Direction-of-Arrival Estimation With Virtual Antenna Array: Observability Analysis, Local Oscillator Frequency Offset Compensation, and Experimental Results

Abstract

Estimating the direction-of-arrival (DoA) of radio frequency sources is essential in many wireless applications. Traditional DoA estimation based on bearing measurements requires multiantenna arrays, which is not suitable for portable electronics for its large form factor. In this article, we improved a novelty single-antenna-based DoA estimation technique, called virtual multiantenna arrays. While the device is moving and continuously receiving signals, the DoA can be estimated by measuring the intercepted signals at several positions along the receiver's trajectory. Previous virtual array technology left two unsolved problems. Some receiver movements are not able to estimate the DoA, without a theoretical basis to screen feasible trajectories; the virtual array requires precise, relative coordinates of the receiver, which is challenging in reality. This article investigates the feasibility of the virtual array and improves its robustness by addressing these two unsolved problems. A theoretical foundation for feasible receiver trajectory determination is provided; the receiver has to move with accelerations to make the DoA observable. Also, we prove the nature that the DoA could be estimated by measuring the accelerations only, where precise receiver position is not mandatory. These results indicate that the virtual array is feasible with simple receiver movements and low-cost commercial equipment, thus significantly reducing system complexity and cost. Simulations are conducted to validate our theoretical predictions. The proof of concept implemented on a software-defined radio testbed also proves the validity and suitability of the improved DoA estimation technology in applications with form-factor constraints.