I am a Postdoctoral Researcher with KTH Royal Institute of Technology, Sweden, since Sep/2025. My supervisor is Prof. Emil Björnson. I received my Ph.D. degree with with the School of Electronic and Information Engineering, Beijing Jiaotong University, China, since Sep/2020. My Ph.D. supervisor is Prof. Jiayi Zhang. From Nov/2023 to Nov/2024, I was a visiting Ph.D. student at the School of Computer Science and Engineering, Nanyang Technological University, Singapore. My supervisor during my visiting time at Nanyang Technological University is Prof. Dusit Niyato.

My research primarily focuses on next-generation MIMO technology, including extremely large-scale MIMO (XL-MIMO) and cell-free massive MIMO (CF mMIMO). Our key objective is to explore "performance analysis and efficient design for next-generation MIMO systems". You can find my simulation source codes in my GitHub account. If you are interested in our work, you can refer to this repository for the latest updates of Prof. Emil Björnson’s research group, and this repository and WeChat official account (ID: BJTU MIMO) for the latest updates of Prof. Jiayi Zhang group!

If you have any questions or have an interest in collaborating with me, please feel free to email me (zhewang2@kth.se)!

News

1. [Nov. 2025] One first-author paper titled “Flexible MIMO for Future Wireless Communications: Which Flexibilities are Possible?” has been accepted by IEEE Wireless Communications.
2. [Sep. 2025] I have started my new journey as a Postdoctoral Researcher with KTH Royal Institute of Technology, Sweden.
3. [Sep. 2025] One collaborative paper titled “Asynchronous Distributed Beamforming for Beyond-Diagonal RIS-aided Movable Antenna Systems” has been accepted by IEEE Transactions on Wireless Communications.
4. [Jul. 2025] One first-author paper titled “A Tutorial on Extremely Large-Scale MIMO for 6G: Fundamentals, Signal Processing, and Applications” has been an ESI Hot Paper.
5. [Jun. 2025] I have successfully defended my Ph.D. theis. Many thanks to my supervisor Prof. Jiayi Zhang and all defense committee members.
6. [May 2025] One collaborative paper titled “Performance Analysis of XL-MIMO With Rotary and Movable Antennas for High-Speed Railway” has been accepted by IEEE Transactions on Vehicular Technology.
7. [Apr. 2025] One collaborative paper titled “Mobility-Aware Near-Field Beam Training in XL-MIMO Systems for High-Speed Railway” has been accepted by IEEE Wireless Communications Letters.
8. [Mar. 2025] One collaborative paper titled “ROMA: Rotary and Movable Antenna” has been accepted by IEEE Wireless Communications Letters.
9. [Mar. 2025] One first-author paper titled “Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over Correlated Rician Channels” has been accepted by IEEE Transactions on Signal Processing.

Submitted Papers

1. Zhe Wang, Jiayi Zhang, Bokai Xu, Dusit Niyato, Bo Ai, Shiwen Mao, and Zhu Han, “Low-Complexity Distributed Combining Design for Near-Field Cell-Free XL-MIMO Systems” submitted to IEEE Transactions on Wireless Communications, 2025.

First-Author Papers

For all publications, please refer to Publications or my google scholar.

