On characterization of angular dispersion and fading statistics of THz communication channels

This paper characterizes the angular dispersion and Second-Order Fading Statistics (SOFS) for sub-THz communication channels in several representative indoor and outdoor environments for different sub-THz frequencies ranging from 125 to 300 GHz. In particular, Level Crossing Rate (LCR) and Average Fade Duration (AFD) are studied by extracting Angle-of-Arrival (AoA) measurements available in the existing open literature considering Rician fading conditions. Key findings include the characterization of angular spread, angular constriction, the direction of maximum fading, and Rice K-factor for the considered angular measurements. Furthermore, the impact of various channel and physical parameters, such as velocity and direction of receiver motion, on the SOFS is thoroughly investigated. It has been observed that the environments that represent a widespread angular profile leads to an elevated LCR. Moreover, specific to sub-THz bands that include a dominant Line-of-Sight (LoS) path and a limited number of diffused scattered Multipath Components (MPCs), the Rice K-factor directly influences the SOFS. The provided analysis is of high significance in the design of various aspects at the physical layer of the communication protocol stack, such as antenna design (elements spacing), modulation, coding, and error correction schemes, especially when adaptive schemes are considered. A notable state-of-the-art application of such SOFS is in the design of Ultra Reliable Low Latency Communication (URLLC) services in Beyond 5G/6G communications.