Publications

Channel estimation via GAMP for millimeter wave hybrid massive MIMO systems

Published in Frequenz, 2022

In this paper, we study the channel estimation problem for the millimeter wave (mm-wave) hybrid massive multiple-input multiple-output (MIMO) system. Based on the sparsity exhibited by the mm-wave channel in the angular domain, we select a portion of the beams that contribute to the communication process from the beam- space. Then, the generalized approximate message passing (GAMP) is employed to estimate the corresponding channel parameters.

Recommended citation: Q. Huang and A. Hu, "Channel estimation via GAMP for millimeter wave hybrid massive MIMO systems," Frequenz, Feb. 2022.

Link to code: https://github.com/anzhonghu/Channel-Estimation-via-GAMP-for-Millimeter-Wave-Hybrid-Massive-MIMO-Systems

Pattern search and compressed sensing based phase noise and channel estimation for mmWave massive MIMO-OFDM systems

Published in Frequenz, 2022

In this paper, we investigate phase noise and channel estimation. Based on angular domain channel sparsity, we employ OMP for channel estimation；Based on the frequency domain phase noise, we reduce the length of phase noise for estimation, and we propose to employ pattern search. We also propose a time variant training method.

Recommended citation: Y. Qiao, A. Hu, and X. Chen, "Pattern search and compressed sensing based phase noise and channel estimation for mmWave massive MIMO-OFDM systems," Signal Process., vol. 205, Apr. 2023.

Link to code: https://github.com/anzhonghu/Pattern-search-and-compressed-sensing-based-phase-noise-and-channel-estimation

Wideband Millimeter-wave OFDM Uplink with Hybrid Receiving

Published in IEEE ICEICT 2021, 2021

In this paper, we study millimeter-wave orthogonal frequency division multiplexing uplink transmission with a wide bandwidth and hybrid receiving. By considering the spatial- and frequency-wideband effects in the channel model, the spectral efficiency of the system is analyzed. The analysis and the simulation results show the beam squint effect caused by the wideband effects. Moreover, the impacts of the bandwidth and the number of subcarriers on the beam squint effect are revealed.

Recommended citation: Y. Li and A. Hu, "Wideband millimeter-wave OFDM uplink with hybrid receiving," in Proc. IEEE 4th Int. Conf. Electron. Inform. and Commun. Tech., Xian, China, Aug. 2021, pp. 735-739.

Link to code: https://github.com/anzhonghu/Wideband-Millimeter-wave-OFDM-Uplink-with-Hybrid-Receiving

Position Aided Beam Learning for Initial Access in mmWave MIMO Cellular Networks

Published in IEEE Syst. J., 2020

In this paper, beam learning based on position information (PI) about mobile station positions in the initial access (IA) of millimeter wave (mmWave) multiple input multiple output cellular networks is investigated. Based on the sparse scattering of mmWave signals, the serving area is partitioned into smaller areas and the beams are learned for each small area. Moreover, the number of learned beams is restricted and fixed after learning. Thus, the impact of position inaccuracy and blockage can be mostly mitigated and the IA delay is short in each successful IA.

Recommended citation: A. Hu and J. He, "Position aided beam learning for initial access in mmWave MIMO cellular networks," IEEE Syst. J., vol. 16, no. 1, pp. 1103-1113, Mar. 2022.

Link to code: https://github.com/anzhonghu/Position-Aided-Beam-Learning-for-Initial-Access

Antenna tilt optimization for multi-cell massive multiple-input multiple-output (MIMO) systems with two tilts

Published in Frequenz, 2020

In this paper, we study the optimization of two tilt angles corresponding to two antenna arrays in each base station (BS) of a massive multiple-input multiple-output system. By maximizing the lower bound or the limit throughput, the two antenna tilt angles are optimized.

Recommended citation: D. Chu and A. Hu, "Antenna tilt optimization for multi-cell massive multiple-input multiple-output (MIMO) systems with two tilts," Frequenz, vol. 74, no. 9-10, pp. 359–368, Sep. 2020.

Link to code: https://github.com/anzhonghu/Antenna-tilt-optimization-for-multi-cell-massive-MIMO-systems-with-two-tilts

Pilot design and allocation for multi-cell massive MIMO systems with two-tier receiving

Published in IEEE Trans. Veh. Technol., 2020

This paper investigates pilot design and allocation in multi-cell massive multiple-input multiple-output systems with two-tier receiving. Based on the analysis of the signal-to-interference-plus-noise ratio (SINR), the discrete Fourier transform vectors are employed in designing pilots with various correlation values, and the pilots are allocated to the cells in a greedy way with the object of maximizing the sum rate upper bound.

