Digital communications A - L
Academic Year 2024/2025 - Teacher: Giovanni SCHEMBRAExpected Learning Outcomes
Knowledge and understanding the most important elements regarding digital communications
Capture and understanding the basic elements to analyze digital transmission techniques, and the procedures for achieving the main parameters characterizing a digital and analog communication system.
Improving capabilities to analyze both vector spaces to represent signals, and techniques for analog-to-digital conversion.
Applying knowledge and understanding of the state-of-art technologies of digital communications systems, also targeted to the practical application in non-usual contexts
Skills development for analysis of reference systems of analog and digital communications systems, also aimed at the individuation of the main system parameters (signal-to-noise ratio, bit error rate, bandwidth, energy consumption, circuit complexity). The target is to allow the student to use this knowledge also for future systems, although different from the ones studied in this course.
Making judgements of the main topics of this course
Outgrowth of a sufficient level of making judgements in discovering the main peculiarities of analog and digital communications systems and of the available tools not only for the design of simple systems like the ones studied during the course, but also of more complex systems, like satellite communications, 5G e 6G, which require further maturation of what studied during the course.
Communication skills finalized to heterogeneous interlocutors
Outgrowth of an effective and high-level communications skill for topics regarding analog and digital transmission, modulation systems and transmission devices.
Learning skills of the evolutions of the topics studied during the course, independently
Outgrowth of skills for autonomous training regarding scientific evolution and specific digital communications technologies to deepen new transmission technologies for cables, fiber and wireless, also with reference to techniques applied to ADSL, LTE, 4G, 5G and 6G.
Course Structure
The course is composed of a part of theory (35 hours), and a part of practice (15 hours).
In the case lectures will be partially or fully realized remotely by a video-communications platform, what declared above could undergo some changes, in order to achieve the objectives targeted in this syllabus.
Required Prerequisites
Convolution
Bandwidth of a base-band and passband signal
Power spectrum and autocorrelation function
Periodical signals
Probability theory, random variables and random processes
Probability density function of random variables
Time-invariant linear systems, filters and distortions
Sampling of a signal and interpolation from a
sequence
Attendance of Lessons
Detailed Course Content
The course is structured in the following Elementary Teaching Units (ETU):
|
|
HOURS |
BOOKS |
|
ETU 1: Introduction
|
6 |
T1, T4 |
|
ETU 2: Source Coding and Channel Coding
|
8 |
T1, T2, T4 |
|
ETU 3: Digital Transmission of voice signals
|
8 |
T3, T4 |
|
ETU 4: Baseband Digital Transmission
|
20 |
T1, T3, T4 |
|
ETU 5: Introduction to Passband Modulations
|
6 |
T1, T3, T4 |
|
ETU 6: Digital Modulations
|
10 |
T1, T3, T4 |
Reference material
[T1] Leon W. Couch, Fondamenti di Telecomunicazioni, Prentice Hall
[T2] Alessandro Falaschi, Trasmissione dei Segnali e Sistemi di Telecomunicazione, Web edition, Versione 2.0, 2023.
[T3] K. Sam, Shanmugam “Digital and Analog Communication Systems”, John Wiley & Sons.
[T4] Appunti del docente.
Textbook Information
[T1] Leon W. Couch, Fondamenti di Telecomunicazioni, Prentice Hall
[T2] Alessandro Falaschi, Trasmissione dei Segnali e Sistemi di Telecomunicazione, Web edition, Versione 2.0, 2023.
[T3] K. Sam, Shanmugam “Digital and Analog Communication Systems”, John Wiley & Sons.
[T4] Appunti del docente
Course Planning
| Subjects | Text References | |
|---|---|---|
| 1 | ETU 1: Introduction Review of signal theory (autocorrelation, power spectral density, probability density function of a random variable, filters, white noise and Gaussian random processes, sampling). General description of a communication system, analog and digital sources. Communication channels, distortions, and noise. AWGN noisy channels. Radio channels: free space path loss (FRIIS formula). Performance parameters of a communication system (SNR, BER, SER). Metrics for measuring the noisiness of a quadrupole: noise figure, noise temperature, antenna, and system noise temperature. | T1, T4 |
| 2 | ETU 2: Source Coding and Channel Coding Information theory - Measurement of information and entropy. Examples of discrete sources. Source coding: code properties, code length, coding efficiency, block coding, Gray, Shannon-Fano, and Huffman codes. Channel coding - Block codes. Code rate. Coding/decoding delay. Linear and systematic codes. Spectral efficiency. Repetition and parity codes. Hamming weight and distance. | T1, T2, T4 |
| 3 | ETU 3: Digital Transmission of voice signals Characteristics of the voice signal. A/D conversion: sampling, uniform and non-uniform quantization, coding. Quantization SNR. A-law and μ-law compression. ITU-T and ETSI standards for voice compression. | T3, T4 |
| 4 | ETU 4: Baseband Digital Transmission The digital transmitter. Binary and M-ary line coding. Shannon-Hartley theorem for channel capacity. Digital receiver. Structure of a digital receiver. Digital demodulator. Maximum likelihood decision maker. Symbol error rate (SER) and bit error rate (BER). BER for main binary and M-ary baseband modulations. Binary digital transmission: Main binary and multilevel line codes. Line code spectrum. Clock recovery. Binary and M-ary PAM systems. Intersymbol interference (ISI) and Nyquist criterion. Eye diagram. | T1, T3, T4 |
| 5 | ETU 5: Introduction to Passband Modulations Amplitude modulation and demodulation: AM DSB, DSB-SC, SSB, and VSB. Angular modulation: FM and PM. Comparison between modulation techniques: power, bandwidth, SNR, complexity. | T1, T3, T4 |
| 6 | ETU 6: Digital Modulations Binary modulations: ASK, PSK, FSK. Performance comparison: power, bandwidth, BER, complexity. M-ary multidimensional modulations: M-PSK, QAM, M-FSK. DMT and OFDM transmission systems. | T1, T3, T4 |
Learning Assessment
Learning Assessment Procedures
The exam consists of a mid-term test and an oral
exam.
The mid-term test, lasting 3 hours, is graded according to the following 3
bands:
- Score A: The student will take the oral exam with only 2 questions on a reduced program.
- Score B: The student has two options:
- Take the oral exam with only 2 questions on a reduced program, but the final grade cannot exceed 27/30.
- Take the oral exam with 2 questions on the full program to aim for a final grade without the limitation of the previous point.
- Score C: The student will take the oral exam with 3 questions on the full program.
Students who do not pass the mid-term test or do
not participate at all, must take a full exam, which includes a numerical
exercise.
The mid-term test is
valid until September 30th of the same year in which the course was delivered.
After this date, all students must take a full exam, which includes a numerical
exercise.