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ECEN4533 Data Communications Lecture #4222 April 2013 Dr. George Scheets n Problems: 2012 Final Exam n Final Exam u 0800 – 0950, Friday, 3 May (Live) u.

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Presentation on theme: "ECEN4533 Data Communications Lecture #4222 April 2013 Dr. George Scheets n Problems: 2012 Final Exam n Final Exam u 0800 – 0950, Friday, 3 May (Live) u."— Presentation transcript:

1 ECEN4533 Data Communications Lecture #4222 April 2013 Dr. George Scheets n Problems: 2012 Final Exam n Final Exam u 0800 – 0950, Friday, 3 May (Live) u On or before Friday, 10 May (DL) n Wireshark Project due by midnight 4 May (All) u Late turn in NOT accepted u 15 points + 20 points extra credit n Quiz 2 Results u Hi = 18.7, Low = 12.2, Ave = 16.82, σ = 2.70

2 ECEN4533 Data Communications Lecture #4324 April 2013 Dr. George Scheets n Problems: 17-12, 17, & 18 n Final Exam u 0800 – 0950, Friday, 3 May (Live) u On or before Friday, 10 May (DL) n Wireshark Project due by midnight 4 May (All) u Late turn in NOT accepted u 15 points + 20 points extra credit

3 Video Delivery Systems n n Cable TV u u Tree configuration u u Distribution systems originally all coax u u Originally Analog NTSC u u BW 700 MHz Headend AMP... AMP... Initially Simplex Copper Coax

4 Video Delivery Systems n n Cable TV u u Tree configuration u u Distribution systems originally all coax u u Fiber deployed from Head End side moving out Headend AMP... AMP... Copper Coax Fiber 2nd Generation Hybrid Fiber Coax a.k.a. FTTx

5 Video Delivery Systems n n Cable TV u u Now mostly digital ATSC, MPEG2/4 F F Analog NTSC now uncommon u u Cable Modems require 2-way commo F F Some 6 MHz channels pulled from TV pool Headend AMP... AMP... Copper Coax Fiber 2nd Generation Hybrid Fiber Coax FTT curb

6 Video Delivery Systems n n Cable TV u u Ultimate Goal: Fiber to the Home (FTTH) u u Passive Optical Network F F No active electronics in access network Headend Splitter... Fiber 3rd Generation FTT home... Splitter... Splitter

7 Cable Networks n Have a Lot of BW (XXX MHz) n Allocate 6 MHz channels for various services u FDM n 6 MHz Channel can carry u 2 MPEG4 HDTV signals u 2-6 MPEG2/4 SDTV signals u Mbps Cable Modem Traffic (Shared) DOCSIS (Data over Cable Service Interface Specification) F Internet F VoIP

8 Last Mile Options n n Digital Subscriber Line (xDSL) u u Rides on top of Telco access network u u Runs over twisted pair cabling (BW X to XX MHz) u u Various flavors exist CO...

9 ADSL n Plain Vanilla ADSL u 384 Kbps - 8 Mbps downstream u 16 Kbps Kbps upstream n Uses FDM u POTS analog voice stays in KHz band u Upstream and Downstream signals mapped to higher frequency bands F Uses OFDM u ATM or Ethernet frame formats

10 FDM FDMA WDM frequency time Different channels use some of the bandwidth all of the time

11 Orthogonal FDM frequency time Channels split into sub-channels Bits parceled out to sub-channels Advantage: Sub-channel bit rates can be modified to cope with interference Less susceptible to multipath Channel 1

12 & Cellular Systems Ways to decrease P(Bit Error) n Crank up power out u As a last resort (cellular) n Reduce noise in system n Slow down transmitted bit rate n Use directional antennas n Use Forward Error Correcting codes n Use Orthogonal Frequency Division Multiplexing

13 FDM with Multi-path XMTR RCVR direct path bounce path direct path pulses bounce path pulses Signal sum seen by Receiver T1T2T3 Symbol decision intervals at Receiver. The third bit is obliterated by multi-path. T3 time delay

14 OFDM with Multi-path direct T3 bounce direct bounce direct bounce T2T1 Matched filter detector will work OK. delay Slower symbol rate over each subchannel.

15 Some of the Flavored Versions n ADSL2 u Needs higher SNR than ADSL u Mbps downstream u 800 Kbps Mbps upstream n ADSL2+ u Doubles used Bandwidth & Bit Rates u Can also bond multiple twisted pairs Inverse Multiplex n VDSL2 u MHz BW, Inverse Multiplexing u 100 Mbps over short distances

16 xDSL n ADSL (< 8 Mbps downstream) can carry u A handful of 1.5 Mbps SDTV signals u Internet traffic (in left over BW) & Standard voice call u 0 HDTV signals n ADSL2+ (< Mbps down stream) can carry u Two 9 Mbps MPEG4 u Internet traffic (in left over BW) & Standard voice call n To Support Triple Play Service u TelCo's need to drive fiber down towards homes u FTTH: Gbps speeds possible u VDSL2+ can support 100 Mbps on copper out to 0.5 Km Longer reach if FTTC in place

17 DSL Speeds source: (Copper)

18 IPTV & Last Mile Networks n On the Access Network u Cable TV/Cable Modem: No Problem u FTTH : No Problem u xDSL: Problem F Unless Next Door to CO F Or near FTTC termination F Either way, can't stream 150 HDTV channels F Solution: Selectively feed a few n On the Home Network u 100 Mbps can handle several HDTV channels u Leaves significant BW available for data & yet-to-be-invented apps

19 Powerline HAN 10/100BaseT Ethernet: PC Adapter 500 Mbps: Adapter Adapter

20 IPTV on the Access Network ISP Backbone User TV User TV User TV User TV Local Cache... n n Regional Caches u u Streamed All or Most TV Network Programs n n Local Cache u u House Apartment Complex u u Streamed > 1 channel, Access BW permitting. n n User TV u u Streamed > 1 channel, Home BW permitting. Regional Cache...

21 IPTV on the Access Network ISP Backbone User TV User TV User TV User TV Local Cache... n n Want to change channel? n n TV Cache Checked u u Available? < 1/2 second to change u u Not available? Packet request shipped to Local Cache Regional Cache...

22 IPTV on the Access Network ISP Backbone User TV User TV User TV User TV Local Cache... n n Local Cache Checked u u Available? Channel streamed to TV May take > 1/2 second u u Not available? Packet request shipped to Regional Cache Regional Cache...

23 IPTV on the Access Network ISP Backbone User TV User TV User TV User TV Local Cache... n n Regional Cache Checked u u Available? Channel streamed to Local Cache, then user TV. u u Not available? Packet request might need to be shipped to info source. u u If these are busy... Regional Cache...

24 IPTV on the Access Network ISP Backbone User TV User TV User TV User TV Local Cache... n n Channel Change May Take Several Seconds n n Channel Surfers Won't be Happy n n Ongoing Research u u Streaming Techniques to minimize channel change time. u u Predicting next channel Regional Cache... When they're awake.

25 HDTV Video On Demand n Roughly 80 TV's per 100 U.S. Population n Current population about 314,900,000 n About million TV's n Worst Case Traffic Demand 251,900,000 x 9.51 Mbps/user = 2,395,569,000,000,000 bps u All aren't HDTV capable u All won't be on u Should be some multicasting u etc.

26 Video On Demand- Reservations I want to watch "Dr. Strangelove"Dr. Strangelove at 7:12 pm. Someone else in vicinity commenced watching 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.

27 Unicast Server Router Sink 3 Separate Streams Required to service 3 users.

28 Multicast Server Router Sink For a portion of the route, 1 stream suffices.

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