# Vegetation Loss Measurements for Single Alley Trees in Millimeter-Wave Bands
## 6 Conclusions  
The experimental data shown in this article indicate a high attenuation rate at short distances into woods and the sharp transition that exists between the lower and higher attenuation regions. This transition occurs after the second tree in the present measurement campaign. Each tree's corona is characterized by quite a large value of density, understood as the number of scatterers per unit volume. Certainly, measured attenuation exceeds the values of the single-tree attenuation model. This is why this phenomenon requires deeper investigation. The enhanced model would replace the simplified forest half-space by a two-layer slab model on a ground plane with well-defined absorption and scattering parameters.  
The major observation during the present campaign is that the measured woodland is not fully statistically homogeneous. There are irregularities in the canopy of trees and free space between trees. The LIDAR method seems promising when it comes to an accurate description of a single tree's physical structure. Using this method, one can quantify the wood area and acquire proper tree dimensions and the volume occupied by leaves.  
In this article, the model for scattering through foliage is described. However, the model is quite complicated, especially when the correct input parameters are needed. Some research and development steps were carried out to improve this approach. Furthermore, as a future step, to simplify this task, the idea of obtaining branches and leaves' parameters may be developed using a drone equipped with a LIDAR scanner. Drone flight around the obstacle on the radio-wave path can quantify a sufficient number of cloud points. Based on this, important tree parameters can be extracted and recalculated. Thismethod is capable of introducing a modern digital combined solution to the mmWave measurement methodology.  
Conceptualization, K.C., M.N. and A.K.; methodology, K.C. and M.N.; software, M.N.; validation, K.C. and M.N.; formal analysis, K.C. and M.N.; investigation, K.C. and M.N.; writing--original draft preparation, review, and editing, K.C., M.N. and A.K.; visualization, M.N.; supervision, K.C.; project administration, K.C. and A.K.; funding acquisition, A.K. All authors have read and agreed to the published version of the manuscript.  
The presented work was supported by project no. 0312/SBAD/8163.  
Not applicable.  
Data Availability Statement: Data are contained within the article.  
The authors declare no conflicts of interest. Author [PERSON] was employed by the company Tietocury. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} CW & Continuous wave \\ FWA & Fixed wireless access \\ ITU & International telecommunication union \\ LIDAR & Light detection and ranging \\ LMedS & Least median of squares \\ LoRa & Long range \\ MA & Maximum attenuation \\ MED & Maximum exponential decay \\ mmWave & Millimeter wave \\ PAI & Plant area index \\ RBW & Resolution bandwidth \\ RMSE & Root mean square error \\ RTE & Radiative transfer equation \\ UAV & Unmanned aerial vehicle \\ UE & User equipment \\ \end{tabular}