Course detail

# Theory of Communication

FEKT-MPC-TSDAcad. year: 2021/2022

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.

Guarantor

Department

Learning outcomes of the course unit

- 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).

Prerequisites

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

Co-requisites

Recommended optional programme components

Literature

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

HAYKIN, S.; MOHER, M. Introduction to Analog & Digital Communications. 2nd ed., New Jersey (USA) : John Wiley & Sons, 2007. 515 p. ISBN 0-471-43222-9 (EN)

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)

Planned learning activities and teaching methods

Assesment methods and criteria linked to learning outcomes

- up to 10 points for all laboratory measurements, during them student always obtain points at the end of each lesson when teacher verify correctness of results measured and conclusions stated in the given protocol,

- up to 10 points for the professional trainings according to the result of computer quiz of student’s knowledge which is usually on the program after the 5th training,

- up to 10 points for all computer exercises, during them student obtain points for correctly processed tasks submitted in-time,

- up to 70 points for final exam, which has a written form.

Only students who have completed all laboratory measurements, all professional trainings and have more than 0 points from the computer quiz of their knowledge can take the final exam. If the examinator has a problem with the evaluation of the written exam, he/she can put supplement oral questions to the student. Each student can take the computer quiz only once.

Language of instruction

Work placements

Course curriculum

Lectures:

1) Signals in communication systems. Basic waveform representations of binary digits. Modulation rate, bit rate. Computation of signal examples.

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

Laboratory measurements:

1) Waveforms and frequency spectra of basic signals.

2) Methods for the reduction of error probability.

3) Data encoding for transmission.

4) Scrambler / descrambler.

5) Basic keying techniques.

6) Spare exercise.

Professional trainings:

1) Waveforms and frequency spectra of data baseband signals. Calculation of basic signal parameters.

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.

Computer excercises:

1) MATLAB, HDB3 encoder, AWGN channel model.

2) Matched filter and correlation receiver.

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

4) Principle of quadrature modulations (QPSK, 16QAM).

5) Pulse modulations (DM, ADM, SDM, PCM).

6) Spread-spectrum techniques.

Aims

Specification of controlled education, way of implementation and compensation for absences

#### Type of course unit

Laboratory exercise

Teacher / Lecturer

eLearning

**eLearning:**currently opened course