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Final Exam

Final Exam. Work 5 of 7 pages 2-3 pages will be from the Fall ‘99 final 85-90% Notes 10-15% Readings Scheduled Date Wednesday, 3 May, 1730-1920. Start Reviewing Now!. Homework.

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Final Exam

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  1. Final Exam • Work 5 of 7 pages • 2-3 pages will be from the Fall ‘99 final • 85-90% Notes10-15% Readings • Scheduled Date Wednesday, 3 May, 1730-1920 Start Reviewing Now!

  2. Homework • Readings:[19] “Speech Transmission Performance Planning in Hybrid IP/SCN Networks”[20] “Wireless Andrew: Bringing Mobile Computing to a University Community of 10 000”[21] “MPEG-4: Multimedia for our time”

  3. ISDN • The all-digital phone network • Covers OSI Layers 1-2, 3-7 • Two types of access:64Kbps B Channels (traffic)D Channels (signaling) • Two standardized InterfacesBRI (2B + 16 Kbps D) - Home or Small BusinessPRI (23B + 64 Kbps D) - Larger Business

  4. POTS Connectivity via BRI ISDN Copper Local Loop Copper Local Loop Fiber Optic Trunk CO CO Phone Phone 4 Wire 2 Wire ‘4 Wire’ 2 Wire 4 Wire Digital 64 Kbps

  5. Status of ISDN • Too Little, Too Late for large businesses • SOHO & home sales had been reviving, but trouble has arrived... • Cable Modems • Digital Subscriber Lines • B-ISDN (> 1.5 Mbps speeds) • High Speed One-Stop Digital Network • Run over ATM • Voice calls will eventually be all-digital, but maybe not as envisioned with ISDN

  6. Cellular Telephony Advantages: • Frequency Reuse • Reduced Transmitter Power Out • Reduced Multipath Problems • Reduced brain damage? • Subdividing Cells increases System Capacity • More Reliable due to cell overlap

  7. Cellular Telephony Disadvantages: • More complex • More installation hassles • BS to MTSO link & switching requirements can get out of hand

  8. Cellular Telephony - Operation • Power Up & Intermittantly ThereafterMobile communicates with BS/MTSOLocal MTSO notes in database mobile is activeIf mobile is roaming, Home MTSO is notified via SS7

  9. Cellular Telephony - Operation • Mobile to Wired callMobile transmits # to BS/MTSOUnused voice RF channel (2 frequencies) is assigned Mobile tunes to assigned channels BS & MTSO coordinate TDM time slotMTSO places call via CO to wired unit

  10. Cellular Telephony - Operation • Wired to Mobile callCall is placed to home MTSOHome MTSO pages mobile or forwards call to appropriate local MTSO, which pages mobileUnused voice RF channel (2 frequencies) is assignedBS & MTSO coordinate TDM time slotMobile tunes to assigned channel, rings

  11. Cellular Telephony - Operation • HandoffMTSO/BS/Mobile decides signal getting too weakAdjacent cells are polledUnused voice RF channel in the new cell is assignedMobile tunes to assigned channelMTSO reroutes traffic: Old BS <-> MTSO to New BS <-> MTSOTakes about 100 msec with AMPS

  12. Cellular Flavors • AMPS (analog) • uses FDMA and 30 KHz FM channels • Can move data ( < 14.4 Kbps) • IS-54/IS-136 TDMA (digital) • 3x to 6x AMPS capacity using FDMA & TDMA • Can move data ( < 14.4 Kbps) • IS-95 CDMA (digital) • a.k.a. Spread Spectrum • probable 8-10x AMPS capacity • Can move data ( < 14.4 Kbps )

  13. Different channels use some of the frequency all of the time. Example: AMPS FDMFDMA frequency Cell 1 Cell 1 Cell 2 Cell 2 1 2 3 4 time

  14. Combo of TDM & FDMExample: IS-136, GSM TDMA/FDMA frequency Cell 1 Cell 1 Cell 2 Cell 2 10 1 4 7 11 2 5 8 12 3 6 9 time 10 1 4 7 etc.

  15. DSSS - Transmit Side +1 Traffic (9 Kbps) time -1 Spreading Signal 27 Kbps +1 +1 +1 time -1 -1 -1 +1 +1 +1 +1 time Transmitted Signal 27 Kbps -1 -1

  16. +1 +1 +1 +1 time Received Signal 27 Kbps -1 -1 Despreading Signal 27 Kbps +1 +1 +1 time -1 -1 -1 Recovered Traffic 9 Kbps +1 time DSSS-Receiver -1

  17. +1 +1 +1 +1 time Received Signal 27 Kbps -1 -1 Despreading Signal #2 27 Kbps +1 time +1 -1 -1 -1 -1 Recovered Garbage at 2nd receiver + +1 +1 time -1 -1 -1 -1

  18. Different channels use all of the bandwidth all of the time. Example: IS-95 CDMA frequency Channels use different codes. Other channels cause noise-like interference. time

  19. Cellular Flavors • Personal Communications Services (PCS) • Bandwidth auctioned off by FCC in mid ’90’s • Initial offerings similar to cellular, but on higher carrier frequencies (low GHz) • Ultimate Goal: Unify wireless architectures (cell phone, pager, cordless phone, etc.) and provide anytime, anywhere digital services • Personal Communicators • Personal Phone Number • Standards used: IS-136, IS-95, GSM

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