Cross-Band Optical/RF Networks With Zero-Energy Devices

In this work, we study a cross-band network which simultaneously utilizes optical wireless (OW) and radio frequency (RF). OW is used for the downlink scenario to simultaneously transmit information and transfer power to the devices, while the RF band is used for both the downlink scenario, i.e., energy transferring, and the uplink scenario, i.e., transmitting information from the devices to the access point (AP). The devices harvest energy from both bands to transmit their data at the maximum possible rate without exceeding the harvested energy. A non-convex rate maximization problem is formulated which, with appropriate transformations, becomes an equivalent convex problem. By solving this problem, the optimal transmit power of the AP in both bands, the optimal durations of the energy harvesting and random access phases, the channel access probability, and the rates of each device are determined.