1. Zhe Wang, Jiayi Zhang, Bokai Xu, Wenhui Yi, Emil Björnson, and Bo Ai, “Flexible MIMO for Future Wireless Communications: Which Flexibilities are Possible?” IEEE Wireless Communications, accepted, 2025. We present a taxonomy framework, referred to as flexible MIMO, that systematically categorizes a wide range of evolving MIMO technologies.
2. Zhe Wang, Jiayi Zhang, Hongyang Du, Ruichen Zhang, Dusit Niyato, Bo Ai, and Khaled B. Letaief, “Large Language Model Empowered Next-Generation MIMO Networks: Fundamentals, Challenges, and Visions,” Digital Communications and Networks, accepted, 2025. We study the large language model enabled next-generation MIMO networks.
3. Zhe Wang, Jiayi Zhang, Emil Björnson, Dusit Niyato, and Bo Ai, “Optimal Bilinear Equalizer for Cell-Free Massive MIMO Systems over Correlated Rician Channels,” IEEE Transactions on Signal Processing, accepted, 2025. We explore the low-complexity optimal bilinear equalizer (OBE) combining scheme design for cell-free massive multiple-input multiple-output networks with spatially correlated Rician fading channels.[Download Simulation Code]
4. Zhe Wang, Jiayi Zhang, Wenhui Yi, Huahua Xiao, Hongyang Du, Dusit Niyato, Bo Ai, “Analytical Framework for Effective Degrees of Freedom in Near-Field XL-MIMO,” IEEE Transactions on Wireless Communications, accepted, 2025. We develop an effective degrees of freedom (EDoF) performance analysis framework specifically tailored for near-field XL-MIMO systems with various hardware designs.[Download Simulation Code]
5. Zhe Wang, Jiayi Zhang, Hao Lei, Dusit Niyato, and Bo Ai, “Optimal Bilinear Equalizer Beamforming Design for Cell-Free Massive MIMO Networks with Arbitrary Channel Estimators,” IEEE Transactions on Vehicular Technology, accepted, 2024. This paper studies the distributed optimal bilinear equalizer (OBE) beamforming design for both the uplink and downlink cell-free massive multiple-input multiple-output networks. We consider arbitrary statistics-based channel estimators over spatially correlated Rician fading channels.[Download Simulation Code]
6. Zhe Wang, Jiayi Zhang, Wenhui Yi, Huahua Xiao, Dusit Niyato, and Bo Ai, “Effective Degree of Freedom for Near-Field Plane-Based XL-MIMO with Tri-Polarization,” Frontiers of Information Technology & Electronic Engineering, vol. 25, no. 12, pp. 1723-1731, Dec. 2024. We provide EDoF performance analysis framework for plane-based XL-MIMO systems with triple polarization.
7. Zhe Wang, Jiayi Zhang, Hongyang Du, Dusit Niyato, Shuguang Cui, Bo Ai, Mérouane Debbah, Khaled B. Letaief, and H. Vincent Poor, “A Tutorial on Extremely Large-Scale MIMO for 6G: Fundamentals, Signal Processing, and Applications,” IEEE Communications Surveys & Tutorials, vol. 26, no. 3, pp. 1560-1605, third quarter, 2024. We provide a comprehensive survey for XL-MIMO technology, including hardware design, channel modeling, signal processing, application scenarios, and future research directions.
8. Zhe Wang, Jiayi Zhang, Hongyang Du, Wei E. I. Sha, Bo Ai, Dusit Niyato, and Mérouane Debbah, “Extremely Large-Scale MIMO: Fundamentals, Challenges, Solutions, and Future Directions,” IEEE Wireless Communications, vol. 31, no. 3, pp. 117-124, Jun. 2024. We briefly overview the basic fundamentals of XL-MIMO and explore the EDoF performance for non-parallel transceiver and multi-user scenarios.
9. Zhe Wang, Jiayi Zhang, Hien Quoc Ngo, Bo Ai, and Mérouane Debbah, “Uplink Precoding Design for Cell-Free Massive MIMO with Iteratively Weighted MMSE,” IEEE Transactions on Communications, vol. 70, no. 3, pp. 1646-1664, Mar. 2023. To efficiently benefit from multiple antennas at the user-side, we study the uplink precoding design in CF mMIMO systems based on Iteratively Weighted sum-Minimum Mean Square Error (I-WMMSE) algorithms. [Download Simulation Code]
10. Zhe Wang, Jiayi Zhang, Bo Ai, Chau Yuen, and Mérouane Debbah, “Uplink Performance of Cell-Free Massive MIMO with Multi-Antenna Users Over Jointly-Correlated Rayleigh Fading Channels,” IEEE Transactions on Wireless Communications, vol. 21, no. 9, pp. 7391–7406, Sep. 2022. We study four uplink implementations for CF mMIMO systems with multi-antenna users, from fully centralized processing to fully distributed processing. We observe that the system performance may not always benefit from the number of antennas per user.[Download Simulation Code]
11. Zhe Wang, Jiayi Zhang, Hien Quoc Ngo, Bo Ai, and Mérouane Debbah, “Iteratively Weighted MMSE Uplink Precoding for Cell-Free Massive MIMO,” IEEE International Conference on Communications (ICC), 2022. A conference version of "Uplink Precoding Design for Cell-Free Massive MIMO with Iteratively Weighted MMSE,"
12. Zhe Wang, Jiayi Zhang, Emil Björnson, and Bo Ai, “Uplink Performance of Cell-Free Massive MIMO Over Spatially Correlated Rician Fading Channels,” IEEE Communications Letters, vol. 25, no. 4, pp. 1348–1352, Apr. 2021. We analyze the uplink spectral efficiency for CF mMIMO systems over spatially correlated Rician fading channels. This channel is practical due to the consideration of phase-shift and spatial correlation.[Download Simulation Code]

