Reconfigurable-Intelligent-Surface-Assisted B5G/6G Wireless Communications: Challenges, Solution, and Future Opportunities

Abstract

The power consumption and hardware cost are two of the main challenges for realizing beyond fifth-generation (B5G) and sixth-generation (6G) wireless communications. Recently, the emerging reconfigurable intelligent surface (RIS) have been recognized as a promising tool for enhancing the propagation environment and improving the spectral efficiency of wireless communications by controlling low-cost passive reflecting elements. However, current cellular communication were designed on the basis of conventional communication theories, significantly restrict the development of RISassisted B5G/6G technologies and lead to severe limitations. In this article, we discuss RIS-assisted channel estimation issues involved in B5G/6G communications including channel state information (CSI) acquisition, imperfect cascade CSI for beamforming design and co-channel interference coordination, and develop a few possible solutions or visionary technologies to promote the development of B5G/6G.Finally, potential research opportunities are discussed.

Performance Analysis and Optimization of Partitioned-IRS Assisted NOMA Network

“…3 Gamma approximation exhibits a closer alignment with the exact PDF when compared to the results obtained using the CLT approximation [14]. 4 The subscript d =1 & e =2 for P = X, and d =2 & e =1 for P = Y .…”

“…NOMA [3] relies on the difference in channel gains to the users. To facilitate this, and improve coverage, use of Intelligent Reflective Surfaces (IRS) has been suggested [4]. An IRS is a planar surface that can control the phase of the reflected signal.…”

A Novel 3D Geometry-Based Propagation Model for RIS-Aided Macrocell High-Speed Railway Communication Environments

“…In [15], the authors provided a two-cluster model in 3D space for massive MIMO channels, which computed the high-speed railway channel propagation characteristics with regards to the distinct delays, i.e., tap properties. Furthermore, in [16] Reconfigurable intelligence surface (RIS), which is a 2D man-made surface consisting of low-cost passive reflecting elements with adjustable electromagnetic responses, is an emerging technology that manipulates the meta-atoms of integrated circuits to realize the propagation environment controllable and programmable [17]- [19]. For digging the benefits of systems for RIS-assisted high-speed railway communications, there is crucial to develop an RIS-assisted V2V propagation model that fully describe the wireless propagation environments [20]- [22].…”

Channel estimation for reconfigurable intelligent surface‐assisted mmWave using multidimensional Runge Kutta orthogonal matching pursuit algorithm in MIMO systems

“…As a result, the millimeter Wave (mmWave) frequency bands are utilized for transmitting data at higher frequencies, offering bandwidths ranging from multiple GHz to multiple Gbps, enabling high‐speed data transmission 4 . However, the mmWave channel experiences path loss due to weak radio signals obstructed by obstacles such as furniture, walls, or trees present between the base station and the user, leading to significant signal degradation 5–7 . RIS are introduced to assist the wave channel.…”

“…4 However, the mmWave channel experiences path loss due to weak radio signals obstructed by obstacles such as furniture, walls, or trees present between the base station and the user, leading to significant signal degradation. [5][6][7] RIS are introduced to assist the wave channel. Designed with electronic circuits control the arriving signals with a wide range of features and are composed of numerous reconfigurable reflecting elements capable of altering the phase of incident signals individually and in a tunable manner.…”