Beamforming Design Based on Two-Stage Stochastic Optimization for RIS-Assisted Over-the-Air Computation Systems

Zhai, Xiongfei; Han, Guangjie; Hanzo, Lajos

doi:10.1109/jiot.2021.3108894

Cited by 20 publications

(15 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…RISs have also been exploited in AirComp systems [27]- [30]. In particular, a joint active and passive beamforming design based on difference-of-convex (DC) programming and matrix lifting has been proposed in [27] for minimizing the computation MSE.…”

Section: A Prior Workmentioning

confidence: 99%

Simultaneously Transmitting and Reflecting (STAR) RIS Assisted Over-the-Air Computation Systems

Zhai

Han

Liu

et al. 2023

IEEE Trans. Commun.

Self Cite

View full text Add to dashboard Cite

The performance of over-the-air computation (Air-Comp) systems degrades due to the hostile channel conditions of wireless devices (WDs), which can be significantly improved by the employment of reconfigurable intelligent surfaces (RISs). However, the conventional RISs require that the WDs have to be located in the half-plane of the reflection space, which restricts their potential benefits. To address this issue, the novel family of simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) is considered in AirComp systems to improve the computation accuracy across a wide coverage area. To minimize the computation mean-squared-error (MSE) in STAR-RIS assisted AirComp systems, we propose a joint beamforming design for optimizing both the transmit power at the WDs, as well as the passive reflect and transmit beamforming matrices at the STAR-RIS, and the receive beamforming vector at the fusion center (FC). Specifically, in the updates of the passive reflect and transmit beamforming matrices, closed-form solutions are derived by introducing an auxiliary variable and exploiting the coupled binary phase-shift conditions. Moreover, by assuming that the number of antennas at the FC and that of elements at the STAR-RIS/RIS are sufficiently high, we theoretically prove that the STAR-RIS assisted AirComp systems provide higher computation accuracy than the conventional RIS assisted systems. Our numerical results show that the proposed beamforming design outperforms the benchmark schemes relying on random phase-shift constraints and the deployment of conventional RIS. Moreover, its performance is close to the lower bound achieved

show abstract

Section: A Prior Workmentioning

confidence: 99%

Simultaneously Transmitting and Reflecting (STAR) RIS Assisted Over-the-Air Computation Systems

Zhai

Han

Liu

et al. 2023

IEEE Trans. Commun.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Intelligent reflecting surface (IRS), a metasurface equipped with massive reflecting elements [4], is a promising technology for enabling URLLC [1]. It is able to reconfigure the wireless environment and turn the random wireless channels into partially deterministic ones by beamforming design [5][6][7]. As a result, the received signal-to-noise ratio (SNR) can be significantly improved.…”

Section: A Related Workmentioning

confidence: 99%

Robust Beamforming Design for IRS-Aided URLLC in D2D Networks

Cheng

Shen

Chen

et al. 2022

IEEE Trans. Commun.

View full text Add to dashboard Cite

Intelligent reflecting surface (IRS) and device-todevice (D2D) communication are two promising technologies for improving transmission reliability between transceivers in communication systems. In this paper, we consider the design of reliable communication between the access point (AP) and actuators for a downlink multiuser multiple-input single-output (MISO) system in the industrial IoT (IIoT) scenario. We propose a two-stage protocol combining IRS with D2D communication so that all actuators can successfully receive the message from AP within a given delay. The superiority of the protocol is that the communication reliability between AP and actuators is doubly augmented by the IRS-aided first-stage transmission and the second-stage D2D transmission. A joint optimization problem of active and passive beamforming is formulated, which aims to maximize the number of actuators with successful decoding. We study the joint beamforming problem for cases where the channel state information (CSI) is perfect and imperfect. For each case, we develop efficient algorithms that include convergence and complexity analysis. Simulation results demonstrate the necessity and role of IRS with a well-optimized reflection matrix, and the D2D network in promoting reliable communication. Moreover, the proposed protocol can enable reliable communication even in the presence of stringent latency requirements and CSI estimation errors.Index Terms-D2D communication, industrial Internet of things (IIoT), intelligent reflecting surface (IRS), robust beamforming, URLLC I. INTRODUCTIONWith the development of the Internet of things (IoT) and the fifth-generation (5G) and beyond wireless networks, the Manuscript

show abstract

“…As we can see, problem P4 is a quadratic problem with constant modulus constraints. To address such passive beamforming optimization problem for RISs, SDR is generally considered as one of effective methods in the literature [35]- [38]. Besides, there are some other alternating methods, e.g., PDD and Manifold optimization.…”

