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Final Exam

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Final Exam

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  1. ECEN5553 Telecom SystemsDr. George ScheetsWeek #13Read [28] "The IEEE 802.11 Universe"[29a] "Breaking the Gigabit-per-second Barrier with 802.11ac"[29b] "Wi-Fi Making Big New Waves"[29c] "Next-Generation Wi-Fi: As Fast as We'll Need?"Read [30] What's Next for Wi-Fi? "The Wi-Fi-Enabled World" "Getting Ready for Gigabit Wi-Fi" "Wireless LANs: Assuring Optimal Performance"Term Paper (Late Fee = -1 per working day)15 November (Remote DL) Exam #2 final results (90 points max) Hi = 88.8, Low = 58.8, Ave = 77.78, σ = 8.24 A > 81, B > 68, C > 59, D > 50Final Exam 9 December, 1400-1550 hours (Local) No later than 16 December (Remote DL)

  2. Final Exam • Work 5 of 7 pages • 2 - 3 pages will be from the Fall '12 final • 85-90% Notes10-15% Readings • Use the space provided! Start Reviewing Now!

  3. To Get a Good Grade... Answer the questions in the test space provided. Give the instructor the feeling you could've said more. Hopefully you started studying well in advance of the test. Hopefully you've read the required articles. Notes, Power Point slides, & Required Readings are all testable.

  4. Syllabus Grade Break Points • A > 410 points (90%) • B > 364 points (80%) • C > 319 points (70%) • D > 273 points (60%) • > 410 points? Guaranteed an A • > 364 but < 410? Guaranteed a B, etc. • Otherwise, at mercy of Court

  5. Fall 2012 Break Points • A > 391 points (86%) • B > 337 points (74%) • C > 291 points (64%) • D > 246 points (55%) • Fall 2013 points likely not the same. • Probably in same vicinity • Won't know for sure until everything's graded

  6. Mobile Wireless Options (MAN) • Analog & FDM • AMPS, 1G Data Speeds < 14.4 Kbps Gone in 2008 • Time Division Multiple Access • U.S. TDMA, 2G, gone → GSM • GSM, 2G, Data Speeds < 14.4 KbpsObsolete • Code Division Multiple Access • TIA-95 CDMA (a.k.a. IS-95 or CDMA1), 2GData Speeds < 14.4 KbpsObsolete

  7. DSSS - Transmit Side +1 Traffic (9 Kbps) time -1 Spreading Signal 27 Kcps +1 +1 +1 time -1 -1 -1 Transmitted Signal 27 Kcps (mapped onto hi freq) +1 +1 +1 +1 time -1 -1

  8. X Wireless 27 Kcps Square Pulses RF Transmitter BPSK output 27 Kcps 90% of power in 54 KHz BW centered at fc Hertz cos(2πfct) RCVR Front End BPSK input 27 Kcps + noise Low Pass Filter 27 Kcps Square Pulses + filtered noise X cos(2πfct)

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

  10. +1 +1 -1 -1 Received Signal #2 27 Kcps +1 +1 +1 time +1 DSSS-Receiver 2nd Signal active -1 -1 Despreading Signal #1 27 Kcps +1 +1 +1 time -1 -1 -1 Recovered Garbage from 2nd signal +1 time -1

  11. -2 +2 +1 +1 -1 -1 +1 Recovered Traffic 9 Kbps time -1 Recovered Garbage from 2nd signal +1 time -1 Input to Matched Filter Detector (sum) time DSSS-Receiver 2 Signals active

  12. +2 -2 Input to Matched Filter Detector (sum) time TBit Receiver Matched Filter Detector Output +1 time -1 Additional signals transmitting at the same time increase the apparent noise seen by our system. Message (voice) BER will increase.

  13. Different channels use all of the bandwidth all of the time. CDMA frequency Channels use different codes. Other channels cause noise-like interference. time

  14. CDMA: 3D View frequency code #3 code #2 code #1 time

  15. Multiplexing Schemes Frequency Division Mutiplexing Time Division Multiplexing Statistical Multiplexing Code Division Multiplexing

  16. Mobile Wireless Evolution 2G: Voice! Voice! 2.5G: One eye on data. 3G: Voice & Data 4G: Hi Speed Data LTE (4G) Sprint 2012-2013 WiMax Development halted in 2005

  17. Mobile Wireless Options (MAN) • TDMA Evolution • U.S. TDMA, 2G, gone → GSM • GSM, 2G, Data Speeds < 14.4 Kbps, mostly gone • Enhanced Data Rate for Global Evolution (EDGE) • 2.5G GSM service, Data Rates < 90 - 180 Kbps • TDMA: Multiple time slots & higher M-Ary • Mostly gone. Replaced by... • Universal Mobile Telephone Service (UMTS) • 3G GSM, Data Rates from 384 Kbps to 2+ Mbps • Wideband CDMA, 5 MHz BW. • Widespread U.S. deployment.

