Information
$\text{Here some notes on LNTwww}$
- For detailed information about our e–Learning tutorial, please see the page »About LNTwww« – a kind of „user guide”.
- On every LNTwww page, there is a link to this file at the bottom $($between »Privacy« and »Disclaimer«$)$.
- If you have difficulties with our terms, the »Glossary» may help.
- We consider this March 2023 version to be final; no further revision or expansion is currently planned.
- Therefore, there will also be no English translations of the German-language learning videos and SWF applets in the future.
- But, of course, we will continue to improve identified errors regarding content, presentation or handling in a timely manner.
- Should you notice any such inadequacies, then please send a detailed message by mail to »LNTwww@ice.cit.tum.de«.
- Below you will find a compact summary of our e-learning project with useful tips on »how to use LNTwww« sensibly.
LNTwww: An e-learning project for Communications Engineering
The e-learning project »LNTwww« offered by the »TUM Institute for Communications Engineering«[1] provides nine online courses on the subjects of »Communications Engineering« $\rm (CE)$ and »Information and Communication Technology« $\text{(I&C)}$. The target group of our e-learning online platform are students of these or similar disciplines as well as practicing engineers and scientists.
The German version »www.LNTwww.de« was created from 2001 to 2021. At the beginning of corona $($2020$)$ we started the English version, which has been finalized in 2024. In the following we refer to this version »en.lntwww.de«[1] , whose homepage can be seen in the graphic below.
Here are some features of our e-learning platform:
- »LNTwww« is freely accessible $($no need for registration$)$. No specific system requirements.
- »LNTwww« uses the free server-based software »MediaWiki«[1], just like »Wikipedia«, the best-known free encyclopedia.
- The »Book Collection«[1] link takes you to the nine courses $($which are referred to as »books«$)$ and to the collection »Biographies and Bibliographies«.
- The »Exercises«[1] link takes you to a list with a total of around $640$ exercises and $3100$ subtasks $($each with detailed sample solution$)$.
- About thirty learning videos $($in German language$)$ can get accessed via the »Videos«[1] link. These are grouped according to the individual courses.
- Via the »Applets«[1] link you have access to around thirty applets based on HTML5/JavaScript and some older shockwave flash $($SWF$)$ applets.
Other important project features are summarized in the file »About LNTwww« $($red marked link$)$, among others:
- »The didactic concept of LNTwww«[1]: These rules from 2001 still apply, although »LNTwww« has had to be continuously adapted to developments on the Internet.
- »Content and scope of LNTwww«[1]: Our online course corresponds to conventional courses with a total of $36$ semester hours per week of lectures and exercises.
LNTwww Design and Structure
»LNTwww« has a book structure. Each »course« corresponds to an own »book« that can be selected via »Book Collection«.
- Each book is divided into several »main chapters«,
- each main chapter is divided into several »chapters«, and
- each chapter comprises several »sections«.
$\text{Example A:}$ To illustrate these statements, here is an example of how to use »LNTwww«:
- After pressing the »Book Collection«[1] button, a selection screen will appear with the nine course-books as well as the book »Biographies and Bibliographies«.
- By selecting the book »Information Theory«[1], its "start page" will appear with links to the four main chapters and to the corresponding sub-chapters. Furthermore, beside a brief book summary and bibliographical references, links to exercises and to multimedia elements are part of this information page.
- We now select the first main chapter »Entropy of Discrete Sources« and of this in turn the first sub-chapter »Discrete Memoryless Sources«[1]. This exemplary sub-chapter explains in eight sections the procedure for calculating the entropy of binary and non-binary sources.
- As in conventional mathematical and technical literature, the facts are illustrated by texts, models, graphs, diagrams, equations and derivations. The last two sections of each sub-chapter contain exercises and references to the topic covered.
LNTwww Exercises
The core elements of our didactic concept are »exercises«. We believe that the sensible use of »LNTwww« by a user with previous knowledge should be to work first on the exercises related to his actual learning area and only jump to the corresponding theory section when required.
All exercises have a similar structure:
- Each exercise consists of the »exercise description« and several »subtasks«. An exercise will only get valued as solved if all subtasks are completed correctly.
- For each exercise, a detailed »sample solution« exists, sometimes with an indication to different solution paths.
