Jekyll2024-01-10T07:17:34-08:00https://khachoang1412.github.io/feed.xmlHomePh.D. in Wireless Communications and Information TheoryKhac-Hoang NgoOur new paper *Unsourced Multiple Access With Random User Activity*2022-02-16T00:00:00-08:002022-02-16T00:00:00-08:00https://khachoang1412.github.io/news-post/UMA-random-user-activity<p><img src="/images/UMA_random_user_activity.PNG" alt="UMA_random_user_activity" style="width:600px; float: center;" og:image="https://khachoang1412.github.io/images/UMA_random_user_activity.PNG" /></p>
<p>Unsourced Multiple Access (UMA) where all users employ a common codebook and the receiver decodes up to a permutation of messages is a relevant framework for the massive uncoordinated random access scenario in the Internet of Things (IoT). The proposal of UMA by Polyanskiy (2017) has triggered an active area of research in devising coding schemes that approach the achievable energy efficiency bound derived therein. However, it was assumed that the number of active users is fixed and known a priori to the receiver, which is typically farfetched in practical IoT scenarios due to time-varying and grant-free user activity.</p>
<p>In our recent work entitled “Unsourced Multiple Access With Random User Activity” submitted to IEEE Transactions on Information Theory, we extend Polyanskiy’s seminal work to the case where the number of active users is random and unknown a priori. We define a random-access code accounting for both misdetection (MD) and false alarm (FA), and derive a random-coding achievability bound for the Gaussian multiple-access channel. Numerical results suggest that, when the target MD and FA probabilities are high, it is effective to estimate the number of active users, then treat this estimate as the true value, and use a coding scheme that performs well for the case of known number of active users. However, this approach becomes energy inefficient when the requirements on MD and FA probabilities are stringent due to the active-user estimation bottleneck.</p>
<p>Our paper can be found here: <a href="https://arxiv.org/pdf/2202.06365.pdf">https://arxiv.org/pdf/2202.06365.pdf</a>.</p>
<p>We also make the simulation code available at: <a href="https://github.com/khachoang1412/UMA_random_user_activity">https://github.com/khachoang1412/UMA_random_user_activity</a>.</p>
<p>A presentation of a short version in ISIT 2021 can be seen below.</p>
<p><a href="https://www.youtube.com/watch?v=6Vr5ZKZzIjw"><img src="https://img.youtube.com/vi/6Vr5ZKZzIjw/0.jpg" alt="Massive Uncoordinated Access With Random User Activity" /></a></p>
<p>This work was jointly done with Alejandro Lancho, Giuseppe Durisi, and Alexandre Graell i Amat, under my MSCA project “LANTERN: Low-lAtency aNd privaTe Edge computing in Random-access Networks”.</p>Khac-Hoang NgoOur paper *Unsourced Multiple Access With Random User Activity* has been submitted to IEEE Transactions on Information Theory.Matlab routines for our paper *Age of Information in Prioritized Random Access*2022-01-18T00:00:00-08:002022-01-18T00:00:00-08:00https://khachoang1412.github.io/news-post/matlab-AoI-Asilomar-paper<p><img src="/images/AoI_Asilomar.PNG" alt="AoI_Asilomar" style="width:600px; float: center;" /></p>
<p>The matlab numerical routines in our paper:</p>
<p>K.-H. Ngo, G. Durisi, and A. Graell i Amat, “Age of information in prioritized random access,” in 55th Asilomar Conference on Signals, Systems, and Computers, CA, USA, Oct. 2021.</p>
<p>are now available at <a href="https://github.com/khachoang1412/AoI_prioritized_random_access">https://github.com/khachoang1412/AoI_prioritized_random_access</a>.</p>
<p>Please, cite the aforementioned paper if you use this code.</p>Khac-Hoang NgoMatlab numerical routines for our paper *Age of Information in Prioritized Random Access* presented in Asilomar 2021.Recorded videos of my presentations in 20212022-01-05T00:00:00-08:002022-01-05T00:00:00-08:00https://khachoang1412.github.io/news-post/presentation-video-2021<p>In 2021, I have presented my research in several conferences. Due to the covid-19 pandemic, all of these conferences turned virtual/hybrid. On the bright side, this was a chance to have my presentations recorded and ready to be shared afterward. Please find them below.</p>
