Virtual Multiantenna Array for Estimating the DOA of a Transmitter in UAV-assisted Networks

摘要

A method is proposed to estimate the direction of a ground radio-frequency (RF) transmitter by using an Unmanned Aerial Vehicle (UAV) equipped with a single antenna, which is critical when considering the form factor and computational capabilities of a UAV. By considering the received signal at several locations along its trajectory, the UAV receiver implicitly creates a virtual multi-antenna array (VMA), which can estimate the direction-of-arrival (DOA) of the transmitter. The major difficulty is the Local Oscillator (LO) frequency offset that occurs between the transmitter and the UAV receiver, which adds a cumulative phase offset to the received signal at each antenna of the virtual array. Oscillators of inferior qualities will undergo severe phase and frequency drifts over time, and these LO offsets must be estimated and compensated during DOA estimation. To overcome this difficulty, we proposed two approaches by estimating the LO frequency offset jointly with the direction of the transmitter. Then we extend the Multiple Signal Classification (MUSIC) algorithm to perform multidimensional estimation (including azimuth and elevation). In this paper, the proposed VMA method is simulated and tested by considering different virtual array geometries and various LO qualities. Simulation results prove the feasibility of our proposed method, and the median estimation error for azimuth and elevation are below 9^◦ and 12^◦ on average, even with low-quality oscillators.