## 6 Conclusions  
Research on WPT is attracting attention to miniaturizing EVs' batteries and increasing the charging range. Despite the most studied methods, magnetic induction and magnetic resonance using coils can transmit power only up to several meters; thus, the existing road infrastructure needs to be changed to use these methods for charging EVs. On the other hand, using microwaves and lasers, which have been used to charge unmanned aerial vehicles and satellites at a distance of several kilometers or more, is relatively easy desiring no change in road infrastructure. Using microwaves for charging is restricted by many  
Figure 16: Results of power transmission path establishment. \begin{table}
\begin{tabular}{l l l l l} \hline \hline  & & \multicolumn{4}{c}{**PRX-PTX Pairing Sequences**} \\  & & **First Round** & **Second Round** & **Third Round** \\ \hline \multirow{4}{*}{PRX} & R1 & 231.75 kW, 200 kW & 231.75 kW, 200 kW & 231.75 kW, 200 kW \\  & R2 & - & 318.1 kW, 300 kW & 318.1 kW, 300 kW \\  & R3 & - & - & 297.9 kW, 150 kW \\ \hline \multirow{4}{*}{PTX} & T1 & - & - & (173, 63), 300 kW \\  & T2 & (154, 13), 250 kW & (154, 13), 250 kW & (154, 13), 250 kW \\  & T3 & - & (150, 326), 200 kW & (150, 326), 200 kW \\  & T4 & - & (162, 279), 150 kW & (162, 279), 150 kW \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Results of WPC using the best PTE-based PTX selection algorithm. limitations, such as radiation, low rate of charging, radio wave interference, etc. But using a laser beam involves no interference phenomenon and power can be received from several charging units simultaneously. This paper discussed a method for selecting the optimal PTX for a PRX to fulfill its MPQ in an environment with multiple PTXs and PRXs, such as an EV. We modeled the MDP by a PRX with a PV array depending on the geometric relationship between the PTX and PRX. The simulation environment contains three PRX and four PTX where the communication occurs using a DS-OCDMA system. Three different schemes are tested wherein the PTX is selected based on the highest PTE power, least PTE power, and the best PTE power to meet the energy requirement of a PRX. It was verified that optimal PTXs are allocated for power transmission to PRXs in which three PRXs with different MPQs sequentially send power transmission requests to four PTXs with different MTPs. The MPQ of each PRX is satisfied by applying the algorithm to select the PTX according to the alignment and characteristics of the PTXs and PRXs. Results indicate that the third scheme where the selection of the PTX is based on the best PTE fulfills the PTE requirements of all the PTXs. This study can be extended to rearrange the PV arrays mounted on the PRX to enhance the MDP and the PTE by optimizing the power distribution of the PV array. Furthermore, considering that the charging time differs depending on the residual power of the battery embedded in an EV, a PTX can continue to transmit power to another PRX after completing the transmission of power to the first PRX, depending on the waiting time at a red traffic light. Given the importance of an algorithm for selecting the optimal PTX in an environment where multiple PTXs can transmit power to a PRX in need of power supply or several PTXs can transmit the required power simultaneously, additional research is required to develop algorithms for selecting PTXs in different circumstances. For applications in the real world, the method must be further enhanced to ensure safety for moving EVs. Conceptualization, G.K. and J.E. ; Data curation, G.K.; Formal analysis, I.A. ; Funding acquisition, Y.P. ; Investigation, J.E. ; Methodology, G.K.; Project administration, Y.P. ; Resources, G.K.; Software, I.A. ; Supervision, Y.P. ; Validation, G.K., I.A., and J.E. ; Visualization, I.A. ; Writing--original draft, G.K.; Writing--review & editing, I.A. All authors have read and agreed to the published version of the manuscript.