Method and apparatus for PCDP discard
A method and apparatus for discarding a packet data convergence protocol (PDCP) service data unit (SDU) are disclosed. A PDCP layer sets a timer and discards a PDCP SDU upon expiration of the timer. The timer may be set upon receiving the PDCP SDU from an upper layer or upon submitting the PDCP SDU to a lower layer for transmission. The timer and a radio link control (RLC) discard timer may be coordinated. Alternatively, the PDCP layer may discard the PDCP SDU based on a notification from an RLC layer or based on a PDCP status report.
1. A method for discarding a packet data convergence protocol (PDCP) packet, the method comprising:
a PDCP entity starting a timer upon reception of a PDCP service data unit (SDU) from an upper layer;
the PDCP entity sending a corresponding PDCP PDU to a radio link control (RLC) entity;
on condition that the timer expires, the PDCP entity discarding the PDCP SDU; and
the PDCP entity sending an indication of the discard to the RLC entity.
2. The method of claim 1 , further comprising the PDCP entity receiving a PDCP status report, wherein the PDCP status report acknowledges receipt by a receiving PDCP entity of at least one PDCP protocol data unit (PDU).
3. The method of claim 2 , further comprising the PDCP entity discarding the at least one PDCP PDU and at least one corresponding PDCP SDU .
4. The method of claim 2 , wherein the PDCP status report is received during a handover.
5. The method of claim 1 , further comprising the PDCP entity creating the corresponding PDCP PDU, wherein creating the corresponding PDCP PDU comprises:
the PDCP entity assigning a sequence number (SN) to the PDCP SDU; and
the PDCP entity performing header compression on the PDCP SDU .
6. The method of claim 1 , further comprising:
the RLC entity discarding an RLC SDU associated with the corresponding PDCP PDU based on receiving the indication from the PDCP entity.
7. The method of claim 1 , wherein a separate timer is started for each PDCP SDU that includes user data received from an upper layer.
8. The method of claim 1 , further comprising the PDCP entity transmitting a PDCP Control PDU.
9. The method of claim 1 , wherein a threshold value of the timer is configured at a radio resource control (RRC) layer.
10. The method of claim 9 , wherein the threshold value of the timer is configured on a per-radio bearer (RB) basis.
11. The method of claim 1 , wherein the timer and an RLC discard timer are coordinated.
12. An evolved Node B (eNB) for discarding a packet data convergence protocol (PDCP) packet, the eNB comprising:
a PDCP entity configured to:
start a timer upon reception of a PDCP service data unit (SDU) from an upper layer,
send a corresponding PDCP PDU to a radio link control (RLC) entity,
discard the PDCP SDU on condition that the timer expires, and
send an indication of the discard to the RLC entity.
13. The eNB of claim 12 , wherein the PDCP entity is further configured to receive a PDCP status report, wherein the PDCP status report acknowledges receipt by a receiving PDCP entity of at least on PDCP protocol data unit (PDU).
14. The eNB of claim 13 , wherein the PDCP entity is further configured to discard the at least one PDCP PDU and at least one corresponding PDCP SDU.
15. The eNB of claim 13 , wherein the PDCP entity is configured to receive the PDCP status report during a handover.
16. The eNB of claim 13 , wherein the PDCP entity is configured to transmit a PDCP Control PDU.
17. The eNB of claim 12 , wherein the PDCP entity is further configured to create the corresponding PDCP PDU and creating the corresponding PDCP PDU comprises:
the PDCP entity assigning a sequence number (SN) to the PDCP SDU; and
the PDCP entity performing header compression on the PDCP SDU.
18. The eNB of claim 12 , wherein the eNB further comprises the RLC entity, and the RLC entity is configured to discard an RLC SDU associated with the corresponding PDCP PDU based on receiving the indication from the PDCP entity.
19. The eNB of claim 12 , wherein the PDCP entity is configured to start a separate timer for each PDCP SDU that includes user data received from an upper layer.
20. The eNB of claim 12 , wherein a threshold value of the timer is configured at a radio resource control (RRC) layer.
21. The eNB of claim 20 , wherein the threshold value of the timer is configured on a per-radio bearer (RB) basis.
22. A wireless transmit/receive unit (WTRU) configured to discard a packet data convergence protocol (PDCP) packet, the WTRU comprising:
a PDCP entity configured to:
start a timer upon reception of a PDCP service data unit (SDU) from an upper layer,
send a corresponding PDCP PDU to a radio link control (RLC) entity,
discard the PDCP SDU of the timer expires, and
send an indication of the discard to the RLC entity.
23. The WTRU of claim 22 , wherein the PDCP entity is further configured to receive a PDCP status report, wherein the PDCP status report acknowledges receipt by a receiving PDCP entity of at least on PDCP protocol data unit (PDU).
24. The WTRU of claim 23 , wherein the PDCP entity is further configured to discard the at least one PDCP PDU and at least one corresponding PDCP SDU.
25. The WTRU of claim 23 , wherein the PDCP entity is configured to receive the PDCP status report during a handover.
26. The WTRU of claim 23 , wherein the PDCP entity is configured to transmit a PDCP Control PDU.
27. The WTRU of claim 22 , wherein the PDCP entity is further configured to create the corresponding PDCP PDU and creating the corresponding PDCP PDU comprises:
the PDCP entity assigning a sequence number (SN) to the PDCP SDU; and
the PDCP entity performing header compression on the PDCP SDU.
28. The WTRU of claim 22 , wherein the WTRU further comprises the RLC entity, and the RLC entity is configured to discard an RLC SDU associated with the corresponding PDCP PDU based on receiving the indication from the PDCP entity.
29. The WTRU of claim 22 , wherein the PDCP entity is configured to start a separate timer for each PDCP SDU that includes user data received from an upper layer.
30. The WTRU of claim 22 , wherein a threshold value of the timer is configured at a radio resource control (RRC) layer.
31. The WTRU of claim 30 , wherein the threshold value of the timer is configured on a per-radio bearer (RB) basis.