Null-Steering Performance Degradation Due to Sensor Element Position Measurement Errors.

摘要

This paper examines the performance degradation of a linearly-constrained, optimum beamformer designed to steer nulls in the direction of interfering sources. The proposed beamformer is optimum in the sense that beamformer response to ambient noise uncorrelated with the signals and interferers is minimized. Beampattern nulls and the maximum response axis (MRA) are steered in any desired direction by applying the method of Lagrange multipliers to constrain the beamformer directional response and then the output power is minimized subject to these constraints. The receiving array is allowed arbitrary spatial configurations in the analytical treatment, but specific, near-planar configurations are used in computer simulations of the algorithm. The measure of performance used is the ratio of output power due to sources in the directions of steered nulls to the power due to a source in the direction of the steered MRA. This ratio is examined as the error in measurement of sensor locations increases. An upper bound on this ratio is derived in terms of the maximum sensor element position measurement error. Computer simulations indicate that the upper bound derived is conservative. (Author)