Uplink MIMO reference signals and data transmission schemes
Certain aspects of the present disclosure relate to methods and apparatus for Uplink MIMO reference signals and data transmission schemes communications systems operating according to 5G technologies. For example, one or more techniques for enabling PRG selection and conveying that selection are provided. In some cases, precoder selection techniques may be provided. Further, in some cases, techniques may be provided to distinguish OFDM and DFT-s-OFDM by using different ports.
1. A method for wireless communications by a user equipment (UE), comprising:
determining a size for one or more precoding resource block groups (PRGs) for the UE to use for transmitting one or more sounding reference signals (SRSs), wherein:
SRS transmission is allocated over a bandwidth including the one or more PRGs;
each PRG of the one or more PRGs includes one or more physical resource blocks (PRBs) associated with a common precoder for that PRG;
the size for the one or more PRGs corresponds to how many PRBs of the one or more PRBs are included within each PRG of the one or more PRGs; and
a plurality of PRGs of the one or more PRGs span the bandwidth allocated for SRS transmission;
precoding each PRG of the one or more PRGs with a different precoder used for transmitting the one or more SRSs within that PRG; and
transmitting, to a base station (BS), the one or more SRSs within the one or more PRGs in accordance with the determination.
2. The method of claim 1 , wherein the determination is based on signaling from the base station.
3. The method of claim 1 , further comprising transmitting an indication of at least one of a recommended size for the one or more PRGs or a recommended number of layers for transmitting the one or more SRSs to the base station.
4. The method of claim 3 , wherein the recommended size for the one or more PRGs or the recommended number of layers for transmitting the one or more SRSs are used for receiving one or more downlink reference signals from the BS.
5. The method of claim 1 , wherein the determination is based on a number of ports used for transmitting the one or more SRSs.
6. The method of claim 1 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if a number of layers for transmitting the one or more SRSs is below a predetermined number.
7. The method of claim 1 , wherein the determination is based on a power headroom of the UE.
8. The method of claim 7 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if the UE is transmitting at full power such that there is no UE power headroom available.
9. A method for wireless communications by a base station, comprising:
determining a size for one or more precoding resource block groups (PRGs) for a user equipment (UE) to use for transmitting one or more sounding reference signals (SRSs), wherein:
SRS transmission is allocated over a bandwidth including the one or more PRGs;
each PRG of the one or more PRGs includes one or more physical resource block (PRBs) associated with a common precoder for that PRG;
the size for the one or more PRGs corresponds to how many PRBs of the one or more PRBs are included within each PRG of the one or more PRGs;
a plurality of PRGs of the one or more PRGs span the bandwidth allocated for SRS transmission; and
each PRG of the one or more PRGs is precoded with a different precoder used for transmitting the one or more SRSs within that PRG; and
receiving the one or more SRSs transmitted from the UE within the one or more PRGs in accordance with the determination.
10. The method of claim 9 , further comprising signaling information regarding the size for the one or more PRGs to the UE.
11. The method of claim 9 , further comprising receiving, from the UE, an indication of at least one of a recommended size for the one or more PRGs or a recommended number of layers for transmitting the one or more SRSs.
12. The method of claim 11 , further comprising transmitting one or more downlink reference signals to the UE using the size for the one or more PRGs or the recommended number of layers for transmitting the one or more SRSs.
13. The method of claim 9 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if a number of layers for transmitting the one or more SRSs is below a predetermined number.
14. The method of claim 9 , wherein the determination is based on a number of ports used for transmitting the one or more SRSs.
15. The method of claim 9 , wherein the determination is based on a power headroom of the UE.
16. The method of claim 15 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if the UE is transmitting at full power such that there is no UE power headroom available.
17. The method of claim 15 , wherein the size for the one or more PRGs corresponds to a subband of a whole operating bandwidth if the UE is transmitting at less than full power such that there is UE power headroom available.
18. An apparatus for wireless communications by a user equipment (UE), comprising:
at least one processor configured to:
determine a size for one or more precoding resource block groups (PRGs) for the UE to use for transmitting one or more sounding reference signals (SRSs), wherein:
SRS transmission is allocated over a bandwidth including the one or more PRGs;
each PRG of the one or more PRGs includes one or more physical resource blocks (PRBs) associated with a common precoder for that PRG;
the size for the one or more PRGs corresponds to how many PRBs of the one or more PRBs are included within each PRG of the one or more PRGs; and
a plurality of PRGs of the one or more PRGs span the bandwidth allocated for SRS transmission;
precode each PRG of the one or more PRGs with a different precoder used for transmitting the one or more SRSs within that PRG; and
transmit, to a base station (BS), the one or more SRSs within the one or more PRGs in accordance with the determination; and
a memory coupled with the at least one processor.
19. The apparatus of claim 18 , wherein the determination is based on signaling from the BS.
20. The apparatus of claim 18 , wherein the at least one processor is further configured to transmit an indication of at least one of a recommended size for the one or more PRGs or a recommended number of layers for transmitting the one or more SRSs to the BS.
21. The apparatus of claim 20 , wherein the at least one processor is further configured to use the recommended size for the one or more PRGs or the recommended number of layers for the SRS transmission for receiving one or more downlink reference signals from the BS.
22. The apparatus of claim 20 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if a number of layers for transmitting the one or more SRSs is below a predetermined number.
23. The apparatus of claim 18 , wherein the determination is based on a number of ports used for transmitting the one or more SRSs.
24. The apparatus of claim 18 , wherein the determination is based on a power headroom of the UE.
25. The apparatus of claim 24 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if the UE is transmitting at full power such that there is no UE power headroom available.
26. An apparatus for wireless communications by a base station, comprising:
at least one processor configured to:
determine a size for one or more precoding resource block groups (PRGs) for a user equipment (UE) to use for transmitting one or more sounding reference signals (SRSs), wherein:
SRS transmission is allocated over a bandwidth including the one or more PRGs;
each PRG of the one or more PRGs includes one or more physical resource block (PRBs) associated with a common precoder for that PRG;
the size for the one or more PRGs corresponds to how many PRBs of the one or more PRBs are included within each PRG of the one or more PRGs;
a plurality of PRGs of the one or more PRGs span the bandwidth allocated for SRS transmission;
each PRG of the one or more PRGs is precoded with a different precoder used for transmitting the one or more SRSs within that PRG; and
receive the one or more SRSs transmitted from the UE within the one or more PRGs in accordance with the determination; and
a memory coupled with the at least one processor.
27. The apparatus of claim 26 , wherein the at least one processor is further configured to signal information regarding the size for the one or more PRGs to the UE.
28. The apparatus of claim 26 , wherein the at least one processor is further configured to receive, from the UE, an indication of at least one of a recommended size for the one or more PRGs or a recommended number of layers for transmitting the one or more SRSs.
29. The apparatus of claim 28 , wherein the at least one processor is further configured to transmit one or more downlink reference signals to the UE using the recommended size for the one or more PRGs or the recommended number of layers for transmitting the one or more SRSs.
30. The apparatus of claim 28 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if a number of layers for transmitting the one or more SRSs is below a predetermined number.
31. The apparatus of claim 26 , wherein the determination is based on a number of ports used for transmitting the one or more SRSs.
32. The apparatus of claim 26 , wherein the determination is based on a power headroom of the UE.
33. The apparatus of claim 32 , wherein the size for the one or more PRGs corresponds to a whole operating bandwidth if the UE is transmitting at full power such that there is no UE power headroom available.