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Open Access

Joint Beamforming Design for RIS-Assisted Cell-Free Network with Multi-Hop Transmissions

Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Beijing National Research Center for Information Science and Technology (BNRist), Beijing 100084, China
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Abstract

The collaboration of multiple Reconfigurable Intelligent Surfaces (RISs) and Access Points (APs) enjoys advantages of capacity enhancement, power saving, etc., making the RIS-assisted cell-free network an important architecture for future communications. Similar to most existing works on RIS-assisted communications, the multi-hop link among RISs, i.e., the reflecting link including more than one RISs, is usually ignored in RIS-assisted cell-free networks. In these scenarios, however, since multiple RISs are closely deployed, we find that the multi-hop channels should not be simply ignored due to their potential for capacity improvement. Unfortunately, to the best of our knowledge, there is no work exploring the multi-hop transmission of RIS-assisted cell-free networks. To fill in this blank, we investigate the multi-hop transmission of RIS-assisted cell-free networks, including the multi-hop channel model and the corresponding beamforming design. Specifically, we propose a general multi-hop transmission model, which takes the direct links, single-reflecting links, and multi-hop links into account. Based on this model, we formulate a beamforming design problem in an RIS-assisted cell-free network, which allows us to maximize the multi-user sum-rate with considering the impact of multi-hop channels. To address the non-convexity of the formulated problem, a joint active and passive beamforming scheme is proposed to solve the problem. Particularly, by utilizing fractional programming, we decouple the coupled beamforming parameters in the problem, and then these parameters are alternately optimized until the convergence of the sum-rate. Simulation results verify that the consideration for multi-hop links is necessary, and the capacity performance of the proposed scheme is 20% higher than those of the existing schemes.

