Reconfigurable Intelligent Surfaces in Challenging Environments: Underwater, Underground, Industrial and Disaster

Abstract

Reconfigurable intelligent surfaces (RISs) have been introduced to improve the signal propagation characteristics by focusing the signal power in the preferred direction, thus making the communication environment 'smart'. The typical use cases and applications for the 'smart' environment include beyond 5G communication networks, smart cities, etc. The main advantage of employing RISs in such networks is a more efficient exploitation of spatial degrees of freedom. This advantage manifests in better interference mitigation as well as increased spectral and energy efficiency due to passive beam steering.Challenging environments (CEs) comprise a range of scenarios, which share the fact that it is extremely difficult to establish a communication link using conventional technology due to many impairments typically associated with the propagation medium and increased signal scattering. Although the challenges for the design of communication networks in such environments are known, there is no common enabler or solution for all these applications. Interestingly, the use of RISs in such scenarios can become such an enabler and a game changer technology. Surprisingly, the benefits of RIS for wireless networking in underwater and underground medium as well as in industrial and disaster environments have not been addressed yet. This paper aims at filling this gap by providing a motivation for the application of RISs in CEs. In addition, novel research challenges to be addressed in this context are discussed.Index Terms-Reconfigurable intelligent surfaces, challenging environments, underground, underwater, industrial, emergency networks, Internet of Things I. INTRODUCTIONR ECONFIGURABLE intelligent surfaces (RISs) is a promising technology, which has been motivated by the increasing demands of wireless networks beyond 5G [1]. RISs are intelligently designed artificial planar structures with reconfigurable properties enabled via integrated electronic circuits. These electronic circuits can be programmed to reflect an impinging electromagnetic (EM) wave in a controlled manner, thus making the communication environment controllable and smart. RISs are manufactured with low-profile and light weight using inexpensive materials and can be deployed on a variety of surfaces, such as facades of buildings, walls, ceilings, etc. [2]. The signal propagation from transmitters to receivers can therefore be assisted by steering the RIS-reflected signals in directions that enhance the signal quality, suppress cochannel interference and consequently improve the spectral efficiency. The corresponding performance gains of RISassisted networks compared to current wireless systems are well-known from the previous works in this domain [3]. Furthermore, co-channel interference can be reduced or avoided by choosing different propagation paths for the interfering signals. This is important in urban environments with dense deployment of terminals, cf. [4].Challenging environment (CE) refers to a communication environment, in which the signal propagati...

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“…Besides, Reconfigurable Intelligent Surfaces (RISs) as revolutionary technology may come to help overcoming the shadowing effect induced by rubble in the scenario. In particular, considering agility and modularity properties in their future design, RIS could become a reliable piece of ground infrastructure even when most of conventional network devices would be heavily impaired in the aftermath of a disaster, thereby creating controllable propagation conditions for the cellular signals employed in the measurement process [7].…”

Simultaneous Control Information and Power Transmission for Reconfigurable Intelligent Surfaces

“…The reconfigurable properties of RIS are enabled via integrated electronic circuits, which can be programmed to reflect an impinging electromagnetic wave in a controlled manner [1]. The benefits of RIS for wireless communication have been analyzed for various scenarios and applications, including 6G [2], smart cities [3], challenging environments [4], satellite communications [5], etc. In these applications, notable improvements in data rate and energy efficiency can be expected.…”