Mobile Communications and Networks

The lectures “Mobile Communications” and “Wireless Networks” give an introduction to mobile communication systems. Students gain a fundamental understanding of the principles behind wireless communications and networking. Current technologies — such as 4G/5G and IEEE 802.11 — are discussed as examples. Lectures are complemented by group projects. Tutorial courses are offered by teaching assistants. The content is structured in a bottom-up manner, starting from physical layer, then covering higher layers and networking concepts.

Outline and Schedule

The lectures are structured as follows:

  1. Introduction and overview
  2. Antennas
  3. Radio propagation
  4. Diversity
  5. Channel coding and modulation
  6. Multiple access and cellular concept
  7. Medium access control (MAC) protocols
  8. Wireless LAN 802.11
  9. Network architecture and mobility protocols
  10. 4G and 5G networks
  11. Security in mobile networks
  12. Ad hoc networks
  13. Impact: Economic, health, and societal aspects

Mobile Communications (Chapters 1-8) is taught in the winter semester (Oct-Jan). Wireless Networks (Chapters 9-12) is taught in the summer semester (Mar-Jun). Each course has 4 ECTS.

The course dates, time, and location can be found at the university site. You can also subscribe to the iCalendar feed using your calendar software (e.g., Apple calendar, Outlook, Google calendar).

Requirements and Related Courses

Both lectures and accompanying exercise courses are intended for senior bachelor students and master students in information and communications engineering or informatics, and first year PhD students in engineering who have a master from a different area. Participants should have passed the bachelor lectures Computer Networks and Network Programming, Communications Engineering, and Stochastics.

Students focusing on networks and communications are encouraged to take the following lectures in the following order: Mobile Communications and Pervasive Computing in the winter semester; Sensor Networks, Wireless Networks, Information Theory, and Simulation of Networked Systems in the summer semester; Signal Processing for Communications and a seminar or project in the winter semester; and Advanced Wireless Communications and Stochastic Modeling and Analysis of Networked Systems in the summer semester.

Handouts and recordings

The handouts for the lectures are available via the links on the course outline shown below. For didactic reasons, the text on the handouts is on purposely incomplete and will be completed in the lecture. Students should bring printouts of the handouts to the lecture. Scribe and audio recordings are available for most units. The material contains copyrighted material and is not suited for redistribution.

Exercises

An accompanying exercise course is offered for better understanding, in order to train and deepen the content presented in the lecture. This course includes a set of problems to be solved.

Literature

The following textbooks are very useful:

Further literature is recommended in some chapters, e.g.:

Feedback from Students

“Thank you for this amazing course, I really enjoyed it!,” a student wrote me in the winter 2019/20. “It was amazing, I have never enjoyed a course like this one.” (2017). “Quality of teaching was at the highest level” (2016). “Very nice slides, well structured, well explained and very interesting topics” (2021). “I liked [the] professor’s enthusiasm and approach to topics.” (2021). “.. the way of how he explains is amazing!” (2024)

Contents and Material

Bettstetter giving a lecture

Christian Bettstetter giving a lecture

1. Introduction and Overview  pdf

Lectures: 1 unit (2 hours)

  • Applications
  • History and evolution of wireless communications
  • Overview of current wireless technologies
  • Key challenges in mobile and wireless systems
  • Lecture overview, teaching philosophy, and literature

2. Antennas  pdf

Lectures: 2 units

  • Antenna examples and types
  • Radio waves: Production of radio waves. Properties of radio waves. Energy transport, power density, and radiation intensity
  • Antenna characteristics: Directivity and gain. Antenna patterns. Polarization
  • Reception power (Friis equation)

Material

3. Radio Propagation  pdf

Lectures: 4 units

  • Path loss and shadowing:
    • Propagation in free space
    • Path loss models
    • Shadow fading
  • Multipath propagation:
    • Small-scale fading models: Rayleigh, Rice, Nakagami fading and outage probabilities
    • Time spread; frequency spread; time-variant behavior (fade rate, fade duration, Markov chain model); frequency-variant behavior; relationships
  • Overview of fading mitigation techniques

Material

4. Diversity  pdf

Lectures: 1 unit

  • Ideas behind diversity und design space. Time diversity, frequency diversity, spatial diversity.
  • Diversity combining schemes: Selection combining, maximum ratio combining; comparison; and outage probabilities.
  • Diversity in practice
  • Other diversity and multiple antenna techniques

Material

5. Channel Coding and Modulation

Lectures: 4 units

a. Representation of signals   pdf

  • Fourier series and transform
  • Bandwidth
  • Sampling and quantization

b. Channel coding  pdf

  • Purpose of coding in wireless communications
  • Block coding: Error detection and correction; Hamming code; CRC codes
  • Convolutional coding: Encoding, Viterbi decoding,
  • Coding gain
  • Channel coding in practice

Material

c. Modulation  pdf

  • Purpose and types of modulation
  • Linear digital modulation
  • Coherent demodulation
  • Modulation in practice
  • Spead spectrum modulation

d. Duplexing

6. Multiple Access and Cellular Concept  pdf

Lectures: 1.5 units

  • Purpose of multiple access
  • Multiple access techniques: TDMA, FDMA, CDMA, and SDMA
  • Cellular concept and channel reuse; SIR
  • Orthogonal frequency division multiplexing (OFDM)

Material

7. Medium Access Control (MAC) Protocols  pdf

Lectures: 1.5 units

  • Purpose and classification of MAC protocols
  • ALOHA and Slotted ALOHA
  • Throughput analysis
  • Carrier sense multiple access (CSMA)
  • CSMA with collision avoidance (CSMA/CA)
  • Quality of service support
  • MAC protocols in practice

Material

8. Wireless LAN  pdf

Lectures: 1 unit

  • System and protocol architecture of WLANs
  • Standardization of WLAN
  • Evolution of the physical layer in IEEE 802.11
  • Modulation and channel coding
  • Operation in the unlicensed ISM band
  • New developments and trends

. . .

Introduction to the “Wireless Networks” lecture  pdf

9. Network Architecture and Mobility Protocols  pdf pdf

Lectures: 3.5 units

  • Architecture of cellular networks
    • General architecture
    • System components in GSM, UMTS, and LTE.
  • Mobility in cellular networks
    • Addressing
    • Routing to mobile users
    • Handovers
  • Mobility in the Internet
    • Addressing and mobility problem
    • Autoconfiguration
    • Device mobility with Mobile IP
    • Service mobility

Material

10. 4G and 5G Networks

Lectures: 2 units

  • 4G: LTE physical and data-link layer. LTE protocol architecture. LTE system architecture. LTE advanced.  Download PDF
  • 5G and beyond: Guest lecture by Frank Fitzek. Download PDF

11. Security in Mobile Networks Download PDF Lecture recording available

Lectures: 2 units

  • Basic threats and countermeasures
  • Confidentiality
  • Spoofing in networks
  • Authentication in cellular networks
  • Virtual private networks (group project)
  • Wi-Fi security

12. Ad Hoc Networks Download PDF Lecture recording available

Lectures: 3 units

  • Routing and relaying
  • Connectivity and capacity
  • Technologies and platforms: Mesh IEEE 802.11s, Bluetooth, Apple AirTags (projects)

13. Impact: Economic, Health, and Societal Aspects  pdf

Lectures: 2 units

  • What impact does mobility technology have on humanity?
  • Economy: Subscriber numbers; industrial players; market characterization
  • Health: Studies on potential carcinogenicity risks and other health concerns. 5G.
  • Society: Cultural differences; digital divide and novel opportunities; pervasive comptuting