Ing Ind - Inf (Mag.)(ord. 270) - MI (474) TELECOMMUNICATION ENGINEERING - INGEGNERIA DELLE TELECOMUNICAZIONI

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054312 - DIGITAL COMMUNICATION

054313 - DIGITAL COMMUNICATION I

Ing Ind - Inf (Mag.)(ord. 270) - MI (476) ELECTRONICS ENGINEERING - INGEGNERIA ELETTRONICA

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054312 - DIGITAL COMMUNICATION

Obiettivi dell'insegnamento

The goal of the course is to make students familiar with concepts of communication and information theory and with their application to the analysis and design of complex telecommunication systems. Moreover, the course provides students with the tools that are needed to understand and apply advanced technologies that are presently used in telecommunication systems. Also, understanding, analyzing and designing optical and radio communication systems is one of the objectives of the course.

The course is finalized to teach students the basics of digital communication as bit rate and symbol rate, bandwidth, filtering of data signals, basics concepts of information theory, modulation and coding. Design of the transmit filter and of the receive filter in practical cases of interest, calculation of the limits of communication in terms of channel capacity, selection of the proper modulation scheme according to the constraints imposed by the system, performance evaluation of modulation and coding schemes are among the goals of the course.

Risultati di apprendimento attesi

Dublin Descriptors

Expected learning outcomes

1 - Knowledge and understanding

Understand the general principles of data transmission in digital communication systems, analyze and understand the requirements associated to a communication system in terms of signal bandwidth, filtering, modulation, coding.

2 - Applying knowledge and understanding

Identify and define at the block-diagram level a proper filtering, modulation and coding scheme for the most common channel models, compute the performance of transmission systems in terms of error probability for the most common channel models.

3 - Making judgements

Judge if a given filtering, modulation and coding scheme is appropriate for a practical radio or optical communication system. Recognize the design space and the degrees of freedom that can be exploited to reach given objectives in terms of performance of filtering, modulation and coding, with specific application to practical radio and optical communication systems.

4 - Communication

Communicate to other engineers with presentations and documents about filtering, modulation and coding schemes using the appropriate mathematical tools as Fourier analysis, probability theory, calculus and matrix algebra. Communicate to non-specialists the requirements, the constraints and the features of communication systems using graphical representation (block diagrams) and writings.

Argomenti trattati

Representation of Signals. Geometric representation of signals, Schwarz inequality, projection onto the signal space, Gram-Schmidt orthogonalization, geometric representation of noise, signal-to-noise ratio, matched filter. Maximum a Posteriori (MAP) detection and Maximum Likelihood detection in memoryless systems, minimum squared distance detection, correlation detection. Baseband equivalent of passband signals.

Limits of Communication. Entropy, equivocation, mutual information. Capacity of the discrete-time channel, capacity of the AWGN channel, capacity of the channel with coloured Gaussian noise, water filling.

Modulation. Nyquist filter. QAM and PSK modulation. Error probability, union bound. Law of 6 dB/bit for PSK, law of 3 dB/bit for QAM, back to the AWGN capacity formula. Modulation based on orthogonal signals, examples, performance evaluation. OFDM, cyclic prefix, frequency domain equalization for OFDM.

Binary Channel Codes. Channel capacity with a power constraint, examples of binary block codes, performance of soft and hard decoding. Generator matrix and parity check matrix, generator polynomial and parity check polynomial. Trellis representation of the code and trellis decoding. Convolutional codes, trellis decoding of convolutional codes, performance of convolutional codes. Concatenated coding.

Codes in the signal space. Multidimensional constellations, lattices, lattice partitions.

Exercise activity. Exercises on performance evaluation of communication systems.

Prerequisiti

Knowledge of Signal Theory: Fourier analysis, filtering, basics of digital signal processing.

Modalità di valutazione

There are two types of exam. Students are strongly encouraged at least to try with Type 1.

Type 1: continuous learning. Three written checks of your competence during the classes, about 30 minutes each. First check: chapters 1-3 of the handouts, at the third week. Second check: chapter 4-6 of the handouts, at the fifth week. Third check: chapters 7-8 of the handouts, at the seventh week. Each check can include an exercise and an open question. If you are not sufficient on at least 2 over 3 checks, then you fail with Type 1 and are forced to take Type 2. If you are sufficient on 2 over 3, you gain a bonus of 2 points. If you are sufficient on 3 over 3, you gain a bonus of 5 points. You will have a feedback about the results on the next week after the check. The oral is at the midterm call only. It starts with the discussion of your checks. If after the discussion you are sufficient, I propose a grade and you have two options: take the proposed grade or ask for a question with the aim of improving the proposed grade (of course, improving is not guaranteed).

If in your study plan you have DC1 (5 credits) you can take the laude if 3 over 3 checks are sufficient and if you ask for the oral question, taking a total of at least 33 points.

If in your study plan you have the full DC (10 credits) and the sum of your points on DC1 exceeds 30 points, the exceeding points will be counted for the full DC (see after for the rules).

If in your study plan you have DC1 and DC2 separately, the exceeding points possibly gained on DC1 will not be counted for DC2, but you can take the laude on DC1 as explained before.

Type 2: standard exam. No midterm call, only standard calls starting from January. Written exam (90 minutes) based on exercises and on a question on the theory. You will have a feedback about your written exam only at the oral. Oral exam based on the discussion of the written and on questions on the theory. Maximum 30 points, no possibility of laude.