H.R.D. Filgueiras, T. H. Brandão, L.G. da Silva, A. Cerqueira S. Jr.
National Institute of Telecommunications,
Keywords: 5G, 6G, Antenna Systems, antenna array, MIMO
Summary:The fifth generation of mobile communication (5G) has been recently commercially implemented in its first release, Release 15, which focused on enhanced mobile broadband (eMBB). Release 16 and 17, on the other hand, are focused on ultra-reliable and low-latency (URLLC) and massive machine-type communications (mMTC). Beyond 5G, the sixth generation (6G) is a vision for the 2030s, which will require a much wider and holistic approach to identify the system needs, aiming for application-as-a-service for human and non-human users. Some research groups are defending five potential 6G scenarios: Further eMBB (FeMBB); enhanced URLLC (eURLLC); ultra mMTC (umMTC); long-distance and high-mobility communication (LDHMC); extremely low-power communication (ELPC). Basically, they are a direct evolution from 5G, but with more restrictive system requirements. Antenna development is one of the most important challenges to accomplish those requirements since connectivity needs to be seamless, flexible, and enable high throughout. Our Laboratory Wireless and Optical Convergent Access (WOCA) research group has intensely contributed to developing millimeter and sub-millimeter wave antennas for 5G and beyond in the past few years. We can split the antennas into categories applied to transport and access networks. Our group has introduced a dual-band Focal-point/Cassegrain antenna aiming for high-throughput fronthauls, which takes advantage of a frequency selective surface (FSS)-based sub-reflector to enable simultaneous operation in 7.5 and 28 GHz using one 60-cm main reflector. The antenna has been implemented in an innovative 5G-Xhaul fiber-wireless architecture, reaching up to 18 Gbit/s throughput following the 3GPP requirements. Furthermore, we have developed a low-profile and high-gain slotted waveguide antenna array (SWAA) for point-to-point links and self-backhaul applications with six pairs of metal grooves to obtain 27.7 dBi-gain without using parabolic reflectors. Both of them can be applied to provide throughput to mobile cells, in which we can highlight some access-focused antenna development as well, including: 12 to 15-dBi gain omnidirectional antennas operating in the 26-GHz band with new approach for slot design aiming for wide bandwidth (trapezoidal slots); simultaneous operation at both 28 and 38 GHz bands in two distinct sectors and scalable for N-order antenna array applied to switched-beam applications; 64-element slot-based antenna array for fully digital and TDD-based massive multiple-input multiple-output (mMIMO) systems; tri-band (700 MHz, 3.5 GHz and 26 GHz) solution embedded in the same antenna system for high throughput and flexibility on heterogeneous networks; reconfigurable intelligent surface (RIS) for beamforming and beam steering applications with 1024 elements at 24.5 GHz targeting integrated access backhaul (IAB) applications. The obtained results have proved the applicability of multiple antenna and antenna arrays applied to next-generation mobile networks operating, mainly in mmWaves. The abstract started with a brief overview of mobile communication trends. Then, we conducted a discussion on the state-of-the-art antenna design previously designed by our group, in which it were presented antennas applied to both transport and access networks using multiple innovative technologies for increasing gain and bandwidth or enabling multi-band and mMIMO applications.