Precoding reference signals for uplink transmission with downlink interference information
Certain aspects of the present disclosure relate to methods and apparatus relating to precoding reference signals for uplink transmissions with downlink interference information. In certain aspects, a method, performed by a user equipment (UE) includes receiving, from a base station, one or more signals for use in estimating channel quality for a downlink between the base station and the UE. The method also includes determining a first frequency resource and a second frequency resource from a frequency band allocated for transmitting a reference signal (RS). The method further includes computing a first downlink channel quality estimate for the first frequency resource using the one or more signals, transmitting a first RS precoded using the first downlink channel quality estimate, computing a second downlink channel quality estimate for the second frequency resource using the one or more signals and transmitting a second RS precoded using the second downlink channel quality estimate.
1. A method of wireless communications for use by a user equipment (UE), comprising:
receiving, from a base station, one or more signals for use in estimating channel quality for a downlink between the base station and the UE; and
transmitting a first reference signal (RS) precoded with a first downlink channel quality estimate, wherein:
the first RS comprises the first downlink channel quality estimate,
the first downlink channel quality estimate is based on a first frequency resource of the one or more signals, and
a frequency band allocated for RS transmission includes the first frequency resource.
2. The method of claim 1 , further comprising:
transmitting a second reference signal (RS) precoded with a second downlink channel quality estimate, wherein:
the second RS comprises the second downlink channel quality estimate,
the second downlink channel quality estimate is based on a second frequency resource of the one or more signals, and
the frequency band allocated for RS transmission includes the second frequency resource.
3. The method of claim 2 , wherein the first downlink channel quality estimate comprises a first interference covariance matrix (R nn ) and the second downlink channel quality estimate comprises a second RR nn , and wherein the first RS comprises a first sounding reference signal (SRS) and the second RS comprises a second SRS.
4. The method of claim 2 , wherein the first frequency resource and the second frequency resource are determined based on a message received from the base station for triggering the UE to perform a RS transmission.
5. The method of claim 4 , wherein the message comprises downlink control information for sounding reference signal (SRS) scheduling.
6. The method of claim 4 , wherein the message identifies one of a plurality of configurations, each configuration corresponding to a different set of frequency resources.
7. The method of claim 2 , wherein the first frequency resource and the second frequency resource are determined based on a range of the frequency band allocated for RS transmission.
8. The method of claim 2 , wherein the first frequency resource and the second frequency resource are determined based on capabilities of the UE.
9. The method of claim 2 , wherein the first frequency resource and the second frequency resource are determined based on time available between events of receiving a message indicating transmission of RS, receiving the one or more signals for use in estimating the channel quality, and transmitting the first RS.
10. The method of claim 1 , wherein the frequency band allocated for RS transmission comprises resource blocks (RBs).
11. The method of claim 1 , wherein:
transmitting the first RS comprises transmitting the first RS over all frequency resources of the frequency band; and
the first frequency resource corresponds to all frequency resources of the frequency band.
12. The method of claim 1 , wherein:
transmitting the first RS comprises transmitting the first RS over all frequency resources of the frequency band at a first time; and
the first frequency resource corresponds to a first subset of the frequency resources of the frequency band.
13. The method of claim 12 , further comprising:
transmitting a second RS precoded with a second downlink channel quality estimate, wherein:
the second RS comprises the second downlink channel quality estimate,
the second downlink channel quality estimate is based on a second frequency resource of the one or more signals,
the frequency band allocated for RS transmission includes the second frequency resource,
transmitting the second RS comprises transmitting the second RS over all the frequency resources of the frequency band at a second time, and
the second frequency resource corresponds to a second subset of the frequency resources of the frequency band.
14. The method of claim 1 , wherein:
transmitting the first RS comprises transmitting the first RS over the first frequency resource; and
the first frequency resource corresponds to a first subset of the frequency resources of the frequency band.
15. The method of claim 14 , further comprising:
transmitting a second RS precoded with a second downlink channel quality estimate, wherein:
the second RS comprises the second downlink channel quality estimate,
the second downlink channel quality estimate is based on a second frequency resource of the one or more signals,
the frequency band allocated for RS transmission includes the second frequency resource,
transmitting the second RS comprises transmitting the second RS the second frequency resource, and
the second frequency resource corresponds to a second subset of the frequency resources of the frequency band.
