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Wireless

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Wireless

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  1. ECEN5553 Telecom SystemsDr. George ScheetsWeek 15Read [32] "The Picturephone is Here. Really."[33] "Perspective in Next-Generation Home Networks"[34a] "Is This the Moment for Broadband over Power Lines?"[34b] "Dish Network for the Enterprise"Exam #2 Final Results (90 points) Hi = 87.3, Low = 33.0, Average = 65.19 Standard Deviation = 13.83 A > 77, B > 62, C > 53, D > 44Final ExamFriday, 14 December, 1400 - 1550 (Live)Not later than 21 December (Async DL)

  2. Wireless • LAN • 802.11 WiFi • MAN • Cell Systems3GSM & CDMA2000 → LTE • Free Space Lasers • Point to Point Radio802.16 WiMax • WAN • Geosynchronous Satellites • Low Earth Orbiting Satellites

  3. MPEG 1 • Standard since 1992 • Compression of motion video & audio at about 1.5 Mbps (VHS Quality) • Targeted at digital playback & storage • Has Random Access capabilities • Divides picture up into 8x8 pixel blocksConverts blocks to bit stream

  4. MPEG 2 • Targets higher quality compression,typically at 3-6 Mbps bit rates • Being used for Direct Broadcast TV • Large chunks of MPEG2 used in U.S. HDTV standard • Standard since 1994 MP3 • Web audio clips • Uses audio compression from MPEG 1 • 12-1 typical compression ratio

  5. MPEG 4 • Aimed at Multimedia Coding • Bit rates from 8 Kbps - 40+ Mbps • Can codes objects as opposed to NxN blocks • Ability to interact & manipulate objects • Standard in 1999 • Used in Quicktime 6, Direct TV

  6. H.261, H.263, & H.264 • Target real time videoconferencing • Subset of MPEG • Wide variety of bit rates • 64 Kbps - 128 Kbps: Face shot (video phone) • 384 Kbps: considered to be minimum speed for decent full screen videoconferencing • We are using H.263/4, mostly @ 768 Kbps • H.264 quality > H.263 > H.261 • Newer protocols require more processing power • H.261 less common today

  7. Video Delivery: Over the Air 300 m ATSC Digital FDM Since June 2009(FCC edict) 40-50 miles

  8. Video Delivery Systems • Geo-Synchronous SatelliteAnalog NTSC (Obsolete) • 1 channel per 6 MHZ of RF bandwidth • 10 foot satellite dish Newer Systems digital MPEG2 • Can get 4-6 "NTSC quality" SDTV channels per 6 MHz of RF bandwidth (TDM) • 1 ATSC HDTV signal per 6 MHz RF bandwidth • 18 inch satellite dish • MPEG4 = same quality, fewer bps

  9. 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

  10. 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

  11. 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

  12. ... ... 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

  13. Representative Video Bit Rates (Hi ↓ Lo Quality) • 1.2 Gbps Uncompressed HDTV • 19.4 Mbps ATSC ( ≈ HDTV quality) • 8 - 9 Mbps MPEG4 ( ≈ HDTV quality) • 90 Mbps Uncompressed NTSC (SDTV) • 3 - 6 Mbps MPEG2 ( ≈ SDTV quality) • 1.5 Mbps MPEG4 ( ≈ SDTV quality) • 1.5 Mbps MPEG1 ( ≈ VHS < SDTV quality) • Note: ATSC, MPEG2, & MPEG4 support a wide variety of formats (SDTV ↔ HDTV)

  14. Representative Video Bit Rates (Hi ↓ Lo Quality) • 1.2 Gbps Uncompressed HDTV • 19.4 Mbps ATSC ( ≈ HDTV quality) • 8 - 9 Mbps MPEG4 ( ≈ HDTV quality) • 90 Mbps Uncompressed NTSC (SDTV) • 3 - 6 Mbps MPEG2 ( ≈ SDTV quality) • 1.5 Mbps MPEG4 ( ≈ SDTV quality) • 1.5 Mbps MPEG1 ( ≈ VHS < SDTV quality) • How Much More Compression is Still Possible? • H.264 uses 30% less bits than MPEG4 • November 2008 IEEE Communications Magazine

  15. Compression • Requires a Signal with Redundant information • Must be some predictability • Compressing a Signal • Makes Result Less Redundant • You Can't Compress Forever

