# Path Loss Measurements and Model Analysis in an Indoor Corridor Environment at 28 GHz and 38 GHz
## 1 Introduction
Despite the fact that millimeter wave technology has been in use for some time, with the advent of process technology, this technique has begun to receive widespread acceptance among academics and industries. After building a communication channel that spans the capacity and dependability of data rates, the path loss exponent is one major metric that a good communication channel depends on [1; 4; 13; 14]. Path loss is a measure of the degeneration of the propagated signals over a distance range in both line-of-sight (LOS) and non-line of sight (NLOS) scenarios. The path loss exponent is used to evaluate the performance of a communication system in wireless channel propagation. It has been found that impediments, including walls, furniture, and people, can cause propagation loss in millimeter wave technology. The development of a good path loss prediction model for these bands still depends on detailed characterization, analysis, and modeling in these frequency bands, despite the fact that research in this field is ongoing. Wireless system design, planning, and simulation were all part of the model application. Different path loss model concepts have been proposed by various academics for examination, particularly in indoor environments [15; 16; 17; 18; 19; 20; 21]. The most important use of path loss models will be in [18], where calculations of power budgets, modulations, forecasts of cellular coverage/interferences, and the design of coding schemes are all highly critical. This study, which offers LOS and NLOS measurement data scenarios in an indoor corridor environment, assesses CI and FI path loss prediction models for frequency ranges of 28 and 38 GHz. The measuring campaign took place on the 5 th floor of the Discipline of Electrical, Electronic, and Computer Engineering Department building at the University of KwaZulu- Natal's Howard Campus in Durban, South Africa. In the NLOS scenario, the evaluation included propagation characteristics for both FI and CI free space path loss models. [PERSON] and [PERSON] [22] worked on the same channel settings of 14 and 22 GHz using the Rohde & Schwarz SMF 100A for signal generation at the transmitter (Tx), Rohde & Schwarz FSIQ signal analyzer at the receiver (Rx), and two directional pyramidal horn antennas. Previous work of [18] did not consider the behaviors of the model parameters when two antenna polarizations were used but dwelled only on one antenna polarization, which was the V-V antenna polarization in an indoor environment. However, to fill this gap, this paper evaluated the measurement analysis of the existing CI together with the FI path loss models in terms of the antenna polarizations using measured data from the measurement campaign. The measurement campaign was conducted at frequency bands of 28 and 38 GHz using the Rhode and Schwarz SMB 100A radio signal generator to generate continuous wave (CW) signals, which were then delivered across a wireless medium to the Rhode and Schwarz FSIQ 40 signal analyzer of a frequency range of 100 KHz to 40 GHz with the use of broadband horn antennas at both the transmitter and receiver ends. The accuracy, simplicity, and stability of the parameters of the models were evaluated in both LOS and NLOS scenarios. This work established an appropriate antenna polarization mode with the lowest path loss when transmitting power from the transmitter to the receiver in both LOS and NLOS communication scenarios. It will also be a good indication for developmental initiatives for future wireless communication research on specific building design prediction path loss models for brick and concrete walls (since the indoor corridor is made of dry concrete and bricks). The rest of the paper is organized as follows: Section 2 reviews the literature studiesand works on millimeter waves. Details of the environment used for the measurement campaign and various path loss models are discussed in Section 3. The results and the comprehensive discussion of the results are presented in Section 4. The concluding remarks are presented in Section 5.