A study of nested array : from concept to applications
Date of Issue2017-05-19
School of Electrical and Electronic Engineering
With the development of technology, wire communication has gradually been replaced by wireless communication. However, in the actual wireless communication, in order to complete some specific tasks and improve working performance, high antenna directivity and degree of freedom are required. Thus, antenna arrays were introduced to improve directivity and degree of free. To obtain a maximum spatial resolution and degree of freedom (DOF), nonuniform linear arrays have attracted more attention than uniform linear arrays. Based on these requirements, a new array geometry called nested array which is capable of significantly increasing the degrees of freedom of linear arrays is proposed.  Therefore, many array signal processing algorithms, such as beamforming, direction of arrival estimation could be performed based on the virtual array with a better spatial resolution and a higher DOF capacity. This project is to explore nested array concept and relevant applications based on realistic computer simulation using MATLAB software. For the first part, the concept of nested linear array is introduced. The advantages of nested linear array are verified compared with uniform linear array. Specifically, a comparison between nested array and uniform linear array based on degree of freedom and direction of arrival estimation is conducted. The MUSIC and Spatial Smoothing algorithms are applied to nested array DOA estimation. The resultant direction of arrival estimation is then compared to reveal the better performance of nested linear array by using MATLAB. Furthermore, the parameters influencing DOA estimation accuracy are also discussed. For the second part, the implementation of nested linear array beamforming is conducted. Specifically, the adaptive beamformer adopted for the nested array called Minimum Variance Distortionless Response (MVDR) beamformer is introduced. The beam pattern of MVDR beamformer is plotted to examine the performance of nested array. Besides, the nested array beamformer is also compared with the conventional uniform linear array MVDR beamformer to prove the enhancement of degree of freedom.
Final Year Project (FYP)
Nanyang Technological University