Power saving signals in wireless communication
Systems, methods, and devices for addressing power savings signals in wireless communication. A wireless transmit receive unit (WTRU) may monitor for an energy saving signal (ESS) while the WTRU is asleep (e.g., prior to a discontinuous reception (DRX) ON duration that includes one or more search spaces). The WTRU may measure the energy of the ESS. If the ESS is below a threshold, the WTRU fallback to a default operation or continue in a current operating mode (e.g., remain asleep to save power). If the ESS is above a threshold, the ESS may be received using a coverage enhancement (CE) level based on a parameter associated with a search space. The parameter may be the highest aggregation level of the one or more search spaces.
1. A wireless transmit/receive unit (WTRU) comprising a processor and memory, the processor and memory configured to:
receive a wakeup signal (WUS) during a period of time prior to a start of discontinuous reception (DRX) active time when performing DRX in accordance with a long DRX cycle length;
start an on-duration timer when performing DRX in accordance with the long DRX cycle length in response to receiving the WUS, wherein the WUS indicates that the WTRU is to monitor for physical downlink control channel (PDCCH) transmissions during DRX active time when the WTRU is performing DRX in accordance with the long DRX cycle length; and
start the on-duration timer when the WTRU is performing DRX in accordance with a short DRX cycle length, wherein the WTRU is configured to start the on-duration timer when performing DRX in accordance with the short DRX cycle length irrespective of whether the WUS is received during the period of time prior to the start of DRX active time when performing DRX in accordance with the short DRX cycle length, and wherein the long DRX cycle length is longer than the short DRX cycle length.
2. The WTRU of claim 1 , further configured to use the WUS to determine when to monitor for PDCCH transmissions based on a configuration.
3. The WTRU of claim 1 , wherein DRX active time comprises one or more of:
time(s) during which the on-duration timer is running;
time(s) during which an inactivity timer is running;
time(s) during which a retransmission timer is running; or
time(s) during which a random-access contention resolution timer is running.
4. The WTRU of claim 1 , wherein the WUS comprises a reduced PDCCH monitoring signal associated with reducing a periodicity of monitoring for PDCCH transmissions.
5. The WTRU of claim 1 , further configured to skip monitoring for PDCCH transmissions if the WUS is not received when performing DRX in accordance with the long DRX cycle length.
6. The WTRU of claim 1 , wherein the WUS is associated with a PDCCH transmission received prior to the WTRU operating in DRX active time.
7. The WTRU of claim 1 , wherein the WUS corresponds to a PDCCH transmission comprising downlink control information (DCI) with a cyclic redundancy check (CRC) that is scrambled with power savings radio network temporary identifier (PS-RNTI).
8. The WTRU of claim 1 , wherein the WUS is indicated using a payload of a downlink control information (DCI) comprised in a PDCCH transmission.
9. The WTRU of claim 1 , further configured to monitor for PDCCH transmissions for detection of the WUS in one or more search space sets.
10. A method of saving power for a wireless transmit/receive unit (WTRU), the method comprising:
receiving a wakeup signal (WUS) during a period of time prior to a start of discontinuous reception (DRX) active time when performing DRX in accordance with a long DRX cycle length;
starting an on-duration timer when performing DRX in accordance with the long DRX cycle length in response to receiving the WUS, wherein the WUS indicates that the WTRU is to monitor for physical downlink control channel (PDCCH) transmissions during DRX active time when the WTRU is performing DRX in accordance with the long DRX cycle length; and
starting the on-duration timer when the WTRU is performing DRX in accordance with a short DRX cycle length, wherein the WTRU is configured to start the on-duration timer when performing DRX in accordance with the short DRX cycle length irrespective of whether the WUS is received during the period of time prior to the start of DRX active time when performing DRX in accordance with the short DRX cycle length, and wherein the long DRX cycle length is longer than the short DRX cycle length.
11. The method of claim 10 , further comprising using the WUS to determine when to monitor for PDCCH transmissions based on a configuration.
12. The method of claim 10 , wherein DRX active time comprises one or more of:
time(s) during which the on-duration timer is running;
time(s) during which an inactivity timer is running;
time(s) during which a retransmission timer is running; or
time(s) during which a random-access contention resolution timer is running.
13. The method of claim 10 , wherein the WUS comprises a reduced PDCCH monitoring signal associated with reducing a periodicity of monitoring for PDCCH transmissions.
14. The method of claim 10 , further comprising skipping monitoring for PDCCH transmissions if the WUS is not received when performing DRX in accordance with the long DRX cycle length.
15. The method of claim 10 , wherein the WUS is associated with a PDCCH transmission received prior to the WTRU operating in DRX active time.
16. The method of claim 10 , wherein the WUS corresponds to a PDCCH transmission comprising downlink control information (DCI) with a cyclic redundancy check (CRC) that is scrambled with power savings radio network temporary identifier (PS-RNTI).
17. The method of claim 10 , wherein the WUS is indicated using a payload of a downlink control information (DCI) comprised in a PDCCH transmission.
18. The method of claim 10 , further comprising monitoring for PDCCH transmissions for detection of the WUS in one or more search space sets.