  16. PSTN 33.6 Kbps Dial-Up Modem • CO Input Line Card Low Pass Filter limits BW (3 - 3.5 KHZ) • M-Ary Signaling (256 QAM or something even more complex) • Channel Capacity says max transfer is around 35 Kbps CO CO PC Server 2 Wire ‘4 Wire’ 2 Wire Digital TDM (1's & 0's) 64 Kbps Modem Protocol Modem Protocol

  17. 56 Kbps Modem requires Digital Source Modem Bank ISP CO CO PC Server Digital StatMux 1's & 0's Digital TDM 1's & 0's (ISDN, T Carrier, SONET) DiscreteVoltage (256 possible values) PC to Server traffic will be slower, similar to previous slide.

  18. Dial Up: PC to ISP Connectivity Voice network Voice Switch Local Loop Modem PC CO Home This configuration used to cause call blocking problems at some CO switches due to longer than designed-for call holding times. ISP Modem Bank To Internet

  19. Fine print indicates • Uses Acceleration (compression) • Some material won't be compressed • Actual data transmission rates = standard dial up rates

  20. Last Mile Options to the Home • Point-to- Point Microwave • Cellular type technology • Fixed sites using directional antennas

  21. Last Mile Options to the Home • Geo-synchronous Satellite • High Speed down links (300+ Kbps) • Satellite or Phone Line ‘up link’ Server ISP Phone

  22. RIP Last Mile Options to the Home • Low Earth Orbiting Satellite • Teledesic 2004? 2005? Never! • 300+ Kbps • Cellular type technologyCells MoveEarth units ‘fixed’ • Point-to-Point Laser • Currently proprietary. Up to 2.5 Gbps speeds. • Aimed at businesses • Power Lines • Not as currently configured.

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

  24. Last Mile Options • Cable Modem Network (DOCSIS) • Simplex 6 MHz downstream channels • Simplex 200 KHz to 6+ MHz upstream channels • All traffic traverses the Headend AMP ... AMP Headend ... 2nd Generation Hybrid Fiber Coax FTT curb AMP ... Copper Coax Fiber

  25. 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 TrafficDOCSIS (Data over Cable Service Interface Specification) • Internet • VoIP

  26. Cable: PC to ISP Connectivity Voice network PC Cable TV Network Voice Switch Headend EthernetNIC Voice Data Video Cable Modem Mux Voice Data Home ISP Router Cable Modem will use shared bandwidth to get to Cable TV Headend. To Internet

  27. Cable Modems • Use FDM 6 MHz channels • Ethernet Frame format mapped to QPSK or QAM RF signal • 30 - 40 Mbps downstream • 320 Kbps to 30 Mbps upstream • Downstream • Head End controls use • TDM time slots, possibly assigned for a very short duration • Upstream • Head End assigns frequency band to end users (FDM) • Head End assigns time slots (Vendor specific algorithms) • Long term assignments (TDMA-like) • Short term assignments (StatMux-like)

  28. Last Mile Options • Digital Subscriber Line (xDSL) • Rides on top of Telco access network • Runs over twisted pair cabling • Various flavors exist CO ...

  29. ADSL: PC to ISP Connectivity PC Voice network Voice Switch EthernetNIC CO Local Loop Voice (analog) Data (ATM) Data ADSL Modem Voice DSLAM Splitter Voice Data Home ISP Router ADSL off loads data traffic from CO voice switches, & provides more CO↔Home bandwidth. To Internet

  30. 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

  31. 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

  32. Asymmetric Digital Subscriber Line • Can carry • A handful of 1.5 Mbps SDTV signals • Internet traffic (in left over BW) • Standard voice call • 0 HDTV signals • ADSL2+ potentially can carry 2 HDTV channels • Two 9 Mbps MPEG4 • 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

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

  34. Video Delivery Systems Telco Digital Subscriber Line Ultimate Goal: Fiber to the Home (FTTH) Passive Optical Network No active electronics in access network ... ... Splitter Splitter Central Office Splitter ... 3rd Generation FTT home Fiber

  35. IPTV & ISP Backbones • 150 HDTV MPEG4 TV channels • 1.45 Gbps of traffic to move • StatMux, need ≈ 2.9 Gbps trunk capacity • Two OC-48's • Not a show stopper • Especially using multicastOne video stream services many customers • Video on Demand • Could be a problem • One video stream may service one customer

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