Integrated Radar and Communication in Ultra-Reliable and Low-Latency Communications-Enabled UAV Networks

In this work, we investigate a newly integrated radar and communication (IRAC) scheme that allows a UAV to transmit data to a ground user equipment (UE) under ultra-reliable and low-latency communications (URLLC) while measuring a ground target's radial velocity by leveraging the data signals. The IRAC scheme thus helps to reduce the hardware size and improve the resource efficiency of the UAV. To quickly estimate the target's radial velocity, we propose to use the auto-correlation function implemented at the radar receiver of the UAV. Nevertheless, the use of the auto-correlation function requires the UAV to generate two identical sequences. For this, the UAV copies a part of the original data sequence and adds it to the beginning of the sequence as the two training sequences. Increasing the copied part reduces the radial velocity estimation error. However, this results in longer transmission time, and the stringent latency requirement of the URLLC may not be satisfied. We investigate an optimization problem that optimizes the location of the UAV and the copied part to minimize the radial velocity estimation error while satisfying the latency requirement of the URLLC transmission. To solve the problem, we develop two algorithms, i.e., namely parametric algorithm and a generalized alternating minimization algorithm. Simulation results are provided to show the effectiveness of the proposed algorithms.