Double-side delay alignment modulation for multi-user millimeter wave and terahertz communications ✩,✩✩

Xingwei Wang; Haiquan Lu; Jieni Zhang; Yong Zeng

doi:10.1016/j.dcan.2025.04.002

›› 2026, Vol. 12 ›› Issue (1) :11 -24. DOI: 10.1016/j.dcan.2025.04.002

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Double-side delay alignment modulation for multi-user millimeter wave and terahertz communications ^✩,✩✩

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^a National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China

^b Purple Mountain Laboratories, Nanjing 211111, China

^* National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China. E-mail address: yong_zeng@seu.edu.cn (Y. Zeng).

Xingwei Wang received the B.E. degree in communication engineering from Jilin Uni-versity, Jilin, China, in 2014, the M.S. degree in communication and information systems from Shanghai University, Shanghai, China, in 2020, and the Ph.D. degree at the National Mobile Communications Research Laboratory, Southeast University, Nanjing, China, in 2025. She worked as a transmission and power systems maintenance engineer at China Unicom from 2014 to 2017, and communication algorithm engineer at UNISOC in 2021. Her research interests include massive MIMO and delay alignment modulation.

Haiquan Lu received the B.S. degree in communication engineering from Yangzhou University, Yangzhou, China, in 2016, the M.S. degree in signal and information pro-cessing from Nanjing University of Posts and Telecommunications, Nanjing, China, in 2019, and the Ph.D. degree at the National Mobile Communications Research Labora-tory, Southeast University, Nanjing, China, in 2024. His research interests include intel-ligent reflecting surface-aided communications and extremely large-scale multiple-input multiple-output (XL-MIMO) communications. He was a recipient of the Best Paper Award from the IEEE International Conference on Communications (ICC) in 2021.

Jieni Zhang received the B.S. degree from Nanjing University of Posts and Telecom-munications in 2023. She is currently pursuing the M.S. degree with the National Mobile Communications Research Laboratory, Southeast University, Nanjing, China. Her research interests include extremely large-scale MIMO and waveform design.

Yong Zeng (Fellow, IEEE) is a Chief Young Professor with the National Mobile Com-munications Research Laboratory, Southeast University, China, and also with the Purple Mountain Laboratories, Nanjing, China. He received the Bachelor of Engineering (First-Class Honours) and Ph.D. degrees from Nanyang Technological University, Singapore. From 2013 to 2018, he was a Research Fellow and Senior Research Fellow at the De-partment of Electrical and Computer Engineering, National University of Singapore. From 2018 to 2019, he was a Lecturer at the School of Electrical and Information Engineer-ing, the University of Sydney, Australia. Prof. Zeng was listed as Highly Cited Researcher by Clarivate Analytics for seven consecutive years (2019-2025). He is the recipient of the Australia Research Council (ARC) Discovery Early Career Researcher Award (DECRA), 2020 & 2024 IEEE Marconi Prize Paper Award in Wireless Communications, 2018 IEEE Communications Society Asia-Pacific Outstanding Young Researcher Award, 2020 & 2017 IEEE Communications Society Heinrich Hertz Prize Paper Award, 2021 IEEE ICC Best Pa-per Award, and 2021 China Communications Best Paper Award. He serves/served as an Associate Editor for IEEE Transactions on Communications, IEEE Transactions on Mobile Computing, IEEE Communications Letters and IEEE Open Journal of Vehicular Technol-ogy, Leading Guest Editor for IEEE Wireless Communications on “Integrating UAVs into 5G and Beyond” and China Communications on “Network-Connected UAV Communication-s”. He is the Symposium Chair for IEEE Globecom 2021 Track on Aerial Communications, the workshop co-chair for ICC 2018-2023 workshop on UAV communications, the tuto-rial speaker for Globecom 2018/2019 and ICC 2019 tutorials on UAV communications. Prof. Zeng proposed the concept of channel knowledge map (CKM) and the transmission method of delay-Doppler alignment modulation (DDAM). He has published more than 200 papers, which have been cited by more than 34,000 times based on Google Scholar. Prof. Zeng was elevated to IEEE Fellow “for contributions to unmanned aerial vehicle commu-nications and wireless power transfer”.

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Abstract

Delay Alignment Modulation (DAM) is an innovative broadband modulation technique well-suited for millimeter Wave (mmWave) and Terahertz (THz) massive Multiple-Input Multiple-Output (MIMO) communication systems. Leveraging the high spatial resolution and sparsity of multi-path channels, DAM eﬀectively mitigates Inter-Symbol Interference (ISI) by aligning all multi-path components through a combination of delay pre-compensation (or post-compensation) and path-based beamforming. As such, ISI is eliminated while preserving multi-path power gains. In this paper, we investigate multi-user double-side DAM, which incorporates both delay pre-compensation at the transmitter and post-compensation at the receiver, in contrast to prior works that primarily focus on single-side DAM with only delay pre-compensation. Firstly, we derive the constraint on the number of introduced delays and formulate the corresponding delay pre/post-compensation vectors tailored for multi-user double-side DAM, given a specific number of delay compensations. Furthermore, we demonstrate that when the number of Base Stations (BSs)/User Equipment (UE) antennas is suﬃciently large, single-side DAM—where delay compensation is performed only at the BS/UE—is preferable to double-side DAM, since the former results in less ISI to be spatially eliminated. Next, we propose two low-complexity path-based beamforming strategies based on the eigen-beamforming transmission and ISI-Zero Forcing (ZF), respectively. On this basis, we further analyze the achievable sum rates. Simulation results verify that with a suﬃciently large number of BS/UE antennas, single-side DAM is adequate for ISI elimination. Moreover, compared to the benchmarking scheme of Orthogonal Frequency Division Multiplexing (OFDM), multi-user BS-side DAM achieves higher spectral eﬃciency and lower Peak-to-Average Power Ratio (PAPR).

Keywords

Delay alignment modulation / Delay pre-compensation / Delay post-compensation / Path-based beamforming / Fractional channel delay

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Xingwei Wang, Haiquan Lu, Jieni Zhang, Yong Zeng. Double-side delay alignment modulation for multi-user millimeter wave and terahertz communications ^✩,✩✩. , 2026, 12(1): 11-24 DOI:10.1016/j.dcan.2025.04.002

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CRediT authorship contribution statement

Xingwei Wang: Writing-review & editing, Writing-original draft, Validation, Methodology, Conceptualization. Haiquan Lu: Writing-re-view & editing. Jieni Zhang: Writing-review & editing. Yong Zeng: Writing-review & editing.

Declaration of competing interest

All authors disclosed no relevant relationships.

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