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Electrical Communications Systems ECE.09.331 Spring 2008

Electrical Communications Systems ECE.09.331 Spring 2008. Lecture 1a January 22, 2008. Shreekanth Mandayam ECE Department Rowan University http://users.rowan.edu/~shreek/spring08/ecomms/. Plan. Why are we studying ECOMMS? Technology successes, Trends and Decisions

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Electrical Communications Systems ECE.09.331 Spring 2008

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  1. Electrical Communications SystemsECE.09.331Spring 2008 Lecture 1aJanuary 22, 2008 Shreekanth Mandayam ECE Department Rowan University http://users.rowan.edu/~shreek/spring08/ecomms/

  2. Plan • Why are we studying ECOMMS? • Technology successes, Trends and Decisions • What is a communications system? • Objectives • Block diagram • What limits our ability to communicate? • Fundamental limits - Shannon’s Theorem • Wireless communications evolution • What are we studying in this course? • Course logistics • ECOMMS Readiness QUIZ, next Monday!

  3. Communications: Where are we? 4GW? 1975 2007 http://www.apple.com/iphone/ (what the consumer sees……………………………)

  4. NASA – Imminent Communications Needs The needs that ISHM helps satisfy: Reliability & Safety Lockheed-Martin to build Orion Lunar Habitat

  5. Decisions, decisions….. • I live in the Philadelphia metro area. What cell-phone carrier should I choose? What if travel to Europe every few weeks? Or Japan? • Verizon, AT&T, T-Mobile, ……? • I’m designing the next generation microprocessor. It’s going to be connected to Internet2. How do I design the right size the memory buffer? • I’m designing the communications protocols for the manned exploration of Mars. What’s the right bandwidth/data rate for control signal transmission?

  6. Info Sink Info Source Comm System What is a communications system? • Communications Systems: Systems designed to transmit and receive information

  7. Info Source m(t) message from source n(t) noise Receiver Rx Transmitter Tx Channel received message to sink s(t) transmitted signal r(t) received signal Block Diagram Info Sink

  8. What limits our ability to communicate? • NOISE!!!!! • Noise: an unwanted, random fluctuation in the signal • Without the effects of noise, a message with infinitesimally small power could be transmitted over infinitely large distances • ALL advances in communications technology are advances to combat the effects of noise

  9. Fundamental Limit: Shannon’s Theorem (1948,1949) • Theoretical limit for error-free transmission in a communications system in the presence of noise • Source Data Rate: R [bits/sec] • Channel Capacity: C = B log2(1 + S/N) [bits/sec] • R < C: No Error!!!

  10. Mars Orbiter (Odyssey/Mars Global Surveyer) 12k – 3.5k bps DSN Antenna (on Earth) X-Band 128 kbps Mars Rover (Spirit/Opportunity)

  11. Wireless Comm Evolution: UMTS (3G) http://www.3g-generation.com/ http://www.nttdocomo.com/reports/010902_ir_presentation_january.pdf

  12. Evolution

  13. And there’s more…. Joseph M. Nowack, http://www.jacksons.net/~tac/

  14. Hardware dependent Hardware INdependent ECOMMS: What are we studying? Electrical Communications Systems • Communications protocols • Measures of information and noise • Capacities for information transmission • Design of communications systems • Measures of performance • Communications circuits

  15. Receiver Rx Transmitter Tx Channel m(t) s(t) r(t) ECOMMS: Topics Noise Wire/wireless Antennas/ Coupling Demodulation circuits and systems DSP Antennas/ Coupling Modulation circuits and systems DSP Analog/digital Protocols Fundamental limits

  16. ECOMMS: Details

  17. ECOMMS: Course Logistics http://users.rowan.edu/~shreek/spring08/ecomms/

  18. ECOMMS Readiness Quiz NEXT MONDAY, Jan 28, 12:40 PM Room 204/206 CLOSED Book and Notes Topics: Complex algebra, Phasors, Fourier Series, AC Circuits BRING YOUR CALCULATOR!

  19. Summary

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