Battery efficient method to search for preferred femtocell

• US 9,386,431 B2
• Filed: 07/31/2009
• Issued: 07/05/2016
• Est. Priority Date: 08/05/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Jen Mei, Yavuz, Mehmet, Nanda, Sanjiv, Deshpande, Manoj M., Pica, Fracesco
• Primary Examiner(s): Sciacca, Scott M
• Application Number:
  US12/533,651
• Publication Number:
  US 20100035601A1
• Time in Patent Office: 2,531 Days
• Field of Search: 370/331, 370/332
• US Class Current: 1/1
• CPC Class Codes: H04W 4/20 Services signaling; Auxiliary data signalling, i.e. transmitting data via a non-traffic channel
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Mobile user equipment (MUE) can be enabled to search for and camp on a preferred node, such as a home base node (HBN), in a battery-efficient manner even when currently camped on another node, such as a macro base node (MBN). When the MBN provides good channel quality, slow rate background intra- and inter-frequency searches can discover the preferred HBN that would otherwise not be discovered or would consume excessive power with continual searching. When channel quality is fair, slow rate background inter-frequency searches can result in timely switching to the preferred HBN. Location hints that indicate proximity of the preferred HBN can be used to trigger slow rate background searches. Neighboring cell searching of neighbor cell listing (NCL) when in channel quality is fair or poor are maintained to prepare for call reselections to available node.

Claims

1. A method for reliable and power-efficient discovery of a preferred node, comprising:

measuring signal quality of a wireless channel transmitted by a serving node;

determining the signal quality to be above a threshold, wherein being below the threshold indicates a need to prepare for cell reselection to another neighboring node;

periodically performing measurements for one or more neighboring nodes; and

periodically performing measurements for the preferred node, distinct from and higher priority than the serving node and the one or more neighboring nodes, at a slower repetition rate than the measurements for the one or more neighboring nodes in response to the signal quality being above the threshold.

2. The method of claim 1, further comprising determining the signal quality to indicate a good channel above the threshold that would otherwise trigger intra-frequency searching.

3. The method of claim 1, further comprising determining the signal quality to indicate a fair channel above the threshold that would otherwise trigger inter-frequency searching.

4. The method of claim 1, further comprising performing measurements for a preferred closed subscription node.

5. The method of claim 1, further comprising performing measurements for a femtocell.

6. The method of claim 5, further comprising performing measurements for a home base node.

7. The method of claim 1, further comprising enabling the slower repetition rate measurements for the preferred node in response to a determination that user equipment has predefined a preferred node.

8. The method of claim 1, further comprising:

performing synchronization and measurement for transmissions from the serving node during each discontinuous reception (DRX) cycle; and

performing the slower repetition rate at multiples of the discontinuous reception (DRX) cycle.

9. The method of claim 1, further comprising:

accessing information indicative of a location of a mobile device;

determining proximity to the preferred node; and

enabling slower repetition rate measurements for the preferred node in response to the proximity being closer than a coverage area threshold.

10. The method of claim 9, further comprising:

determining the location based upon a positioning system; and

accessing a geographic location for the preferred node.

11. The method of claim 9, further comprising associating a location of the preferred node as proximate to a coverage area of a macro base node.

12. The method of claim 9, further comprising:

associating a broadcast beacon with the preferred node; and

initiating periodic measurements for the preferred node at the slower repetition rate in response to detecting the broadcast beacon.

13. The method of claim 1, further comprising receiving broadcast information from a node identifying the one or more neighboring nodes.

14. The method of claim 1, further comprising receiving self-identifying broadcast information from the preferred node.

15. The method of claim 1, further comprising:

receiving a scrambling code by broadcast for demodulating a synchronization signal from a node; and

periodically performing the measurements for the preferred node using the scrambling code.

16. The method of claim 15, further comprising receiving a plurality of scrambling codes for respective neighboring nodes from a serving node.

17. The method of claim 15, further comprising receiving the scrambling code from a non-serving preferred node that transmits using the scrambling code.

18. The method of claim 1, further comprising discontinuing periodically performing the measurements for the preferred node at the slower repetition rate than the measurements for the one or more neighboring nodes in response to camping on the preferred node.

19. The method of claim 1, wherein the serving node is a macro base node, the one or more neighboring nodes are one or more other macro base nodes, and the preferred node is a femtocell or other home base node.

