMS
HSDPA
• High Speed Download Packet Access
• Information is sent to the users
HSDPA uses QPSK and 16-QAM modulation.
Users share data channel in 2 ms time frames
(several users may be served in one frame)
The data rate speed will depend on the type
of modulation, the number of users and priorities.
c@Irek Defée
MULTIMEDIA SYSTEMS
HSDPA data rates
Category
Max. number of
HS-DSCH codes
Modulation
Max. data rate
[Mbit/s]
1
5
QPSK and 16-QAM
1.2
2
5
QPSK and 16-QAM
1.2
3
5
QPSK and 16-QAM
1.8
4
5
QPSK and 16-QAM
1.8
5
5
QPSK and 16-QAM
3.6
6
5
QPSK and 16-QAM
3.6
7
10
QPSK and 16-QAM
7.3
8
10
QPSK and 16-QAM
7.3
9
15
QPSK and 16-QAM
10.2
10
15
QPSK and 16-QAM
14.4
11
5
QPSK only
0.9
12
5
QPSK only
1.8
The maximum data rate is theoretical peak rate for single user, effective data rate is in the range
1-2 Mb/s
c@Irek Defée
MULTIMEDIA SYSTEMS
HSUPA
• High Speed Uplink Packet Access
• Information is sent from the users
HSUPA is similar to HSDPA, speed lower
HSUPA Category
Max Uplink Speed
Category 1
0.73 Mbit/s
Category 2
1.46 Mbit/s
Category 3
1.46 Mbit/s
Category 4
2.93 Mbit/s
Category 5
2.00 Mbit/s
Category 6
5.76 Mbit/s
Category 7 (3GPP Rel7)
11.5 Mbit/s
c@Irek Defée
MULTIMEDIA SYSTEMS
PERSONAL WIRELESS
(Ad-Hoc) NETWORKS
c@Irek Defée
MULTIMEDIA SYSTEMS
Mobile Ad-Hoc Networks
• Temporary, wireless networks
• Direct peer-to-peer connection (no base stations)
• Connection created automatically when devices come
close to each other
– No a priori knowledge of other devices
– No administration
– No preconfiguration
• Data transmitted over air using electromagnetic waves
– Data is superimposed to a carrier signal
– Once superimposed, signal occupies a frequency band instead of a
single frequency
– When there are many radio signals in the same space, the signals
have to be separated somehow.
c@Irek Defée
MULTIMEDIA SYSTEMS
Signal Separation
• Narrowband technologies
– one transmitter uses one frequency
– receiver tunes into correct frequency
• Wideband technologies
– more advanced
– use spread spectrum technology
• There are two common types of spread spectrum
technologies
– FHSS : Frequency Hopping Spread Spectrum
– DSSS : Direct Sequence Spread Spectrum
c@Irek Defée
MULTIMEDIA SYSTEMS
Frequency Hopping Spread Spectrum
• FHSS uses narrowband
carrier
– Carrier changes frequency
between time slices
• The receiver must know the
pattern according to which
the frequency is changing
• To an unintended receiver
the signal appears to be
short duration impulse
noise
c@Irek Defée
MULTIMEDIA SYSTEMS
F
r
e
q
u
e
n
c
y
80
60
40
20
10
1
2
3
Time
4
5
Direct Sequence Spread Spectrum
• DSSS generates a redundant bit
pattern for each bit to be
transmitted
• The longer the pattern,
– the greater the probability that the
original signal can be recovered
– the more bandwidth is required
• To and unintended receiver
DSSS appears as low-power
wideband noise
c@Irek Defée
MULTIMEDIA SYSTEMS
One
Zero
RF Ad-Hoc Network Characteristics
•
•
•
•
Easy to install & configure compared to wired networks
Freedom to move the transmitter and receiver
Carrier signal typically 2.4 GHz (or 5 GHz)
Transmitter coverage typically 10 ... 100 m
– Depends on transmitter power, receiver design and propagation
path
• Data rates 1 ...10 Mbps
– Depends on number of users in the same space, interference from
other sources and propagation factors
• Security is provided with data encryption
– Eavesdropping easier than in wired networks
• Battery life limits use
• Safety of radio waves
– Transmitter power is small compared to cellular phones
c@Irek Defée
MULTIMEDIA SYSTEMS
Bluetooth
• A specification for short-range RF communication
– communication between portable devices
– communication between computer and peripherals
• Bluetooth chip characteristics:
– small size
– low power consumption
• Developed in 1994 by Ericsson
• 1997: Bluetooth SIG (Special Interest Group)
– Original SIG: Ericsson, Nokia, IBM, Toshiba, Intel
– Currently over 1600 members in the SIG
• Before manufacturers can market their device as Bluetooth
device, it must be approved by the SIG.
c@Irek Defée
MULTIMEDIA SYSTEMS
Who Is Bluetooth?
