Method and system for battery energy savings for carrier aggregation
A method at a user equipment having a scheduling carrier and at least one scheduled carrier, the method receiving, at a first subframe from the scheduling carrier, a downlink control indication containing a downlink assignment for the user equipment on the scheduled carrier; and turning on a receiver of the user equipment for the scheduled carrier at a future downlink subframe based on the downlink assignment. Further, a method, at a scheduling cell having a scheduling carrier, for scheduling downlink data reception on a scheduled carrier, the method setting a time skew for the scheduled carrier such that a data transmission start time for a subframe at the scheduled carrier is greater than a blind latency decode time on the scheduling carrier.
1. A method at a user equipment having a scheduling carrier and at least one scheduled carrier, the method comprising:
receiving a first higher layer indication from the scheduling carrier to turn on future downlink subframe scheduling for each of the at least one scheduled carrier;
when future downlink subframe scheduling is turned on:
receiving, at a first subframe from the scheduling carrier, a first downlink control indication containing a first downlink assignment for the user equipment on a selected carrier of the at least one scheduled carrier;
turning on a receiver of the user equipment for the selected carrier at a future downlink subframe based on the first downlink assignment;
receiving a second higher layer indication from the scheduling carrier to turn off future downlink subframe scheduling for each of the at least one scheduled carrier;
when future downlink subframe scheduling is turned off:
receiving, at a second subframe from the scheduling carrier, a second downlink control indication containing a second downlink assignment for the user equipment on the selected carrier; and
turning on the receiver of the user equipment for the selected carrier during the second subframe based on the second downlink assignment;
wherein the first higher layer indication is distinct from the first downlink control indication.
2. The method of claim 1 , wherein the future downlink subframe is the next available downlink subframe.
3. The method of claim 1 , wherein the higher layer indication is sent over radio resource control or medium access control signaling.
4. The method of claim 1 , wherein an unused value in a CrossCarrierSchedulingConfig IE pdsch-Start field is used for the higher layer signaling.
5. The method of claim 1 , further comprising receiving, on a downlink control indication of the selected carrier, at the future downlink subframe, an indication to override the existing downlink assignment.
6. A user equipment having a scheduling carrier and at least one scheduled carrier comprising:
a processor; and
a communications subsystem;
wherein the user equipment is configured to:
receive a first higher layer indication from the scheduling carrier to turn on future downlink subframe scheduling for each of the at least one scheduled carrier;
when future downlink subframe scheduling is turned on:
receive at a first subframe from the scheduling carrier, a first downlink control indication containing a first downlink assignment for the user equipment on a selected carrier of the at least one scheduled carrier;
turn on a receiver of the user equipment for the selected carrier at a future downlink subframe based on the first downlink assignment;
receive a second higher layer indication from the scheduling carrier to turn off future downlink subframe scheduling for each of the at least one scheduled carrier;
when future downlink subframe scheduling is turned off:
receive, at a second subframe from the scheduling carrier, a second downlink control indication containing a second downlink assignment for the user equipment on the selected carrier; and
turn on the receiver of the user equipment for the selected carrier during the second subframe based on the second downlink assignment;
wherein the first higher layer indication is distinct from the first downlink control indication.
7. The user equipment of claim 6 , wherein the future downlink subframe is the next available downlink subframe.
8. The user equipment of claim 6 , wherein the higher layer indication is sent over radio resource control or medium access control signaling.
9. The user equipment of claim 6 , wherein an unused value in a CrossCarrierSchedulingConfig IE pdsch-Start field is used for the higher layer signaling.
10. The user equipment of claim 6 , further configured to receive, on a downlink control indication of the selected carrier, at the future downlink subframe, an indication to override the existing downlink assignment.
11. A method, at a scheduling cell, for scheduling downlink data reception for a scheduled cell, the method comprising,
providing a first indication to at least one user equipment that downlink assignments on any carrier of at least one scheduled carrier for the scheduled cell are for future downlink subframes;
when future downlink subframe scheduling is turned on:
transmitting a first downlink assignment to the at least one user equipment on a selected carrier of the at least one scheduled carrier;
determining a future downlink subframe;
transmitting data corresponding to the first downlink assignment during the future downlink subframe on the selected carrier;
providing a second indication to the at least one user equipment that downlink assignments on any carrier of the at least one scheduled carrier for the scheduled cell are for a current downlink subframe;
when future downlink subframe scheduling is turned off:
transmitting a second downlink assignment to the at least one user equipment on the selected carrier;
transmitting data corresponding to the second downlink assignment during the current downlink subframe on the selected carrier;
wherein the first indication is distinct from the first downlink assignment.
12. The method of claim 11 , wherein the first indication is sent over radio resource control or medium access control signaling.
13. The method of claim 12 , wherein an unused value in a CrossCarrierSchedulingConfig IE pdsch-Start field is used for the first indication.
14. The method of claim 11 , wherein the future downlink subframe is the next downlink subframe after the downlink assignment.
15. A network element for scheduling downlink data reception for a scheduled cell, the network element comprising:
a processor; and
a communications system,
wherein the network element is configured to:
provide a first indication to at least one user equipment that downlink assignments on any carrier of at least one scheduled carrier for the scheduled cell are for future downlink subframes;
when future downlink subframe scheduling is turned on:
transmit a first downlink assignment to the at least one user equipment on a selected carrier of the at least one scheduled carrier;
determine a future downlink subframe;
transmit data corresponding to the first downlink assignment during the future downlink subframe on the selected carrier;
provide a second indication to the at least one user equipment that downlink assignments on any carrier of the at least one carrier for the scheduled cell are for a current downlink subframe;
when future downlink subframe scheduling is turned off:
transmit a second downlink assignment to the at least one user equipment on the selected carrier;
transmit data corresponding to the second downlink assignment during the current downlink subframe on the selected carrier;
wherein the first indication is distinct from the first downlink assignment.
16. The network element of claim 15 , wherein the first indication is sent over radio resource control or medium access control signaling.
17. The network element of claim 16 , wherein an unused value in a CrossCarrierSchedulingConfig IE pdsch-Start field is used for the first indication.
18. The network element of claim 15 , wherein the future downlink subframe is the next downlink subframe after the downlink assignment.