Channel modeling in terahertz communication systems

The radio frequency band used in today's wireless communication has difficulties in meeting the rapidly increasing need for high-speed data transfer, especially in recent years. In order to overcome this bottleneck, the scientific world aims to reach high data rates by using the frequency band called Terahertz (THz) gap in the electromagnetic spectrum, with the offered wide band. However, since it is new, THz communication is a technique that needs to be researched in many subjects. The channel that THz wireless communication systems encounter, since they are intended to be used in different environments, is one of the priority issues to be examined in terms of the performance of these systems. In this study, first of all, THz channel structures were investigated. THz channels are divided into three classes as outdoor, indoor and chip-scale, depending on the environment in which they are used. The chip-scale communication channel is a very new topic with limited use. Modeling of the outdoor channel is relatively easy since the communication depends on the line of sight, related studies exist in the literature. However, in indoor areas where THz communication systems are planned to be used intensively, the channel is complex due to its multipath structure and studies in the literature are limited. In this study, the path loss in THz channels was investigated first. The frequency selective channel structure because of path loss is remarkable, sub-band gaps without sudden attenuation should be selected for communication. Following, the Ray Tracing technique for indoor multipath channel was adapted to THz channels, and the channel structure formed in different environments was examined with simulations. The simulations have shown that the reflections are ineffective relative to the line of sight due to the strong attenuation of the waves. However, the multipath channel structure results in a frequency selective channel. Finally, the Ray Tracing technique is compared with the Saleh-Valenzuela channel model. As a result of the comparison, it is concluded that, although there are similarities between the two models, the Saleh-Valenzuela model has difficulty in modeling the significant difference between the line of sight and the reflections.