Uplink multiple-input multiple-output with different antenna groups

1 . A method of wireless communication performed by a user equipment (UE), the method comprising:

receiving, from a base station, an indication of at least one active antenna port group of a plurality of antenna port groups, wherein the plurality of antenna port groups comprises a first antenna port group and a second antenna port group, wherein the indication comprising a first indication indicates that the first antenna port group is the at least one active antenna port group, and wherein the indication comprising a second indication indicates that the second antenna port group is the at least one active antenna port group; and

mapping one or more layers of an uplink message to the at least one active antenna port group based at least in part on the indication of the at least one active antenna port group.

2 . The method of claim 1 , wherein receiving the indication comprises receiving a respective transmit precoding matrix indicator (TPMI) for each active antenna port group of the at least one active antenna port group.

3 . The method of claim 2 , wherein receiving the respective TPMI for each active antenna port group comprises:

receiving the respective TPMI for each active antenna port group in a downlink control information message.

4 . The method of claim 1 , further comprising:

receiving, from the base station, an indication of a quantity of the one or more layers of the uplink message, wherein mapping the one or more layers of the uplink message is based at least in part on the indication of the quantity of the one or more layers of the uplink message.

5 . The method of claim 1 , further comprising:

transmitting, to the base station, a capability report indicating one or more antennas in each of the plurality of antenna port groups, wherein receiving the indication of the at least one active antenna port group is based at least in part on transmitting the capability report.

6 . The method of claim 5 , further comprising:

transmitting, in the capability report, an indication of whether the UE is qualified of performing coherent transmissions utilizing one or more sets of antennas in each antenna port group.

7 . The method of claim 1 , wherein the mapping of the one or more layers of the uplink message to the at least one active antenna port group is defined at the UE.

8 . The method of claim 7 , wherein a quantity of the one or more layers of the uplink message, L, is greater than or equal to a quantity of the at least one active antenna port group, N, and the mapping is based at least in part on a mapping rule that maps a layer with index i to an active antenna port group with index i mod N.

9 . The method of claim 7 , wherein a quantity of the one or more layers of the uplink message, L, is less than a quantity of the at least one active antenna port group, N, and the mapping is based at least in part on a mapping rule that maps an active antenna port group with index n to a layer with index n mod L.

10 . The method of claim 1 , further comprising:

receiving an indication of the mapping of the one or more layers of the uplink message to the at least one active antenna port group.

11 . The method of claim 10 , wherein receiving the indication of the mapping comprises:

receiving the indication of the mapping in a downlink control information message, a radio resource control message, or a medium access control control element.

12 . The method of claim 1 , wherein receiving the indication of the at least one active antenna port group of the plurality of antenna port groups comprises:

receiving the indication of the at least one active antenna port group of the plurality of antenna port groups in a downlink control information message, a radio resource control message, or a medium access control control element.

13 . The method of claim 1 , wherein the indication of the at least one active antenna port group of the plurality of antenna port groups comprises a bitmap indicating the at least one active antenna port group of the plurality of antenna port groups.

14 . The method of claim 1 , wherein the UE comprises a virtual UE, and the plurality of antenna port groups at the UE comprises antenna port groups at one or more physical UEs.

15 . The method of claim 1 , further comprising:

transmitting, to the base station, the uplink message.

16 . The method of claim 1 , wherein the indication comprises a transmit precoding matrix indicator (TPMI).

17 . The method of claim 1 , wherein the indication comprises a respective transmit precoding matrix indicator (TPMI) for each active antenna port group of the at least one active antenna port group.

18 . A method of wireless communication performed by a base station, the method comprising:

transmitting, to a user equipment (UE), an indication of at least one active antenna port group of a plurality of antenna port groups, wherein the plurality of antenna port groups comprises a first antenna port group and a second antenna port group, wherein the indication comprising a first indication indicates that the first antenna port group is the at least one active antenna port group, and wherein the indication comprising a second indication indicates that the second antenna port group is the at least one active antenna port group; and

receiving, from the UE, one or more layers of an uplink message mapped to the at least one active antenna port group based at least in part on the indication of the at least one active antenna port group.

