An Off-Grid DOA Estimation Algorithm Based on Sparse Bayesian Learning
In this paper,an improved off-grid DOA estimation algorithm based on sparse Bayesian learning is pro-posed to improve the performance of DOA estimation in non-ideal direction finding environment with low SNRs and low snapshots,which is called MOGSBL algorithm.The algorithm discretizes the signal source orientation interval to obtain an orientation discrete grid.A sparse Bayesian model is established for the array received signal,and the grid node cor-rections are set as the model hyper-parameters.The expectation maximization algorithm is used to iteratively update the grid node corrections,so that the updated grid nodes are closer to the real source signal orientation.In order to test the performance of the MOGSBL algorithm,a large amount of numerical experiments are conducted,and the comparisons are made among the DOA estimation results of the MOGSBL algorithm,the RSBL algorithm,the OGSBL algorithm and the L1-SVD algorithm.At different SNRs and different amounts of snapshots,the MOGSBL algorithm can clearly distin-guish the two signal sources at close orientations,and the angular resolution is significantly higher than the RSBL algo-rithm,the OGSBL algorithm and the L1-SVD algorithm.With the increase of the SNR and the number of snapshots,the RMSE of all four algorithms gradually decreases,while the RMSE of the MOGSBL algorithm is clearly lower than the RSBL algorithm,the OGSBL algorithms and L1-SVD algorithm,and the RSBL algorithm and the OGSBL algorithm are better than the L1-SVD algorithm.The experiments also analyze the effect of the number of discrete grid nodes in the di-rection test range on DOA estimation.It is found that a fine discrete grid can improve the DOA estimation accuracy,how-ever,the computational effort of DOA estimation will increase.And at any number of grid nodes,the MOGSBL algorithm in this paper has the lowest RMSE and the shortest computation time compared with the RSBL algorithm,the OGSBL al-gorithm and the L1-SVD algorithm.
DOA estimationoff-grid modelsparse Bayesian learninggrid updateangular resolution
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