Joint subcarrier and power allocation for Multi-UAV systems

This paper investigates subcarrier and power allocation in a multi-UAV OFDM system. The study considers a practical scenario, where certain subcarriers are unavailable for dynamic subcarrier allocation, on account of pre-allocation for burst transmissions. We first propose a novel iterative algorithm to jointly optimize subcarrier and power allocation, so as to maximize the sum rate of the uplink transmission in the multi- UAV OFDM system. The key idea behind our solution is converting the nontrivial allocation problem into a weighted mean square error (MSE) problem. By this means, the allocation problem can be solved by the alternating optimization method. Besides, aiming at a lower-complexity solution, we propose a heuristic allocation scheme, where subcarrier allocation and transmit power allocation are separately optimized. In the heuristic scheme, closed- form solution can be obtained for power allocation. Simulation results demonstrate that in the presence of stretched subcarrier resource, the proposed iterative joint optimization algorithm can significantly outperform the heuristic scheme, offering a higher sum rate.