Beyond 5G RIS mmWave Systems: Where Communication and Localization Meet

Abstract

Upcoming beyond fifth generation (5G) communications systems aim at further enhancing key performance indicators and fully supporting brand-new use cases by embracing emerging techniques, e.g., reconfigurable intelligent surface (RIS), integrated communication, localization, and sensing, and mmWave/THz communications. The wireless intelligence empowered by state-of-the-art artificial intelligence techniques has been widely considered at the transceivers, and now the paradigm is deemed to be shifted to the smart control of radio propagation environment by virtue of RISs. In this paper, we argue that to harness the full potential of RISs, localization and communication must be tightly coupled. This is in sharp contrast to 5G and earlier generations, where localization was a minor additional service. To support this, we first introduce the fundamentals of RIS mmWave channel modeling, followed by RIS channel state information acquisition and link establishment. Then, we deal with the connection between localization and communications, from a separate and joint perspective.

Symbol error probability of mmWave communications with transmit antenna selection and RISs under the impacts of hardware impairments

“…As characterized in the literature, the RISs are made from metasurfaces; thus, their phases are independently tuned. 2,14,28 In addition, a RIS is often equipped with a smart controller, and its phases are discrete. 44 More specifically, the RISs' phases are often not continuous because of hardware limitations.…”

“…By utilizing a high phase resolution so that ℝ w ) 1 and the perfect channel estimation at the RIS controller, the w th RIS can create an ideal/optimal phase * to achieve ξ wt ¼ 0 for all w and t. 2,11,14,28 In other words, it is reasonable to obtain φ wt þ θ isd À ϕ iwt À ψ wt ¼ 0. † Therefore, the phase φ wt of the w th =t th is optimized as…”

“…2,4,13 Since the RISs are often deployed on the top/wall of factories/buildings, they can support mmWave communications to significantly reduce the effects of blocking objects. [14][15][16] In particular, the design of beamforming and reflecting coefficients was proposed to enhance the performance of RISs-assisted mmWave communications. Additionally, RIS-oriented mmWave design has shown great promise in overcoming the limitations of traditional beamforming techniques, providing more flexible and adaptable wireless connectivity.…”

A Broadband 1-Bit Single-Layer Reconfigurable Reflectarray Unit Cell Based on PIN Diode Model

“…Indeed, each cell in RRAs using varactors is controlled independently by a circuit that includes a digital-to-analog converter (DAC) and some passive devices besides register shifters, microcontrollers (MCUs), or FPGAs [22], [23], which makes the control board extremely complicated and high-cost, especially when using fast-settling ADCs such as MAX5592. This problem is more critical for array with hundreds or thousands of elements which are employed for 5G [24], 6G [14], [25] and satellite [26], [27], [28], [29]. Of a particular note, PIN diodes are preferred for RRAs given their low cost, diversity, and ready availability on the market [22], [23], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40].…”

Low-profile frequency-reconfigurable antenna for 5G applications

“…The 5G of mobile technology is built on the foundation of millimeter waves, and it is envisaged that these waves will play a important role in mobile communication. Many businesses and economic sectors will use this technology because of its vast characteristics [6], [7]. For all of the ever-growing gadgets, 5G is intended to provide an enormous network foundation.…”