Flexible TDMA System for the Efficient Microwave Power Transmission to Multiple Power Receiver

Basically, wireless microwave power transfer system has very low power delivery efficiency and this efficiency gets extremely lower as the longer range and higher center frequency. Also, there is no room for the power control of the transmitter in the power supply station in order to keep the wireless power transfer efficiency. So, maximum power must be always transmitted. The time division multiple access (TMDA) system of the wireless microwave power transmission (MPT) is used for the multiple power receiver users. In this paper, an efficient wireless MPT system supporting multiple users power receiver that is a flexible TDMA is proposed based on the power pilot that is the power request signal including the power receiver ID (identification) number and power level status information. That is, this power pilot has the authorized user information and the user's power status information, which is transmitted to the power station for the request of power transmission. The power supply station receives the power pilots from all users. For the user identification of the multiple users, a CDMA system is used in this propose system. Next, the power station recognizes the users power level status and control the order of the power transmission sequence. The lowest power level user receives the wireless power in the first order for the longest time. On the contrarily, the power station transmits the wireless power to the user of the highest power state in the last for the shortest time. So, depending on the power level status of each individual user, the microwave power transmission (MPT) time is assigned and rearranged, which decides the power charge time in user power receiver side. This is a newly suggested flexible time division multiple access (TDMA) MPT system, which allocates power charging time differently to each user, depending on the power level status. This is very meaningful in that power transmission to multiple users is performed according to the power priority. Also, this technology can be extended into multi-user simultaneous transmission system and beamforming technology is also adopted to increase the power transmission efficiency. The phase locked loop (PLL) based retro-directive array (RDA) system is used to each user arrival angle and store the direction information which is used again to send the power to that user. These systems are designed and their performance is verified through the simulations to build and assess the microwave wireless power transmission system that supports multiple users.