Recommended citation: A. Hu, "Pilot design and allocation for multi-cell massive MIMO systems with two-tier receiving," IEEE Trans. Veh. Technol., vol. 69, no. 7, pp. 7443–7457, Jul. 2020.

Link to code: https://github.com/anzhonghu/Pilot-Design-and-Allocation-for-Multi-Cell-Massive-MIMO-Systems-with-Two-Tier-Receiving

Spatial overlapping index based joint beam selection for millimeter-wave multiuser MIMO systems

Published in Signal Process., 2020

In this paper, beam selection for millimeter-wave multiuser multi-input multi-output (MIMO) systems that employ zero-forcing based analog-digital hybrid processing is investigated. By first assuming full channel state information, the problem of joint beam selection is formulated and the concept of spatial overlapping index (SOI) is proposed to deal with the strong interference imposed by the MSs which share beams with some other MSs.

Recommended citation: A. Hu and S. Yang, "Spatial overlapping index based joint beam selection for millimeter-wave multiuser MIMO systems," Signal Process., vol. 167, pp. 1-10, Jan. 2020.

Link to code: https://github.com/anzhonghu/Spatial-overlapping-index-based-joint-beam-selection-for-millimeter-wave-multiuser-MIMO-systems

All-digital massive MIMO uplink and downlink rates under a fronthaul constraint

Published in Proc. 2019 IEEE Asilomar Conf. Signals, Syst., and Comput., 2019

We characterize the rate achievable in a bidirectional quasi-static link where several user equipments communicate with a massive multiple-input multiple-output base station (BS).

Recommended citation: Y. Ettefagh, S. Jacobsson, A. Hu, G. Durisi, and C. Studer, "All-digital massive MIMO uplink and downlink rates under a fronthaul constraint," in Proc. 2019 IEEE Asilomar Conf. Signals, Syst., and Comput., Pacific Grove, USA, pp. 416-420, Nov. 2019.

Grouping optimization based hybrid beamforming for multiuser MmWave massive MIMO systems

Published in Proc. 2019 IEEE 2nd Int. Conf. Comput. Commun. Eng. Technology(CCET), 2019

In millimeter-wave massive multiple input multiple output multiuser systems, inter-user interference becomes a major factor limiting system capacity. The premise of increasing system capacity is to minimize inter-user interference on the basis of ensuring large receiving power. In response to this situation, this paper proposes a low complexity grouping optimization based hybrid beamforming (HBF) algorithm.

Recommended citation: Y. Ding and A. Hu, "Grouping optimization based hybrid beamforming for multiuser MmWave massive MIMO systems," in Proc. 2019 IEEE 2nd Int. Conf. Comput. Commun. Eng. Technology(CCET), Beijing, China, pp. 203-207, Aug. 2019.

Link to code: https://github.com/anzhonghu/Grouping-optimization-based-hybrid-beamforming-for-multiuser-MmWave-massive-MIMO-systems

User scheduling for capacity-Jain’s fairness tradeoff in millimeter-wave MIMO systems

Published in Signal Process., 2019

This paper investigates user scheduling in millimeter-wave multiple-input multiple-output systems that can achieve a tradeoff between capacity and Jain’s fairness index.

Recommended citation: A. Hu, "User scheduling for capacity-Jain’s fairness tradeoff in millimeter-wave MIMO systems," Signal Process., vol. 158, pp. 141-149, Jan. 2019.

Link to code: https://github.com/anzhonghu/User-scheduling-for-capacity-Jain-s-fairness-tradeoff-in-millimeter-wave-MIMO-systems

Maximizing minimum phase difference based hybrid beamforming for multiuser mmWave massive MIMO systems

Published in Proc. 2018 IEEE 4th Int. Conf. Comput. Commun. (ICCC), 2018

In this paper, we propose a hybrid beamforming algorithm based on maximizing the minimum phase difference for millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) multiuser systems.

Recommended citation: Y. Ding and A. Hu, "Maximizing minimum phase difference based hybrid beamforming for multiuser mmWave massive MIMO systems," in Proc. 2018 IEEE 4th Int. Conf. Comput. Commun. (ICCC), Chengdu, China, pp. 403-408, Dec. 2018.

Link to code: https://github.com/anzhonghu/Maximizing-minimum-phase-difference-based-hybrid-beamforming-for-multiuser-mmWave-massive-MIMO-syste

Beam grouping based user scheduling in multi-cell millimeter-wave MIMO systems

Published in IEEE Access, 2018

This paper investigates the user scheduling in multi-cell millimeter-wave multiple-input multiple-output systems, and a user scheduling criterion which minimizes the inter-cell interference and maximizes the effective channel gain is proposed.

