# 35114 - Communications Systems (2nd Cycle)

### Course Unit Page

• Teacher Davide Dardari

• Credits 6

• SSD ING-INF/03

• Language Italian

• Course Timetable from Feb 21, 2020 to Jun 05, 2020

### SDGs

This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.

## Learning outcomes

At the end of the course, the student will be able to apply principles of digital communication systems. In particular, the student will know how to design a wireless communication system by applying specific methods to mitigate the propagation effects, including multi-antenna techniques. Moreover, the student will be able to analyze fourth and fifth generation cellular systems (LTE/5G).

## Course contents

1. Introduction to wireless systems.
1. Introduction to the course: Evolution of communication systems.
2. Recalls: Real and complex Gaussian random variables. Rayleigh, exponential and chi-square statistics. Real and complex Gaussian vectors. Basic matrix algebra, eigenvalue and single-value decomposition (SVD).
3. The wireless channel: Frequency and time selectivity of the wireless channel. Coherence time and bandwidth. Multipath propagation: the tapped delay line model. The Clarke model: Rayleigh fading, Jakes spectrum.
4. Geometric representation of signals. Low-pass discrete-time equivalent model of band-pass signals.
2. Elements of detection and estimation theory.
1. Introduction to detection theory. Hypothesis test: the MAP criterium for the minimum probability of error. The maximum likelihood (ML) test. Examples.
2. Optimal detection of 2 waveforms in AWGN: correlator and matched filter receivers. Examples.
3. Introduction to estimation theory: Bayesian estimation (MMSE, MAP), classical estimation (MVU, ML, Cramer-Rao bound). Examples.
3. Optimal transmission in bandlimited non-selective channels.
1. Linear modulations: Constellation and spectral characteristics. The conventional signal-to-noise ratio Eb/No. Optimal transmission in AWGN: MAP and ML criteria. Particular case: symbol-by-symbol detection.General expression of the (un-coded and coded) probability of error: union bound.
2. Examples of constellations and associated (un-coded) probability of error: L-ASK, L-PSK, M-QAM. Definition of spectral efficiency and considerations on the trade-off between spectral and energy efficiency.
4. Transmission in the presence of channel selectivity.
1. Transmission in the presence of flat fading. Link budget criteria in the presence of fast and slow fading: outage probability and average probability of error.
2. Optimal transmission in the presence of frequency selectivity: the MLSE receiver. Suboptimal schemes for adaptive equalization: Linear equalizers.
3. OFDM technique and its applications. DMT implementation, performance.
5. Multi-antenna systems (MIMO).
1. Definitions. Effect of the propagation environment (LOS, rich NLOS, keyhole).
2. SIMO system: maximal ratio combining (MRC).
3. MISO system with and without channel state information at the transmitter (CSIT): optimal scheme with CSIT (SVD-MIMO), beamforming and Alamouti scheme (no CSIT).
4. Hints on V-BLAST, Zero-forcing, MMSE, and SIC receivers.Multi-user MIMO (hints).
6. Cellular Systems.
1. Evolution from 1G to 5G. Frequency reuse, multiple access techniques, mobility management.
2. Seminars on LTE (4G), 5G, and DVB-T standards.

The acquisition of dedicated books is not required.

Bibliography for further deepening:

D. Tse and P. Viswanath, "Fundamentals of Wireless Communications", Cambridge University Press, 2005.

A. Goldsmith “Wireless Communications”, Cambridge University Press, 2005

J.Proakis, “Digital Communications”, Mc Graw Hill.

J.D. Parsons, “The Mobile Radio Propagation Channel”, Second Edition, John Wiley & Sons.

Oreste Andrisano, Davide Dardari "Appunti di Sistemi di Telecomunicazione: elementi di progetto di sistemi radiomobili”, Esculapio, Bologna, 2001.

## Teaching methods

Frontal lectures.

Homework assignments during the course.

## Assessment methods

A comprehensive oral exam will assess skills acquired during the course and evaluate the achievement of the educational objectives:

• Knowledge of the principles of digital communication systems
• Knowledge of the main design techniques when operating in the presence of anomalous propagation
• Skills in analyzing and designing a wireless communication link

The final exam assessment will be based on three specific questions related to the main objectives of the course. One out of the three questions may regard solving design and analysis exercises related to communication systems.

Optionally, students have the faculty to prepare and discuss a simulation project, previously agreed with the supervisor.

## Teaching tools

Educational material: Lecture notes presented in class will be available to students in electronic format through the School Intranet.

Simulation platform: Matlab.

## Office hours

See the website of Davide Dardari