Cascaded Channel Estimation for Large Intelligent Metasurface Assisted Massive MIMO

He, Zhen-Qing; Yuan, Xiaojun

doi:10.1109/lwc.2019.2948632

Cited by 724 publications

(487 citation statements)

References 21 publications

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“…Then, in [38], this method is modified by grouping the adjacent elements to reduce the training overhead. • Compressive-Sensing Method: In [39], a compressivesensing based method is proposed by exploiting the lowrank property of the RIS-aided link to further reduce the training overhead. • Semi-passive RIS: In [40], a semi-passive structure is suggested by integrating active elements on the RIS which have the channel estimation capability.…”

Section: B Discussion On Channel Estimationmentioning

confidence: 99%

“…In particular, the path-loss is set according to the 3GPP propagation environment [52, We assume the direct link channel h d,k follows Rayleigh fading, while the RIS-aided channels follow Rician fading. Same as [25] and [39], we further assume that the antenna elements form a half-wavelength uniform linear array configuration at the AP and the RIS, and thus the channels G and h r,k are modeled by…”

Section: A Simulation Scenariomentioning

confidence: 99%

See 1 more Smart Citation

Weighted Sum-Rate Maximization for Reconfigurable Intelligent Surface Aided Wireless Networks

Guo

Liang

Chen

et al. 2020

IEEE Trans. Wireless Commun.

776

521

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Reconfigurable intelligent surfaces (RIS) is a promising solution to build a programmable wireless environment via steering the incident signal in fully customizable ways with reconfigurable passive elements. In this paper, we consider a RISaided multiuser multiple-input single-output (MISO) downlink communication system. Our objective is to maximize the weighted sum-rate (WSR) of all users by joint designing the beamforming at the access point (AP) and the phase vector of the RIS elements, while both the perfect channel state information (CSI) setup and the imperfect CSI setup are investigated. For perfect CSI setup, a low-complexity algorithm is proposed to obtain the stationary solution for the joint design problem by utilizing the fractional programming technique. Then, we resort to the stochastic successive convex approximation technique and extend the proposed algorithm to the scenario wherein the CSI is imperfect. The validity of the proposed methods is confirmed by numerical results. In particular, the proposed algorithm performs quite well when the channel uncertainty is smaller than 10%.Index Terms-Reconfigurable intelligent surfaces (RIS), passive radio, multiple-input-multiple-output (MIMO), fractional programming, stochastic successive convex approximation.

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Section: B Discussion On Channel Estimationmentioning

confidence: 99%

Section: A Simulation Scenariomentioning

confidence: 99%

Weighted Sum-Rate Maximization for Reconfigurable Intelligent Surface Aided Wireless Networks

Guo

Liang

Chen

et al. 2020

IEEE Trans. Wireless Commun.

776

521

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show abstract

“…where |h RG,i | and ω i ∈ [0, 2π) are the magnitude and phase angle of the ith element of the complex vector h RG , respectively. In this letter, we assume that the channel state information (CSI) can be obtained based on existing channel estimation techniques for RIS assisted channels, such as in [12].…”

Section: A System Modelmentioning

confidence: 99%

Reconfigurable Intelligent Surface Assisted UAV Communication: Joint Trajectory Design and Passive Beamforming

Duo

Yuan

et al. 2020

IEEE Wireless Commun. Lett.

Self Cite

584

335

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Thanks to the line-of-sight (LoS) transmission and flexibility, unmanned aerial vehicles (UAVs) effectively improve the throughput of wireless networks. Nevertheless, the LoS links are prone to severe deterioration by complex propagation environments, especially in urban areas. Reconfigurable intelligent surfaces (RISs), as a promising technique, can significantly improve channel fading effect and enhance communication quality by intelligently reflecting the received signals. Motivated by this, the joint UAV trajectory and RIS's passive beamforming design for a novel RIS-assisted UAV communication system is investigated to maximize the average achievable rate in this letter. To solve the formulated non-convex problem, we divide it into two subproblems, i.e., passive beamforming and trajectory optimization, respectively. We first derive a closed-form phaseshift solution with any given UAV trajectory to achieve the phase alignment of the received signals from different transmission paths. Then, with the given optimal phase-shift solution, we obtain the locally optimal trajectory solution by using the successive convex approximation (SCA) method. Numerical results depict that the proposed algorithm can considerably improve the average achievable rate.Index Terms-UAV communication, trajectory design, reconfigurable intelligent surface, passive beamforming.

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“…Here we assess the accuracy of the approximation using the Kullback-Leibler (KL) divergence. In particular, we consider the KL divergence between the exact PDF of ζ ℓ and its approximated PDF which is defined as D KL = E log fExt(t) fApp(t) [29] where the expectation is taken with respect to the exact probability density function (PDF) of ζ ℓ which can be derived as f Ext (t) = 4tK 0 2t/σ 2 /σ 4…”

Section: B Outage Probabilitymentioning

confidence: 99%

Reconfigurable Intelligent Surface assisted Two–Way Communications: Performance Analysis and Optimization

Atapattu¹,

Fan²,

Dharmawansa³

et al. 2020

Preprint

161

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In this paper, we investigate the two-way communication between two users assisted by a re-configurable intelligent surface (RIS). The scheme that two users communicate simultaneously in the same time slot over Rayleigh fading channels is considered. The channels between the two users and RIS can either be reciprocal or non-reciprocal. For reciprocal channels, we determine the optimal phases at the RIS to maximize the signal-to-interference-plus-noise ratio (SINR). We then derive exact closed-form expressions for the outage probability and spectral efficiency for single-element RIS. By capitalizing the insights obtained from the single-element analysis, we introduce a gamma approximation to model the product of Rayleigh random variables which is useful for the evaluation of the performance metrics in multiple-element RIS. Asymptotic analysis shows that the outage decreases at $\left(\log(\rho)/\rho\right)^L$ rate where $L$ is the number of elements, whereas the spectral efficiency increases at $\log(\rho)$ rate at large average SINR $\rho$. For non-reciprocal channels, the minimum user SINR is targeted to be maximized. For single-element RIS, closed-form solutions are derived whereas for multiple-element RIS the problem turns out to be non-convex. The latter is relaxed to be a semidefinite programming problem, whose optimal solution is achievable and serves as a sub-optimal solution.

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Cascaded Channel Estimation for Large Intelligent Metasurface Assisted Massive MIMO

Cited by 724 publications

References 21 publications

Weighted Sum-Rate Maximization for Reconfigurable Intelligent Surface Aided Wireless Networks

Weighted Sum-Rate Maximization for Reconfigurable Intelligent Surface Aided Wireless Networks

Reconfigurable Intelligent Surface Assisted UAV Communication: Joint Trajectory Design and Passive Beamforming

Reconfigurable Intelligent Surface assisted Two–Way Communications: Performance Analysis and Optimization

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