ECEN4533 Data Communications Lecture #4222 April 2013 Dr. George Scheets n Problems: 2012 Final Exam...
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Transcript of ECEN4533 Data Communications Lecture #4222 April 2013 Dr. George Scheets n Problems: 2012 Final Exam...
ECEN4533 Data CommunicationsLecture #42 22 April 2013Dr. George Scheets
ECEN4533 Data CommunicationsLecture #42 22 April 2013Dr. George Scheets Problems: 2012 Final ExamProblems: 2012 Final Exam Final ExamFinal Exam
0800 – 0950, Friday, 3 May (Live)0800 – 0950, Friday, 3 May (Live) On or before Friday, 10 May (DL)On or before Friday, 10 May (DL)
Wireshark Project due by midnight 4 May (All)Wireshark Project due by midnight 4 May (All) Late turn in NOT acceptedLate turn in NOT accepted 15 points + 20 points extra credit15 points + 20 points extra credit
Quiz 2 ResultsQuiz 2 Results Hi = 18.7, Low = 12.2, Ave = 16.82, Hi = 18.7, Low = 12.2, Ave = 16.82, σσ = 2.70 = 2.70
ECEN4533 Data CommunicationsLecture #43 24 April 2013Dr. George Scheets
ECEN4533 Data CommunicationsLecture #43 24 April 2013Dr. George Scheets
Problems: 17-12, 17, & 18Problems: 17-12, 17, & 18 Final ExamFinal Exam
0800 – 0950, Friday, 3 May (Live)0800 – 0950, Friday, 3 May (Live) On or before Friday, 10 May (DL)On or before Friday, 10 May (DL)
Wireshark Project due by midnight 4 May (All)Wireshark Project due by midnight 4 May (All) Late turn in NOT acceptedLate turn in NOT accepted 15 points + 20 points extra credit15 points + 20 points extra credit
Video Delivery SystemsVideo Delivery Systems Cable TV
Tree configuration Distribution systems originally all coax Originally Analog NTSC BW ≈ 700 MHz
HeadendAMP
AMP
...
...
AMP ...Initially Simplex Copper Coax
Video Delivery SystemsVideo Delivery Systems Cable TV
Tree configuration Distribution systems originally all coax Fiber deployed from Head End side moving
out
HeadendAMP
AMP
...
...
AMP ...
Copper CoaxFiber
2nd GenerationHybrid Fiber Coax
a.k.a. FTTx
Video Delivery SystemsVideo Delivery Systems Cable TV
Now mostly digital ATSC, MPEG2/4 Analog NTSC now uncommon
Cable Modems require 2-way commo Some 6 MHz channels pulled from TV pool
HeadendAMP
AMP
...
...
AMP ...
Copper CoaxFiber
2nd GenerationHybrid Fiber Coax
FTT curb
Video Delivery SystemsVideo Delivery Systems Cable TV
Ultimate Goal: Fiber to the Home (FTTH) Passive Optical Network
No active electronics in access network
Headend Splitter
...Fiber
3rd GenerationFTT home
...Splitter
...Splitter
Cable NetworksCable Networks Have a Lot of BW (XXX MHz)Have a Lot of BW (XXX MHz) Allocate 6 MHz channels for various servicesAllocate 6 MHz channels for various services
FDMFDM 6 MHz Channel can carry6 MHz Channel can carry
2 MPEG4 HDTV signals2 MPEG4 HDTV signals 2-6 MPEG2/4 SDTV signals2-6 MPEG2/4 SDTV signals 30-40 Mbps Cable Modem Traffic (Shared)30-40 Mbps Cable Modem Traffic (Shared)
DOCSIS (Data over Cable Service Interface Specification)DOCSIS (Data over Cable Service Interface Specification) InternetInternet VoIPVoIP
Last Mile OptionsLast Mile Options Digital Subscriber Line (xDSL)
Rides on top of Telco access network Runs over twisted pair cabling (BW X to XX MHz) Various flavors exist
CO
...