Collaborative Papers

For all publications, please refer to Publications or my google scholar.

1. Qiang Sun, Xiaodi Ji, Zhe Wang, Xiaomin Chen, Yongjie Yang, Jiayi Zhang, and Kai-Kit Wong, “Uplink Performance of Hardware-Impaired Cell-Free Massive MIMO with Multi-Antenna Users and Superimposed Pilots,” IEEE Transactions on Communications, vol. 71, no. 11, pp. 6711–6726, Nov. 2023. We study uplink performance of hardware-impaired CF mMIMO systems with multi-antenna users and superimposed pilots, where all the coherence intervals are used for both pilot and data symbols transmission.
2. Bokai Xu, Zhe Wang, Huahua Xiao, Jiayi Zhang, Bo Ai, and Derrick Wing Kwan Ng, “Low-Complexity Precoding for Extremely Large-Scale MIMO Over Non-Stationary Channels,” International Conference on Communications (ICC), 2023. We investigate a low-complexity precoding algorithm, e.g., randomized Kaczmarz (rKA), taking into account the spatial non-stationary properties in XL-MIMO systems. [Download Simulation Code]
3. Xin Li, Jiayi Zhang, Zhe Wang, Bo Ai, and Derrick Wing Kwan Ng, “Cell-Free Massive MIMO with Multi-Antenna Users over Weichselberger Rician Channels,” IEEE Transactions on Vehicular Technology, vol. 71, no. 11, pp. 12368–12373, Nov. 2022. We study CF mMIMO systems with multi-antenna users over Weichselberger Rician fading channels with random phase-shifts. We propose a practical uplink precoding scheme based on only the eigenbasis of the user-side correlation matrices. [Download Simulation Code]
4. Zhilong Liu, Jiayi Zhang, Zhe Wang, Bo Ai, and Derrick Wing Kwan Ng, “Cell-Free Massive MIMO with Low-Resolution ADCs and I/Q Imbalance Over Spatially Correlated Channels,” IEEE Global Communications Conference (Globecom), 2022. We investigate CF mMIMO systems with low-resolution analog-to-digital converters (ADCs) and in-phase and quadrature-phase imbalance (IQI) over multi-antenna users. The achievable uplink spectral efficiency is analyzed based on a two-layer decoding scheme.
5. Hao Lei, Jiayi Zhang, Zhe Wang, Bo Ai, and Derrick Wing Kwan Ng, “Hybrid-Field Channel Estimation for XL-MIMO Systems with Stochastic Gradient Pursuit Algorithm,” IEEE Transactions on Signal Processing, accepted, 2024. We introduce two stochastic gradient pursuit (SGP)-based schemes for the XL-MIMO hybrid-field channel estimation in two scenarios. [Download Simulation Code]
6. Bokai Xu, Jiayi Zhang, Hongyang Du, Zhe Wang, Yuanwei Liu, Dusit Niyato, Bo Ai, and Khaled B. Letaief, “Resource Allocation for Near-Field Communications: Fundamentals, Tools, and Outlooks,” IEEE Wireless Communications, accepted, 2024. We review the basic properties of near-field communications and focus on the corresponding "resource allocation" problems.
