TIMING RESOLUTION FOR DEVICES WITH LONG SLEEP CYCLES

• US 20140301263A1
• Filed: 04/02/2014
• Published: 10/09/2014
• Est. Priority Date: 04/03/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ji, Tingfang, Banister, Brian Clarke, Gaal, Peter, Xu, Hao
• Granted Patent: US 9,503,978 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0212 managed by the network, e.g. network or access point is master and terminal is slave
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Timing resolution for user equipments (UEs) that operate using a discontinuous reception (DRX) mode that includes various sleep cycles may be addressed through selection of various alternative wake up procedures. A UE selects a wake-up procedure based on the length of the sleep cycle. The UE may use details of the sleep cycle, including a time offset or timing uncertainty associated with the sleep cycle, when selecting the wake-up procedure. The UE may select to obtain system timing information either directly from a serving cell or non-serving cell in sync with the serving cell or may select to perform either a one-step or two-step pre-wake up procedure in order to obtain the system timing. Once the UE obtains the system timing or determines a wake-up procedure, it performs timing correction before the scheduled wake-up times between the sleep cycles.

Claims

1. A method of wireless communication, comprising:

entering, by a user equipment (UE), a sleep cycle in accordance with a configuration of the UE by a wireless network;

selecting, by the UE, a wake-up procedure based on a length of the sleep cycle; and

performing a cell detection, by the UE, in accordance with the selected wake-up procedure.

2. The method of claim 1, wherein the selected wake-up procedure comprises:

waking prior to expiration of the sleep cycle; and

acquiring system timing information based on a common reference signal when the length of the sleep cycle is less than a threshold value.

3. The method of claim 2, wherein the selected wake-up procedure further comprises:

waking prior to expiration of the sleep cycle; and

acquiring the system timing information based further on a synchronization signal when the length of the sleep cycle is greater than the threshold value.

4. The method of claim 1, wherein the selected wake-up procedure comprises:

waking prior to expiration of the sleep cycle;

determining a timing correction based on network signaling;

re-entering sleep mode after the determining; and

waking from the sleep mode at a second time prior to the expiration of the sleep cycle.

5. The method of claim 2, wherein the threshold is based at least in part on a time tracking capability of the UE while in sleep mode.

6. The method of claim 2, wherein the threshold is based further on the availability at the UE of temperature compensation for time tracking.

7. The method of claim 1, wherein the selected wake-up procedure comprises:

obtaining a system timing information from one of;

a serving cell and a non-serving cell in synchronization with the serving cell of the UE.

8. The method of claim 7, wherein the system timing information is obtained from network signaling, wherein network signaling comprises one of:

a common reference signal (CRS);

a primary synchronization signal (PSS);

a secondary synchronization signal (SSS);

or

a physical broadcast channel (PBCH).

9. The method of claim 7, wherein the wake-up procedure includes one of:

a one-step wake-up procedure, comprising;

waking from the sleep cycle prior to a scheduled wake-up time; and

a two-step wake-up procedure, comprising;

waking from the sleep cycle prior to the scheduled wake-up time;

adjusting a timing of the UE using the system timing information;

re-entering a sleep mode after the adjusting; and

waking from the sleep mode at a second time prior to the scheduled wake-up time.

10. The method of claim 9, wherein the selecting further comprises:

selecting the one-step wake-up procedure when the sleep cycle is less than or equal to a threshold time or a timing uncertainty associated with the sleep cycle is greater than a pull-in range of a time tracking loop of the UE.

11. An apparatus configured for wireless communication, comprising:

means for entering, by a user equipment (UE), a sleep cycle in accordance with a configuration of the UE by a wireless network;

means for selecting, by the UE, a wake-up procedure based on a length of the sleep cycle; and

means for performing a cell detection, by the UE, in accordance with the selected wake-up procedure.

12. The apparatus of claim 11, wherein the selected wake-up procedure comprises:

means for waking prior to expiration of the sleep cycle; and

acquiring system timing information based on a common reference signal when the length of the sleep cycle is less than a threshold value.

13. The apparatus of claim 12, wherein the selected wake-up procedure comprises:

means for waking prior to expiration of the sleep cycle; and

acquiring the system timing information based further on a synchronization signal when the length of the sleep cycle is greater than the threshold value.

14. The apparatus of claim 11, wherein the selected wake-up procedure comprises:

means for waking prior to expiration of the sleep cycle;

means for determining a timing correction based on network signaling;

means for re-entering sleep mode after the means for determining; and

means for waking from the sleep mode at a second time prior to the expiration of the sleep cycle.

15. The apparatus of claim 12, wherein the threshold is based at least in part on a time tracking capability of the UE while in sleep mode.

