Patent ID: 11894898
Assignee: TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 4:
5. A network node configured to compensate for phase error between antennas of a four-antenna dual-polarization antenna array of a radio of the network node, the network node comprising:
processing circuitry configured to apply N incremented phase rotations to one of the four antennas to produce N channel state information reference signal, CSI-RS, resources, N being an integer greater than 1, the N incremented phase rotations being obtained by multiplying a precoder codebook by a diagonal matrix whose diagonal elements are equal to one, except for one diagonal element corresponding to the one of the four antennas and being equal to exp(j2πn/N), where n is an integer from zero to N−1;
a radio interface in communication with the processing circuitry, the radio interface configured to:
transmit the N CSI-RS resources on 4 CSI-RS ports to a wireless device, WD, each of the N CSI-RS resources being transmitted with a different one of the incremented phase rotations; and
receive from the WD a CSI-RS resource indication, CRI, indicating a particular one of the N CSI-RS resources; and

the processing circuitry further configured to apply, in subsequent transmissions to the WD, a phase rotation to the one of the four antennas, the phase rotation corresponding to the indicated CSI-RS resource.