Power savings for downlink channel monitoring in narrowband systems

1. A method for wireless communications by a user equipment (UE), comprising:

determining whether a downlink data channel with semi-persistent scheduling (SPS) is present in a subframe, wherein the determining comprises at least one of:

detecting whether demodulation reference signals (DMRS) are present in one or more symbols in the subframe; or

performing energy detection on one or more frequency tones associated with a decoding candidate for the downlink data channel with SPS in the subframe; and

entering a low power mode for a remainder of the subframe based on a determination that the downlink data channel with SPS is not present in the subframe.

2. The method of claim 1 , wherein the low power mode includes skipping at least one of: monitoring of or receiving of one or more signals.

3. A method for wireless communications by a user equipment (UE), comprising:

decoding signaling, during a subframe, including an indication that a downlink control channel is not present in the subframe;

determining during the subframe, without decoding the downlink control channel, that the downlink control channel is not present in the subframe, wherein the determination is based on the indication in the decoded signaling; and

entering a low power mode for a remainder of the subframe based on the determination.

4. The method of claim 3 , wherein the determining comprises determining the downlink control channel is not present within one or more narrowband regions within a wider system bandwidth in the subframe.

5. The method of claim 3 , wherein the downlink control channel comprises an enhanced physical downlink control channel (EPDCCH), a machine type communications physical downlink control channel (MPDCCH), or a narrowband physical downlink control channel (NPDCCH).

6. The method of claim 3 , wherein the signaling including the indication that the downlink control channel is not present is received in a legacy physical downlink control channel (PDCCH) region.

7. The method of claim 6 , wherein the signaling including the indication that the downlink control channel is not present punctures the legacy PDCCH or is rate-matched around the legacy PDCCH.

8. The method of claim 3 , further comprising:

receiving other signaling indicating a location of the signaling including the indication that the downlink control channel is not present in the subframe; and

monitoring for the signaling including the indication that the downlink control channel is not present in the subframe at the indicated location.

9. The method of claim 3 , further comprising:

receiving a control format indicator (CFI) field; and

deriving a location of the signaling including the indication that the downlink control channel is not present in the subframe based on the received CFI.

10. The method of claim 3 , further comprising:

determining a grouping associated with the signaling including the indication that the downlink control is not present in the subframe; and

monitoring for the signaling including the indication that the downlink control is not present in the subframe based on the determined grouping.

11. The method of claim 10 , wherein determining the grouping comprises at least one of:

receiving an indication of the grouping; or

determining the grouping based on a radio network temporary identifier (RNTI).

12. The method of claim 11 , wherein the determining the grouping based on a RNTI comprises:

determining the grouping based on a transmit power control RNTI (TPC-RNTI).

13. The method of claim 11 , wherein the determining the grouping based on a RNTI comprises:

receiving a system information block (SIB) indicating a paging RNTI (P-RNTI), and

deriving the grouping based on an identifier of the UE.

14. The method of claim 10 , further comprising:

determining at least one of: a coding scheme associated with the grouping or a modulation order associated with the grouping; and

monitoring for the signaling based on the determined at least one of: the coding scheme or the modulation order.

15. The method of claim 3 , further comprising:

determining a port mapping associated with the signaling including the indication that the downlink control channel is not present in the subframe; and

monitoring for the signaling including the indication that the downlink control channel is not present in the subframe based on the determined port mapping.

16. The method of claim 3 , wherein:

the downlink control channel comprises a bundled transmission, and

the signaling including the indication that the downlink control channel is not present in the subframe is received in at least a first subframe of the bundled transmission.

17. The method of claim 16 , wherein the signaling including the indication that the downlink control channel is not present in the subframe is received in each subframe of the bundled transmission.

18. The method of claim 3 , further comprising:

performing an error check for a channel differently based on presence of the signaling including the indication that the downlink control channel is not present in the subframe in the channel.

19. The method of claim 3 , wherein a resource mapping of the signaling including the indication that the downlink control channel is not present in the subframe is based, at least in part, on at least one of: whether resources for the signaling are localized or distributed, an aggregation level of a control channel, or a port used for transmitting the signaling including the indication that the downlink control channel is not present in the subframe.

20. The method of claim 3 , wherein the low power mode includes skipping at least one of: monitoring of one or more signals or receiving of the one or more signals.