ADSLADSL Plain Vanilla ADSLPlain Vanilla ADSL
384 Kbps - 8 Mbps downstream384 Kbps - 8 Mbps downstream 16 Kbps - 640 Kbps upstream16 Kbps - 640 Kbps upstream
Uses FDMUses FDM POTS analog voice stays in 0 - 4 KHz bandPOTS analog voice stays in 0 - 4 KHz band Upstream and Downstream signals mappedUpstream and Downstream signals mapped
to higher frequency bandsto higher frequency bands Uses OFDMUses OFDM
ATM or Ethernet frame formats ATM or Ethernet frame formats
FDM FDMAWDM
FDM FDMAWDM frequency
tim
eDifferent channels use some of the bandwidth all of the time.
1 2 3 4 5
Orthogonal FDMOrthogonal FDMfrequency
tim
e
Channels split into sub-channelsBits parceled out to sub-channels
Advantage:Sub-channel bit rates can be modified to cope with interferenceLess susceptible to multipath
Channel 1
802.11 & Cellular SystemsWays to decrease P(Bit Error)
802.11 & Cellular SystemsWays to decrease P(Bit Error)
Crank up power outCrank up power out As a last resort (cellular)As a last resort (cellular)
Reduce noise in systemReduce noise in system Slow down transmitted bit rateSlow down transmitted bit rate Use directional antennasUse directional antennas Use Forward Error Correcting codesUse Forward Error Correcting codes Use Orthogonal Frequency Division MultiplexingUse Orthogonal Frequency Division Multiplexing
FDM with Multi-pathFDM with Multi-path
XMTR
RCVRdirect path
bounce path
direct path pulsesbounce path pulses
Signal sum seen by Receiver
T1 T2 T3 Symbol decision intervals at Receiver.The third bit is obliterated by multi-path.
T3time
delay
OFDM with Multi-pathOFDM with Multi-path
direct
T3
bounce
directbounce
directbounce
T2T1
Matched filter detector will work OK.
delay
Slower symbol rate over each subchannel.
Some of the Flavored VersionsSome of the Flavored Versions ADSL2ADSL2
Needs higher SNR than ADSLNeeds higher SNR than ADSL 8 -12 Mbps downstream8 -12 Mbps downstream 800 Kbps - 3.5 Mbps upstream800 Kbps - 3.5 Mbps upstream
ADSL2+ADSL2+ Doubles used Bandwidth & Bit RatesDoubles used Bandwidth & Bit Rates Can also bond multiple twisted pairsCan also bond multiple twisted pairs
Inverse MultiplexInverse Multiplex VDSL2VDSL2
4 - 8 MHz BW, Inverse Multiplexing4 - 8 MHz BW, Inverse Multiplexing 100 Mbps over short distances100 Mbps over short distances
xDSLxDSL ADSL (ADSL (<< 8 Mbps downstream) can carry 8 Mbps downstream) can carry
A handful of 1.5 Mbps SDTV signalsA handful of 1.5 Mbps SDTV signals Internet traffic (in left over BW) & Standard voice callInternet traffic (in left over BW) & Standard voice call 0 HDTV signals0 HDTV signals
ADSL2+ (ADSL2+ (<< Mbps down stream) can carry Mbps down stream) can carry Two 9 Mbps MPEG4Two 9 Mbps MPEG4 Internet traffic (in left over BW) & Standard voice callInternet traffic (in left over BW) & Standard voice call
To Support Triple Play ServiceTo Support Triple Play Service TelCo's need to drive fiber down towards homesTelCo's need to drive fiber down towards homes FTTH: Gbps speeds possibleFTTH: Gbps speeds possible VDSL2+ can support 100 Mbps on copper out to 0.5 KmVDSL2+ can support 100 Mbps on copper out to 0.5 Km
Longer reach if FTTC in placeLonger reach if FTTC in place
DSL SpeedsDSL Speeds
source: www.convergedigest.com/blueprints/ttp03/bp1.asp?ID=232&ctgy=Loop
(Copper)
