Charging Selection Policies for Framed Slotted ALOHA on Wireless Networks with Directional Energy Transfer

The framed slotted ALOHA is a suitable multiple access control (MAC) protocol for machine-type-communication devices due to (i) no initial setup overhead and (ii) low delay for small data. Directional wireless energy transfer can increase the radio frequency (RF) energy intensity in an intended direction to charge a device in a highly energy-efficient and low interference manner. However, when RF energy is transferred in a directional manner on the framed slotted ALOHA protocol, it is critical for the framed slotted ALOHA to determine which device is charged in an idle slot such that system throughput is increased as much as possible. This paper studies three charging selection policies for the framed slotted ALOHA, in which different acquisition ways of devices’ energy information are considered to select a device to be charged in an idle slot. Extensive simulation results show that the “dedicated slot based minimum residual energy first" policy outperforms the random selection policy which outperforms the “piggybacking information based minimum residual energy first" policy.