S. Mandayam/ ECOMMS/ECE Dept./Rowan University Electrical Communications Systems ECE Spring 2010 Shreekanth Mandayam ECE Department Rowan University Lecture 1a January 19, 2010

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversityPlan 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 Tuesday!

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Communications: Where are we? 4G? (what the consumer sees……………………………)

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Communications: Where are we? ? (what the consumer sees……………………………)

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

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

S. Mandayam/ ECOMMS/ECE Dept./Rowan University 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, Sprint, ……? 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?

S. Mandayam/ ECOMMS/ECE Dept./Rowan University What is a communications system? Communications Systems: Systems designed to transmit and receive information Info Source Info Source Info Sink Info Sink Comm System

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Block Diagram Receiver Rx received message to sink Transmitter Tx s(t) transmitted signal Channel r(t) received signal m(t) message from source Info Source Info Source Info Sink Info Sink n(t) noise

S. Mandayam/ ECOMMS/ECE Dept./Rowan University 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

S. Mandayam/ ECOMMS/ECE Dept./Rowan University 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 log 2 (1 + S/N) [bits/sec] R < C: No Error!!!

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Mars Orbiter (Odyssey/Mars Global Surveyer) Mars Rover (Spirit/Opportunity) DSN Antenna (on Earth) 128 kbps 12k – 3.5k bps X-Band

S. Mandayam/ ECOMMS/ECE Dept./Rowan University Wireless Comm Evolution: 3G

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversityEvolution TECHNOLOGYFEATURES 1-G Late 1970’s, early 1980’s AMPS Advanced Mobile Phone Service -Analog voice service - No data service 2-G 1990’s CDMA Code Division Multiple Access TDMA Time Division Multiple Access GSM Global System for Mobile Communications PDC Personal digital cellular Digital voice service - 9.6K to 14.4K bit/sec. - CDMA, TDMA and PDC offer one-way data transmissions only - Enhanced calling features like caller ID - No always-on data connection 3-G 2000 and beyond W-CDMA Wide-band Code Division Multiple Access CDMA-2000 Based on the Interim Standard-95 CDMA standard TD-SCDMA Time-division synchronous CDMA - Superior voice quality - Up to 2M bit/sec. always-on data - Broadband data services like video and multimedia - Enhanced roaming

S. Mandayam/ ECOMMS/ECE Dept./Rowan University And there’s more….

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS: What are we studying? Electrical Communications Systems Measures of information and noise Capacities for information transmission Design of communications systems Measures of performance Communications circuits Communications protocols Hardware INdependent Hardware dependent

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

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS: Details

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS: Course Logistics

S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS Readiness Quiz NEXT TUESDAY, Jan 26, 9:25 AM Room 204/206 CLOSED Book and Notes Topics: Complex algebra, Phasors, Fourier Series, AC Circuits BRING YOUR CALCULATOR!

S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversitySummary