EE107 Communication Systems. Introduction

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1 EE107 Communication Systems Introduction Mai Vu 5 September 2017

2 What is communication? Overview Exchanging/imparting of information What is a communication system? A system facilitating communication between two entities Mai Vu 2

3 (Very) Brief History of Communication Methods Sound Carrier Visual Semaphore (1793) Electrical s (1800 s ) Mai Vu 3

4 Some Important Milestones 1876 Invention of telephone (Alexander Graham Bell) 1896 First wireless telegraphy (Guglielmo Marconi) 1906 First AM radio broadcasting (Reginald A. Fessenden) 1935 FM radio demonstration (Edwin Armstrong) 1948 Mathematical theory of communication (Claude Shannon) Invention of the transistor (Shockley, Brattain, Bardeen) 1971 First wireless computer network (AlohaNet) 1984 Analog cellular service (Motorolla) 1991 Digital cellular service (GSM) First wireless LAN developed (AT&T) G cellular service launched G cellular services G cellular services (expected) Mai Vu 4

5 Electrical Communication System Same information? Information Source Input message Transmitter Transmitted Channel Received Receiver Output message Destination Noise and Distortion Mai Vu 5

6 Tx and Rx Signals Transmitted Received (without noise) Received (with noise) Recovered Mai Vu 6

Analog and Digital Communication Systems Analog system Input (analog) Modulation Transmitted Channel Received Demodulation Output Signals stay analog throughout Input (analog) A/D converter Digital

7 Analog and Digital Communication Systems Analog system Input (analog) Modulation Transmitted Channel Received Demodulation Output Signals stay analog throughout Input (analog) A/D converter Digital bits Digital system D/A converter Output (analog) Digital bits Coding Transmitted Received Decoding Input symbols Modulation Channel Demodulation Output symbols Information is digitized, but the channel is still analog Mai Vu 7

8 Resources and constraints Bandwidth: A precious and very expensive resource Twisted pair cable Plain old telephone wire Mai Vu 8

9 Resources and constraints: Wireless spectrum Mai Vu 9

10 Wireless spectrum example Licensing for exclusive use of the spectrum bands (auction since 1994). Examples of FCC auctions: #97 (2014): AWS-3 (Advanced Wireless Services) bands for $41.3 B ( MHz, MHz, and MHz bands) #73 (2008): 700 MHz (public safety spectrum) for $19.5 B ( MHz band) #66 (2006): AWS-1 bands for $13.7 B ( MHz and MHz) Current research for use of mmwave spectrum ( GHz) Mai Vu 10

11 Resources and constraints Power Is also very important Often measured in terms of SNR to noise ratio Often limited by availability and/or regulation (interference cap, spectrum mask) Shannon s law bandwidth -to-noise ratio R = W log 1 + SNR bits / sec data rate This rate is the maximum limit! Mai Vu 11

12 Constraints and Performance metrics Resources / Constraints: Bandwidth Power Processing technology Performance measures of a communication system: Data rate / Transmission rate Spectral efficiency (bps / Hz) SNR (often for analog systems) Error probability (for digital systems) Mai Vu 12

13 Topics in this course For the major part of this course, we study s and techniques to process these s in a communication system Modulation, demodulation Quantization and coding Pulse shaping Signal multiplexing in time and frequency In a small portion, we also analyze and evaluate performance of various communication techniques How do you tell if one system is better than another? Or just how well it performs? At a basic level, we will design a communication system or a portion according to simple specifications. Mai Vu 13

14 Syllabus Representation of s and systems Amplitude modulation (AM) Angle modulation (FM) The transition from analog to digital Baseband digital transmission Band-pass digital transmission Channel capacity and system examples Mai Vu 14

15 Course specifics TA: Alireza Alizadeh Holds problem sessions Grades all homework and labs Holds OH and available for help ( or in-person) on homework, labs, project Lectures: T/Th 3:00 4:15pm, H108 Problem sessions: time and room TBD Assessment: Quizzes: in-class quizzes Midterm exam: October 24 Project demos: December 11 Final exam: December 19 Office hours: Prof. Vu: F 1:00-2:00pm TA: TBA Mai Vu 15

ECE 457 Communication Systems. Selin Aviyente Assistant Professor Electrical & Computer Engineering

ECE 457 Communication Systems. Selin Aviyente Assistant Professor Electrical & Computer Engineering ECE 457 Communication Systems Selin Aviyente Assistant Professor Electrical & Computer Engineering Announcements Class Web Page: http://www.egr.msu.edu/~aviyente/ece 457.htm M, W, F 10:20-11:10 a.m. Office