- The »exercise types« used are:
- »Single Choice» ⇒ only one of the $n$ given answers is correct;
⇒ Check Box for alternative answers: ${\huge\circ}$ - »Multiple Choice« ⇒ of the $n$ given answers, between zero and $n$ answers can be correct;
⇒ Check Box for alternative answers: $\square$ - »Arithmetic Task« ⇒ numerical value query, possibly with sign;
small deviations $($usually $\pm 3\%)$ are allowed when checking real-valued results.
- We distinguish between »exercises« $($e.g. »Exercise 1.1»$)$ and »additional exercises« $($e.g. »Exercise 1.1Z«$)$.
- If you were able to solve all exercises of a chapter without any problems, we believe that you are familiar with the content of the entire chapter.
- If you have solved one exercise incorrectly, you should also work on the following, usually somewhat easier additional exercise.
$\text{Example B:}$ The $58$ exercises/additional exercises of the first book can be accessed via the link »Signal Representation: Exercises«[1].
- From there, we move on to the individual exercises, e.g. to »Exercise 1.1: Music Signals«[1]. This relatively simple exercise consists of
- one »Single Choice« ⇒ subtask (1),
- two »Multiple Choice« ⇒ subtasks (2), (3), and
- one »Arithmetic Task« with two real-valued computational queries ⇒ subtask (4).
- However, most of our exercises are not that easy. Although MediaWiki also calls an arithmetic task »quiz«, answering them is usually much more difficult than in the numerous quiz shows on TV. Because:
- There are no predetermined answers in an arithmetic task, and moreover:
- Integrals often have to be solved beforehand, such as in »Exercise 4.4: Two-dimensional Gaussian probabilty density function«[1].
- We recommend: First print the exercise ⇒ »printable version« and solve the exercise offline before checking online.
LNTwww Applets
Working with applets in a virtual environment has a similar function to laboratories in mathematical and engineering sciences face-to-face courses: Supplementing lectures and exercises through independent work by the students on the topic covered.
Starting from the »Applet«[1] button on the homepage, another click takes you to the »Alphabetic list of all HTML5/JS applets $($English language$)$«. All these twenty-four applets have the same structure:
- The »applet description page« on MediaWiki level provides all information about the theoretical background as well as the purpose and handling of the application.
- The HTML5/JavaScript program with graphical user interface takes over the parameter input and the display of the calculated diagrams and numerical results.
- The most important part of an applet is the »questionnaire«, which guides the user through the program. The user has to solve various tasks along the way:
Predict and evaluate results, optimize parameters, etc.
$\text{Example C:}$ The didactic significance of applets will be demonstrated by applet no. 10: »Eye Pattern and Worst-Case Error Probability«[1]. We will not go into the detailed explanation of the theoretical background in the »applet description page« here. Just this much: The »eye diagram« is a proven digital signal transmission tool for quantifying the influence of line dispersion on the quality characteristic »error probability«.
- By pressing »Open applet in new Tab«, the graphical program interface appears, which allows to choose from four coding options and three basic transmission pulse options. Depending on the setting, further parameter values $($as cutoff frequency, rolloff factor, ...$)$ can get determined. This means that the program offers a large number of setting options. However, not every setting brings the user a relevant learning success and even fewer lead to a so-called "aha effect".
- It was task of the program developers to formulate the »questionnaire» in the lower section $($in this example 14 exercises$)$ and the associated solutions in such a way that the learning success is as great as possible for as many users as possible. A top 10% student naturally has the opportunity to use the applet to set himself tasks that go beyond our questionnaire and thus to delve very deeply into the material presented.
- This applet serves the clarification of difficult facts. Exercise (1), for example, illustrates the step-by-step construction of the eye diagram from the binary symbol sequence for a Gaussian pulse, and Exercise (10) shows the »Overall View« of the eye diagram of a quaternary Nyquist system with rolloff factor $r_f=0.5$.
LNTwww Learning Videos
The realization of a learning video required a lot of individual steps: Writing the script and texts ⇒ Creating a set of slides by gradually adapting the content ⇒ Voicing texts and audio editing ⇒ Combining texts and images to a coherent video stream.
All our learning videos $($created between 2003–2015$)$ are only available in German language. By assuming that the users of the English version also have sufficient knowledge of German language to understand the content of the video sequences, we did not spend any extra effort in time consuming translation activities.
