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 communication system.
Prerequisites
Basic knowledge of probability theory is welcome, although the cocnept will be reviewed in the course.
Course unit content
Introduction to communication systems. The ISO-OSI model. Characterization of the wireless propagation medium. Contention access methods (with fixed resource assignment and with random access). Communication noise. Digital communications. Cellular networks. Evolution of cellular systems from 2G to 5G. Wireless communications.
Full programme
LECTURE 1: Introduction. Overview of the course and of telecommunications. History of communications. Ad hoc networks.
LECTURE 2: Decibel. dB scale in amplitude and power. Connection losses. Amplified systems.
LECTURE 3: Radio communications. Free-space loss. Fading. Review of basic concepts in probability theory. Solutions to fading. Outage probability. System margins. Satellite communications. Satellite orbits. Frequency bands. Main problems of satellite communications and some solutions.
LECTURE 4: ISO-OSI model. Layers. Layers overview with examples. Protocol data unit. Service data unit.
Physical layer. Simplex, half- and full-duplex transmission. Data-link layer. Byte-stuffing for frame building. Network layer. Circuit and packet switching.
LECTURE 5: Other ISO-OSI layers. Transport layer. Session layer. Presentation layer. Application layer. TCP/IP protocol.
LECTURE 6: Digital communications. Review of probability theory: probability density function, Gaussian distribution, Fourier transform.
Digital signal. Analog vs. digital signals. Block diagram of a communication system. Source and channel coding. Main problems of digital communications. Bit and symbol mapping.
LECTURE 7: Digital communications. Linearly modulated digital signals. Supporting pulses. Bandwidth. A comparison between rectangular and sinc pulses. Bandpass modulation. Amplitude modulation.
LECTURE 8: Band guard. Phase and frequency modulation. Amplitude shift keying, phase-shift keying, frequency-shift keying. Bit rate and symbol rate. In-phase and quadrature components. Constellations.
LECTURE 9: analog demodulation. In-phase and quadrature demodulation. Digital receiver. decision threshold. Noisy channel.
LECTURE 10: Noise. review of probability theory: autocorrelation function and power spectral density (PSD). thermal noise. PSD of thermal noise. Mono-lateral and bilateral PSD. White noise. Noise equivalent bandwidth. Noisy devices: equivalent noise temperature. Signal-to-noise ratio. Noise figure. Measurement of the noise figure.
LECTURE 11: Hard-decision in presence of noise. Error probability of binary transmissions. Q-function. Optimal decision threshold. Signal-to-noise ratio and error probability Regenerative systems.
LECTURE 12: Decisions with multi-level constellations Impact of the alphabet on the communication. Shannon-Hartley law. Channel capacity. Example of the additive white Gaussian noise (AWGN) channel. Impact of correlations.
LECTURE 13: Coding. Motivations. review of probability theory: binomial distribution. Repetition codes. Decoding rules. Error-correcting and error-detecting codes. Parity-check codes. Hard and soft-decision (hints).
LECTURE 14: Solution of exercises.
LECTURE 15: Solution of exercises.
LECTURE 16: MAC (medium access control) level. General strategies to access the channel. frequency division multiple access (FDMA), time-division multiple access (TDMA), code-division multiple access (CDMA). Spread spectrum. Direct sequence spectrum (DSS). Detection of DSS signals.
LECTURE 17: DSS detection. Performance of DSS in the presence of an interfering signal. CDMA. Near-far problem. Pseudo-random sequences.
LECTURE 18: Capacity comparison: FDMA, TDMA e CDMA. Random access. Collision problem. Aloha communications. Performance.
LECTURE 19: Slotted aloha. Carrier sense multiple access (CSMA). CSMA-CD: collision detection. Channel contentious. Ethernet. Ethernet devices: hub, bridge, switch, router, gateway. Manchester bit-encoding. Backoff strategy for collisions.
LECTURE 20: Evolution of Ethernet. Ethernet cables. Fiber-optic cables. Wireless networks. IEEE standard 802.11. Frequency-hop spread-spectrum. Hidden-node problem. CSMA-CA (collision avoidance).
LECTURE 21: Bridge: examples of use. Bried overview of 802.11 standard evolution. Zero-forcing equalization. Multiple-input multiple-output (MIMO).
LECTURE 22: Solutions to exercises.
LECTURE 23: Celular systems. Concept of the cell. Cell dimensioning. Frequency and factor of reuse. Handoff. Signal to interferer ratio in the downlink. Cell sectoring.
LECTURE 24: Cellular standards: 1G, 2G, 2.5G, 2.7G, 3G, 4G, 5G. Wireless 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.
