Contention based uplink transmissions for latency reduction
Contention-based uplink communications within a wireless communications system are provided in which a user equipment (UE) may transmit data to a base station autonomously, and thereby reduce delay with established procedures for allocating uplink resources to a UE. A base station may allocate contention-based uplink resources from a set of available uplink resources. A UE may determine that data is to be transmitted using contention-based uplink resources, identify available contention-based resources allocated by the base station, and may autonomously transmit the data using the allocated contention-based resources. The contention-based uplink resources may include a subset of available physical uplink shared channel (PUSCH) resources. The contention-based PUSCH resources may include allocated bins, and a UE may select CB-PUSCH resources from one of the bins for transmission of the uplink data.
1. A method for wireless communication, comprising:
identifying data to be transmitted using a set of uplink resources;
determining that an elapsed time since a prior scheduling request (SR) was transmitted exceeds a threshold;
determining that the data is to be transmitted using a contention-based subset of the uplink resources based at least in part on determining that the elapsed time exceeds the threshold; and
transmitting the data using the contention-based subset of the uplink resources.
2. The method of claim 1 , further comprising:
identifying one or more resources of the contention-based subset of the uplink resources based at least in part on determining that the data is to be transmitted using the contention-based subset of the uplink resources; and
autonomously transmitting the data using the identified one or more resources of the contention-based subset of the uplink resources.
3. The method of claim 2 , further comprising:
determining a modulation and coding scheme (MCS) for transmitting the data based at least in part on the contention-based subset of the uplink resources.
4. The method of claim 2 , further comprising:
determining a transmit power from a set of available transmit powers for transmitting the data based at least in part on the contention-based subset of the uplink resources.
5. The method of claim 2 , wherein identifying the one or more resources of the contention-based subset of the uplink resources comprises:
identifying one or more allocated bins for contention-based uplink transmissions; and
selecting a bin of the one or more allocated bins for transmitting the data.
6. The method of claim 5 , wherein selecting the bin of the one or more allocated bins comprises:
randomly selecting the bin from a plurality of allocated bins.
7. The method of claim 5 , wherein selecting the bin of the one or more allocated bins comprises:
identifying one or more characteristics of the data to be transmitted; and
selecting the bin based at least in part on the one or more characteristics.
8. The method of claim 7 , wherein the one or more characteristics comprise at least one of an amount of data to be transmitted, a type of traffic associated with the data to be transmitted, or a source of the data to be transmitted, or any combination thereof.
9. The method of claim 5 , further comprising:
receiving signaling indicating the one or more allocated bins, wherein the signaling comprises at least one of RRC signaling, a system information block (SIB), or physical downlink control channel (PDCCH) signaling, or any combination thereof.
10. The method of claim 2 , further comprising:
receiving a set of radio network temporary identifiers (RNTIs);
determining a RNTI from the set of RNTIs to be used for monitoring a physical downlink control channel (PDCCH); and
monitoring the PDCCH for the determined RNTI; and
wherein the one or more resources of the contention-based subset of the uplink resources is identified based at least in part on the monitoring.
11. The method of claim 1 , wherein the data comprises at least one of a data payload, an identification of a device transmitting the data, or a buffer status report indicating an amount of data that is to be transmitted, or any combination thereof.
12. The method of claim 1 , further comprising:
determining that a negative acknowledgment message or that no acknowledgement message is received in response to transmitting the data using the contention-based subset of the uplink resources; and
transmitting another SR associated with the data based at least in part on determining that the negative acknowledgment message or that no acknowledgment message is received.
13. The method of claim 1 , wherein the data comprises a buffer status report (BSR) that indicates an amount of data to be transmitted and an identifier of a device transmitting the BSR.
14. The method of claim 1 , further comprising:
determining that a buffer status report (BSR) is to be transmitted using the contention-based subset of the uplink resources; and
autonomously transmitting the BSR using the contention-based subset of the uplink resources.
15. The method of claim 14 , wherein the BSR is transmitted using an identified BSR resource within the contention-based subset of the uplink resources.
16. The method of claim 15 , wherein the identified BSR resource comprises one code division multiplexing (CDM) code over one resource block of the contention-based subset of the uplink resources.
17. The method of claim 14 , further comprising:
receiving an uplink grant responsive to the BSR transmission based at least in part on an unsuccessful transmission of the data using the contention-based subset of the uplink resources.
18. The method of claim 14 , wherein the BSR is transmitted when data to be transmitted exceeds a threshold amount of data for transmission using the contention-based subset of the uplink resources.
19. The method of claim 14 , further comprising:
receiving an uplink grant allocating one or more resources of a grant-based subset of the uplink resources responsive to the transmission of the BSR.
20. The method of claim 1 , further comprising:
determining that the contention-based subset of the uplink resources supports a concurrent scheduling request (SR) associated with the data; and
transmitting the SR concurrently with the data using the contention-based subset of the uplink resources.
21. An apparatus for wireless communication, comprising:
a processor;
memory in electronic communication with the processor; and
instructions stored in the memory, the instructions being executable by the processor to:
identify data to be transmitted using a set of uplink resources;
determine that an elapsed time since a prior scheduling request (SR) was transmitted exceeds a threshold;
determine that the data is to be transmitted using a contention-based subset of the uplink resources based at least in part on determining that the elapsed time exceeds the threshold; and
transmit the data using the contention-based subset of the uplink resources.
22. The apparatus of claim 21 , wherein the instructions are operable to cause the apparatus to:
identify one or more resources of the contention-based subset of the uplink resources based at least in part on determining that the data is to be transmitted using the contention-based subset of the uplink resources; and
autonomously transmit the data using the identified one or more resources of the contention-based subset of the uplink resources.
23. The apparatus of claim 21 , wherein the instructions are operable to cause the apparatus to:
determine that a buffer status report (BSR) is to be transmitted using the contention-based subset of the uplink resources; and
autonomously transmit the BSR using the contention-based subset of the uplink resources.
24. The apparatus of claim 21 , wherein the instructions are operable to cause the apparatus to:
determine that the contention-based subset of the uplink resources supports a concurrent scheduling request (SR) associated with the data; and
transmit the SR concurrently with the data using the contention-based subset of the uplink resources.
25. An apparatus for wireless communication, comprising:
means for identifying data to be transmitted using a set of uplink resources;
means for determining that an elapsed time since a prior scheduling request (SR) was transmitted exceeds a threshold;
means for determining that the data is to be transmitted using a contention-based subset of the uplink resources based at least in part on determining that the elapsed time exceeds the threshold; and
means for transmitting the data using the contention-based subset of the uplink resources.
26. A non-transitory computer-readable medium storing computer-executable code for wireless communication, the code comprising instructions executable to:
identify data to be transmitted using a set of uplink resources;
determine that an elapsed time since a prior scheduling request (SR) was transmitted exceeds a threshold;
determine that the data is to be transmitted using a contention-based subset of the uplink resources based at least in part on determining that the elapsed time exceeds the threshold; and
transmit the data using the contention-based subset of the uplink resources.