Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul
In this paper, we consider the robust beamforming design in a reconfigurable intelligent surface (RIS)-aided cell-free (CF) system considering the channel state information (CSI) uncertainties of both the direct channels and cascaded channels at the transmitter with capacity-limited backhaul. We joi...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
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2023
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| Online Access: | https://hdl.handle.net/10356/172080 |
| _version_ | 1811679585570390016 |
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| author | Yao, Jiacheng Xu, Jindan Xu, Wei Ng, Derrick Wing Kwan Yuen, Chau You, Xiaohu |
| author2 | School of Electrical and Electronic Engineering |
| author_facet | School of Electrical and Electronic Engineering Yao, Jiacheng Xu, Jindan Xu, Wei Ng, Derrick Wing Kwan Yuen, Chau You, Xiaohu |
| author_sort | Yao, Jiacheng |
| collection | NTU |
| description | In this paper, we consider the robust beamforming design in a reconfigurable intelligent surface (RIS)-aided cell-free (CF) system considering the channel state information (CSI) uncertainties of both the direct channels and cascaded channels at the transmitter with capacity-limited backhaul. We jointly optimize the precoding at the access points (APs) and the phase shifts at multiple RISs to maximize the worst-case sum rate of the CF system subject to the constraints of maximum transmit power of APs, unit-modulus phase shifts, limited backhaul capacity, and bounded CSI errors. By applying a series of transformations, the non-smoothness and semi-infinite constraints are tackled in a low-complexity manner that facilitates the design of an alternating optimization (AO)-based iterative algorithm. The proposed algorithm divides the considered problem into two subproblems. For the RIS phase shifts optimization subproblem, we exploit the penalty convex-concave procedure (P-CCP) to obtain a stationary solution and achieve effective initialization. For precoding optimization subproblem, successive convex approximation (SCA) is adopted with a convergence guarantee to a Karush-Kuhn-Tucker (KKT) solution. Numerical results demonstrate the effectiveness of the proposed robust beamforming design, which achieves superior performance with low complexity. Moreover, the importance of RIS phase shift optimization for robustness and the advantages of distributed RISs in the CF system are further highlighted. |
| first_indexed | 2024-10-01T03:11:30Z |
| format | Journal Article |
| id | ntu-10356/172080 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T03:11:30Z |
| publishDate | 2023 |
| record_format | dspace |
| spelling | ntu-10356/1720802023-11-22T01:16:28Z Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul Yao, Jiacheng Xu, Jindan Xu, Wei Ng, Derrick Wing Kwan Yuen, Chau You, Xiaohu School of Electrical and Electronic Engineering Engineering::Electrical and electronic engineering Robust Beamforming Design Capacity-Limited Backhaul In this paper, we consider the robust beamforming design in a reconfigurable intelligent surface (RIS)-aided cell-free (CF) system considering the channel state information (CSI) uncertainties of both the direct channels and cascaded channels at the transmitter with capacity-limited backhaul. We jointly optimize the precoding at the access points (APs) and the phase shifts at multiple RISs to maximize the worst-case sum rate of the CF system subject to the constraints of maximum transmit power of APs, unit-modulus phase shifts, limited backhaul capacity, and bounded CSI errors. By applying a series of transformations, the non-smoothness and semi-infinite constraints are tackled in a low-complexity manner that facilitates the design of an alternating optimization (AO)-based iterative algorithm. The proposed algorithm divides the considered problem into two subproblems. For the RIS phase shifts optimization subproblem, we exploit the penalty convex-concave procedure (P-CCP) to obtain a stationary solution and achieve effective initialization. For precoding optimization subproblem, successive convex approximation (SCA) is adopted with a convergence guarantee to a Karush-Kuhn-Tucker (KKT) solution. Numerical results demonstrate the effectiveness of the proposed robust beamforming design, which achieves superior performance with low complexity. Moreover, the importance of RIS phase shift optimization for robustness and the advantages of distributed RISs in the CF system are further highlighted. Ministry of Education (MOE) This work was supported in part by the National Key Research and Development Program 2020YFB1806608; in part by the NSFC under Grants 62022026 and 62211530108; in part by the Fundamental Research Funds for the Central Universities under Grants 2242022K60002 and 2242023K5003. The work of D. W. K. Ng was supported by the Australian Research Council’s Discovery Project (DP210102169, DP230100603). This work of C. Yuen was supported by the Ministry of Education, Singapore, under its MOE Tier 2 (Award number MOE-T2EP50220-0019). 2023-11-22T01:16:28Z 2023-11-22T01:16:28Z 2023 Journal Article Yao, J., Xu, J., Xu, W., Ng, D. W. K., Yuen, C. & You, X. (2023). Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul. IEEE Transactions On Communications, 71(8), 4636-4649. https://dx.doi.org/10.1109/TCOMM.2023.3277539 0090-6778 https://hdl.handle.net/10356/172080 10.1109/TCOMM.2023.3277539 2-s2.0-85160226254 8 71 4636 4649 en MOE-T2EP50220-0019 IEEE Transactions on Communications © 2023 IEEE. All rights reserved. |
| spellingShingle | Engineering::Electrical and electronic engineering Robust Beamforming Design Capacity-Limited Backhaul Yao, Jiacheng Xu, Jindan Xu, Wei Ng, Derrick Wing Kwan Yuen, Chau You, Xiaohu Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul |
| title | Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul |
| title_full | Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul |
| title_fullStr | Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul |
| title_full_unstemmed | Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul |
| title_short | Robust beamforming design for RIS-aided cell-free systems with CSI uncertainties and capacity-limited backhaul |
| title_sort | robust beamforming design for ris aided cell free systems with csi uncertainties and capacity limited backhaul |
| topic | Engineering::Electrical and electronic engineering Robust Beamforming Design Capacity-Limited Backhaul |
| url | https://hdl.handle.net/10356/172080 |
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