Channel handoff methods in wireless broadcast systems

• US 9,554,319 B2
• Filed: 07/25/2007
• Issued: 01/24/2017
• Est. Priority Date: 09/27/2005
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Li, Linbo, Mantravadi, Ashok, Ling, Fuyun, Krishnamoorthi, Raghuraman
• Primary Examiner(s): Chriss, Andrew
• Assistant Examiner(s): Ohri, Romani
• Application Number:
  US11/828,333
• Publication Number:
  US 20080020768A1
• Time in Patent Office: 3,471 Days
• Field of Search: 370/338, 370331-337, 370/350
• US Class Current: 1/1
• CPC Class Codes: H04W 36/28 involving a plurality of connections, e.g. multi-call or multi-bearer connections
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

Systems and methodologies are described that facilitate monitoring RF channels in a wireless communication environment to determine whether one or more channels comprise a forward-link-only (FLO) signal. A receiver can receive a first RF channel with a FLO signal and can monitor other RF channels for FLO signals. Upon a determination that a monitored RF channel comprises a FLO signal, the receiver can switch between the first RF channel and the monitored RF channel, employing information on current MLC decoding status, to facilitate providing seamless reception of the FLO signal, which can be superframe synchronized between RF channels. FLO signal detection can be performed using one or more of a wide-area identification channel energy detection protocol and a wide-area overhead information symbol decoding error detection protocol.

Claims

1. A method of monitoring and switching between radio frequencies (RFs) at an access terminal in a wireless communication environment, comprising:

determining a signal quality for a current channel via which a current signal is accessed;

determining whether the determined signal quality is above a predetermined threshold value;

determining a signal quality of a neighbor channel that carries a signal that is frame synchronized with the current signal when the determined signal quality is less than or equal to the predetermined threshold value;

determining whether to perform a handoff to the neighbor channel based at least in part on the signal quality of the current channel and the signal quality of the neighbor channel;

initiating the handoff to the neighbor channel at a time when a frame is expected to be received in the current signal; and

disabling an RF monitoring for at least the current channel if the determined signal quality for the current channel is above the predetermined threshold value,

wherein the determining the signal quality of the neighbor channel comprises determining a signal strength for the neighbor channel based on a cyclic prefix (CP) correlation.

2. The method of claim 1, further comprising enabling the RF monitoring if the determined signal quality is less than or equal to the predetermined threshold value.

3. The method of claim 1, further comprising determining whether a logical channel segment failure has occurred.

4. The method of claim 3, further comprising executing an RF monitoring subroutine if the logical channel segment failure has not occurred.

5. The method of claim 4, further comprising updating an RF lookup table and executing a handoff flag generation subroutine if no logical channel segment has been detected.

6. The method of claim 5, further comprising determining whether a handoff flag, which indicates that the handoff to the neighbor channel is to be initiated, is present.

7. The method of claim 6, wherein the neighbor channel is identified by the handoff flag.

8. The method of claim 3, further comprising initiating timeout logic upon a logical channel segment failure.

9. The method of claim 8, further comprising enabling the RF monitoring and obtaining overhead information symbol (OIS) information for a logical channel segment.

10. The method of claim 9, further comprising initiating an RF monitoring subroutine.

11. The method of claim 10, further comprising updating an RF lookup table and executing a handoff flag generation subroutine if a logical channel segment failure is detected.

12. The method of claim 11, further comprising determining whether a handoff flag, which indicates that the handoff to the neighbor channel is to be initiated, is present.

13. The method of claim 12, wherein the neighbor channel is identified by the handoff flag.

14. The method of claim 1, further comprising determining whether an overhead information symbol (OIS) failure has occurred.

15. The method of claim 14, further comprising initiating a background RF monitoring protocol if the OIS failure is not detected.

16. The method of claim 14, further comprising implementing OIS failure timeout logic if the OIS failure is detected.

17. The method of claim 16, further comprising updating an RF lookup table with information related to RFs that are monitored.

18. The method of claim 17, wherein the neighbor channel comprises an optimal RF having a highest received signal strength indicator (RSSI) value according to the RF lookup table.

43. The method of claim 1 further comprising receiving a list that exclusively comprises a plurality of neighbor channels that each broadcast a substantially same contents as the current channel, wherein the list includes the neighbor channel.

