Uplink doppler metric estimation based on a downlink reference signal

A method for wireless communication at a base station, comprising:

• transmitting, to a user equipment (UE), a first repetition of a tracking reference signal in a first symbol of a subframe and a second repetition of the tracking reference signal in a second symbol of the subframe;
• receiving, from the UE, an indication of a Doppler metric for a downlink channel between the base station and the UE, the Doppler metric based at least in part on the first and second repetitions of the tracking reference signal;
• selecting a configuration for an uplink demodulation reference signal based at least in part on the Doppler metric for the downlink channel;
• and
• transmitting an indication of the configuration for the uplink demodulation reference signal to the UE.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor, memory coupled with the processor;
• and instructions stored in the memory and executable by the processor to cause the apparatus to:
• measure a first repetition and a second repetition of a tracking reference signal received over a downlink channel between the UE and a base station;
• determine a correlation in time between the first and second repetitions of the tracking reference signal based at least in part on measuring the first and second repetitions of the tracking reference signal;
• determine a Doppler metric for the downlink channel based at least in part on measuring the tracking reference signal and on the correlation in time between the first and second repetitions of the tracking reference signal;
• transmit an indication of the Doppler metric for the downlink channel to the base station;
• and
• receive, based at least in part on transmitting the indication of the Doppler metric for the downlink channel, an indication of a configuration for an uplink demodulation reference signal.

An apparatus for wireless communication at a base station, comprising:

• a processor, memory coupled with the processor;
• and instructions stored in the memory and executable by the processor to cause the apparatus to:
• transmit, to a user equipment (UE), a first repetition of a tracking reference signal in a first symbol of a subframe and a second repetition of the tracking reference signal in a second symbol of the subframe;
• receive, from the UE, an indication of a Doppler metric for a downlink channel between the base station and the UE, the Doppler metric based at least in part on the first and second repetitions of the tracking reference signal;
• select a configuration for an uplink demodulation reference signal based at least in part on the Doppler metric for the downlink channel;
• and
• transmit an indication of the configuration for the uplink demodulation reference signal to the UE.