Harald Blaatand “Bluetooth” II,
King of Denmark 940-981
Son of Gorm the Old (King of Denmark)
and Thyra Danebod
(daughter of King Ethelred of England)
This is one of two Runic stones
erected in his capitol city
of Jelling (central Jutland)
This is the front of the stone
depicting the chivalry of Harald
The stone’s inscription (“runes”) say:
Harald christianized the Danes
Harald controlled Denmark
and Norway
Harald thinks notebooks and
cellular phones should
seamlessly communicate
What Does Bluetooth Do?
Landline
Cable
Replacement
Data/Voice
Access
Points
Personal Ad Hoc
Networks
Bluetooth - Technology
• Operates on 2,4 GHz ISM band
– also microwave ovens, WLAN systems, baby monitors, garage
door openers and cordless phones use this band
• Normal coverage 10 m (1mW)
– also 100 m possible (but conflicts with Bluetooth principle)
• Uses FHSS
– band 2,400 ... 2,500 GHz is divided into 79 subbands (1MHz each)
(in some countries only 23 subbands)
– transmission further divided into time slots (625 s)
– clocks synchronised to master’s clock
– 1 packet/slot, after that changes to new frequency
– 1600 hops/sec
• fast hopping, short packets  more reliable transmission (re-sending
of one corrupted packet is not a demanding task)
c@Irek Defée
MULTIMEDIA SYSTEMS
Radio Protocol
Frame
fk
Master
fk+1
One
Slot
Packet
625 us
One Slot
fk
Master
One
Slot
Packet
Slave
•
Frame
fk+1
Three Slot Packet
One
Slot
Packet
Slave
625 us
One Slot
Spread spectrum frequency hopping radio
– 79/23 one MHz channels
– Hops every packet
• Packets are 1, 3 or 5 slots long
– Frame consists of two packets
• Transmit followed by receive
– Nominally hops at 1600 times a second (one slot packets)
Bluetooth - Data and Voice
• Data & voice set different requirements for transmission
• Data: speed & reliability (even one bit can’t change)
• Voice: stream of packets must not be interrupted
– speed & reliability not so important
• To fulfill both requirements, Bluetooth uses ideas of both
packet and circuit switched connection
• Voice: SCO (Synchronous Connection Oriented)
– time slots are reserved for the stream (  steady stream)
– possible because only one device can transmit at a time & master
can reserve time slots (max speed 64 kbps)
• Data: ACL (Asynchronous Connectionless)
– can be symmetric or asymmetric (432,6 kbps ; 721 kbps / 57,6
kbps respectively)
c@Irek Defée
MULTIMEDIA SYSTEMS
Bluetooth - Piconets and Scatternets
• Bluetooth supports point-to-point and point-to-multipoint
data and voice communication
• Communicating devices (max 8) form a PICONET
• Master can be any of the devices
– clock, frequency hopping pattern
• Devices can freely join and leave a piconet
• Each device can simultaneously belong to several piconets
• Combination of several piconets = SCATTERNET
– each piconet has its own master & hopping pattern
– piconets in a scatternet are not synchronized  collisions are rare,
piconets can maintain good performance
• Piconets are small (not meant to replace WLAN)
c@Irek Defée
MULTIMEDIA SYSTEMS
The Piconet
IDa
IDd
IDa
IDd
IDa
D
A
P
M
IDe
IDe
sb
E
IDa
IDb
B
IDb
IDc
IDa
S
IDc
C
S
• All devices in a piconet hop together
–
In forming 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)
IDa
sb
M
P
or
S
Network Topology
• Radio Designation
– Connected radios can be master or
slave
– Radios are symmetric
(same radio can be
master or slave)
• Piconet
– Master can connect to seven
simultaneous or 200+ active slaves
per piconet
– Each piconet has maximum
capacity (1 MSPS)
• Unique hopping pattern/ID
• Scatternet
– High capacity system
• Minimal impact with up to 10
piconets within range
– Radios can share piconets!
S
P
M
sb
M
P
S
P
sb
S
S
Bluetooth Baseband Protocol
• There are altogether 7 states a
Bluetooth device can have:
• Standby: Waiting to join a piconet
• Inquire: Ask about radios to connect to
• Page: Connect to a specific radio
• Connected: Actively on a piconet
(master or slave)
• PARK / HOLD: Low power connected
states
Standby
Inquiry
Page
Transmit
Connected
Park
Hold
• In hold/park state modes the device consumes only 60 microAmperes.
In active data mode 5mA and in active voice mode 8-30 mA.
• The device can start participating from park/hold modes within 2 ms.
