Wireless communications systems and methods related to over-the-air uplink-downlink (UL-DL) reciprocity calibration. A central unit transmits downlink (DL) calibration reference signal (RS) and a calibration request. The central unit receives, in response to the calibration request, a first uplink (UL) calibration RS and a first DL channel estimate associated with a first transmission point (TP) and a first wireless communication device. The central unit transmits a DL coordinated multipoint (CoMP) joint transmission signal according to an uplink-downlink (UL-DL) reciprocity calibration. The UL-DL reciprocity calibration is based on at least a first UL channel estimate based on the first UL calibration RS, the first DL channel estimate, a second UL channel estimate associated with a second TP and the first wireless communication device, and a second DL channel estimate associated with the second TP and the first wireless communication device.

Aspects described herein relate to wireless communications. According to some aspects, a first base station may coordinate with a second base station to select beamforming codewords. The first base station may receive an index indicating beamforming codewords used by a second base station. The first base station may select a beamforming codeword for use in transmitting signals to a wireless device based on the beamforming codeword indicated by the second base station.

A communication apparatus comprises a generator that generates frequency resource position information corresponding to a first information which is based on the communication quality information received from user equipments, the frequency resource position information indicating validity or invalidity of the first information for each frequency resource, and a transmitter that transmits the first information, the frequency resource position information and a cell ID which the frequency resource position is applied, to another communication apparatus via a backhaul.

A wireless device may support a plurality of channel state information (CSI) processes. The wireless device may send an indication of a number of supported CSI processes to a first base station. The first base station may send an indication of a number of CSI processes supported by the wireless to a second base station. This information may be used during handover of the wireless device.

A wireless device may support a plurality of channel state information (CSI) processes. The wireless device may send an indication of a number of supported CSI processes to a first base station. The first base station may send an indication of a number of CSI processes supported by the wireless to a second base station. This information may be used during handover of the wireless device.

A wireless device may support a plurality of channel state information (CSI) processes. The wireless device may send an indication of a number of supported CSI processes to a first base station. The first base station may send an indication of a number of CSI processes supported by the wireless to a second base station. This information may be used during handover of the wireless device.

Aspects described herein relate to wireless communications. According to some aspects, a first base station may coordinate with a second base station to select beamforming codewords. The first base station may receive an index indicating beamforming codewords used by a second base station. The first base station may select a beamforming codeword for use in transmitting signals to a wireless device based on the beamforming codeword indicated by the second base station.

Wireless communications systems and methods related to over-the-air uplink-downlink (UL-DL) reciprocity calibration. A central unit transmits downlink (DL) calibration reference signal (RS) and a calibration request. The central unit receives, in response to the calibration request, a first uplink (UL) calibration RS and a first DL channel estimate associated with a first transmission point (TP) and a first wireless communication device. The central unit transmits a DL coordinated multipoint (CoMP) joint transmission signal according to an uplink-downlink (UL-DL) reciprocity calibration. The UL-DL reciprocity calibration is based on at least a first UL channel estimate based on the first UL calibration RS, the first DL channel estimate, a second UL channel estimate associated with a second TP and the first wireless communication device, and a second DL channel estimate associated with the second TP and the first wireless communication device.

According to one or more aspects, a serving base station may transmit a message to a target base station based on a handover decision for a wireless device. The message may include first measurement configuration parameters for the wireless device and/or an indication of a number of channel state information (CSI) processes supported by the wireless device. The serving base station may receive a response from the target base station indicating second measurement configuration parameters for use by the wireless device after handover. The serving base station may transmit a handover command to the wireless device including the second measurement configuration parameters.

According to one or more aspects, a wireless device may transmit a message to a serving base station comprising parameters indicating that the wireless device supports configuration of a first quantity of channel state information (CSI) processes. The serving base station may transmit a message to the wireless device comprising measurement configuration parameters for the wireless device. The serving base station may transmit an indication of the measurement configuration parameters to a target base station in response to a determination to make a handover of the wireless device.