Implicit DRX cycle length adjustment control in LTE
A method for controlling discontinuous reception in a wireless transmit/receive unit includes defining a plurality of DRX levels, wherein each DRX level includes a respective DRX cycle length and transitioning between DRX levels based on a set of criteria. The transitioning may be triggered by implicit rules.
1. A method for controlling discontinuous reception (DRX) in a wireless transmit/receive unit (WTRU), the method comprising:
the WTRU receiving a DRX configuration comprising a plurality of DRX cycle lengths;
the WTRU performing DRX using a shorter DRX cycle length of the plurality of DRX cycle lengths;
the WTRU setting a WTRU timer upon initiating DRX operation using the shorter DRX cycle length, wherein the WTRU timer is associated with a length of time during which the WTRU performs DRX using the shorter DRX cycle length prior to transitioning to a longer DRX cycle length of the plurality of DRX cycle lengths;
the WTRU determining that the WTRU timer has expired; and
the WTRU transitioning from DRX operation using the shorter DRX cycle length to DRX operation using the longer DRX cycle length in response to determining that the WTRU timer has expired.
2. The method as in claim 1 , wherein the WTRU timer is synchronized with a base station timer.
3. The method as in claim 1 , wherein the longer DRX cycle length is a multiple of the shorter DRX cycle length.
4. The method as in claim 1 , wherein each of the plurality of DRX cycle lengths is a function of a shortest DRX cycle length.
5. The method as in claim 4 , wherein the shorter DRX cycle length is the shortest DRX cycle length of the plurality of DRX cycle lengths.
6. The method as in claim 1 , further comprising the WTRU performing DRX using the longer DRX cycle length prior to the WTRU performing DRX using the shorter DRX cycle length.
7. The method as in claim 1 , wherein the longer DRX cycle length is a default DRX cycle length.
8. The method as in claim 1 , wherein transitioning between DRX cycle lengths is implemented at a Medium Access Control (MAC) level.
9. The method as in claim 1 , further comprising the WTRU resetting the WTRU timer upon transmission activity.
10. The method as in claim 1 , wherein a value for the WTRU timer is received from an evolved Node-B (eNB) via higher layer signaling.
11. A wireless transmit receive unit (WTRU) comprising a processor, the processor configured to:
receive a discontinuous reception (DRX) configuration comprising a plurality of DRX cycle lengths;
perform DRX using a shorter DRX cycle length of the plurality of DRX cycle lengths;
set a WTRU timer upon initiating DRX operation using the shorter DRX cycle length, wherein the WTRU timer is associated with a length of time during which the WTRU is configured to operate using the shorter DRX cycle length, and if no new transmissions have been received during the length of time the WTRU is configured to transition to a longer DRX cycle length of the plurality of DRX cycle lengths;
determine that the WTRU timer has expired; and
transition the WTRU from DRX operation using the shorter DRX cycle length to DRX operation using the longer DRX cycle length in response to determining that the WTRU timer has expired.
12. The WTRU as in claim 11 , wherein the WTRU timer is synchronized with a base station timer.
13. The WTRU as in claim 11 , wherein the processor is further configured to perform DRX using the longer DRX cycle length prior to performing DRX using the shorter DRX cycle length.
14. The WTRU as in claim 11 , wherein each of the plurality of DRX cycle lengths is a multiple of the shorter DRX cycle length.
15. The WTRU as in claim 14 , wherein the shorter DRX cycle length is a shortest DRX cycle length of the plurality of DRX cycle lengths.
16. The WTRU as in claim 11 , wherein the WTRU is configured to implement transitioning between DRX cycle lengths at a Medium Access Control (MAC) level.
17. The WTRU as in claim 11 , wherein the processor is further configured to reset the WTRU timer upon transmission activity.
18. The WTRU as in claim 11 , wherein the processor is configured to receive a value for the WTRU timer from an evolved Node-B (eNB) via higher layer signaling.
19. An evolved Node B (eNB) comprising a processor configured to:
send a discontinuous reception (DRX) configuration to a wireless transmit/receive unit (WTRU), the DRX configuration comprising a plurality of DRX cycle lengths;
determine that the WTRU has initiated DRX operation using a shorter DRX cycle length of the plurality of DRX cycle lengths;
set a base station timer upon determining that the WTRU has initiated DRX operation using the shorter DRX cycle length, the base station timer being synchronized with a WTRU timer used for DRX cycle length transitions at the WTRU and being associated with a length of time during which the WTRU performs DRX using the shorter DRX cycle length;
determine that the base station timer has expired; and
determine that the WTRU has transitioned from performing DRX using the shorter DRX cycle length to performing DRX using a longer DRX cycle length of the plurality of DRX cycle lengths in response to determining that the base station timer has expired.
20. The eNB as in claim 19 , wherein the eNB does not send an explicit indication to the WTRU that instructs the WTRU to transition from the shorter DRX cycle length to the longer DRX cycle length.
21. The method as in claim 1 , wherein the WTRU transitions from operation using the shorter DRX cycle length to operation using the longer DRX cycle length of the plurality of DRX cycle lengths without receiving an explicit indication from an evolved Node-B (eNB) that instructs the WTRU to transition from the shorter DRX cycle length to the longer DRX cycle length.
22. The WTRU as in claim 11 , wherein the processor is configured to transition the WTRU from operation using the shorter DRX cycle length to operation using the longer DRX cycle length of the plurality of DRX cycle lengths without receiving an explicit indication from an evolved Node-B (eNB) that instructs the WTRU to transition from the shorter DRX cycle length to the longer DRX cycle length.
23. The method as in claim 1 , wherein expiration of the WTRU timer is an implicit transition trigger to transition the WTRU from performing DRX using the shorter DRX cycle length to performing DRX using the longer DRX cycle length if no new transmissions have been received.
24. The WTRU as in claim 11 , wherein expiration of the WTRU timer is an implicit transition trigger to transition the WTRU from performing DRX using the shorter DRX cycle length to performing DRX using the longer DRX cycle length if no new transmissions have been received.
25. The method as in claim 1 , wherein the WTRU timer is implemented as a counter.
26. The WTRU as in claim 11 , wherein the WTRU is configured to implement the WTRU timer using a counter.