19. A wireless communication apparatus, comprising:

means for measuring a signal quality for a current channel via which a current signal is accessed;

means for determining whether the measured signal quality is above a predetermined threshold value;

means for monitoring a signal quality of a neighbor channel, wherein a signal of the neighbor channel is frame synchronized with the current signal when the measured signal quality is less than or equal to the predetermined threshold value;

means for determining whether an overhead information symbol (OIS) decoding error has occurred in the current channel; and

means for performing a reacquisition protocol when the OIS decoding error is determined to have occurred in the current channel, otherwise initiating a handoff to the neighbor channel at a time when a message is expected to be received in the current signal; and

means for disabling an RF monitoring for at least the current channel if the measured signal quality for the current channel is above the predetermined threshold value,

wherein the means for monitoring the signal quality of the neighbor channel comprises means for determining a signal strength for the neighbor channel based on a cyclic prefix (CP) correlation.

20. The apparatus of claim 19, wherein the signal quality includes at least one of a received signal strength indicator (RSSI), signal to interference plus noise ratio or cyclic prefix (CP) correlation.

21. The apparatus of claim 19, further comprising means for enabling the RF monitoring if the measured signal quality is less than or equal to the predetermined threshold value.

22. The apparatus of claim 19, further comprising means for determining whether one or more multi-level coded (MLC) segments failure has occurred.

23. The apparatus of claim 22, further comprising means for executing an “

MLC successful”

radio frequency (RF) monitoring subroutine if an MLC failure has not occurred.

24. The apparatus of claim 23, further comprising means for updating an RF lookup table and generating a handoff flag that indicates an imminent handoff of an associated access terminal to the neighbor channel if one or more MLC failures is detected.

25. The apparatus of claim 24, wherein the neighbor channel is identified by the handoff flag.

26. The apparatus of claim 22, further comprising means for initiating timeout logic upon an MLC failure, means for enabling the RF monitoring, and means for obtaining overhead information symbol (OIS) information for the one or more MLC segments.

27. The apparatus of claim 26, further comprising means for initiating an RF monitoring subroutine, means for updating an RF lookup table, and means for generating a handoff flag, which indicates that an associated access terminal is to be handed off to the neighbor channel, if one or more MLC failures is detected.

28. The apparatus of claim 27, wherein the neighbor channel is indicated by the handoff flag.

29. The apparatus of claim 19, further comprising means for initiating a background radio frequency (RF) monitoring protocol if the OIS decoding error has not occurred.

30. The apparatus of claim 19, further comprising means for implementing OIS failure timeout logic if the OIS decoding error has occurred.

31. The apparatus of claim 30, further comprising means for updating an RF lookup table with information related to the monitored RFs, wherein the neighbor channel comprises an optimal RF having a highest RSSI value according to the RF lookup table.

32. A non-transitory computer-readable medium having a computer program comprising computer-executable instructions for:

measuring a signal quality for a current channel comprising a plurality of logical channels;

determining whether the measured signal quality is above a predetermined threshold value;

receiving a list that exclusively comprises a plurality of neighbor channels that each broadcast a substantially same contents as the current channel;

monitoring a signal quality of a neighbor channel of the plurality of neighbor channels that each broadcast the substantially same contents as the current channel when the measured signal quality is less than or equal to a predetermined threshold value;

determining whether a number of errors in any of the plurality of logical channels is above a threshold;

determining whether an overhead information symbol (OIS) failure has occurred;

implementing OIS failure timeout logic if the OIS failure has occurred;

performing a handoff to the neighbor channel of the plurality of neighbor channels that each broadcast the substantially same contents as the current channel when the number of errors in any of the plurality of logical channels is above the predetermined threshold value; and

disabling an RF monitoring for at least the current channel if the measured signal quality for the current channel is above the predetermined threshold value,

wherein the monitoring the signal quality of the neighbor channel comprises determining a signal strength for the neighbor channel based on a cyclic prefix (CP) correlation.

33. The computer-readable medium of claim 32, wherein the signal quality includes at least one of a received signal strength indicator (RSSI), signal to interference plus noise ratio or cyclic prefix (CP) correlation.

34. The computer-readable medium of claim 32, further comprising instructions for enabling the RF monitoring if the measured signal quality is less than or equal to the predetermined threshold value.

35. The computer-readable medium of claim 32, further comprising instructions for executing an “

MLC successful”

radio frequency (RF) monitoring subroutine when the number of errors in all of the plurality of logical channels is below the predetermined threshold value.

