Joint Blocklength and Trajectory Optimizations for URLLC-Enabled UAV Relay System

In this letter, we investigate the joint design of blocklength resource allocation and unmanned aerial vehicle (UAV) trajectory for the ultra-reliable and low-latency communication (URLLC)-enabled UAV relay wireless communication system utilizing the decode-and-forward (DF) protocol, where a UAV acts as a relay to assist the communication from a ground base station to multiple ground users. Unlike the existing works that mainly focus on the UAV position and decoding errors, this letter aims to maximize the end-to-end information rate by optimizing the blocklengths and UAV trajectory, subject to the requirements of UAV flight limitations and finite blocklengths. Although the formulated problem is an intractable non-convex problem with mixed integer programming, by analyzing the structure of the problem, we develop an effective solution algorithm combining successive convex approximation (SCA), relaxation, and integerization techniques. Simulation results verify the effectiveness of the proposed algorithm.