Method and system for protocol layer enhancements in data offload over small cells
A method at a first wireless network element, the method receiving, from a second wireless network element, a plurality of packet data units (PDUs) for a user equipment; transmitting the PDUs to the user equipment (UE); compiling a PDU delivery status report in response to the transmitting of the PDUs; and sending the compiled PDU delivery status report to the second wireless network element.
1. A method at a first wireless network element comprising:
receiving, from a second wireless network element, a plurality of packet data unit (PDUs) for a user equipment;
transmitting the PDUs to the user equipment (UE);
receiving a discard indication from the second wireless network element to discard a subset of the PDUs; and
discarding the indicated subset of PDUs.
2. The method of claim 1 wherein a discard timer is maintained for a service data unit (SDU) associated with a PDU at the second wireless network element; and the discard indication is generated when the discard timer expires.
3. The method of claim 1 , wherein the first wireless network element is a small cell evolved Node B (eNB) and the second wireless network element is a macro cell eNB.
4. A method at a first wireless network element comprising:
sending, from the first wireless network element to a second wireless network element, a plurality of packet data unit (PDUs) for a user equipment;
receiving a PDU delivery status report from the second wireless network element;
discarding a service data unit (SDU) according to the PDU delivery status report;
determining discontinuance for offloading data of the UE to the second wireless network element; and
sending an offload reconfiguration request to the second wireless network element.
5. The method of claim 4 , wherein the discarding is applied to a SDU that is successfully delivered according to the PDU delivery status report.
6. The method of claim 4 , wherein the PDUs are packet data convergence protocol (PDCP) layer PDUs.
7. The method of claim 4 , wherein the PDU delivery status report is used to manage packet data convergence protocol (PDCP) layer SDUs at the first wireless network element.
8. The method of claim 4 , wherein the PDU delivery status report includes an indicator of PDUs successfully delivered.
9. The method of claim 4 , wherein the PDU delivery status report includes in indicator of PDUs that are not successfully delivered.
10. The method of claim 4 , wherein the PDU delivery status report is received over a backhaul interface between the second wireless network element and the first wireless network element.
11. The method of claim 10 , wherein the PDU delivery status report includes a bitmap of PDUs with consecutive sequence numbers.
12. The method of claim 11 , wherein the bitmap includes one or more bits for each of a plurality of PDUs.
13. The method of claim 4 , further comprising, prior to the receiving, sending a status request from the first wireless network element to the second wireless network element.
14. The method of claim 4 , further comprising:
providing a discard indication to the second wireless network element to discard a subset of the PDUs.
15. The method of claim 4 , wherein a discard timer is maintained at the second wireless network element for a PDU, the method further comprising:
receiving a report from the second wireless network element for one or more PDUs for which the discard timer has expired.
16. The method of claim 4 , wherein the second wireless network element is a small cell evolved Node B (eNB) and the first wireless network element is a macro cell eNB.