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ECEN4533 Data Communications Lecture #42 22 April 2013 Dr. George Scheets

ECEN4533 Data Communications Lecture #42 22 April 2013 Dr. George Scheets. Problems : 2012 Final Exam Final Exam 0800 – 0950, Friday, 3 May (Live) On or before Friday, 10 May (DL) Wireshark Project due by midnight 4 May (All) Late turn in NOT accepted

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ECEN4533 Data Communications Lecture #42 22 April 2013 Dr. George Scheets

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  1. ECEN4533 Data CommunicationsLecture #42 22 April 2013Dr. George Scheets • Problems: 2012 Final Exam • Final Exam • 0800 – 0950, Friday, 3 May (Live) • On or before Friday, 10 May (DL) • Wireshark Project due by midnight 4 May (All) • Late turn in NOT accepted • 15 points + 20 points extra credit • Quiz 2 Results • Hi = 18.7, Low = 12.2, Ave = 16.82, σ = 2.70

  2. ECEN4533 Data CommunicationsLecture #43 24 April 2013Dr. George Scheets • Problems: 17-12, 17, & 18 • Final Exam • 0800 – 0950, Friday, 3 May (Live) • On or before Friday, 10 May (DL) • Wireshark Project due by midnight 4 May (All) • Late turn in NOT accepted • 15 points + 20 points extra credit

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

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

  5. Video 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 AMP ... AMP Headend ... 2nd Generation Hybrid Fiber Coax FTT curb AMP ... Copper Coax Fiber

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

  7. Cable Networks • Have a Lot of BW (XXX MHz) • Allocate 6 MHz channels for various services • FDM • 6 MHz Channel can carry • 2 MPEG4 HDTV signals • 2-6 MPEG2/4 SDTV signals • 30-40 Mbps Cable Modem Traffic (Shared)DOCSIS (Data over Cable Service Interface Specification) • Internet • VoIP

  8. Last 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 ...

  9. ADSL • Plain Vanilla ADSL • 384 Kbps - 8 Mbps downstream • 16 Kbps - 640 Kbps upstream • Uses FDM • POTS analog voice stays in 0 - 4 KHz band • Upstream and Downstream signals mappedto higher frequency bands • Uses OFDM • ATM or Ethernet frame formats

  10. Different channels use some of the bandwidth all of the time. FDM FDMAWDM frequency 1 2 3 4 5 time

  11. Orthogonal FDM frequency Channel 1 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 time

  12. 802.11 & Cellular SystemsWays to decrease P(Bit Error) • Crank up power out • As a last resort (cellular) • Reduce noise in system • Slow down transmitted bit rate • Use directional antennas • Use Forward Error Correcting codes • Use Orthogonal Frequency Division Multiplexing

  13. FDM with Multi-path T3 bounce path time XMTR direct path direct path pulses RCVR bounce path pulses delay Signal sum seen by Receiver Symbol decision intervals at Receiver. The third bit is obliterated by multi-path. T1 T2 T3

  14. OFDM with Multi-path Slower symbol rate over each subchannel. delay bounce direct bounce direct direct bounce Matched filter detector will work OK. T1 T2 T3

  15. Some of the Flavored Versions • ADSL2 • Needs higher SNR than ADSL • 8 -12 Mbps downstream • 800 Kbps - 3.5 Mbps upstream • ADSL2+ • Doubles used Bandwidth & Bit Rates • Can also bond multiple twisted pairsInverse Multiplex • VDSL2 • 4 - 8 MHz BW, Inverse Multiplexing • 100 Mbps over short distances

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

  17. DSL Speeds (Copper) source: www.convergedigest.com/blueprints/ttp03/bp1.asp?ID=232&ctgy=Loop

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

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

  20. 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. IPTV on the Access Network ISP Backbone Regional Cache ... Local Cache ... User TV User TV User TV User TV

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

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

  23. 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... IPTV on the Access Network ISP Backbone Regional Cache ... Local Cache ... User TV User TV User TV User TV

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

  25. HDTV Video On Demand • Roughly 80 TV's per 100 U.S. Population • Current population about 314,900,000 • About 251.9 million TV's • Worst Case Traffic Demand251,900,000 x 9.51 Mbps/user = 2,395,569,000,000,000 bps • All aren't HDTV capable • All won't be on • Should be some multicasting • etc.

  26. Video On Demand- Reservations I want to watch "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 3 Separate Streams Required to service 3 users. Router Sink Sink Sink

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

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