Symmetric sum coarray based co-prime MIMO configuration for direction of arrival estimation

This paper proposes a symmetric co-prime multiple input multiple output (MIMO) configuration for direction of arrival (DOA) estimation, where the transmitter has 4M-1 sensors with spacing of N units and the receiver has 2N-1 sensors with spacing of M units. By separating the transmitter and receiver into two subarrays respectively, the symmetric sum coarray (SSC) exploits four sum coarrays based on the received signal model, and the difference coarray of SSC (DSSC) is developed by vectorizing the sample covariance matrix. The analytical expressions for the coarray aperture, the maximum consecutive integers and the attainable number of unique lags are derived carefully. Compared with the existing configurations, SSC and DSSC can obtain larger number of degrees of freedom (DOFs). Then, the DOA estimation of mutually coherent and uncorrelated targets is employed for illustration. Simulation results demonstrate the effectiveness of proposed configuration.