Lecture

Wireless Channel: Multipath Effects & Modulation

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In course

COM-405: Mobile networks

This course provides a detailed description of the organization and operating principles of mobile and wireless communication networks, as well as the use of wireless signals for sensing and imaging. ...

Description

This lecture covers the wireless channel, focusing on the multipath effects caused by reflections and delays, the importance of understanding modulation techniques like BPSK and QAM, and the impact of noise and attenuation on signal transmission. The instructor explains how the channel adds noise, delays the signal, attenuates its power, and rotates its phase, emphasizing the need for channel estimation and correction. The lecture also delves into the concepts of delay spread, coherence bandwidth, Doppler spread, and coherence time, highlighting their significance in designing efficient communication protocols for high-speed mobile networks.

Instructors (2)

Jean-Pierre Hubaux

Jean-Pierre Hubaux is a full professor at EPFL and head of the Laboratory for Data Security. Through his research, he contributes to laying the foundations and developing the tools for protecting privacy in today’s hyper-connected world. He has pioneered the areas of privacy and security in mobile/wireless networks and in personalized health. He is the academic director of the Center for Digital Trust (C4DT). He leads the Data Protection in Personalized Health (DPPH) project funded by the ETH Council and is a co-chair of the Data Security Work Stream of the Global Alliance for Genomics and Health (GA4GH). From 2008 to 2019 he was one of the seven commissioners of the Swiss FCC. He is a Fellow of both IEEE (2008) and ACM (2010). Recent awards: two of his papers obtained distinctions at the IEEE Symposium on Security and Privacy in 2015 and 2018. He is among the most cited researchers in privacy protection and in information security. Spoken languages: French, English, German, Italian

Haitham Al Hassanieh

Teaching & PhD PhD Students Eduard Vlad, Raphael Cannatà, Arman Maghsoudnia, Jiachen Lu, Samah Hussein Youssef, Hailan Zhang Shanbhag, Aoyu Gong Courses Intelligent systems: communications & AI COM-304 The course teaches the development of systems that solve real-world challenges in communications, signal processing, foundation models, and AI. Students will work in teams, construct their ideas, and either program available hardware prototypes or build their hardware or software system.

Official source

Ontological neighbourhood

Electrical engineering

Telecommunications: Modulation

Related concepts (32)

Amplitude modulation

Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation.

Wireless

Wireless communication (or just wireless, when the context allows) is the transfer of information (telecommunication) between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications.

Wireless LAN

A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet. Wireless LANs based on the IEEE 802.11 standards are the most widely used computer networks in the world.

Digital signal

A digital signal is a signal that represents data as a sequence of discrete values; at any given time it can only take on, at most, one of a finite number of values. This contrasts with an analog signal, which represents continuous values; at any given time it represents a real number within a continuous range of values. Simple digital signals represent information in discrete bands of analog levels. All levels within a band of values represent the same information state.

Signal transmission

In telecommunications, transmission is the process of sending or propagating an analog or digital signal via a medium that is wired, wireless, or fiber-optic. Transmission system technologies typically refer to physical layer protocol duties such as modulation, demodulation, line coding, equalization, error control, bit synchronization and multiplexing, but it may also involve higher-layer protocol duties, for example, digitizing an analog signal, and data compression.

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