Section: B Optimization Of the Receive Beamforming Vector Umentioning

confidence: 99%

“…ζ({v k,r }, θ 1,r+1 , θ 2,r , u r ) ≤ ζ({v k,r }, θ 1,r , θ 2,r , u r ), (38) ζ({v k,r }, θ 1,r , θ 2,r+1 , u r ) ≤ ζ({v k,r }, θ 1,r , θ 2,r , u r ). (39) By combining ( 36)-( 39), the objective function value of problem P1 is lower bounded by zero and non-increasing at each iteration.…”

Section: Appendix a Proof Of Theoremmentioning

confidence: 99%

“…Given the above advantages, RISs have received special attention in various areas, including RISassisted physical layer security [25]- [27], RIS-aided wireless power transfer [28]- [32], and RIS-assisted OFDM [33], [34], etc. Furthermore, RIS-assisted AirComp systems have also been studied in [35]- [38]. Specifically, to tackle the joint active and passive beamforming problem of RIS-assisted AirComp systems, the authors of [35] proposed a novel beamforming algorithm based on difference-of-convex (DC) programming and matrix lifting.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Joint Beamforming Aided Over-the-Air Computation Systems Relying on Both BS-Side and User-Side Reconfigurable Intelligent Surfaces

Zhai

Han

Hanzo

2022

IEEE Trans. Wireless Commun.

Self Cite

View full text Add to dashboard Cite

Over-the-air computation (AirComp) has received substantial attention, given its ability to aggregate massive amounts of data from distributed wireless devices (WDs). However, the computation accuracy at the fusion center (FC) may be severely affected by receiving data corrupted by the poor channel conditions. To mitigate this issue, we consider the employment of reconfigurable intelligent surfaces (RISs) in the AirComp system considered for improving the quality of received data, and hence improve the computation accuracy. However, most previous contributions on RIS-assisted AirComp systems only employ a single RIS in the resultant single-RIS-assisted (SRISassisted) AirComp systems. We develop this concept further for mitigating the deleterious channel effects by conceiving a double-RIS-assisted (DRIS-assisted) AirComp system, where one of the RISs is located near the WDs and the other in the vicinity of the FC. We theoretically prove that the DRIS-assisted AirComp system outperforms its SRIS-assisted counterpart in terms of the resultant computation mean-squared-error (MSE). Furthermore, we propose a pair of algorithms for jointly optimizing the transmit power at the WDs, the receive beamforming vector at the FC, and the passive beamforming matrices at the RISs for minimizing the computational MSE. Specifically, the transmit power is updated by exploiting the Lagrange duality method, while the receive beamforming vector is optimized by utilizing the first-order optimality condition. Furthermore, a pair of techniques are developed for optimizing the passive beamforming matrices at the RISs based on semidefinite relaxation (SDR) and penalty-duality-decomposition (PDD), respectively. Both the complexity and the convergence of the proposed algorithms are analyzed. Finally, simulation results are provided for quantifying the overall performance of the resultant DRIS-assisted AirComp system.Index Terms-Over-the-air computation (AirComp), Internetof-Things (IoT) networks, double reconfigurable intelligent surfaces (DRIS).

show abstract

Beamforming Design Based on Two-Stage Stochastic Optimization for RIS-Assisted Over-the-Air Computation Systems

Cited by 20 publications

References 55 publications

Simultaneously Transmitting and Reflecting (STAR) RIS Assisted Over-the-Air Computation Systems

Simultaneously Transmitting and Reflecting (STAR) RIS Assisted Over-the-Air Computation Systems

Robust Beamforming Design for IRS-Aided URLLC in D2D Networks

Joint Beamforming Aided Over-the-Air Computation Systems Relying on Both BS-Side and User-Side Reconfigurable Intelligent Surfaces

Contact Info

Product

Resources

About