10 out of 200: Serving the people – Khac-Hoang Ngo improves our telecommunication

Meet Khac-Hoang Ngo, computer scientist and one of this year’s 10 out of 200 young researchers participating in the 7th Heidelberg Laureate Forum from September 22nd – 27th, 2019.

Photo courtesy of Khac-Hoang Ngo

What are your name and nationality?
My name is Khac-Hoang Ngo. I am a Vietnamese citizen.

Where did you study and where are you currently based?
I completed my B.E. program in Electronics and Telecommunications at Vietnam National University, Hanoi in 2014 with a short internship at the National University of Singapore in 2012. I then moved to France for a M.Sc. degree in Advanced Wireless Communication Systems at CentraleSupélec, which I received in 2016. After that, I stayed in France to do a Ph.D. in Wireless Communications. I am currently living in the southern suburbs of Paris.

What is your current position?
I am a third-year Ph.D. student. I work at both CentraleSupélec, University of Paris-Saclay and Mathematical and Algorithmic Sciences Laboratory, Paris Research Center, Huawei Technologies France.

What is the focus of your research? What is your research project?
My research has been focusing on information and communication theory. In particular, I am interested in fundamental limits of and physical layer algorithms for wireless communication networks.
To quote Claude E. Shannon, ‘The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point.In a common wireless communication model, the message-carrying signal is multiplied with a channel matrix and added with noise before reaching the receiver. The channel matrix contains the electromagnetic gains between the transmission antennas and the receiving antennas. In practice, these gains are random and vary due to the relative velocity of the transmitter, the receiver, and the possible reflectors. Thus the propagation channels fade over time and frequencies. Coping with this fading effect has been one of the main challenges in designing communication systems.
Conventionally, the receiver estimates the channel gains with the help of reference symbols and then uses the channel estimate to reconstruct the transmitted signal. This is called coherent communications. On the other hand, in my Ph.D. thesis entitled Non-coherent Wireless Communications for Multi-User Multi-Antenna Systems, we consider an alternative approach consisting in designing the data transmission and reception without resorting to the hypothesis that the instantaneous state of the channel is known or estimated. This can have an advantage over coherent communications when, for example, the channel gains change very rapidly and channel estimation becomes formidable or overconsumes the communication resources. This situation is present in high mobility networks.

Why did you become a computer scientist?
I started growing curious about telecommunications since childhood when telephones emerged in my hometown. At that time, a family equipped with a fixed telephone served as a communication center for the neighborhood. It became even more interesting when mobile phones appeared. Harboring the question of how a telecommunication system works, I got engaged in mathematics and physics in school, which I thought would provide me the answer. Then I enrolled in a bachelor program in electronics and telecommunications in 2010. Back then, I just wished to become an engineer and work for a local telecommunication provider. Fortunately, my bachelor program encouraged students to learn the ropes of research and offered us a good condition to do so. I tried and became fascinated. I enjoyed stretching my mind through pondering a question and the excitement of learning or finding something new. Furthermore, I realized that I could contribute to the evolution of global communication systems through my research. This has been motivating me to pursue a Ph.D. degree and a long-term research career in this domain.

What are some of the fundamental challenges you have faced in your academic career?
I would say that is mathematics. I work with wireless communication models in which the transmitted signal, the propagation channel, and the noise are all modeled as random processes and they are linked together by algebraic operations. Thus, studying a communication system requires a solid mathematical background including probability and statistics, algebra, and analysis. It most of the time boils down to mathematical problem-solving. I got stuck in a problem many times when it reached the boundary of my mathematical knowledge, but by working out the solution (with the help of my advisors), I extended that boundary.

What do you feel are the greatest pressures facing scientists today?
I think that is the publish-or-perish pressure. Scientists are often obliged to publish quickly and continually to sustain and advance their career. This shortens the time they spend on research work, which may put incremental research over more long-term and impactful research, and put quantity over quality. Furthermore, scientists also face the pressure to have funding for their work. To get funded, scientists tend to go for hot topics and spend (a disproportionate amount of) time writing grants which nicely fit the selection criteria. This can prevent scientists from freely shaping their research and drive them away from their initial career plan.
In fact, it is not easy to decide on an appropriate motive for doing research in this money-driven world. I believe that the ultimate goal of technology research is not for the benefit of the industrial market, but to serve people and improve people’s lives. I adopted this view from Soichiro Honda, the founder of Honda Motor Company and the Honda Foundation. My favorite saying of his is ‘Whether it be learning or technology, everything in this world is nothing more than a mean to serve people. Maybe the most important thing of all is to have love for people.’

What are you doing besides research?
In my leisure time, I practice sports. I run, swim, and play soccer. I am a big fan of Manchester United Football Club. Besides, I like listening to classical music and reading. I usually read on the train to/from work. My favorite author is Haruki Murakami because I find a bit of myself in each of his main characters. I also take French evening classes.

