US Patent 10193665 Reference signal for 3D MIMO in wireless communication systems

A user equipment device obtains a first measurement using a first CSI-RS sub-resource and a second measurement using a second CSI-RS sub-resource. The user device derives a single CSI-process based on the first and the second measurements and reports the CSI-process to a base station. The user device receives a message from the base station configuring the first and second CSI-RS sub-resources corresponding to the single CSI-process to be reported by the user device. The message from the base station comprises a configuration of the first CSI-RS sub-resource and a separate configuration of the second CSI-RS sub-resource. The configuration of each CSI-RS sub-resource comprises, for the corresponding CSI-RS sub-resource, at least a CSI-RS sub-resource index, a periodicity, and an offset. The user device may alternatively obtain measurements using any number of CSI-RS sub-resources and then derive and report a single CSI-process based on the plurality of measurements.