Joint trajectory-resource optimization for UAV-enabled uplink communication networks with wireless backhaul.

This paper studies trajectory optimization and resource allocation for unmanned aerial vehicle (UAV) enabled uplink communication networks with wireless backhaul (WB), in which a UAV provides non-orthogonal multiple access (NOMA) based uplink relaying services for multiple mobile users with stochastic movement and forwards the decoded multi-user signals to a remote BS by means of a WB link. To assure that the UAV are able to forward the decoded multi-user signals to the remote BS, we formulate a problem of maximizing the uplink average achievable sum-rate by jointly optimizing UAV trajectory, each mobile user’s transmit power, and bandwidth allocation coefficients of both wireless access and backhaul links, subject to information-causality constraint, system available bandwidth limitation and power budget of each mobile user. The challenge lies in that the time-vary successive interference cancellation (SIC) decoding order results in a strong-coupled joint NOMA decoding order design and UAV trajectory optimization problem, which makes this problem intractable. To tackle this challenge, we firstly transform the original problem into a tractable form. Then, a penalized iteration approach is developed to handle the reformulated problem. Simulation results verify the proposed scheme can achieve higher uplink average achievable sum rate than benchmarks.