Dynamic addition of carrier frequency to a wireless coverage area in response to low load

• US 8,270,988 B1
• Filed: 03/27/2008
• Issued: 09/18/2012
• Est. Priority Date: 03/27/2008
• Status: Active Grant

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Sarkar, Debasish, Vargantwar, Sachin R., Oroskar, Siddharth S., Shetty, Manoj
• Primary Examiner(s): Gary, Erika
• Assistant Examiner(s): Fahnert, Marisol
• Application Number:
  US12/056,427
• Time in Patent Office: 1,636 Days
• Field of Search: 370/331, 370/332, 370/328, 370/338, 455/452.1
• US Class Current: 455/452.1
• CPC Class Codes: H04W 16/04 Traffic adaptive resource partitioning
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection

Abstract

A method is disclosed for implementing an overlay carrier frequency in a wireless coverage area in response to low load in the coverage area. Normally, an carrier frequency may be added in response to high load. However, the disclosed method involves adding a carrier frequency in response to low load, as the addition of a carrier may advantageously increase the likelihood of soft handoff in certain situations, and as low load may facilitate operation on the added carrier without the need to add expensive supporting infrastructure that would typically be added to support full operation on an added carrier frequency.

Claims

1. In a radio access network comprising a base station that radiates to define a wireless coverage area, wherein the base station operates on a first carrier frequency in the wireless coverage area, a method comprising:

determining that a level of load in the wireless coverage area is less than a load threshold; and

in response to the level of load being less than the load threshold, activating a second carrier frequency in the wireless coverage area, so that the base station operates on both the first carrier frequency and the second carrier frequency in the wireless coverage area.

2. The method of claim 1, wherein determining that the level of load in the wireless coverage area is less than the load threshold comprises:

analyzing load history over time and identifying a time of day when the level of load in the wireless coverage area tends to be less than the load threshold; and

determining that the level of load in the wireless coverage area is less than the load threshold responsive to a current time being the identified time of day.

3. The method of claim 2, wherein activating the second carrier frequency in response to the level of load being less than the load threshold comprises automatically activating the second carrier frequency in response to occurrence of the identified time of day.

4. The method of claim 1, wherein determining that the level of load in the wireless coverage area is less than the load threshold comprises analyzing a current load of the wireless coverage area and thereby determining that the current load is less than the load threshold.

5. The method of claim 4, wherein activating the second carrier frequency in response to the level of load being less than the load threshold comprises activating the second carrier frequency in response to determining that the current load is less than the load threshold.

6. The method of claim 1, further comprising, after activating the second wireless carrier in the wireless coverage area:

determining that the level of load in the wireless coverage area is no longer less than the load threshold; and

responsive to the level of load in the wireless coverage area no longer being less than the load threshold, de-activating the second carrier frequency in the wireless coverage area, so that the base station operates in the wireless coverage area on the first carrier frequency but not on the second carrier frequency.

7. The method of claim 1, wherein determining that the level of load in the wireless coverage area is less than the load threshold comprises determining that current forward link power usage for the wireless coverage area is less than a power threshold.

8. The method of claim 1, wherein determining that the level of load in the wireless coverage area is less than the load threshold comprises determining that less than a threshold extent of channel element resources is currently in use for the wireless coverage area.

9. In a radio access network comprising a first base station that radiates to define a first wireless coverage area and a second base station that radiates to define a second wireless coverage area, wherein the first base station operates on a first carrier frequency in the first wireless coverage area, wherein the second base station operates on both the first carrier and a second carrier frequency in the second wireless coverage area, and wherein the first wireless coverage area and second wireless coverage area overlap to allow handoff of wireless communication devices between the first wireless coverage area and the second wireless coverage area, a method comprising:

determining that a level of load in the first wireless coverage area is less than a load threshold; and

responsive to the level of load in the first wireless coverage area being less than the load threshold, activating the second carrier frequency in the first wireless coverage area, so that the first base station operates on both the first carrier frequency and the second carrier frequency, to thereby reduce likelihood of inter-frequency handoff between the first wireless coverage area and the second wireless coverage area.

