Robust Channel Estimation for RIS-Aided Millimeter-Wave System With RIS Blockage

Ma, Siqi; Shen, Wenqian; Gao, Xinyu; An, Jianping

doi:10.1109/tvt.2022.3153966

Cited by 16 publications

(3 citation statements)

References 20 publications

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“…When an electromagnetic wave interacts with an RIS, it can adjust the reflected beam direction, change the amplitude and phase of the signal, and even generate a wavefront-shaping effect in real time, thereby achieving dynamic adjustment and optimization of the signal. Thus, an RIS can improve signal coverage, increase the reliability of communication, enhance privacy security, and significantly improve the energy efficiency of wireless communication systems [22].…”

Section: Introductionmentioning

confidence: 99%

5G Reconfigurable Intelligent Surface TDOA Localization Algorithm

Liu,

Zhang

2024

Electronics

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In everyday life, 5G-based localization technology is commonly used, but non-line-of-sight (NLOS) environments can block the propagation of the localization signal, thus preventing localization. In order to solve this problem, this paper proposes a reconfigurable intelligent surface non-line-of-sight time difference of arrival (TDOA) localization (RNTL) algorithm. Firstly, a model of a reflective-surface-based intelligent localization (RBP) system is constructed, which utilizes multiple RISs deployed in the air to reflect signals. Secondly, in order to reduce the localization error, this paper establishes the optimization problem of minimizing the distance between each estimated coordinate and the actual coordinate and solves it via the piecewise linear chaotic map–gray wolf optimization algorithm (PWLCM-GWO). Finally, the simulation results show that the RNTL algorithm significantly outperforms the traditional gray wolf optimization and particle swarm optimization algorithms in different signal-to-noise ratios, and the localization errors are reduced by 46% and 53.5%, respectively.

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Section: Introductionmentioning

confidence: 99%

5G Reconfigurable Intelligent Surface TDOA Localization Algorithm

Liu,

Zhang

2024

Electronics

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“…Studies have delved into diverse deployment scenarios and investigated a wide range of system parameters and performance metrics. These include the potential of RISs in massive MIMO systems, their role in enhancing millimetre-wave communications, and their impact on energy efficiency, among others [25][26][27]. However, despite these strides, there remains considerable scope for further exploration, particularly in the realm of robust optimization methods.…”

Section: Introductionmentioning

confidence: 99%

Enhancing active reconfigurable intelligent surface

Khalil¹

2023

Preprint

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<p> A Reconfigurable Intelligent Surface (RIS) panel comprises many independent Reflective Elements (REs). One possible way to implement an RIS is to use a binary passive load impedance connected to an antenna element to achieve the modulation of reflected radio waves. Each RE reflects incoming waves (incident signal) by using on/off modulation between two passive loads and adjusting its phase using a Phase Shifter (PS). However, this modulation process reduces the amplitude of the reflected output signal to less than unity. Therefore, recent RIS works have employed Reflection Amplifiers (RAs) to compensate for the losses incurred during the modulation process. However, these systems only improve the reflection coefficient for a single modulation state, resulting in suboptimal RE efficacy. Thus, this paper proposes a strategy for optimising RE by continuously activating the RA regardless of the switching load state. The performance of the proposed scheme is evaluated in two scenarios: (1) In the first scenario (Sc1), the RA only operates to compensate for high-impedance loads, and (2) in the second scenario (Sc2), the RA runs continuously regardless of the RE loads. To benchmark the performance of Sc1 and Sc2, various metrics are compared, including signal-to-noise ratio, insertion loss, noise figure, communication range, and power-added efficiency. Numerical examples are provided to demonstrate the effectiveness of the proposed scheme. It is found that the proposed system in Sc2 leads to better overall performance compared to Sc1 due to the increased gain of the RIS reflection.</p>

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“…Also, mmWave networks use large antenna arrays both at the transmitter and receiver to compensate for the higher path loss, which makes the channel estimation even more difficult for RIS-enabled mmWave networks [8]. Moreover, the signaling overhead associated with acquiring perfect CSI is very high for RIS-enabled mmWave networks because the corresponding channel matrices are extremely large due to the presence of an intermediate RIS [9,10]. Since a RIS itself cannot estimate the channel, the BS (in case of a downlink) performs the estimation for the endto-end communication channel through feedback links, which results in large delays and higher complexity [11].…”

Section: Introductionmentioning

confidence: 99%

On the Effective Capacity of RIS-enabled mmWave Networks with Outdated CSI

Haider Shah,

Pavan Deram,

Widmer

2023

IEEE INFOCOM 2023 - IEEE Conference on Computer Communications

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Reconfigurable intelligent surfaces (RISs) have great potential to improve the coverage of mmWave networks; however, acquiring perfect channel state information (CSI) of a RISenabled mmWave network is very costly and should thus be done infrequently. At the same time, finding an optimal RIS configuration when CSI is outdated is challenging. To this end, this work aims to provide practical insights into the tradeoff between the outdatedness of the CSI and the system performance by using the effective capacity as analytical tool. We consider a RIS-enabled mmWave downlink where the base station (BS) operates under statistical quality-of-service (QoS) constraints. We find a closed-form expression for the effective capacity that incorporates the degree of optimism of packet scheduling and correlation strength between instantaneous and outdated CSI. Moreover, our analysis allows us to find optimal values of the signal-to-interference-plus-noise-ratio (SINR) distribution parameter and their impact on the effective capacity in different network scenarios. Simulation results demonstrate that better effective capacity can be achieved with suboptimal RIS configuration when the channel estimates are known to be outdated. It allows us to design system parameters that guarantee better performance while keeping the complexity and cost associated with channel estimation to a minimum.

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Robust Channel Estimation for RIS-Aided Millimeter-Wave System With RIS Blockage

Cited by 16 publications

References 20 publications

5G Reconfigurable Intelligent Surface TDOA Localization Algorithm

5G Reconfigurable Intelligent Surface TDOA Localization Algorithm

Enhancing active reconfigurable intelligent surface

On the Effective Capacity of RIS-enabled mmWave Networks with Outdated CSI

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