Apparatus and methods for facilitating cell reselection for higher priority layers

• US 9,615,321 B2
• Filed: 04/24/2012
• Issued: 04/04/2017
• Est. Priority Date: 06/21/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Pica, Francesco, Lee, Heechoon, Sambhwani, Sharad Deepak, Khan, Uzma
• Primary Examiner(s): Beamer, Temica M
• Assistant Examiner(s): LAM, DUNG LE
• Application Number:
  US13/454,512
• Publication Number:
  US 20120329462A1
• Time in Patent Office: 1,806 Days
• Field of Search: 4554352, 4554353, 455434, 455436, 455515, 455517
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]

Abstract

User Equipments (UEs) can be adapted to enter into a lower RRC state from a higher RRC state, and search for one or more layers of higher priority within a predetermined period of time upon entering into the lower RRC state. According to at least one aspect, this search for one or more layers of higher priority may be performed irrespective of RF quality of a current serving cell. According to at least another aspect, this search for one or more layers of higher priority may be conducted within the predetermined period of time if a wait period has elapsed since the UE camped on the current serving cell. If the wait period has not elapsed since camping on the current serving cell, the search for one or more layers of higher priority may be performed within the predetermined period of time following a duration of the wait period.

Claims

1. A user equipment, comprising:

a communications interface adapted to facilitate wireless communications;

a storage medium; and

a processing circuit coupled with the communications interface and the storage medium, the processing circuit adapted to;

camp on a current serving cell;

after starting to camp on the current serving cell and while still camping on the current serving cell, enter into a lower radio resource control (RRC) state from a higher RRC state;

upon entering into the lower RRC state from the higher RRC state, wait for a duration of a wait period since starting to camp on the current serving cell to elapse prior to searching for one or more layers of higher priority; and

search for the one or more layers of higher priority, after waiting the duration of the wait period, within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state, irrespective of a radio frequency (RF) quality of the current serving cell.

2. The user equipment of claim 1, wherein the lower RRC state comprises a stand-by state or an idle state, and the higher RRC state comprises a connected state.

3. The user equipment of claim 1, wherein the lower RRC state comprises one of a CELL_PCH state, a URA_PCH state, or an idle state, and wherein the higher RRC state is a state other than the CELL_PCH state, the URA_PCH state, and the idle state.

4. The user equipment of claim 1, wherein the RF quality of the current serving cell comprises received signal code power (RSCP) and E_c/I₀ of the current serving cell.

5. The user equipment of claim 1, wherein the wait period is equal to a delay period during which the processing circuit is adapted to delay before conducting a cell reselection procedure after camping on the current serving cell.

6. A method operational on a user equipment, comprising:

camping on a current serving cell;

after starting to camp on the current serving cell and while still camping on the current serving cell, entering into a lower radio resource control (RRC) state from a higher RRC state;

upon entering into the lower RRC state from the higher RRC state, waiting for a duration of a wait period since starting to camp on the current serving cell to elapse prior to searching for one or more layers of higher priority; and

searching for the one or more layers of higher priority, after waiting the duration of the wait period, within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state, regardless of a radio frequency (RF) quality of the current serving cell.

7. The method of claim 6, wherein entering into a lower RRC state from a higher RRC state comprises:

entering into a stand-by state or an idle state from a connected state.

8. The method of claim 6, wherein entering into a lower RRC state from a higher RRC state comprises:

entering into one of a CELL_PCH state, a URA_PCH state, or an idle state from an RRC state other than the CELL_PCH state, the URA_PCH state, and the idle state.

9. The method of claim 6, wherein searching for one or more layers of higher priority after waiting the duration of the wait period, regardless of an RF quality of a current serving cell comprises:

searching for the one or more layers of higher priority within a first DRX cycle after waiting the duration of the wait period, regardless of respective values for received signal code power (RSCP) and for E_c/I₀ of the current serving cell.

10. The method of claim 6, wherein waiting for the duration of the wait period since starting to camp on the current serving cell to elapse comprises:

waiting for a period of time at least substantially equal to a period of time during which no cell reselection procedure is conducted after camping on the current serving cell.

29. The method of claim 6, wherein searching for one or more layers of higher priority within a first DRX cycle after entering into the lower RRC state from the higher RRC state comprises searching for the one or more layers of higher priority within the first DRX cycle after entering into the lower RRC state from the higher RRC state, if the received signal code power (RSCP) value of the current serving cell is less than or equal to a first threshold value or if the E_c/I₀ value of the current serving cell is less than or equal to a second threshold value.

11. A user equipment, comprising:

means for camping on a current serving cell;

means for entering, after starting to camp on the current serving cell and while still camping on the current serving cell, into a lower radio resource control (RRC) state from a higher RRC state;

means for waiting, upon entering into the lower RRC state from the higher RRC state, for a duration of a wait period since starting to camp on the current serving cell to elapse prior to searching for one or more layers of higher priority; and

means for searching for the one or more layers of higher priority, after waiting the duration of the wait period, within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state, irrespective of a radio frequency (RF) quality of the current serving cell.

12. The user equipment of claim 11, wherein the lower RRC state includes a stand-by state or an idle state, and the higher RRC state includes a connected state.

13. The user equipment of claim 11, wherein the lower RRC state comprises one of a CELL_PCH state, a URA_PCH state, or an idle state, and wherein the higher RRC state is a state other than the CELL_PCH state, the URA_PCH state, and the idle state.