16. The apparatus of claim 12, wherein the threshold is based further on the availability at the UE of temperature compensation for time tracking.

17. The apparatus of claim 11 wherein the wake-up procedure includes one of:

a one-step wake-up procedure, comprising;

means for waking up from the sleep cycle prior to a scheduled wake-up time; and

a two-step wake-up procedure, comprising;

means for waking up from the sleep cycle prior to the scheduled wake-up time;

means for adjusting a timing of the UE using system timing information;

means for re-entering a sleep mode after the adjusting; and

means for waking up from the sleep mode at a second time prior to the scheduled wake-up time.

18. A computer program product for wireless communications in a wireless network, comprising:

a non-transitory computer-readable medium having program code recorded thereon, the program code including;

program code for causing a computer to enter, by a user equipment (UE), a sleep cycle in accordance with a configuration of the UE by a wireless network;

program code for causing the computer to select, by the UE, a wake-up procedure based on a length of the sleep cycle; and

program code for causing the computer to perform a cell detection, by the UE, in accordance with the selected wake-up procedure.

19. The computer program product of claim 18, wherein the selected wake-up procedure comprises:

program code for causing the computer to wake prior to expiration of the sleep cycle; and

program code to acquire system timing information based on a common reference signal when the length of the sleep cycle is less than a threshold value.

20. The computer program product of claim 19, wherein the selected wake-up procedure comprises:

program code for causing the computer to wake prior to expiration of the sleep cycle; and

program code to acquire the system timing information based further on a synchronization signal when the length of the sleep cycle is greater than the threshold value.

21. The computer program product of claim 18, wherein the selected wake-up procedure comprises:

program code for causing the computer to wake prior to expiration of the sleep cycle;

program code for causing the computer to determine a timing correction based on network signaling;

program code for causing the computer to re-enter sleep mode after the program code for causing the computer to determine; and

program code for causing the computer to wake from the sleep mode at a second time prior to the expiration of the sleep cycle.

22. The computer program product of claim 19, wherein the threshold is based at least in part on a time tracking capability of the UE while in sleep mode.

23. The computer program product of claim 19, wherein the threshold is based further on the availability at the UE of temperature compensation for time tracking.

24. The computer program product of claim 18, wherein the wake-up procedure comprises:

program code for causing the computer to obtain system timing information from one of;

a serving cell and a non-serving cell in synchronization with the serving cell of the UE, wherein the system timing information is obtained from network signaling, wherein network signaling comprises one of;

a common reference signal (CRS);

a primary synchronization signal (PSS);

a secondary synchronization signal (SSS);

or

a physical broadcast channel (PBCH).

25. The computer program product of claim 24, wherein the wake-up procedure includes one of:

a one-step wake-up procedure, comprising;

program code for causing the computer to wake up from the sleep cycle prior to a scheduled wake-up time; and

a two-step wake-up procedure, comprising;

program code for causing the computer to wake up from the sleep cycle prior to the scheduled wake-up time;

program code for causing the computer to adjust a timing of the UE using the system timing information;

program code for causing the computer to re-enter a sleep mode after the program code for causing the computer to adjust; and

program code for causing the computer to wake up from the sleep mode at a second time prior to the scheduled wake-up time.

29. The apparatus of claim 25, wherein the selected wake-up procedure comprises configuration of the at least one processor:

to wake prior to expiration of the sleep cycle;

to determine a timing correction based on network signaling;

to re-enter sleep mode after the configuration of the at least one processor to determine; and

to wake from the sleep mode at a second time prior to the expiration of the sleep cycle.

26. An apparatus configured for wireless communication, the apparatus comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured;

to enter, by a user equipment (UE), a sleep cycle in accordance with a configuration of the UE by a wireless network;

to select, by the UE, a wake-up procedure based on a length of the sleep cycle; and

to perform a cell detection, by the UE, in accordance with the selected wake-up procedure.

27. The apparatus of claim 26, wherein the selected wake-up procedure comprises configuration of the at least one processor:

to wake prior to expiration of the sleep cycle; and

to acquire system timing information based on a common reference signal when the length of the sleep cycle is less than a threshold value.

28. The apparatus of claim 26, wherein the selected wake-up procedure comprises configuration of the at least one processor:

to wake prior to expiration of the sleep cycle; and

to acquire the system timing information based further on a synchronization signal when the length of the sleep cycle is greater than the threshold value.

30. The apparatus of claim 27, wherein the threshold is based at least in part on one or more of:

a time tracking capability of the UE while in sleep mode; and

the availability at the UE of temperature compensation for time tracking.