Recommended citation: A. Hu, "Beam grouping based user scheduling in multi-cell millimeter-wave MIMO systems," IEEE Access, vol. 6, pp. 55004-55012, Oct. 2018.

Link to code: https://github.com/anzhonghu/Beam-grouping-based-user-scheduling-in-multi-cell-millimeter-wave-MIMO-systems

Concavity approximation based power allocation in millimeter-wave MIMO systems

Published in IEEE Access, 2017

This paper investigates the power allocation in millimeter-wave multiple-input multiple-output systems, in which the proposed approach utilizes a channel asymptotic orthogonality-based approximation which is more suitable, thus achieves higher spectral efficiency.

Recommended citation: A. Hu and P. Pan, "Concavity approximation based power allocation in millimeter-wave MIMO systems," IEEE Access, vol. 5, pp. 25731-25740, Dec. 2017.

Link to code: https://github.com/anzhonghu/Concavity-approximation-based-power-allocation-in-millimeter-wave-MIMO-systems

Antenna tilt adaptation for multi-cell massive MIMO systems

Published in IEEE Commun. Lett., 2017

This letter proposes an antenna tilt adaptation approach for multi-cell massive multiple-input multiple-output systems, and a gradient descent-based method is proposed to approach the optimal tilt.

Recommended citation: A. Hu, "Antenna tilt adaptation for multi-cell massive MIMO systems," IEEE Commun. Lett., vol. 21, no. 11, pp. 2436-2439, Nov. 2017.

Link to code: https://github.com/anzhonghu/Antenna-tilt-adaptation-for-multi-cell-massive-MIMO-systems

Channel estimation for interference mitigation in millimeter-wave multi-cell beamspace MIMO systems

Published in J. Commun. Networks, 2017

This paper deals with the inter-cell interference (ICI) mitigation in the channel estimation process of millimeter-wave multi-cell beamspace multiple-input multiple-output systems. The in-cell channels and the ICI channels are estimated together and distinguished with the beam information. In addition, the beamspace channels are estimated with small error by utilizing the asymptotic property of the beamspace channels.

Recommended citation: A. Hu, " Channel estimation for interference mitigation in millimeter-wave multi-cell beamspace MIMO systems," J. Commun. Networks, vol. 19, no. 4, pp. 371-382, Aug. 2017.

Link to code: https://github.com/anzhonghu/Channel-estimation-for-interference-mitigation-in-millimeter-wave-multi-cell-beamspace-MIMO-systems

Antenna tilt design for millimeter-wave beamspace MIMO systems

Published in Wireless Personal Commun., 2017

A joint design of the mechanical and the electrical tilts is proposed for millimeter-wave beamspace multiple-input multiple-output systems.

Recommended citation: A. Hu, " Antenna tilt design for millimeter-wave beamspace MIMO systems," Wireless Personal Commun., vol. 94, no. 3, pp. 1701-1713, Jun. 2017.

Link to code: https://github.com/anzhonghu/Antenna-tilt-design-for-millimeter-wave-beamspace-MIMO-systems

Single branch search based pilot allocation for multi-cell massive multiple-input multiple-output systems

Published in IET Commun., 2017

The performance of multi-cell massive multiple-input multiple-output systems is constrained by inter-cell interference. In this study, a pilot allocation approach is proposed to mitigate interference in such systems.

Recommended citation: A. Hu and H. Wang, "Single branch search based pilot allocation for multi-cell massive multiple-input multiple-output systems," IET Commun., vol. 11, no. 5, pp. 726-732, Mar. 2017.

Link to code: https://github.com/anzhonghu/Single-branch-search-based-pilot-allocation-for-multi-cell-massive-multiple-input-multiple-output-sy

DOA-based beamforming for multi-cell massive MIMO systems

Published in J. Commun. Networks, 2016

This paper proposes a direction-of-arrival (DOA)-based beamforming approach for multi-cell massive multiple-input multiple-output systems with uniform rectangular arrays (URAs). The proposed approach utilizes the steering vectors of the URA to form a basis of the spatial space and selects the partial space for beamforming according to the DOA information.

Recommended citation: A. Hu, "DOA-based beamforming for multi-cell massive MIMO systems," J. Commun. Networks, vol. 18, no. 5, pp. 735-743, Oct. 2016.

Estimation of sparse channels in millimeter-wave MU-MIMO systems

Published in KSII Trans. Internet and Inform. Syst., 2016

This paper considers a channel estimation scheme for millimeter-wave multiuser multiple-input multiple-output systems. According to the proposed method, parts of the beams are selected and the channel parameters are estimated according to the sparsity of channels and the orthogonality of the beams.