7. Haiquan Lu, Yong Zeng, Changsheng You, Yu Han, Jiayi Zhang, Zhe Wang, Zhenjun Dong, Shi Jin, Cheng-Xiang Wang, Tao Jiang, Xiaohu You, and Rui Zhang, “A Tutorial on Near-Field XL-MIMO Communications Towards 6G,” IEEE Communications Surveys & Tutorials, accepted, 2024. We give a comprehensive tutorial overview on near-field XL-MIMO communications, aiming to provide useful guidance for tackling the above challenges.
8. Zhilong Liu, Jiayi Zhang, Ziheng Liu, Hongyang Du, Zhe Wang, Dusit Niyato, Mohsen Guizani, and Bo Ai, “Cell-Free XL-MIMO Meets Multi-Agent Reinforcement Learning: Architectures, Challenges, and Future Directions,” IEEE Wireless Communications, accepted, 2023. We propose the enhanced paradigm of cell-free XL-MIMO, which incorporates multi-agent reinforcement learning (MARL) to provide a distributed strategy for tackling the problem of high-dimension signal processing and costly energy consumption.
9. Zhilong Liu, Jiayi Zhang, Zhe Wang, Xiaodan Zhang, Huahua Xiao, and Bo Ai, “Cell-Free Massive MIMO With Mixed-Resolution ADCs and I/Q Imbalance Over Rician Spatially Correlated Channels” IEEE Transactions on Vehicular Technology, vol. 72, no. 7, pp. 9567–9572, Jul. 2023. We investigate the effect of mixed-resolution ADCs deploying at access points and the in-phase and quadrature-phase imbalance (IQI) on the CF mMIMO systems over Rician spatially correlated channels.
10. Qiuhao Liu, Yonghao Lin, Jiakang Zheng, Zhe Wang, Jiayi Zhang, and Bo Ai, “Performance Analysis of XL-MIMO-OFDM Systems for High-Speed Train Communications” IEEE International Conference on Communications (ICC) Workshops, 2023. We analyze the performance of XL-MIMO-OFDM systems for high-speed train communication using extremely large aperture arrays (ELAAs) in line-of-sight (LoS) scenarios and investigate the factors that affect spectral efficiency.
11. Enyu Shi, Jiayi Zhang, Zhe Wang, Derrick Wing Kwan Ng, and Bo Ai, “Uplink Performance of RIS-aided Cell-Free Massive MIMO System Over Spatially Correlated Channels,” IEEE Global Communications Conference (Globecom), 2022. We consider a practical spatially correlated reconfigurable intelligent surface (RIS)-aided CF mMIMO system with multi-antenna access points over spatially correlated Rician fading channels.

Awards

1. National Scholarship, Ministry of Education of China, 2023
2. IEEE ICC 2023 Best Paper Awards, IEEE ComSoc, 2023
3. Third Prize in the 19th China Post-Graduate Mathematical Contest in Modeling , Association of Chinese Graduate Education, 2023
4. First Prize in the 17th China Graduate Electronics Design Contest , Association of Chinese Graduate Education, 2022
5. SiNuo Education Fund Scholarship, Beijing Jiaotong University, 2022
6. National Scholarship, Ministry of Education of China, 2020

Academic Services

1. TPC member, IEEE GLOBECOM 2024
2. TPC Member, IEEE PIMRC 2024, Track 2 - Networking & MAC
3. TPC Member, IEEE VTC 2023-Fall: Hong Kong, Electric Vehicles, Vehicular Electronics and Intelligent Transportation
4. Reviewer: IEEE JSAC, COMST, TCOM, TWC, IOTJ, TCCN, TIFS, TVT, TSM, WCL, and more.

“Stay gold, pony boy!”

———《The Secret Life of Walter Mitty》