20. The method of claim 1, further comprising refraining from periodically performing the measurements for the preferred node in response to the signal quality being above a second threshold higher than a first threshold.

21. A non-transitory computer-readable medium comprising instructions, which, when executed by a processor, cause the processor to perform operations for reliable and power-efficient discovery of a preferred node, the instructions comprising:

a first set of instructions for causing a computer to measure signal quality of a wireless channel transmitted by a serving node;

a second set of instructions for causing the computer to determine the signal quality to be above a threshold, wherein being below the threshold indicates a need to prepare for cell reselection to another neighboring node;

a third set of instructions for causing the computer to periodically perform measurements for one or more neighboring nodes; and

a fourth set of instructions for causing the computer to periodically perform measurements for the preferred node, distinct from and higher priority than the serving node and the one or more neighboring nodes, at a slower repetition rate than the measurements for the one or more neighboring nodes in response to the signal quality being above the threshold.

22. An apparatus for reliable and power-efficient discovery of a preferred node, comprising:

means for measuring signal quality of a wireless channel transmitted by a serving node;

means for determining the signal quality to be above a threshold, wherein being below the threshold indicates a need to prepare for cell reselection to another neighboring node;

means for periodically performing measurements for the one or more neighboring nodes; and

means for periodically performing measurements for the a preferred node, distinct from and higher priority than the serving node and the one or more neighboring nodes, at a slower repetition rate than the measurements for the one or more neighboring nodes in response to the signal quality being above the threshold.

23. An apparatus for reliable and power-efficient discovery of a preferred node, comprising:

a receiver configured to measure signal quality of a wireless channel transmitted by a serving node;

at least one processor; and

at least one memory coupled to the at least one processor, the at least one processor and the at least one memory being configured to;

determine the signal quality to be above a threshold, wherein being below the threshold indicates a need to prepare for cell reselection to another neighboring node,

cause the receiver to periodically perform measurements for one or more neighboring nodes, and

cause the receiver to periodically perform measurements for the preferred node, distinct from and higher priority than the serving node and the one or more neighboring nodes, at a slower repetition rate than the measurements for the one or more neighboring nodes in response to the signal quality being above the threshold.

24. The apparatus of claim 23, the at least one processor and the at least one memory being configured to determine the signal quality to indicate a good channel above the threshold that would otherwise trigger intra-frequency searching.

25. The apparatus of claim 23, the at least one processor and the at least one memory being configured to determine the signal quality to indicate a fair channel above the threshold that would otherwise trigger inter-frequency searching.

26. The apparatus of claim 23, wherein the receiver is further configured to perform measurements for a preferred closed subscription node.

27. The apparatus of claim 23, wherein the receiver is further configured to perform measurements for a femtocell.

28. The apparatus of claim 27, wherein the receiver is further configured to perform measurements for a home base node.

29. The apparatus of claim 23, the at least one processor and the at least one memory being configured to enable the slower repetition rate measurements for the preferred node in response to a determination that user equipment has predefined a preferred node.

30. The apparatus of claim 23, the at least one processor and the at least one memory being configured to perform synchronization and measurement for transmissions from the serving node during each discontinuous reception (DRX) cycle, and for performing the slower repetition rate at multiples of the discontinuous reception (DRX) cycle.

31. The apparatus of claim 23, the at least one processor and the at least one memory being configured to access information indicative of a location of a mobile device, for determining proximity to the preferred node, and for enabling slower repetition rate measurements for the preferred node in response to the proximity being closer than a coverage area threshold.

32. The apparatus of claim 31, the at least one processor and the at least one memory being configured to determine the location based upon a positioning system, and for accessing a geographic location for the preferred node.

33. The apparatus of claim 31, the at least one processor and the at least one memory being configured to associate a location of the preferred node as proximate to a coverage area of a macro base node.

34. The apparatus of claim 31, the at least one processor and the at least one memory being configured to associate a broadcast beacon with the preferred node, and for initiating periodic measurements for the preferred node at the slower repetition rate in response to the receiver detecting the broadcast beacon.

35. The apparatus of claim 23, the receiver being further configured to receive broadcast information from a node identifying the one or more neighboring nodes.

36. The apparatus of claim 23, the receiver being further configured to receive self-identifying broadcast information from the preferred node.

37. The apparatus of claim 23, the receiver being further configured to receive a scrambling code by broadcast for demodulating a synchronization signal from a node, and to periodically perform the measurements for the preferred node using the scrambling code.

