RF channel switching in broadcast OFDM systems

• US 8,705,370 B2
• Filed: 03/11/2010
• Issued: 04/22/2014
• Est. Priority Date: 09/27/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Li, Linbo, Mantravadi, Ashok, Ling, Fuyun, Krishnamoorthi, Raghuraman
• Primary Examiner(s): Nguyen, Hanh N
• Application Number:
  US12/722,308
• Publication Number:
  US 20100165851A1
• Time in Patent Office: 1,503 Days
• Field of Search: 370/338, 370/241, 370/395.21, 370/280, 370/329, 370/390, 370/247, 370/251, 370/294, 370/314
• US Class Current: 370/241
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

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 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 detecting broadcast services in a radio frequency (RF) in a wireless communication environment, comprising:

determining whether a monitoring condition exists while accessing a service through a current RF channel comprising a first signal; and

monitoring at least one new RF channel and analyzing a second signal received through the at least one new RF channel to determine whether the service is available on the at least one new RF channel,

wherein the analyzing is based in part on whether a pilot symbol is detected in the second signal within a period of time during which the pilot symbol is expected to be received in the current RF channel.

2. The method of claim 1, wherein the monitoring condition is at least one of a loss-of-lock event or an application-initiated monitoring event.

3. The method of claim 1, wherein background monitoring of the at least one new RF channel is performed according to a predetermined schedule that is at least one of continuous and periodic.

4. The method of claim 1, wherein the pilot symbol comprises a time-division multiplexed (TDM) pilot symbol.

5. The method of claim 4, further comprising initiating a counter to zero to detect the TDM pilot symbol.

6. The method of claim 5, further comprising incrementing the counter.

7. The method of claim 6, further comprising determining whether the TDM pilot symbol has been detected.

8. A method of detecting broadcast services in a radio frequency (RF) in a wireless communication environment, comprising:

determining whether a monitoring condition exists while accessing a service through a current RF channel comprising a first signal;

monitoring at least one new RF channel and analyzing a second signal received through the at least one new RF channel to determine whether the service is available on the at least one new RF channel, wherein the analyzing is based in part on whether a pilot symbol is detected in the second signal within a period of time, wherein the pilot symbol comprises a time-division multiplexed (TDM) pilot symbol;

initiating a counter to zero to detect the TDM pilot symbol;

incrementing the counter;

determining whether the TDM pilot symbol has been detected; and

incrementing the counter if the TDM pilot symbol is not detected and maintaining the counter at a current value if the TDM pilot symbol is detected.

9. A method of detecting broadcast services in a radio frequency (RF) in a wireless communication environment, comprising:

determining whether a monitoring condition exists while accessing a service through a current RF channel comprising a first signal;

monitoring at least one new RF channel and analyzing a second signal received through the at least one new RF channel to determine whether the service is available on the at least one new RF channel, wherein the analyzing is based in part on whether a pilot symbol is detected in the second signal within a period of time, wherein the pilot symbol comprises a time-division multiplexed (TDM) pilot symbol;

initiating a counter to zero to detect the TDM pilot symbol;

incrementing the counter;

determining whether the TDM pilot symbol has been detected; and

determining whether a counter value is greater than a value associated with the TDM pilot symbol exclusively when the TDM pilot symbol is detected.

10. The method of claim 9, further comprising concluding that the service is not available on the new RF channel exclusively when the counter value is greater than the value associated with the TDM pilot symbol.

11. The method of claim 9, further comprising determining whether a late-detection attempt is to be initiated if the counter value is not greater than the value associated with the TDM pilot symbol.

12. The method of claim 11, further comprising reincrementing the counter and attempting to detect the TDM pilot symbol if a late-detection attempt is initiated.

13. The method of claim 11, further comprising evaluating an energy level associated with a wide area identification (WID) channel if no late-detection attempt is initiated and comparing the WID channel energy level to a predetermined threshold.

14. The method of claim 13, further comprising determining whether the WID channel energy level is greater than the predetermined threshold.

15. The method of claim 14, further comprising concluding that the service is not available on the new RF channel if the WID channel energy level is not greater than the predetermined threshold.

16. The method of claim 14, further comprising concluding that the service is available on the new RF channel if the WID channel energy level is greater than the predetermined threshold.

17. The method of claim 16, further comprising permitting channel switching from the current RF channel to the new RF channel.

18. The method of claim 14, further comprising determining whether a decoding error has occurred during decoding of a wide area overhead information symbol (WOIS) if the WID energy level is greater than the predetermined threshold.

19. The method of claim 18, further comprising concluding that the service is not available on the new RF channel if a decoding error has occurred.

20. The method of claim 18, further comprising concluding that the service is available on the new RF channel if a decoding error has not occurred.

21. The method of claim 20, further comprising permitting channel switching from the current RF channel to the new RF channel.

22. The method of claim 11, further comprising determining whether a decoding error has occurred during decoding of a WOIS if no late-detection attempt is initiated.

23. The method of claim 22, further comprising concluding that the service is not available on the new RF channel if a decoding error has occurred.

24. The method of claim 22, further comprising concluding that the service is available on the new RF channel if a decoding error has not occurred.

25. The method of claim 24, further comprising permitting channel switching from the current RF channel to the new RF channel.

