Beamspace maximum likelihood algorithm based on sum and difference beams for elevation estimation

Beamspace super-resolution methods for elevation estimation in multipath environment has attracted significant attention, especially beamspace maximum likelihood (BML) algorithm. However, the difference beam is rarely used in super-resolution methods, especially in low elevation estimation. The target airspace information in the difference beam is different from the target airspace information in the sum beam. And the use of difference beams will not significantly increase the complexity of the system and algorithms. Thus, this paper applies the difference beam to the beamformer to improve the elevation estimation performance of BML algorithm. And the direction and number of beams can be adjusted according to the actual needs. The theoretical target elevation angle root mean square error (RMSE) and the computational complexity of proposed algorithms are analyzed. Finally, our computer simulations and real data processing results demonstrate the effectiveness of the proposed algorithms.