Analysis of radio propagation with different antenna solutions at sub-THz band in an indoor (tee-junction) environment using ray tracing simulations

The terahertz (THz) and sub-terahertz (Sub-THz) bands are prime candidates for the sixth-generation (6G) wireless communication system, especially for indoor scenarios. In these frequency ranges, key challenges include high propagation loss, substantial molecular absorption, weak diffraction, and the constraint of restricted transmit power despite broad bandwidths. The considerable bandwidth available at the sub-THz band makes it an appealing and enticing option. However, the challenges mentioned earlier pose difficulties in deploying sub-THz systems. Therefore, it is imperative to conduct thorough radio propagation studies to assess the feasibility and deployment possibilities of communication systems operating in the sub-THz frequency range. One of the targets of this work is to precisely identify channel variations at the sub-THz band, and then compare the performance of different antenna solutions at the receiving end in coping with those variations. In this regard, we carried out a comprehensive campaign of ray tracing simulations considering both line-of-sight (LOS) and non-LOS (NLOS) conditions in an indoor scenario. Our internally developed 3D ray tracing tool was calibrated and validated through measurements before being employed for this research work. Ray tracing techniques can deliver results with high accuracy and precision; however, they have substantial computational complexity, and that restricts the scalability of simulations. In this research work, a realistic scenario of the user walking through the tee-junction of the corridor is considered, while being served by the transmitter located in the other wing of the corridor. This article mainly evaluates the coverage aspects of the indoor network employing different antenna solutions at the receiver, i.e., a single fixed beam antenna, an ideal adaptive antenna with beam steering capability, and a switched beam antenna (SBA), at a sub-THz frequency of 100 GHz. We evaluate the impact of different beam pointing error for adaptive antennas and the number of overlapping beams for SBAs, on the received signal power level. The acquired results reveal that in the case of an ideal adaptive antenna, an almost 20 dB signal power is lost while migrating from 3.5 GHz to 26.5 GHz, followed by an additional 14.5 dB loss when transiting from 26.5 GHz to 100 GHz. The findings presented in this article establish a foundation for future investigations of wireless systems in the sub-THz frequency range.