36. The computer-readable medium of claim 35, further comprising instructions for updating an RF lookup table and generating a handoff flag that indicates an imminent handoff of an associated access terminal to the neighbor channel when the number of errors in any of the plurality of logical channels is above the predetermined threshold value.

37. The computer-readable medium of claim 36, wherein the neighbor channel is identified by the handoff flag.

38. The computer-readable medium of claim 32, further comprising instructions for initiating timeout logic when the number of errors in any of the plurality of logical channels is above the predetermined threshold value, for enabling the RF monitoring, and for obtaining overhead information symbol (OIS) information for each of the plurality of logical channels.

39. The computer-readable medium of claim 38, further comprising instructions for initiating an RF monitoring subroutine, for updating an RF lookup table, and for generating a handoff flag, which indicates that an associated access terminal is to be handed off to the neighbor channel, when the number of errors in any of the plurality of logical channels is above the predetermined threshold value.

40. The computer-readable medium of claim 39, wherein the neighbor channel is indicated by the handoff flag.

41. The computer-readable medium of claim 32, further comprising instructions for initiating a background radio frequency (RF) monitoring protocol if the OIS failure has not occurred.

42. The computer-readable medium of claim 41, further comprising instructions for updating a radio frequency (RF) lookup table with information related to the monitored RFs, wherein the neighbor channel comprises an optimal RF having a highest received signal strength indicator (RSSI) value according to the RF lookup table.

44. An apparatus, comprising:

a memory; and

a processor coupled to the memory and configured to;

measure a signal quality for a current channel via which a current signal is accessed;

determine whether the measured signal quality is above a predetermined threshold value;

monitor a signal quality of a neighbor channel that carries a signal that is frame synchronized with the current signal when the measured signal quality is less than or equal to the predetermined threshold value;

determine whether to perform a handoff to the neighbor channel based at least in part on a decoder error rate of the current channel and the neighbor channel, wherein the decoder error rate of the neighbor channel is determined while accessing the current channel; and

initiate the handoff to the neighbor channel at a time when a message is expected to be received in the current signal; and

disable an RF monitoring for at least the current channel if the measured signal quality for the current channel is above the predetermined threshold value,

wherein the monitoring the signal quality of the neighbor channel comprises determining a signal strength for the neighbor channel based on a cyclic prefix (CP) correlation.

45. The apparatus of claim 44, wherein the signal quality includes at least one of a received signal strength indicator (RSSI), signal to interference plus noise ratio or cyclic prefix (CP) correlation.

46. The apparatus of claim 44, wherein the processor is further configured to

enable the RF monitoring if the measured signal quality is less than or equal to the predetermined threshold value.

47. The apparatus of claim 44, wherein the processor is further configured to determine whether one or more multi-level coded (MLC) segments failure has occurred.

48. The apparatus of claim 47, wherein the processor is further configured to execute an “

MLC successful”

RF monitoring subroutine if an MLC failure has not occurred.

49. The apparatus of claim 48, wherein the processor is further configured to update a radio frequency (RF) lookup table and generating a handoff flag that indicates an imminent handoff of an associated access terminal to the neighbor channel if one or more MLC failures is detected.

50. The apparatus of claim 49, wherein the neighbor channel is identified by the handoff flag.

51. The apparatus of claim 47, wherein the processor is further configured to:

initiate timeout logic upon an MLC failure, enabling radio frequency (RF) monitoring; and

obtain overhead information symbol (OIS) information for the one or more MLC segments.

52. The apparatus of claim 51, wherein the processor is further configured to initiate an RF monitoring subroutine, update an RF lookup table, and generate a handoff flag, which indicates that an associated access terminal is to be handed off to the neighbor channel, if one or more MLC failures is detected.

53. The apparatus of claim 52, wherein the neighbor channel is indicated by the handoff flag.

54. The apparatus of claim 44, wherein the processor is further configured to determine whether an overhead information symbol (OIS) failure has occurred.

55. The apparatus of claim 54, wherein the processor is further configured to initiate a background radio frequency (RF) monitoring protocol if the OIS failure has not occurred.

56. The apparatus of claim 51, wherein the processor is further configured to update a radio frequency (RF) lookup table with information related to the monitored RFs, wherein the neighbor channel comprises an optimal RF having a highest received signal strength indicator (RSSI) value according to the RF lookup table.