\begin{tabular}{|c|}
\hline
Table \\ [2ex]
\hline\hline
A precoding-aided RIS scheme is considered for multi-user downlink transmission.
Maximization of sum-rate and energy efficiency is performed with finite resolution reflectors. \\
\hline
The problem of joint active and passive beamformer design is investigated for a MISO multi-user system.
Minimization of the BS transmit power is performed through optimization and square-law scaling in transmit power is demonstrated. \\
\hline
A mathematical framework is proposed for the calculation of the average SEP of RIS (LIS)-assisted systems.
The concept of using the RIS as an AP (transmitter) is also introduced. \\
\hline
The concept of RIS (LIS)-assisted IM is proposed by considering the RIS as an AP.
Greedy and maximum likelihood detectors are formulated for LIS-SM and LIS-SSK schemes along with theoretical derivations. \\
\hline
The maximization of the minimum SINR is investigated for an RIS-assisted multi-user MISO system.
Rank-one and full-rank LOS channels, correlated RIS channels, and large-scale fading statistics are considered for phase optimization. \\
\hline
The problem of optimal transmit beamformer and RIS phase shifter is investigated to maximize the achievable spectral efficiency.
It has been shown that the proposed algorithms guarantee locally optimal solutions. \\
\hline
An RIS-assisted large-scale MISO system is considered with Rician fading.
Ergodic capacity of the system is maximized by the optimization of LIS phases. \\
\hline
A new channel estimation protocol for an RIS-assisted MISO system with energy harvesting is proposed.
Active and passive near-optimal beamforming designs are formulated to enable efficient power transfer. \\
\hline
A new RIS architecture based on sparse channel sensors, in which some of the existing RIS units are active, is proposed.
Two separate methods, based on compressive sensing and deep learning, are considered for the RIS design. \\
\hline
Considered the problem of cascaded channel estimation with fully passive RIS elements.
An RIS-assisted massive multi-user MIMO system is considered and a three-stage channel estimation algorithm is proposed. \\
\hline
An RIS-assisted secure communication system with a legitimate receiver and an eavesdropper is considered.
Showed that increasing the number of RIS reflecting elements is more beneficial than increasing the number of antenna elements at BS. \\
\hline
A downlink MISO broadcast system with multiple legitimate receivers and eavesdroppers is considered.
A minimum-secrecy-rate maximization problem is formulated by jointly optimizing the BS beamformer and RIS reflecting coefficients \\ [5ex]
\hline
\end{tabular}
答案1
您需要使用允许自动换行的列类型。（提示：c列类型不允许。）下面，我使用一个tabularx环境（由包提供tabularx），将其宽度设置为\textwidth，并使用单列布局以及X自动使其内容居中的列类型版本。
\documentclass{article} % or some other suitable class
\usepackage{tabularx} % for 'X' column type
\newcolumntype{C}{>{\centering\arraybackslash}X}
\begin{document}
\setlength\extrarowheight{2pt}
\noindent
\begin{tabularx}{\textwidth}{|C|}
\hline
Table \\[2ex]
\hline\hline
A precoding-aided RIS scheme is considered for multi-user downlink transmission.
Maximization of sum-rate and energy efficiency is performed with finite resolution reflectors. \\
\hline
The problem of joint active and passive beamformer design is investigated for a MISO multi-user system.
Minimization of the BS transmit power is performed through optimization and square-law scaling in transmit power is demonstrated. \\
\hline
A mathematical framework is proposed for the calculation of the average SEP of RIS (LIS)-assisted systems.
The concept of using the RIS as an AP (transmitter) is also introduced. \\
\hline
The concept of RIS (LIS)-assisted IM is proposed by considering the RIS as an AP.
Greedy and maximum likelihood detectors are formulated for LIS-SM and LIS-SSK schemes along with theoretical derivations. \\
\hline
The maximization of the minimum SINR is investigated for an RIS-assisted multi-user MISO system.
Rank-one and full-rank LOS channels, correlated RIS channels, and large-scale fading statistics are considered for phase optimization. \\
\hline
The problem of optimal transmit beamformer and RIS phase shifter is investigated to maximize the achievable spectral efficiency.
It has been shown that the proposed algorithms guarantee locally optimal solutions. \\
\hline
An RIS-assisted large-scale MISO system is considered with Rician fading.
Ergodic capacity of the system is maximized by the optimization of LIS phases. \\
\hline
A new channel estimation protocol for an RIS-assisted MISO system with energy harvesting is proposed.
Active and passive near-optimal beamforming designs are formulated to enable efficient power transfer. \\
\hline
A new RIS architecture based on sparse channel sensors, in which some of the existing RIS units are active, is proposed.
Two separate methods, based on compressive sensing and deep learning, are considered for the RIS design. \\
\hline
Considered the problem of cascaded channel estimation with fully passive RIS elements.
An RIS-assisted massive multi-user MIMO system is considered and a three-stage channel estimation algorithm is proposed. \\
\hline
An RIS-assisted secure communication system with a legitimate receiver and an eavesdropper is considered.
Showed that increasing the number of RIS reflecting elements is more beneficial than increasing the number of antenna elements at BS. \\
\hline
A downlink MISO broadcast system with multiple legitimate receivers and eavesdroppers is considered.
A minimum-secrecy-rate maximization problem is formulated by jointly optimizing the BS beamformer and RIS reflecting coefficients. \\
\hline
\end{tabularx}
\end{document}