Download - Lecture slides, updated 16.04.2009
c@Irek Defée MULTIMEDIA SYSTEMS
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
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• 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
. PHASE OF THE SIGNAL IS CHANGED (HERE FOUR VALUES ARE USED)
00
01
1110
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• PHASE AND AMPLITUDE CAN BE
CHANGED – QAM
HERE WE CAN ASSIGN3 BITS TO EACH VALUEOF AMPLITUDE AND PHASE
000
THE MORE AMPLITUDE AND PHASE VALUES THE MOREINFORMATION CAN BE SEND, BUT SIGNAL IS MORE SENSITIVE TO NOISE
c@Irek Defée MULTIMEDIA SYSTEMS
16-QAM BIT ASSIGNMENT
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• 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
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• 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
USERS (100-200 PER HEADEND)
DISTRIBUTION (FIBER OPTICS)
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
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WIRLESS SYSTEMS
CELLULAR NETWORKS
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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 Accessto the reception and systems are called CDMA, FDMA,...
c@Irek Defée MULTIMEDIA SYSTEMS
THESE ACCESS SYSTEMS CAN BE USED IN ALL KINDOF 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
TRANSMITTERIN THE CENTEROF EACH CELL
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• 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
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- IN ADDITION GSM THE SYSTEM HAS ALSO A KIND OF CDMA – FREQUENCY HOPPING:FREQUENCY BAND CAN BE CHANGED FROMTIME SLOT TO TIME SLOT ACCORDING TOSPECIFIC 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). MINIMUMCELL SIZE IS 100-500M(?). SO WE CAN GETHIGH 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
144 kbps 144 kbpsISDN
Standards Implementation
2048 kbps 384 kbpsWCDMA
Maximum Data Rate for New Systems
470 kbps < 470 kbpsEDGE
171 kbps 57.6 kbpsGPRS
57.6 kbps 28.8 kbpsHSCSD
9.6 kbps 9.6 kbpsGSM Data
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
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GPRS PACKETS ALLOCATION
Radio resources allocation– either to Circuit Switched service– or to Packet Switched service
Priority can be given to one service while ensuring minimum capacity for the other one
TDMA frame
TRX : GPRS & GSM
0 7TS number
GPRS onlyGSM only GSM or GPRS
c@Irek Defée MULTIMEDIA SYSTEMS
Coding schemes in GPRS• 4 coding schemes for packet transfers
thus data rates increase
CS
information protection
data rates (Kbits/s)
CS4 : no protection21.4
CS1 : same as GSM measurements reporting
13.4
15.6
9. 05
CS2 CS3
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GPRS coverage• New design thresholds
– depending on coding scheme– due to decreasing protection / interferences
• On existing networks– "concentric" GPRS coverage
GSM only cellenabling
GPRSGSM
coverage
CS1
CS2
CS3CS4
c@Irek Defée MULTIMEDIA SYSTEMS
Coverage of GPRS
GSM Voice (1)
CS1 (1.06)
CS2 (0.82)
CS3 (0.72)
CS4 (0.42)
Base Station
There is no significant change in coverage from GSM to GPRS CS1 and CS2There is no significant change in coverage from GSM to GPRS CS1 and CS2
Cell Radius
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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
BTSMSC/VLR
SGSN GGSN
BSC
PCU
GMSC
GPRS BackboneIP Network
BG CG DNS
BG = Border GatewayCG = Charging GatewayDNS = Domain Name SystemsPCU = Packet Control UnitSGSN = Serving GPRS Support NodeGGSN = Gateway GPRS Support NodeBTS = Base Transceiver StationBSC = Base Station ControllerMSC = Mobile Services Switching CentreGMSC = Gateway MSC
HLR
New GPRS Network Elements
Existing Elements
New Elements
c@Irek Defée MULTIMEDIA SYSTEMS
ApplicationApplication
IP / X.25IP / X.25
SNDCPSNDCP
LLCLLC
RLCRLC
MACMAC
GSM PLGSM PL
SNDCPSNDCP
BSSGPBSSGP
L1bisL1bis
RLCRLC
MACMAC
GSM PLGSM PL
LLC RelayLLC Relay
L2L2
L1L1
L2L2
L1L1
IPIP
GTPGTP
IP / X.25IP / X.25
UmUm GbGb GnGn GiGiMSMS BSSBSS SGSNSGSN GGSNGGSN
FrameFrameRelayRelay
FrameFrameRelayRelay
BSSGPBSSGP
L1bisL1bis
LLCLLC
GTPGTP
IPIP
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.