Please note the following points when using the learning videos:
- The link »Videos« on the homepage provides a list of all thirty-one learning videos, grouped according to the nine courses. Some videos are part for multiple courses.
- After selecting the desired learning video, a wiki description page appears with a short content description and the user interface.
- From here you can start the video in »mp4« or »ogv« format. The browser will search for the appropriate format.
- Each video part can get started by a single click and paused by another click.
- The videos can can get used in conjunction with many browsers $($Firefox, Chrome, Safari, ...$)$ as well as with smartphones and tablets. The playback speed can get changed: Firefox offers a submenu after right-clicking on the video. For the use with Google Chrome the plugin »Video Speed Controller« need to get installed.
$\text{Example D:}$ We'll take a look at the three-part learning video »Der AWGN-Kanal«[1]. Here you can see the corresponding »video description page« on MediaWiki level.
At the end of this file you will find the English title »The AWGN Channel « and the English summary:
$\text{Part 1}$ $($duration 5:59$)$: $\text{Preliminary remarks}$ $($Common channel models regarding media, operational equipment, interference/noise$)$
$\text{Part 2}$ $($duration 5:14$)$: $\text{Properties}$ $($additive, white, Gaussian distributed$)$ $\text{and characteristics}$ $($PSD, PDF, variance, standard deviation/rms$)$
$\text{Part 3}$ $($duration 6:13$)$: $\text{Calculation/simulation of BER}$ $($bit error rate$)$ $\text{and SNR}$ $($signal-to-noise ratio$)$ $\text{for the optimal binary system}$
LNTwww Glossary
Due to the fact that our e–learning project was first conceived in German and the wish for an English version came much later on, the assignment of a »formula sign« to the relevant »designation« is not quite easy, e.g. carrier frequency $f_{\rm T}$, equivalent low-pass transmitted signal $s_{\rm TP}(t)$, threshold value $E$.
The link »Glossary«[1] on the homepage can help in this context with the following alphabetically ordered entries:
- »Formula sign« ⇒ »German designation« ⇒ »English designation«
- »Formula sign« ⇒ »German designation« ⇒ »English designation«
The file »Glossary« is self-explanatory. A few explanations are available under the last menu item »Some remarks to the Glossary«.
$\text{Example E:}$ In this file you will find the following entries, among others:
- $f_{\rm T}$ ⇒ Trägerfrequenz ⇒ carrier frequency
- $s_{\rm TP}(t)$ ⇒ äquivalentes Tiefpass–Sendesignal ⇒ equivalent low-pass transmitted signal
- $ E$ ⇒ $(1)$ Schwellenwert, $(2)$ Energie ⇒ $(1)$ threshold value, $(2)$ energy
From the context, the decision for »threshold value« or »energy« should be easy.
Final Remarks
Described is our e-learning project »LNTwww«, which began in 2001 and was finished in 2024 with the completion of the English version. The intention of this article is to make this e-learning course on the subject of »Communications Engineering« a little better known in the university community.
- It is difficult to determine the exact user numbers of »LNTwww«, as there is no fixed entry point. Rather, many paths lead to our platform and you can move around it for different lengths of time.
- Based on a number of indicators $($not explained in detail here$)$, we currently expect at least twenty thousand (longer) hits per year for the German version. Nine months after completion, we are not yet able to provide a reliable number for the English version.
- The comments from our students $($in personal discussions$)$ and other users $($via e-mail$)$ were quite positive, which is why we tackled the English translation in 2020. However, it cannot be denied that we had expected euphoric rather than benevolent criticism.
Let's now take a look at the historical development of »e-learning« worldwide. A number of »virtual universities« have been established in the United States since the 1950s; the communication with users was still by post. In the early 1970s, many European universities were also involved in »computer-based learning«, including a very active research group at »TUM-LNT«, which was led by Professor Karlheinz Tröndle, the doctoral supervisor of the »LNTwww« initiators Klaus Eichin and Günter Söder. As there were no personal computers at the time, a microprocessor system first had to be developed by hardware and software.
The term »e-learning« was first mentioned in 1999 by the educational technology expert »Elliott Masie«[1] at the TechLearn conference in Disneyworld. Since 2012, leading US universities have been offering various software platforms for e-learning on the internet under the umbrella term »Massive Open Online Course« $\text{(MOOC)}$.
