Digital Communications


Department of Signal Theory and Communications,
Universidad Carlos III de Madrid

Area: Signal Theory and Communications

Bachelor's Degree in Telecommunications Engineering

October, 2013Share:    

60 hours course



The student has to have previously acquired some basic  knowledge on statistics, linear systems and communication theory.


This is a graduate level course that introduces the basic principles of digital communication systems, where the information is transmitted through a digital bit stream that can support many different kinds of information contents (data, digitized audio, video, etc.).

In particular, this subject studies the main methods and techniques applied in digital communication systems:

- Digital modulation formats used to convey digital information

- Digital receivers used in band-limited channels with linear distortion

- Error protection techniques used to detect and correct errors introduced by the channel

The subject is organized in 6 chapters:

1. Introduction

2. Pulse amplitude (linear) modulations.

3. Angle modulations

4. Design of digital communication systems in the presence of intersymbol interference (ISI)

5. Multipulse modulations

6. Channel coding for error protection

Some of the basic contents included in each chapter are the following ones:

1. Description of the goals of the subject.

2. PAM modulations, base-band and band pass; required bandwidth and analysis of noise in  these modulations.

3.  Phase and frequency modulations: non-linear phase modulations; frequency modulations and continuous phase modulations.

4. Receivers for digital communications: the problem of inter-symbol interference, optimal receivers and structures for channel equalizers.

5.  Multi-pulse modulations: multi-carrier modulations; spread spectrum modulations; required bandwidth and analysis of noise in these modulations.

6.  Techniques for protection against errors: basic definitions, block codes, convolutional codes and trellis coded modulation (TCM codes).


Knowledge and management of the different techniques of digital communications (linear and non-linear, multi-carrier and spread spectrum), the structure of receivers and the basic techniques for protection against errors in digital communications.

Therefore, the subject has the goal of allowing the student to acquire the following general competences:

- Knowledge and development of technical skills required in the telecommunications field with emphasis in the analysis and mathematical characterization of a digital communication system.

To achieve this goal, the student must acquire the following specific competences:

- Acquisition of the knowledge of mathematics and statistics that will be used as a tool to solve engineering problems in the context of digital communication systems.

- The ability to design and conduct experiments, as well as to analyze and interpret data and results.

- Design of a communication system with realistic constraints given by critical parameters such as cost, consumption of power, bandwidth, transmission rate, and complexity.


The main contents related with each of the chapters will be provided in a set of slides. Moreover, a bulletin with exercises will be provided for each chapter.

A practical laboratory exercise, to be performed using Matlab or Octave, is also proposed.

Finally, some example of questionnaires to perform the evaluation of the acquired knowledge is also included.


Students are expected to study the theoretical contents of the subject and then to perform the proposed exercises to put in practice the acquired theoretical knowledge.

Some questionnaires that can be used for evaluation are also included.

Last modified: Wednesday, 23 March 2022, 11:35 AM