Course detail

# Theory of Communication

FEKT-MKC-TSDAcad. year: 2023/2024

The course deals with principals, methods and characteristics of communication systems. It focuses on modern digital systems and modulation methods in particular. However, student of the course can also intensify his/her knowledge of analog modulations, their parameters and implementations. The theoretical information obtained at lectures are subsequently verified by laboratory measurements with specially designed instruments and also by computer simulations with models built in the MATLAB-SIMULINK environment. During the professional trainings students learn how to compute basic parameters needed for communication system design using practical examples.

Language of instruction

Number of ECTS credits

Mode of study

Guarantor

Department

Entry knowledge

Every student who wants to participate in laboratory exercises must have a qualification according to §6, vyhl. 50/1978 Sb., which the student must obtain before his/her first laboratory exercise!

Rules for evaluation and completion of the course

- up to 6 points for solution of all given assignments,

- up to 2 points for computer exercise (student obtain points for correctly processed tasks),

- up to 2 points for laboratory measurement (student obtain points when teacher verify correctness of results measured and conclusions stated in the submitted protocol),

- up to 20 points for two computer quizzes.

- up to 70 points for compulsory exam, which has a written form. Only students who obtained the credit are admitted to the exam. If the examinator has a problem with the evaluation of the written exam, he/she can put supplement oral questions to the student. Credit is awarded only to those students who submit all assignments and complete computer and laboratory exercises by the end of the teaching part of the semester.

Laboratory measurement and computer exercise are mandatory as well as solution of all given assignments and computer quizzes. If the student duly apologize his/her absence, missed exercise or laboratory measurement could be repeated in agreement with the teacher, but no later than the last week of the teaching period.

Aims

Student, who passed the course, is able:

- to distinguish basic types of binary signals, to compute and draw their spectra and describe principles and characteristics of the most widely used line codes,

- to list individual blocks of the digital communication system and explain their functions,

- to describe additive white Gaussian noise (AWGN) channel model, to define bit error rate, to compute probability of error reception in case of both baseband and passband binary signal transmission affected by AWGN,

- to describe principles, to define parameters and to list characteristics of basic and modern modulation methods,

- to explain the cause of intersymbol interferences (ISI) and Nyquist strategy of zero ISI in sampling moments, to draw and describe impulse responses of both raised cosine and Gaussian shaping filters,

- to describe the principle of channel equalization, to explain operations of adaptive equalizer and decision feedback equalizer,

- to explain the principle and importance of synchronization in the communication system, to explain the purpose of scrambling, to design the block diagram of a simple self-synchronizing scrambler,

- to describe principles of the automatic repeat request (ARQ) and the forward error correction (FEC), to explain the principle of interleaving, to describe methods of block and convolutional interleaving,

- to explain the difference between natural and uniform methods of sampling, the cause of aperture distortion and methods of its suppression,

- to describe principles of the pulse width modulation (PWM), the pulse position modulation (PPM) and the pulse density modulation (PDM),

- to explain the difference between uniform and non-uniform methods of quantization, to compute the power of the quantization noise, to draw the graphs of compressor and expander transfer functions,

- to describe principles and to list basic characteristics of pulse coded modulations (PCM, DPCM, DM, SDM),

- to explain principles of basic methods of signal multiplexing and multiple access,

- to describe and design the orthogonal frequency division multiplex (OFDM), to define its basic parameters and to list its typical characteristics and examples of application,

- to describe basic types of intensity modulations of light used in optoelectronics,

- to categorize the digital subscriber line systems (xDSL), to explain the principle of the increasing its transmission capacity, to draw and describe the ADSL reference model, to draw the composition of the ADSL frequency band, to explain the principle of both near-end and far-end crosstalk,

- to define and compute basic quantities used in the information theory (self-information, entropy, redundancy, mutual information, channel capacity), to explain the principle of the trellis coded modulation (TCM).

Study aids

Prerequisites and corequisites

Basic literature

DOBEŠ, J.; ŽALUD, V. Moderní radiotechnika. 1. vyd., Praha : BEN, 2006. 768 s. ISBN 80-7300-132-2 (CS)

Recommended reading

PROAKIS, J. G. Digital Communications. 4th ed., New York (USA) : McGraw-Hill, 2001. 1002 p. ISBN 0-07-232111-3 (EN)

HSU, H. P. Schaum's Outline of Theory and Problems of Analog and Digital Communications. 2nd ed., New York (USA) : McGraw-Hill, 2003. 331 p. ISBN 0-07-140228-4 (EN)

Classification of course in study plans

- Programme MKC-TIT Master's, 1. year of study, winter semester, compulsory

#### Type of course unit

Lecture

Teacher / Lecturer

Syllabus

2) Line codes. Required channel bandwidth. General digital communication system. Technical means for a signal transmission.

3) Noise in communication systems. AWGN channel. Probability of error. Matched filter. Correlation receiver.

4) Modulations of harmonic carrier wave, analog modulations AM, FM and PM.

5) Basic keying techniques (ASK, FSK, BPSK). Problems of carrier signal recovery in the BPSK receiver. Differential phase shift keying.

6) Basic parameters and features of the modulation system. Modulations QPSK, O-QPSK, MSK, FFSK, GMSK and comparison of their spectra.

7) Modulations π/4-DQPSK, 8PSK, MQAM, CAP. Digital quadrature demodulator.

8) Intersymbol interference (ISI) and pulse shaping filters. Equalizers (adaptive, DFE, Viterbi). Example of radio channel equalization.

9) Synchronization (transition detector, Early-Late gate synchronizer). Scrambling. Methods of error control. Interleaving (block i., convolutional i.). Pulse modulations (PAM, PWM, PPM).

10) Digital representations of analog signals. Quantization. Pulse coded modulations (PCM, DPCM, DM, SDM) and their simulation models.

11) Multiplexing (FDM, TDM, CDM) and multiple access (FDMA, TDMA, ALOHA). Spread spectrum systems. Orthogonal frequency division multiplex (OFDM).

12) Modulations in optoelectronics. Effect of the noise in passband.

13) Introduction to the information theory. Channel capacity. Trellis coded modulation (TCM).

Fundamentals seminar

Teacher / Lecturer

Syllabus

2) Examples of calculation of AM signal parameters. Derivation of the AM frequency spectrum. Examples of product demodulation.

3) Examples of calculation of FM and PM signal parameters. Example of stereo multiplex.

4) Demonstrations and mathematical description of digital modulations. Parameters of quadrature amplitude modulation (QAM).

5) Calculation of parameters of PAM and PWM. Dynamic range of the analog-to-digital converter. Quantization noise. Slope overload distortion of DM. Comparison of PCM and DPCM.

6) Calculation of the probability of error. Examples from information theory.

Exercise in computer lab

Teacher / Lecturer

Syllabus

2) Matched filter and correlation receiver.

3) Basic keying techniques (ASK, FSK, PSK).

4) Digital quadrature modulation and demodulation (QPSK, 16QAM).

5) Pulse modulation and demodulation (DM, ADM, SDM, PCM).

6) Spread-spectrum techniques (DSSS, FHSS).

Laboratory exercise

Teacher / Lecturer

Syllabus

2) Methods for the reduction of error probability.

3) Data encoding for transmission.

4) Scrambler / descrambler.

5) Basic keying techniques.

6) Spare exercise.