Efficient usage of resources in an uplink split bearer configuration
Certain aspects of the present disclosure provide techniques for wireless communications by a user equipment (UE) capable of establishing a split bearer involving at least primary and secondary radio link control (RLC) entities. The techniques generally include deciding, based on one or more conditions, whether to submit a Packet Data Convergence Protocol (PDCP) protocol data unit (PDU) to the primary RLC entity or the secondary RLC entity according to one or more rules and submitting the PDCP PDU to at least one of the primary or secondary RLC entities in accordance with the decision.
1. A method for wireless communication by a user equipment (UE), comprising:
establishing a split bearer involving at least primary and secondary radio link control (RLC) entities;
deciding, based on one or more conditions, whether to submit a Packet Data Convergence Protocol (PDCP) protocol data unit (PDU) to the primary RLC entity or the secondary RLC entity according to one or more rules, wherein the one or more conditions comprise an outstanding PDCP PDU volume falling below a threshold value in the middle of transmitting a transport block (TB); and
submitting the PDCP PDU to at least one of the primary or secondary RLC entities in accordance with the decision.
2. The method of claim 1 , wherein the one or more conditions are designed to avoid wastage of network provided resources.
3. The method of claim 1 , wherein the UE is operating in a dual connectivity (DC) mode where the primary RLC entity is associated with a first radio access network (RAN) and the secondary RLC entity is associated with a second RAN.
4. The method of claim 1 , wherein the UE is operating in a dual connectivity (DC) mode where the primary RLC entity is associated with a first cell and the secondary RLC entity is associated with a second cell.
5. The method of claim 1 , wherein
deciding whether to submit a PDCP PDU to the primary RLC entity or the secondary RLC entity comprises deciding to submit the PDCP PDU to the secondary RLC entity.
6. The method of claim 5 , wherein the UE submits the PDCP PDUs to the secondary RLC entity until resources of a grant are exhausted.
7. The method of claim 1 , wherein
deciding whether to submit a PDCP PDU to the primary RLC entity or the secondary RLC entity comprises deciding to submit the PDCP PDU only to the secondary RLC entity.
8. The method of claim 7 , wherein the secondary RLC entity builds complete RLC PDUs without segmentation.
9. The method of claim 7 , wherein the secondary RLC entity is allowed to build RLC PDUs with segmentation.
10. The method of claim 9 , further comprising sending, on the primary RLC entity, the same PDCP PDUs that got segmented on the secondary RLC entity.
11. The method of claim 1 , wherein:
the one or more conditions comprise a block error rate (BLER) of at least one of the first or second RLC entities above a threshold value; and further comprising refraining from providing PDCP PDUs to the RLC entity with the BLER above the threshold value.
12. The method of claim 11 , further comprising refraining from reporting a non-zero buffer status report (BSR) for the RLC entity with the BLER above the threshold value.
13. The method of claim 1 , wherein:
the one or more conditions comprise a block error rate (BLER) of at least one of the first or second RLC entities above a threshold value; and further comprising retransmitting one or more PDCP PDUs, originally transmitted on the RLC entity with the BLER above the threshold value for which RLC acknowledgments have not been received, on the other RLC entity.
14. The method of claim 1 , wherein the primary RLC entity belongs to a master cell group (MCG) and the secondary RLC entity belongs to a secondary cell group (SCG).
15. The method of claim 14 , wherein:
the one or more conditions comprise a detection of a radio link failure (RLF) of one of a SCG RLC or an MCG RLC; and
the method further comprises retransmitting the submitted PDCP PDU on the other of the SCG RLC or the MCG RLC.
16. The method of claim 14 , wherein:
the one or more conditions comprise a data volume being below a threshold; and
the method further comprises submitting a new PDCP PDU on a MCG RLC even if data volume and primary configurations indicate that the new PDCP PDU should be submitted on a SCG RLC.
17. An apparatus for wireless communication by a user equipment (UE), comprising:
means for establishing a split bearer involving at least primary and secondary radio link control (RLC) entities;
means for deciding, based on one or more conditions, whether to submit a Packet Data Convergence Protocol (PDCP) protocol data unit (PDU) to the primary RLC entity or the secondary RLC entity according to one or more rules, wherein the one or more conditions comprise an outstanding PDCP PDU volume falling below a threshold value in the middle of transmitting a transport block (TB); and
means for submitting the PDCP PDU to at least one of the primary or secondary RLC entities in accordance with the decision.
18. The apparatus of claim 17 , wherein the one or more conditions are designed to avoid wastage of network provided resources.
19. The apparatus of claim 17 , wherein the UE is configured to operate in a dual connectivity (DC) mode where the primary RLC entity is associated with a first radio access network (RAN) and the secondary RLC entity is associated with a second RAN.
20. The apparatus of claim 17 , wherein the UE is configured to operate in a dual connectivity (DC) mode where the primary RLC entity is associated with a first cell and the secondary RLC entity is associated with a second cell.
21. The apparatus of claim 17 , wherein deciding whether to submit a PDCP PDU to the primary RLC entity or the secondary RLC entity comprises deciding to submit the PDCP PDU to the secondary RLC entity.
22. The apparatus of claim 21 , wherein the UE is configured to submit the PDCP PDUs to the secondary RLC entity until resources of a grant are exhausted.
23. The apparatus of claim 21 , wherein the secondary RLC entity is configured to build complete RLC PDUs without segmentation.
24. The apparatus of claim 21 , wherein the secondary RLC entity is allowed to build RLC PDUs with segmentation.
25. The apparatus of claim 24 , further comprising means for sending, on the primary RLC entity, the same PDCP PDUs that got segmented on the secondary RLC entity.
26. The apparatus of claim 17 , wherein:
the one or more conditions comprise a block error rate (BLER) of at least one of the first or second RLC entities above a threshold value; and
the UE is configured to refrain from providing PDCP PDUs to the RLC entity with the BLER above the threshold value.
27. The apparatus of claim 26 , further comprising means for refraining from reporting a non-zero buffer status report (BSR) for the RLC entity with the BLER above the threshold value.
28. The apparatus of claim 17 , wherein:
the one or more conditions comprise a block error rate (BLER) of at least one of the first or second RLC entities above a threshold value; and
the UE is configured to retransmit one or more PDCP PDUs, originally transmitted on the RLC entity with the BLER above the threshold value for which RLC acknowledgments have not been received, on the other RLC entity.
29. An apparatus for wireless communication by a user equipment (UE), comprising:
at least one processor and a memory configured to
establish a split bearer involving at least primary and secondary radio link control (RLC) entities,
decide, based on one or more conditions, whether to submit a Packet Data Convergence Protocol (PDCP) protocol data unit (PDU) to the primary RLC entity or the secondary RLC entity according to one or more rules, wherein the one or more conditions comprise an outstanding PDCP PDU volume falling below a threshold value in the middle of transmitting a transport block (TB); and
submit the PDCP PDU to at least one of the primary or secondary RLC entities in accordance with the decision.
30. A non-transitory computer readable medium having instructions stored thereon for:
establishing a split bearer involving at least primary and secondary radio link control (RLC) entities;
deciding, based on one or more conditions, whether to submit a Packet Data Convergence Protocol (PDCP) protocol data unit (PDU) to the primary RLC entity or the secondary RLC entity according to one or more rules, wherein the one or more conditions comprise an outstanding PDCP PDU volume falling below a threshold value in the middle of transmitting a transport block (TB); and
submitting the PDCP PDU to at least one of the primary or secondary RLC entities in accordance with the decision.