Reconfigurable intelligent surfaces: A promising frontier for future generations of wireless technology

The rapid advancement of wireless technologies has completely transformed the way we live, work, and connect with others. With the commercialization of 5G, researchers are now pushing the boundaries even further, developing the next generations, often referred to as beyond 5G (B5G) and 6G. B5G and 6G are poised to provide even higher data rates, capacities, and reliabilities; lower latency; and greater connectivity than the current 5G. To meet these stringent requirements, future wireless generations are expected to populate higher frequency bands, such as millimeter-wave and subterahertz bands. However, in these frequency ranges, a major challenge awaits. The wireless communications in these bands are expected to rely on the line-of-sight (LoS) path. Due to the shorter wavelength, a simple obstacle, such as a wall, tree, or even a human standing between the transmitter and receiver, can significantly degrade the communication quality. To tackle this issue, reconfigurable intelligent surfaces (RISs) have risen as a promising technology that could become the key to future communications. Comprising low-cost, low-complexity, passive elements, an RIS is able to manipulate the electromagnetic wave properties, allowing one to realize a smart wireless environment. An RIS is capable of beam steering and beam forming, creating a virtual LoS when no LoS exists between the transmitter and receiver. This brief article discusses the RIS technology and its promising features for the future of wireless communications.