How did you hear about the HLF and why did you apply?
My advisor, Dr. Maxime Guillaud, told me about the HLF and encouraged me to apply. I took a look at the program and got impressed by the opportunity that it offers the participants.
In 2015, I joined hands to organize a similar networking event for young engineers and scientists in Asia – the Honda Y-E-S Forum. It was a venue to discuss the issues in the region and the role that science and technology should fulfill in resolving them. During the preparation and organization of this forum, I met other young people from Japan, Vietnam, and other developing countries in Asia. We had fruitful discussions and exchanged ideas. I also had the opportunity to attend the Honda Prize Ceremonies and met the laureates. I admired them for the impact of their works on improving human life through technology. It was indeed a great honor and very inspiring to meet and talk to them. I found the HLF a similar source of inspiration, so I applied.

What do you expect from this meeting?
I expect to meet, learn from and get inspired by great minds who made a high impact in the world through their research. I have looked into their profiles and was impressed by their contributions.
Furthermore, I desire to meet other young researchers to discuss, exchange ideas, and get inspired by them as well. I have seen the interviews of the past participants and got impressed by their enthusiasm and diverse backgrounds and perspectives. Some of them are also from developing countries who have a strong willingness to make a change in their country. There were also people with disabilities who keep pursuing their passion and want to encourage others of the same circumstance to do so. I wish to see people with great passion like them at the HLF this year.
Last but not least, I want to broaden my knowledge through the lectures at the HLF.

Which laureates present at the forum would you really like to talk to and what do you want to ask them?
In general, I want to ask the laureates a question that I have been harboring: How to identify the important problems and come up with the “big idea” without being stuck in incremental research that has only limited impact?
In particular, I am looking forward to attending a lecture of Prof. Joseph Sifakis on system design in order to gain insights into the problem of communication network design.

Who were your most important mentors and what lessons did they pass on to you?
All my advisors since my bachelor have been my important mentors in research and self-development. I treasure every lesson I got from them. In particular, my bachelor advisor, Prof. Linh-Trung Nguyen, passed on to me the lesson: never avoid the difficulty in research, keep going straight and raze it. When I started working with him, I usually switched to alternative ways when I got stuck solving a problem, which admittedly often carried me away from the initial direction. His advice helped me to be more consistent. My academic Ph.D. advisor, Prof. Sheng Yang, taught me to try to see the essence of a problem, often through a simple but comprehensive enough example, without getting lost in the maze of details. My industrial Ph.D. advisor, Dr. Maxime Guillaud, showed me the benefit of scientific discussion and building collaboration among individuals with diverse but complementary expertise and perspectives.

What are flexible wireless networks and how could developing countries especially benefit from them?
In my vision, flexible wireless networks are ones which can be self-organized under less stringent constraints. Such a network should allow heterogeneous network entities to cooperate in order to assist each other in retrieving the needed information. In addition, the network algorithms should be implemented distributively such that there is no need for an expensive central processing unit and new devices can be easily admitted into the system. Furthermore, the network functions can be flexibly defined in software such that any network establishment or modification would not require a substantial infrastructure change.
My desire for a flexible network grows from observing the situation in developing countries. These countries do not have a communication infrastructure as good as in developed countries and face some typical challenges. For example, my home country Vietnam is high ranked globally for the strong effects of shocks and natural disasters related to climate change. We are hit by more than ten typhoons each year (16 in 2017), which flood many towns for weeks. On top of that, quick urbanization results in the fact that more than 35% of the population is living in urban areas. In the case of disaster, especially if the electricity is idle, a flexible self-organized communication network, for example between unmanned aerial vehicles, would greatly facilitate the salvage.

Jens-Steffen Scherer

Jens-Steffen Scherer is a neuroscientist, science communicator, and moderator. Besides pursuing his Ph.D. at the University of Oldenburg, he works for the National Institute for Science Communication (NaWik) and the Südwestrundfunk (SWR). In 2018 Jens-Steffen won the 8th Science Slam of Oldenburg. Jens-Steffen Scherer ist Neurowissenschaftler, Wissenschaftskommunikator und Moderator. Neben seiner Promotion an der Universität Oldenburg arbeitet er als freier Autor für den Südwestrundfunk (SWR) und beim Nationalen Institut für Wissenschaftskommunikation (NaWik). 2018 gewann Jens-Steffen den 8. Oldenburger Science Slam.

2 comments

  1. I consider the transmission of a common message from a transmitter to two receivers over a broadcast channel, also called a multicast channel in this case. The two receivers are allowed to cooperate with each other in full-duplex over non-orthogonal cooperation links. We investigate the information-theoretic upper and lower bounds on the broadcast.
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