14. A non-transitory computer-readable medium comprising code executable by a processor on a user equipment, comprising:

code for camping on a current serving cell;

code for entering, after starting to camp on the current serving cell and while still camping on the current serving cell, into a lower radio resource control (RRC) state from a higher RRC state;

code for waiting, upon entering into the lower RRC state from the higher RRC state, for a duration of a wait period since starting to camp on the current serving cell to elapse before searching for one or more layers of higher priority; and

code for searching for the one or more layers of higher priority, after waiting the duration of the wait period, within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state, independent of a radio frequency (RF) quality of the current serving cell.

15. The non-transitory machine-readable medium of claim 14, wherein the lower RRC state includes a stand-by state or an idle state, and the higher RRC state includes a connected state.

16. The non-transitory machine-readable medium of claim 14, wherein the lower RRC state comprises one of a CELL_PCH state, a URA_PCH state, or an idle state, and wherein the higher RRC state is a state other than the CELL_PCH state, the URA_PCH state, and the idle state.

17. A user equipment, comprising:

a communications interface adapted to facilitate wireless communications;

a storage medium; and

a processing circuit coupled to the communications interface and the storage medium, the processing circuit adapted to;

camp on a current serving cell;

after starting to camp on the current serving cell and while still camping on the current serving cell, enter into a lower radio resource control (RRC) state from a higher RRC state;

determine whether a wait period has elapsed since starting to camp on the current serving cell;

if the wait period has elapsed since starting to camp on the current serving cell, search for one or more layers of higher priority within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state; and

if the wait period has not elapsed since starting to camp on the current serving cell, search for one or more layers of higher priority within a second DRX cycle following a duration of the wait period.

18. The user equipment of claim 17, wherein the lower RRC state comprises one of a CELL_PCH state, a URA_PCH state, or an idle state, and wherein the higher RRC state is a state other than the CELL_PCH state, the URA_PCH state, and the idle state.

19. The user equipment of claim 17, wherein the wait period is equal to a delay period during which the processing circuit is adapted to abstain from cell reselection after camping on the current serving cell.

20. The user equipment of claim 17, wherein, if the wait period has not elapsed since starting to camp on the current serving cell, the processing circuit is adapted to:

search for one or more layers of higher priority within the second DRX cycle plus the wait period.

21. The user equipment of claim 17, wherein, if the wait period has not elapsed since starting to camp on the current serving cell, the processing circuit is adapted to:

search for one or more layers of higher priority within the second DRX cycle after the wait period has elapsed since camping on the current serving cell.

22. A method operational on a user equipment, comprising:

camping on a current serving cell;

after starting to camp on the current serving cell and while still camping on the current serving cell, entering into a lower radio resource control (RRC) state from a higher RRC state;

determining whether a wait period has elapsed since starting to camp on the current serving cell;

if the wait period has elapsed since starting to camp on the current serving cell, searching for one or more layers of higher priority within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state; and

if the wait period has not elapsed since starting to camp on the current serving cell, searching for one or more layers of higher priority within a second DRX cycle following a duration of the wait period.

23. The method of claim 22, wherein entering into a lower RRC state from a higher RRC state comprises:

entering into one of a CELL_PCH state, a URA_PCH state, or an idle state from an RRC state other than the CELL_PCH state, the URA_PCH state, and the idle state.

24. The method of claim 22, wherein searching for one or more layers of higher priority within a second DRX cycle following a duration of the wait period comprises:

searching for one or more layers of higher priority within the second DRX cycle following a duration of delay period during which no cell reselection is performed after camping on the current serving cell.

25. The method of claim 22, wherein searching for one or more layers of higher priority within a second DRX cycle following a duration of the wait period comprises:

searching for one or more layers of higher priority within the second DRX cycle plus the duration of the wait period.

26. The method of claim 22, wherein searching for one or more layers of higher priority within a second DRX cycle following a duration of the wait period comprises:

searching for one or more layers of higher priority within the second DRX cycle after the wait period has elapsed since starting to camp on the current serving cell.

27. A user equipment, comprising:

means for camping on a current serving cell;

means for entering, after starting to camp on the current serving cell and while still camping on the current serving cell, into a lower radio resource control (RRC) state from a higher RRC state;

means for determining whether a wait period has elapsed since starting to camp on the current serving cell;

means for searching for one or more layers of higher priority within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state, if the wait period has elapsed since starting to camp on the current serving cell; and

means for searching for one or more layers of higher priority within a second DRX cycle following a duration of the wait period, if the wait period has not elapsed since starting to camp on the current serving cell.

28. A non-transitory machine-readable medium comprising instructions operational on an user equipment, which when executed by a processor cause the processor to:

camp on a current serving cell;

after starting to camp on the current serving cell and while still camping on the current serving cell, enter into a lower radio resource control (RRC) state from a higher RRC state;

determining whether a wait period has elapsed since starting to camp on the current serving cell;

if the wait period has elapsed since starting to camp on the current serving cell, search for one or more layers of higher priority within a first discontinuous reception (DRX) cycle after entering into the lower RRC state from the higher RRC state; and

if the wait period has not elapsed since starting to camp on the current serving cell, search for one or more layers of higher priority within a second DRX cycle following a duration of the wait period.