# Path Difference Optimization of 5G Millimeter Wave Communication Networks in Malaysia
## 6 Simulation Results  
Millimeter-wave propagation can be influenced by different propagation paths, such as LOS and NLOS, different regions, including indoor, outdoor, highway, urban, semi-urban, and rural areas, and different weather conditions, such as rain, fog, snow, dust, and sand. Several path loss models [32] are considered in our investigation of the impact of heavy and frequent rainfall on propagating mmWave signals in the Malaysia region. In this paper, we focus on LOS and NLOS propagation paths in the outdoor region with rain attenuation. Path attenuation depends on the operating frequency, path difference, and rainfall intensity. Equation (3) is used to estimate the path attenuation due to rainfall in terms of the path difference and operating frequency. Path attenuation is estimated for various mmWave frequencies (10 GHz to 100 GHz) using the ITU-R model at 0.01% of the time of the rainfall rate. We used MATLAB R2019a software to estimate the rain attenuation, LOS and NLOS probabilities, path loss, and link margin. The estimated rain attenuation is employed to determine the path loss and link margin in the urban and highway scenarios. The path loss and link margin are compared with and without rain attenuation for both the urban and highway scenarios, and the optimal path difference in these scenarios is estimated. Figures 1 and 2 visualize the path attenuation under specific conditions: a rainfall rate of 0.01%, mmWave frequencies spanning from 10 GHz to 100 GHz, and path differences ranging from 100 m to 1 km in the former figure and 10 km to 100 km in the latter. Analyzing these two figures confirms that the path attenuation increases as the operating frequency and path difference increase. Figure 1: Path attenuation due to rainfall rate of 0.01% and path difference from 100 m to 1000 m.  
Figure 2: Path attenuation due to rainfall rate of 0.01% and path difference from 10 km to 100 km. Within the range of mmWave frequencies (10-100 GHz) and path differences between 100 m and 1000 m, it is evident from Figure 1 that the maximum path attenuation remains at only 7 dB. However, as the path difference extends from 1 km to 100 km, the path loss increases from 7 dB to 37 dB. Consequently, the path attenuation remains notably low for shorter path differences while significantly increasing for longer ones. This relationship underscores the direct correlation between path attenuation and path difference, highlighting that the impact of rainfall on signal propagation is more pronounced with greater path differences. Therefore, the intensity of rainfall has a notable influence on path attenuation, which in turn, impacts the overall performance of the communication system. The LOS probabilities for indoor and outdoor regions based on different probability models are shown in Figures 3 and 4, respectively. We estimated the indoor LOS probability for the ITU-R model, the WINNER-II A1 model, and our proposed model. From Figure 3, it can be noticed that the ITU-R models provide a better LOS probability with a path difference of (0-25 m) compared to the other two models. In addition, the LOS probability gradually decreases up to a 10 m path difference, then maintains a constant value or varies only slowly. Therefore, the optimal path difference for better performance in LOS propagation is estimated at 10 m in the indoor region. This optimal path difference reduces the path loss of an indoor communication system. Figure 4 shows the LOS probability variations with the path difference (0-1000 m) for the four 3 GPP outdoor models. From Figure 4, it can be noticed that the LOS probability  
Figure 4: LOS probability for the outdoor region for a path difference of 0–1000 m.  
Figure 3: LOS probability for the indoor region for a path difference of 0–25 m.  
gradually decreases as the path difference increases from 1 m to 1000 m. The LOS probability is not only affected by the path difference, as environmental conditions, antenna characteristics, and the geographical region all have impacts.