References

[1]
C. Feng, W. Shen, J. An, and L. Hanzo, Joint hybrid and passive RIS-assisted beamforming for mmWave MIMO systems relying on dynamically configured subarrays, IEEE Internet Things J., vol. 9, no. 15, pp. 13913–13926, 2022.
[2]
H. Sun, S. Zhang, J. Ma, and O. A. Dobre, Time-delay unit based beam squint mitigation for RIS-aided communications, IEEE Commun. Lett., vol. 26, no. 9, pp. 2220–2224, 2022.
[3]
M. Wu, Z. Gao, Y. Huang, Z. Xiao, D. W. K. Ng, and Z. Zhang, Deep learning-based rate-splitting multiple access for reconfigurable intelligent surface-aided tera-hertz massive MIMO, IEEE J. Sel. Areas Commun., vol. 41, no. 5, pp. 1431–1451, 2023.
[4]
M. Jian and Y. Zhao, A modified off-grid SBL channel estimation and transmission strategy for RIS-assisted wireless communication systems, in Proc. 2020 Int. Wireless Communications and Mobile Computing (IWCMC’20), Limassol, Cyprus, 2020, pp. 1848–1853.
[5]
H. Liu, Y. Zhang, S. Gong, W. Shen, C. Xing, and J. An, Optimal transmission strategy and time allocation for RIS-enhanced partially WPSNs, IEEE Trans. Wireless Commun., vol. 21, no. 9, pp. 7207–7221, 2022.
[6]
J. Zhang, Z. Zheng, Z. Fei, and Z. Han, Energy-efficient multiuser localization in the RIS-assisted IoT networks, IEEE Internet Things J., vol. 9, no. 20, pp. 20651–20665, 2022.
[7]
X. Pang, N. Zhao, J. Tang, C. Wu, D. Niyato, and K. K. Wong, IRS-Assisted secure UAV transmission via joint trajectory and beamforming design, IEEE Trans. Commun., vol. 70, no. 2, pp. 1140–1152, 2022.
[8]
S. Liu, Z. Gao, J. Zhang, M. D. Renzo, and M. S. Alouini, Deep denoising neural network assisted compressive channel estimation for mmWave intelligent reflecting surfaces, IEEE Trans. Veh. Technol., vol. 69, no. 8, pp. 9223–9228, 2020.
[9]
M. Jian, R. Liu, E. Basar, Y. Liu, and C. Huang, Reconfigurable intelligent surface aided non-coaxial OAM transmission for capacity improvement, in Proc. 2022 IEEE/CIC Int. Conf. Communications in China (ICCC’22), Foshan, China, 2022, pp. 594–599.
[10]
E. Nayebi, A. Ashikhmin, T. L. Marzetta, and H. Yang, Cell-free massive MIMO systems, in Proc. 49th Asilomar Conf. Signals, Systems and Computers, Pacific Grove, CA, USA, 2015, pp. 695–699.
[11]
Z. Zhang and L. Dai, A joint precoding framework for wideband reconfigurable intelligent surface-aided cell-free network, IEEE Trans. Signal Process., vol. 69, pp. 4085–4101, 2021.
[12]
X. Gan, C. Zhong, C. Huang, Z. Yang, and Z. Zhang, Multiple RISs assisted cell-free networks with two-timescale CSI: Performance analysis and system design, IEEE Trans. Commun., vol. 70, no. 11, pp. 7696–7710, 2022.
[13]
E. Shi, J. Zhang, Z. Wang, D. W. K. Ng, and B. Ai, Uplink performance of RIS-aided cell-free massive MIMO system over spatially correlated channels, in Proc. GLOBECOM 2022 – 2022 IEEE Global Communications Conf., Rio de Janeiro, Brazil, 2022, pp. 3259–3264.
[14]
H. Ge, N. Garg, and T. Ratnarajah, Generalized superimposed channel estimation for uplink RIS-aided cell-free massive MIMO systems, in Proc. 2022 IEEE Wireless Communications and Networking Conf. (WCNC), Austin, TX, USA, 2022, pp. 405–410.
[15]
W. Li, W. Ni, R. Luo, H. Tian, Z. Yang, and C. Huang, Distributed RIS-enhanced cell-free NOMA networks, in Proc. 2022 IEEE Globecom Workshops (GC Wkshps), Rio de Janeiro, Brazil, 2022, pp. 106–111.
[16]
E. Shi, J. Zhang, S. Chen, J. Zheng, Y. Zhang, D. W. K. Ng, and B. Ai, Wireless energy transfer in RIS-aided cell-free massive MIMO systems: Opportunities and challenges, IEEE Commun. Mag., vol. 60, no. 3, pp. 26–32, 2022.
[17]
C. Huang, Z. Yang, G. C. Alexandropoulos, K. Xiong, L. Wei, C. Yuen, Z. Zhang, and M. Debbah, Multi-hop RIS-empowered terahertz communications: A DRL-based hybrid beamforming design, IEEE J. Sel. Areas Commun., vol. 39, no. 6, pp. 1663–1677, 2021.
[18]
Z. Zhang and Z. Zhao, Weighted sum-rate maximization for multi-hop RIS-aided multi-user communications: A minorization-maximization approach, in Proc. 2021 IEEE 22nd Int. Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Lucca, Italy, 2021, pp. 106–110.
[19]
K. Ardah, S. Gherekhloo, A. L. F. de Almeida, and M. Haardt, Double-RIS versus single-RIS aided systems: Tensor-based MIMO channel estimation and design perspectives, arXiv preprint arXiv: 2109.09099, 2021.
[20]
Y. Zhang and C. You, Multi-hop beam routing for hybrid active/passive IRS aided wireless communications, in Proc. GLOBECOM 2022 – 2022 IEEE Global Communications Conf., Rio de Janeiro, Brazil, 2022, pp. 3138–3143.
[21]
Z. Zhang, L. Dai, X. Chen, C. Liu, F. Yang, R. Schober, and H. V. Poor, Active RIS vs. passive RIS: Which will prevail in 6G? IEEE Trans. Commun., vol. 71, no. 3, pp. 1707–1725, 2023.
[22]
Q. Wu and R. Zhang, Intelligent reflecting surface enhanced wireless network via joint active and passive beamforming, IEEE Trans. Wireless Commun., vol. 18, no. 11, pp. 5394–5409, 2019.
[23]
M. Xu, S. Zhang, J. Ma, and O. A. Dobre, Deep learning-based time-varying channel estimation for RIS assisted communication, IEEE Commun. Lett., vol. 26, no. 1, pp. 94–98, 2022.
[24]
M. Z. Siddiqi and T. Mir, Reconfigurable intelligent surface-aided wireless communications: An overview, Intelligent and Converged Networks, vol. 3, no. 1, pp. 33–63, 2022.
[25]
K. Shen and W. Yu, Fractional programming for communication systems—Part I: Power control and beamforming, IEEE Trans. Signal Process., vol. 66, no. 10, pp. 2616–2630, 2018.
[26]
S. Boyd, N. Parikh, E. Chu, B. Peleato, and J. Eckstein, Distributed optimization and statistical learning via the alternating direction method of multipliers, https://stanford.edu/~boyd/papers/pdf/admm_distr_stats.pdf, 2014.
[27]
D. Shen and L. Dai, Multi-beam design for extremely large-scale RIS aided near-field wireless communications, in Proc. GLOBECOM 2022 – 2022 IEEE Global Communications Conf., Rio de Janeiro, Brazil, 2022, pp. 1–6.
[28]
G. Interdonato, E. Björnson, H. Q. Ngo, P. Frenger, and E. G. Larsson, Ubiquitous cell-free massive MIMO communications, EURASIP J. Wireless Commun. Netw., vol. 2019, p. 197, 2019.
Tsinghua Science and Technology
Pages 1115-1127
Cite this article:
Shen D, Zhang Z, Dai L. Joint Beamforming Design for RIS-Assisted Cell-Free Network with Multi-Hop Transmissions. Tsinghua Science and Technology, 2023, 28(6): 1115-1127. https://doi.org/10.26599/TST.2023.9010019

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Received: 28 February 2023
Revised: 17 March 2023
Accepted: 18 March 2023
Published: 28 July 2023
© The author(s) 2023.

The articles published in this open access journal are distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/).

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