<hr />
<p>A short presentation of my Ph.D. thesis “Noncoherent Wireless Communications: Fundamental Limits and System Design”:</p>
<p><a href="https://www.youtube.com/watch?v=EbpBFH7-kpY"><img src="https://img.youtube.com/vi/EbpBFH7-kpY/0.jpg" alt="Noncoherent Wireless Communications: Fundamental Limits and System Design" /></a></p>
<hr />
<p>K.-H. Ngo, A. Lancho, G. Durisi and A. Graell i Amat, “Massive Uncoordinated Access With Random User Activity,” <em>IEEE International Symposium on Information Theory (ISIT),</em> 2021, pp. 3014-3019. <a href="https://arxiv.org/pdf/2103.09721.pdf">PDF</a></p>
<p><a href="https://www.youtube.com/watch?v=6Vr5ZKZzIjw"><img src="https://img.youtube.com/vi/6Vr5ZKZzIjw/0.jpg" alt="Massive Uncoordinated Access With Random User Activity" /></a></p>
<hr />
<p>K.-H. Ngo, G. Durisi, and A. Graell i Amat, “Age of information in prioritized random access,” <em>55st Asilomar Conference on Signals, Systems, and Computers,</em> CA, USA, Oct. 2021. <a href="https://arxiv.org/pdf/2112.01182.pdf">PDF</a></p>
<p><a href="https://www.youtube.com/watch?v=xtyOsdLLIso"><img src="https://img.youtube.com/vi/xtyOsdLLIso/0.jpg" alt="Age of information in prioritized random access" /></a></p>
<hr />
<p>K.-H. Ngo, N. T. Nguyen, T. Q. Dinh, T. -M. Hoang and M. Juntti, “Low-Latency and Secure Computation Offloading Assisted by Hybrid Relay-Reflecting Intelligent Surface,” <em>International Conference on Advanced Technologies for Communications (ATC),</em> 2021, pp. 306-311. <a href="https://arxiv.org/pdf/2109.01335.pdf">PDF</a></p>
<p><a href="https://www.youtube.com/watch?v=B1Y-CbGewAw"><img src="https://img.youtube.com/vi/B1Y-CbGewAw/0.jpg" alt="Low-Latency and Secure Computation Offloading Assisted by Hybrid Relay-Reflecting Intelligent Surface" /></a></p>
<hr />
<p>K.-H. Ngo and S. Yang, “A Generalized Gaussian Model for Wireless Communications,” <em>IEEE International Symposium on Information Theory (ISIT),</em> 2021, pp. 3237-3242. <a href="https://research.chalmers.se/publication/522211/file/522211_AdditionalFile_2ad4209d.pdf">PDF</a></p>
<p><a href="https://www.youtube.com/watch?v=8ViFwzyItFc"><img src="https://img.youtube.com/vi/8ViFwzyItFc/0.jpg" alt="A Generalized Gaussian Model for Wireless Communications" /></a></p>
<hr />
<p>K.-H. Ngo, F. Zhang, S. Yang and A. Nosratinia, “Two-User MIMO Broadcast Channel with Transmit Correlation Diversity: Achievable Rate Regions,” <em>2021 IEEE Information Theory Workshop (ITW),</em> 2021.</p>
<p><a href="https://www.youtube.com/watch?v=IrTPDHCO9O4"><img src="https://img.youtube.com/vi/IrTPDHCO9O4/0.jpg" alt="Two-User MIMO Broadcast Channel with Transmit Correlation Diversity: Achievable Rate Regions" /></a></p>
<hr />
<p>K.-H. Ngo, S. Yang, and M. Guillaud, “The Optimal DoF for the Noncoherent MIMO Channel with Generic Block Fading,” <em>IEEE Information Theory Workshop (ITW)</em>, 2021. <a href="https://arxiv.org/pdf/2009.11556.pdf">PDF</a></p>
<p><a href="https://www.youtube.com/watch?v=4gbvQplQITA"><img src="https://img.youtube.com/vi/4gbvQplQITA/0.jpg" alt="The Optimal DoF for the Noncoherent MIMO Channel with Generic Block Fading" /></a></p>
<hr />
<p>K.-H. Ngo, S. Yang, M. Guillaud and A. Decurninge, “Noncoherent MIMO Multiple-Access Channels: A Joint Constellation Design,” <em>IEEE Information Theory Workshop (ITW),</em> 2021. <a href="https://arxiv.org/pdf/2009.11548.pdf">Extended PDF</a></p>
<p><a href="https://www.youtube.com/watch?v=owQ7qkDbH3g"><img src="https://img.youtube.com/vi/owQ7qkDbH3g/0.jpg" alt="Noncoherent MIMO Multiple-Access Channels: A Joint Constellation Design" /></a></p>Khac-Hoang NgoA collection of recorded videos of my presentations in several conferences in 2021Thesis prize awarded by CentraleSupélec Foundation2021-12-01T00:00:00-08:002021-12-01T00:00:00-08:00https://khachoang1412.github.io/news-post/thesis-prize-impact-science<p><img src="/images/impact_science.png" alt="impact_science" style="width:600px; float: center;" /></p>
<p>I am glad and honored to receive the second prize in Impact Science catergory by CentraleSupélec Foundation for my Ph.D. thesis on noncoherent wireless communications.
