Low latency physical uplink control channel with scheduling request and channel state information
Methods, systems, and devices for wireless communication are described. A user equipment (UE) and a base station may use low latency communications to improve the throughput of a wireless link. To facilitate efficient low latency communication, the UE may send UE-initiated CSI reports in addition to periodic and base station-initiated reports. For example, the UE may, in various examples, send UE-initiated CSI reports using contention based spectrum, using a request-to-transmit, or using a CSI differential (i.e., an indicator of a change in channel conditions). The base station may schedule different UEs for uplink low latency communication by providing resources to each UE for CSI and scheduling requests (SRs) using coherent or non-coherent uplink transmissions. The CSI and SR may also be combined with uplink feedback.
1. A method of wireless communication, comprising:
determining a set of resources reserved for uplink control information (UCI), the set of resources comprising a first resource block and a second resource block, wherein a group of users corresponding to a first symbol of the first resource block is a same group of users corresponding to a second symbol of the second resource block; and
receiving at least one of a report with channel state information (CSI), a request for resources on which to send a CSI report, or signaling that indicates a change in CSI on resources of the set of reserved resources from a user equipment (UE), the receiving occurring during a first transmission time interval (TTI) duration in a system that supports operation with the first TTI duration and a second TTI duration that is greater than the first.
2. The method of claim 1 , further comprising:
transmitting signaling that indicates the set of reserved resources to the UE.
3. The method of claim 2 , wherein the signaling that indicates the set of reserved resources includes a downlink grant.
4. The method of claim 1 , wherein the set of reserved resources includes resources reserved for a scheduling request (SR), the CSI report, or hybrid automatic repeat request (HARQ) feedback, or any combination thereof.
5. The method of claim 1 , wherein the set of reserved resources is based at least in part on a number UEs for which the set of reserved resources is allocated.
6. The method of claim 5 , wherein the number of UEs includes coherent users or non-coherent users, or both.
7. The method of claim 5 , wherein the set of reserved resources is periodically allocated to different UEs within the system.
8. The method of claim 5 , further comprising:
transmitting to the UE signaling indicating that a TTI having the first TTI duration is reserved for CSI reporting.
9. The method of claim 5 , further comprising:
receiving a random access channel (RACH) message from the UE; and
transmitting message responsive to the RACH message to the UE, wherein the responsive message indicates the set of reserved resources.
10. The method of claim 9 , further comprising:
transmitting to a different UE signaling that indicates a reassignment of the reserved resources.
11. The method of claim 1 , wherein the first resource block and the second resource block each comprise a two symbol TTI.
12. An apparatus for wireless communication, comprising:
a processor;
memory coupled with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
determine a set of resources reserved for uplink control information (UCI), the set of resources comprising a first resource block and a second resource block, wherein a group of users corresponding to a first symbol of the first resource block is a same group of users corresponding to a second symbol of the second resource block; and
receive at least one of a report with channel state information (CSI), a request for resources on which to send a CSI report, or signaling that indicates a change in CSI on resources of the set of reserved resources from a user equipment (UE), during a first transmission time interval (TTI) duration in a system that supports operation with the first TTI duration and a second TTI duration that is greater than the first.
13. The apparatus of claim 12 , wherein the instructions are further executable by the processor to cause the apparatus to:
transmit signaling that indicates the set of reserved resources to the UE, wherein the signaling that indicates the set of reserved resources includes a downlink grant.
14. The apparatus of claim 12 , wherein the set of reserved resources is based at least in part on a number UEs for which the set of reserved resources is allocated.
15. The apparatus of claim 14 , wherein the number of UEs includes coherent users or non-coherent users, or both.
16. The apparatus of claim 14 , wherein the set of reserved resources is periodically allocated to different UEs within the system.
17. The apparatus of claim 14 , wherein the instructions are further executable by the processor to cause the apparatus to:
transmit to the UE signaling indicating that a TTI having the first TTI duration is reserved for CSI reporting.
18. The apparatus of claim 14 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive a random access channel (RACH) message from the UE; and
transmit message responsive to the RACH message to the UE, wherein the responsive message indicates the set of reserved resources.
19. The apparatus of claim 12 , wherein the first resource block and the second resource block each comprise a two symbol TTI.
20. An apparatus for wireless communication, comprising:
means for determining a set of resources reserved for uplink control information (UCI), the set of resources comprising a first resource block and a second resource block, wherein a group of users corresponding to a first symbol of the first resource block is a same group of users corresponding to a second symbol of the second resource block; and
means for receiving at least one of a report with channel state information (CSI), a request for resources on which to send a CSI report, or signaling that indicates a change in CSI on resources of the set of reserved resources from a user equipment (UE), during a first transmission time interval (TTI) duration in a system that supports operation with the first TTI duration and a second TTI duration that is greater than the first.
21. The apparatus of claim 20 , further comprising:
means for transmitting signaling that indicates the set of reserved resources to the UE, wherein the signaling that indicates the set of reserved resources includes a downlink grant.
22. The apparatus of claim 20 , wherein the set of reserved resources is based at least in part on a number UEs for which the set of reserved resources is allocated.
23. The apparatus of claim 22 , wherein the number of UEs includes coherent users or non-coherent users, or both.
24. The apparatus of claim 22 , wherein the set of reserved resources is periodically allocated to different UEs within the system.
25. The apparatus of claim 22 , further comprising:
means for transmitting to the UE signaling indicating that a TTI having the first TTI duration is reserved for CSI reporting.
26. The apparatus of claim 22 , further comprising:
means for receiving a random access channel (RACH) message from the UE; and
means for transmitting message responsive to the RACH message to the UE, wherein the responsive message indicates the set of reserved resources.
27. The apparatus of claim 20 , wherein the first resource block and the second resource block each comprise a two symbol TTI.
28. A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:
determine a set of resources reserved for uplink control information (UCI), the set of resources comprising a first resource block and a second resource block, wherein a group of users corresponding to a first symbol of the first resource block is a same group of users corresponding to a second symbol of the second resource block; and
receive at least one of a report with channel state information (CSI), a request for resources on which to send a CSI report, or signaling that indicates a change in CSI on resources of the set of reserved resources from a user equipment (UE), during a first transmission time interval (TTI) duration in a system that supports operation with the first TTI duration and a second TTI duration that is greater than the first.
29. The non-transitory computer-readable medium of claim 28 , wherein the code further includes instructions executable by the processor to:
transmit signaling that indicates the set of reserved resources to the UE, wherein the signaling that indicates the set of reserved resources includes a downlink grant.
30. The non-transitory computer-readable medium of claim 28 , wherein the first resource block and the second resource block each comprise a two symbol TTI.