Recommended citation: A. Hu, "Estimation of sparse channels in millimeter-wave MU-MIMO systems," KSII Trans. Internet and Inform. Syst., vol. 10, no. 5, pp.2102-2122, May 2016.

Link to code: https://github.com/anzhonghu/Estimation-of-sparse-channels-in-millimeter-wave-MU-MIMO-systems

Statistical beamforming for interference mitigation in multi-cell massive MIMO systems

Published in Frequenz, 2016

This paper proposes a statistical beamforming approach to mitigate interference in multi-cell massive multiple-input multiple-output systems.

Recommended citation: A. Hu, "Statistical beamforming for interference mitigation in multi-cell massive MIMO systems," Frequenz, vol. 70, no. 1-2, pp. 47-56, Jan. 2016.

Link to code: https://github.com/anzhonghu/Statistical-beamforming-for-interference-mitigation-in-multi-cell-massive-MIMO-systems

An ESPRIT-based approach for 2-D localization of incoherently distributed sources in massive MIMO systems

Published in IEEE J. Select. Topics Signal Process., 2014

In this paper, an approach of estimating signal parameters via rotational invariance technique (ESPRIT) is proposed for two-dimensional (2-D) localization of incoherently distributed (ID) sources in large-scale/massive multiple-input multiple-output (MIMO) systems.

Recommended citation: A. Hu, T. Lv, H. Gao, et al, "An ESPRIT-based approach for 2-D localization of incoherently distributed sources in massive MIMO systems," IEEE J. Select. Topics Signal Process., vol. 8, no. 5, pp. 996-1011, Oct. 2014.

Link to code: https://github.com/anzhonghu/An-ESPRIT-based-approach-for-2-D-localization-of-incoherently-distributed-sources-in-massive-MIMO-sy

A distribution fitting approach for localization of multiple scattered sources with very large arrays

Published in Proc. 2013 IEEE Military Commun. Conf.(MILCOM), 2013

In this paper, a distribution fitting approach is proposed to estimate the angular parameters of multiple incoherently distributed sources with large antenna arrays.

Recommended citation: A. Hu and T. Lv, "A distribution fitting approach for localization of multiple scattered sources with very large arrays," in Proc. 2013 IEEE Military Commun. Conf.(MILCOM), San Diego, USA, pp. 453-457, Nov. 2013.

Link to code: https://github.com/anzhonghu/A-distribution-fitting-approach-for-localization-of-multiple-scattered-sources-with-very-large-array

Pilot design for large-scale multi-cell multiuser MIMO systems

Published in Proc. 2013 IEEE Int. Conf. Commun. (ICC), 2013

Large-scale multi-cell multiuser multiple-input multiple-output (LS-MIMO) systems can greatly increase the spectral efficiency. But the performance of these systems is deteriorated by pilot contamination. In this paper, first, a pilot design criterion is proposed by exploiting the orthogonality of channel vectors of LS-MIMO systems. Second, following this criterion, Chu sequences based pilots are designed. Because of the proposed pilots, the channel estimate of most terminals of a cell is only interfered by the partial cells rather than all the other cells, where the latter is caused by traditional pilots.

Recommended citation: A. Hu, T. Lv, H. Gao, et al, "Pilot design for large-scale multi-cell multiuser MIMO systems," in Proc. 2013 IEEE Int. Conf. Commun. (ICC), Budapest, Hungary, pp. 1-5, Jun. 2013.

Link to code: https://github.com/anzhonghu/Pilot-design-for-large-scale-multi-cell-multiuser-MIMO-systems

Subspace-based semi-blind channel estimation for large-scale multi-cell multiuser MIMO systems

Published in Proc. 2013 IEEE 77th Veh. Tech. Conf. (VTC Spring), 2013

Large-scale multi-cell multiuser multiple-input multiple-output (LS-MIMO) systems have received much attention recently. But the performance of these systems is deteriorated by imperfect channel state information (CSI). Hence, in this paper, a subspace-based semi-blind channel estimator is proposed.

Recommended citation: A. Hu, T. Lv, and Y. Lu, "Subspace-based semi-blind channel estimation for large-scale multi-cell multiuser MIMO systems," in Proc. 2013 IEEE 77th Veh. Tech. Conf. (VTC Spring), Dresden, Germany, pp. 1-5, Jun. 2013.

Link to code: https://github.com/anzhonghu/Subspace-based-semi-blind-channel-estimation-for-large-scale-multi-cell-multiuser-MIMO-systems

Other participated papers

Published in Conferences, 2013