These prizes are awarded to best theses defended from Jan. 2020 to Oct. 2021 in CentraleSupélec, Paris-Saclay University (all disciplines included).</p>
<p>Special thanks go to my Ph.D. supervisors: <a href="https://l2s.centralesupelec.fr/en/u/yang-sheng/">Prof. Sheng Yang</a> and <a href="http://research.mguillaud.net/">Dr. Maxime Guillaud</a>.</p>
<p>More about the prize <a href="https://www.fondation-centralesupelec.fr/ceremonie-de-remise-des-prix-de-these-2021-de-la-fondation-centralesupelec/">here</a>.</p>
<p>My thesis manuscript can be found <a href="https://tel.archives-ouvertes.fr/tel-02900446/document">here</a>.</p>Khac-Hoang NgoI am awarded the second prize in Impact Science catergory by CentraleSupélec Foundation for my Ph.D. thesisBest paper award at ATC 20212021-10-13T00:00:00-07:002021-10-13T00:00:00-07:00https://khachoang1412.github.io/news-post/best-paper-ATC<p><img src="/images/HHRIS.PNG" alt="HRRIS" style="width:500px; float: center;" /></p>
<p>Our paper entitled <strong>“Low-Latency and Secure Computation Offloading Assisted by Hybrid Relay-Reflecting Intelligent Surface”</strong> receives the Best Paper Award at the <a href="https://atc-conf.org/">2021 International Conference On Advanced Technologies For Communications (ATC)</a>, HCM City, Vietnam.</p>
<p>This is a joint work with Nhan Thanh Nguyen and Markku Juntti (University of Oulu, Finland), Thinh Quang Dinh (Fossil Vietnam), and Trong-Minh Hoang (Posts and Telecommunications
Institute of Technology, Vietnam).</p>
<p><strong>Abstract</strong>:
Recently, the hybrid relay-reflecting intelligent surface (HRRIS) has been introduced as a spectral- and energyefficient architecture to assist wireless communication systems. In the HRRIS, a single or few active relay elements are deployed along with a large number of passive reflecting elements, allowing it to not only reflect but also amplify the incident signals. In this work, we investigate the potential of the HRRIS in aiding the computation offloading in a single-user mobile edge computing system. The objective is to minimize the offloading latency while ensuring the secrecy of user data against a malicious eavesdropper. We develop efficient solutions to this latency minimization problem based on alternating optimization. Through numerical results, we show that the deployment of the HRRIS can result in a considerable reduction in latency. Furthermore, the latency
reduction gain offered by the HRRIS is much more significant than that of the conventional reconfigurable intelligent surface (RIS).</p>
<p>The paper can be found <a href="https://arxiv.org/pdf/2109.01335.pdf">here.</a></p>Khac-Hoang NgoOur paper got the Best Paper Award at the [2021 International Conference On Advanced Technologies For Communications (ATC)](https://atc-conf.org/), HCM City, VietnamMy MSCA project LANTERN starts2021-10-01T00:00:00-07:002021-10-01T00:00:00-07:00https://khachoang1412.github.io/news-post/lantern-starts<p><img src="/images/lantern_model.PNG" alt="LANTERN" style="width:500px; float: center;" /></p>
<p>On Oct 01, 2021, I start my MSCA project <strong>“LANTERN: Low-latency and private edge computing in random-access networks”</strong>. Details about the project: <a href="https://europa.eu/!MNF4Vm">https://europa.eu/!MNF4Vm</a>.
I will spend two more years at Chalmers working under the supervision of Prof. <a href="https://gdurisi.github.io/">Giuseppe Durisi</a> and Prof. <a href="https://sites.google.com/site/agraellamat/">Alexandre Graell i Amat</a>.</p>
<p>Excited to learn, grow and contribute in the coming two years!</p>
<p><strong>Project description</strong></p>
<p>We are living in a world where connected devices outnumber human population, and this trend keeps growing: around 24.6 billion connections are forecasted in 2025—more than three times the estimated population. This gives rise to the Internet of Things (IoT) in which virtually all devices are interconnected and continuously share data. The IoT is a key enabler for a host of applications, such as intelligent transportation systems, smart cities, and smart grids. Thus it promises to transform the way we live. To realize the IoT, it is crucial and timely to develop a communication and computation infrastructure that is able to support the processing of a vast amount of time-sensitive data, for which a centralized computation is inadequate. Edge computing has emerged as a novel paradigm to guarantee very low-latency and high-bandwidth computing services. It involves moving the computation power from the cloud to where data is generated, by pooling the available resources at the network edge.</p>
<p>In this project, we investigate how low-latency and private edge computing protocols can be developed in wireless random-access networks. Relying on tools from information theory and coding theory, we will tackle the two following challenging objectives: i) to establish a foundation for privacy and reliability in latency-critical, multi-client and multi-server edge computing in random-access networks; and ii) to devise resilient coding schemes together with energy-efficient and scalable wireless random-access protocols to achieve low latency and preserve privacy in distributed edge computing. The results of this project will help paving the way to the full realization of the IoT in the near future.</p>Khac-Hoang NgoI start my MSCA project **LANTERN: Low-latency and private edge computing in random-access networks**