Shannon Wireless’ Post

In this manuscript, the authors present a novel approach to jointly optimize active and passive beamforming in a #multiple-#input-#multiple-#output (#MIMO) #full-#duplex (#FD) system assisted by an #intelligent #reflecting #surfaces (#IRS) for #weighted #sum #rate (#WSR) maximization. Given the inherent difficulty in obtaining perfect #channel #state #information (#CSI) in practical scenarios, They consider imperfect CSI and propose a statistically robust beamforming strategy to maximize the ergodic WSR. ---- Chandan Kumar Sheemar, Sourabh Solanki, Jorge Querol, Sumit Kumar, Symeon Chatzinotas More details can be found at this link: https://lnkd.in/euMd5AfJ

This paper examines using #reconfigurable #intelligent #surfaces (#RIS) to allow multiple user pairs to communicate at the same time over the same wireless channel. The authors propose using optimization on a #Riemannian #manifold to configure the passive reflection coefficients of the RIS. The goal is to minimize the total interference while dealing with constraints where the coefficients have a constant magnitude. ---- Mohamed Ali More details can be found at this link: https://lnkd.in/g9UNb8Vn

#Intelligent #reflecting #surfaces (#IRS) have emerged as a promising technology of managing the radio signal propagation by relying on a large number of low-cost passive reflecting elements. In this letter, the optimal #pilot #power #allocation required for accurate #channel #estimation of IRS-assisted communication systems is investigated. In contrast to conventional channel estimators, where pilot signals are usually designed to be constant-enveloped, the authors reconsider the pilot design to improve the passive beamforming performance thus resulting in an improved achievable rate. At first sight the result of their analysis appears counter-intuitive, suggesting that at a given total power, more power should be allocated to estimate low-gain channels, since the channel phase impairments are more severe than those of high-gain channels. ---- Jiancheng An, Li Wang, Chao Xu, Lu Gan, Lajos Hanzo More details can be found at this link: https://lnkd.in/erjaKMzn

#Intelligent #reflecting #surfaces (#IRS) have emerged as a promising technology of managing the radio signal propagation by relying on a large number of low-cost passive reflecting elements. In this letter, the optimal #pilot #power #allocation required for accurate #channel #estimation of IRS-assisted communication systems is investigated. In contrast to conventional channel estimators, where pilot signals are usually designed to be constant-enveloped, the authors reconsider the pilot design to improve the #passive #beamforming performance thus resulting in an improved achievable rate. At first sight the result of their analysis appears counter-intuitive, suggesting that at a given total power, more power should be allocated to estimate low-gain channels, since the channel phase impairments are more severe than those of high-gain channels. ---- Jiancheng An, Li Wang, Chao Xu, Lu Gan, Lajos Hanzo More details can be found at this link: https://lnkd.in/erjaKMzn

This paper proposes a #control and #frequency #allocation #method for #intelligent #reflecting #surfaces (#IRSs) that can support #multiple #users simultaneously without reducing the frequency efficiency by effectively utilizing a #beam #squint. Specifically, the proposed method #maximizes the #frequency #efficiency by controlling the IRS reflection direction, reflected beam width, and resource block allocation to #user #equipment (#UE), exploiting the shift in the reflection direction caused by the beam squint. In this study, they evaluated the proposed method with #regard to #frequency #efficiency and simultaneous multipleconnection performance through simulations.----@Yuichi Kawamoto, @Ei Tanaka, Dr. Shikhar Verma, Nei Kato, @Masashi Iwabuchi, @Riku Ohmiya, Yoghitha Ramamoorthi, @Tomoki Murakami More details can be found at this link: https://lnkd.in/g_c5vzAe

This paper proposes a new #reconfigurable #intelligent #surfaces (#RIS) channel estimation technique, which is the first one that performs #minimum #mean #square #error (#MMSE) based interpolation for the sake of taking into account the time-varying nature of fading even within the coherence time. The RIS modeling invokes only passive elements without relying on RF chains, where both the direct link and RIS-reflected links, as well as both the #line-#of-#sight (#LoS) and #non-#LoS (#NLoS) paths, are taken into account. ----Jiancheng An, Shinya Sugiura, Lajos Hanzo More details can be found at this link: https://lnkd.in/gUarVc9B

In this paper, the authors ask ourselves the question: Would it be feasible to remove the need for control channels for #Reconfigurable #Intelligent #Surfaces (#RISs)? They analyze the feasibility of devising Self-Configuring Smart Surfaces that can be easily and seamlessly installed throughout the environment, following the new #Internet-#of-#Surfaces (#IoS) paradigm, without requiring modifications of the deployed mobile network. To this aim they design #MARISA, a self-configuring metasurfaces absorption and reflection solution. Their results show that MARISA achieves outstanding performance, rivaling with state-of-the-art control channel-driven RISs solutions. ---- Antonio Albanese, Francesco Devoti, Vincenzo Sciancalepore, Marco Di Renzo, Xavier Costa Pérez More details can be found at this link: https://lnkd.in/euTxwgpX

This work investigates a #Holographic #Multiple-#Input #Multiple-#Output (#HMIMO) communication system consisting of a source and a receiver being #two #surfaces in the #LoS #configuration. The closed-form expressions of the electric field and the channel coupling coefficients are obtained leveraging an asymptotic expansion of the Green’s function. The derived approximations show satisfactory accuracy in both #near-#and #far-#field conditions, across low and high frequencies. These are then employed to obtain insights regarding (i) the #spatial #distribution of the #beams, and (ii) the #mapping #relation between #source and #receiver modes while ensuring sufficient orthogonality under prescribed conditions. ----Giovanni Iacovelli, @Claudio Iacovelli, Symeon Chatzinotas More details can be found at this link: https://lnkd.in/gKarga8n

#Reconfigurable #intelligent #surfaces (#RIS) have the potential to enable high-frequency wireless systems that could become essential for applications requiring high reliability and data rates. However, these systems are sensitive to #misalignment of components and #atmospheric #phenomena such as #turbulence. Motivated by this, this paper presents a theoretical framework for statistically characterizing the combined effects of cascaded turbulence and misalignment in channels. Specifically, it provides the probability density and cumulative distribution functions for channels experiencing both turbulence and misalignment together. ---- Alexandros-Apostolos A. Boulogeorgos More details can be found at this link: https://lnkd.in/gZjEZ28Z

This paper proposes a new wireless communication system aided by multiple active and passive #reconfigurable #intelligent #surfaces (#RISs). A number of active and passive RISs are deployed to assist communication between a base station (BS) and a remote user by establishing a #multi-#hop reflection path across the active and passive RISs. Specifically, the active RISs can opportunistically amplify the reflected signal along the multi-reflection link. An optimization problem is formulated to maximize the achievable rate of a typical user by designing the active-and-passive RIS routing path. ---- Yunpu Zhang More details can be found at this link: https://lnkd.in/eqdC8DXW