21. A method for wireless communications by a base station (BS), comprising:

determining a downlink control channel for a user equipment (UE) is not present in a subframe; and

encoding signaling, during the subframe, including an indication that the downlink control channel is not present in the subframe and the UE can enter a low power state for a remainder of the subframe; and

transmitting the signaling to the UE during subframe.

22. The method of claim 21 , wherein the signaling including the indication that the downlink control channel is not present in the subframe is transmitted in a legacy physical downlink control channel (PDCCH) region.

23. The method of claim 22 , wherein the signaling including the indication that the downlink control channel is not present in the subframe punctures the legacy PDCCH or is rate-matched around the legacy PDCCH.

24. The method of claim 21 , further comprising:

transmitting other signaling indicating a location of the signaling including the indication that the downlink control channel is not present in the subframe.

25. The method of claim 21 , further comprising:

determining a grouping associated with the signaling including the indication that the downlink control channel is not present in the subframe; and

assigning the grouping to the UE.

26. The method of claim 25 , wherein determining the grouping comprises at least one of:

determining the grouping based on a radio network temporary identifier (RNTI).

27. The method of claim 26 , wherein the determining the grouping based on a RNTI comprises:

determining the grouping based on a transmit power control RNTI (TPC-RNTI); and

scheduling UEs with a same TPC-RNTI for a same signaling indicating a location of the signaling including that the indication the downlink control channel is not present in the subframe.

28. The method of claim 26 , wherein the determining the grouping based on a RNTI comprises:

transmitting a system information block (SIB) indicating a paging RNTI (P-RNTI),

paging one or more UEs, and

transmitting signaling indicating a location of the signaling including the indication that the downlink control channel is not present in the subframe, only if at least one UE capable of receiving the signaling is paged.

29. The method of claim 21 , further comprising:

determining a port mapping associated with the signaling including the indication that the downlink control channel is not present in the subframe.

30. The method of claim 21 , wherein:

the downlink control channel comprises a bundled transmission, and

the signaling including the indication that the downlink control channel is not present in the subframe is transmitted in at least a first subframe of the bundled transmission.

31. An apparatus for wireless communications by a user equipment (UE), comprising:

means for decoding signaling, during a subframe, including an indication that a downlink control channel is not present in the subframe;

means for determining during the subframe, without decoding the downlink control channel, that the downlink control channel is not present in the subframe, wherein the determination is based on the indication in the decoded signaling; and

means for entering a low power mode for a remainder of the subframe based on the determination.

32. The apparatus of claim 31 , wherein the low power mode includes skipping at least one of: monitoring of or receiving of one or more signals.

33. An apparatus for wireless communications by a base station (BS), comprising:

means for determining a downlink control channel for a user equipment (UE) is not present in a subframe;

means for encoding signaling, during the subframe, including an indication that the downlink control channel is not present in the subframe and the UE can enter a low power state for a remainder of the subframe; and

means for transmitting the signaling to the UE during subframe.

34. An apparatus for wireless communications by a user equipment (UE), comprising:

at least one processor;

memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the UE to:

decode signaling, during a subframe, including an indication that a downlink control channel is not present in the subframe;

determine during the subframe, without decoding the downlink control channel, that the downlink control channel is not present in the subframe, wherein the determination is based on the indication in the decoded signaling; and

enter a low power mode for a remainder of the subframe based on the determination.

35. An apparatus for wireless communications by a base station (BS), comprising:

at least one processor;

memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the BS to:

determine a downlink control channel for a user equipment (UE) is not present in a subframe;

encode signaling, during the subframe, including an indication that the downlink control channel is not present in the subframe and the UE can enter a low power state for a remainder of the subframe; and

transmit the signaling to the UE during subframe.

36. A non-transitory computer-readable medium for wireless communications by a user equipment (UE), comprising code executable by at least one processor to cause the UE to:

decode signaling, during a subframe, including an indication that a downlink control channel is not present in the subframe;

determine during the subframe, without decoding the downlink control channel, that the downlink control channel is not present in the subframe, wherein the determination is based on the indication in the decoded signaling; and

enter a low power mode for a remainder of the subframe based on the determination.

37. A non-transitory computer-readable medium for wireless communications by a base station (BS), comprising code executable by at least one processor to cause the BS to:

determine a downlink control channel for a user equipment (UE) is not present in a subframe;

encode signaling, during the subframe, including an indication that the downlink control channel is not present in the subframe and the UE can enter a low power state for a remainder of the subframe; and

transmit the signaling to the UE during subframe.