• There can be more than 200 devices that are in park/hold modes
connected to master.
c@Irek Defée
MULTIMEDIA SYSTEMS
Functional Overview
• Standby
–
Waiting to join a piconet
Unconnected
Standby
Standby
• Inquire
–
Ask about radios
to connect to
• Page
–
Connect to a specific
radio
Ttypical=2s
Connecting
States
Actively on a piconet
(master or slave)
Active
States
• Park/Hold
–
Page
Ttypical=0.6s
• Connected
–
Inquiry
Transmit
data
AMA
Connected
AMA
Ttypical=2 ms
Low Power connected
states
Low Power
States
Releases
AMA
Address
PARK
PMA
Ttypical=2 ms
HOLD
AMA
Bluetooth Architecture
•
•
•
•
•
•
•
RF: Radio transmitter/receiver,
frequency hopping
BASEBAND: Piconet and channel
definition, low-level packet definition
LINK MANAGER: Defines encryption,
authentication, SCO mode, low-power
mode
L2CAP: Link Layer Control And
Adaptation defines a simple data link
protocol on top of baseband
CONTROL: Host Controller Interface
provides a common interface between
the Bluetooth host and a Bluetooth
module (e.g., USB, UART, RS232).
Applications
TCP / IP,
WAP,SDP,
RFCOMM
etc.
Audio
L2CAP
C
O
N
T
R
O
L
Link Manager
Baseband
RF
Protocol stack, which includes plenty of protocols, e.g., RFCOMM (Radio
Frequency COM port), SDP (Service Discovery Protocol), TCP/IP and WAP.
The applications sit on top of the protocol stack.
c@Irek Defée
MULTIMEDIA SYSTEMS
What Is Bluetooth?
Applications
TCP/IP HID
RFCOMM
Application Framework
and Support
Data
Host Controller Interface
L2CAP
Audio
Link Manager
LMP
Baseband
RF
• A hardware description
• An application framework
Link Manager and
L2CAP
Radio & Baseband
Bluetooth - Error Correction
• Bluetooth uses three different error correction schemes:
FEC, ARQ and CSVD
• FEC (Forward Error Correction Code)
–
–
–
–
corrects the errors
purpose: reduce number of retransmissions
always used for packet headers
is effective, but in good conditions adds unnecessary overhead to
packets
• ARQ (Automatic Repeat Request)
– If checksum of bits does not match, packet is retransmitted
– Good in good conditions : seldom need for retransmitting
• CSVD (Continuous Variable Slope Delta Modulation)
– used when transmitting sound, because retransmitting of packets is
not sensible
– With help of CSVD speech is understandable even if 4% of
packets are corrupted
c@Irek Defée
MULTIMEDIA SYSTEMS
Bluetooth - Security
• Bluetooth hardware supports
– user authentication (one-way / two-way / no authentication)
– data encryption (secret key length 0 ; 40 or 64 bits)
– session key generation
• Three entities are used in the security algorithms:
– Bluetooth unit address (public entity)
– Private user key (secret entity)
– Random number (different for each new transaction)
• Users who need stronger protection can use upper layers of
Bluetooth stack to do this (network transport protocol /
application programs)
c@Irek Defée
MULTIMEDIA SYSTEMS
Bluetooth - Software
•
•
•
•
Piconets are controlled by software
Software can reside in any of the participating devices
Lot of software is needed to build sensible applications
Applications can use existing protocols like TCP/IP, WAP,
RFCOMM, OBEX ...
• E.g. Java-based JINI architecture by Sun Microsystems
can handle the communication between participants in an
ad-hoc network.
c@Irek Defée
MULTIMEDIA SYSTEMS
BLUETOOTH APPLICATIONS
• PARK RIDGE, Ill. — Motorola Inc. will take Bluetooth a
step closer to the automobile this week, as it demonstrates
a new in-car communication system at the Convergence
2000 show in Detroit.
• The demonstration, which involves moving data back and
forth from consumer devices to automotive network buses,
is believed to be the first of its kind in the automotive
industry. It's also one that has been anxiously awaited by
automotive engineers, many of whom foresee a vast array
of potential applications for Bluetooth's wireless
techniques.
c@Irek Defée
MULTIMEDIA SYSTEMS
BLUETOOTH APPLICATIONS
c@Irek Defée
MULTIMEDIA SYSTEMS
BLUETOOTH APPLICATIONS
c@Irek Defée
MULTIMEDIA SYSTEMS
BLUETOOTH APPLICATIONS
c@Irek Defée
MULTIMEDIA SYSTEMS
BLUETOOTH APPLICATIONS
PAYING FOR TICKETS AND ACCESS IN TRAIN STATION
c@Irek Defée
MULTIMEDIA SYSTEMS
BLUETOOTH APPLICATIONS
c@Irek Defée
MULTIMEDIA SYSTEMS
Conclusions for this lecture:
 THERE IS VERY WIDE RANGE OF
WIRELESS NETWORK SYSTEMS
 SOME OF THEM WILL HAVE HIGH
BANDWIDTH, ALL WILL PROVIDE
MULTIMEDIA CAPABILTIES
 TERMINALS WILL BECOME
MULTIMODAL AND MULTISYSTEM
GPRS+HSCSD+ EDGE + 3G UMTS + HSD
+WLAN+WiMAX + digital TV BROADCAST
+ BLUETOOTH….
c@Irek Defée
MULTIMEDIA SYSTEMS