  18. Mobile Wireless Options (MAN) • High Speed Packet Access (HSPA) • 3G GSM, UMTS upgrade, data < 2(4+) Mbps up(down)link • W-CDMA: more codes & higher M-Ary for data • Fairly widespread U.S. deployment • Code Division Multiple Access 2000 (CDMA 2000) • 3rd Generation • Data Rates 200 Kbps to maybe 3+ Mbps • Fairly widespread U.S. deployment

  19. Different channels use some of the frequency all of the time. FDMFDMA frequency 1 2 3 4 time

  20. 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 narrow band interference Less susceptible to multipath time

  21. 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

  22. 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

  23. Mobile Wireless Options (MAN) • Long Term Evolution (LTE) • OFDM, MIMO, Data Rates > 60 Mbps • Initially Deployed in 2011. Marketed as 4G. • LTE-Advanced • Seeing initial deployment in 2013 • 1-2 Gbps speeds claimed on downlink • Some Trade Pub articles → Don't need a LAN • Speeds ↓ as distance from BS ↑ & BW shared • WiMax (IEEE 802.16) • OFDM, MIMO, Data Rates < 10 - 70 Mbps • Used as back haul, fixed wireless. Alternative to LTE? No. • Deployed by Sprint & Clearwire. Sprint moving to LTE.

  24. Wireless LAN’s • 1-2 Mbps over 100-200 m (1997: 802.11) • 11 Mbps over 50m (1999: 802.11b) • 54 Mbps over 10-20m (2003: 802.11g) • Uses same frequency band as 802.11 & 802.11bGenerally “backwards compatible” • 54 Mbps over 10-20m (1999: 802.11a) • Not widely available until 2002 • Not compatible with other 802.11 flavors • < 600 Mbps 802.11n (2009) • Uses MIMO & OFDM • Usable bit rate probably at or below 248 Mbps • Small Cells

  25. IEEE 802.11 Comparison Source: "IEEE 802.11ac: From Channelization to Multi-User MIMO", IEEE Communications Magazine, October 2013

  26. WiFi Speed vs. Distance source: 13 May 2002 Network World

  27. 802.11 Flow Chart (Simplified) No Packet to Send? Binary Exponential Back-off Used (Similar to 802.3) Min Wait: 0 Max Wait: 51.2 msec No Media Quiet? Back-off Yes No Media Quiet? Quiet for IFS? No Yes Yes Transmit ACK received? No Yes

  28. INMARSAT Phones Recently smaller phones have become available for use with latest satellites.

  29. Parabolic Antennas

  30. Geosynchronous Satellite vs Sun, Mid-day, Northern Hemisphere Summer Sun is above satellite orbital plane. Fall Sun → same plane as satellite. Winter Sun is below satellite orbital plane. x x x x Spring Sun → same plane as Satellite.

  31. 2013 Fall Sun Outage, Microspace's AMC-1 x Source: www.ses.com/4551568/sun-outage-data

  32. WiFi Sales

  33. http://cp.literature.agilent.com/litweb/pdf/5990-6706EN.pdf

  34. 2004 Mobile Telephony Technologies 1.439 Billion users worldwide source: http://www.gsmworld.com/news/statistics/ CDMA Analog GSM 3GSM Other US TDMA

  35. 2009 Mobile Telephony Technologies 4.310 Billion Cell Users of 6.797 Billion Earthlings source: gsmworld.com/newsroom/market-data/market_data_summary.htm CDMA1 CDMA 2000 GSM 3GSM Other

  36. 2013 Mobile Telephony Technologies source: gsmworld.com no longer provides these numbers CDMA1 CDMA 2000 GSM 3GSM Other LTE

  37. Cell Towerwith Point-to-Point RF link Protocols Proprietary 802.16 802.11

  38. Free Space Lasers Sources: www.fsona.com www.engadget.com/media/2006/02/gigabeam.jpg

  39. Comparison: RF vs Optical Backhaul XX GHz Source:"The Next Challenge for Cellular Networks: Backhaul", IEEE Microwave Magazine, August 2009.

  40. Hughes Net (2013)

  41. Backhaul Networks • 1G Circuit Switched TDM (PSTN) • Carrying voice & a little data on the side • 1G & 2G cell networks • 2G Hybrid • TDM carrying voice • Packet Switched StatMux network carrying data • 2.5G to 3G cell networks • 3G Packet Switched Statistical Multiplexing • Carrying data, video, & a little voice on the side • 3G & 4G cell networks

  42. Market Split for Backhaul Gear Source: "High-Capacity Ethernet Backhaul Radio Systems for Advanced Mobile Data Networks", IEEE Microwave Magazine, August 2009.

  43. Iridium 6 Low Earth orbits, 11 satellites per polar orbit Not-so-miniature phone. image sources: Wikipedia & www.iridium.com

  44. Iridium in Antarctica Source: wikipedia

  45. 1 6 5 4 7 2 8 3 Globalstar image source: www.globalstar.com

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