Speaker: Khac-Hoang Ngo (Chalmers University of Technology)
Place: Amphi Chappe/Lamarr, 6 avenue des arts, La Doua Campus
Title: Unsourced Multiple Access: An Information-Theoretic Analysis
Abstract: The drastic growth of the number of connected devices gives rise to the Internet of Things (IoT). Massive IoT connectivity targets a large number of low-cost, battery-limited, narrowband devices—meters, sensors, trackers, wearables—that transmit small data volumes in a sporadic and uncoordinated manner. These key features are captured by the unsourced multiple access (UMA) model proposed by Polyanskiy (2017), where all users transmit their messages using the same codebook and the decoder returns an unordered list of messages. In this talk, we introduce the UMA framework and Polyanskiy’s random-coding achievability bound for the Gaussian UMA channel. We then extend this bound to the case of random and unknown number of active users, thus fully account for the random user activity. Finally, we investigate a setting where, on top of the standard UMA messages, the users transmit a common alarm message that needs to be decoded with higher reliability; we thereby study the coexistence of massive and critical IoT.
Bio: Khac-Hoang Ngo (https://khachoang1412.github.io/) received the B.Eng. degree (Hons.) in electronics and telecommunications from Vietnam National University, Hanoi, Vietnam, in 2014; and the M.Sc. degree (Hons.) and Ph.D. degree in wireless communications from CentraleSupélec, Paris-Saclay University, France, in 2016 and 2020, respectively. His Ph.D. thesis was also realized at Paris Research Center, Huawei Technologies France. Since September 2020, he has been a postdoc at Chalmers University of Technology, Sweden under a project funded by the MSCA Individual Fellowship. His research interests include wireless communications and information theory, with an emphasis on massive random access, edge computing, MIMO, noncoherent communications, coded caching, and network coding. He received the Honda Award for Young Engineers and Scientists in Vietnam in 2013 and the “Signal, Image & Vision Ph.D. Thesis Prize” by Club EEA, GRETSI and GdR-ISIS, France, in 2021.