IPTV & Last Mile NetworksIPTV & Last Mile Networks On the Access NetworkOn the Access Network
Cable TV/Cable Modem: No ProblemCable TV/Cable Modem: No Problem FTTH : No ProblemFTTH : No Problem xDSL: ProblemxDSL: Problem
Unless Next Door to COUnless Next Door to CO Or near FTTC terminationOr near FTTC termination Either way, can't stream 150 HDTV channelsEither way, can't stream 150 HDTV channels Solution: Selectively feed a fewSolution: Selectively feed a few
On the Home NetworkOn the Home Network 100 Mbps can handle several HDTV channels100 Mbps can handle several HDTV channels Leaves significant BW available for data & Leaves significant BW available for data &
yet-to-be-invented appsyet-to-be-invented apps
Powerline HANPowerline HAN
10/100BaseT Ethernet: PC ↔ Adapter500 Mbps: Adapter ↔ Adapter
IPTV on the Access NetworkIPTV on the Access Network
ISP Backbone
UserTVUserTV
UserTV
UserTV
LocalCache
...
Regional Caches Streamed All or Most TV
Network Programs Local Cache
HouseApartment Complex
Streamed > 1 channel, Access BW permitting.
User TV Streamed > 1 channel,
Home BW permitting.
RegionalCache
...
IPTV on the Access NetworkIPTV on the Access Network
ISP Backbone
UserTVUserTV
UserTV
UserTV
LocalCache
...
Want to change channel?
TV Cache Checked Available?
< 1/2 second to change Not available?
Packet request shipped to Local Cache
RegionalCache
...
IPTV on the Access NetworkIPTV on the Access Network
ISP Backbone
UserTVUserTV
UserTV
UserTV
LocalCache
...
Local Cache Checked Available?
Channel streamed to TVMay take > 1/2 second
Not available?Packet request shipped to Regional Cache
RegionalCache
...
IPTV on the Access NetworkIPTV on the Access Network
ISP Backbone
UserTVUserTV
UserTV
UserTV
LocalCache
...
Regional Cache Checked Available?
Channel streamed to Local Cache, then user TV.
Not available?Packet request might need to be shipped to info source.
If these are busy...
RegionalCache
...
IPTV on the Access NetworkIPTV on the Access Network
ISP Backbone
UserTVUserTV
UserTV
UserTV
LocalCache
...
Channel Change May Take Several Seconds
Channel Surfers Won't be Happy Ongoing Research
Streaming Techniques to minimize channel change time.
Predicting next channel
RegionalCache
...
When they're awake.
HDTV Video On DemandHDTV Video On Demand Roughly 80 TV's per 100 U.S. PopulationRoughly 80 TV's per 100 U.S. Population Current population about 314,900,000Current population about 314,900,000 About 251.9 million TV'sAbout 251.9 million TV's Worst Case Traffic DemandWorst Case Traffic Demand
251,900,000 x 9.51 Mbps/user =251,900,000 x 9.51 Mbps/user =2,395,569,000,000,000 bps2,395,569,000,000,000 bps
All aren't HDTV capableAll aren't HDTV capable All won't be onAll won't be on Should be some multicastingShould be some multicasting etc.etc.
Video On Demand- ReservationsVideo On Demand- ReservationsI want to watch"Dr. Strangelove"at 7:12 pm.
Someone else in vicinity commencedwatching at 6:58 pm?
Reservations 1 hour in advance required?
System can plan ahead.6:58 request could be streamed live and forwarded (multicast) to my location, stored locally, played back commencing at 7:12.
UnicastUnicast
Server
Router
SinkSinkSink
3 Separate Streams Required to service 3 users.
MulticastMulticast
Server
Router
SinkSinkSink
For a portion of the route, 1 stream suffices.