THE GPRS TRANSPORT PLANE
TLLITLLI
TIDTID
IPIP
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X25 end to end
GGSNSGSN
GPRS IP backbone
GTP tunnel layerLLC tunnel layer
IP end to end
RADIO specificL2
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)
3 layer stack
THE THREE LAYER TRANSPORT PLANE IN 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
up- / downlink 100% coverage 95% coverage 100% coverage 95% coverage1 + 1 9.6 14.4 9.6 13.22 + 2 19.2 28.8 19.2 26.41 + 3 --- ---- 28.8 39.61 + 4 --- ---- 38.4 53.8
HSCSD User Data Ratetransparent service non transparent service
GPRS User Data Rate
Coding # of timeslotsScheme 1 2 3 4 5 6 7 8
CS-1 9,05 18,1 27,15 36,2 45,25 54,3 63,35 72,4CS-2 13,4 26,8 40,2 53,6 67 80,4 93,8 107,2CS-3 15,6 31,2 46,8 62,4 78 93,6 109,2 124,8CS-4 21,4 42,8 64,2 85,6 107 128,4 149,8 171,2
c@Irek Defée MULTIMEDIA SYSTEMS
GSM Wireless Data Development Steps
High Speed Data CircuitsHSCSD n*14.4 (3*14.4 = 43.2)
High Speed Packet CapabilitiesGPRS (e.g. 3* 13.4 = 40.2)
3Q 1999
3Q 2000
c@Irek Defée MULTIMEDIA SYSTEMS
High Speed data circuitsHSCSD n*14.4 (3*14.4 = 43.2)
MSCBSC
BTS
BTS
UDIISDN
GSM
IWE
PSTN
Internet
CorporateNetworks
LAN
c@Irek Defée MULTIMEDIA SYSTEMS
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: Pros and Cons
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
MSCBSS
BTSGSM
HLR
GPRS backboneFR / ATM
GGSN
GGSN
GGSN
SGSN Border GW
CorporateNetworks
otherPLMN
Internet
High Speed Packet CapabilitiesGPRS (e.g. 3* 13.4 = 40.2)
c@Irek Defée MULTIMEDIA SYSTEMS
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.
GPRS: Pros and Cons
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
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SmartMessaging
BankingTraffic info & guidanceNewsWeatherTicket orderingInfo- & Entertainment-ServicesFleet management
HSCSD
File transferCorporate access / tele workingOnline e-mailReal-time applicationsE-cash & paymentsAudio & video on demandVideo surveillance services(e.g. taxi, money transport)Remote healthcare
GPRS
InternetIntranetE-mailScheduler AccessRemote controlMonitoring
WAP / WMLHTTP / HTML
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APPLICATION AREAS
Business Private
• Intranet access• Tele working• Online e-mail / fax
• Websurfing• Electronic payment
services• Mobile banking
With focus on• Reliability• Sufficient data rates• Ease of Use
With focus on• Price• Price• Price
Best addressed by
HSCSDHSCSD
Best addressed by
GPRSGPRS
c@Irek Defée 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
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What is UMTS? Called popularly 3G
•Universal Mobile Telecommunications Service
•Member of IMT-2000 family
•Global multimedia
•Replacement (complement) for GSM
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Spectrum allocation for UMTS
• 2x60MHz paired spectrum + 20 MHz and 15 MHz unpaired = 155 MHz
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UTRA Key Parameters
FDD TDD
Multiple access scheme W-CDMA TD-CDMA
Carrier spacing 4·4 – 5·2 MHz 5 MHz
Chip rate 3·84 Mchip/s (Mcps)
Spreading factor range 4–512 1–16
Modulation QPSK
Pulse shaping root raised cosine, roll-off = 0·22
Frame length 10 ms
Timeslots per frame 15
UTRA – UMTS TERRESTRIAL RADIO ACCESS
c@Irek Defée 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 ratesCategory Max. number of
HS-DSCH codesModulation 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 range1-2 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
1 2 3 4 5
Frequency
80
60
40
20
10
Time
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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
One
Zero
c@Irek Defée MULTIMEDIA SYSTEMS
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.
