# Path Loss Measurements and Model Analysis in an Indoor Corridor Environment at 28 GHz and 38 GHz
## 2 Literature Review
The results revealed that big aperture antennas had greater guided wave effects than those with narrow apertures, resulting in a more accurate path loss model for the latter. The measurements also showed that positioning an omnidirectional antenna in the access point (AP) in the center of the meeting room provided better radiation than placing it in a corner because the shadowing effect produced by human obstruction was reduced. These findings will aid in the deployment of new wireless local and personal area networks. Further research work included compiling a comprehensive overview of 5G network approaches in millimeter wave wireless communication systems, as well as bringing together essential millimeter wave propagation models from the past to the present. It also emphasized the significance of developing diverse models based on ray tracing and measuring procedures for current and future uses in academia and industries. As millimeter wave is still in the research era, especially in the application for 5G propagation [37], the data acquired on shadowing and path loss will aid in the predicted improvement. The major issues with millimeter wave propagation, such as limited beam width, high penetration loss, and strong path loss, were highlighted in [25]. The authors also discussed the differences between analytical modeling and ray tracing approaches for channel modeling. After the measurements, data processing and analysis of the measurement results were given, including channel gain, scatterer identification, RMS delay spread, and average power delay profile (APDP). When taking measurements in varied settings, however, the usage of a MIMO channel with a wide frequency spectrum is essential. [PERSON] et al. [19] discussed the frequency measurements in 14, 18, and 22 GHz frequency bands in an indoor environment. The authors of [19] also presented two path loss prediction models and communication scenario analyses for both NLOS and LOS. The LOS analysis showed that the CI and FI models functioned nearly identically after execution at all frequencies. With the frequencies increasing along the LOS range, the PLE increased significantly in the CI model. It rose from 1.37 to 1.66 for the 14 and 22 GHz frequency bands, respectively; however, the LOS values did not match those of the FSPLE. Due to environmental considerations, the path loss models had symmetrical features at around 180\({}^{\circ}\) AoA. The models, on the other hand, performed better at 30\({}^{\circ}\), 330\({}^{\circ}\), and 180\({}^{\circ}\) AoA. The findings also demonstrated that CI and FI models may be employed reliably in both LOS and NLOS corridor scenarios. The main flaw that needs to be addressed is the adoption of a higher gain antenna to decrease additional path losses to the absolute minimum. In addition, as an extension to the above-mentioned conclusion, the effects of transmitting antenna heights on these parameters were explored in [20]. [PERSON] and [PERSON] [21] recently updated this work, delivering efficient improvements for both the CI and FI path loss models. The major findings showed that, for both LOS and NLOS communication scenarios, the enhanced models beat the standard models. Furthermore, the proposed models have substantially superior stability and sensitivity than standard models, especially in the NLOS condition. By combining these enhanced models with the LOS probability models provided in [24], a generic and accurate model for indoor corridor environments may be obtained. Despite the research on these frequency bands, thorough characterization, analysis, and modeling in these bands remain crucial. This study used the MMSE approach to analyze large-scale path loss models in the 28-38 GHz frequency spectrum in order to reduce the complexities and errors in LOS and NLOS scenarios. Path loss is a phenomenon that occurs when a transmitter's signal is attenuated in the communication channel as a function of the distance traveled as well as the propagation channel characteristics.