Reconfigurable Intelligent Surface-Assisted Multi-Cell MISO Communication Systems Exploiting Statistical CSI

Luo, Caihong; Li, Xiao; Jin, Shi; Chen, Yijian

doi:10.1109/lwc.2021.3100427

Cited by 33 publications

(17 citation statements)

References 19 publications

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“…Note that it is quite difficult to optimize the ergodic sum SE due to the lack of a closed-form expression. In this section, we apply the ergodic SE approximation obtained in [8], and investigate the beamforming design and user scheduling based on this approximation.…”

Section: Beamforming Design and User Schedulingmentioning

confidence: 99%

“…Given that a RIS is a passive structure composed of a large number of reflection units, it is difficult to obtain the instantaneous perfect CSI. To solve this problem, [8,9] used statistical channel information to design the phase shift or precoding vector. Note that, although the transmission design for RIS assisted systems has been widely considered, the research on the correspoding user scheduling problem involved in RIS assisted communication systems has been scarcely investigated.…”

Section: Introductionmentioning

confidence: 99%

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Joint User Scheduling and Phase Shift Design for RIS Assisted Multi-Cell MISO Systems

Jiang

Matthaiou

et al. 2023

IEEE Wireless Commun. Lett.

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This paper investigates the joint user scheduling and phase shift design for reconfigurable intelligent surface (RIS) assisted multi-cell downlink systems. A closed-form ergodic sum spectral efficiency (SE) approximation is utilized as the optimization metric. Based on this approximation, we schedule the users, whose cascaded channels are mostly correlated with each other's, to maximize each user's effective signal. Moreover, the RIS phase shift is designed to be the mean of the scheduled users' cascaded channel phases. With the proposed transmission design, we find the optimal RIS deployment to achieve the highest maximum throughput which depends only on the relative locations of the BSs and RIS. In addition, we consider a more practical discrete RIS phase shift design based on a discrete Fourier transform (DFT) codebook. Simulation results show that the proposed low-complexity scheduling algorithm performs well.

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Section: Beamforming Design and User Schedulingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Joint User Scheduling and Phase Shift Design for RIS Assisted Multi-Cell MISO Systems

Jiang

Matthaiou

et al. 2023

IEEE Wireless Commun. Lett.

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“…where e x = [1, 0, 0] denotes the unit vector along the x-axis, which is also the normal vector of each IRS element placed on the y-z plane. Based on the channel gain model in (12), the channel coefficient between the (isotropic) AP antenna and the (n y , n z )-th IRS element in g 0 is given by…”

Section: And We Define ξmentioning

confidence: 99%

“…3 Moreover, for simplicity, we assume the channel between the IRS and user 2 is LoS-dominant. Similar to (12), the channel power gain between user 2 and the (n y , n z )-th IRS element is given by…”

Section: B Performance Analysismentioning

confidence: 99%

“…In Fig. 5, we plot the average channel gain ̺ 2 ḡ1 for the IRS-reflected link versus the number of IRS elements per dimension, N. For comparison, we consider the free-space path loss model (without accounting for the projected aperture) and the far-field propagation model (with the uniform-plane wave model) for the AP-IRS channel, by replacing (12) with a ny,nz = A 4πr 2 ny ,nz and a ny,nz = A 4πr 2 , respectively. The asymptotic gain limit of ̺ 2 ḡ1 given in ( 18) is also shown in the figure.…”

Section: A Transmit Diversity Performancementioning

confidence: 99%

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Simultaneous Transmit Diversity and Passive Beamforming with Large-Scale Intelligent Reflecting Surface: Far-Field or Near-Field?

Zheng¹,

Zhang²

2022

Preprint

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Intelligent reflecting surface (IRS) has emerged as a cost-effective solution to enhance wireless communication performance via passive signal reflection. Existing works on IRS have mainly focused on investigating IRS's passive beamforming/reflection design to boost the communication rate for users assuming that their channel state information (CSI) is fully or partially known. However, how to exploit IRS to improve the wireless transmission reliability without any CSI, which is typical in highmobility/delay-sensitive communication scenarios, remains largely open. In this paper, we study a new IRS-aided communication system with the IRS integrated to its aided access point (AP) to achieve both functions of transmit diversity and passive beamforming simultaneously. Specifically, we first show an interesting result that the IRS's passive beamforming gain in any direction is invariant to the common phase-shift applied to all of its reflecting elements. Accordingly, we design the common phase-shift of IRS elements to achieve transmit diversity at the AP side without the need of any CSI of the users. In addition, we propose a practical method for the users to estimate the CSI at the receiver side for information decoding. Meanwhile, we show that the conventional passive beamforming gain of IRS can be retained for the other users with their CSI known at the AP. Furthermore, we derive the asymptotic performance of both IRS-aided transmit diversity and passive beamforming in closed-form, by considering the large-scale IRS with an infinite number of elements. Numerical results validate our analysis and show the performance gains of the proposed IRS-aided simultaneous transmit diversity and passive beamforming scheme over other benchmark schemes.

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RIS-assisted MIMO secure communications with Bob's statistical CSI and without Eve's CSI

Zhang

Cai

et al. 2023

Digital Communications and Networks

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Reconfigurable Intelligent Surface-Assisted Multi-Cell MISO Communication Systems Exploiting Statistical CSI

Cited by 33 publications

References 19 publications

Joint User Scheduling and Phase Shift Design for RIS Assisted Multi-Cell MISO Systems

Joint User Scheduling and Phase Shift Design for RIS Assisted Multi-Cell MISO Systems

Simultaneous Transmit Diversity and Passive Beamforming with Large-Scale Intelligent Reflecting Surface: Far-Field or Near-Field?

RIS-assisted MIMO secure communications with Bob's statistical CSI and without Eve's CSI

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