An Efficient Method to Determine the Diagonal Loading Factor for PAM Communication System

Minimum variance distortionless response (MVDR) beamformer are known to degrade due to the effects of imprecise knowledge about the steering vector and finite sample size. The diagonal loading method is a simple and efficient method that improves the robustness of beamformers. However, determining an ideal diagonal loading factor (DLF) is not a trivial problem, one that still has not been adequately addressed. Although beamformers are widely used in radar, sonar, and many other applications, in this paper, we consider only the pulse-amplitude modulation (PAM) digital communication applications. In this paper we take advantage of the binary feature in PAM digital communication system and present an effective method to determine the DLF. Since the binary feature is used, the new method does not require extra assumptions as in other methods. Numerical experiments show that the method improves the robustness of beamformers against mismatch caused by effects related to imprecise knowledge of the steering vector and finite sample size.