Resource Allocation for UAV-Enabled Integrated Sensing and Communication (ISAC) via Multi-Objective Optimization

In this paper, we consider an integrated sensing and communication (ISAC) system with wireless power transfer (WPT) where an unmanned aerial vehicle (UAV)-based radar serves a group of energy-limited communication users in addition to its sensing functionality. In this architecture, the radar senses the environment in phase 1 (namely sensing phase) and mean-while, the communications users (nodes) harvest and store the energy from the radar transmit signal. The stored energy is then used for information transmission from the nodes to UAV in phase 2, i.e., uplink phase. Performance of the radar system depends on the transmit signal as well as the receive filter; the energy of the transmit signal also affects the communication network because it serves as the source of uplink powers. Therefore, we cast a multi-objective design problem addressing performance of both radar and communication systems via optimizing radar transmit waveform, radar receive filter, time scheduling and uplink powers. We further take into account optimization of UAV trajectory for covering a given coverage area. The design problem is non-convex and hence, we devise a method based on alternating optimization followed by concepts of fractional programming as well as tricky majorization-minimization technique to tackle it. Numerical examples illustrate the effectiveness of the pro-posed method for performance improvement of the considered ISAC system.