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Communication Theory

Communication Theory. Prof. Deli Qiao Department of Communications Engineering. Instructor Information. Office: 245 Email: dlqiao@ce.ecnu.edu.cn Web: http://faculty.ecnu.edu.cn/s/2915/main.jspy Phone: 54345492 Office Hours: Mon. & Fri. 0:30pm~1:30pm. Textbook. J. Proakis. 樊昌信改编.

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Communication Theory

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  1. Communication Theory Prof. Deli Qiao Department of Communications Engineering

  2. Instructor Information • Office: 245 • Email: dlqiao@ce.ecnu.edu.cn • Web: http://faculty.ecnu.edu.cn/s/2915/main.jspy • Phone: 54345492 • Office Hours: Mon. & Fri. 0:30pm~1:30pm

  3. Textbook J. Proakis 樊昌信改编

  4. Reading Materials • 通信原理（Principles of Communications）, Lecture Notes, Prof. Meixia Tao, Shanghai Jiao Tong University.[http://iwct.sjtu.edu.cn/Personal/mxtao/teaching.html] • Introduction to analog and digital communications, Lecture Notes, Ohio State University. [http://www2.ece.ohio-state.edu/~schniter/ee501/index.html]

  5. Course Objective • The primary objective of this course is • to introduce the basic techniques used in modern communication systems, and • to provide fundamental tools and methodologies in analysis and design of these systems • After this course, the students are expected to • understand the information flow in communication systems and the theories and techniques of modulation, coding and transmission, and • analyze the merits and demerits of current communication systems and to eventually perform research and development (R&D) related to new systems

  6. Outline • Introduction • Signal, random variable, random process and spectra • Analog modulation • Analog to digital conversion • Digital transmission through baseband channels • Signal space representation • Optimal receivers • Digital modulation techniques • Channel coding • Synchronization • Information theory*

  7. Grades • Quiz (15%) • About 10-15 times, each one and only one problem. • Homework (15%) • About 4-7 times, including Matlab simulation problems. • Mid-term Exam (20%) • In-class open book. • Final Exam (50%)

  8. In-Class Rules • Shutdown smartphone and donot put on desk! • No food/drink in class and put your drinking bottle aside the desk! • No mutual conversation ! • Prepare, make notes and review frequently! • Practice makes perfect!

  9. Maxim (格言)

  10. Outline • Introduction • Signal, random variable, random process and spectra • Analog modulation • Analog to digital conversion • Digital transmission through baseband channels • Signal space representation • Optimal receivers • Digital modulation techniques • Channel coding • Synchronization • Information theory

  11. Introduction The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point. ---Claude E. Shannon 1948

  12. Introduction • Historic signal (smoke, flag, horn) • After electricity • 1838: telegraph (S. Morse) • 1876: telephone (A. Bell) • 1863: electromagnetic wave (J. Maxwell, found 1887 by Hertz) • 1895: radio (G. Marconi) • 1901: transatlantic transmissions (Marconi, 2200 miles) 1909 Nobel Prize

  13. Introduction • Early 20th century • Most communication systems including the early version of cellular systems developed in 1940s are analog. • Engineering designs are ad-hoc, tailored for each specific application.

  14. Introduction Modern Communication Systems

  15. Introduction • General questions • Is there a general methodology for designing communication systems? • Is there a limit to how fast one can communicate?

  16. Introduction

  17. Introduction

  18. Introduction • System diagram

  19. Introduction

  20. Introduction

  21. Introduction

  22. Introduction • Wireless channel free-space propagation

  23. Introduction • The additive noise channel • Linear time-invariant (LTI) filter channel

  24. Introduction • Linear time-variant filter channel • A multi-path channel

  25. Introduction • Analog communication systems • Digital communication systems

  26. Introduction

  27. Introduction

  28. Introduction • Why digital systems? • Robustness to channel noise and external interference • Security of information during its transmission from source to destination • Integration of diverse source information into a common format • Low cost DSP chips by very cheap VLSI designs

  29. Introduction • Performance metrics of communication systems • Reliability: SNR for analog; Bit error rate (BER) for digital • Efficiency: Spectral efficiency vs. Energy efficiency

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