BEAMFORMING IN INTELLIGENT ENVIRONMENTS BASED ON ULTRA-MASSIVE MIMO PLATFORMS IN MILLIMETERWAVE AND TERAHERTZ BANDS

Recent techniques utilizing reflectarrays or novel metamaterial-based surfaces to control wireless propagation environments have attracted great attention. While most solutions focus on sub-6 GHz wireless channel to assist in throughput enhancement, these intelligent surfaces have significant potentials in combating the transmission distance limitation and solving the non-line-of-sight transmission problems for the millimeter wave (30-300 GHz) and Terahertz-band (0.3-10 THz) where signal propagation is significantly attenuated in the atmosphere. The Ultra-Massive MIMO (UM MIMO) communication framework has been proposed in such frequency bands, which relies on the plasmonic antenna arrays to realize different operation modes, including anomalous reflection, transmission and reception, among others. In this paper, a joint beamforming scheme is developed based on fractional programming optimization to maximize the spectral efficiency under practical consideration of energy constraints of the UM MIMO communication platform. Numerical results are presented to show the performance comparison with existing solutions.