- The adjective »massive« is intended to indicate that there are are a lot of internet-based courses on various STEM subjects $($mathematics, computer science, natural sciences, technology$)$, that these can be used by a large number of people and that they are freely accessible to all interested parties free of charge.
- While an xMOOC is more teacher-centred, the cMOOC is more learner-centred, informal and committed to social media. In contrast to our »LNTwww«, however, registration is required for these MOOC courses.
The following MOOC data was compiled by Jürgen Veitenhansl $($2002 one of our first LNTwww students$)$; they mostly refers to the year 2022:
- The largest user numbers are reported by the Indian platform »Byju's«[1] and the Korean organisation »Khana«[1] with 150 million resp. 137 million. The e-learning provider »edx«[1], founded by professors from Harvard University and MIT $($Massachusetts Institute of Technology$)$ had around 100 million users and 2000 courses.
- The US market leader »coursera«[1] - a foundation of Stanford University - claims even higher figures with more than 100 million users and more than 7000 courses available. Five years earlier, the figures were 40 million resp. 3000 courses.
- The most important MOOCs “coursera” and “edx” have cooperation agreements with over three hundred universities worldwide, including the “Technical University of Munich”. Student groups from these universities can develop their own programs, which can be transferred to the MOOC platform after certification.
- According to the annual »coursera« reports, this platform alone achieved in 2022 a turnover of more than 500 million US dollars. The more users register for free-of-charge courses, the higher the number of those who opt for a paid course option.
- If some published market data is to be believed, the global e-learning market potential is estimated at more than 100 billion USD, i.e. more and more providers will naturally enter the market in order to obtain the largest possible share of this potential.
- If you compare the courses offered by the most important MOOC platforms »edx« and »edx«, you will see that there are many similarities to our »LNTwww» in terms of
$(1)$ basic structure, $(2)$ didactic concept, $(3)$ presentation $($theory pages, videos, audios$)$, $(4)$ exercises for performance assessment.
- We were initially quite dismayed when we recognized these analogies shortly after completing the German version. On the other hand, we felt confirmed that the concept we defined in 2001 could not be entirely wrong.
- But it should also be noted that both »coursera« and »edx« only started in 2012, when 60% of our German version was already finished. We were very surprised that »TUM-LNT« had embraced the topic of »e-learning« a decade earlier than the most important US universities.
$\text{Our conclusio:}$
- We are well aware that with our total $($in twenty-four years$)$ sixteen participating professors and doctoral students from »$\text{LNT}$«[1] $($Institute for Communications Engineering$)$ and »$\text{LÜT}$«[1] $($Professorship Line Transmission Technology$)$ and a total of about fifty students cannot achieve the same number of courses and the same number of participants as the MOOC courses »edx« and »coursera«.
- Nor their professionalism in presentation, especially with the multimedia elements. Many of our applets and videos were created in the years 2001-2010, those of the MOOC courses mostly after 2020. In between, there was a significant further development of the editing tools.
- Even from today's perspective, Gerhard Kramer's decision to tackle the English version after completing the German version was the right one, despite the effort involved, as we did not approach this step as a pure translation, but as a revision of the previously achieved. Both versions benefited from this.
- Of the 7000 MOOC courses mentioned above, some certainly deal with »Communications Engineering«. In the »TUM MOOC co-operation list«, however, there is no appropriate entry. If you do not find what you are looking for when searching other universities, we recommend »LNTwww«.
- This e-learning project provides nine online courses on the subjects of »Communications Engineering« $($grouped in another way: twelve courses of three semester hours per week each$)$. The target group of »LNTwww« are students of these or similar disciplines as well as practicing engineers and scientists.
Acknowledgement
- The authors would like to thank all professors and doctoral students who have invested in addition to their numerous tasks in research and teaching a great deal of time in the development of »LNTwww» . These people are listed by name in the »Impressum«[1], separated by book, as are the basic materials for the respective first versions.
- We would also like to thank the more than fifty students who have worked with great dedication at the »LNTwww« project between 2001 and 2023.
- The English translation $($2020–2024$)$ by working students was coordinated by Javier García Gómez, Tasnád Kernetzky and Benedikt Leible. This work was financially supported by the faculty and the university.
$\text{Gerhard Kramer}$ $\text{Günter Söder}$