10. The method of claim 9, wherein determining that the level of load in the first wireless coverage area is less than the load threshold comprises analyzing load history over time and identifying a time of day when the level of load in the first wireless coverage area tends to be less than the load threshold.

11. The method of claim 10, wherein activating the second carrier frequency in the first wireless coverage area in response to the level of load being less than the load threshold comprises automatically activating the second carrier frequency in the first wireless coverage area in response to occurrence of the identified time of day.

12. The method of claim 9, wherein determining that the level of load in the first wireless coverage area is less than the load threshold comprises analyzing a current load of the first wireless coverage area and thereby determining that the current load is less than the load threshold.

13. The method of claim 12, wherein activating the second carrier frequency in the first wireless coverage area in response to the level of load being less than the load threshold comprises activating the second carrier frequency in the first wireless coverage area in response to determining that the current load is less than the load threshold.

14. The method of claim 9, further comprising, after activating the second wireless carrier in the first wireless coverage area:

determining that the level of load in the first wireless coverage area is no longer less than the load threshold; and

responsive to the level of load in the first wireless coverage area no longer being less than the load threshold, de-activating the second carrier frequency in the first wireless coverage area, so that the first base station operates in the first wireless coverage area on the first carrier frequency but not on the second carrier frequency.

15. The method of claim 9, wherein, when the first base station operates on the first carrier frequency but not on the second carrier frequency and the second base station operates on the first carrier frequency and the second carrier frequency, the first base station broadcasts a first channel list message (CLM) on the first carrier frequency and the first CLM lists the first carrier frequency but not the second carrier frequency, and wherein activating the second carrier frequency in the first wireless coverage area comprises:

causing the first base station to list in the first CLM both the first carrier frequency and the second carrier frequency and to broadcast the first CLM on both the first carrier frequency and the second carrier frequency.

17. The method of claim 9, wherein determining that the level of load in the first wireless coverage area is less than the load threshold comprises determining that less than a threshold extent of at least one air interface resource for the wireless coverage area is currently in use.

18. The method of claim 17, wherein determining that less than the threshold extent of at least one air interface resource for the wireless coverage area is currently in use comprises determining that current forward link power usage for the wireless coverage area is less than a power threshold.

19. The method of claim 17, wherein determining that less than the threshold extent of at least one air interface resource for the wireless coverage area is currently in use comprises determining that less than a threshold extent of channel element resources is currently in use for the wireless coverage area.

16. In a radio access network comprising a first base station that radiates to define a first wireless coverage area and a second base station that radiates to define a second wireless coverage area, wherein the first base station operates on a first carrier frequency in the first wireless coverage area, wherein the second base station operates on both the first carrier and a second carrier frequency in the second wireless coverage area, and wherein the first wireless coverage area and second wireless coverage area overlap to allow handoff of wireless communication devices between the first wireless coverage area and the second wireless coverage area, a method comprising:

determining that a level of load in the first wireless coverage area is less than a load threshold; and

responsive to the level of load in the first wireless coverage area being less than the load threshold, activating the second carrier frequency in the first wireless coverage area, so that the first base station operates on both the first carrier frequency and the second carrier frequency, to thereby reduce likelihood of inter-frequency handoff between the first wireless coverage area and the second wireless coverage area,

wherein, when the first base station operates on the first carrier frequency but not on the second carrier frequency and the second base station operates on the first carrier frequency and the second carrier frequency, the first base station broadcasts a first channel list message (CLM) on the first carrier frequency and the first CLM lists the first carrier frequency but not the second carrier frequency, and wherein activating the second carrier frequency in the first wireless coverage area comprises causing the first base station to list in the first CLM both the first carrier frequency and the second carrier frequency and to broadcast the first CLM on both the first carrier frequency and the second carrier frequency, and

wherein, when the first base station operates on the first carrier frequency but not on the second carrier frequency and the second base station operates on the first carrier frequency and the second carrier frequency, the second base station broadcasts a second CLM on the first carrier frequency but not the second carrier frequency and the second CLM lists the first carrier frequency but not the second carrier frequency,

the method further comprising, when activating the second carrier frequency in the first wireless coverage area, causing the second base station to list in the second CLM both the first carrier frequency and the second carrier frequency and to broadcast the second CLM on both the first carrier frequency and the second carrier frequency.