Channel estimation and demodulation procedure for non-linear multi-user multiple-input multiple-output precoding

An apparatus for wireless communications at a first 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:
• receive, from a base station, control signaling indicating that a first linear precoding vector is applied to a first combination of data sets and that a second linear precoding vector is applied to a second combination of data sets, wherein the first combination is of a first data set for the first UE and a second data set for a second UE, and the second combination is also of the first data set for the first UE and the second data set for the second UE but is different from the first combination;
• receive, from the base station via a first comb associated with a first port and a second port, a first demodulation reference signal associated with the first port and a second demodulation reference signal associated with the second port;
• and
• receive, from the base station via a second comb associated with at least a third demodulation reference signal associated with a third port, a message comprising:
• a first indication of a first set of coefficients indicative of the first combination of data sets;
• and
• a second indication of a second set of coefficients indicative of the second combination of data sets.

A method of wireless communications at a base station, comprising:

• associating a first port with a plurality of antenna elements of an antenna array, the first port based at least in part on a first linear precoding vector and having a first phase;
• associating a second port with the plurality of antenna elements of the antenna array, the second port based at least in part on a second linear precoding vector and a phase shift such that the second port has a second phase that is coherent with the first phase;
• transmitting, to a first user equipment (UE) and a second UE, control signaling indicating that the first linear precoding vector is applied to a first combination of data sets and that the second linear precoding vector is applied to a second combination of data sets, wherein the first combination is of a first data set for the first UE and a second data set for the second UE, and the second combination is also of the first data set for the first UE and the second data set for the second UE but is different from the first combination;
• transmitting a first demodulation reference signal associated with the first port;
• transmitting a second demodulation reference signal associated with the second port;
• and
• transmitting a third demodulation reference signal associated with a third port at the base station, wherein the third demodulation reference signal includes information for extracting the first data set for the first UE and the second data set for the second UE.

A method of wireless communications at a first user equipment (UE), comprising:

• receiving, from a base station, control signaling indicating that a first linear precoding vector is applied to a first combination of data sets and that a second linear precoding vector is applied to a second combination of data sets, wherein the first combination is of a first data set for the first UE and a second data set for a second UE, and the second combination is also of the first data set for the first UE and the second data set for the second UE but is different from the first combination;
• receiving, from the base station via a first comb associated with a first port and a second port, a first demodulation reference signal associated with the first port and a second demodulation reference signal associated with the second port;
• and
• receiving, from the base station via a second comb associated with at least a third demodulation reference signal associated with a third port, a message comprising:
• a first indication of a first set of coefficients indicative of the first combination of data sets;
• and
• a second indication of a second set of coefficients indicative of the second combination of data sets.