38. The apparatus of claim 37, the receiver being further configured to receive a plurality of scrambling codes for respective neighboring nodes from a serving node.

39. The apparatus of claim 37, the receiver being further configured to receive the scrambling code from a non-serving preferred node that transmits using the scrambling code.

40. The apparatus of claim 23, the at least one processor and the at least one memory being configured to discontinue periodically performing the measurements for the preferred node at the slower repetition rate than the measurements for the one or more neighboring nodes in response to camping on the preferred node.

41. A method for facilitating reliable and power-efficient discovery of a preferred node, comprising:

serving a mobile device as a serving node by transmitting and receiving wireless data packet communication; and

facilitating discovery by the mobile device of the preferred node, distinct from and higher priority than the serving node, by broadcasting a scrambling code used by the preferred node to the mobile device,

wherein the mobile device periodically performs measurements for the preferred node at a slower repetition rate than measurements for one or more neighboring nodes in response to signal quality being above a threshold.

42. The method of claim 41, further comprising:

maintaining a neighbor list for nodes within a coverage area, wherein the preferred node is one of the nodes; and

broadcasting scrambling codes for the nodes within the coverage area.

43. The method of claim 41, further comprising broadcasting the scrambling code by the preferred node for facilitating discovery by the mobile device.

44. The method of claim 41, further comprising scheduling a served mobile device for a discontinuous reception (DRX) cycle for performing synchronization and measurement for transmissions from the serving node and the one or more neighboring nodes and for periodically performing the measurements for the preferred node at the slower repetition rate than the measurements for the one or more neighboring nodes in response to the signal quality being above the threshold.

45. The method of claim 41, further comprising transmitting information related to location enabling the mobile device to selectively perform the measurements for the preferred node at the slower repetition rate.

46. A non-transitory computer-readable medium comprising instructions, which, when executed by a processor, cause the processor to perform operations for facilitating reliable and power-efficient discovery of a preferred node, the instructions comprising:

a first set of instructions for causing a computer to serve a mobile device as a serving node by transmitting and receiving wireless data packet communication; and

a second set of instructions for causing the computer to facilitate discovery by the mobile device of the preferred node, distinct from and higher priority than the serving node, by broadcasting a scrambling code used by the preferred node to the mobile device,

wherein the mobile device periodically performs measurements for the preferred node at a slower repetition rate than measurements for one or more neighboring nodes in response to signal quality being above a threshold.

47. An apparatus for facilitating reliable and power-efficient discovery of a preferred node, comprising:

means for serving a mobile device as a serving node by transmitting and receiving wireless data packet communication; and

means for facilitating discovery by the mobile device of the preferred node, distinct from and higher priority than the serving node, by broadcasting a scrambling code used by the preferred node to the mobile device,

wherein the mobile device periodically performs measurements for the preferred node at a slower repetition rate than measurements for one or more neighboring nodes in response to signal quality being above a threshold.

48. An apparatus for facilitating reliable and power-efficient discovery of a preferred node, comprising:

a receiver configured to receive wireless data packet communication service from a mobile device as a serving node;

at least one processor; and

at least one memory coupled to the at least one processor, the at least one processor and the at least one memory being configured to access a scrambling code used by the preferred node, distinct from and higher priority than the serving node; and

a transmitter configured to broadcast the scrambling code to the mobile device facilitating discovery by the mobile device of a the preferred node,

wherein the mobile device periodically performs measurements for the preferred node at a slower repetition rate than measurements for one or more neighboring nodes in response to signal quality being above a threshold.

49. The apparatus of claim 48, the at least one processor and the at least one memory being configured to maintain a neighbor list for nodes within a coverage area, wherein the preferred node is one of the nodes;

and

the transmitter is further for broadcasting scrambling codes for the nodes within the coverage area.

50. The apparatus of claim 48, the transmitter being further configured to broadcast the scrambling code by the preferred node for facilitating discovery by the mobile device.

51. The apparatus of claim 48, the at least one processor and the at least one memory being configured to schedule a served mobile device for a discontinuous reception (DRX) cycle for performing synchronization and measurement for transmissions from the serving node and the one or more neighboring nodes and to periodically perform the measurements for the preferred node at the slower repetition rate than the measurements for the one or more neighboring nodes in response to the signal quality being above the threshold.

52. The apparatus of claim 48, the transmitter being further configured to transmit information related to location enabling the mobile device to selectively perform the measurements for the preferred node at the slower repetition rate.