Patent ID: 9031148
Filing Date: 2015-05-12
Classification: H04B

Abstract:
1. A method in a radio base station for transmitting a data signal to a user equipment in a radio communications network, wherein the radio base station is connected to an active antenna array of a number of active transmitting antennas and the radio base station serves the user equipment in the radio communications network, and wherein each active transmitting antenna comprises sub elements, and the method comprises: precoding a data signal to obtain a precoded data signal, said precoding performed with a precoder from a precoder codebook for azimuth beamforming; transforming the precoded data signal to obtain a transformed data signal using a transformation that imparts elevation beamforming, said elevation beamforming restricting elevation beamforming angles such that the transformed data signal is directed no higher than a top elevation angle defined below a horizontal center axis extending from the sub elements; and transmitting the transformed data signal from the sub elements mapped by the transformation.