16. A user equipment (UE), comprising:
a memory; and
a processor coupled to the memory, the processor and the memory are configured to:
receive, from a base station, one or more signals for use in estimating channel quality for a downlink between the base station and the UE; and
transmit a first reference signal (RS) precoded with a first downlink channel quality estimate, wherein:
the first RS comprises the first downlink channel quality estimate,
the first downlink channel quality estimate is based on a first frequency resource of the one or more signals, and
a frequency band allocated for RS transmission includes the first frequency resource.
17. The UE of claim 16 , wherein the memory and the processor are further configured to:
transmit a second reference signal (RS) precoded with a second downlink channel quality estimate, wherein:
the second RS comprises the second downlink channel quality estimate,
the second downlink channel quality estimate is based on a second frequency resource of the one or more signals, and
the frequency band allocated for RS transmission includes the second frequency resource.
18. The UE of claim 17 , wherein the first downlink channel quality estimate comprises a first interference covariance matrix (R nn ) and the second downlink channel quality estimate comprises a second R nn , and wherein the first RS comprises a first sounding reference signal (SRS) and the second RS comprises a second SRS.
19. The UE of claim 17 , wherein the first frequency resource and the second frequency resource are determined based on a message received from the base station for triggering the UE to perform a RS transmission.
20. The UE of claim 19 , wherein the message comprises downlink control information for sounding reference signal (SRS) scheduling.
21. The UE of claim 19 , wherein the message identifies one of a plurality of configurations, each configuration corresponding to a different set of frequency resources.
22. The UE of claim 17 , wherein the first frequency resource and the second frequency resource are determined based on a range of the frequency band allocated for RS transmission.
23. The UE of claim 17 , wherein the first frequency resource and the second frequency resource are determined based on capabilities of the UE.
24. The UE of claim 17 , wherein the first frequency resource and the second frequency resource are determined based on time available between events of receiving a message indicating transmission of RS, receiving the one or more signals for use in estimating the channel quality, and transmitting the first RS.
25. The UE of claim 16 , wherein the frequency band allocated for RS transmission comprises resource blocks (RBs).
26. The UE of claim 16 , wherein:
the processor and the memory being configured to transmit the first RS comprises the processor and the memory being configured to transmit the first RS over all frequency resources of the frequency band; and
the first frequency resource corresponds to all frequency resources of the frequency band.
27. The UE of claim 16 , wherein:
the processor and the memory being configured to transmit the first RS comprises the processor and the memory being configured to transmit the first RS over all frequency resources of the frequency band at a first time; and
the first frequency resource corresponds to a first subset of the frequency resources of the frequency band.
28. The UE of claim 27 , wherein the processor and the memory are further configured:
transmit a second RS precoded with a second downlink channel quality estimate, wherein:
the second RS comprises the second downlink channel quality estimate,
the second downlink channel quality estimate is based on a second frequency resource of the one or more signals,
the frequency band allocated for RS transmission includes the second frequency resource,
the processor and the memory being configured to transmit the second RS comprises the processor and the memory being configured to transmit the second RS over all the frequency resources of the frequency band at a second time, and
the second frequency resource corresponds to a second subset of the frequency resources of the frequency band.
29. The UE of claim 16 , wherein:
the processor and the memory being configured to transmit the first RS comprises the processor and the memory being configured to transmit the first RS over the first frequency resource; and
the first frequency resource corresponds to a first subset of the frequency resources of the frequency band.
30. The UE of claim 29 , wherein the processor and the memory are further configured to:
transmit a second RS precoded with a second downlink channel quality estimate, wherein:
the second RS comprises the second downlink channel quality estimate,
the second downlink channel quality estimate is based on a second frequency resource of the one or more signals,
the frequency band allocated for RS transmission includes the second frequency resource,
the processor and the memory being configured to transmit the second RS comprises the processor and the memory being configured to transmit the second RS the second frequency resource, and
the second frequency resource corresponds to a second subset of the frequency resources of the frequency band.