Microwave power and data transmission scheduling for IEEE 802.11-based wireless network with enormous numbers of sensors

In this paper, microwave power and sensing data transmission scheduling for machine-to-machine (M2M) wireless networks comprising enormous numbers of sensors is discussed. Due to the large numbers involved, the sensors are required to be battery-less so that they can be maintenance-free. When microwave power and sensing data are simultaneously transmitted, they interfere with each other at the receiver. As a result, separate timing schedules are needed for power and data transmissions in these networks. In addition, we discuss the number of frames successfully received and the maximum number of sensing data frames that can be collected. If the power transmission duty ratio is too low, the sensors cannot get adequate energy, resulting in a decrease in the number of sensors that try to transmit sensing data. On the other hand, if the power transmission duty ratio is too high, it is difficult for the sensors to transmit all their sensing data in the time available for data transmission. Hence, the power and data transmission duty ratios have to be determined appropriately. We also clarify characteristics associated with the number of successfully received frames using computer simulations.