Learning objectives
The goals of the course, in terms of knowledge and comprehension, are the following:
- to give to the students an overview of main communication systems, with particular attention to digital communications.
The abilities to use the knowledge and comprehension skills outline above can be summarized as follows:
- to understand the operational principles of a communication system from its architecture
- to understand the trade-offs of a communication system.
Prerequisites
Basic knowledge of probability theory is welcome, although the concepts will be reviewed in the course.
Course unit content
Introduction to communication systems. The ISO-OSI model. Characterization of the wireless propagation medium. Communication noise. Digital communications. Foundations of information theory. Contention access methods (with fixed resource assignment and with random access). Cellular networks. Evolution of cellular systems from 1G to 5G. Wireless communications.
Full programme
LECTURE 1
Introduction, motivations.
LECTURE 2
Decibel. Properties. Logarithmic scales. Loss and gain.
LECTURE 3
Wave. Wavelength. Free space loss. Effective area of an antenna. Fading. Rayleigh Fading. Diversity. Interleaving and deinterleaving.
LECTURE 4
Margins in communications. Outage events.
Satellite communications. Orbits. Satellite bandwidths. Main problems and solution of satellite communications.
ISO-OSI model. Layers, encapsulation. Example: sending a letter.
LECTURE 5
ISO-OSI. Physical, data-link, network, transport, session, presentation and application layer.
LECTURE 6
TCP/IP protocol. TCP and UDP. Comparison between ISO/OSI and TCP/IP.
Digital communications. Analog and discrete-time signals. Digital signals. Block diagram of a communication system. Source and channel coding.
LECTURE 7
Linearly modulated digital signals. Inter-symbol interference.
supporting pulses: a comparison between sinc and rectangular pulses.
Bandwidth. Base-band and pass-band signals.
Bandpass modulations. Amplitude modulation (AM).
LECTURE 8
Frequency division multiplexing (FDM).
Frequency modulation (FM) and phase modulation (PM).
A comparison between AM, FM e PM.
In-phase and quadrature components.
LECTURE 9
In-phase and quadrature components.
Signal detection: return in baseband and digital demodulation.
Multilevel constellations.
Noise.
LECTURE 10
Solution of exercises.
LECTURE 11
Solution of exercise.
Noise. Review of probability theory (autocorrelation function, power spectral density (PSD), variance).
Two- and one-sided PSD.
Noise examples. White noise. PSD of white noise. thermal noise.
LECTURE 12
Noise power. Noise equivalent bandwidth.
Noisy devices. Noise equivalent temperature.
Noise figure.
Signal to noise ratio (SNR).
Noisy channels.
Bit error rate. Conditional probabilities.
LECTURE 13
Q function.
Bit error rate for a binary transmission.
Decision rule for multilevel constellations.
LECTURE 14
Regenerative repeaters.
Information theory. Properties of information. Entropy.
LECTURE 15
Mutual information. Channel capacity.
Shannon-Hartley law. Shannon capacity.
Average mutual information. Example: binary symmetric channel.
LECTURE 16
Coding.
Source, channel, line coding.
Code rate.
Repetition code. Detection and correction of errors in a repetition code. Error probability with coding.
Parity check code.
LECTURE 17
Code gain.
Code redundancy: relation with information rate.
Multiple access techniques. MAC and LLC layers.
Frequency division multiple access (FDMA), time-division multiple access (TDMA) and code division multiple access (CDMA).
First problems of FDMA, TDMA e CDMA.
LECTURE 18
Solution of exercises.
LECTURE 19
Solution of exercises.
Direct sequence spectrum (DSS). Transmitter and receiver.
DSS with interference tone.
CDMA. Near-far problem.
A capacity comparison of FDMA, TDMA e CDMA.
LECTURE 20
Dynamic allocation of resources.
Collision problem. Throughput.
Aloha. Performance of aloha.
Slotted-aloha.
Carrier sense multiple access (CSMA).
CSMA with collision detection (CSMA-CD).
Probability of successful transmission.
Ethernet. Ethernet devices.
Manchester code.
LECTURE 21
Bridges in virtual LANs.
Backoff strategy. Channel efficiency: mean waiting time.
Ethernet cables: twisted cables, optical fibers.
Optical fibers: advantages.
Single-mode and multi-mode fibers.
Wireless networks: problems.
Frequency hop spread spectrum (FHSS). Fast FHSS.
Hidden and exposed node problem.
LECTURE 22
Standard 802.11 of wireless networks.
Multiple-input multiple-output (MIMO).
Cellular networks. Handover.
Cells. Reuse concept. Reuse distance.
LECTURE 23
Solution of exercises.
Signal to interference noise in cellular networks.
1G standard.
LECTURE 24
2G, 3G, 4G, 5G standards.
Multipath fading: channel model.
Orthogonal frequency division multiplexing (OFDM).
Bibliography
- A. B. Carlson e P. B. Crilly, Communication Systems: an Introduction to Signals and Noise in Electrical Communication, Mcgraw Hill Higher Education, 5th edition, 2010. ISBN-13: 978-0071263320.
- A. S. Tannenbaum e D. Wetherall, Reti di calcolatori, Pearson, 5th edition, 2018, ISBN: 9788891908254
Other books of interest:
- K. Pahlavan e Prashant Krishnamurthy, Principles of Wireless Networks: a Unified Approach, Prentice Hall (Communications Engineering and Emerging Technologies Series), 2001. ISBN-13: 978-0130930033.
- P. M. Shankar, Introduction to Wireless Systems, Wiley, 2001, ISBN-13: 978-0471321675.
- S. Haykin e M. Moher, Modern Wireless Communications, Prentice Hall, 2004. ISBN-13: 978-0130224729.
- F. Muratore (Ed.), UMTS: Mobile Communications for the Future, Wiley, 2001, ISBN: 0-471-49829-7.
- Rysay Research/3G Americas, HSPA to LTE-Advanced: 3GPP Broadband Evolution to IMT-Advanced (4G), September 2009.
Teaching methods
During the lectures, various topics related to performance analysis of communication systems, as detailed in the program, will be covered. Both slides and blackboard will be used. Some exercises, given to the students in advance, will be solved during class. The slides of the course will be provided on the Elly platform.
If the class activity would not be possible due to the COVID-19 pandemic, the lectures will be given by video lectures available on the platform TEAMS.
Assessment methods and criteria
The exams will be on-site or by remote connection depending on the University regulations at the time of the exam.
The regular exam, made during official exam sessions, is written, based on exercises and open-ended questions.
If note explicitly indicated, all questions have the same importance.
Other information
The teaching and support material will be provided in part by the teacher.
