A Novel Cellular User Offloading via UAV-Borne IRS

Unmanned Aerial Vehicles (UAVs) can be leveraged to perform cellular user offloading in dynamic hotspot scenarios and enable the unserved users of overloaded gNodeB (gNB) use the unutilized bandwidth of a neighbouring underloaded gNB. To reach the blocked users and to minimize the co-channel interference between offloaded users and other users, we propose using UAVs mounted with two Intelligent Reflecting Surface (IRS) panels. We formulate the problem to minimize the total Service Level Agreement (SLA) violations cost by jointly optimizing the location of the UAV, user association, phase shifts of the IRS elements, transmit power allocation, and bandwidth allocation. Further, we propose an efficient heuristic solution to the formulated problem and show its effectiveness using numerical simulations. Through our simulations, we show that the total SLA violation cost decreases by up to 17.18% and spectral efficiency increases by up to 6.66% by using 400 elements in each IRS.