Enhanced machine type communications quick idle transition after connection release

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

determining, based on an indication received in a narrowband signal on a narrowband region of a bandwidth comprising a plurality of narrowband regions, whether to wait for a delay period, determined based on a configuration received from a network entity, before releasing a radio resource control (RRC) connection; and

releasing the RRC connection at a time in accordance with the determination;

wherein:

the narrowband signal comprises a command to release the RRC connection;

the indication comprises a set polling bit in a radio link control (RLC) layer portion of the narrowband signal;

the determination is to wait for the delay period, based on the polling bit; and

the method further comprises:

sending a hybrid automatic retransmission request (HARQ) acknowledgment (ACK) of the narrowband signal prior to releasing the RRC connection;

receiving a first downlink control information (DCI) comprising an N 0 grant having a new data indicator (NDI) that is not toggled; and

sending a layer 2 (L2) ACK of the narrowband signal, via transmission resources indicated in the N 0 grant, prior to releasing the RRC connection.

2. The method of claim 1 , wherein the indication is a first indication, the method further comprising:

receiving a second indication comprising an unset polling bit in the RLC layer portion of the narrowband signal; and

determining to not wait for the delay period.

3. The method of claim 2 , further comprising:

powering down one or more radio components of the UE subsequent to releasing the RRC connection.

4. The method of claim 1 , further comprising:

receiving a second DCI comprising a request for a retransmission of the L2 ACK; and

retransmitting the L2 ACK prior to releasing the RRC connection.

5. The method of claim 1 , further comprising:

determining, based on a coverage level of the UE, a length of the delay period.

6. The method of claim 5 , wherein the determining the length of the delay period comprises:

determining a length of a narrowband physical downlink control channel (NPDCCH) period based on a number of repetitions determined based on the coverage level;

determining a number of the NPDCCH periods based on the coverage level; and

calculating the delay period as the determined number of the NPDCCH periods.

7. The method of claim 6 , wherein determining the number of the NPDCCH periods comprises selecting the number from a table of coverage levels, based on the coverage level.

8. The method of claim 1 , further comprising:

receiving a second DCI comprising another NO grant having an NDI that is toggled; and

making a new determination, to not wait for the delay period before releasing the RRC connection, in response to receiving the second DCI.

9. An apparatus for wireless communications, comprising:

a processor configured to:

determine, based on an indication received in a narrowband signal on a narrowband region of a bandwidth comprising a plurality of narrowband regions, whether to wait for a delay period, determined based on a configuration received from a network entity, before causing the apparatus to release a radio resource control (RRC) connection; and

cause the apparatus to release the RRC connection at a time in accordance with the determination; and

a memory coupled with the processor

wherein:

the narrowband signal comprises a command to release the RRC connection;

the indication comprises a set polling bit in a radio link control (RLC) layer portion of the narrowband signal; and

the processor is further configured to:

determine to wait for the delay period, based on the polling bit;

cause the apparatus to send a hybrid automatic retransmission request (HARQ) acknowledgment (ACK) of the narrowband signal prior to releasing the RRC connection;

cause the apparatus to receive a first downlink control information (DCI) comprising an NO grant having a new data indicator (NDI) that is not toggled; and

cause the apparatus to send a layer 2 (L2) ACK of the narrowband signal, via transmission resources indicated in the NO grant, prior to releasing the RRC connection.

10. The apparatus of claim 9 , wherein the indication is a first indication, and the processor is configured to:

receive a second indication comprising an unset polling bit in the RLC layer portion of the narrowband signal;

determine to not wait for the delay period.

11. The apparatus of claim 10 , wherein the processor is configured to:

cause the apparatus to power down one or more radio components of the apparatus subsequent to releasing the RRC connection.

12. The apparatus of claim 9 , wherein the processor is further configured to:

cause the apparatus to receive a second DCI comprising a request for a retransmission of the L2 ACK; and

cause the apparatus to retransmit the L2 ACK prior to releasing the RRC connection.

13. The apparatus of claim 9 , wherein the processor is further configured to:

determine, based on a coverage level of the UE, a length of the delay period.

14. The apparatus of claim 13 , wherein the determining the length of the delay period comprises:

determining a length of a narrowband physical downlink control channel (NPDCCH) period based on a number of repetitions determined based on the coverage level;

determining a number of the NPDCCH periods based on the coverage level; and

calculating the delay period as the determined number of the NPDCCH periods.

15. The apparatus of claim 13 , wherein the processor is further configured to:

cause the apparatus to receive a second DCI comprising another NO grant having an NDI that is toggled; and

make a new determination, to not wait for the delay period before releasing the RRC connection, in response to receiving the second DCI.

16. The apparatus of claim 14 , wherein the processor is configured to determine the number of the NPDCCH periods by selecting the number from a table of coverage levels, based on the coverage level.

17. An apparatus for wireless communications, comprising:

means for determining, based on an indication received in a narrowband signal on a narrowband region of a bandwidth comprising a plurality of narrowband regions, whether to wait for a delay period, determined based on a configuration received from a network entity, before releasing a radio resource control (RRC) connection; and

means for releasing the RRC connection at a time in accordance with the determination;

wherein:

the narrowband signal comprises a command to release the RRC connection;

the indication comprises a set polling bit in a radio link control (RLC) layer portion of the narrowband signal;

the determination is to wait for the delay period, based on the polling bit; and

the apparatus further comprises:

means for sending a hybrid automatic retransmission request (HARQ) acknowledgment (ACK) of the narrowband signal prior to releasing the RRC connection;

means for receiving a first downlink control information (DCI) comprising an NO grant having a new data indicator (NDI) that is not toggled; and

means for sending a layer 2 (L2) ACK of the narrowband signal, via transmission resources indicated in the NO grant, prior to releasing the RRC connection.

18. A computer-readable medium for wireless communications including instructions, the instructions, when executed by a processor, cause the processor to perform operations comprising:

determining, based on an indication received in a narrowband signal on a narrowband region of a bandwidth comprising a plurality of narrowband regions, whether to wait for a delay period, determined based on a configuration received from a network entity, before releasing a radio resource control (RRC) connection; and

releasing the RRC connection at a time in accordance with the determination;

wherein:

the narrowband signal comprises a command to release the RRC connection;

the indication comprises a set polling bit in a radio link control (RLC) layer portion of the narrowband signal;

the determination is to wait for the delay period, based on the polling bit; and

the operations further comprise:

sending a hybrid automatic retransmission request (HARQ) acknowledgment (ACK) of the narrowband signal prior to releasing the RRC connection;

receiving a first downlink control information (DCI) comprising an NO grant having a new data indicator (NDI) that is not toggled; and

sending a layer 2 (L2) ACK of the narrowband signal, via transmission resources indicated in the NO grant, prior to releasing the RRC connection.