19 . The method of claim 18 , wherein transmitting the indication comprises transmitting a respective transmit precoding matrix indicator (TPMI) for each active antenna port group of the at least one active antenna port group.

20 . The method of claim 19 , wherein transmitting the respective TPMI for each active antenna port group comprises:

transmitting the respective TPMI for each active antenna port group in a downlink control information message.

21 . The method of claim 18 , further comprising:

transmitting, to the UE, an indication of a quantity of the one or more layers of the uplink message, wherein receiving the one or more layers of the uplink message is based at least in part on the indication of the quantity of the one or more layers of the uplink message.

22 . The method of claim 18 , further comprising:

receiving, from the UE, a capability report indicating one or more antennas in each of the plurality of antenna port groups, wherein transmitting the indication of the at least one active antenna port group is based at least in part on receiving the capability report.

23 . The method of claim 22 , further comprising:

receiving, in the capability report, an indication of whether the UE is qualified of performing coherent transmissions utilizing one or more sets of antennas in each antenna port group.

24 . The method of claim 18 , further comprising:

transmitting an indication of a mapping of the one or more layers of the uplink message to the at least one active antenna port group.

25 . The method of claim 24 , wherein transmitting the indication of the mapping comprises:

transmitting the indication of the mapping in a downlink control information message, a radio resource control message, or a medium access control control element.

26 . The method of claim 18 , wherein transmitting the indication of the at least one active antenna port group of the plurality of antenna port groups comprises:

transmitting the indication of the at least one active antenna port group of the plurality of antenna port groups in a downlink control information message, a radio resource control message, or a medium access control control element.

27 . The method of claim 18 , wherein the indication of the at least one active antenna port group of the plurality of antenna port groups comprises a bitmap indicating the at least one active antenna port group of the plurality of antenna port groups.

28 . The method of claim 18 , wherein the UE comprises a virtual UE, and the plurality of antenna port groups at the UE comprises antenna port groups at one or more physical UEs.

29 . An apparatus for wireless communication at a user equipment (UE), the apparatus 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, an indication of at least one active antenna port group of a plurality of antenna port groups, wherein the plurality of antenna port groups comprises a first antenna port group and a second antenna port group, wherein the indication comprising a first indication indicates that the first antenna port group is the at least one active antenna port group, and wherein the indication comprising a second indication indicates that the second antenna port group is the at least one active antenna port group; and

map one or more layers of an uplink message to the at least one active antenna port group based at least in part on the indication of the at least one active antenna port group.

30 . The apparatus of claim 29 , wherein, to receive the indication, the instructions are further executable by the processor to cause the apparatus to:

receive a respective transmit precoding matrix indicator (TPMI) for each active antenna port group of the at least one active antenna port group.

31 . The apparatus of claim 29 , wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to the base station, a capability report indicating one or more antennas in each of the plurality of antenna port groups, wherein receiving the indication of the at least one active antenna port group is based at least in part on transmitting the capability report.

32 . The apparatus of claim 29 , wherein the instructions are further executable by the processor to cause the apparatus to:

transmit, to the base station, the uplink message.

33 . The apparatus of claim 29 , wherein the indication comprises a transmit precoding matrix indicator (TPMI).

34 . The apparatus of claim 29 , wherein the indication comprises a respective transmit precoding matrix indicator (TPMI) for each active antenna port group of the at least one active antenna port group.

35 . An apparatus for wireless communication at a base station, the apparatus 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), an indication of at least one active antenna port group of a plurality of antenna port groups the plurality of antenna port groups comprises a first antenna port group and a second port antenna port group, wherein the indication comprising a first indication indicates that the first antenna port group is the at least one active antenna port group, and wherein the indication comprising a second indication indicates that the second antenna port group is the at least one active antenna port group; and

receive, from the UE, one or more layers of an uplink message mapped to the at least one active antenna port group based at least in part on the indication of the at least one active antenna port group.

36 . The apparatus of claim 35 , wherein, to transmit the indication, the instructions are further executable by the processor to cause the apparatus to:

transmit a respective transmit precoding matrix indicator (TPMI) for each active antenna port group of the at least one active antenna port group.