Performance Evaluation of UAV Aided Overlay Cognitive STBC-NOMA System

This paper investigates the performance of un-manned aerial vehicle (UAV) aided overlay cognitive network (OCN) with space time block code aided non-orthogonal multiple access (STBC-NOMA) technique. In the network, the UAV acts as a secondary transmitter which simultaneously transmit its information along with the decoded information from the primary transmitter to the respective users. The closed-form expressions of outage probability (OP) and ergodic rate (ER) of users are obtained. It is observed that the performance of OCN with STBC-NOMA scheme is superior to OCN with NOMA scheme in terms of OP and ER. Monte Carlo simulations are provided for verification of analytical expressions. Further, the optimal horizontal coordinates of the UAV are obtained using the exhaustive search.