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.