26. An apparatus that facilitates detecting broadcast services in a monitored radio frequency (RF) channel in a wireless communication environment, comprising:

a receiver that monitors at least one new RF channel while accessing a service on a current RF channel comprising a broadcast signal;

a memory that stores information related to the RF channels; and

a processor, coupled to the memory, that analyzes a signal received through the at least one new RF channel to determine whether the service is available on the at least one new RF channel based in part on whether the signal comprises duplicate contents as the broadcast signal, and maintains access to the service on the current RF channel when the service is not available on the at least one new RF channel, otherwise switches between the current RF channel and the at least one new RF channel,

wherein the receiver determines whether a decoding error has occurred during decoding of a wide area overhead information symbol to determine whether the signal comprising duplicate contents as the broadcast signal is present in the at least one new RF channel.

27. The apparatus of claim 26, the receiver further comprises a signal monitor that detects the signal in the at least one new RF channel upon at least one of a loss-of-lock event and an application-initiated detection event.

28. The apparatus of claim 26, the receiver further comprises a background monitor that monitors the at least one new RF channel to determine whether the signal comprising duplicate contents as the broadcast signal is present therein.

29. The apparatus of claim 28, wherein the background monitor receives a list of new RF channels via a control channel.

30. The apparatus of claim 28, wherein the background monitor performs RF channel monitoring continuously.

31. The apparatus of claim 28, wherein the background monitor periodically attempts to detect the signal comprising duplicate contents as the broadcast signal in the at least one new RF channel at least once per frame.

32. The apparatus of claim 26, wherein the receiver determines whether a wide area identification channel energy level is above a predetermined threshold level to determine whether the signal comprising duplicate contents as the broadcast signal is present in the at least one new RF channel.

33. A wireless communication apparatus, comprising:

means for accessing a data stream on a current radio frequency (RF) channel comprising a first signal;

means for monitoring a new RF channel comprising a second signal;

means for determining whether the data stream is available on the new RF channel based on whether pilot information is detected in the second signal during a time period when the pilot information is expected to be received in the first signal; and

means for switching between the current RF channel and the new RF channel when the second signal is determined to be present in the new RF channel.

34. The apparatus of claim 33, further comprising means for performing RF channel monitoring upon at least one of a loss-of-lock on the current RF channel and an application-initiated monitoring of the new RF channel.

35. The apparatus of claim 33, further comprising means for performing background monitoring of the new RF channel, wherein the new RF channel is selected from a list of available RF channels received via a control channel.

36. The apparatus of claim 33, further comprising means for evaluating a wide area identification (WID) channel energy level for the new RF channel.

37. The apparatus of claim 36, further comprising means for comparing the WID channel energy level to a threshold level to determine whether the new RF channel contains the second signal.

38. The apparatus of claim 33, further comprising means for determining whether a wide area information overhead symbol (WOIS) decoding error has occurred to assess whether the new RF channel comprises the second signal.

39. The apparatus of claim 33, wherein the first signal on the current RF channel and the second signal on the new RF channel are frame-synchronized.

40. A computer-readable medium having stored thereon computer-executable instructions for:

accessing a service on a first radio frequency (RF) channel comprising a first signal;

monitoring at least one other RF channel;

determining whether a wide area information overhead symbol (WOIS) decoding error has occurred to assess whether the at least one other RF channel comprises a second signal;

determining whether the service is available on the at least one other RF channel based in part on whether the second signal is synchronized with the first signal; and

switching between the first RF channel and the at least one other RF channel when the service is determined to be available in the at least one other RF channel.

41. The computer-readable medium of claim 40, further comprising instructions for performing RF channel monitoring upon at least one of a loss-of-lock on a current RF channel and an application-initiated monitoring of the at least one other RF channel.

42. The computer-readable medium of claim 40, further comprising instructions for performing background monitoring of the at least one other RF channel, wherein the at least one other RF channel is selected from a list of available RF channels received via a control channel.

43. The computer-readable medium of claim 40, further comprising instructions for evaluating a wide area identification (WID) channel energy level for the at least one other RF channel.

44. The computer-readable medium of claim 43, further comprising instructions for comparing the WID channel energy level to a threshold level to determine whether at least one other RF channel contains the second signal.

45. The computer-readable medium of claim 40, wherein the signals on the first RF channel and the at least one other RF channel are frame-synchronized.

46. A processor that executes instructions for increasing throughput in a wireless communication environment, the instructions comprising:

receiving a first radio frequency (RF) channel comprising a first signal;

determining a channel switch time based on a time when a pilot symbol is expected to be received on the first RF channel, an RF settling time for the first RF channel, a direct current acquisition time for the first RF channel, and an automatic gain control acquisition time for the first RF channel;

monitoring a second RF channel at the channel switch time;

determining whether a wide area information overhead symbol (WOIS) decoding error has occurred to assess whether the second RF channel comprises a second signal synchronized with the first signal; and

switching between the first RF channel and the second RF channel when the second signal is determined to be present in the second RF channel.

47. The processor of claim 46, the instructions further comprising performing RF channel monitoring upon at least one of a loss-of-lock on a current RF channel and an application-initiated monitoring of a new RF channel.

48. The processor of claim 46, the instructions further comprising performing background monitoring of the second RF channel, wherein the second RF channel is selected from a list of available RF channels received via a control channel.

49. The processor of claim 46, the instructions further comprising evaluating a wide area identification (WID) channel energy level for the second RF channel.

50. The processor of claim 49, the instructions further comprising comparing the WID channel energy level to a threshold level to determine whether the second RF channel contains the second signal.

51. The processor of claim 46, wherein the first signal on the first RF channel and the second signal on the second RF channel are frame-synchronized.