Who Is Bluetooth?Harald Blaatand “Bluetooth” II,
King of Denmark 940-981Son of Gorm the Old (King of Denmark)
and Thyra Danebod (daughter of King Ethelred of England)
This is one of two Runic stones This is one of two Runic stones erected in his capitol city erected in his capitol city of Jelling (central Jutland)of Jelling (central Jutland)This is the front of the stone This is the front of the stone
depicting the chivalry of Haralddepicting the chivalry of HaraldThe stone’s inscription (“runes”) say:The stone’s inscription (“runes”) say:
Harald christianized the DanesHarald christianized the DanesHarald controlled Denmark Harald controlled Denmark
and Norwayand NorwayHarald thinks notebooks and Harald thinks notebooks and
cellular phones should cellular phones should seamlessly communicateseamlessly communicate
Personal Ad Hoc Personal Ad Hoc NetworksNetworks
Cable Cable ReplacementReplacement
LandlineLandline
Data/Voice Data/Voice Access Access PointsPoints
What Does Bluetooth Do?
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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)
O neSlot
Packet
Three S lot Packet
Fram e
M aster
S lave
625 usO ne S lo t
fk fk+1
O neSlot
Packet
Fram e
M aster
S lave
625 usO ne S lo t
fk fk+1
O neSlot
Packet
Radio Protocol
• 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)
c@Irek Defée MULTIMEDIA SYSTEMS
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)
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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)
A
D
C
B
E
ID b
ID a
ID c
ID d
ID e
M
P
S
S
sb
ID a
ID c
ID d
ID a
IDa
IDa
ID e
ID b
The Piconet
• 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)
ID a
P
M Soror
sb
MM
S
S S
S
P
sb
sb
P
P
Network Topology• Radio Designation
– Connected radios can be master or slave
– Radios are symmetric (same radio can bemaster 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!
c@Irek Defée MULTIMEDIA SYSTEMS
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
• 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.
Standby
Inquiry Page
Transmit Connected
Park Hold
InquiryInquiry PagePage
ConnectedConnectedAMAAMA
TransmitTransmitdatadataAMAAMA
TTtypical=0.6stypical=0.6s
TTtypical=2stypical=2s
HOLDHOLDAMAAMA
PARKPARKPMAPMA
TTtypical=2 mstypical=2 ms TTtypical=2 mstypical=2 ms
ReleasesReleasesAMAAMA
AddressAddressLow PowerLow Power
StatesStates
ActiveActiveStatesStates
StandbyStandby
ConnectingConnectingStatesStates
UnconnectedUnconnectedStandbyStandby
Det
ach
Det
ach
Functional Overview• 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
c@Irek Defée MULTIMEDIA SYSTEMS
Bluetooth Architecture
• 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.
RF
Baseband
Link Manager
L2CAPAudio
TCP / IP,WAP,SDP,RFCOMMetc.
CONTROL
Applications• 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).
Application Framework Application Framework and Supportand Support
Link Manager and Link Manager and L2CAPL2CAP
Radio & BasebandRadio & Baseband
Host Controller Host Controller InterfaceInterface
RFRF
BasebandBaseband
AudioAudioLink ManagerLink Manager LMPLMPL2CAPL2CAP
TCP/IPTCP/IP HIDHID RFCOMMRFCOMM
ApplicationsApplications
DataDataC
ontr
ol
Con
trol
What Is Bluetooth?
• A hardware description• An application framework
c@Irek Defée MULTIMEDIA SYSTEMS
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
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BLUETOOTH APPLICATIONS
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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….