Enhance Degrees of Freedom for Coprime Array Using OptSpace Algorithm

Coprime arrays, consisting of two subarrays with a co-prime number of physical sensors, can effectively resolve the direction-of-arrival (DOA) estimation when the number of sources exceeds the sensors. However, the conventional coprime array direction of arrival estimation algorithms suffer from the “holes” problem. To address this issue, an effective method called OptSpace is adopted to fill the “holes” in the difference coarray domain of the coprime array. The OptSpace is an efficient and fast matrix completion algorithm and this characteristic can be extended to enhance the degrees of freedom in the difference coarray domain of the coprime array. After acquiring a complete matrix corresponding to full of degrees of freedom for the coprime array, the direction parameters via the Estimation of Signal Parameters via Rotational Invariance Techniques in the difference coarray domain of the coprime array can be estimated. The rotational invariance techniques can efficiently find the DOAs in the coarray domain without spectrum peak search process compared to other subspace-based algorithms. The numerical simulations are conducted to verify the effectiveness and superiority of the proposed approach compared to other methods.