MVDR beamforming and generalized sidelobe cancellation based on inverse updating with residual extraction

The "standard" minimum variance distortionless response (MVDR) beamforming algorithm of McWhirter and Shepherd (1989) is known to suffer from linear roundoff error buildup. An alternative has been developed by Moonen (1993) based on the so-called inverse QR-updating algorithm. It is amenable to pipelined implementation, but unlike the McWhirter and Shepherd algorithm, it is stable numerically. Here, a variant of the latter algorithm that combines (part of) the McWhirter and Shepherd procedure into the inverse QR updating scheme is discussed. This makes the derivation of the algorithm less complex compared to the original. Furthermore, by making use of a residual extraction property of the inverse updating procedure, an interesting correspondence of the new MVDR algorithm with so-called "generalized sidelobe cancellation" is explicitly revealed.