Abstract:

An improved sparse array design is proposed to address the limitations of the underdetermined direction of arrival estimation performance caused by holes and low uniform degrees of freedom in the difference co-array of the coprime array with compressed inter-element spacing.First,by analyzing the influence of the array structure on the redundancy and hole position of the difference co-array,it is concluded that adjusting the subarray position of the coprime array with compressed inter-element spacing can effectively reduce the redundancy of the difference co-array,increase the consecutive lags,and improve the uniform degree of freedom.Second,the physical array element positions are adjusted and the closed-form expression for designing sparse array physical array element positions is provided.Then,based on the array element positions,the closed-form expressions for the proposed sparse array degrees of freedom,uniform degrees of freedom,and the difference co-array hole positions are derived.Theoretical analysis shows that,compared to the coprime array with compressed inter-element spacing and the improved sparse array,the proposed array possesses higher degrees of freedom and uniform degrees of freedom with the same number of elements.Finally,simulation experiments on the direction of arrival estimation are conducted in various scenarios using the multiple signal classification algorithm based on spatial smoothing.The results show that the proposed sparse array has a better direction of arrival estimation performance under various experimental conditions,thus verifying the effectiveness of the design.

Key words: coprime array, uniform degrees of freedom, direction of arrival, multiple signal classification