Date: 29 November 2024, Friday
Time: 4:30pm
Venue: CD 634, The Hong Kong Polytechnic University
Zoom Meeting ID: 820 0818 3929
Password: 175578
Speaker: Prof. Fan Liu, Southeast University, Nanjing
Uncovering the Iceberg in the Sea: Fundamentals of Modulation and Pulse Shaping Design for Random ISAC Signals
Prof. Fan Liu, Southeast University, Nanjing
Abstract:Integrated Sensing and Communications (ISAC) is expected to play a pivotal role in future 6G networks. To maximize time-frequency resource utilization, 6G ISAC systems must exploit data payload signals, that are inherently random, for both communication and sensing tasks. In this talk, we provide a comprehensive analysis of the sensing performance of such communication-centric ISAC signals, with a focus on modulation and pulse shaping design to reshape the statistical properties of their auto-correlation functions (ACFs), thereby improving the target ranging performance. We derive a closed-form expression for the expectation of the squared ACF of random ISAC signals, considering arbitrary modulation bases and constellation mappings within the Nyquist pulse shaping framework. We will first theoretically prove the optimality of OFDM as a modulation basis for random ISAC signals, in the sense that it achieves the lowest ranging sidelobe level among all orthogonal communication waveforms. Then, we show that the ACF of pulse-shaped ISAC signal may be metaphorically described as an iceberg hidden in the sea structure, where the iceberg represents the squared mean of the ACF of random ISAC signals, that is determined by the pulse shaping filter, and the sea level characterizes the corresponding variance, and account for the randomness of the data payload. Building on these insights, we propose a novel Nyquist pulse shaping design to enhance the sensing performance of random ISAC signals. Finally, we conclude the talk by identifying a number of future research directions.
Speaker’s Bio: Fan Liu (Senior Member, IEEE) is currently a Professor with the School of Information Science and Engineering, Southeast University, Nanjing, China. Prior to that, he was an Assistant Professor with the Southern University of Science and Technology, Shenzhen, China, from 2020 to 2024. Dr. Liu’s research interests lie in the general area of signal processing and wireless communications, and in particular in the area of Integrated Sensing and Communications (ISAC). He was listed among the 2023 Elsevier Highly-Cited Chinese Researchers. He was the recipient of the 2024 IEEE ComSoc Asia-Pacific Outstanding Paper Award, 2023 IEEE ComSoc Stephan O. Rice Prize, 2021 IEEE SPS Young Author Best Paper Award, and 2023 IEEE ICC Best Paper Award. He is the founding Academic Chair of the IEEE ComSoc ISAC Emerging Technology Initiative (ISAC-ETI), an elected member of the IEEE SPS Sensor Array and Multichannel Technical Committee (SAM-TC), a founding member of the IEEE SPS ISAC Technical Working Group (ISAC-TWG). He also serves as an Associate Editor of the IEEE TCOM, IEEE TMC, and IEEE OJSP, a Guest Editor of the IEEE JSAC, IEEE WCM, and IEEE VTM, and was an Associate Editor of the IEEE COMML (2020-2024).
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