# Path Loss Measurements and Model Analysis in an Indoor Corridor Environment at 28 GHz and 38 GHz
## 2 Literature Review
The effect of path loss on this D2D communication, however, is unique and unsurpassed. Modeling a method that will result in a significant reduction in attenuation is required. The authors in [51] proposed a strategy that uses mode assignment by reuse as well as cellular mode dedication based on a tradeoff of path loss attenuation and ranges between D2D users. This scheme's analysis was compared to other existing schemes, such as the alternate offer bargaining game theory algorithm (AOBG) and the heuristic algorithm. The main benefit of the proposed approach is that the D2D user's SINR threshold is supported to a certain extent. The practicality of this technology is demonstrated by the fact that it is extremely useful in situations where path loss attenuation is a concern in both indoor and outdoor contexts. Another measurement work was conducted in two different locations in the United States of America (USA) by [PERSON]. [PERSON] et al. to check the path loss models for 5G millimeter wave propagation channels in urban microcells using the best of the sliding correlator channel sounder at two frequency bands (28 and 38 GHz). Using directional antennas of varying heights and gains, this experiment investigated multiple microcellular conditions. The linear regression fits were used to create the path loss models. The path loss spanned a distance that depended on the power received, according to the measurements. When compared to existing path loss models, the suggested model performed better in terms of lowering shadow factors by several decibels and providing a better fit to empirical data while permitting only a minor path loss [52]. [PERSON] et al. proposed an indoor localization method based on the path loss--distance relationship using handset sensor data. This proposed model computed the range between the Bluetooth low energy (BLE) transmitter and the smartphone by first using the distance and path loss relationship and then using (PDR) pedestrian dead-reckoning fixed on the mobile phone's accelerometer. When compared to previous methods, the results revealed a significant improvement in the distance error [53]. [PERSON] et al. conducted a comprehensive investigation in which the investigated mmWave propagation models as well as measurements in indoor environments. Time dispersion and path loss were identified as the key indoor wireless channels in terms of millimeter wave propagation. Although the path loss coefficient grew as the frequency increased, the exponent was only affected by the structure and kind of environment, not by the frequency. The overall observation is that CI and FI models are the best for both LOS and NLOS channel propagations in millimeter wave bands, especially in indoor environments, based on multiple applications of different research articles regarding frequency ranges of 28 to 100 GHz. This development represents a significant step forward in the deployment of millimeter wave propagation for both 5G and 6G networks with low propagation losses [17]. To the best of our knowledge, there is no other analysis that covers the peculiarity of the effect of the proximity of walls on path loss parameters. To fill this research gap, one of the main goals of this work was to find an acceptable model with the best line of fit and the simplest application for the path loss model estimation in both LOS and NLOS scenarios. The well-known single-frequency CI and FI path loss models for V-V and V-H antenna polarizations were used to examine the channel characterization. The work also shows that the multipath components added up favorably due to wave-guiding and reflections in the inside corridor environments. Another contribution from this investigation is that the proximity of the walls, the materials of the walls, the floor, and other irregular elements, such as wooden doors, concrete, and elevator doors along the corridor, all have effects on radio wave propagation (indoors).