Method and apparatus for enabling uplink MIMO

1. A user equipment (UE) comprising:

a transceiver configured to receive, from a base station (BS), an uplink (UL) grant for an UL transmission and a higher layer signal including an indication of one of two transmission schemes; and

a processor operably connected to the transceiver, the processor configured to:

decode, for a first transmission scheme of the transmission schemes, a precoding information field in downlink control information (DCI) associated with the UL grant, wherein the precoding information field includes at least one precoding matrix indicator (PMI) corresponding to a plurality of precoders; and

determine, for the first transmission scheme, a precoder of the plurality of precoders for the UL transmission based on the PMI in the DCI,

wherein the transceiver is further configured to:

precode a data stream according to the determined precoder indicated by the precoding information field; and

transmit, to the BS, the precoded data stream on an UL channel.

2. The UE of claim 1 , wherein a number of PMIs included in the precoding information field is at least equal to a number of the precoders and at least one of the number of PMIs is associated with a subband that corresponds to at least one resource block (RB).

3. The UE of claim 2 , wherein the number of PMIs is fixed and a number of RBs per subband depends on allocated RBs as indicated in an UL resource allocation (RA) field of the DCI.

4. The UE of claim 3 , wherein the number of PMIs is at least two and the DCI further includes a subband indicator field for one of the PMIs.

5. The UE of claim 2 , wherein at least one PMI that is associated with a subband is transmitted separately from the DCI that includes a resource allocation (RA) field.

6. The UE of claim 1 , wherein the precoding information field includes a single PMI and the single PMI indicates a group including the plurality of precoders.

7. The UE of claim 6 , wherein the processor is further configured to either select a precoder from the group or derive a precoder from a combination of at least two precoders in the group for the granted UL transmission.

8. A base station (BS) comprising:

a processor configured to:

generate a precoding information field in downlink control information (DCI); and

generate an uplink (UL) grant for an UL transmission and a higher layer signal including an indication of one of two transmission schemes; and

a transceiver operably connected to the processor, the transceiver configured to:

transmit, to a user equipment (UE), the UL grant and the higher layer signal including the indication of one of two transmission schemes via a downlink (DL) channel, wherein the DCI is associated with the UL grant, wherein, for a first transmission scheme of the two transmission schemes, the precoding information field includes at least one precoding matrix indicator (PMI) corresponding to a plurality of precoders, and wherein a precoder of the plurality of precoders, for the UL transmission based on the PMI in the DCI, is determined in accordance with the first transmission scheme; and

receive, from the UE, precoded data stream on an UL channel.

9. The BS of claim 8 , wherein a number of PMIs included in the precoding information field is at least equal to a number of the precoders and at least one of the number of PMIs is associated with a subband that corresponds to at least one resource block (RB).

10. The BS of claim 9 , wherein the number of PMIs is fixed and a number of RBs per subband depends on allocated RBs as indicated in an UL resource allocation (RA) field of the DCI.

11. The BS of claim 10 , wherein the number of PMIs is at least two and the DCI further includes a subband indicator field for one of the PMIs.

12. The BS of claim 9 , wherein at least one PMI that is associated with a subband is transmitted separately from the DCI that includes a resource allocation (RA) field.

13. The BS of claim 8 , wherein the precoding information field includes a single PMI and the single PMI indicates a group including the plurality of precoders.

14. A method for operating a user equipment (UE), the method comprising:

receiving, from a base station (BS), an uplink (UL) grant for an UL transmission and a higher layer signal including an indication of one of two transmission schemes;

decoding, for a first transmission scheme of the transmission schemes, a precoding information field in downlink control information (DCI) associated with the UL grant, wherein the precoding information field includes at least one precoding matrix indictor (PMI) corresponding to a plurality of precoders;

determining, for the first transmission scheme, a precoder of the plurality of precoders for the UL transmission based on the PMI in the DCI;

precoding a data stream according to the determined precoder indicated by the precoding information field; and

transmitting, to the BS, the precoded data stream on an UL channel.

15. The method of claim 14 , wherein a number of PMIs included in the precoding information field is at least equal to a number of the precoders and at least one of the number of PMIs is associated with a subband that corresponds to at least one resource block (RB).

16. The method of claim 15 , wherein the number of PMIs is fixed and a number of RBs per subband depends on allocated RBs as indicated in an UL resource allocation (RA) field of the DCI.

17. The method of claim 16 , wherein the number of PMIs is at least two and the DCI further includes a subband indicator field for one of the PMIs.

18. The method of claim 15 , wherein at least one PMI that is associated with a subband is transmitted separately from the DCI that includes a resource allocation (RA) field.

19. The method of claim 14 , wherein precoding information field includes a single PMI and the single PMI indicates a group including the plurality of precoders.

20. The method of claim 19 , wherein the UE either selects a precoder from the group or derives a precoder from a combination of at least two precoders in the group for the granted UL transmission.