Channel Gain Lower Bound for IRS-Assisted UAV-Aided Communications

The Multiple-Input-Multiple-Output (MIMO) capabilities of an Intelligent Reflective Surface (IRS) combined with the inherent versatility of an Unmanned Aerial Vehicle (UAV) can significantly enhance the communication quality between a Ground User (GU) and a Base Station (BS). This work proposes a composite channel gain expression for performance analysis in IRS-assisted UAV-aided networks under Rician fading conditions. Differently from the present literature, the proposed formulation takes into account wave interference among surface elements and with the receiver. Moreover, Orthogonal Frequency Multiple Access (OFDMA) is employed to cope with spatial-and frequency-selective fading, enabling direct application in multi-user multi-drone scenarios. Numerical results demonstrate that the proposed model provides an underestimate, as expected from theoretical analysis, from which a lower bound for the data rate can be obtained, to be practically employed for system design and assessment.