## 2 Background and Related Work
The American National Standard Institute (ANSI) for Safe Use of Lasers (ANSI Z136.1) provides guidelines for preventing beam and electrical hazards while working with laser systems [22]. HILPB can transmit power from several tens of kilometers away as long as EVs have devices, such as solar panels that can receive laser power beams, so there is no need to change infrastructure, such as existing roads. When stopping at a crossroad or crosswalk to wait for a signal, if the HILPB WPT device mounted on a traffic light provides instantaneoushigh power, it is possible to continuously charge even with a small battery. In this method, the received power is determined according to the PTX's distance, incidence angle, the solar panel area, and the power conversion efficiency of PRX. HILPB is a characteristic of a laser and solar panel so that multiple PTXs can transmit power to a single PRX, such as a PV array. Since lasers do not interfere with each other, there is not interference even if multiple PTXs are concentrated. Fast wireless charging of an EV requires simultaneous transmission of concentrated power from multiple PTXs. In coil-based magnetic induction and magnetic resonance technologies, multiple PRXs are often used for power transfer from one PTX. However, using multiple PTXs for power transfer to one PRX is a significant technical challenge [23; 24; 25; 26; 27]. In a multi-coil-based WPT system, the PTX and PRX coils should be aligned and many coils packed in the near field are prone to mutual interference, making it difficult to find an appropriate power transmission point. Therefore, enhancing the transmission power using multiple PTX/PRX coil pairs is a hot topic in EV research. A laser-based WPT system, on the other hand, enables simultaneous transmission of concentrated power from multiple PTXs to one PRX concerning the nature of lasers and the use of a PV array. Without any interference between laser beams, no mutual interference can occur even between multiple laser beams that are directed toward one single spot. If a PV array simultaneously receives multiple laser power beams, the sum of the delivered power of all beams is proportional to the total received power transmission without any power loss unless it exceeds the maximum power generation capacity of the PV array used. With the development of related technologies, the possibility of practical use of the HILPB system is increasing. However, the efficiency of the overall power transmission system is only about 10% to 20%, which is the biggest obstacle to the practical use of HILPB. In the case of capacitive power transfer, which is a short-range wireless charging method, the efficiency of the overall power transmission system reaches up to 90%. As the technology evolves, the possibility of the HILPB applications is becoming an increasing reality [28]. Conventionally, a WPT system based on HILPB requires the PTX to perform a series of processes to accurately position the target and the PRX equipped with a specialized reflector or concentrator [16; 29; 30]. The PTE of HILPB can be maximized only after the receiver is positioned accurately. The positioning process is erroneous and a large distance between the PTX and PRX makes the accurate positioning of the PRX even more challenging. Significant research efforts are in progress for accurate positioning of the PRX due to its importance for higher PTE. To resolve these issues, we propose selecting appropriate transmitters from several PTXs, where the PRX uses various WPC and coded laser pilots. When there are multiple PRXs and multiple PTXs in a HILPB WPT system, a laser pilot coded with direct-sequence optical code division multiple access (DS-OCDMA) is used to receive the power required by the PRX. The PRX calculates the RCPI of every received laser pilot to select the WPC with the highest power and then sends the information about the selected WPC to the PTX.